Sensor-Driven Variable Gas Flow Burner System

Abstract

A gas destruction system using a gas destroying device communicatively coupled to an electronic controller subsystem for neutralizing unwanted gas emissions. The system includes a gas destruction device and method and can be customized to variable conditions by way of controlling available flow area. The disclosed gas destruction device includes multiple combustion manifolds separated by valves, which allow gas to flow to sets of nozzles as needed to maintain stable combustion. The system consists of multiple nozzles for gas flow, a main shutoff valve, a flow measurement sensor, and an igniter and power source. The combustion products are allowed to flow through the exhaust outlet attached to the combustor. A communicator device is included in the system to send system information, preferably wirelessly. The system can operate autonomously via local or remote controllers, or manually via local or remote commands.

Claims

1. A gas destruction apparatus for the destruction and neutralization of gas from a source, the apparatus comprising: a. a chimney (125); b. at least one vent (107) within said chimney; c. at least one manifold (101) within a burner enclosure (131), said burner enclosure extending from said chimney (125) and said at least one manifold (101) has manifold openings (101A) configured for the distribution of the source gas; d. at least one igniter (106) to ignite said source gas upon distribution from said at least one manifold (101); e. at least one flow control valve (102), said at least one flow control valve (102) connected to the at least one manifold (101) to control flow of source gas into the at least one manifold; f. a length of piping (118) extending from said at least one manifold (101) to said gas source, said piping configured to transport said source gas; g. an electronic controller subsystem (111) having at least one processor running a software program; h. a flame arrestor (116) within said piping (118) proximate said at least one manifold (101); i. at least one shutoff valve (113) within said piping (118) upstream from said flame arrestor (116) and said flow control valves (102); j. a gas concentration sensor subsystem (105) attached to the piping (118), said gas concentration sensor subsystem (105) configured to receive a sample of source gas from said piping (118) and to communicate with the electronic controller subsystem (111); k. a power source (109) powering the apparatus; and l. at least one sensor, each of said at least one sensor configured to monitor at least one process variable of the gas source; wherein said at least one process variable comprises gas pressure, gas flow, gas concentration, gas temperature, exhaust temperature, thermal flux, and humidity; wherein said at least one sensor generates values; wherein said sensor-generated values are sent to the electronic controller subsystem (111) for analysis by the software program; wherein the electronic controller subsystem generates output triggering at least one action to actuate at least one system element.

2. The apparatus of claim 1 wherein said at least one system element is one of: the at least one shutoff valve, the at least one flow control valve, and the igniter.

3. The apparatus of claim 1 wherein said at least one manifold (101) further comprises flow control valves (102) between manifold openings (101A) and said pipe (118), said control valves (102) being in communication with said controller subsystem (111) to control gas distribution through said openings (101A) and being powered by said power source (109).

4. The apparatus of claim 1 further comprising at least one converging-diverging housing (112) adjacent to the at least one of the manifold to entrain combustion air.

5. The apparatus of claim 1 further comprising at least one flame holder device (114) adjacent to the at least one of said manifold to improve combustion stability.

6. The apparatus of claim 1 wherein said gas concentration sensor subsystem (105) comprises: a. a bypass having inlet (259A, 309A) configured to receive the sample of said source gas from the piping 118; b. a process valve (266, 308) configured to control flow of said source gas through said bypass; c. a conditioner element (253, 303) configured to receive the sample of said source gas from the piping 118 through the bypass; d. a gas concentration sensor (252, 302) configured to measure said sample passed through the conditioner element, said gas concentration sensor (252, 302) continuously monitoring said sample and communicating measurements to said electronic controller subsystem; e. an outlet (259B, 309B) for egress of the sample from the gas concentration sensor subsystem.

7. The apparatus of claim 1 further comprising a recalibration system (250) for monitoring drift in one of said at least one sensor, said recalibration system (250) comprising: a. a bypass having inlet configured to receive a sample of said source gas from the piping 118 and pass the source gas sample to said one of said at least one sensor for monitoring; b. a process valve configured to control flow of said source gas through said bypass; c. an outlet for egress of the sample from the recalibration system; d. at least one compressed gas cylinder (268A, 268B); e. pressure regulators (265A, 265B,) affixed to each of said at least compressed gas cylinders (268A, 268B); f. at least one calibration control valve (251A, 251B), said at least one calibration control valve (251A, 251B) closed during normal monitoring operation; wherein when recalibration is triggered, process gas valve 266 is closed and each of said at least one calibration control valve 251A and 251B are opened sequentially, wherein upon opening of each of said at least one calibration control valves, calibration gas within one of said at least one compressed gas cylinders (268A and 268B) corresponding to the opened calibration control valve flows to said one of the at least one sensor; wherein said calibration gas is measured and continues to flow through said one of the at least one sensor until a measured value is within a pre-determined range, with measured calibration gas passing to the egress outlet; and wherein upon detecting the measured value in the pre-determined range, said at least one calibration valve is closed, process gas valve is opened, and recalibration system (250) is returned to normal monitoring operation.

8. The apparatus of claim 7 wherein said recalibration system is integrated with the gas concentration subsystem (105) to monitor and recalibrate the gas concentration sensor.

9. The apparatus of claim 1 wherein one of said at least one sensors comprises at least one exhaust temperature sensor (115) within said chimney (125), said exhaust temperature sensor (115) monitoring temperature within said chimney (125) and reporting said temperature to said controller subsystem (111).

10. The apparatus of claim 1 further comprising at least one thermal flux sensor (115) within said chimney (125), said thermal flux sensor (115) quantifying gas destruction within said chimney (125) and reporting said temperature to said controller subsystem (111).

11. The apparatus of claim 1 further comprising at least one thermal mass device (117) within said chimney (125), said thermal mass device (117) being placed to reignite said source gas after an interruption.

12. The apparatus of claim 1 further comprising multiple burner enclosures, each of said burner enclosures having at least one manifold connected to said piping.

13. A method for destructing gases to neutralize emissions, the method comprising: a. causing gas to flow from a gas source to a monitoring and destruction path of a gas destruction system having a controller subsystem, said controller subsystem having at least one processor running a state machine program in communication with at least one circuit to operate the destruction system; b. loading system parameters to the controller subsystem; c. generating by each of a plurality of sensors along the monitoring and destruction path a value transmitted to the controller subsystem, one or more of the plurality of sensor-generated values indicative of measurements of continuously monitored process variables within the system; d. controlling by the at least one circuit at least one gas destruction element and at least one actuator of the system based on the loaded parameters and sensor-generated values, wherein said control subsystem analyzes the loaded parameters and sensor-generated values, implements control logic, and generates output triggering at least one system operating action to promote stable functionality of the system; e. controlling by the at least one circuit a safety operating loop wherein one or more of the sensor-generated values falling outside a pre-determined process variable threshold triggers a system safety action; and f. storing sensor-generated values and system actions in a storage database; wherein, loaded parameters and process variable measurements customize the destruction of gases under variable conditions.

14. The method of claim 12 wherein said state machine program comprises at least a first state, a second state, and a third state, with each state including entry actions, an operating loop, and exit actions, said program configured to: a. upon entering said first state, execute entry actions comprising loading parameters, monitoring system sensors, configuring instruments, sending operator notifications, actuating closure of all valves, and confirming blowers are powered off; b. upon detection of a transition trigger, execute exit actions then transitioning to the second state, said transition trigger comprising pre-set conditions and external commands; c. upon entering said second state, execute entry actions comprising opening main shutoff valve, powering igniters, and starting an ignition timer, and commanding operation of system elements and entering a second state operating loop comprising checking temperatures, temperature rates, and timeout status of the ignition timer and implementing control algorithms to promote stable ignition; d. upon detection of a transition trigger comprising a timeout or ignition, execute exit actions comprising sending operator notifications then transitioning to the third state if temperature measurements meet threshold levels or back to the first state if a timeout is reached without ignition; e. upon entering said third state, execute entry actions comprising sending operator notifications and commanding blower run speeds and entering a third state operating loop comprising checking temperatures to confirm burning, monitoring process variables, and implementing control algorithms to maintain stable burning and promote complete gas destruction; and f. upon detection of a transition trigger comprising detection of out of bounds process variables, execute exit actions comprising sending operator notifications, closing valves, and shutting down operation of system elements, then transitioning back to the first state or initiating system shutdown. The method of claim 1 wherein said parameters comprise variable thresholds, safe bound for sensor readings, telemetry reporting frequency, presence/absence of a blower motor, desired operating speed of the blower motor during the ignition state, and desired operating speed of the blower during the burn state, wherein said parameters are determined by system site requirements, reporting requirements, and system instrumentation.

15. The method of claim 1 wherein said process variables comprise at least one of: pressure, flow, gas concentration, gas temperature, flame temperature, and thermal flux.

16. The method of claim 1 wherein said at least one operating action comprises actuating at least one system element to change process variable values.

17. The method of claim 1 wherein said safety action comprises at least one of: commanding the state machine program to an idle state, extinguishing at least one gas destructing element, or powering off the gas destructing system.

18. The method of claim 1, further comprising exchanging information with an external electronic device communicatively coupled to the system, said information comprising sensor-generated values, updated parameters, and operator instructions.

19. A gas destruction system using a gas destructing device communicatively coupled to an electronic controller subsystem for neutralizing gas emissions, the system comprising: a. the gas destructing device comprising: i. a chimney (125); ii. at least one vent (107) within said chimney; iii. at least one manifold (101) within a burner enclosure (131), said burner enclosure extending from said chimney (125) and said at least one manifold (101) has manifold openings (101A) configured for the distribution of the source gas; iv. at least one igniter (106) to ignite said source gas upon distribution from said at least one manifold (101); v. at least one flow control valve (102), said at least one flow control valve (102) connected to the at least one manifold (101) to control flow of source gas into the at least one manifold; vi. a length of piping (118) extending from said at least one manifold (101) to said gas source, said piping configured to transport said source gas; vii. a controller subsystem (111) having at least one microcontroller with at least one microprocessor running a software program; viii. a flame arrestor (116) within said piping (118) proximate said at least one manifold (101); ix. at least one shutoff valve (113) within said piping (118) upstream from said flame arrestor (116) and said flow control valves (102); x. a gas concentration sensor subsystem (105) attached to the piping (118), said gas concentration sensor subsystem (105) configured to receive a sample of source gas from said piping (118) and to communicate with the electronic controller subsystem (111); xi. a power source (109) powering the apparatus; and xii. at least one sensor, said at least one sensor configured to monitor process variables of the gas source; wherein said at least one process variable comprises gas pressure, gas flow, gas concentration, gas temperature, exhaust temperature, thermal flux, and humidity; wherein said at least one sensor generates values; wherein said sensor-generated values are sent to the electronic controller subsystem (111) for analysis by the software program; wherein the electronic controller subsystem generates output triggering at least one action to actuate at least one of the main shutoff valve, the flow control valve, the at least one igniter, and the power source; and b. electronic controller subsystem comprising at least one processor running a state machine program, the program configured to: i. receive system parameter input; ii. receive sensor-generated values from said sensors, the sensor-generated values indicative of measurements of continuously monitored process variables within the system; iii. analyze the system parameter input and sensor-generated values; iv. implement control algorithm to determine next steps to promote stable functionality of the system; v. generate output triggering at least one system operating action; vi. transmit operating action via circuits to actuate operating elements of the system to affect process variables; vii. monitor sensor-generated values and rerunning control algorithm until stable functionality of the system is achieved; viii. maintain stable process variables; and ix. store sensor-generated values and system actions in a storage database. wherein, loaded parameters and process variable measurements customize the destruction of gases under variable conditions.

