DEVICE FOR REFORMING A VOC GAS

Abstract

A device and method for producing a reformate fuel from a hydrocarbon gas source. The invention enables the conversion of a dilute hydrocarbon gas into a more easily consumable reformate fuel. Gases having low concentrations of hydrocarbons are concentrated using a concentrator into a gaseous or liquid concentrated VOC fuel. The concentrated VOC fuel is then converted into a reformate using a reformer. The reformate is more easily consumed by an energy conversion device such as a combustion engine, fuel cell, sterling engine or similar device that converts chemical energy into kinetic or electrical energy. The reformer enables complex hydrocarbon fuels that are not normally suitable for use in an energy conversion device to be converted into a reformate. The reformate may be directly supplied into the energy conversion device.

Claims

1. An energy producing device receiving a dilute VOC gas stream comprising: a concentrator that concentrates the VOC into concentrated VOC fuel; a sweep gas injector injecting sweep gas into the concentrator to remove the concentrated VOC fuel; a reformer converting said sweep gas and concentrated VOC fuel into reformate; and an energy conversion device consuming said reformate to produce energy.

2. The device of claim 1, wherein said concentrator includes an adsorbent media adsorbing said dilute VOC gas stream.

3. The device of claim 2, wherein said concentrator comprises an adsorbing chamber where said dilute VOC gas stream is adsorbed on said adsorbent media and a desorbing chamber where said adsorbed VOC gas stream is desorbed.

4. The device of claim 2, wherein said adsorbent media is selected from the group comprising activated carbon, zeolite, synthetic resin and mixtures thereof.

5. The device of claim 1, wherein said concentrator concentrates said concentrated VOC fuel to a concentration greater than 15,000 ppm.

6. The device of claim 5, wherein said concentrator concentrates said concentrated VOC fuel to a concentration greater than 200,000 ppm.

7. The device of claim 1, wherein said sweep gas is steam.

8. The device of claim 1, wherein said sweep gas is a gaseous fuel.

9. The device of claim 1, wherein said sweep gas is inert.

10. The device of claim 9, wherein said sweep gas is nitrogen.

11. The device of claim 2, wherein said adsorbent media is in a fluidized bed.

12. The device of claim 2, wherein said adsorbent media is affixed to a rotating wheel.

13. The device of claim 2, wherein said adsorbent media is contained in fixed beds.

14. The device of claim 1, further comprising a cooler cooling said reformate.

15. The device of claim 1, wherein said reformate contains H.sub.2 gas and oxides of carbon.

16. The device of claim 1, wherein the device contains filters that filter particulates from the dilute VOC gas stream.

17. The device of claim 1, wherein said dilute VOC gas stream comprises straight chain hydrocarbons, branched hydrocarbons, aromatic hydrocarbons, oxygenated hydrocarbons and mixtures thereof.

18. The device of claim 1, wherein said dilute VOC gas stream is between 1 ppm and 5000 ppm VOC.

19. The device of claim 1, wherein said dilute VOC gas stream is paint exhaust.

20. The device of claim 1, wherein said dilute VOC gas stream is gasoline vapor.

21-31. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 illustrates a device for removing dilute VOC from a gas stream and concentrating them into a high temperature gaseous fuel consisting of H.sub.2, CO, and various inert gases such as CO.sub.2, nitrogen, and water.

[0015] FIG. 2 illustrates an alternative device for removing dilute VOC from a gas stream and concentrating them into a high temperature gaseous fuel consisting of H.sub.2, CO, and various inert gases such as CO.sub.2, nitrogen, and water.

[0016] FIG. 3 illustrates a device for removing dilute VOC from a gas stream and concentrating them into a low temperature gaseous fuel consisting of H.sub.2, CO, and various inert gases such as CO.sub.2, nitrogen, and water.

