U.S. patent application number 12/117886 was filed with the patent office on 2008-11-20 for cooling system for carpet/wood ash.
This patent application is currently assigned to Siemens Building Technologies, Inc.. Invention is credited to Dan Shabo, Emily Tuzson.
Application Number | 20080282944 12/117886 |
Document ID | / |
Family ID | 40026225 |
Filed Date | 2008-11-20 |
United States Patent
Application |
20080282944 |
Kind Code |
A1 |
Tuzson; Emily ; et
al. |
November 20, 2008 |
COOLING SYSTEM FOR CARPET/WOOD ASH
Abstract
A method and system transfer, cool, store, and load an ash waste
product of a gasification process. Hot ash is moved toward a
storage silo via one or more augers and/or conveyors. Ash may be
sent through a means for reducing the size of any ash chucks, such
as roller crushers. The ash may be transferred via a first auger
affixed with a glycol/water indirect cooling means. The ash may
then be transferred to a second auger, also having a glycol/water
indirect cooling means, but further being operable to blanket the
ash with an inert gas, such as slightly pressurized nitrogen. Then,
the ash may be transferred to a storage silo via a continuous flow
bucket conveyor. The silo and conveyor may be operable to maintain
the ash blanketed with inert gas. Subsequently, the ash may be
unloaded from the silo, such as into a vehicle, via a retractable
spout.
Inventors: |
Tuzson; Emily; (Cleveland
Heights, OH) ; Shabo; Dan; (White, GA) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Assignee: |
Siemens Building Technologies,
Inc.
Iselin
NJ
|
Family ID: |
40026225 |
Appl. No.: |
12/117886 |
Filed: |
May 9, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60938310 |
May 16, 2007 |
|
|
|
Current U.S.
Class: |
110/259 ;
110/165R |
Current CPC
Class: |
F23J 1/00 20130101; F23G
7/105 20130101; F23J 2900/01003 20130101 |
Class at
Publication: |
110/259 ;
110/165.R |
International
Class: |
F23J 1/02 20060101
F23J001/02 |
Claims
1. A method of transferring a waste product generated from a
thermal conversion process, the method comprising: transferring
and/or storing a waste product of a gasification process under a
blanket of inert gas.
2. The method of claim 1, the method comprising crushing the waste
product with a roller crusher, such that extinguishing smolders
within the waste product is facilitated by the inert gas displacing
oxygen in the vicinity of the waste product.
3. The method of claim 1, the method comprising transferring the
waste product with a continuous bucket conveyor to a storage
unit.
4. The method of claim 3, the method comprising unloading the waste
product from the storage unit via a retractable spout.
5. The method of claim 3, the method comprising unloading the waste
product from the storage unit into a mobile receptacle, the mobile
receptacle being under a second blanket of inert gas.
6. The method of claim 1, wherein the blanket of inert gas is
applied to the waste product in a glycol/water mix indirect cooled
auger that cools the waste product as it is being transferred.
7. The method of claim 1, wherein the inert gas is nitrogen.
8. The method of claim 1, the method comprising: shredding a fabric
material having a backing; separating the shredded fabric material
into primarily fabric and primarily backing components; gasifying
the primarily fabric component in a gasifier, the gasifier
producing steam; and generating ash as the waste product of the
gasification process.
9. A method of transferring a waste product generated from a
thermal conversion process, the method comprising: crushing a waste
product of a thermal conversion process with a roller crusher;
blanketing the waste product with an inert gas; and transferring
the waste product with a continuous bucket conveyor to a storage
unit.
10. The method of claim 9, the method comprising unloading the
waste product from the storage unit via a retractable spout.
11. The method of claim 9, wherein the blanket of inert gas is
applied to the waste product in a glycol/water mix indirect cooled
auger that cools the waste product as it is being transferred.
12. The method of claim 9, wherein the waste product is placed
under a blanket of inert gas during unloading from the storage
unit.
13. The method of claim 9, wherein the waste product is placed
under a blanket of inert gas during storage in the storage
unit.
14. The method of claim 9, wherein the inert gas is nitrogen.
15. The method of claim 9, wherein the thermal conversion process
is a gasification process that accepts a combination of primarily
carpet fabric material and wood flour as a biomass fuel and the
waste product is ash generated from the gasification process.
16. The method of claim 9, the method comprising: shredding a
fabric material having a backing; separating the shredded fabric
material into primarily fabric and primarily backing components;
gasifying the primarily fabric component in a gasifier, the
gasifier producing steam; generating ash from gasification as the
waste product.
17. A system for transferring a waste product generated from a
thermal conversion process, the system comprising: a roller crusher
operable to crush a waste product of a thermal conversion process;
and means for blanketing the waste product with an inert gas.
