Containerized Gas Processing System with Evacuated Processing Compartment

Abstract

A system for processing gas streams has the form of, and is disposed in, an intermodal container. The container has a processing compartment with one or more cryogenic cells disposed in it, and is maintained in at least a partially evacuated condition, below atmospheric pressure. A second compartment has support equipment that is connected to the one or more cryogenic cells in the first compartment. Methods for managing such a system include maintaining the first compartment in the partially evacuated condition. In response to an increase in pressure within the first compartment, a controller may analyze the nature of the pressure increase. In case of fire or fire hazard, the controller may discharge inert gas from cores of the one or more cryogenic cells.

Claims

1. A gas processing system, comprising: an intermodal container having therein an airtight first compartment maintainable in an at least partially evacuated state at a predefined pressure, the airtight compartment having at least one cryogenic cell therein, the at least one cryogenic cell adapted to process gas.

2. The gas processing system of claim 1, further comprising: a second compartment within the intermodal container, the second compartment having one or more pieces of equipment connected to the at least one cryogenic cell in the first compartment.

3. The gas processing system of claim 2, wherein the airtight first compartment and the second compartment are divided from one another by first and second walls that are spaced from one another.

4. The gas processing system of claim 1, further comprising: a control system, including a controller, a vacuum pump controllable directly or indirectly by the controller, and a pressure sensor adapted to detect a pressure within the airtight first compartment; wherein the controller is adapted to take input from the pressure sensor and actuate the vacuum pump to maintain the airtight first compartment at the predetermined pressure.

5. The gas processing system of claim 4, wherein the control system further comprises a fire detector connected to the controller.

6. The gas processing system of claim 5, wherein the control system further comprises a gas analyzer.

7. The gas processing system of claim 1, further comprising an airtight exterior door opening into the airtight first compartment.

8. A method, comprising: maintaining at least one airtight compartment within an intermodal container at a predefined pressure less than an atmospheric pressure; and processing a gas stream in the at least one airtight compartment using one or more cryogenic cells adapted to cause a phase change in at least one component of the gas stream.

9. The method of claim 8, further comprising: receiving a signal indicating that a pressure within the at least one airtight compartment is above a defined pressure threshold greater than the predefined pressure; analyzing gas within the at least one airtight compartment; determining, based on said reading and said analyzing, whether a high-rate flammable gas leak is occurring; and establishing an alert when said determining indicates that the high-rate flammable gas leak is occurring.

10. The method of claim 9, wherein said determining further comprises establishing a leak rate.

11. The method of claim 9, further comprising discharging at least one core of the one or more cryogenic cells.

12. The method of claim 11, further comprising, before said discharging, closing one or more valves to discontinue flow of the gas stream into or within the one or more cryogenic cells.

13. The method of claim 9, further comprising returning the at least one airtight compartment to the defined pressure when said determining indicates that the high-rate flammable gas leak is not occurring.

14. The method of claim 8, further comprising: receiving a signal indicating that a fire exists within the at least one airtight compartment; and discharging at least one core of the one or more cryogenic cells.

15. The method of claim 14, further comprising closing one or more valves to discontinue flow of the gas stream into or within the one or more cryogenic cells prior to said discharging.

16. The method of claim 14, further comprising establishing a fire alert.

17. A system, comprising: an intermodal container; a processing compartment within the intermodal container, the processing compartment being airtight and having one or more cryogenic cells adapted to process a gas stream therein; and an equipment compartment within the intermodal container, the equipment compartment being separated from the processing compartment by at least one wall and having at least one piece of equipment therein, the at least one piece of equipment connecting to the one or more cryogenic cells in airtight fashion through the at least one wall; wherein the processing compartment is operationally maintained in at least a partially evacuated condition at a defined pressure.

18. The system of claim 17, wherein the at least one wall comprises at least two walls separated from one another by a distance.