DETAILED DESCRIPTION

[0017] The present invention is illustrated in a series of drawings where like elements have the same suffix, but the initial number matches the figure reference. A table of the various elements and reference numbers is reproduced below to aid in understanding the invention:

TABLE-US-00001 ELEMENT FIG. 1 FIG. 2 FIG. 3 DEVICE 100 200 300 SOURCE 101 201 301 DAMPER 102 202 302 DAMPER 103 203 303 FILTERS 110 210 310 FAN 115 215 315 CONCENTRATOR 120 220 320 LINE 121 221 321 VENT 122 222 322 OUTLET 123 223 323 FAN 125 LINE 129 CONDENSER 130 LINE 131 REFORMER 140 240 340 LINE 141 241 341 INLET 142 242 342 LINE 143 243 343 INLET 144 244 344 LINE 145 245 345 FUEL COOLER 350 LINE 351 ECD 160 260 360 INLET 161 261 361 OUTLET 162 262 362 OUTPUT 163 263 363 SWITCHGEAR 170 270 370 CONNECTOR 171 271 371

[0018] In each embodiment of the invention, VOC is reduced into hydrogen and oxides of carbon. The procedure provides a process that ultimately utilizes the hydrocarbons contained in the VOC to extract energy. The device reduces air emissions while using the multi-component solvents separated from the dilute VOC gas stream as fuel to produce electricity or kinetic energy.

[0019] In one embodiment, a dilute VOC gas stream from a manufacturing process is filtered through a multiple stage filtration system if particulate material is entrained within the gas stream. Then, the gas is directed into an adsorption chamber where the VOC is removed from the waste stream onto an adsorbent media. The adsorbent media is isolated from the VOC laden gas source and heated to release, or desorb, the VOC at regular intervals. The timing of the desorb cycle is such that the level of VOC saturation on the adsorbent media does not exceed a predetermined level. Heating the VOC laden adsorbent media causes the VOC to flash to high temperature vapor, which is then directed to a reformer, and then to an ECD that can be either an engine or fuel cell. Engines may be used to power equipment or to operate generators to produce electricity. In an alternative embodiment, a sweep gas passes over the adsorbent media to desorb the adhered VOC. The sweep gas may be steam, inert gas, combustion products, or another fuel such as methane or another alkane. The concentrated sweep gas-VOC mixture then passes into a reformer. In another embodiment, the reformate is cooled before introduction into the ECD. The water and CO.sub.2 gases resulting from oxidation in the ECD are exhausted to the atmosphere. A control system is used to monitor and control the sequence.

[0020] FIG. 1 illustrates a first embodiment of a device 100 to remove VOC from the effluent gas stream of a manufacturing process and convert the VOC into a fuel that can be used to generate electricity. The VOC treatment begins at the VOC laden gas source 101, which allows VOC laden gas to pass through normally open damper 102 to the inlet of optional multiple stage particulate filters 110. The damper 102 directs the dilute VOC gas stream to be processed by the device 100. Normally closed bypass damper 103 allows temporary exhaustion to the atmosphere when the exhaust gas treatment device 100 is not operating. A booster fan 115 directs the filtered gas stream to the inlet of the adsorption/desorption concentrator 120. The dilute VOC gas stream enters an adsorption portion of the concentrator 120 where the VOC adheres to the adsorbent media as the gas passes through the concentrator 120. Exhaust vent 122 allows the process gas, now cleaned of VOC, to vent to the atmosphere or be redirected for use within the process or into another manufacturing process. The adsorbent media can be any commercially available adsorbent, such as activated carbon, zeolite, synthetic resin or mixtures thereof. The VOC laden adsorbent media, in a continuous loop, are directed to the desorption portion of the concentrator 120 where the entrained VOC is desorbed by heating the adsorbent media and passing an inert sweep gas, such as nitrogen, through the concentrator 120. The VOC is entrained in the sweep gas and proceeds out of the concentrator 120 via outlet 123 to a condenser 130. The condenser 130 cools the inert gas to a temperature, which is below the flash temperature of the VOC but above the condensation temperature of the inert gas, thereby separating the VOC (liquid) from the inert gas (gaseous) in the condenser 130. The inert gas is recycled through line 129 to fan 125 and through inlet line 121 into the desorption portion of the condenser 130. Nitrogen or another inert gas, with a condensing temperature significantly below the condensing temperature of the VOC, will be used to ensure adequate separation. The VOC, now in liquid form, exits the condenser through outlet line 131, and flow to reformer 140.