20. The apparatus of claim 19 further comprising a recalibration system for monitoring drift in one of said at least one sensor, said recalibration system comprising: a. a bypass having inlet configured to receive a sample of said source gas from the piping 118 and pass the source gas sample to said one of said at least one sensor for monitoring; b. a process valve configured to control flow of said source gas through said bypass; c. an outlet for egress of the sample from the recalibration system; d. at least one compressed gas cylinder (268A, 268B); e. pressure regulators (265A, 265B,) affixed to each of said at least compressed gas cylinders (268A, 268B); f. at least one calibration control valve (251A, 251B), said at least one calibration control valve (251A, 251B) closed during normal monitoring operation; wherein when recalibration is triggered, process gas valve 266 is closed and each of said at least one calibration control valve 251A and 251B are opened sequentially, wherein upon opening of each of said at least one calibration control valves, calibration gas within one of said at least one compressed gas cylinders (268A and 268B) corresponding to the opened calibration control valve flows to said one of the at least one sensor; wherein said calibration gas is measured and continues to flow through said one of the at least one sensor until a measured value is within a pre-determined range, with measured calibration gas passing to the egress outlet; and wherein upon detecting the measured value in the pre-determined range, said at least one calibration valve is closed, process gas valve is opened, and recalibration system (250) is returned to normal monitoring operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is an overview drawing of an example gas burner system (100), showing manifolds (101), valves (102, 113), burner nozzle enclosure (131), chimney (125), sensors (104, 105, 110, 115, 119, 128), and electronic controller subsystem (111), in accordance with the disclosed invention;

[0006] FIG. 2 is a detailed view of an example of a combustion manifold (101), including nozzles (103), converging-diverging housings (112), igniter (106), and manifold valve (102), in accordance with the disclosed invention;

[0007] FIG. 3 is an alternate valve arrangement, where no master shutoff valve is present, but instead each branch or pair of branches is controlled by an individual valve (102)), in accordance with the disclosed invention;

[0008] FIG. 4 is an alternate device configuration illustrating valve-controlled branches which regulate gas flow to additional gas destruction devices (139), each with their own control valve (102) and ignition source (106), in accordance with the disclosed invention;

[0009] FIG. 5 is a detailed top-down view showing the inside of the burner nozzle enclosure (131), and the spatial arrangement of manifolds (101), nozzles (103), and igniters (106), in accordance with the disclosed invention;

[0010] FIG. 6 is a diagram of the gas concentration sensor subsystem (105), consisting of gas concentration sensors (122), gas conditioner (123), enclosure (124), and auto-recalibration system, including cylinders of reference gas (120) and valves (121), in accordance with the disclosed invention;

[0011] FIG. 7 is an alternate valve (121) arrangement for recalibration equipment, using fewer valves than FIG. 6 through the use of two 3-way valves to switch the state of the device, in accordance with the disclosed invention;

[0012] FIG. 8 is an alternate flame arrestor device (116) using water or other non-flammable liquid, in accordance with the disclosed invention;

[0013] FIG. 9 is an alternate embodiment for a burner system which drafts low-pressure methane using a fan or blower (302), in accordance with the disclosed invention;

[0014] FIG. 10 is a top-level state diagram of control logic for operation of the gas burner system (100) in accordance with the disclosed invention;

[0015] FIG. 11 is a state diagram detail of safety checks (404), in accordance with the disclosed invention;

[0016] FIG. 12 is a state diagram detail of the burn state control law (409), in accordance with the disclosed invention;

[0017] FIG. 13 is an overview state diagram of control logic for operation of the gas burner system in alternate configuration employing blower flow control, in accordance with the disclosed invention; and

[0018] FIG. 14 is a state diagram of control logic for operation of the gas concentration sensor subsystem (105), including logic for auto-calibration, in accordance with the disclosed invention.

[0019] FIG. 15 is a state diagram of control logic for source modeling in accordance with the disclosed invention; and

[0020] FIG. 16 is a flow chart overviewing the electronic controller subsystem of the present invention.

ELEMENT INDEX

[0021] FIG. 1, 5: [0022] 100 Gas burner system [0023] 101 Manifolds [0024] 101A manifold inlet [0025] 102 Valves [0026] 103 Nozzle [0027] 104 Flow sensor [0028] 105 Gas concentration sensor subsystem [0029] 106 Igniters [0030] 107 Exhaust vent [0031] 108 Communicator [0032] 109 Power source [0033] 110 Pressure sensor [0034] 111 Electronic controller subsystem (microcontroller and software) [0035] 112 Converging-diverging housing [0036] 112A Flame holder [0037] 113 Main shutoff valve [0038] 114 Flame holder device [0039] 115 Exhaust/flame temperature sensor [0040] 116 Flame arrester [0041] 117 Thermal mass device [0042] 118 Piping [0043] 119 Feed gas temperature sensor [0044] 121 Calibration control valves [0045] 125 Chimney [0046] 127 Weather-shielding shroud [0047] 128 Thermal flux sensor [0048] 129A Bypass intake [0049] 129B Bypass outtake [0050] 130 Heater [0051] 131 Burner enclosure [0052] 132 Refractory material [0053] 133 Air inlet [0054] 138 Blower [0055] 139 Additional gas burner modules part of a gas burning system [0056] 140 Guy lines [0057] FIG. 3: [0058] 152 Valve [0059] 154 Converging-diverging housing [0060] 156 Igniter [0061] 157 Thermal mass device [0062] 159 Piping [0063] 162 Flame arrestor [0064] FIG. 16: [0065] 170 Processor of controller subsystem (microcontroller/microprocessor) [0066] 172 Circuits of controller subsystem [0067] 174 Computer program run by processor [0068] 176 Sensor-generated data/values [0069] 178 Actuators [0070] 180 External electronic device [0071] 182 Local storage database [0072] 182 Remote storage database [0073] 190 Burner system elements responsive to controller subsystem [0074] FIG. 4: [0075] 200A&B Chimney [0076] 201A&B Manifolds [0077] 202A&B Valve [0078] 206A&B Igniter [0079] 216A&B Flame arrestor [0080] 218 [0081] 219 Piping [0082] FIG. 6: [0083] 250 Recalibration System [0084] 251A Valve [0085] 251B Valve [0086] 252 Gas concentration sensor [0087] 253 Gas conditioner (desiccant chamber) [0088] 254 Waterproof enclosure [0089] 259A-D piping [0090] 260 Heater [0091] 264 Auto-calibration controller subsystem [0092] 265A Pressure regulator [0093] 265B Pressure regulator [0094] 266 Process gas valve [0095] 267 Communicator [0096] 268A Pressurized calibration gases [0097] 268B Pressurized calibration gases [0098] FIG. 7: [0099] 300 Recalibration System [0100] 302 Gas concentration sensors [0101] 303 Gas conditioner (desiccant chamber) [0102] 304 Waterproof enclosure [0103] 305 Auto-calibration electronic controller subsystem [0104] 306 Heater [0105] 307 Communicator [0106] 308 Source gas/calibration gas toggle valve [0107] 309A-F pipe [0108] 310 Calibration gas selection toggle valve [0109] 315A Pressure regulator [0110] 315B Pressure regulator [0111] 318A High pressure cylinder [0112] 318B High pressure cylinder [0113] FIG. 8: [0114] 350 Liquid-based flame arrestor [0115] 351 Liquid [0116] 352 Chamber [0117] 353 Entrance pipe [0118] 354 Exit pipe [0119] FIG. 9: [0120] 370 Atmospheric pressure burner [0121] 371 Burner [0122] 372 Blower [0123] 373 Chimney [0124] 374 Flame arrestor [0125] 375 Pressure sensor [0126] 376 Temperature sensor [0127] 377 Gas burner control system [0128] 378 Igniter [0129] 379 Communicator [0130] FIG. 10: [0131] 400 Preferred control logic of the gas burner system electronic controller [0132] 401 Electronic controller idle state [0133] 402 Electronic controller ignition state [0134] 403 Electronic controller burn state [0135] 404 Electronic controller safety check state [0136] 405 Electronic controller exhaust temperature check [0137] 406 Electronic controller exhaust temperature rate check [0138] 407 Electronic controller ignition state timeout [0139] 408 Electronic controller process variable measurement state [0140] 409 Electronic controller burn control law update state [0141] 410 Electronic controller load parameters [0142] 412 Electronic controller configure instruments [0143] 414a Electronic controller idle state entry events [0144] 414b Electronic controller ignition state entry events [0145] 414c Electronic controller burn state entry events [0146] 415a Electronic controller idle state operating loop [0147] 415b Electronic controller ignition state operating loop [0148] 415c Electronic controller burn state operating loop [0149] 418a Electronic controller idle state exit events [0150] 418b Electronic controller ignition state exit events [0151] 418c Electronic controller burn state exit events [0152] 420 Electronic controller ignition timer start [0153] FIG. 11: [0154] 431 Safety parameteroxygen in gas source [0155] 432 Safety parametergas concentration [0156] 433 Safety parameterpressure limits [0157] 434 Safety parameteracceptable temperature [0158] FIG. 13: [0159] 450 Set point [0160] 451 Error/difference [0161] 452 Control law adjustments based on error [0162] 453 Blower [0163] 454 Cover/pond pressure [0164] 455 Sensor block/sensor readings [0165] 456 State estimator [0166] 457 Feedback signal [0167] FIG. 12. [0168] 490 Current state process variables [0169] 491 Pressure greater than threshold state [0170] 492 Increment state change [0171] 493 Pressure below threshold state [0172] 494 Decrement state change [0173] 495 State table [0174] FIG. 14: [0175] 500 Preferred control logic of the auto-calibration electronic controller [0176] 501 Electronic controller normal operation state [0177] 502 Electronic controller monitor for sensor drift state [0178] 503 Electronic controller calibration state [0179] 504 Electronic controller valves gas #1 state [0180] 505 Electronic controller sensor stabilization state [0181] 506 Electronic controller valves gas #2 state [0182] 507 Electronic controller sensor stabilization state [0183] 508 Electronic controller valves normal state [0184] FIG. 15: [0185] 550 Runtime data [0186] 551 Learning phase [0187] 552 Future behavior prediction [0188] 553 Subsystem control decisions

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT AND ALTERNATIVES

Definitions

[0189] As used herein, the term gas burner system shall refer to a software-controlled assembly of elements used to oxidize flammable gases.

[0190] As used herein the term gas destruction shall refer to the breaking down of gas through any method such as burning, thermalizing, or the use of an electric generator.

[0191] As used herein the terms flare, and combustor all refer to the destruction of gas through burning and will be used herein interchangeably.

[0192] As used herein, the term nozzle shall refer to an opening used to direct the flow of gas, of any cross-section or profile, including a simple orifice.

[0193] As used herein, the term sensor shall refer to a device which detects or measures a gas, liquid or other physical property and records, indicates, or otherwise responds and may, also herein referred to as a meter. A sensor or meter in some cases may be a single sensing element but may also refer to an entire electromechanical package with higher-level analytical capabilities such as pressureor temperaturecompensation or totalizing and may include multiple sensing elements.

[0194] As used herein, the term manifold shall refer to a section of gas-conveying tubing or piping with one or more openings used to distribute gas to one or multiple points.

[0195] As used herein, the term flame arrester shall refer to a device designed to halt the propagation of flame.

[0196] As used herein, the term flame holder shall refer to a device intended to create a low-speed eddy to prevent the flame from being blown out, and which typically defines the location of the base of the flame.

[0197] As used herein, the term thermal mass device shall refer to a piece of material used to hold heat, usually for the purpose of maintaining stable, uninterrupted combustion.

[0198] As used herein, the term converging/diverging housing shall refer to a device through which flow is constricted and subsequently allowed to expand, for example having an hourglass profile

[0199] As used herein, the term refractory material shall refer to a material that is resistant to decomposition by heat or chemical attack, retaining its integrity at high temperatures, and is typically for insulative purposes.

[0200] As used herein, the term communicator shall refer to a device that allows the transmission of data.

[0201] As used herein, the term flameout shall refer to extinguishment of a flame, usually due to interruption of gas supply, high levels of dilution of fuel gas with non-combustible components, or excessive wind or disturbance.

[0202] As used herein, the term backburning shall refer to flame present anywhere other than the intended design location. Typically, this is a consequence of low flow.

[0203] As used herein, the term stable combustion shall refer to combustion that is uninterrupted by periods of low flow, flameout, or back burning.

[0204] As used herein, the term complete combustion shall refer to combustion that occurs with an excess of oxygen, such that at least 95% (but often higher) of fuel hydrocarbons are broken down completely to water and carbon dioxide.

[0205] As used herein, the term process gas shall refer to a gas of either pure or mixed composition to be directed through a gas burner system.

[0206] Many applications require flammable gases to be destroyed-in order to remove unwanted industrial by-products, for safety, to generate verifiable carbon offsets, or other environmental reasons. These flammable gases come from many sources including but not limited to manure ponds, active and shut coal and trona mines, palm oil waste ponds, bagasse waste ponds, oil and gas facilities, industrial chemical processing plants, mud volcanos, natural methane vents and landfills.

[0207] Often a system will be required to compensate for varying conditions such as flow or composition in the source gas to maintain stable operation. Currently systems rely heavily on manual intervention for monitoring, control, and recalibration, thereby limiting current systems to gas sources large enough to justify the labor or resulting in intermittent or inefficient operation when sufficient attention is not available.

[0208] To be applicable to the widest use cases, gas destruction requires a stable chemical destruction process, efficient and/or complete destruction of the target gas, upstream source management, safety controls, accurate quantitative verification of the destruction, and minimum operational cost in both capital expenditure and labor. The disclosed system neutralizes gas emissions, such as methane, on site using a minimal hardware design with efficient software controls to create a system that requires significantly less intervention and thus expands the scope of applicability for reliable gas capture and destruction with minimal land impact.

[0209] The disclosed gas destruction system relies on modularity to provide variable and controllable effective flow area. There are two embodiments of this concept disclosed: The first modularity is where the modules are burner manifolds within a single enclosure as illustrated in FIGS. 1 and 9.

[0210] The second is where the modules are separate enclosures each containing one or more manifolds, which may themselves be separately controllable as illustrated in FIG. 4.

[0211] Both of these modularities, as well as combinations thereof and others which will be known to those skilled in the art demonstrate the concept of modular controllable flow area in different forms.

