U.S. patent application number 11/338946 was filed with the patent office on 2007-07-26 for rotating bed gasifier.
Invention is credited to LaVoy M. JR. Thiessen, Randall J. Thiessen.
Application Number | 20070169411 11/338946 |
Document ID | / |
Family ID | 38284176 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070169411 |
Kind Code |
A1 |
Thiessen; Randall J. ; et
al. |
July 26, 2007 |
Rotating bed gasifier
Abstract
The present invention includes a gasifier for gasifying fuels
having a container with a top, sidewalls and a bottom for
facilitating the gasifying process. One or more open vertical
shafts extend downward inside the container for allowing a
downdraft or updraft of air and fuel for the gasifying process. A
rotating bed is preferably included inside the container and below
the one or more shafts for receiving the fuel. The bed rotates
essentially perpendicular to the shaft to facilitate even heating
and gasifying of the fuel.
Inventors: |
Thiessen; Randall J.;
(Toledo, IA) ; Thiessen; LaVoy M. JR.; (Parker,
CO) |
Correspondence
Address: |
MCKEE, VOORHEES & SEASE, P.L.C.
801 GRAND AVENUE
SUITE 3200
DES MOINES
IA
50309-2721
US
|
Family ID: |
38284176 |
Appl. No.: |
11/338946 |
Filed: |
January 25, 2006 |
Current U.S.
Class: |
48/77 |
Current CPC
Class: |
C10J 2200/09 20130101;
C10J 2300/165 20130101; C10J 2300/0956 20130101; C10J 2300/1671
20130101; C10J 2300/1687 20130101; C10J 2300/093 20130101; C10J
3/26 20130101; C10J 2300/0916 20130101; C10J 3/005 20130101; C10J
2300/1807 20130101; C10J 3/86 20130101; C10J 2300/1675 20130101;
C10J 3/34 20130101; C10J 3/42 20130101; C10J 3/84 20130101 |
Class at
Publication: |
048/077 |
International
Class: |
C10J 3/68 20060101
C10J003/68 |
Claims
1. A gasifier for gasifying fuels comprising: a container having an
inside and an outside; an open air and fuel shaft extending into
the inside of the container; and a rotating bed located within the
inside of the container, below the air and fuel shaft.
2. The gasifier of claim 1 further comprising one or more fingers
extending from a lower portion of the fuel shaft.
3. The gasifier of claim 1 further comprising one or more fingers
extending upward from the rotating bed.
4. The gasifier of claim 1 further comprising a drive shaft
attached to the bed for rotating the bed.
5. The gasifier of claim 4 further comprising one or more fingers
extending outward from the drive shaft.
6. The gasifier of claim 1 further comprising an ash auger to
remove used fuel from the container.
7. The gasifier of claim 1 further comprising an elevator that
recycles used fuel back into the fuel shaft.
8. The gasifier of claim 1 wherein the rotating bed has sidewalls
extending upwardly.
9. A gasifier for gasifying fuels comprising: a container with a
top, sidewalls, and a bottom; a first open shaft extending down
inside the container; a second shaft inside the first shaft
creating a space between the first and second shafts for allowing a
draft of air and fuel for gasifying the fuels; and a rotating bed
inside the container, below the space between the first and second
shafts for receiving the fuel.
10. The gasifier of claim 9 wherein one of the shafts rotates with
the bed.
11. The gasifier of claim 9 further comprising one or more air
vents through a sidewall of the first and/or second shaft allowing
air to travel through the first and/or second shaft and to enter
the space between the first and second shaft to aid in the
gasifying process.
12. The gasifier of claim 9 further comprising an ash sump and a
device for recycling the fuel back through the gasifier.
13. The gasifier of claim 12 wherein the device for recycling the
fuel is an auger.
14. The gasifier of claim 9 wherein the bed has sidewalls extending
upward to help hold the fuel onto the bed.
15. The gasifier of claim 9 further comprising one or more fingers
extending from a lower portion of the first and/or second shaft for
mixing the fuel.