19. The system of claim 18, further comprising: at least one vacuum pump disposed in the equipment compartment; at least one pressure sensor positioned and adapted to read a pressure within the processing compartment; and a controller connected to the at least one vacuum pump and the at least one pressure sensor; wherein the controller is adapted to control the at least one pressure sensor and the at least one vacuum pump to maintain the processing compartment in the at least partially evacuated condition at the predefined pressure.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0017] The invention will be described with respect to the following drawing figures, in which like numerals represent like features throughout the description, and in which:

[0018] FIG. 1 is a perspective view of a containerized gas processing and liquefaction system with an evacuated processing compartment according to one embodiment of the invention;

[0019] FIG. 2 is a perspective view of the container of FIG. 1 with a panel partially cut away to show the interior arrangement of the container;

[0020] FIG. 3 is a top plan view of the interior of the container of FIG. 1;

[0021] FIG. 4 is a schematic diagram of an active control system for the system of FIG. 1; and

[0022] FIG. 5 is a schematic flow diagram of a method for pressure control and fire suppression using the active control system of FIG. 4.

DETAILED DESCRIPTION

[0023] FIG. 1 is a perspective view of a modular, containerized system, generally indicated at 10, for processing, separating, and liquefying gas. Much of system 10 is contained within an intermodal shipping container 12, and in the view of FIG. 1, the container 12 is shown on a trailer 14, with the trailer 14 connected to a truck 16. FIG. 2 is a perspective view of the container 12 with one long wall panel 18 cut away to show its interior arrangement.

[0024] System 10 is used to separate components of raw gas streams, for example, natural gas from a well or from a renewable natural gas source, like a landfill. Separation, in this context, typically occurs by forcing one or more components of the gas stream to change phase under particular conditions of pressure and temperature. In some cases, system 10 may be used solely for liquefaction or solidification. Notably, system 10 uses cryogenic cells 20, some of which are visible in the view of FIG. 2, as a primary means of separation and liquefaction. Cryogenic cells 20 and their use in gas separation are described in, e.g., U.S. Pat. Nos. 11,306,957, 11,448,459, and 12,098,873, all of which are incorporated by reference herein in their entireties. As relevant here, a number of cryogenic cells 20, able to process millions of cubic feet of gas per day (e.g., 250 MCF/day), can fit in a single intermodal shipping container 12.

[0025] The container 12 is of typical overall construction, with corrugated steel wall panels 18, 22 mounted on a rectilinear steel frame, generally indicated at 24, that has intermodal connectors 26 at its corners. (As shown in the figures, the frame 24 is a rectangular prism in the illustrated embodiment.) The container 12 may be of standard dimensions, e.g., 8 feet (2.44 m) wide by 8 foot 6 inches (2.59 m) high. In some embodiments, the container could be a so-called high cube container, which adds a foot (0.3 m) in height. Depending on the embodiment, the container 12 may have any standard length. For reasons that will be explained below in more detail, in the illustrated embodiment, the panels 22 are welded to the frame 24 in such a way that the interior of the container 12 is airtight.

[0026] A typical intermodal shipping container is adapted to ship and to store goods. By contrast, the container 12 has the exterior attributes of an intermodal shipping container, including intermodal connectors 26, and can thus be placed on a truck chassis 14, on a trailer 16, or on a ship for transport. However, once on-site, the container 12 is not unloaded; rather, the container 12 itself is an integral part of the system 10. For example, the container 12 has external ports 30, 32, 34, 36 that allow it to receive a raw gas stream to be processed, to expel various components of that gas stream during processing, and to release a final product. The ports 30, 32, 34, 36 connect to the cryogenic cells 20 and other components within the container 12.

[0027] FIG. 3 is a top plan view of the container 12, with the top removed so as to show its internal arrangement. The container 12 has two compartments, a processing compartment 38 and an equipment/support compartment 40. The two compartments 38, 40 are separated by a pair of spaced-apart walls 42, 44. There may be, e.g., about 3 feet (one meter) of space between the walls that defines a small compartment 46. Although various tube and cable bundles 48, 50 from the equipment/support compartment 40 may pass through the compartment 46, the compartment 46 itself has nothing in it; rather, it serves as a dead space and a firewall between the processing compartment 38 and the equipment/support compartment 40.