18. The system of claim 17, the system comprising: a continuous
bucket conveyor operable to transfer the waste product to a storage
unit; and a retractable spout operable to unload the waste product
from the storage unit.
19. The system of claim 17, wherein the thermal conversion process
is a gasification process that accepts a waste carpet fabric and
wood flour mixture as a biomass fuel, the waste product is ash
generated from the gasification process, and the inert gas is
nitrogen.
20. The system of claim 17, wherein the means for blanketing the
waste product with an inert gas includes one or more conveyors
and/or augers operable to transfer the waste product and blanket
the waste product with nitrogen.
21. The system of claim 17, wherein the means for blanketing the
waste product with an inert gas includes a storage unit being
operable to blanket the waste product with nitrogen.
Description
PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of the filing date under
35 U.S.C. .sctn. 119(e) of Provisional U.S. Patent Application Ser.
No. 60/938,310, filed on May 16, 2007, entitled "Cooling System for
Carpet/Wood Ash," which is incorporated by reference in its
entirety herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the production of
energy. More particularly, the invention relates to a method and
system for transferring, cooling, storing, and unloading ash
generated from a gasification process or other thermal conversion
process.
BACKGROUND OF THE INVENTION
[0003] Thermal conversion processes may generate waste products
that are difficult to dispose of. An exemplary thermal conversion
process is gasification. Gasification is the process of converting
solid carbonaceous or other biomass fuel into a synthetic gas. In
this process, the resultant "synthetic" gas may be burned to
produce steam.
[0004] The gasification process may produce ash. The ash may drop
from the bottom of the gasifier and contain a high amount of
carbon, which makes the ash somewhat combustible. The ash may
contain varying quantities of calcium oxide, which reacts
exothermically with water. The ash may exit the gasifier at high
temperatures, as the gasifier temperature may be at least
1600.degree. F. In typical biomass gasification systems, the ash
may be sprayed with water to reduce the temperature of the ash. Due
to the high carbon content of the ash, the ash may smolder and/or
ignite if not sufficiently moistened and/or cooled.
[0005] Several problems may result from known water spray ash
handling systems, including those identified directly below.
[0006] 1. When water is sprayed on the ash, a mud-like slurry may
be created. The mud may build up on various pieces of equipment,
including the inside of an ash or other waste product storage silo,
and eventually harden. The build up of mud may reduce the effective
size of the conveyance and storage equipment, as well as clog
rotating or moving equipment.
[0007] 2. When water is sprayed onto the ash, an exothermic
reaction may occur, re-igniting unconsumed carbon in the ash
stream.
[0008] 3. When water is not added to the system, clumps of ash,
which may include carbon, calcium oxide and pieces of melted
biomass fuel (such as melted carpet fibers in one aspect that uses
waste carpet as a biomass fuel), may continue to smolder after
introduction into the ash silo. This may re-ignite other unconsumed
carbon in the ash stream.
[0009] 4. When ash is unloaded from the silo into a covered truck:
(a) large amounts of hot ash may become airborne, creating a severe
dust hazard and greatly reducing visibility during the ash
unloading process; (b) the hot, moist air from the wetted ash may
emerge from the truck openings, creating a hazardous stream of very
hot gases (the steam itself may be a burn hazard for system
operators, and the steam may further reduce visibility while
unloading the ash from the silo into the truck); and (c) during ash
unloading, ash may ignite, both in the silo and as it passed from
the silo into the truck receptacle, creating a burn hazard during
the ash unloading process.
BRIEF SUMMARY
[0010] The present embodiments provide a method and system for the
transferring, cooling, storing, and unloading a waste product of a
thermal conversion process. For example, the method and system may
accept an ash waste product of a gasification process. The hot ash
received may be moved toward a storage silo via one or more augers
and/or conveyors. The ash may be sent through a means for reducing
the size of any ash chucks, such as roll or roller crushers. The
ash may be initially transferred via a first auger affixed with an
indirect glycol/water cooling means. The ash may then be
transferred to a second auger, also having an indirect glycol/water
cooling means, but further being operable to blanket the ash with
an inert gas, such as slightly pressurized nitrogen. The second
auger may transfer the ash to a continuous bucket conveyor that in
turn delivers the ash to a storage silo. Both the silo and bucket
conveyor also may be operable to maintain the ash blanketed with
inert gas.
[0011] Subsequently, the ash may be unloaded from the silo, such as
into a vehicle receptacle, via a retractable spout. Various relief
values may be employed to ensure safe operation. In one embodiment,
the gasification process accepts only carpet waste and wood as
fuel. For instance, a gasification system may convert industrial
carpet waste and wood flour/wastes into production steam, such as
disclosed by U.S. application Ser. No. 11/052,634, filed Feb. 7,
2005, which is incorporated herein by reference in its entirety.