[0212] The different elements which make up the alternative embodiments may be used in combination with each other as well as with elements of the preferred embodiment to create a gas destruction system.

[0213] All sensors report raw and/or analyzed data to the user programmable electronic controller subsystem where the data is either forwarded to a remote location or is stored for subsequent onsite viewing. For optimal performance of the system, the presets within the sensors can be updated by the electronics controller subsystem to reflect user updates with all changes being handled remotely.

[0214] The disclosed gas destruction system is set up at a gas emission site such as a coal mine or manure pond. The example system, illustrated in FIG. 1 as a gas burner system (100), includes a chimney section, a combustion section, and a transfer/monitoring section. The distal portion of the piping 118 (not illustrated) is designed to capture the source gas. Examples of source gas capture construction are disclosed in more detail hereinafter.

[0215] Although not all wires are illustrated for drawing clarity, the sensors (104, 105, 110, 115, 119), igniters (106), controller (111) and communicator (108) are all powered by one or more power sources (109), which are preferably batteries. The batteries are preferably rechargeable through the use of a thermoelectric charger that creates a current from the thermal energy generated by the combustor. The battery may alternatively be charged by using solar panels, wind, or the motion of the waves. Alternatively, the battery contains sufficient charge to power the system for long durations to last between regular maintenance cycles. The power system is preferably lightweight to allow for ease of transportation. The wiring from the battery to the flow measuring sensor, igniter, and communicator should be weatherproof to be able to withstand a wide range of temperatures, corrosive environments, and water. In an alternative embodiment of the invention, power is provided by mains power, or a generator. The method of powering the device will be dependent upon the location of the system and will be known to those skilled in the art.

[0216] The system may alternatively be powered by supercapacitors, which are advantageous for rechargeability in very cold environments. Alternatively, active heating of the electronics and piping may be used in these environments, either through use of combustion heat or electric power. Alternatively, electronics and piping may be kept warm or above freezing by way of submerging them in a body of water known to not freeze or burying them in soil to a depth sufficient to protect from freezing.

[0217] For ease of reference, the apparatus of the present invention is described with reference to three sections corresponding to purpose within the gas destructing system. Namely, section A is an exhaust/chimney section, section B is a gas destructing section, and section C is a transfer/monitoring section. From the point of the gas source, section C transitions into section B which transitions to section A, thus forming a whole gas destructing system. The transfer/monitoring section captures the gas and prepares the system for burning in the gas destructing/combustion section, after which the burned gas exhaust is released though the chimney section. Sections B and C combined form a monitoring and destructing path for gas to flow from the capture site and ultimately yield neutral emissions.

Section A: Chimney/Exhaust

[0218] In the preferred embodiment, a chimney (125) is used to enhance natural convection, drafting air for combustion and cooling the exhaust gases before they are exhausted into the atmosphere. The dimensions and aspect ratio for an effective chimney is determined by flame temperature and must entrain enough air to create complete combustion fully inside the enclosure and to cool the exhaust stream below the temperature limits of the instruments. The typical temperature limit of the instruments is 1000 C. It is also preferable to maintain flame temperatures below approximately 1500 C. to minimize the production of NOx, a harmful air pollutant. In the illustrated embodiment, the chimney (125) and the burner enclosure (131) are the same diameter and integrated directly together. This example diameter is preferably 14-28 for ease of transportation, although the outer diameter may be larger in order to accommodate higher gas flow design conditions. The chimney is preferably an aspect ratio between 4:1 and 7:1 (height:diameter). Alternatively, the chimney (125) may be a smaller diameter than the burner enclosure (131).

[0219] The dimensioning of the chimney depends on flow and gas type and concentration. To achieve the proper temperatures, the chimney dimensions must be matched to the heat power of the gas being burned and the dilution ratio of the entrained air. For example, higher gas flows, higher gas concentration, and higher gas heat value all contribute to the higher temperatures and thus the need for a taller chimney. A wider chimney might be needed to expand the gas capacity of the burner. Chimney thermal design will be known to a person versed in the art.

[0220] Generally, the shape of the enclosure is a cylindrical prism, but other shapes may alternatively be used such as a box, polygonal prism, or a cone. The material of the enclosure and chimney walls can be thin sheet metal that is able to be joined together at the installation site to allow for ease of transportation but may alternatively be made of ceramic or preformed metal piping or ducting, or other tubular metal structures. The chimney (125) is preferably broken into several assemblable modules for ease of transportation, although it may alternatively be formed from a monolithic structure. The chimney is preferably lined with flexible fibrous refractory material (132) in order to protect the longevity of the structure through its insulative properties, but this is not always required. The dimensions, aspect ratio, materials, and assembly of the chimney may be modified according to thermal design needs and site-by-site source gas composition, which will be known to those skilled in the art.

[0221] An exhaust vent (107) is attached to the top of the chimney (125). The shape of the exhaust vent (107) is preferably a static baffle which prevents wind and weather intrusion into the chimney (125). The exhaust vent (107) may alternatively be a tube with a wind vane feature similar to wind directional chimney caps, which will pivot the exhaust outlet to face away from the wind as the wind blows on the vane. The exhaust vent (107) is preferably covered by a wire mesh to further prevent debris and snow from entering the chimney (125), or alternatively with a one-way valve. In the illustrated embodiment, wire mesh or gratings are also used to cover the air inlet, or louver, (133) at the bottom of the burner enclosure (131) to prevent snow, debris, and animals from entering. Alternatively, the chimney (125) is bent to make the exhaust outlet horizontal, instead of vertical, to prevent debris from entering the burner enclosure (125). The chimney (125) is preferably made of sheet metal but may alternatively be made of plastic or a solid metal shape. In an alternate embodiment, no specially shaped exhaust outlet is used, allowing exhaust gases to exit directly from the chimney, which may be covered by wire mesh or left open.

[0222] The embodiments illustrated herein use a weather shielding shroud (127) to prevent blockage of the air inlets by snow accumulation, preferably formed from perforated sheet metal bent into cylindrical or conical shape. This shielding shroud (127) also minimizes flame pressure disturbances due to wind. Alternatively, the shielding shroud (127) may be made from metal mesh, or may be made from plastic mesh, and may be a rectangular, triangular, or a polygonal prism. Alternatively, the shield may be absent.

[0223] As previously mentioned, the chimney (125) integrates directly with the burner enclosure (131) thus transitioning the gas destructing/combustion section B of the system to the exhaust section A. Destructed gas exhaust rises through the chimney (125) exiting as neutral emissions through vent (107). At least one temperature sensor (115) located along a wall of the chimney as shown in FIG. 1, monitors temperature from the rising exhaust and reports temperature information to the electronic control subsystem to confirm gas destruction.

Section B: Gas Destruction/Combustion

[0224] As illustrated in FIG. 1, the burner nozzles (103) are provided with air flow through an open-air inlet area (133) at the bottom of the burner enclosure (131), which creates a draft through the chimney (125). The air intake cross-sectional area (133) is preferably able to be tuned by use of a louver or other restriction, which may be mechanized, but may alternatively be manually operable or static. Optimally the air intake (133) would be tied to the electronic controller subsystem (111), thereby making the control automatic based on the desired flow rate and temperature as determined by the electronic controller subsystem (111). The air intake may alternatively be a simple set of openings with no louver. The dimensions, aspect ratio, materials, and assembly of the combustion enclosure may be modified according to thermal design needs and site-by-site source gas composition, which will be known to those skilled in the art.

[0225] The combustion section B, an example of which is illustrated in more detail in FIG. 2, consists of a combustion manifold (101) separated by a valve (102), which allows gas to flow to sets of nozzles (103), mixing with air, within the burner enclosure 131 as needed to maintain stable combustion over a large range of flows. Although FIG. 2 shows the detail of a single combustion manifold 101, as illustrated in the example system of FIG. 1 as well as additional examples disclosed herein, multiple combustion manifolds 101 are generally used. The number and configuration of manifolds and corresponding elements is dependent upon the end use, e.g. source, production, environment, power source, etc., and will be known to those skilled in the art.

[0226] As illustrated each manifold (101) contains one or more nozzles (103) which serve to direct the flame. The inside diameter of the nozzles (103) will be chosen based on the specific gas composition of the source, but are typically identical within a gas burner system and are between 0.02 and 0.5 with the preferred dimensioning known to those skilled in the art.

[0227] In the illustrated embodiment, these nozzles (103) are screw fittings that are interchangeable, to allow for tuning to the specific gas properties of the site, such as gas density. The use of threaded nozzles (103) saves time and money by eliminating the replacement of the manifold (101) when the equipment is moved to a site containing a different gas composition. Alternatively, a simple tube, hole, or non-interchangeable nozzle may be used, in which case the nozzles may be permanently affixed or directly integrated into the manifold. The number of nozzles (103) used will be determined by the spatial arrangement of the manifolds (101) inside the burner enclosure (131), with the goal of evenly distributing gas in order to efficiently mix with combustion air. Piping diameters may also be adjusted to the specific properties of the gas and will be known to those skilled in the art.

[0228] Alternatively, the multiple nozzles (103) can be simple orifices or include converging-diverging housing (112) as described herein after. The converging-diverging housings (112) can be molded at the time of manufacture or be welded, bolted, clamped, threaded, or riveted onto the nozzles (103) or manifolds (101). It is preferable that they be conjoined by a metal structure (112A) and mounted in a removable fashion, providing the option of use with or without the housings (112). The metal structure (112A) further raises the converging-diverging house (112) above the nozzles (103), permitted additional air flow when required by the application.

[0229] At least one igniter (106) is incorporated within the combustion section B to ignite the air and gas mixture. Although only one igniter (106) is required, in systems that are exposed to harsh environments and/or long terms between maintenance, a backup igniter can be added. In these cases, the software would recognize the lack of ignition in the primary igniter and switch power to the secondary, or backup, igniter, or would energize both simultaneously.

[0230] The igniters must be sufficiently close to the burners' converging-diverging housing (112), or nozzles (103), to ignite the gas, usually within 3 inches of the exit of the converging-diverging housing (112) (if present) and preferably within 0.5 inch of the exit of the converging-diverging housing (112). Each valved modular unit must have at least one igniter. The example depicted in FIG. 2 is a detailed view of a modular unit, consisting of a gas manifold (101) controlled by a valve (102), gas orifices (103), a converging-diverging nozzle (112), a flame holder device (114), and an igniter (106). As shown in FIG. 2, chimney (200A), if a single burner module contains multiple valve-controlled manifolds within the same enclosure, a single igniter may be used for both sets of manifolds. In this case, manifolds must be located close enough to one another for ignition to transfer from one module to the next. The geometric parameters which create this condition are dependent on the fuel gas mix and flow conditions, and will be known to those skilled in the art. Modular units can contain greater or fewer components, for example, two or more igniters per valved modular unit are preferred for increased reliability and longer maintenance intervals. Each burner will contain one or more modular units.

[0231] The combustion products rise up through the chimney (125) to exit into the atmosphere through the exhaust outlet (107). Also illustrated in FIG. 2 is an optional thermal mass device (117) that is described in more detail hereinafter.

Section C: Transfer/Monitoring

[0232] Along the monitoring and combustion path, the transfer/monitoring section C contains the monitoring and transferring equipment required to move the gas from the source to the combustion section B. The igniter (106), valves (102, 113), sensors (104, 105, 110, 115, 119), electronic controller (111), and the communicator (108) are all powered by the power source (109) and controlled by the electronic controller subsystem (111). The individual elements are described in more detail hereinafter. In some applications a blower (138) is required to boost the flow of the source gas and as illustrated the blower (138) is placed prior to the start of the transfer/monitoring section C.

[0233] Tubing, or piping, (118) is used to move the source gas from the initiating location to the burner enclosure (131). In the illustrated embodiment of FIG. 1, the piping (118) is preferably rigid to allow for simple mounting of sensors and made of 2.0-inch stainless steel or PVC plumbing pipe, which are preferred for their corrosion-resistance. Depending on the application, source gas properties, and environment, the piping diameter may be altered along with the applicable materials and flexibility. The materials and size required for optimal operation and pipe connection will be known to those skilled in the art.

[0234] Once the source gas enters the piping (118) a temperature sensor (119) takes a reading. As there is no maximum or minimum threshold temperature for operation, this is generally part of data reporting, and not part of the control logic, although in some applications the temperature can be relevant, and maximums and minimums would be added to the pre-programmed criteria. In most applications, however, gas temperature is simply logged, sometimes for the purpose of temperature-compensation in flow measurements (adjusting to standard temperature for reporting purposes).

[0235] As source gas proceeds along the piping (118) toward the burner enclosure (131), a small sample enters into a tubing bypass intake (129A) where it is analyzed in the gas concentration sensor subsystem (105) as described hereinafter. The gas is generally expelled from the source piping into the gas concentration sensor subsystem (105) by the source pressure; however, if the source pressure is insufficient, it is drawn in by means of a pump, such as a peristaltic pump. Typically, the flow rate through the gas concentration sensor subsystem (105) is in the range of 0.1-0.5 L/min, which is much less flow than that which passes through the transfer piping (118). A small sample is all that is required for the composition analysis, and gas is returned to the main gas flow through tubing bypass outtake (129B). Alternatively, the small flow of sample gas may be vented after being measured and not returned to the main gas flow.