[0028] Because system 10 may process flammable gases, such as methane and hydrogen, as well as mixed-gas streams that contain volatile organic compounds with different flash points, fire protection is of some importance. The walls 42, 44 and the compartment 46 between them provide one type of fire protection, isolating the equipment/support compartment 40 from the processing compartment 38. In some embodiments, all components with moving partsanything that could create a sparkis in the equipment/support compartment 40.

[0029] However, system 10 goes one step further: in system 10, the processing compartment 38 is at least partially evacuated. As used here, the term partially evacuated means that the processing compartment 38 is maintained at lower-than-atmospheric pressure. The pressure in the processing compartment 38 may be any pressure less than atmospheric pressure, depending on the particular situation (e.g., the flammability of the gases involved, the risk of fire, etc.). For example, the pressure in the processing compartment 38 may be one-half of atmospheric, one-third of atmospheric, one-quarter of atmospheric, etc. In a particular embodiment, the processing compartment 38 may be maintained at a pressure of 10 Torr or less. At a relatively low pressure, there may not be sufficient oxygen to ignite or to sustain a fire, even if flammable gas leaks within the processing compartment 38.

[0030] As was noted above, the walls 18, 22 are welded on the frame 24 so that the container 12 is airtight. (Whereas a traditional intermodal container has plank flooring supported by steel beams, the container 12 has a panel welded to the frame 24 on the bottom as well.) If it is impractical to make the entire container 12 airtight, then an airtight compartment can be constructed within the container 12 as the processing compartment 38. That is, in some embodiments, it may be the compartment 38 or compartments 38, 40 within the container 12 that are themselves airtight, rather than the whole of the container 12.

[0031] In the illustrated embodiment, other measures are taken to maintain the airtightness of the processing compartment 38. For example, as can be seen in FIGS. 1 and 2, the processing compartment 38 is accessible through an airtight hatch or door 50 in the rear wall panel 22 of the container 12. Any other access points into or out of at least the processing compartment 38 would also be airtight, e.g., scalable hatches. As is shown in FIGS. 1 and 2, the equipment/support compartment 40 is also accessed through an airtight door 52. While an airtight door 52 on the equipment/support compartment 40 is optional, it may be helpful in some cases. For example, in case of a breach between the two compartments 38, 40, the interior of the container 12 as a whole will still be at less-than-atmospheric pressure.

[0032] FIG. 3 shows pass-throughs 54, 56, 58, 60 in the walls 42, 44 between the processing compartment 38 and the equipment/support compartment 40. At least the pass-throughs 58, 60 in the wall 42 immediately adjacent to the processing compartment 38 are airtight, e.g., made with sealing structure, O-rings, gaskets, etc. In many cases, all of the pass-throughs 54, 56, 58, 60 may be airtight. If it is undesirable for cables and hoses to transit through the walls 42, 44, the pass-throughs 54, 56, 58, 60 could be sealed, double-sided connectors, connecting to separate hoses and cables on each side, such that cables and hoses 62, 64 from the equipment/support compartment 40 do not directly transit through the walls 42, 44. Ultimately, many ways of sealing such connections are known, and any may be used, depending, at least in part, on the desired less-than-atmospheric pressure within the processing compartment. As those of skill in the art will appreciate, the lower the desired pressure within the processing compartment 38, the more stringent the airtightness measures will likely be.

[0033] The airtightness measures described above are essentially passive measures. In some embodiments, this may be enough: the container 12 may be sealed, the processing compartment 38 may be pumped down by an externally-applied pump, and processing may occur. However, in other embodiments, system 10 may include an active control system that monitors conditions within the processing compartment 38, maintains the internal pressure at desirable levels, and determines whether a leak or a fire is occurring.

[0034] FIG. 4 is a schematic diagram of such a control system, generally indicated at 100, shown disposed within the container 12. The control system 100 uses the attributes of the cryogenic cells 20 in the processing compartment 38.

[0035] Several cryogenic cells 20 are disposed in the processing compartment 38. A functional system may include, e.g., 6-12 cryogenic cells 20, although four cryogenic cells 20 are shown in FIG. 4 for simplicity. Each cryogenic cell 20 has a core 102 filled with a liquid cryogen 104. Adjacent to the core 102 is a sealed, pressurizable space 106. Within the pressurizable space 106, a set of coils 108 is provided. The pressurizable space 106 places the coils 108 in selective thermal communication with the core 102, depending on the pressure, and thus, the mass, within the pressurizable space 106.