The carpet may be shredded, mixed with wood flour and/or other
waste, and gasified.
[0012] In one aspect, a method transfers a waste product generated
from a thermal conversion process. The method includes transferring
and/or storing a waste product of a gasification process under a
blanket of inert gas.
[0013] In another aspect, a method transfers a waste product
generated from a thermal conversion process. The method includes
crushing a waste product of a thermal conversion process with a
roller crusher, blanketing the waste product with an inert gas, and
transferring the waste product with a continuous bucket conveyor to
a storage unit.
[0014] In another aspect, a system transfers a waste product
generated from a thermal conversion process. The system includes a
roller crusher operable to crush a waste product of a thermal
conversion process and means for blanketing the waste product with
an inert gas.
[0015] Advantages of the present invention will become more
apparent to those skilled in the art from the following description
of the preferred embodiments of the invention which are shown and
described by way of illustration. As will be realized, the
invention is capable of other and different embodiments, and its
details are capable of modification in various respects.
Accordingly, the drawings and description are to be regarded as
illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIGS. 1 and 1a are a schematic illustration of an exemplary
ash transfer, cooling, storage, and unloading system;
[0017] FIGS. 2 and 2a are a schematic illustration of another
exemplary ash transfer, cooling, storage, and unloading system;
[0018] FIG. 3 is a schematic illustration of an exemplary nitrogen
generation and storage system; and
[0019] FIG. 4 is a block diagram flowchart of one embodiment of a
method for transferring, cooling, storing, and unloading a waste
product generated from a thermal conversion process.
DETAILED DESCRIPTION
[0020] The present embodiments provide a method and system for
transferring, cooling, storing, and unloading a waste product of a
thermal conversion process. In one embodiment, the thermal
conversion process is a gasification process and the waste product
is ash generated from gasification. In another embodiment, the
biomass fuel used during the gasification process is a mixture of
carpet waste and wood flour, such as described by U.S. application
Ser. No. 11/052,634.
I. Exemplary Thermal Conversion Process and Biomass Fuels
[0021] The process of gasification may be used to generate steam,
such as application steam for use by turbines. Gasification is the
thermal conversion of a solid biomass fuel into a hot (over
1,000.degree. F.) synthesis gas that contains combustible gases,
such as methane, hydrogen, carbon monoxide, and/or other gases. In
the process of gasification, or the conversion of a solid biomass
fuel into a gas, there may be an insufficient amount of oxygen to
completely burn the biomass.
[0022] The purpose of gasification and the resultant process
conditions may be significantly different than the purpose and
operating conditions of an incinerator. In an incinerator, the
intent may be to totally burn the solid feed within the confines of
the incinerator. On the other hand, the intent of gasification may
be to produce a gas for use external to a gasifier, as well as
controlling the gasifier emissions to improve any impact on the
environment. Additionally, ash generated from gasification as a
by-product that is subsequently disposed in an engineered landfill
may be biologically inert depending upon which gasification process
is used, or at least not a significant source of toxins.
Gasification may result in significant material reduction, such
that required landfill space is reduced. Accordingly, the process
of gasification may have multiple environmental benefits.
[0023] In one aspect, a fabric material having a backing, such as
carpet, may be used as a biomass fuel for gasification. The term
"carpet" as used herein may encompass any item that has been
manufactured from at least two different types of material, one
material being a fabric or other covering and another material
being a synthetic material, such as rubber or a polymer. For
instance, carpet in this context may include standard floor carpet,
floor mats, wall coverings, rugs, and the like, as well as
industrial carpet waste and segregated, used post-consumer carpet
waste.
[0024] Carpet waste may be provided to the system in the form of
bales. In general, bales are the end product of a compaction
process that is used to decrease the volume that a material
occupies by increasing the density and weight. Bales are typically
bound with bands or wire to keep the baled material from
separating. Bales may be rectangular, square, round, or have other
shapes. Baled carpet may enhance the ease of the delivery and
movement of the waste carpet. Landfill owners and/or operators may
also provide incentives for baling of carpet to reduce the volume
requirement of the landfill. Alternatively, the carpet is loose or
not compacted.
[0025] The carpet waste may be shredded and substantially or mostly
separated into carpet fines and carpet fibers. The carpet fines may
have value as a raw material to the carpet manufacturer, and the
carpet fines are detrimental to a gasification process since there
is little available heating value. Therefore, the removal and
storage of carpet fines may have economic, environmental and/or
process efficiency value. The primarily carpet fines may be moved
within a first waste product stream to a first silo for storage.