[0021] The reformer 140 breaks down the VOC into H.sub.2, CO, CO.sub.2, and water through a partial oxidation process such as Auto Thermal Reforming (ATR). Process water for the fuel processor enters through water inlet 142. Air is added through inlet line 141. Supplemental fuel, such as natural gas, is available through inlet line 144. Controls for the reformer 140 regulate the airflow in such a way as to maximize the production of H.sub.2 and CO, and minimize the production of completely oxidized byproducts while maintaining thermal equilibrium. Water is condensed from the fuel stream after partial oxidation, and exits the fuel processor through drain line 143. The processed fuel, H.sub.2 and CO, exits the fuel processor through line 145 to the inlet of the ECD 160, in this case, either a fuel cell or an engine. Additional air for oxidation within the ECD 160 is provided through inlet 161, which may be the redirected clean air from the vent 122. Air, CO.sub.2, and water vapor exit the ECD 160 through outlet 162. The power output 163 connects to electrical switchgear 170. If the electrical power is produced by a fuel cell, the DC power is converted to AC power and stepped up to make it compatible with the facility's internal power grid. If the ECD 160 is a Stirling cycle engine, the AC power produced is stepped up via the switchgear. The connection to the facility's power grid, a protected bus that enables the device 100 to be self-supporting for emergency shutdown, is through connector 171.

[0022] While the device 100 is capable of operating on supplemental fuel, the amount of supplemental fuel added through valve 164 will be substantially below 90% and preferably near 0%. The device 100 is designed to operate completely on the energy content of the VOC fuel. Supplemental fuel is generally used in the initial device 100 start-up or when the output of the dilute VOC gas source falls below the efficient operation of device 100. Enabling the operation of device 100 exclusively on supplemental fuel provides redundant back-up power for the facility employing the device and is helpful in justifying the installation cost of the device.

[0023] The device may be scaled to accommodate large or small gas streams. In one application an automotive paint booth was ducted to device 100. The booth provided between 2000 and 6500 scfm of diluted VOC gas in air when it was fully operational. This dilute VOC gas stream was between 10 and 1000 ppm of aromatics such as xylene, straight chains such as heptane, and oxygenated hydrocarbons such as butyl acetate. At this concentration, the dilute VOC is below the Lower Explosion Limit of VOC in air.

[0024] Concentrator 120 increases the concentration of VOC to greater than 15,000 PPM and preferably to more then 200,000 PPM. Because the concentrated VOC is entrained in inert gas and not air, the risk of explosion is no greater than that of a pressurized fuel line. Other applications for the present invention include the capture of formaldehyde and acidic acid released during the manufacture of ethanol or the VOC emitted in baking. VOC that are entrained in soil or water can be evolved into a dilute VOC gas stream that is then supplied to device 100 for processing. In another application, the device could be used to capture gasoline vapors vented from underground or above ground tanks, tanker trucks or ships or other vessels during filling or servicing. Many other applications that involve dilute VOC will be readily apparent to those skilled in the art and are contemplated by this invention.

