U.S. patent application number 15/620192 was filed with the patent office on 2017-11-30 for device for reforming a voc gas.
The applicant listed for this patent is Detroit Edison Company. Invention is credited to Patrick Ryan, Mark Wherrett, Jeffrey White.
Application Number | 20170341008 15/620192 |
Document ID | / |
Family ID | 34078448 |
Filed Date | 2017-11-30 |
United States Patent
Application |
20170341008 |
Kind Code |
A1 |
Ryan; Patrick ; et
al. |
November 30, 2017 |
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.
Inventors: |
Ryan; Patrick; (Sterling
Heights, MI) ; White; Jeffrey; (Dearborn, MI)
; Wherrett; Mark; (Canton, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Detroit Edison Company |
Detroit |
MI |
US |
|
|
Family ID: |
34078448 |
Appl. No.: |
15/620192 |
Filed: |
June 12, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13094496 |
Apr 26, 2011 |
9675922 |
|
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15620192 |
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10543425 |
May 10, 2006 |
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PCT/US03/19416 |
Jun 20, 2003 |
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13094496 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01B 2203/0844 20130101;
B01D 53/02 20130101; B01D 53/12 20130101; C01B 2203/84 20130101;
C01B 2203/142 20130101; C01B 2203/0244 20130101; C01B 2203/1258
20130101; C01B 2203/82 20130101; B01D 53/72 20130101; C01B 3/34
20130101; B01D 2258/0208 20130101; Y02E 60/32 20130101; C01B
2203/1211 20130101; B01D 53/06 20130101; B01D 2257/708
20130101 |
International
Class: |
B01D 53/02 20060101
B01D053/02; C01B 3/34 20060101 C01B003/34; B01D 53/06 20060101
B01D053/06; B01D 53/72 20060101 B01D053/72 |
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
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of application Ser. No.
13/094,496, filed Apr. 26, 2011, which is a Divisional of
application Ser. No. 10/543,425, filed May 10, 2006, which is the
National Stage of International Application No. PCT/US03/019416,
filed Jun. 20, 2003, each of the entire contents of which is hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The present invention is directed to a method and device for
converting Volatile Organic Compounds (VOC) into energy. More
specifically, the invention relates to a method and device that
concentrates a dilute hydrocarbon gas using a concentrator into a
gaseous or liquid concentrated fuel. The concentrated fuel is then
converted into a reformate using a reformer and converted into
energy through an energy conversion device.
BACKGROUND
[0003] Various manufacturing, agricultural, contamination
remediation and industrial processes produce a waste gas stream
having dilute hydrocarbon concentrations. Some applications include
those where the VOC is entrained in a solid or liquid media such as
contaminated soil or water. The VOC can be converted to gas and
separated from the solid or liquid media. Other processes produce
or contain gaseous VOC. A number of processes exist to burn or
oxidize the VOC, but the present invention is directed to
recovering energy. If the concentration or purity of the VOC is
sufficiently great and they are suitable to operate an Energy
Conversion Device (ECD), they may be directly supplied to the ECD.
In other cases, these dilute hydrocarbon concentrations are
sometimes insufficient in their energy content to efficiently
operate an ECD. ECDs include devices that convert chemical energy
into electrical or kinetic energy such as combustion engines
(internal or external), Stirling cycle engines, gas turbines, or
fuel cells. In other situations, the waste gas stream has
sufficient energy content to operate an ECD, but the form of the
hydrocarbon is such that the ECD requires extensive modification to
operate using the waste gas directly. For example, the waste gas
may include complex hydrocarbons of varying concentrations or
particulates. These gases may harm the ECD if they are not treated
or converted to reformate.