The primarily carpet fibers may be used as a biomass fuel, either
alone or mixed with another biomass fuel component. The biomass
fuel may be utilized by a gasifier to produce synthetic gas and
generate hot ash as a by-product. Subsequently, the synthetic gas
may be used to produce electricity, such as via either a combustion
turbine or a synthetic gas burner and a boiler.
[0026] The ash produced from gasification may be moved within a
second waste product stream to a second silo for storage. The first
and second waste product streams may be distinct such that the
primarily carpet fines, isolated to the first waste product stream,
and the ash, isolated to the second waste product stream, remain
separated at least until the ash cools down to approximately the
melting point of the carpet fines.
[0027] Using carpet waste as a biomass fuel for gasification may
produce a number of benefits. For example, the use of waste carpet
to generate application steam may reduce reliance upon other
sources of energy, such as coal and natural gas, which are limited
in supply. Moreover, expending a significant portion of waste
carpet as a fuel during gasification may reduce the total volume of
waste carpet products that ultimately are deposited in landfills.
Therefore, the present invention may provide environmental benefits
that conventional steam generation processes or carpet disposal
methods lack.
[0028] Exemplary schematics of a gasification system are shown in
U.S. application Ser. No. 11/052,634.
II. Exemplary Transfer, Cooling, Storing, and Unloading System
[0029] The present embodiments relate to a method and system that
may safely transfer, cool, store and unload ash free of or without
a water spray. In an initial ash auger, ash may be indirectly
cooled using a screw auger with a central channel through which a
cooled glycol/water mix is passed The ash may then pass through a
roll or roller crusher, which breaks up smoldering embers. A rotary
air lock may allow the downstream components of the system to be
pressurized with nitrogen or other inert gas A second cooling auger
may transfer the ash into a continuous bucket elevator, which may
directly or indirectly move the ash toward or into a storage silo.
The second ash cooling auger, bucket elevator and silo may be
blanketed with an inert gas, such as nitrogen.
[0030] The two augers used to convey the ash from the gasifier to
the silo may both be indirectly cooled with a glycol/water mix.
Conventional glycol/water indirect cooled screw augers are known in
the material handling industry and may be used.
[0031] The first glycol/water indirect cooled auger may be kept at
ambient or slightly negative pressure. The first auger may be
designed to cool the ash enough such that the ash may be discharged
into a rotary air lock and/or roller crusher. In one aspect, the
first auger may feed the rotary air lock, and then the roller
crusher. Alternatively, the equipment order may be changed, such
that the roller crusher may be positioned before and come first
within the system, followed by the rotary air lock.
[0032] The purpose of the roller crusher may be to break up any
smoldering embers, allowing the embers to be extinguished by a
nitrogen, or other inert gas, blanketing system before reaching the
silo. The roller crusher may be a dual roll crusher and consist of
a pair of steel rollers, separated by a gap of approximately 1/4''
inch. Alternatively, the roller crusher may use either a larger or
smaller gap. One of the rollers may be fixed, and the other roller
may be mounted on a rigid spring such that some relief or movement
is provided in the event that non-crushable material or items, such
as a steel bolt, were to move through the system.
[0033] The roller crusher may be placed prior to the air lock. If
the roller crusher is placed in the nitrogen-pressurized area, then
both rollers may have to be fixed in place. For example, if one
roller is allowed to move, then nitrogen may leak out along the
shaft of that roller. By placing the roller crusher outside
(before) the nitrogen pressurized zone of the ash system, the
second roller may be moveable without nitrogen leakage
concerns.
[0034] After the roller crusher, the ash may move through a rotary
air lock. The remainder of the ash conveyance, storage and
unloading system may be at least slightly pressurized with
nitrogen, or other inert gas, to eliminate and/or reduce smoldering
and/or combustion of the ash. Nitrogen, or another inert gas, may
be introduced into the system at various points along the system.
In one aspect, nitrogen is introduced into the second glycol/water
indirect cooled screw conveyer, the bucket elevator, and the
silo.
[0035] Once the ash passes through the rotary air lock, the ash may
be conveyed to the bucket elevator by the second glycol/water
indirect cooled screw conveyor/auger. The second conveyor may
further cool the ash.
[0036] The bucket elevator may be a continuous flow bucket
elevator, rather than a centrifugal bucket elevator. A centrifugal
bucket elevator may move very quickly and sling the product out of
the buckets and into the discharge chute. This process may chum up
the ash and increase the possibility of ash combustion. On the
other hand, a continuous bucket elevator may move much more slowly,
tipping over the full buckets and allowing gravity to empty them.
The continuous bucket elevator may minimize the amount of ash that
will become airborne in the silo, as well as reduce the likelihood
of combustion within the silo.