[0236] Attached to the piping (118) is a flow sensor (104), preferably an ultrasonic volumetric flow meter, which is used to measure how much gas is being burned by the gas burning system (100). The amount of gas being burned by the system is recorded and reported with the information being used as one of the parameters to determine health of the source in cases where source modeling is applied. The desired values in this case are unique to each source and are either known in advance by previous measurement of the source or are determined by measurements made by the system during commissioning. In the case where the values are not known a priori, the electronic control subsystem (111) and the gas measurement subsystem (105) measure these values during the commissioning phase. For example, the flow rate can be gradually increased by the electronic controller subsystem (111) until oxygen is detected in the measured gas stream by the gas measurement subsystem (105), signaling the maximum permissible flow rate of the source without entraining air. The flow sensor (104) is illustrated in line with the main flow but may alternatively be placed on a bypass leg with a calibrated or known flow distribution between the main flow and the bypass. A bypass is generally not preferred, due to the bypass compounding the error of the sensor, however this may be done as a cost-saving measure when a sufficiently high-range flow meter is not available or is prohibitively expensive.

[0237] A pressure sensor (110) reads the gas pressure within the piping (118). The pressure at which complete and stable destruction is achieved is the desired pressure. If pressure is too low, the system will reduce the effective flow area of the system. In the preferred embodiment, this is implemented by reducing the number of open burner manifolds. If the pressure is too low with the number of open manifolds (101) at its minimum, the electronics controller subsystem (111) will close the main valve (113) and prevent flow from escaping undestroyed, while continued gas production in the source increases the to acceptable levels again, at which point gas destruction flow is resumed. The main valve (113) will remain closed until continued gas production in the source increases to acceptable levels, at which point gas destruction is resumed. If the pressure is too great, the system will increase the effective flow area of the system. In the preferred embodiment, this is implemented by increasing the number of open burner manifolds (101). The number of open manifolds (101) will be increased until the pressure falls to a range conducive to complete and stable destruction.

[0238] The particular pressure thresholds which trigger these changes between manifolds are specific to the site and will be configured upon installation and commissioning. For example, a site which is expected to range between 0.5 inch water column and 1.5 inches water column (w.c.) operational pressures, and which has 3 available manifolds may have the following transition points: transition from all valves closed to the first manifold at pressures above 0.5 in w.c., open the second manifold at pressures above 0.8 in w.c., and the third manifold at pressures above 1.2 in w.c. (and close off manifolds in the reverse order). In practice, to protect against unwanted oscillation around the switching threshold, a hysteresis may be applied, i.e. a slight shift in transition point may be configured for opening vs closing a valve, e.g. the third manifold may be opened when pressures first rise above 1.25 in w.c. but not closed until values fall below 1.15 in w.c. Tuning of these particular pressure thresholds which trigger these changes between manifolds are specific to the site and will be configured upon installation and known by those skilled in the art.

[0239] The pressure at which complete and stable destruction is achieved is the desired pressure. For the purposes of gas destruction validation, this is generally achieved by exhaust gas temperature monitoring. In addition, at the time of commissioning, a gas sample may be taken from the exhaust and analyzed by a lab to establish the destruction effectiveness at the given measured temperature. This sampling and analysis may be repeated at regular intervals depending on the requirements of the validating body.

[0240] The data received from the sensors is transmitted to the electronics control subsystem (111) that has been loaded, as described hereinafter, with the desired parameters based on the source gas, environment, and other factors that will be clear to those skilled in the art.

[0241] The above sensors, pressure sensor (110), temperature sensor (119), and the gas concentration sensor subsystem (105), provide information to facilitate optimal burning although in alternate embodiments these may be optional. It should be noted that the order illustrated in the embodiments herein is for example only and the order of sensors are interchangeable unless otherwise noted herein or obvious to one skilled in the art that function will be compromised. For example, the flow sensor (104) must be positioned such that its measurements are not influenced by upstream elements or geometry. An optional flow conditioner can be placed immediately upstream of the flow sensor to guarantee that the measurements will not be influenced by flow disturbances. Gas pressure (110) and temperature sensors (119) are located close to the flow sensor (104) if they are to be used for pressure- or temperature-compensation, though they may fall either upstream or downstream of the flow sensor (104). All sensors may either be directly installed in the pipe or installed in a bypass loop which directs a fraction of the total flow past the sensors. Gas temperature and pressure compensation may alternatively be internally incorporated in the flow sensor (104), or may be absent if not indicated by reporting requirements. Alternatively, the system may use a thermal flux sensor (128) installed in the chimney (125) to directly quantify methane destruction either in addition to or instead of gas flow and methane concentration measurements. This could be useful, for example, in a retrofit where the existing gas piping does not allow for an upstream flow sensor to be fitted.

[0242] For optimal operation in the illustrated example, the gas burner system (100) requires the source gas to be slightly pressurized, for example, to pressures less than 0.5 psi, preferably 0.02-0.5 psi. This can be achieved either by deploying the system on a gas source that is naturally pressurized, or by the addition of a blower (138) to boost the pressure. Additionally, when methane is the target gas, the system requires concentrations above 5% volume in air, and preferably between 40% and 100%. Methane below 5% concentration in air is not combustible, thereby providing the minimum operational value.

[0243] Higher fuel-gas concentration sources are easier to combust and burn hotter. Accordingly, gas concentration is an important process variable for ensuring safe and effective gas destruction by the burner system. The present system is able to operate reliably between 35-100% concentration methane, or other source gas, as long as adequate flow is present. Gas concentration may vary depending on the source e.g. if the gas source is a biological decomposition process, the concentration of source gas such as methane may vary depending on the microbial composition. It may also vary if a leak is present, allowing gases to be diluted by air. The gas concentration sensor (105) continuously monitors the source gas, in this example methane concentration, and the controller subsystem (111) flags if the methane concentration drops below acceptable levels, either for automated shutdown or for operator intervention. In applications where other flammable gases or mixes of gases are burned, these operating limits are adjusted based on the properties of the fuel gas.

[0244] The pressure sensor (110), such as a digital pressure transducer or equivalent is located in the primary feed gas supply piping (118) to the manifolds (101), allowing pressure measurements to feed into the controller subsystem (111) logic for the actuated valves (102, 113), as illustrated in FIG. 10 and described in more detail hereafter.

[0245] The electronic controller subsystem (111) uses the measurements received from the pressure sensor (110) to open or close the appropriate number of electronic valves (102, 113) to control the amount of backpressure (FIG. 12). This allows the gas burner system (100) to function with stable combustion over a larger range of flows than would be the case for a fixed set of manifolds (101) without multiple valves (102, 113). The valves (102, 113) are preferably pneumatically driven, remotely actuatable butterfly valves with a normally closed spring-return configuration. Alternatively, the valves may be actuated by thermopiles located in the flame. Alternative valve control configurations and fail-states are allowable, such as (but not limited to) normally open spring-return valves, or double-acting valves.

[0246] The preferred number of manifolds (101) is four (4), and the preferred number of flow control valves (102), is two (2) plus a master shutoff valve (113), with an optimal arrangement of these components illustrated in FIG. 1. Four (4) manifolds give a variety of flow configurations sufficient to cover a flow turndown ratio (ratio of maximum to minimum flow) of 10:1 or more where turndown ratio is the ratio of maximum to minimum capacity. This matches the seasonal patterns in flow of biogas sources based on winter and summer temperatures and allows for variation due to differences in flammable gas concentrations. Further, four (4) is a useful number because it allows 0, 1, 2, 3, or 4 open manifolds, which can be controlled by 3 valves. As will be obvious to those skilled in the art, the optimal number of manifolds will depend on the site and source characteristics and expected flow variability, with additional or fewer manifolds being required.

[0247] At least one shutoff valve is located upstream of flow control valves (102). Preferably, a main shutoff valve (113) is located along piping (118). This arrangement allows for efficient selection of 0, 1, 2, 3, or 4 manifolds (101), depending on which combination of flow control valves (102) are opened. This arrangement follows binary addition logic and may be extended to greater or fewer manifolds. In this arrangement, at least one igniter (106) must be located adjacent to the manifold (101A) that is solely controlled by the main shutoff valve (113), in order to guarantee combustion is initiated in all startup conditions.

[0248] Alternatively, as illustrated in FIG. 3, an architecture may be used where each piping (159) branch to a manifold (151) is individually controlled by a single valve (152) directly from the source instrumentation plumbing, without a master shutoff upstream of all other valves. Alternatively, instead of or in addition to the use of valve-controlled branches within a flare to control backpressure and flow, additional chimneys (200B) (FIG. 4) may be used under a similar control architecture to further extend the operating range of the device. An example configuration is given in FIG. 4, wherein chimney (200A) contains two controllable branches (201A), two control valves (202A), two flame arresters (216A), and one igniter (206A), allowing for half or full flow capacity of the device. Two additional chimneys (200B), each with their own single control valve (202B), single flame arrester (216B), and igniter (206B), are also included in the system. The monitoring and transfer section takes measurements upstream of the point of flow branching, effectively allowing all flares to act together as a single controllable system with multiple flow modules-in this case, modules are whole flares. In the embodiments disclosed heretofore the modules are manifolds (101, 201) within a flare. This extends the modular flow capacity to additional flares and allows for the same control logic as is described herein for multiple manifolds within the same flare. However, in this embodiment, the ignition logic must be modified so that as additional flares come online, their individual igniters (106) are triggered such that gas is ignited and confirmed to be destroyed. The employment of multiple flares may be with or without separately controllable manifolds within an individual flare. The advantage of this embodiment is increased flexibility to source gas conditions-a much larger range of flows can be successfully destroyed than within a single flare. Additionally, in some applications this modular strategy may have cost advantages in manufacturing and shipping of devices, compared to installation of a single monolithic flare.

[0249] The sensor value input to the control logic within the controller subsystem (111) is preferably a pressure sensor (110) measurement but may alternatively be thermal (e.g. temperature measurements from exhaust/flame temperature sensor (115) in the burner chimney (125), or a flow sensor (104) from the feed gas. If pressure in the pipe is insufficient for effective flow, a blower can be used in the system to control the flow rate of gas going to the flare by speeding up/slowing down the blower. In some circumstances, barometric pressure fluctuations can have a significant influence on the pressure of the system. This is a case in which using flow as the control variable is preferable to pressure, or a gauge pressure signal should be used.

[0250] If sensors other than a pressure sensor are used, appropriate transition setpoints will need to be configured in the control system, specific to the type of gas source. For instance, a gas source that is a large-volume, low-pressure reservoir (e.g. covered biogas lagoon) may display minimal changes in pressure in response to valves being opened or shut, whereas a high-pressure, low-storage volume source may show a comparatively stronger pressure response to valves being opened or closed. Selecting the appropriate control variable (usually pressure or flow) and transition threshold points is therefore site-specific and will be known to those skilled in the art of control system design and gas flow dynamics.

[0251] The gas burner system (100) is controlled by an electronic controller subsystem (111) having at least one processor (170) running a software program. The processor is preferably in the form of microcontroller or set of microcontrollers or a microprocessor. The type of processor used in the electronic controller subsystem will be clear to those skilled in the art and may change with advancements in technology. An overview of the controller subsystem is shown in FIG. 16. A single microcontroller can be used to conduct all process measurements and flare control for a one flare, one source system. If multiple flares, and/or multiple sources are desired, then multiple microcontrollers can be connected together and coordinated by a single host microcontroller which coordinates other device microcontrollers via a wired or wireless network. Alternatively, the flare control and gas measurement subsystems can be run on separate microcontrollers; such an arrangement might be advantageous when the measurement subsystem is located away from the flare system.

[0252] The controller subsystem (111) takes the measurements corresponding to sensor-generated data/values from gas flow sensor (104), pressure sensor (110), source gas temperature (119), gas concentration sensor subsystem (105), and/or exhaust/flame temperature (115) and makes an assessment of the optimal state of the system. Once the assessment is made, system elements are actuated through control subsystem circuits to promote stable functionality of the system. Example actuation of system elements includes control valves (102) and main shut off valve (113) are instructed to open, close, or maintain status quo in order to tune the gas velocity through the nozzles (103) and thereby maintain stable flame. The ability to assess the proper number of manifolds (101) to activate and dynamically adjust, by way of opening or closing valves (102), is valuable as the system is enabled to automatically adjust to fluctuations in gas flow or composition without issues such as flameout, backburning, or poor combustion. The electronic controller subsystem (111) also monitors the ignition sequence, triggering igniters (106) at the appropriate time in order to light the gas burner system (100), or idling the system if successful ignition is not attained. The electronic controller subsystem (111) also monitors safety parameters, for example temperatures of the gas burner system (100) through exhaust/flame temperature sensor (115), gas flow sensor (104), and optionally, presence of oxygen in the gas concentration sensor subsystem (105), and is capable of shutting down the system, stopping the flow of source gas, and/or sending alerts to a remote operator if out-of-bounds conditions are observed.