16. The gasifier of claim 9 further comprising one or more fingers
extending upward from the rotating bed for mixing the fuel.
17. The gasifier of claim 9 further comprising a drive shaft
attached to the bed for rotating the bed.
18. The gasifier of claim 9 further comprising one or more fingers
extending from the drive shaft for mixing the fuel.
19. A method of gasifying biomass fuel comprising: inserting
biomass fuel into a fire tube of a gasifier; supplying heat and air
to the fuel; and stirring the fuel to promote uniform gasification
of the fuel.
20. The method of claim 19 wherein the stirring of the fuel is by
rotating a bed which is supporting the fuel.
21. The method of claim 20 wherein the bed rotation is about 1/4
revolution per minute.
22. The method of claim 19 further comprising recycling fuel into
the fire tube.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to an apparatus for
providing a more effective and efficient gasifier apparatus. More
particularly, although not exclusively, the present invention
relates to a rotating bed gasifier apparatus.
[0002] Currently, there are many types of gasifier systems.
Typically the gasification process is the primary energy generation
means. Gasification generally takes materials, such as wood, coal,
charcoal, agricultural residues, energy crops, municipal solid
waste or other biomass materials, and gasifies them to make a "gas"
used for power or electricity generation or other uses, such as
heat production. A typical gasification system consists of a
gasifier unit, a filtering system, and an energy converter.
[0003] Steam boiler/combustor units are also well-known, though
their use for primary energy generation has been questionable for
some time, mainly because of the harmful resultant emissions. A
steam boiler/combustor creates high pressure steam used for power
generation. Prior art systems apply steam boiler/combustor units as
secondary energy generation means to gain energy and thus increase
efficiency and reduce pollutants such as gasses produced during the
gasification process. An example of this type of system can be
found in U.S. Pat. No. 6,637,206 to Thiessen, which is herein
incorporated by reference in its entirety.
[0004] One problem with fixed bed gasifiers is that there are
inherent "hot spots" in the fuel, causing uneven gasifying. Some of
these systems add moving fingers to the fixed bed to agitate the
fuel to aid in the gasification process. The torque force on the
fingers increases as the diameter of the fire tube holding the fuel
increases. This limits the size of the gasifier which can be
constructed. By creating too large a gasifier, these fingers or the
shaft holding them bend and break during the agitation.
[0005] U.S. Pat. No. 2,226,927 to Rundstrom is an up-draft gasifier
which uses a grate system which reciprocates vertically, up and
down, within a fixed bed core to maintain an even flow of fuel and
gas and allow for the removal of ash. A problem with these
vertically reciprocating beds and fixed bed gasifiers is that the
larger the gasifier, the more chance for uneven heating inside the
gasifier and thus poor gasifying of the fuel.
[0006] Thus, in view of the foregoing, it is desirable to have an
improved gasifying system that solves these and other problems of
the prior art.
[0007] Therefore, the primary feature or advantage of the present
invention is an improved gasifier.
[0008] Another feature or advantage of the present invention is the
provision of a gasifier which reduces the size limitations in which
a gasifier fuel mixer can be built.
[0009] Another feature or advantage of the present invention is the
provision of a gasifier that more uniformly heats the material
being gasified to improve efficiency.
[0010] Another feature or advantage of the present invention is the
provision of a gasifier that improves air flow to the fuel.
[0011] Another feature or advantage of the present invention is the
provision of a gasifier that preferably includes a rotating bed, is
economical to manufacture, durable in use and efficient in
operation.
[0012] These and the other features or advantages of the present
invention will be apparent from the specification and claims that
follow.
BRIEF SUMMARY OF THE INVENTION
[0013] One or more of the foregoing features or advantages may be
achieved by a gasifier having a container with a top, sidewalls,
and a bottom for facilitating the gasifying process. An open
vertical shaft extends down from the top of the container and
allows a downdraft or updraft of air to mix with fuel for the
gasifying process. A rotating bed inside the container preferably
located below the shaft receives the fuel; the bed rotates
essentially perpendicular to the shaft.