[0037] The present embodiments also include a modified silo
unloading process and equipment to ensure that the ash may be
safely discharged from the silo into an enclosed truck. The silo
unloading process may be free of, i.e., not use, a final water
spray when the ash moved from the silo into a truck receptacle
below. Instead, the system and method may include a retractable
discharge spout with an annular vent space. The retractable
tube-within-a-tube may extend from the bottom of the silo to the
truck. The dry ash may fall into the truck via the center tube of
the spout. An annular space surrounding the tube may suck a mixture
of nitrogen and air out of the truck as the ash falls, providing
pressure relief. The use of this type of retractable discharge
spout may eliminate the previous problem of dust blowing up out of
the truck as the ash was loaded into it. A bag-house dust collector
may remove the ash from this air stream. Nitrogen may be used to
pulse or shake the bags, so that the protective nitrogen blanket
extends all the way to the bag house.
[0038] Prior to ash unloading, the enclosed truck container may be
purged with nitrogen for a period of time, such as for
approximately ten minutes. The nitrogen purge may ensure that there
is little oxygen in the truck receptacle when the ash is loaded
into it. The nitrogen purge and accompanying oxygen removal may
reduce the likelihood of any remaining embers or hot spots igniting
the ash when the truck receptacle is filled.
[0039] This ash cooling system may work well for any ash that, for
whatever reason, cannot be easily cooled with a water spray system.
Powdery ash, that would create a plaster-like coating on equipment
when moistened, or ash that otherwise has chemical or physical
constraints that may eliminate the possibility of a water spray
system, could benefit from this ash cooling method.
[0040] Therefore, the present embodiments may use a unique
combination of equipment that provides for and includes: (1) a
roller crusher, (2) nitrogen blanketing of an ash system, either
completely or a portion thereof, (3) a continuous bucket conveyor,
and (4) a retractable ash spout. The present embodiments may
implement this equipment simultaneously and in various combinations
to handle an ash cooling and storage situation.
III. Exemplary Ash Storage and Transfer
[0041] FIG. 1 illustrates an exemplary waste product transfer,
cooling, storage, and loading system 100. The system 100 may
include an ash conveyor 102, a first auger 104, a second auger 106,
a continuous bucket conveyor 108, a storage silo 110, and a
nitrogen supply system 122. The system may include additional,
fewer, or alternate components.
[0042] The ash conveyor 102 may accept ash produced from a
gasification process and transfer the ash to a first auger 104. The
first auger 104 may be a first ash screw auger. A cooled
water/glycol mix may pass through the center of the screw, thus
cooling the ash that is moved through the auger 104.
[0043] The air lock 118 may separate the nitrogen-pressured portion
of the ash system from the slightly negatively pressurized
gasification unit and first ash cooling screw auger 104. The air
lock 118 may be repositioned to be above or below the roller
crusher 120. The roller crusher 120 may reduce or eliminate any
chunks of smoldering ash. FIGS. 1 and 1a together illustrate that
the sequencing of the air lock 118 and roller crusher 120 may be
interchangeable. In a preferred embodiment, the roller crusher 120
is positioned prior to or upstream of the air lock 118.
[0044] After passing through the air lock 118 and roller crusher
120, the ash may be transferred to a second auger 106. The second
auger 106 may be a second ash screw auger. Like the first auger
104, a cooled water/glycol mix passes through the center of the
screw, thus cooling the ash that is moved through the second auger
106. Alternatively, the cooled glycol/water mix may pass through an
outer jacket or sleeve associated with the second auger 106. The
second auger 106 may be slightly pressurized with nitrogen, such as
up to a few inches of water column to displace oxygen, to smother
any burning embers. In one aspect, nitrogen is used as a
non-flamable gas. Other inert gases may be used, such as carbon
dioxide, neon, helium, argon, krypton, xenon, radon, noble gases,
or other gases operable to displace oxygen. The term inert gas used
herein shall include noble gas. Any non-flamable gas operable to
displace oxygen may be used.
[0045] As shown, a cooling glycol/water supply 114 and cooling
glycol/water return 116 may be provided. The supply 114 may send
cooling glycol/water into a center sleeve (or alternatively an
exterior jacket around the interior) of either the first 104 or
second 106 augers, or both. The return 116 may receive spent
cooling glycol/water from the first 104 and/or second 106 auger.
Nitrogen 122, or other inert/noble gas, may be supplied to the
second auger 106.
[0046] The second auger 106 may transfer ash or other waste
products to a continuous-flow ash bucket elevator 108. The bucket
elevator 108 may be slightly pressured with nitrogen (or other
inert or noble gases). Explosion panels may be installed on the
sides of the elevator 108, to allow for safe pressure relief in the
event of a high-pressure incident.