[0253] This is valuable in protecting the safety of the system and environment and also prevents unchecked release of undesirable gases in the event that flameout does occur. With most currently available flares, uncontrolled release of undesirable gas occurs in the event of a flame out, because these flares do not have the sensor and actuator integration, and algorithmic control documented herein. In cases where the gas source also has physical safety limits, for example, a manure pond where the cover has a maximum allowable pressure, the electronic controller subsystem (111) can take immediate action when a limit is triggered, or depending upon presets within the controller subsystem (111), or model the source behavior to predict when those limits are at risk of violation. Depending upon the presets, the controller can take automated action to alter the operating state of the gas burner system to relieve the risk and preserve the safety of the gas source. The gas burner system (100) may also be shut down at any time by means of a physical emergency stop button, or by a remote operator. The electronic controller subsystem (111) may also be designed to merely pass sensor data and system state via the remote communicator (108). In this embodiment, the analytical functions would be performed by remote computers or cloud computing and not physically located on site.

[0254] As shown in FIG. 5 the illustrated example embodiments use a circular burner enclosure (131) containing 18 nozzles (103) arranged into 4 manifolds (101) each with an entry port (101A). Each nozzle (103) is preferably followed by a converging-diverging housing (112) (FIG. 2) to entrain primary combustion air, and a flame holder device (114) to improve combustion stability The converging-diverging housing (112) and/or the flame holder device (114) may be absent if not required for complete combustion.

[0255] Preferably, one or more electric igniters (106) are placed close to one or more of the nozzles (103), converging-diverging housings (112) or flame holder devices (114) to initiate combustion. Although not essential to the operation of the illustrated embodiment, the converging-diverging housings (112) and flame holder devices (114) serve to stabilize the flame, thereby preventing potential flameout. Additionally, the inclusion of these elements provides more efficient burning of hydrocarbons.

[0256] Flame stability may be aided by the use of a thermal mass device (117), such as a metal slug or rod placed directly in the flame path to reignite the gas in the case of momentary interruption. Typically, with a welded, riveted, or screw-mounted bracket to either the manifold or the burner housing.

[0257] Each igniter (106) is preferably connected to the electronic controller subsystem (111) in order to receive and transmit data to and from the controller subsystem (111), thereby enabling automation. The automation is based on information from an exhaust/flame temperature sensor (115) or other comparable device such flame sense rod, or flame rectification rods and/or flow (104), pressure (110), or exhaust/flame temperature sensor (115) which feed into the electronic control system (111). Through the data received by the controller subsystem (111), the gas is ignited only when gas flow is detected, and exhaust temperature has dropped below a preset temperature threshold indicating lack of combustion.

[0258] All of the sensors within the gas burner system (100) are preferably hardwired but alternatively may be wirelessly connected via a protocol such as Bluetooth. The controller subsystem (111) should be programmed to ensure that the igniters (106) will not spark when a combustion reaction is occurring in the burner enclosure (131), in order to conserve power. Alternatively, the igniters (106) can be set to ignite continuously, or at daily, hourly, or weekly intervals depending on the regularity of the gas source. Whether or not the igniters (106) are connected into the main electronic control system (111) and power source (109) will be dependent upon the source gas and the application. As an alternative to the use of igniters (106), combustion is ignited by a pilot light, continuous or intermittent, fueled by stored gas, either from the flammable gas source, or externally provided propane or other fuel source. The igniters (106) may also be replaced by a continuous or intermittent flame created by one or more wicks in an oil reservoir.

[0259] Care must be taken to protect against accidental flashbacks if the source of the gas contains concentrations of flammable gas and air or oxygen within the combustibility limits of the gas. In the illustrated embodiments, this is addressed by use of a flame arrestor (116), either commercially purchased or fabricated, to protect the components upstream of the flame arrestor (116) from excessive temperatures, ideally while minimizing pressure drop through the flame arrestor (116). Low pressure drop through the flame arrestor (116) is desirable in some applications as it allows operation of the gas burner system (100) with lower source pressures, but it is not essential in cases where the source gas is sufficiently pressurized or can be moved by a blower (138) or pump.

[0260] As pressure is required to keep the gas moving through the system, the source pressure sets what can be referred to as a pressure budget in the system if no blower is present. The combined pressure drop of all the components in the system must not exceed the source pressure at the desired flow rate. Flame arrestors with low pressure drops are available but expensive and may be necessary for sources with low pressure. Alternatively, a pump or blower may be used to boost the pressure of the source, enabling cheaper, higher-pressure-drop components, including flame arrestors, to be used. These are standard fluid design principles.

[0261] The flame arrestor (116) further provides a heat sink so that heat can be conducted away from the bottom of the flame and dissipated to the burner chimney (125) and/or environment. This prevents the upstream combustible gas mix from reaching the autoignition temperature of the flammable components. In alternative embodiments, different sizes or shapes of stainless-steel aggregate, metal foam, or spun metal may be used, primarily for the purpose of changing pressure drop through the system, as well as different sizes of stainless-steel mesh. Alternate high-temperature materials may also be used for all of these components.

Calibration/Recalibration

[0262] Within the monitoring and combustion path of the gas destruction system, the gas concentration sensor subsystem (105) optionally contains recalibration equipment (250, 300) that is used to remotely or automatically recalibrate sensors which may drift out of calibration. This recalibration subsystem increases maintenance intervals while maintaining sensor accuracy and allows for the use of lower-cost sensors which may drift over time compared to a lab-grade state-of-the-art system, without compromising data accuracy. The ability to trigger and complete recalibration-whether automatic, on a schedule, or remotely controlled-enables the practical use of lower-cost sensors without adding operational overhead. As this is applicable to all sensors, the cost savings can be substantial.

[0263] The recalibration equipment is controlled by the electrical controller subsystem as illustrated in FIG. 14 and will be discussed in detail later. Generally, the gas concentration sensor subsystem continuously monitors for sensor drift or a time limit expiration, each of which would trigger action for recalibration. Recalibration action includes closing the process gas valve (266) and opening the first calibration gas valve (251A). When equilibrium is reached, valve (251A) is closed and the second calibration gas valve (251B) is opened. Once equilibrium is achieved, all calibration gas valves (251A and 251B) are closed and the process valve (266) is reopened to return to flow from the source.

[0264] Two examples of a recalibration subsystem are illustrated in FIG. 6 and FIG. 7 and depict the gas concentration sensor subsystem (105) with the optional addition of the auto-recalibration subsystem. When the recalibration component is present, this subsystem serves dual purposes of gas concentration sensing and logging, and recalibration. At minimum, the gas concentration sensor subsystem (105) senses and logs gas concentration for operational decision making and data reporting.

[0265] Alternatively, sensing accuracy may be improved, corrected, or detected to be out of calibration by way of measuring concentrations of other gas species in the source gas and subtracting these to confirm the measurements of the methane or target gas component. Another alternate embodiment could use a substitute reference gas or gas mixture with a known sensor response instead of methane, in order to remove hazardous material shipping restrictions or otherwise reduce cost. Analogous automated calibration processes may be done for other sensors besides the gas concentration sensor, for instance to reset the zero-point of the flow sensor (104) and pressure sensors (110) by isolation from the main process flow through an analogous valve-bypass system.

[0266] Regardless of whether a recalibration system is employed, a sample of gas, as illustrated in FIG. 6 and FIG. 7, is sent from piping (118) to the gas concentration sensor(s) (252, 302) via a small-diameter tubing bypass intake/inlet (259A, 309A) and expelled from the gas concentration sensor subsystem via an outtake/outlet (259B, 309B) to return to the main piping (118) through tubing or to enter the environment. In this normal operation state, the process gas valve (266, 308) is set to pass the source gas, and calibration gas selection valves (251A and 251B) are closed in the case of FIG. 6. The position of the calibration gas selection valve (310) in FIG. 7 is not significant in the normal operation state, as the path is closed at the source gas selection valve (308). Gas flow may be driven passively through the gas composition sensors (252, 302) within the gas concentration sensor subsystem (105) by the pressure of the source gas, or may be driven by a small pump or blower, such as a peristaltic gas metering pump. Calibration gas pressure regulators (265A, 265B, 315A, 315B) are set during commissioning, and are not turned on or off during operation of the system.

[0267] When calibrating the gas concentration sensor (105), the preferred method of remote recalibration is to include cylinders of reference gases (268A, 268B, 318A, 318B), preferably 100% methane (268A, 318A) and 100% N2 (268B, 318B), and electronically-actuated valves (251A, 251B, 310) which allow the sensor (252 and 302) to be isolated from the source gas flow, purged, and exposed to the reference gases. Alternate gas concentrations and mixes may be used, including compressed air or non-compressed ambient air from the environment. The most appropriate gas mixes will be specific to the source application and will be known to those skilled in the art.

[0268] Calibration gas cylinders (268A, 268B, 318A, 318B) are preferably high pressure (between 200 and 1000 psi) cylinders, and therefore likely to require pressure regulators (265A, 265B, 315A, 315B) upstream of the valve (251A, 251B, 310) in order for these valves to function correctly. Gas sent to the sensors (252, 302) within the remote recalibration subsystem (250, 300) preferably passes through a conditioner (253, 303) containing a desiccant or molecular sieve, such as silica bead or equivalent material, either disposable or reusable.

[0269] Passing the source gas through a conditioner (253, 303) improves measurement accuracy by controlling calibration and normal operation conditions. The conditioner is based on the source gas composition. If preliminary survey data on the source indicates that the source gas contains components which can interfere with the sensors used, a conditioner is applied to the gas concentration system (105) sampling pathway to remove such components. The most common purpose of the gas conditioner (253, 303) is to remove water vapor from the source gas so that condensation does not occur on the sensor elements, which may distort their reported values. Water vapor is frequently present in gas from underground sources, agricultural sources, and landfill sources.

[0270] A heater (260, 306) can be incorporated to improve measurement accuracy by controlling calibration conditions. The conditioner (253, 303) may also use a chemical scrubber media, if necessary, in addition to or in place of the desiccant, to remove trace components of the gas stream to improve measurement accuracy or inhibit corrosion (e.g. H2S, other hydrocarbons). The heater (260, 306) in the desiccant chamber, if present, may be used to periodically bake out moisture from a reusable desiccant, effectively lengthening the useful life of the material. This is accomplished by heating the desiccant material to release and remove stored moisture, thereby increasing the capacity of the desiccant to absorb moisture in the future.

[0271] When used for bakeout of moisture, the heater (260, 306) can be run on a schedule based on expected saturation time. Alternatively, gas concentration sensor (252, 302) drift can be measured by the controller subsystem (111), and the heater (260, 306) can be run when the drift exceeds predetermined bounds. To determine the heating time, the desiccant manufacturer specifies a desaturation profile including time and temperature which is specific to the desiccant used, the specifications of which would be entered, and/or updated as necessary, into the controller subsystem (111). Alternatively, the heating time can be determined by gas concentration sensor (252, 302) readings used to detect the change in readout accompanying desaturation of the desiccant material, or by a humidity sensor integrated into the gas concentration sensor subsystem. If this mode is employed, sensor measurements would be paused while the heater increases temperatures to cause moisture to escape the desiccant and flow into the effluent stream from the gas sensing system. After the bake-out period is complete, normal operations are resumed and gas concentration sensor (252, 302) values are read as normal.

[0272] As depicted in FIG. 7, two 3-way valves (308, 310) are used to pass calibration gas to the gas concentration sensors (302). The gas concentration shutoff sensor valve (308) selects between source gas (normal mode) being received via pipe (309A) and calibration gas (calibration mode) to receive calibration gas through pipe (309D). The calibration gas selection valve (310) selects between calibration gas reservoirs, depicted in this example as compressed CH.sub.4 (318A) and N.sub.2 (318B). Valves (308, 310) may alternatively be pneumatically actuated, when connected to the microcontroller (134) and/or controller subsystem (111), or manual.

[0273] Regardless of which valve configuration is used (FIG. 6 or FIG. 7), the pressure regulators (265A, 265B, 315A, 315B) must drop the pressure from that of the high pressure cylinder (usually in the range of 500 psi) to a level which the calibration gas selection valve (310) or cylinder shutoff valves (251A, 251B) can effectively seal completely, for example 20 psi, depending upon the valve. High pressure gas fittings must be installed in piping runs expected to see high pressure and in which leaks are not tolerable, for instance between the regulators (265A, 265B, 315A, 315B) and the calibration gas selection valve (310), or cylinder shutoff valves (251A, 251B). Both the regulators (265A, 265B, 315A, 315B) and calibration gas selection valve (310) or cylinder shutoff valves (251A, 251B) must be tested for long-term leaks in their respective pressure ranges of operation.