[0036] The container 12 has, or is associated with, a main feedstock inlet 105 (typically one of the ports 30, 32, 34, 36 described above) that has a main feedstock valve 107. Each cryogenic cell has ports 110, 112 to input gas into the coils 108 and to discharge gas from the coils 108. At least one of the ports 110, 112 of one of the cryogenic cells 20 is connected to the inlet 105 through the main feedstock valve 107. The remainder of the ports 110, 112 are connected to plumbing to route various gas streams for further processing, although for the sake of simplicity, the plumbing is not shown in FIG. 4. As heat exchange with the pressurizable space occurs, the liquid cryogen 104 within the core 102 vaporizes. Vaporized cryogen is drawn off by a first core port 114 to regenerating equipment 116 in the equipment/support compartment 40. This regenerating equipment 116 may be a compressor, a cryocooler, or a combination of components that return the vaporized cryogen to liquid phase. Liquid cryogen is returned to the core 102 through a second port 118. The first port 114 is associated with a relief valve 120, one function of which will be described below in more detail. Many variations on this basic construction are possible. Additional details of structure and function of the cryogenic cells 20 can be found in the references cited above.

[0037] A vacuum pump 122 is present in the equipment/support compartment 40 and is connected to an inlet 126 in the processing compartment 38 by a valve 124. A second valve 128 places the outlet line 130 of the vacuum pump 122 in communication with the exterior of the container 12. In some cases, more than one vacuum pump 122 may be used, each set up substantially the same as shown. A pressure sensor 132 and a detector/analyzer 134, such as a mass spectrometer, are present in, or coupled to, the inlet 126. A fire detector 136, which may be a radioisotope-based smoke detector, a thermal detector or imager, or the like, is present in the processing compartment 38. A controller 138 is connected or coupled to the vacuum pump 122, the valves 124, 128, and the detectors 124, 128, 132, 134. The processing compartment 38 may also have one or more repressurization valves 140 which open to the outside and are also under the control of the controller 138.

[0038] The controller 138 would typically be programmed with several basic directives, e.g.: (1) maintain the pressure within the processing compartment 38 at the predetermined, desired low pressure; (2) detect leaks of gas; and (3) facilitate entry into the processing compartment if needed for maintenance, fire suppression, or other purposes. These directives may be prioritized and implemented in different ways. FIG. 5 is a schematic flow diagram of a method, generally indicated at 200, for controlling a system like system 100 to accomplish the kinds of directives set forth above.

[0039] Method 200 begins at 202 and continues with task 204. In task 204, the controller 138 checks for a fire. This may be done by checking the fire detector 136 directly, or it may be done by assessing other data, such as performance data for system 10, with which the controller 138 is supplied. For example, a temperature within the processing compartment 38 that is one or two standard deviations above normal operating temperatures may indicate a fire, as may a rapid increase in the temperature of or around a particular cryogenic cell 20. Other things detected by the analyzer 134, such as high particulate matter or the presence of certain combustion byproducts in high concentrations, could also indicate fire.

[0040] Method 200 continues with task 206. If a fire is detected, either by the fire detector 136 or indirectly by other instruments 132, 134 (task 206: YES), control of method 200 passes to task 208 to address the fire. Otherwise (task 206: NO), method 200 continues with task 214.

[0041] In task 208, the controller 138 begins by establishing an alert, which may be communicated by display on a terminal, by other auditory or visual alerts (e.g., sirens, flashing lights, etc.), by SMS text message, by e-mail, or by any and all other means necessary. Method 200 continues with task 210.