[0047] A pressure relief valve 124 may be positioned at the top of
the bucket elevator 108. The relief valve 124 may allow for safe
pressure relief in the event of a high-pressure incident.
[0048] The ash may be transferred to an ash silo 110 via the bucket
elevator 108 directly, or indirectly via an intermediate
conveyor/auger 132. The ash silo 110 may be slightly pressured with
nitrogen via the nitrogen supply 122. The ash silo 110 may have an
emergency pressure relief valve 130 located at or near the top of
the silo 110. The relief valve 130 may ensure that, if there was a
high-pressure incident in the silo 110, the pressure would vent
safely through the top of the silo 110.
[0049] The silo 110 may have a secondary pressure relief valve 128
at or near the top of the silo 110 that may relieve the silo
pressure if the silo pressure was abnormally high, but not high
enough to trigger an emergency venting via the primary emergency
pressure relief valve 130. The silo 110 may have a dust collector
126 at or near the top of the ash silo 110. The dust collector 126
may operate to protect the pressure relief valve 128 at the top of
the silo 110.
[0050] The silo 110 may have a set of three vibratory shakers 132
that facilitate the movement of the ash from the silo 110. The
bottom of the silo 110 may have an air lock 134 that allows for the
silo 110 to be pressurized, and prevents the nitrogen supplied from
the nitrogen supply 122 from escaping through an unloading spout
134 when the unloading spout 134 is not in operation.
[0051] The bottom of the silo 110 may be associated with the ash
unloading spout 134. The unloading spout 134 may allow for clean,
safe and easy discharge of the ash, or other waste products, from
the silo into an ash or other container 112. The unloading spout
134 may be retractable and may include an annular vent space. In
one embodiment, the spout 134 may function as a retractable
tube-within-a-tube and may extend from the bottom of the silo to
the truck receptacle during use. The dry ash may fall into the
truck receptacle via a center tube of the spout 134. The annular
space surrounding the center tube may vent gases, such as a mixture
of nitrogen and air, out of the truck receptacle as the ash falls,
providing pressure relief and dissipation of gasses into the
atmosphere.
[0052] The unloading spout 134 may have an associated dust
collector 136. The dust collector 136 may capture the relief air
that passes through the unloading spout 134, and removes airborne
particulate from the relief air.
[0053] The nitrogen supply 122 line may include various fire
suppression techniques that consume nitrogen. These may include
nitrogen lines extending to various dust collector bags. Because
the dust collector(s) may be in the nitrogen-pressurized area, it
may be preferable to use compressed nitrogen for bag cleaning,
instead of compressed air.
[0054] One nitrogen supply 122 line may go toward a truck purge,
operable to fill the ash container with nitrogen prior to ash
unloading. Note that this line may receive high or low pressure
nitrogen. Another nitrogen supply 122 line may go to a roller
crusher, to pressurize the roller crusher and ash cooling auger
with nitrogen. Another nitrogen supply 122 line may go to the
bottom of the ash bucket elevator, to pressurize the bucket
elevator and ash cooling auger with nitrogen. A number of nitrogen
supply 122 lines, such as four or more, may go to the ash silo 110
to pressurize the ash silo 110 with nitrogen.
[0055] In one embodiment, the ash conveyor 102, the first auger
104, the second auger 106, the rotary air lock 118, the dual roller
crusher 120, and the bucket elevator 108 may be operable to
transfer ash at a rate of 2,000 lbs/hr. The roller crusher 120 may
use a 20 horse power, 1,800 rpm motor. The rotary air lock 118 may
use a 1.5 horse power, 1,800 rpm motor. The first and second augers
104, 106 may each use a 5 horse power, 1,800 rpm motor. The bucket
elevator 108 may use a 3 horse power, 1,800 rpm motor. The ash silo
110 may have a 12 feet diameter and 25 feet length, providing for
3,000 cubic feet of storage. The discharge air lock 134 may be
operable to discharge ash at a rate of 28,000 lb/hr. The discharge
rotary air lock 134 may use a 2 horse power, 1,800 rpm motor. The
vibratory dust collectors 132 may have associated 1.0 horse power,
3,500 rpm motors.
[0056] FIG. 2 illustrates another exemplary waste product transfer,
cooling, storage, and unloading system 200. Specifically, FIG. 2
shows another exemplary view of the physical positions of the
different pieces of equipment, and how the transfer, cooling,
storing, and unloading system components may be incorporated
into/interconnected with a gasification system. The system 200 may
include a storage unit 202, a conveyor 204, a gasifier 206, a
startup burner 208, a vent stack 210, a duct 212, a cyclone 214, a
second conveyor 216, a first auger 218, an air lock 220, a roller
crusher 222, a second auger 224, a continuous conveyor 226, a
storage unit 228, a second air lock 230, and an unloading spout
232. The system may include an interconnected inert gas system (not
shown). The system may include additional, fewer, or alternate
components.