[0274] Regardless of whether an auto-calibration system is employed, the gas concentration sensing subsystem (250, 300) pulls source gas in through a pipe (259A, 309A) where it passes through the gas conditioner (253, 303) and optional heater (306, 260). The gas then leaves the gas conditioner (253, 303) through a pipe (259B, 309B) to the gas concentration sensor (252, 302). The gas then leaves the gas concentration substystem through an outlet to either rejoin the source gas in pipe (118) or is expelled to the environment.

[0275] After measurement, the gas may be returned downstream to the gas flow via small-diameter tubing or vented to the environment. The decision to vent or return to the main flow is based on source pressure and acceptable site requirements. If the source pressure is sufficient to provide adequate flow against the backpressure of a main flow return line, then it can be implemented as a main flow return. If it cannot, venting is used.

[0276] The gas concentration sensor (252, 302), gas conditioner (253, 303), calibration control valve (251A, 251B), calibration gas selection valve (310), and process gas valve (266, 308) are preferably contained in a weatherproof enclosure (254, 304).

[0277] Alternatively these components may be unhoused or located indoors. High pressure cylinders (268A, 268B, 318A, 318B) are preferred in order to maximize capacity, however rigorous leak testing is required on high-pressure assemblies within the recalibration system (250, 300) in order to ensure that calibration gases do not leak over time, diminishing the opportunity for future calibrations. Reliable component selection and sourcing is important for these parts and will be known to those skilled in the art.

[0278] One challenge to the design of the autocalibrator system is the need to store high pressure gas for long periods of time and be remotely operated as such systems are prone to leak. An auto calibrator system attains max utility if it can be installed without servicing for at least 6 months and up to several years, and even small leaks will drain the cylinders over such long storage times. To accomplish this, cylinders (268A, 268B, 318A, 318B) must be fitted with a tested leak-proof high-pressure regulator (265A, 265B, 315A, 315B), upstream of a shutoff valve (251A, 251B, 315A, 315B). Leak testing of the regulators (265A, 265B, 315A, 315B) is done at the time of assembly, and consists of pressurizing the assembled plumbing section and monitoring the trapped volume of gas or liquid over a prolonged period of time, for instance, 12 hours, for decreases in pressure that can be attributed to leaks. The functional objective of selectively isolating the process gas flow, and exposing the sensors to calibration gases may also be accomplished through the use of other flow configurations, such as 3-way solenoid valves, as well as other types of valves and valve configurations such as ball, needle, or gate valves, and direct-acting or air-pilot pneumatic solenoid valves with or without spring-return. Some configurations of three-way valves may allow one fewer valve to be used, saving cost.

[0279] The auto-calibration systems (250) and (300) described heretofore are controlled by the auto-calibration controller subsystems (264, 305) either separate (264, 305) or in communication with the main electronic controller subsystem (111), and is primarily used for calibration of gas concentration sensors and continuous collection of concentration sensing data. The auto-calibration microcontroller optionally contains a separate communicator (267, 307). The controller (111) may be configured to automatically detect the need for calibration and/or trigger calibration based on the drift in sensor (252, 302) measured values outside their expected range or expiration of a pre-determined time period. Calibration may also be triggered manually by a remote or on-site operator. The bleed off to the gas concentration sensor subsystem is continual during normal operation but may be interrupted during recalibration.

[0280] As stated heretofore calibration is called for by the control system based on either a schedule or if readings drift outside a range of expected behavior, or if manually triggered by an operator. The gas sensing control system (264, 305) monitors and detects the need for calibration. The auto calibration control system (264, 305) will isolate the gas sensing loop from the main process flow, by way of closing the process gas valve (266, 308), then sequentially opening calibration gas valves (251a, 251b, 310) to expose the sensor loop to calibration gases for zero and/or span calibration, as needed.

[0281] Any linear fit calibration requires at a minimum two points of reference at different known values. Zero calibration determines the sensor reading relative to a gas with zero content of the target gas. Span calibration determines the sensor reading at a known non-zero content of the target gas. Zero and Span calibration are industry terms and will be known to a typical practitioner of the art. Two-point calibration is not limited to linear fit and can provide corrections to higher-order formulas if a non-linear sensor model is used.

[0282] For each calibration gas, the system either allows a predetermined purge time to pass or waits for a stable value from gas concentration sensors, in order to determine the system has reached equilibrium.

[0283] A stable value is a value that is close to unchanging with time. It can be of any value but is considered stable when it has not changed by, for example, more than one percentage point in 30 seconds. At this point, the sensor is considered equilibrated, and the reading may be used as a calibration point. At this point, all sensor values (including optional process condition values such as temperature, pressure, and humidity) are recorded as calibration data by the microcontroller and software. After calibration mode is complete, the control system isolates the calibration gases (251A, 251B, 310) and returns the process gas valve (266, 308) to an open state to flow process gas through the gas sensing loop. Further details of the control sequence are given in FIG. 11.

[0284] The preferred embodiment of the gas burner system (100) also contains a communicator (108), which preferably consists of a wireless transmitter that sends out the sensor data that is needed to calculate how much gas has been burned and when combustion has occurred Although this can be stored within the system and viewed upon site visitation, it is preferable that this data can be collected and delivered remotely without human intervention. The communicator allows the system to be deployed and monitored without needing physical intervention by an operator. Equipment such as antennas are preferably used to transmit the data to terrestrial cellular networks, or to satellites in the event no appropriate cellular network is available. Alternatively, the wireless communicator may be a Bluetooth or other short range wireless protocol (e.g. LoRa) device to enable transmission of data from the system to a base station that is nearby. Preferably, data is stored local to the system, as well as being transmitted wirelessly. In the event that the data connection is temporarily lost, data can be temporarily stored while the outage is ongoing and forwarded when the connection is restored. Alternatively, the data may be solely stored within the controller subsystem (111) and gathered by having a person physically go to the system to retrieve data. In an alternate embodiment of the invention, the data is transmitted over a wired connection. Remote communication of the data allows alarms to be configured to alert operators of off-normal conditions, such as changes to flow rate, temperatures, gas concentration, or system auto-shutdown events. These alerts may generate text messages or email to operators and allow for more efficient and effective system operation.

[0285] Data from the device is preferably transmitted wirelessly through the communicator (108) at least every 15 minutes to a main database system for analysis. Data may be analyzed by a human operator or compared to a preprogrammed algorithm to make operational decisions and may also be used for reporting statistics on the total gas mitigation. For these purposes an operator or algorithm within the main database system may use sensor values to make corrections such as temperature- or pressure-correcting flow measurements to produce more accurate results. Sensors may already include this analytical capability (for example, a flow meter which internally provides temperature-compensated measurements), or may provide very simple outputs which an operator or algorithm must convert into meaningful values (for example, a gas concentration sensor that reports a raw millivolt or milliamp signal and must be converted to a meaningful concentration value). For sensors which provide a raw value and must be interpreted to produce a meaningful result, a known calibration point is preferably used to increase the accuracy of the result. For example, to calibrate a gas concentration sensor, sensor values are recorded while the sensor is exposed to a zero gas, i.e. a reference gas containing none of the target species, and a span gas, i.e. a certified reference containing a known concentration of the target species. These gases may be pressurized or may be provided at ambient pressure. If environmental corrections are to be performed on the resulting sensor values (e.g. temperature-, pressure-, or humidity-compensation), these parameters are also recorded for the calibration gases at the time of calibration, then also monitored and recorded during normal operations. These calibration values are used to interpret raw sensor outputs into an accurate measurement during operations until recalibration is required, usually annually. Regardless of the sampling interval and data transmission interval, processed data is preferably batched to 15-minute intervals for reporting purposes, and may be further summarized hourly, daily, monthly, quarterly, or yearly.

[0286] An alternate embodiment of a flame-arrestor device (350) is illustrated in FIG. 8, using water (351) or another non-flammable liquid to provide a barrier against propagation of flame upstream. This is especially convenient for aqueous methane sources. In this embodiment, a chamber (352) is partially full of liquid, with an air pocket (355) above the water level and a source gas pipe (353) extending through the air pocket (355) and into the liquid (351) level. The source gas exits the source gas pipe (353) into the liquid (351) where it is then allowed to bubble up from below the water into the air pocket (353) accumulating above the liquid surface and flowing into the combustor through an exit pipe (354). This prevents flammable gas from having a complete, uninterrupted path to the source. If this embodiment of a flame arrestor device (350) is employed in the gas burner system (100), it takes the place of a pre-manufactured flame arrestor (116) shown in FIG. 1 and is located between the main shutoff valve (113) and control valves (102) and connected to the piping (118). When replacing the flame arrester (216) of FIG. 4 it would be placed after the pressure sensor (110). In most applications the source gas pressure will be sufficient to force the gas through the source gas pipe (353) and into liquid (351). In any applications where the source gas pressure is not sufficient, a small fan can be used.

[0287] In an alternate embodiment the burner system (370), illustrated in FIG. 9, forced drafting is used to burn unpressurized sources of methane, which have a concentration of methane, or other gas, greater than 5%, or applicable burn concentration. In this embodiment, flammable gas, entrained air, and other non-flammable parts of the collected gas are directed to the burner (371). This is accomplished by a combination of forced flow through the use of a fan or blower (372) which pulls gas directly from the source, and natural convection, through the use of the thermal drafting of a chimney (373). The use of a fan may be necessary in some implementations if chimney updraft is not sufficient to provide driving flow, or to mix sufficient oxygen into the flow for combustion. In this embodiment, the requirement to accommodate a large range of flow is accomplished by modulation of the fan speed to maintain optimal concentration ratios for combustion. As noted, hereto, for this example includes a flame arrestor (374), pressure sensor (375), temperature sensor (376), a control system (377), igniter and communicator (379).

[0288] This modification to the control system for this alternate embodiment is illustrated in FIG. 13. In this embodiment, the flame arrestor (374) is integrated directly into the burner nozzle, which causes flame to sit on the flame arrestor top surface. In this embodiment, the chimney (373) is modified to allow additional air to be drafted directly downstream of the burner nozzle. This embodiment also includes one or more sensors (305, 306) for the purposes of documenting gas flow and modulating controllers. This embodiment, as with the embodiment of FIG. 1, also contains a controller (377), one or more electronic igniters (378), sensor data acquisition system, and communications (379).

[0289] The preferred embodiment of the invention destroys methane gas but alternatively may be used to destroy other combustible or non-combustible gases such as nitrous oxide. This may require changes to the burner nozzle diameter according to changes in the gas density, and in some cases may require the addition of fuel gas to the gas source.

[0290] Any of the disclosed embodiments may optionally include storage tanks to enable storage of gas. This may be useful if the system is to be operated in a batch configuration, whereby gas is accumulated until a sufficient volume is available to combust, allowing for periodic stable combustion of otherwise intermittent or low-flow sources. The storage tanks may be constructed of sheet metal, flexible or rigid plastic, composite materials, or rubber. The storage tanks may be attached to the source via a tee pipe fitting to provide a path for the gas to flow into the storage tanks as well as to the burner enclosure (131) or may be integrated directly into the source piping. The storage tanks may have a pressure regulating valve to slowly allow gas to flow out of the tanks. The slow flow of gas from the storage tanks could potentially supply a pilot light to eliminate power for re-ignition. The storage can also take the form of the source itself, for example, a gas-producing lagoon covered with a plastic film which may expand as gas inventory is accumulated, or another example, an underground mine cavity with a drainage well, which may build pressure when not allowed to flow. In this way, the source itself may be treated as an accumulating reservoir for the purposes of batch operation, whereby the source is periodically closed off in order to build pressure or volume for later destruction.

[0291] The embodiments illustrated here are static, bolted to a stable structure and, where applicable, also contain guy lines for stability (140). The invention may alternatively be mobile and may optionally include a GPS tracker so that the position of the system can be found via a wireless communicator. In aquatic environments, tracking the system's position allows the operator to see if the system has drifted from its initial location. For a mobile unit, bolts to a stable structure or guylines may not be present, or they may connect to a skid or trailer intended to be moved, rather than to a fixed structure. Gas quick disconnects may be used in this configuration to facilitate ease of connection to sources.

[0292] In some applications the gas burner system (100) components are lightweight for ease of transportation into rural areas which large vehicles or vessels cannot access. Alternative, especially in harsh climates, the components would need to be heavier and more durable than the lightweight components.

Control System

[0293] What follows is an example of an electrical control subsystem (111) to operate the gas destruction system of the present invention, an overview of which is illustrated in FIG. 16. The main objectives of this subsystem are to monitor, report data, start, control, and stop the system to achieve safe and reliable operation in a wide range of gas source and environmental conditions with minimal operator intervention.