[0042] In task 210, the controller 138 orders the feedstock valve 107 for system 10 to be closed. If system 10 has multiple feedstock valves 107, all of the valves may be closed. In task 210, the controller 138 may shut these valves either by directing that such be done itself or by sending a request to a master system controller. In task 210, other valves may be shut as well. For example, the ports 114, 116 leading to each cryogenic cell 20 may be valved, and those valves may be closed as well, as may any valves leading to other inlet/outlet ports 30, 32, 34, 36. One purpose of task 210 is to isolate system 10 and its cryogenic cells 20 so as to provide an active fire with as little fuel as possible. Another purpose of task 210 is to prevent downstream contamination of the product(s) of system 10, e.g., to prevent a stream of liquefied hydrogen, helium, methane, nitrogen, oxygen, etc., from being contaminated with combustion products or other contaminants. Method 210 continues with task 212.

[0043] After task 210, system 10 and its individual cryogenic cells 20 are isolated, hopefully limiting the amount of available fuel for a fire. In some cases, the controller 138 may pause momentarily after task 210 and check sensors 132, 134, 136 to see if there is any evidence that the fire has been extinguished solely by the fuel cut-off before proceeding to task 212.

[0044] In task 212, the controller 138 tries to extinguish the fire. In this, the features of the cryogenic cells 20 are helpful. The core 102 of each cryogenic cell 20 contains a liquid cryogen: liquid nitrogen, liquid carbon dioxide, liquid argon, or liquid helium as examples. All of these liquid cryogens are non-flammable in gas form. Moreover, at least one port 114 to the core 102 has a valve 120 attached to it, e.g., by a T-connector. The valve 120 may be, e.g., a pneumatic valve that is under the control of the controller 138. (For example, system 100 may include a small tank of actuating gas, such as nitrogen, in the equipment/support compartment 40, and that tank may have an electrically-actuatable valve, such as a solenoid valve, that the controller 138 can directly or indirectly control.)

[0045] Most of the cores 102 will be maintained at elevated pressure, e.g., up to 300 psi (2 MPa). Thus, when the valves 120 are actuated, gas will be expelled at high pressure into the processing compartment 38, rapidly filling the processing compartment 38 with inert gas and, hopefully, extinguishing any fire. This is shown in task 212 of method 200. In discharging the cores 102 using the valves 120, the controller 138 may be aware of, and may consider the nature of, the cryogen in each of the cores 102. In some cases, the controller 138 may prioritize discharging the cores 102 that contain readily available, relatively inexpensive cryogens, like nitrogen and carbon dioxide, before discharging the cores 102 containing rarer cryogens, like argon and helium. In discharging the cores 102 in task 212, the controller 138 may, in some cases, monitor the pressure within the processing compartment 38 and discharge the cores 102 only to the extent necessary to pressurize the compartment 38 to atmospheric pressure. In other cases, the controller 138 may discharge the cores 102 until there is some indication that the fire has been extinguished, irrespective of the pressure within the container 12.

[0046] Discharging the cores 102 by actuating the valves 120 in task 212 has another effect. The hatch 50 on the processing compartment 38 is an external hatch that opens outward. When the processing compartment 38 is evacuated, the hatch 50 is drawn tighter against its seals and becomes virtually impossible for a human to open. In a routine situation, the controller 138 can either reverse the vacuum pump 122 or open the main pressure equalization valve 140 to repressurize the processing compartment 38. However, if there is a fire, both options are disadvantageous, as both could allow more oxygen in to feed the fire. Additionally, firefighters may need quick access to the processing compartment 38 to fight the fire or to address its aftermath, and conventional repressurization by reversal of the vacuum pump 122 or opening of the repressurization valve 140 is relatively slow. On the other hand, opening valves 120 to large, high-pressure inert gas sources (i.e., the cores 102) is a relatively fast way to repressurize the processing compartment 38 to allow access. Personnel who enter immediately after rapid repressurization/fire extinguishing operations in task 212 will likely need to wear self-contained breathing apparatus, but that kind of equipment is readily available to, and commonly used by, firefighters.

[0047] After task 212, the controller 138 may establish a signal or provide an alert that the processing compartment 38 has been repressurized before method 200 returns at task 290.