[0057] A biomass fuel may be stored in the storage unit 202 and
transferred via a conveyor 204 into a gasifier 206 interconnected
with a startup burner 208. The gasifier 206 may have a vent stack
210 and ducting 212 leading to a cyclone 214. The cyclone 214 may
be operable to deliver an ash waste product into a conveyor or
auger 216. The conveyor or auger 216 may transfer the ash to a
first auger 218 associated with an air lock 220 and roll crusher
222. FIGS. 2 and 2a together illustrate that the sequencing of the
air lock 220 and roller crusher 222 may be interchangeable. In a
preferred embodiment, the roller crusher 222 is positioned prior to
the air lock 220.
[0058] After the ash exits the first auger 218 and passes thru the
roll crusher 222, the ash may be sent to the second auger 224.
Downstream of the air lock 220, the system may be operable to
blanket the ash with nitrogen or another inert gas. The second
auger 224 may deliver the ash to the bucket elevator 226, which in
turns may transfer the ash to the silo 228. The silo 228 may have a
second air lock 230 such that the silo 228 may be operable to
expose the ash within the silo 228 to slightly pressurized nitrogen
or another inert gas. The bottom of the silo 228 may be associated
with a retractable unloading sprout 232.
[0059] The first auger 218, second auger 224, retractable spout
232, and other components shown in FIG. 2 may correspond to the
components shown and described above with respect to FIG. 1. Other
components may be used.
IV. Exemplary Nitrogen System
[0060] FIG. 3 illustrates an exemplary nitrogen generation and
storage system 300. The system 300 may include a nitrogen generator
302, a dryer/filter 304, a receiver 306, a trap 308, a compressor
310, and a tank 312. The nitrogen system may include additional,
fewer, or alternate components. Although FIG. 3 represents the
layout of nitrogen-generating equipment associated with one aspect
of the present embodiments, it should be noted that any method of
generating nitrogen or any other inert gas may used. For instance,
inert gas may be purchased from a supplier and stored within a
storage tank interconnected with the waste product transferring,
cooling, storing, and unloading system for subsequent use.
[0061] A compressor 310 may be used to generate compressed air
supplied to the nitrogen generation system. Compressed air
generated may pass through a dryer and/or a filter 304 to remove
moisture and/or impurities. Compressed air generated and dried may
be temporarily collected in a receiver 306. The receiver 306 may
have a trap or drain 308 to further remove moisture and/or
impurities from the system. The nitrogen generator 302 may convert
the compressed dry air into nitrogen gas. The storage tank 312 may
feed the nitrogen supply 122 lines of FIG. 1 and may be associated
with various valves for bringing the nitrogen supply system on and
off line.
V. Exemplary Method
[0062] FIG. 4 illustrates an exemplary method of transferring,
cooling, storing, and unloading a waste product of a thermal
conversion process 400. The method 400 may include roller crushing
a waste product 402, blanketing the waste product within at least a
portion of the system with an inert gas 404, transferring the waste
product within the system toward a storage unit via a continuous
bucket conveyor 406, and/or unloading the waste product from the
storage unit via a retractable spout 408. The method may be
accomplished using the embodiments and components discussed with
respect to FIGS. 1-3 above. The method may include additional,
fewer, or alternate steps.
[0063] In one aspect, the method may provide for the transfer, as
well as the cooling, storing, and/or unloading, of a gasification
waste product with the waste product being blanketed with an inert
gas. The method may include crushing the waste product with a
roller crusher, such that extinguishing smolders within the waste
product is facilitated by the inert gas displacing oxygen in the
vicinity of the waste product. After which, the method may include
(1) transferring the waste product with a continuous bucket
conveyor to a storage unit and (2) subsequently, unloading the
waste product from the storage unit via a retractable spout. The
waste product may be unloaded from the storage unit into a mobile
receptacle, such as a truck or railcar. The mobile receptacle may
under another blanket of inert gas before, during, and/or after
unloading.
[0064] The method may include applying the blanket of inert gas to
the waste product in one or more glycol/water mix indirectly cooled
augers that cool the waste product as the waste product is being
transferred. In one embodiment of the method, the inert gas is
nitrogen. Other gasses may be used.
[0065] Another embodiment of the method may include crushing a
waste product of a thermal conversion process with a roller
crusher, blanketing the waste product with an inert gas, and/or
transferring the waste product with a continuous bucket conveyor to
a storage unit. The method may include unloading the waste product
from the storage unit via a retractable spout. The blanket of inert
gas may be applied to the waste product in a glycol/water mix
indirect cooled auger that cools the waste product as it is being
transferred. Alternatively or in addition, the waste product may be
placed under a blanket of inert gas during unloading from the
storage unit and/or during storage in the storage unit such that
the waste product is prevented from re-igniting during unloading
and/or storage as oxygen in the vicinity of the waste product is
displaced from any smolders or embers of the waste product.