[0025] FIG. 2 illustrates another embodiment of a device 200 to remove VOC from the effluent gas stream of a manufacturing process and convert the VOC into a fuel that can be used to generate electricity. The VOC treatment begins at the VOC laden gas source 201, which allows the VOC laden gas stream to pass through normally open damper 202 to the inlet of an optional multiple stage particulate filters 210. Normally closed bypass damper 203 allows temporary exhaustion to the atmosphere when the exhaust gas treatment device is not operating. A booster fan 215 directs the filtered gas stream to the inlet of the concentrator 220. The gas stream first enters an adsorption portion of concentrator 220 where the VOC adheres to the adsorbent media as the gas passes through the concentrator 220. The adsorbent media can be any commercially available adsorbent, such as activated carbon, zeolite, synthetic resin or mixtures thereof. The VOC laden adsorbent media, in a continuous loop, are directed to a desorption portion of concentrator 220 where 200-600 F. steam from an external steam generator or boiler device enters the concentrator 220 through inlet line 221 to heat the adsorbent media and vaporize the VOC to remove them (desorb) from the adsorbent media. Alternatively, a sweep gas composed of inert combustion products or a gaseous fuel such as methane or another alkane may be used as a carrier of the desorbed VOC. An additional heat source (not shown) may be required for the desorption portion of the concentrator 220. Exhaust vent 222 allows the process gas, now cleaned of VOC, to vent to the atmosphere or be redirected for use within the process or into another manufacturing process. The VOC, now in a gaseous form and entrained in a sweep gas, exit the concentrator 220 as a concentrated fuel via outlet 223 that directs it to a reformer 240.

[0026] The reformer 240 breaks down the VOC into H.sub.2, CO, CO.sub.2, and water through a partial oxidation process such as Auto Thermal Reforming (ATR). If necessary, additional process water for the fuel processor enters through water inlet 242. Air is added through inlet line 241. Supplemental fuel, such as natural gas, is available through inlet line 244. Controls for the reformer 240 regulate the airflow in such a way as to maximize the production of H.sub.2 and CO, and minimize the production of completely oxidized byproducts while maintaining thermal equilibrium. Water is condensed from the fuel stream after partial oxidation, and exits the fuel processor through drain line 243. The processed fuel, H.sub.2 and CO, exits the fuel processor through line 245 to the inlet of the ECD 260, in this case, either a fuel cell or an engine. Additional air for oxidation within the ECD is provided through inlet 261, which may be the redirected clean air from the vent 222. Excess air, CO.sub.2, and water vapor exit the ECD through outlet 262. The power output 263 connects to electrical switchgear 270. If the electrical power is produced by a fuel cell, the DC power is converted to AC power and stepped up to make it compatible with the facility's internal power grid. If the ECD 260 is a Stirling cycle engine, the AC power produced is stepped up via the switchgear. The connection to the facility's power grid, a protected bus that enables the device 200 to be self-supporting for emergency shutdown, is through connector 271.

[0027] FIG. 3 illustrates another embodiment of a device 300 to remove VOC from the effluent gas stream of a manufacturing process and convert the VOC into a fuel that can be used to generate electricity. The VOC treatment begins at the VOC laden gas source 301, which allows the VOC laden gas stream to pass through normally open damper 302 to the inlet of an optional multiple stage particulate filters 310. Normally closed bypass damper 303 allows temporary exhaustion to the atmosphere when the exhaust gas treatment device is not operating. A booster fan 315 directs the filtered gas stream to the inlet of the adsorption/desorption concentrator 320. The gas stream first enters an adsorption portion of the concentrator 320 where the VOC adheres to the adsorbent media as the gas passes through the concentrator 320. The adsorbent media can be any commercially available adsorbent, such as activated carbon, zeolite, or synthetic resin. The VOC laden adsorbent media, in a continuous loop, are directed to the desorption portion of the concentrator 320 where 200-600 F. steam from an external steam generator or boiler system enters the concentrator 320 through inlet line 321 to heat the adsorbent media and vaporize the VOC to remove them (desorb) from the adsorbent media. Alternatively, a sweep gas composed of inert combustion products or a gaseous fuel such as methane or another alkane may be used as a carrier of the desorbed VOC. If natural gas is used, sulfur scrubbers may be needed to remove sulfur and other materials that may contaminate the adsorbent media. An additional heat source (not shown) may be required for the desorption portion of the concentrator 320. Exhaust vent 322 allows the process gas, now cleaned of VOC, to vent to the atmosphere or be redirected for use within the process or into another manufacturing process. The VOC, now in a gaseous form and entrained in the sweep gas, exit the adsorption/desorption concentrator 320 via outlet 323 and are directed to a reformer 340.