[0048] In the particular embodiment illustrated by method 200, the controller 138 essentially checks for and addresses the worst contingency-fire-first. As was noted above, if there is no fire (task 206: NO), method 200 proceeds with task 214 and checks the pressure within the processing compartment 38, before continuing with task 216, a decision task. If the pressure is at the predetermined, desired pressure (in some cases, plus or minus a threshold or measurement error) (task 216: YES), method 200 returns to task 206 and continues in a monitoring loop until conditions change. If the pressure is not at the predetermined, desired pressure (task 216: NO), method 200 continues with task 218, and the controller 138 activates and reads the gas detector/analyzer 134.

[0049] Task 218 recognizes that not all leaks are created equal. That is, a minor leak of outside atmospheric gas into the processing compartment 38 may be relatively benign, while a leak of flammable processing gas within the processing compartment 38 may be less benign, as it may indicate serious equipment failure or result in a fire or explosion.

[0050] Method 200 continues with task 230 and the controller 138 analyzes the nature of the leak. By this point in method 200, the controller 138 knows the pressure within the processing compartment 38 and the nature of the gas or gases creating that pressure. The controller 138 may also know the rate at which the pressure is increasing if multiple readings are taken over a period of time in task 218, or if the pressure is logged in each iteration of method 200. Given those data points, in task 230, the controller 138 determines whether there is a high-rate leak of flammable gas. The threshold for a high-rate leak will vary with the circumstances, including the size of the processing compartment 38, the nature of the flammable gas being processed, and the preferences of the operator of system 10. In general, a high-rate flammable leak is one that is likely to result in a fire or explosion, or, at least, one that indicates a degree of equipment malfunction or failure that requires significant or immediate maintenance. If the controller 138 concludes that such a high-rate flammable leak is occurring (task 220: YES), control of method 200 passes to task 208. That is, in this embodiment, the controller 138 treats a high-rate flammable leak as akin to a fire and takes immediate action to isolate system 10 and to rapidly recompress the processing compartment 38 in order to allow access.

[0051] As those of skill in the art will realize, other responses are possible to a high-rate flammable leak. For example, in some cases, the controller 138 may try to sequentially shut available valves in order to isolate the section of equipment in which the leak is occurring. If the section of equipment with the leak can be isolated and shut off and there is no active fire, the controller 138 may repressurize the processing compartment via the regular repressurization valve 140 instead of opening the cores 102 and discharging their contents with the valves 120. The philosophy behind this is simple: if the cores 102 are discharged, returning system 10 to operation will require a supply of fresh liquid cryogen and significant effort to refill the cores 102. If there is an active fire, core discharge is justified to protect life and property; if there is no fire and some other action is possible, the controller 138 may execute that action first, before core discharge.

[0052] If there is not a high-rate flammable leak (task 220: NO), method 200 continues with task 222. In establishing that there is not a high-rate flammable leak, the controller 138 also implicitly establishes that whatever the gas mixture in the processing compartment 38 is, it is safe to pump out. That is, the mixture is such that travel through a vacuum pump, and the potential for moving parts that could create sparks, is safe. Thus, in task 222, the vacuum pump 122 is activated and begins to pump the processing compartment 38 down to the desired pressure once more.

[0053] In the diagram of FIG. 4, the valve 128 between the vacuum pump 122 and the outside is shown as simply exhausting gases to the outside. However, in some embodiments, the valve 128 could be connected to a thermal oxidizer or other form of gas disposal, so that gases removed from the processing compartment 38 are exhausted and treated in a way that reduces or eliminates pollution.

[0054] Method 200 continues with task 224. In the illustrated embodiment, the controller 138 keeps logs of the pressure in the processing compartment 38 and other relevant measurements and parameters. Minor leaks are to be expected in a system like system 10, but in task 224, the controller 138 logs the leak (and, often, the analysis of the gases present in the processing compartment 38 and the action taken to resolve the leak). In task 226, if the log files indicate a persistent leak that is not necessarily a threat to life or property but will require maintenance (task 226: YES), method 200 continues with task 228 and appropriate alert(s) are sent before method 200 returns at task 290. If analysis in task 226 does not indicate a persistent leak (task 226: NO), control of method 200 returns to task 204 and monitoring continues until conditions change.