[0066] The method and system may use means for blanketing the waste
product with an inert gas, such as one or more conveyors and/or
augers operable to transfer the waste product and blanket the waste
product with an inert gas, a storage unit being operable to blanket
the waste product with an inert gas, and/or a mobile receptacle
being operable to blanket the waste product with an inert gas.
[0067] Although the above embodiments are described, there are many
possible equipment configurations which may be designed and
utilized. For example, the synthetic gas produced by the gasifier
shown in FIG. 2 may be fired in one or two stages and the flue gas
directed to a boiler to produce medium or high-pressure steam. The
high-pressure steam may then be used to drive steam turbines for
the production of electricity. Alternatively, the combustion of
cleaned synthetic gas in a combustion turbine also may generate
electricity.
[0068] In one aspect, the method may use carpet waste and wood
flour as a biomass fuel during a gasification process. The method
may include sizing a fabric material having a backing, such as by
shredding, cutting, tearing, or grinding the fabric material,
separating the shredded or sized fabric material into constituent
fabric and backing components, storing the backing component in a
first storage unit, storing the fabric component in a third storage
unit, optionally storing another biomass fuel component fuel
component in a fourth storage unit, optionally mixing the fabric
component with another biomass fuel component, gasifying the fabric
component, and storing the ash generated from gasification as a
by-product in a second storage unit. The method may have other
variations, including those with fewer, additional, or alternate
steps.
[0069] In one embodiment, carpet or another fabric material having
a backing is used as a biomass fuel component, such as disclosed by
U.S. application Ser. No. 11/052,634, which is incorporated herein
by reference in its entirety. The fabric material is shredded and
substantially separated into constituent backing and fabric
components. The backing component is stored in a first storage
unit. The fabric component may be mixed with another biomass fuel
component before introduction into a gasifier. The gasifier
produces synthetic gas, which is subsequently used to produce
steam. The hot ash generated as a by-product of gasification is
stored in a second storage unit. Each waste product may be confined
to a distinct waste path such that the waste products remain
isolated from each other, at least until the ash cools down to
approximately the melting point of the backing component.
[0070] In another embodiment, the method may include providing
fabric material having a backing, such as carpet, as a biomass fuel
for gasification, shredding or sizing the carpet into pieces
approximately one square inch in size, and substantially separating
or sizing the shredded carpet into primarily carpet fibers and
primarily carpet fines, such as by a vibratory separator or a step
separator. Subsequently, the primarily carpet fines may be moved by
one or more additional conveyors to a first storage unit and the
primarily carpet fibers may be moved to and stored in an
intermediate storage unit.
[0071] The method may further include providing the separated
carpet fibers as a biomass fuel to a gasifier and producing
synthetic gas from gasification and generating ash as a by-product.
The method also may include moving the ash generated from
gasification to a second storage unit, such as a silo. The ash may
be moved by at least one additional conveyor. The first and second
storage unit may each be part of a distinct waste product path such
that the separated carpet fines and ash are isolated from each
other for a period of time. As a result, neither waste product is
contaminated by or affected by the other waste product, at least
until the ash cools to or below the melting point of the carpet
fines.
[0072] The method may include mixing the separated carpet fibers
with one or more additional biomass fuel components before the
introduction of the biomass fuel into the gasifier. Any additional
biomass fuel component may be pre-sized and not require any cutting
or shredding. For example, the available additional biomass fuel
components may include agricultural residues or wood-based fuels,
such as pellets, wood chips, wood flour, or sawdust. The additional
biomass fuel components may be stored in a third storage unit
before mixture with the carpet fibers and subsequent introduction
into the gasifier.
[0073] The method may include cooling and scrubing the synthetic
gas produced by gasification, burning the synthetic gas in a
burner, and heating a boiler to generate application steam via the
burner. The method also may include preheating the boiler feedwater
by using an economizer. Alternatively, the synthetic gas may be
used by a combustion turbine or another utility to generate
electricity.
[0074] While the preferred embodiments of the invention have been
described, it should be understood that the invention is not so
limited and modifications may be made without departing from the
invention. The scope of the invention is defined by the appended
claims, and all devices that come within the meaning of the claims,
either literally or by equivalence, are intended to be embraced
therein.
[0075] It is therefore intended that the foregoing detailed
description be regarded as illustrative rather than limiting, and
that it be understood that it is the following claims, including
all equivalents, that are intended to define the spirit and scope
of this invention.
* * * * *