[0014] A further aspect of the present invention involves one or
more fingers extending from a lower portion of the shaft for mixing
the fuel with the air. The present invention may also include one
or more fingers which extend upward from the rotating bed for
mixing the fuel with the air. The present invention also preferably
includes a shaft attached to the bed for rotating the bed.
[0015] Another aspect of the present invention is an ash auger for
removing used fuel from the container. Yet another aspect of the
present invention is the provision of a gasifier which recycles the
used fuel back into the shaft for reusing the fuel. Another
provision of the present invention is a gasifier having a bed with
sidewalls extending upward to hold the fuel onto the bed.
[0016] One or more of the foregoing features or advantages may be
achieved by the gasifier having a container with a top, sidewalls,
and a bottom for facilitating the gasifying process, a first open
vertical shaft extending inside the container, a second open
vertical shaft inside the first vertical shaft creating a space
between the first and second shafts for allowing a downdraft of air
and fuel for the gasifying process in the space between the first
and second shafts, and a rotating bed inside the container, below
the space between the first and second shafts for receiving the
fuel, the bed rotating essentially perpendicular to the shafts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows one embodiment of a gasifier system assembly
for using a gasifier to create energy.
[0018] FIG. 2 shows a cut away view of one embodiment of a
downdraft rotating bed gasifier.
[0019] FIG. 2A shows the gasifier of FIG. 2 configured as an
updraft gasifier.
[0020] FIG. 3 shows a top view of one embodiment of the vertical
shaft shown in FIG. 2.
[0021] FIG. 4 shows a top view of one embodiment of the rotating
trough or bed shown in FIG. 2.
[0022] FIG. 5 shows a cut away view of another embodiment of a
rotating bed gasifier.
[0023] FIG. 6 shows a top view of one embodiment of the rotating
bed shown in FIG. 5.
[0024] FIG. 7 shows a cut away side view of yet another embodiment
of a rotating bed gasifier.
[0025] FIG. 8 shows a top view of one embodiment of the rotating
bed shown in FIG. 7.
[0026] FIG. 9 shows a cutaway view of still another embodiment of a
rotating bed gasifier.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0027] The present invention relates to a rotating bed gasifier.
The present invention can be used in a system such as the system 10
as shown in FIG. 1. However, the present invention can be used in
any type of system where a gasifier for gasifying solid fuels is
desired.
[0028] Referring now to FIG. 2, a cut away side view of one
embodiment of a rotating bed gasifier assembly 20 is shown. The
gasifier assembly 20 begins with a gasifier container assembly 22.
The gasifier container assembly 22 generally has a cylindrical
shaped sidewall 24. However, the sidewall 24 can be in any shape.
Connected to the sidewall 24 is a top 26 and a bottom 28.
Preferably, the bottom 28 is an inverted cone-shaped piece of metal
to allow used ashes and overflow fuel or char to fall to a central
point of an ash sump 30.
[0029] The ash sump 30 is connected to the bottom 28 of the
gasifier container assembly 22 preferably is connected to an ash
auger 32 for removing the fuel and ashes after they have been
through the gasification process and fallen to the bottom of the
gasifier assembly 20. The present invention may use an elevator 33
which takes the char or fuel from the auger 32 and recycles it back
into the gasifier assembly 20. This allows for the further
gasification of the char or fuel and creates a more efficient and
more complete gasification of the fuel in the gasifier 20. In
addition, less waste ashes have to be removed from the gasifier 20.
Therefore, more complete gasification of the fuel is completed. The
waste ashes can be separated from the char or fuel by an ash
separator 35. The ash separator preferably has a screen 39 for
separating the waste ashes from the char or fuel which is to be
recycled. Once separated, the ashes can be removed through the ash
output 41 and the reusable char or fuel can be sent through the
elevator 33.