[0028] The reformer 340 breaks down the VOC into H.sub.2, CO, CO.sub.2, and water through a partial oxidation process such as Auto Thermal Reforming (ATR). If necessary, additional process water for the fuel processor enters through water inlet 342. Air is added through inlet line 341. Supplemental fuel, such as natural gas, is available through inlet line 344. Controls for the reformer 340 regulate the airflow in such a way as to maximize the production of H.sub.2 and CO, and minimize the production of completely oxidized byproducts while maintaining thermal equilibrium. Water is condensed from the fuel stream after partial oxidation, and exits the fuel processor through drain line 343. The processed fuel, H.sub.2 and CO, exits the fuel processor through line 345 to the inlet of a fuel cooler 350, where it is cooled to a useable temperature. The fuel exits the cooler via valve 351 and is directed to the inlet of the ECD 360, in this case, either a fuel cell or an engine. Additional air for oxidation within the ECD is provided through inlet 361, which may be the redirected clean air from the vent 322. Excess air, CO.sub.2, and water vapor exit the ECD through outlet 362. The power output 363 connects to electrical switchgear 370. If the electrical power is produced by a fuel cell, the DC power is converted to AC power and stepped up to make it compatible with the facility's internal power grid. If the ECD 360 is an engine, the AC power produced is stepped up via the switchgear. The connection to the facility's power grid, a protected bus that enables the device 300 to be self-supporting for emergency shutdown, is through connector 371.

[0029] The above descriptions of the process identify certain preferred embodiments, which are not meant to be limiting in the application of the devices described.

[0030] Each embodiment references an optional multiple stage filtration system. This filter is intended to remove any organic and inorganic particulates that may contaminate the ECD or the reformer. Some VOC sources may not contain particulates, and some ECDs may have tolerance for some particulates, therefore, the filtration system may not be needed in some applications of the process.

[0031] The concentrator is described as a moving system in which the adsorbent material is transported from adsorption portions to desorption portions. It is recognized that this can be accomplished by a fluidized bed system or a system of adsorbent material attached to a rotating wheel. Also, the concentrator could be configured such that the adsorbent material is arranged in fixed beds and adsorption and desorption are variously alternated by controlling valves that direct the source gas flow and effluent fuel flow. The concentrator should be capable of desorbing VOC in a non-oxidizing environment, of separating the desorbed effluent from the clean gas leaving the adsorber, and be capable of concentrating the VOC such that the desorbed effluent has a hydrocarbon concentration above 15,000 PPM VOC. The sweep gases can be inert gases, steam, or fuel such as methane or another alkane, such that the sweep gas does not contain free oxygen, which could react in the desorption step with the hydrocarbons present in the device.

[0032] The ATR Reformer also may contain various alternatives. Auto Thermal reforming is made up of two process steps: partial oxidation and steam reforming. A simple steam reformer may be used for simple VOC fueling some ECDs, but more complex reforming, utilizing water-gas shift reactions and/or preferential oxidation, may be necessary for certain generators such as Proton Exchange Membrane fuel cells. Also, plasma arc decomposition may be suitable for some fuels.

[0033] It will be apparent that the device described in this invention is constructed from commercially available components, which when operated in the particular combinations described above, form a device that generates electricity from the waste gas stream of certain manufacturing processes. The embodiments described above result in a variety of fuel types to be used in fuel cells, engines, turbines, or other ECDs including: reformed hot gaseous fuel, and reformed cold gaseous fuel. The fuel desired will direct the choice of components in the device.

[0034] The embodiments of the invention and the types of fuel described above are not intended to limit the application of the invention. The components of the device can be recombined in other variations without departing from the concept of this invention. It is not intended to limit the application of the invention except as required by the following claims.

[0035] Various preferred embodiments of the invention have been described in fulfillment of the various objects of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.