[0055] For simplicity in description, each decision task in method 200 (i.e., tasks 206, 216, 220, and 226) is presented above as a decision for the controller 138 alone. That may not be the case in all embodiments. Rather, there may be some decisions that are made by the controller 138 alone (e.g., fire, task 206), while other decision tasks may be presented to a human operator. For example, in some cases, the controller 138 may present a human operator with the available data to determine whether a high-rate flammable leak or a persistent leak is occurring. In yet other cases, the controller 138 may make decisions that are subject to override by a human operator within some period of time. For example, the controller 138 may present an alert such as Fire detected. Valves will be closed and cores discharged in 30 seconds without override.

[0056] Additionally, much of the description above presents the controller 138 as the sole deciding component within system 100. However, that need not always be the case. As was noted above, in some cases, the controller 138 may report to a master system controller that makes some or all of the necessary decisions. There may also be a network of sub-controllers, each of which is responsible for a particular set of components and actions, e.g., opening or closing certain valves.

[0057] Any embodiment of a pressure and fire control method, such as method 200, may also consider the particular structure and arrangement of system 10 in making decisions. For example, as U.S. Pat. No. 11,448,459 explains, a gas processing and liquefaction system of this sort is often divided into stages, with each stage responsible for liquefaction of a particular component of the raw gas stream or, at least, a group of components with similar liquefaction temperatures and pressures. Gas in a stage is recycled through that stage until sufficient liquefaction has been achieved before the stream is released to a separator, followed by the next stage. Particularly in addressing a fire, those stages and their contents may be taken into account. For example, stages that contain the highest concentration of flammable gases may be isolated first in task 210. If there are stages that separate non-flammable gases, like carbon dioxide and nitrogen, from the rest of the stream, instead of isolating those stages, any separated, non-flammable gases may be vented into the processing compartment 38 in task 212, either instead of or along with the contents of the cores 102. In that case, in addition to valves used to release the contents of one stage into another, at least selected stages would include purge/discharge valves.

[0058] While pressure control and fire suppression methods may be as complex or more complex than that described with respect to method 200 of FIG. 5, such methods may also be less complex. For example, system 100 includes a gas detector/analyzer 134. Some embodiments may omit that device. In that case, a controller may judge the situation entirely according to the measured pressure in the processing compartment 38 and, in at least some cases, the rate of pressure increase: if the pressure is too high or is increasing too rapidly (with too high and too rapidly defined for the particular system and application), the controller in that system may declare an exception or emergency irrespective of the nature of the gases, shut the valves, and rapidly repressurize by core discharge or repressurization valve, or alternatively, take whatever other actions are justified by the circumstances.

[0059] In other words, in method 200, the controller 138 is smart enough to distinguish between minor, benign leaks and large, potentially disastrous leaks. A controller need not be capable of that level of discernment in order to maintain the predetermined, desired pressure in the processing compartment 38 and to respond to leaks and fire.

[0060] Much of this description has assumed that there are two compartments 38, 40 in the container 12, one of which is at least partially evacuated and one of which is not. In different embodiments, this may be different. For example, in the simplest embodiment, the container may have only one compartment in which both the cryogenic cells 20 and the support equipment may be placed. That compartment would be at least partially evacuated. In other embodiments, there may be multiple processing compartments, some of them at least partially evacuated and some of them not. For example, if the system is divided into stages, the stages in which the stream contains flammable gases may be placed in evacuated compartments, while the stages that process only non-flammable gases may be in compartments that are held at atmospheric pressure.

[0061] There are several advantages to having at least one equipment/support compartment 40 maintained at normal atmosphere. First, operating at low pressure or vacuum can be hard on some equipment, and may require specialized equipment. Second, keeping the equipment/support compartment 40 at normal atmosphere allows the equipment within that compartment to be maintained more easily, potentially without interrupting the use of system 10.

[0062] This description uses the term about. When that term is used to modify a number or numerical range, it means that the number or numerical range may vary so long as the described result does not change. If it cannot be discerned what range would not cause the described result to change, the term about should be interpreted to mean10%.

[0063] While the invention has been described with respect to certain embodiments, the description is intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the appended claims.