[0030] The gas created by the gasification process in the gasifier
assembly 20 extracted from the gasifier 20 through one or more
ports 34. The gas can then be used as an energy source for other
systems.
[0031] Looking now at FIGS. 2 and 3, the gasifier assembly 20 has a
vertical shaft 36 which extends through the gasifier container
assembly 22 creating a fire tube 37. Preferably, the shaft 36 has
one or more fingers 38 extending from a lower portion of the shaft
36. The fingers 38 can extend at any angle from the shaft 36. The
fingers 38 allow for breaking up the fuel as it falls down and
enters the fire tube 37 and during the gasifying process.
[0032] Below the shaft 36 is a rotating trough/bed 40. The rotating
bed 40 is attached to a drive shaft 42 which is connected to a
sprocket or pulley 44 which is in turn connected to the motor 50
via another sprocket or pulley 52 and a chain or belt 54. There is
preferably a bearing (not shown) at the top and the bottom of the
drive shaft 42 to facilitate even rotation of the drive shaft 42
and long life. There may also be fingers 43 extending from the
drive shaft 42 to aid in mixing the fuel.
[0033] The motor 50 is preferably geared down so that the drive
shaft 42 and the rotating bed 40 rotate inside the gasifier
assembly at approximately one revolution every four minutes. This
rotating or revolving bed 40 allows for the solid fuel which rests
on the bed 40 and rotates with the bed 40 to revolve, thereby
creating more distribution of uniform heat within the circumference
of the fire tube 37. This is accomplished by moving the hot spots
within the solid fuel around inside the fire tube 37 thereby more
uniformly heating the inside of the fire tube 37. In addition, the
bed 40 can rotate intermittently and/or reverse directions.
[0034] Additionally, it is preferred, but not necessary, that the
bed 40 have sidewalls 46 to reduce the amount of fuel falling off
the bed 40 before it is thoroughly gasified. In other words, the
fuel should remain on the bed 40 until the gasified fuel becomes
high enough to fall over the sidewalls 46 and down to the ash sump
30. Furthermore, the bed 40 preferably has one or more fingers 48
extending upward from the bed 40 which allow the rotating bed 40
and the fuel to revolve and mix in a crossing path with the fingers
38 extending from the shaft 36. In other words, the fingers 38, 48
pass one another during revolution of the bed 40 and mix the fuel.
This aids in more thorough gasification of the fuel.
[0035] As shown in FIG. 4, preferably there are four spaced apart
fingers 48 on the bed 40. However, any number of fingers can be
used. Preferably, the fingers 48 extend upward at any angle from
the bed 40. In addition, the bed 40 can be made from solid sheet
metal, perforated metal, expanded metal, or any other material
capable of holding the fuel which is to be gasified. With or
without holes the rotating bed 40, 78, 120, the ash builds up in
the tray and falls over the side and into the gasifier's bottom for
removal.
[0036] FIG. 2A shows the gasifier assembly 20 configured as an
updraft gasifier with the air flow reversed. In this embodiment,
the air can enter the port 34, pass through the fuel and exit as a
gas upward through the fire tube 37. Other aspects of the gasifier
20 remain the same.
[0037] FIGS. 5 and 6 show another embodiment of a gasifier assembly
60. This gasifier assembly 60 operates similar to the gasifier 20
shown in FIG. 2. As shown in FIGS. 5 and 6, the gasifier 60 has a
gasifier container 62, with sidewalls 64, top 66 and bottom 68.
Preferably, attached to the bottom 68 is an ash sump 70 and an
auger 72 for removing the used ashes. In addition, an elevator or
other device can be used for recycling the used ashes into the
gasifier assembly 60. Again, the gasifier 60 preferably has one or
more ports 74 for allowing the gas created in the gasifier 60 to be
directed out of the gasifier 60 and used.