[0004] Manufacturing processes that produce waste gas streams with
a dilute hydrocarbon concentration are currently flared or burned
or supplied to an ECD as part of the combustion air. Flaring the
waste gas does not return any energy. Burning the waste gas
produces heat. Recovering electrical or kinetic energy is generally
much more valuable than recovered heat energy. GB patent
application 2364257, published Jan. 1, 2002, and incorporated
herein by reference, splits a gas stream having VOC into two
streams. The first stream is directed to the combustion air intake
of an engine and the second stream is directed to a combustion
unit. Exhaust heat from the engine mixes with and combusts the
second stream. This reference neither teaches concentrating the VOC
nor directing the VOC to the fuel intake of the engine. WO9530470,
published Nov. 16, 1995, and incorporated herein by reference,
teaches a device to burn VOC in an engine by having two
adsorption/desorption units so that the waste gas stream and engine
may operate independently of one another. The first unit may
collect and concentrate VOC as needed and the second unit supplies
VOC to the engine as needed. This reference and the GB reference
leave the VOC in the combustion air and do not feed the VOC to the
fuel intake of the engine. US 2002/0100277 published Aug. 1, 2002,
and incorporated herein by reference also teaches directing VOC to
an internal combustion engine, but the VOC is not concentrated by a
device. Their concentration is based on the vapor pressure of the
VOC in the container. VOC not directed to the engine are condensed
into a liquid by a chiller, but these liquefied VOC is not supplied
to the engine as a fuel. None of these references teach reforming
the concentrated VOC.
[0005] It is known that waste gases can be directly supplied to the
combustion or exhaust air of an engine. One commercially available
system supplies waste gases from an industrial operation to a
turbine engine. In a paper by Neill and Gunter, VOC Destruction
using Combustion Turbines, published September 2002, and
incorporated herein by reference, describes a device that combines
waste VOC with natural gas to operate a gas turbine. The gas
turbine produces electricity for the facility. The waste gases come
directly from the exhaust air of the industrial operation and are
supplied to the engine as part of the combustion air. The turbine
engine has a separate fuel source to supply the majority of the
fuel. The exhaust air provides a relatively low (200 to 5000 ppm of
unburned hydrocarbons and VOC) percentage of the energy content
needed to operate the engine. Devices like this require an external
fuel supply as part of the normal operation of the device. The
external fuel supply is not merely a part of start-up or load
leveling operation. These references teach directly supplying VOC
to the engine without filtering or reforming and require an engine
capable of consuming the VOC. By directing the VOC to the
combustion air, a very large engine/generator is needed. The
example given in Neill and Gunter is a 20MW turbine to abate
150,000 Standard Cubic Feet per Minute (scfm) of air.
[0006] U.S. Pat. No. 5,451,249, issued Sep. 19, 1995, and
incorporated herein by reference, teaches a device and method to
supply a gas stream from a landfill to be used as the fuel source
of a fuel cell. The natural gas component of the landfill gas is
desirable and the VOC contained in the landfill gas is removed and
is not used to supply fuel to the fuel cell. The U.S. Pat. No.
5,451,249 patent, describes heavy hydrocarbons as contaminant
fractions that must be removed from the gas stream prior to
reforming. Rather than teaching that the VOC is a contaminant, the
present invention utilizes these hydrocarbons as the feedstock for
the reformer.
[0007] The present invention is directed to a device and method to
utilize the energy from waste VOC by converting the VOC into
reformate for easier processing by the ECD. The present invention
is capable of producing higher value kinetic or electrical energy
from waste gases. The dilute VOC gas stream are organic compounds
that evaporate readily into air may contain straight chain,
branched, aromatic, or oxygenated hydrocarbons. The invention has
the dual advantage of abating the hydrocarbons while producing
electricity. More specifically, the dilute VOC presently considered
waste products are reclaimed from the gas stream and used to
generate electricity in a fuel cell, or via an internal or external
combustion engine, a Stirling cycle engine, a gas turbine or
another ECD that can produce electricity or kinetic energy. The
invention is an energy efficient method to utilize the hydrocarbons
entrained in the gas stream present in, or exhausted from,
manufacturing, industrial, agricultural, environmental, or refinery
processes.