[0294] The gas destruction system, hereafter described in example as a gas combusting or burner device, is controlled by an electronic controller subsystem (111). An overview of how the controller subsystem interacts with the burner device within the destruction system is illustrated in FIG. 16. The electronic controller subsystem (111) is located locally with the burner system and configured optionally to connect to an external remote electronic device (180) such as a remote computer, mobile device, or operating sub-station. The electronic controller subsystem includes circuits (172) configured to control parts of the burner system with at least one microprocessor (170) running a computer program (174) in communication with the circuits to operate the burner system. The microprocessor (170) receives data (176) for analysis from the one or more sensors previously described. For example, each valve (190) of the burner system is actuated by an actuator (178) and corresponding circuit (172) that receives instructions from the microprocessor (170) after evaluation of sensor data (176) received.

[0295] As previously set forth, the burner system includes sensors for monitoring system variables including but not limited to pressure, flow, gas concentration, gas temperature, and flame/exhaust temperature. While the exact combination of sensors used may vary depending on the substance being combusted and the environment in which the system is used, pressure is typically the preferred controlling process variable. Each sensor employed generates values that are fed into the control logic of the microprocessor which analyzes the information, determines next steps, and triggers action responses in elements (190) of the burner system as needed to control functionality and maintain stable combustion. Sensor-generated values can also be stored in a local (182) or remote (184) storage database in communication with the electronic controller subsystem (111) and transmitted to the remote external electronic device (180).

[0296] Process variables are measured continuously (408) by sensors located throughout the burner system. Process variables include pressure, flow, gas concentration, gas temperature, flame temperature, and thermal flux. Other process variables may be identified and measured by those skilled in the art depending on the use and environment of the burner system. Continuous measurement means the electronic controller repeatedly requests the most recent measurement from every sensor in the system. In preferred embodiments of the example system, it takes approximately 1.5 seconds to query everything in the system though this rate may vary system to system. These sensor-generated values are stored in at least the local storage database (memory) and are used to operate the burner system and conduct safety checks. Such values may also be transmitted via the communication link (108) to a remote database. Measuring process variables (408) is significant in controlling the elements of the burner system in order to broaden/extend the range of operating points over which the burner system can operate reliably.

[0297] The software of the electrical control subsystem is a state machine with three states: idle (401), ignition (402), and burn (403). The state machine is illustrated in FIG. 10. Each state of the state machine consists of entry actions (414a, 414b, and 414c), an operating loop (415a, 415b, and 415c), and exit actions (418a, 418b, and 418c). The system begins in the idle state (401), during which it loads parameters and monitors system sensors. Upon detection of a trigger to transition into the ignition state (402), which can be automatic or manual, the electronic control subsystem first executes the idle state exit actions (418a), then transitions to the ignition state (402) and executes the ignition state entry actions (414b). The system then enters the operating loop (415b) of the ignition state, which runs until another state transition is triggered. From the ignition state, action can be triggered to transition to the burn state (403) if successful ignition is detected or to the idle state if successful ignition is not detected within a prescribed time. In either case, the ignition state exit actions (418b) are executed before the transition is carried out. If entering the burn state (403), the burn state entry actions (414c) are executed, followed by the operating loop (415c) of the burn state. If entering the idle state (401), the idle state entry actions (414a) are executed, followed by the operating loop (415a) of the idle state. A safety check (404) is performed continuously during the burn state (403), and if unsafe conditions are detected, the system triggers a return to the idle state (401), executing the burn state exit actions (418c) and the idle state entry actions (414a). A detailed description of each of these states, including example values and scenarios, is provided in the following paragraphs.

[0298] On each operating loop (415a, 415, and 415c) of the state machine, all of the sensors are read and their values updated in the memory of the control software. These values are used by the state machine to act on the system, as well as stored and transmitted for reporting via the communication link (108).

[0299] When the system first starts up, it enters idle state (401). In the idle state (401) all valves are closed and igniters not energized. Upon entry to the idle state (401), idle state entry actions (414a) are executed, and process variables are consistently monitored (408). Example idle state entry actions (414a) include loading parameters (410) necessary for operation of the burner system, configuring instruments (412) of the burner system, notifying system operators via communication link (108) of entry into idle state (401), closing all valves, and confirming blowers are turned off. Required idle entry actions (414a) for a particular burner system will be known to those skilled in the art. The electronic control subsystem remains in the idle state until an exit from idle is triggered, such as detected conditions for ignition or an external command to transition to the ignition state.

[0300] Any data or information required by the control subsystem during the idle state can be initially loaded directly by human operators at the burn system site or can be communicated from an external electronic device. Once information is initially loaded, subsequent loops of the idle state automatically load updates to these parameters when required.

[0301] Example system parameters (410) loaded during idle state (401) include variable thresholds, safe bounds for sensor readings during the burn state, telemetry reporting frequency, presence/absence of a blower motor, desired operating speed of the blower motor during the ignition state, and desired operating speed of the blower during the burn state. Note this is not an exhaustive list of parameters (410), and parameters will be clear to those installing and operating a particular burner for a particular use and environment. Parameters (410) can depend on the burner system site while others can be a matter of reporting requirements. For example, California carbon market reporting requirements state telemetry data must be reported at least every 15 minutes, so to ensure compliance and guard against the possibility of a lost telemetry message, the system can be set to report every 4 minutes. Parameters (410) are also informed by the instrumentation that is attached to the burner system and used in converting analog voltages/currents into engineering values (e.g. degrees C., cubic feet of gas per minute, psi). For example, a small flare site might have a 0-25 SCFM flow meter installed, whereas a larger site might have a 0-200 SCFM flow meter installed. Either can be used by the system but the flow meter span parameter must be set appropriately.

[0302] Instrument configuration (412) during the idle state involves loading appropriate data memory to allow appropriate conversion of analog signals to digital format. Most instruments do not return measurements in appropriate engineering units. For example, the gas pressure, temperature, and flow instruments may send an analog current signal from the instrument to the controller. During initialization in the idle state, the electronic control subsystem loads appropriate coefficients from non-volatile memory that allow it to appropriately convert a 16.6 mA current signal from the flow meter into a measurement of flow with appropriate units. Necessary instrument configuration (412) will be clear to those skilled in the art and appropriate data can be entered as needed.

[0303] When a trigger to exit the idle state (401) is detected, the system will execute idle state exit actions (418a), then transition to the ignition state (402). Example triggers for exiting the idle state include automatically detected sensor conditions for ignition, manual operator command to ignition state, or an external call for ignition received via the communication link (108). For example, such a trigger could be that an inlet pressure reading from sensor (110) that is appropriate for the burner system use/environment indicates that a sufficient amount of gas is available in the gas source for operation of the burner system. The electronic subsystem is always monitoring the pressure behind the closed inlet valve as an indication of the presence of gas. Whether the ignition state is initiated by a human operator or automatically will be determined by those skilled in the art at burner system site. Human initiation does have the added value of being able to verify site safety via remote cameras, though it is possible for such safety to be monitored by other means, including by the safety check subroutine of the system software.

[0304] When the ignition state is entered, the system executes the ignition state entry actions (414b). For example, entry events (414b) for the ignition state typically include opening the main shutoff valve (113), powering igniters (106), and starting the ignition timer (420). Further, entry events (414b) may also include commanding a gas blower, if one is present, to operate at ignition speed. The gas blower is powered by a variable frequency drive (VFD) that allows control of the speed of the blower motor and, by extension, the flow rate of gas within the burner system. One of the configuration parameters (410) loaded during the idle state can include the speed at which the blower should run while the control subsystem is in the ignition state. For example, in a preferred embodiment, the blower runs at 10-25% of rated system capacity during ignition. Different sized burner systems are required depending on the system use and environment, and the rated system capacity will necessarily be different for different sized systems; but 10-25% of that rated capacity creates a stable ignition condition.

[0305] Once ignition state entry events (414b) are complete, the controller subsystem enters the loop (415b) of the ignition state, wherein it checks combustion at the igniter (106) using temperature sensors reading exhaust gas temperature (405) and temperature change rate (406), as well as possible ignition timer timeout (407). Gas temperatures are monitored at multiple locations within the burner device including but not limited to the gas intake pipe and the chimney. While the gas exhaust temperature threshold is configurable depending on the use and environment of the burner system, a gas exhaust temperature reading of about 200 C or greater is typically indicative of combustion at the igniter and is the default threshold gas exhaust temperature. While the burner system operates at gas exhaust temperatures up to about 1000 C, a default gas exhaust temperature of 200 C is considered a temperature threshold that is unlikely to result purely from environmental conditions such as ambient air temperature or solar heating and therefore is a useful indication that combustion has been successfully attained. The gas temperature rate (406) is measured from the gas temperature reading detected at ignition state entry. A temperature rate increase of 20 C from ignition state entry temperature within the 120 s timeout is indicative of combustion at the igniter. Solar heating can raise the temperature of the burner device by no more than 20 C within 120 seconds; accordingly, any temperature increase greater than a 20 C increment is likely from combustion and not external factors. If a gas exhaust temperature reading of greater than 200 C or a temperature rate increase of greater than 20C is detected, the electronic controller subsystem moves to the burn state (403).

[0306] On each cycle of the ignition state (415b), if the electronic control subsystem does not detect ignition, the status of ignition timer is checked to determine if a timeout (407) has occurred. The ignition timer is preferably a software timer started upon entry (414b) to ignition state and is a safety mechanism that prevents the system from attempting unsuccessful ignition attempts for extended periods of time. The ignition state is dangerous because flammable gas is flowing but combustion has not yet necessarily been achieved, presenting a potential explosion hazard if prolonged. A timeout (407) occurs when the ignition timer expires without detecting ignition. The electronic controller subsystem stays in the ignition state loop (415b) continuously until either a timeout (407) expires or until the system moves to the burn state (403). The example timeout setting of about 120 s is a reasonable length of time. A reasonable value for timeout is defined by the volume of gas that might need to be purged from the system before ignition can occur and will be determined by one skilled in the art with knowledge of the installation site. For example, if the piping that exists between the igniter and the main shutoff valve for a particular burner device has a total volume of 50 cubic feet, and the pump is operating at 50 SCFM it is thus anticipated to take a minimum of one minute to fully purge the piping once the valve has been opened. Thus, excessive ignition time is driven more by the total internal volume of the pipe and the speed at which the gas is being pumped. The gas destruction system of the present invention seeks to avoid emitting excessive gas out of the burner device without it being ignited. If the electronic combustion system is not working properly and only making intermittent sparks, it would be dangerous to allow flammable gas to continue venting from the burner device, which could result in an energetic ignition.

[0307] In the ignition state, if a timeout is reached without detecting ignition, the system will exit the ignition state (402) and return to the idle state (401). Conversely, if gas exhaust temperatures rise above a threshold gas exhaust temperature or temperature rate the system successfully moves from the ignition to burn state thus exiting the ignition state loop (402) and entering the burn state (403). Upon exit of the ignition state (402), the ignition state exit actions (418b) are carried out, including, for example, notifying the system operator via communication link (108) of its exit out of the ignition state.

[0308] If neither the exhaust gas temperature threshold nor the temperature rate is met and an ignition state timeout has not occurred, the electronic subsystem continues in the ignition state loop (415b) and the burner control law (409) runs to maintain conditions within the burner that promote stable ignition by actuating system elements. For example, the burner control law measures the flow characteristics of the gas (408) to determine and trigger appropriate valve adjustments in the system (409) to promote stable ignition.

[0309] The burner control law (409) is illustrated in detail in FIG. 12 with the process variable being pressure. The current state (490) of process variables (in this case pressure) is compared to the pressure value threshold loaded into the electronic control subsystem. If the current state pressure is greater than the pressure threshold (491), an increment state change (492) is made to open an additional valve, thereby relieving pressure and creating more area for gas flow. Each increment state represents moving from the current state to the next highest state which results in the smallest possible increase in total flow area for the system. For a fixed flow, opening more flow area will decrease the system pressure. The electronic subsystem then returns to monitoring the pressure variable. If the variable is in an acceptable range, the system loops back to the monitoring state. If the pressure variable is below the operating threshold (493), the system makes a decrement state change (494) to close a valve, then returns to monitoring the process variable. Each decrement state represents a reduction in total flow area available to the flare, and for a fixed flow, decrementing the flare state will increase the system pressure. A state table (495) in FIG. 12 provides example process variable thresholds and illustrates the binary addition logic of the flare valves.

[0310] Process variable thresholds vary based on site conditions and setup, for example, concentration of methane at the flare site, size of the orifice from which the gas originates in the flare. These thresholds exist as parameters within the electronic control subsystem and thus can be changed locally or remotely at runtime. Gas pressure is preferably the controlling process variable of the burner system, but it may also or alternatively be temperature, flow, gas concentration, or another monitored variable. If the pressure inside a pipe is higher than the ambient pressure (and the valves are open), gas will flow out from the pipe and into the flare to be combusted. The amount of flow coming out of the flare is dictated entirely by the amount of pressure, and the size and number of orifices through which the gas can flow. For a given pressure differential and a given combined orifice flow area, one can expect a certain amount of flow. In this example, pressure is especially important when dealing with covered manure systems, as excess pressure can damage the cover which is used for gas collection. For example, in a manure pond having a cover with a maximum allowable pressure of 1.5 in. H2O under the cover and a fixed orifice flow area, the pressure-flow relationship of the system is thus also fixed, and an increase in gas production can lead to a dangerous buildup of pressure. Conversely, insufficient production can lead to insufficient pressure and extinguishing of the burner. The system described herein employs an electronic control subsystem to vary the pressure-flow relationship to compensate for changes in the gas source or environmental conditions, thus significantly increasing the range of conditions under which the system can operate safely and reliably and reducing the amount of operator interaction required to do so.