[0038] In the embodiment shown in FIGS. 5 and 6, the gasifier 60
has a shaft 76 extending downward or vertically into the gasifier
container 62 creating a fire tube 77. In the embodiment shown in
FIGS. 5 and 6, the gasifier assembly 60 has a rotating trough or
bed 78 connected to a drive shaft 80 for revolving the rotating bed
78 similar to that shown in the gasifier assembly 20 of FIGS. 2 and
2A. Support brackets 81 support the bed 78 to the drive shaft 80.
There is preferably a bearing (not shown) at the top and the bottom
of the drive shaft 80 to facilitate even rotation and long life.
Preferably, the drive shaft 80 has a sprocket 82 which connects to
a motor assembly 50 for rotating the bed 78. Again, it is preferred
that the bed 78 rotates approximately one revolution every four
minutes, however other rotations can be used with the present
invention. The rotating bed 78 has outside sidewalls 84 to help
hold the fuel onto the bed 78. However, the rotating bed 78 has
inside sidewalls 86 which extend up into the shaft 76, thereby
creating an elongated ring-shaped fire tube 77. This is best shown
in FIG. 6. By being constructed in this manner, air can draft
downward through the center of the inside sidewalls 86 and enter
through optional vents 88 to provide more air for the gasification
process. This type of rotating bed 78 also helps to reduce hot and
cold spots within the gasifier assembly 60. In addition, the added
air coming in through the vents 88 create improved gasification of
the fuel. In addition, this gasifier 60 can have updraft air
flow.
[0039] Still another embodiment of the rotating gasifier assembly
100 is shown in FIGS. 7 and 8. Here again, the gasifier assembly
100 has a gasifier container 102 with sidewalls 104, a top 106,
bottom 108, ash sump 110, auger 112, and port 114. The gasifier
assembly 100 shown in FIGS. 7 and 8 has a first vertical shaft 116
and a second vertical shaft 118 located concentrically inside the
first vertical shaft 116. This creates an elongated ring fire tube
117 as shown in FIG. 8, that is similar to that shown in FIG. 6.
However, the second shaft 118 does not rotate with the rotating
trough/bed 120. Downdraft air can enter the second vertical shaft
118 and pass through optional vents 119 to enter the fire tube 117
to aid in the gasification of the fuel. The rotating bed 120 is
attached to a drive shaft 122 by support brackets 123. There is
preferably a bearing (not shown) at both the top and the bottom of
the drive shaft 122 to facilitate even rotation and long life. A
motor assembly 50 or other similar type driving device is used for
creating the revolving motion of the rotating bed 120. It is
preferred, that the rotating bed 120 have outside walls 126 and
inside walls 128 extending upward from the rotating bed to reduce
overflow of the fuel until the gasifying process takes its
course.
[0040] It is understood that the rotating bed gasifier assemblies
20, 60, 100 can have different shaped or designed rotating beds 40,
78, 120, 142. In addition, the rotating bed 40, 78, 120 can be
created with sheet metal, perforated metal, expanded metal, or any
other material suitable for holding the fuel which is to be
gasified. Furthermore, the rotation of the bed 40, 78, 120, 142 can
be any appropriate speed or direction. It is preferred, however
that the speed of the rotating bed 40, 78, 120 not be so fast as to
reduce or impede the gasifying process.
[0041] The preferred fuel for this gasifier is shelled corn.
However other fuels can be used. Air is sucked, blown, or both
through the fuel which is heated and pyrolyzed, forming gas for the
gasification process. The gasification process is self-sustaining
with a blower (not shown) operating. The rotating bed 40, 78, 120,
142 replaces the function of a fixed grate in standard gasifiers in
the art. The gasification process generally continues until the
blower (not shown) or rotating bed 40, 78, 120 stops.