SUMMARY
[0008] The present invention provides for a device and method for
producing a reformate. The device includes a concentrator that
concentrates a dilute VOC gas stream. The concentrated VOC is then
processed by a reformer into a reformate that is suitable to
operate an ECD. The device is operated by adsorbing the dilute VOC
onto an adsorbent media within a concentrator. The concentrator
increases the concentration of VOC per unit volume. The adsorbed
VOC is then desorbed to form a concentrated VOC fuel. The
concentrated VOC fuel may be either liquefied VOC or a gaseous
concentrated VOC fuel. The concentrated VOC fuel is then directed
to a reformer to be converted into reformate. The procedure
provides a process that efficiently utilizes the energy capacity
within the dilute VOC gas stream.
[0009] Most industrial concentrators desorb with hot air. Because
of the risk associated with allowing the concentration of
hydrocarbons to approach the Lower Explosion Limit (about 11/2%
hydrocarbon by volume), the concentrations associated with gases in
these devices never become sufficiently fuel rich for the desorbate
to act as the primary fuel for an ECD. As described in the
Background of the Invention, the dilute hydrocarbons are merely
supplied to an engine as part of the combustion air. The engine
requires a separate fuel supply to operate. Further, many waste
gases are not suitable to be used as fuel in the ECD. By reforming
these gases, they can be converted into a reformate which is more
easily consumed by the ECD.
[0010] The device receives waste gas from a manufacturing or other
process. If the gas is prone to contain particulates, it is
filtered through a multiple stage filtration device prior to being
concentrated. Then, the gas is directed into an adsorption chamber
where the VOC is removed from the waste stream onto an adsorbent
material. The adsorbent material 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 material does not exceed a
predetermined level. Heating the VOC laden adsorbent material
causes the VOC to flash to high temperature vapor, which is then
converted to reformate and directed to a fuel cell, engine or other
type of ECD. A fuel cooler or condenser may be used to further
process the fuel stream as necessary to prepare the fuel for
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.
[0011] A variety of ECDs may be utilized to convert the reformate
into energy. Generators may be used to convert kinetic energy into
electricity. In one embodiment, the dilute VOC laden gas stream
passes through optional multiple stage particulate filters and an
adsorption/desorption concentrator. VOC is stripped from the gas
and adheres to the adsorbent media. The clean gas is vented to
atmosphere or used elsewhere in the process, and inert gas passes
over the adsorbent material to desorb the VOC. The inert gas-VOC
mixture is routed to a condenser where it is cooled to condense the
VOC. The inert gas is then recycled back to the desorption chamber.
The cooled VOC, now condensed into a liquid, is directed to a
reformer to convert the VOC to H.sub.2 gas and oxides of carbon.
The gaseous fuel is then directed to the ECD.
[0012] In an alternative embodiment, the VOC laden gas stream
passes through optional multiple stage particulate filters and an
adsorption/desorption concentrator. VOC is stripped from the gas
and adhere to the adsorbent media. The clean gas is vented to
atmosphere or used elsewhere in the process and a sweep gas passes
over the adsorbent material to desorb the adhered VOC. The sweep
gas may be gases that do not react with or oxidize the adsorbed VOC
or the adsorption/desorption concentrator and include steam, inert
gas, combustion products, or a fuel such as methane or another
alkane. The concentrated sweep gas-VOC mixture then passes into a
reformer to convert the hydrocarbons into H.sub.2 gas and oxides of
carbon. The reformate is directed to the ECD.
[0013] In another embodiment, the VOC laden gas stream passes
through optional multiple stage particulate filters and an
adsorption/desorption concentrator. VOC is stripped from the gas
and adhere to the adsorbent media. The clean gas is vented to
atmosphere or used elsewhere in the process and a sweep gas passes
over the adsorbent material to desorb the adhered VOC. The
concentrated sweep gas-VOC mixture then passes into a reformer to
convert the hydrocarbons into H.sub.2 gas and oxides of carbon. The
reformate is then cooled in a fuel cooler. The cooled gaseous fuel
is directed to the ECD.
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.degree. 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.degree. 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.
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