[0311] Once stable ignition is detected, the electronic control subsystem (400) moves to the burn state (403). Upon entry to the burn state, the electronic control subsystem executes the burn state entry actions (414c), for example, notifying operators of entry into the burn state via communication link (108), and commanding the blower to the run speed specified in the system parameters. For example, sometimes the gas destruction system needs to run at a different flow rate during the burn state compared to the ignition state. Thus, the blower is commanded to run at a new target frequency and/or speed and the VFD maintains configured frequency/speed. This frequency/speed may be later updated while the system is running. Run speed will differ depending on the burner device's use and environment. The run speed should not exceed the maximum capacity of the flare (e.g. don't set the run speed to 150 SCFM for a flare rated as 100 SCFM). Beyond that, run speed is matched to the gas production rate of the source (covered manure pond, underground coal mine, etc.) so as to allow steady state operation. If the pump speed exceeds the production rate of the source, then the source will be drawn down, possibly to zero or negative pressure (relative to ambient pressure). If the run speed is set below the production rate, then gas will accumulate in the source, and pressures will begin to rise.

[0312] Once burn state entry events (414c) are complete, the controller subsystem continues executing the burn state loop (415c), using exhaust gas temperature (405) checks to verify that the system is currently burning, and if not, returns to the idle state (401). Provided the system determines that it is burning, the system continues by monitoring process variables (408) and comparing them to an operating threshold, making changes to the valve state to maintain the process variable within a desired range (409) to promote complete gas destruction and safe operation, according to burner control law (409) described in FIG. 12. Preferably, the controlling process variable is pressure, but may also or alternatively be temperature, flow, gas concentration, or another monitored parameter. The system continues in the burn state until exit events (418c) are triggered.

[0313] In the burn state, the system continuously monitors safety parameters (404), monitoring for example, but not limited to: presence of oxygen in the gas source (431); acceptable temperature (434), concentration (432), and pressure (433) limits of the equipment; or an operator call for idle, either remotely or via physical Emergency-Stop button. If monitored values are within safe bounds, the system is allowed to continue normally. If any of these safety parameters are outside acceptable limits, a burn state exit event is immediately triggered, and the system exits the burn state (403) and returns to the idle state (401). A detailed illustration of the safety check (404) is provided in FIG. 11.

[0314] When an exit event is triggered, the electronic control subsystem executes burn state exit actions (418c), for example, notifying operators over communication link (108) that it has exited the burn state, closing all valves, and shutting down the blower. The system then enters the idle state (401), executing idle state entry actions, rendering the system safe and halting gas flow.

[0315] FIG. 13 depicts a closed-loop control block diagram for use with the blower implementation of the flare. The alternate embodiment of the invention using a blower is common for sources with very low head pressure, such as surface seeps on ponds. The set point (450) represents the desired value or target for the system's output, for example cover and pond (454) pressure, or system flow rate. The error (451) represents the difference between the set point (450) and the feedback signal (457). The error (451) is calculated by subtracting the feedback from the set point. The error signal indicates how far the system's output is from the desired value. The Control Law (452) contains the logic or algorithm that determines the necessary adjustments to the system based on the error (451). The specific control law used (e.g., proportional, integral, derivative-PID) depends on the system's characteristics and requirements, and can be reasonably designed by those practiced in the art. The blower (453) is a variable speed blower which can adjust the flow rate based on the output of the control law (452). The Plant (454) represents the actual system being controlled, in this case, it's a cover and pond. The sensor block (455) represents the various sensors that are used to measure the current state of the system and provide feedback. Examples of sensors commonly used in pond and cover systems include, methane concentration, reservoir (pond+cover) pressure, flow rate, gas temperature, oxygen concentration, and hydrogen sulfide concentration. These sensors provide crucial information about the state of the system, allowing the control system to make informed adjustments to the actuator, in this case the blower (453). The state estimator (456) uses the sensor readings (455) to estimate the internal state of the plant (454). This is particularly useful when not all states are directly observable, sensor noise is present, or the system is subject to significant external disturbances. Common external disturbances for cover and pond systems include wind, solar heating, pond draining/filling etc. The state estimator provides a more accurate and reliable representation of the system's condition. The feedback (457) represents the signal that is fed back from the state estimator to the error calculation. It provides the control system with information about the actual output of the system, enabling it to compare it to the set point.

Auto-Calibration Subsystem Control

[0316] As previously described, the gas concentration sensor can include an optional auto-recalibration system. The objective of auto-recalibration is to reduce the amount of operator involvement required to keep the system within acceptable calibration bounds, and to increase the proportion of run time operating within acceptable calibration bounds, which may be required in certain circumstances for certification and validation purposes.

[0317] The controller may be configured to automatically detect the need for calibration based on drift in measured sensor-generated values, expiration of a pre-determined recalibration time period, or human operator instruction.

[0318] The preferred control sequence (500) for the auto-calibration electronic controller subsystem (264) illustrated in FIG. 14 begins in the normal operation state (501). This is the operating state of the gas concentration sensor subsystem (105) when calibration is not called for and consists of monitoring sensor values of process variables. For example, gas concentration, pressure, temperature, and humidity in the gas sensing loop are measured and these values are reported back to the electronic controller subsystem (111). During this monitoring process, the gas concentration sensor subsystem continuously monitors for sensor drift (502) or the time limit expiration, each of which would trigger action for recalibration. If no calibration is called for, the system stays in normal operation (501) with the process gas valve (266) open. If a calibration is called for, the subsystem moves to the calibration state (503). From this state, instructions are sent via a circuit to actuate closing of the process gas valve (266) and the opening (504) of the first calibration gas valve (251A). Next the gas concentration sensor subsystem checks for equilibrium, either through attainment of stable values in sensor readings or by pre-determined sensor stabilization timeout (505). The gas concentration sensor subsystem stays in this loop (504-505) until equilibrium is reached and calibration values for the first gas can be recorded. At this point, instructions are sent via a circuit to actuate (506) closing the first calibration gas valve (251A) and opening the second calibration gas valve (251B). Next the gas concentration sensor subsystem again checks for equilibrium, either through attainment of stable values in sensor readings or by pre-determined sensor stabilization timeout (507). Once equilibrium is attained, calibration values for this second gas can be recorded and the subsystem closes all calibration gas valves (251A and 251B) and reopens the process gas valve (266) to return to flow from the source (508). The gas concentration sensor subsystem then returns to the normal operation state (501) where the cycle of monitoring begins again. While FIG. 14 is an explanatory overview of the process, the implementation details will be known to those skilled in the art.

[0319] Alternatively, the sensors may be manually recalibrated by field personnel as needed.

Gas Characterization and Source Modeling Aware Control

[0320] The disclosed gas destruction system may optionally include characterizing and modelling of the gas source as part of the system's control algorithm. The purpose of this is for the electronic control subsystem to make decisions about the operational control of the gas destruction system based on informed expectations about the behavior of the source, prediction (552) about its future behavior and response to control changes in the system. These loaded parameters can be modified by the operator or by the electronic control subsystem itself during a learning phase (551) where the system operating point, for example, the number of open valves, aperture size of the air intake or the speed of the blower for the source gas is varied and the resulting source behavior is recorded and applied to the parameters.

[0321] Source characteristics calculated from known science, inferred experimentally (551), or determined by analyzing runtime data (550) can include but are not limited to: leakage rates of the source at given pressure accumulations, pressure limitations of the source, methane and other gases production rates under specific environmental conditions including temperatures, prediction of the production of various gases in combination with weather forecasts, effects on flow rates of barometric pressure, gas accumulation effects on pressure readings at the device, effects on source flow rate by downstream pressure drops, such as pressure drops at the destruction device, pumping rate correlation to air ingress into the source, and effects on the range of appropriate pressure and flow rates by environmental conditions such as water ingress into the source or water accumulation on the capture apparatus. These characteristics may be taken into account by the system, algorithmically or with the help of remote operators, to decide the pumping rate, number of nozzles or flares or other destruction devices to engage, and when to close the shut off valve to allow for pressure accumulation for batched operations, continuous operations or other operational modes. These control decisions (553) can be used to achieve various functions such maximization of gas destruction or conversion, stabilization of the source to give ideal input to the gas destruction or utilization device, utilization at a time when there is more value to the use or reduction of unwanted destruction byproducts.

[0322] Some source modelling behavior examples include: anticipating reduced gas production during times of detected low temperature by periodically shutting off the main valve to allow gas to accumulate into batches which can be more effectively destroyed; limiting inlet pressure range by varying the blower run speed to avoid levels at which the source is known to permit air ingress; or compensating for reduced source pressure during times of increased barometric pressure by opening more manifold valves.

Equipment alternatives and specifications

[0323] Piping: The selection of rigid or flexible piping will be dependent upon the end application. For convenience of assembly, the piping can be threaded on the inlet end to allow for simple connections with pipe fittings but alternatively it may be unthreaded and connected via compression fittings, flanges, flare fittings, grooved connections, clamp-gasket fittings, sanitary fittings, welded joints, solvent cement and/or adhesives.

[0324] Flow sensor: The flow sensor (104) may be either a mass-or volumetric flow meter such as a venturi or laminar differential pressure sensor, orifice plate flow meter, thermal mass flow sensor, ultrasonic flow sensor, or positive displacement sensor.

[0325] Valves: The valves may be as listed above or may also be other types of electrically, hydraulically or pneumatically actuated valves, such as (but not limited to) motorized ball, gate, globe, butterfly or needle valves; or solenoid valves.

[0326] Igniters: Although the igniters (106) are preferably high-voltage sparkers, or resistive heating elements (e.g. glow plugs), alternatives may be piezoelectric elements, mechanized flint strikers, unitized explosives (e.g. gunpowder caps), or pyrophoric materials. High-voltage, high-energy sparkers are more effective than low-energy sparkers at igniting biogas where a significant quantity of carbon dioxide may be present. Further advantages in the use of high-voltage sparkers, etc. are reliability, power efficiency, and low cost, making them the optimal choice for applicable locations. In addition, the use of high voltage sparkers in place of a pilot light potentially eliminates a consumable such as stored propane, that would otherwise need to be replaced in a maintenance cycle. The selection of alternate igniters (106) will be dependent on location, end use, and available power, and will be known to those skilled in the art.

[0327] Controllability is critical in order to handle the varied type of source gas. For example, an agricultural gas source that is derived from biological processes, such as liquid manure, will experience a large decrease in gas production rate during environmental temperature conditions below the freezing point of water, and also a large increase in gas production during environmental temperature conditions significantly above the freezing point of water. Existing solutions have a difficult time dealing with highly variable gas flows, and this is where the disclosed system provides a solution. The typical failure in this case is that a flare without modular control is not able to maintain ignition when flows decrease towards the seasonal minimum.

Example I

[0328] An abandoned underground coal or trona mine site may be capped with a relief well, which could be connected to the source inlet of the system. Because of the higher pressure of the source gas, this would typically be used with the embodiment of the invention in FIG. 1, with or without the blower (138).

Example II

[0329] An active underground coal mine site may have a drainage well drilled and vacuum pressure applied, with the outflow of a vacuum blower connected to the source inlet of the system. Because of the need for a vacuum blower, this would typically be used with the embodiment of the invention in FIG. 1, with the vacuum blower depicted in (138).

Example III

[0330] A natural seep in a body of water may be captured by a floating or submerged canopy and piped into the system's source inlet. Because of the low source pressure and the distributed nature of the source, this may be used with the embodiment of the invention depicted in FIG. 9. Alternatively, in this example, the gas may be piped either under its own hydraulic pressure or with the use of a blower into the embodiment of the invention depicted in FIG. 1.

Example IV

[0331] An agricultural manure pond may be covered and vented into the source inlet of the system. Because this type of source can be fed through a pipe from a pond cover, this would typically be used with the embodiment of the invention in FIG. 1. Additionally, considerations may be made in the material selection of the components for corrosive components such as hydrogen sulfide present in some agricultural gases. For example, the gas conditioner (253, 303) as depicted in FIG. 6 and FIG. 7 in such cases may include scrubber material to remove such gases for the protection of downstream components such as the gas composition sensors (252, 302).

Example V

[0332] A landfill or surface mine may have one or more drainage wells drilled and vacuum pressure applied, with the outflow of the vacuum blower connected to the source inlet of the system. Because of the use of a vacuum blower in this configuration, such a source would typically be used with the embodiment of the invention in FIG. 1, configured with the vacuum blower (138).