[0042] The direction of rotation of the rotating bed 40, 78, 120,
142 can be clockwise or counterclockwise. In addition, the bed 40,
78, 120, 142 can agitate or move intermittently, whatever motion
works best for the fuel which is being used. It is preferred that
the ring-type rotating troughs 78, 120 are used in place of the
pan-type rotating trough 40 once the specifications require the
rotating tray to be larger than approximately 36 inches in
diameter. This ensures better fuel agitation, which is necessary to
overcome the problems of biomass gasification. In addition,
ring-type troughs also increases the rate of gasification by
substantially increasing the reactive area in the gasifier 20, 60,
100. Rather than restricting the gas flow to the outside of the
ring, a ring-type trough may also allow gas to flow across the
inside of the ring, as best shown in FIG. 7. In addition to
reinforcing the rigidity of the rotating tray 78, 120, the braces
or brackets 81, 123 serve to move char/ash to the removal sump 70,
110 where it can be augured out by the auger 72, 112.
[0043] The recycling of char back into the fire tube 37, 77, and
117 uses a natural by-product of biomass gasification. Essentially,
the char/ash auger 32, 72, 112 is elevated back to the top of the
gasifier 20, 60, 100 and reintroduced/recycled by combining it with
new solid fuel or biomass fuel which is being fed into the gasifier
20, 60, 100 for the first time. This greatly reduces the amount of
ash produced in the process because it gets reused and further
reduced each time it is reused.
[0044] In addition to biomass fuel, plastic fuel can be combined
with biomass fuel to form a fuel blend. Because the plastic is a
petrol-chemical derivative, it bums much faster than the biomass
fuel. As a result, a filtering effect with this blended fuel can be
accomplished by introducing dirty gasses from petrol/fossil fuels
which are burned separately in a combustor similar to that as shown
as a gasifier system 10 in FIG. 1. Many dirty fuels cannot be
blended in this way because of metal which is contained within
them. Using dirty fuels with metallic contents would clog the
gasifier. Examples of such dirty fuels are tire fluff, medical
waste, and circuit boards. However, if the plastics/rubber are
homogeneous, blending them with biomass in the proper amount allows
their clean burning while increasing the energy output from the
gasifier. While any type of fuel can be used within the gasifiers
of the present invention, it is noted that petro-chemical derived
fuels cannot easily be gasified by themselves. These fuels melt
which in turn restricts the necessary air flow and therefore
severely limits or stops the gasification process.
[0045] It is widely known in the art that coal cannot generally be
downdraft gasified easily. Therefore, a gasifier assembly 140 is
shown in FIG. 9 as an inverted downdraft gasifier. This gasifier
assembly 140 works similar to the previously described gasifiers
20, 60, 100 with a rotating bed assembly 142. This gasifier
assembly 140 allows air to flow inward through one or more vents
144, through the fuel, and out through one or more ports 148. This
embodiment shows that either a top fuel inlet 150 or a bottom fuel
inlet auger 152 can supply fuel into the gasifier 140. The top fuel
inlet 150 allows for fuel to enter the gasifier assembly 140 and
fall downward into the fire tube 154 for gasification. The bottom
fuel inlet auger 152 similarly gets the fuel to the inside of the
fire tube 154, however, the bottom fuel inlet auger 152 uses a
mechanical auger for feeding the fuel into the fire tube 154. It is
preferred that the top input design would not be used if rubber or
plastic is mixed with the biomass fuel. In this case, it is
preferable that the bottom input design be used for the purpose of
combining biomass fuel with petrochemical derived fuels.
[0046] It is understood that even though specific references are
made to certain parts or sections of the invention in the figures,
these specific parts or figures or design styles can be
interchanged on any of the gasifiers as may be desired for a
specific situation. In other words, any of the features or designs
shown or contemplated can be used on any of the contemplated
gasifiers.
[0047] In the drawings and specification there has been set forth a
preferred embodiment of the invention, and although specific terms
are employed, these are used in a generic and descriptive sense
only and not for purposes of limitation. Changes in the form and
the proportion of parts as well as in the substitution of
equivalents are contemplated as circumstance may suggest or render
expedient without departing from the spirit or scope of the
invention as further defined in the following claims.
* * * * *