U.S. patent application number 14/842622 was filed with the patent office on 2016-06-09 for system and method for renewable fuel using sealed reaction chambers.
The applicant listed for this patent is Jon Strimling. Invention is credited to Jon Strimling.
Application Number | 20160160124 14/842622 |
Document ID | / |
Family ID | 48944450 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160160124 |
Kind Code |
A1 |
Strimling; Jon |
June 9, 2016 |
System and Method for Renewable Fuel Using Sealed Reaction
Chambers
Abstract
The system and method described herein provide for the higher
production rate fractionation of biomass for the purpose of
selectively separating specific volatile components, which may
subsequently be used in the production of a renewable liquid fuel,
such as gasoline. Increased production rates of processing of
biomass or other feedstock is achieved through the use of sealed
reaction chambers, which may be transferred in a sealed
configuration between stations in a multi-station processing
system. Also, the present invention considers the use of piston
assemblies for the dual functions of controlling fluid intake and
exhaust (in combination with valves) and for providing a more
robust and more cost effective sealing mechanism. The present
invention may also achieve improved uniformity of biomass
processing through the introduction of a mechanical agitator
designed to mix the biomass during processing.
Inventors: |
Strimling; Jon; (Bedford,
NH) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Strimling; Jon |
Bedford |
NH |
US |
|
|
Family ID: |
48944450 |
Appl. No.: |
14/842622 |
Filed: |
September 1, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13687449 |
Nov 28, 2012 |
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14842622 |
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61569058 |
Dec 9, 2011 |
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61569053 |
Dec 9, 2011 |
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61564195 |
Nov 28, 2011 |
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61564194 |
Nov 28, 2011 |
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Current U.S.
Class: |
202/110 ;
202/151 |
Current CPC
Class: |
C10B 37/00 20130101;
C10G 3/42 20130101; Y02P 30/20 20151101; Y02E 50/10 20130101; C10B
53/02 20130101; B01J 19/18 20130101; C10G 2300/1011 20130101; Y02E
50/14 20130101; B01J 7/00 20130101; C10B 27/06 20130101 |
International
Class: |
C10B 27/06 20060101
C10B027/06; C10B 53/02 20060101 C10B053/02; C10B 37/00 20060101
C10B037/00 |
Claims
1. A processing cartridge apparatus comprising: a sealable
container; a reaction chamber within the sealable container; a
sealable port for adding feedstock to the reaction chamber; and at
least one sealable fluid port operatively connecting the reaction
chamber to the exterior of the sealable container when the fluid
port is open.
2. The apparatus of claim 1, further comprising a movable member
dividing an interior volume of the sealable container to form a
control chamber and a reaction chamber, and a means of moving the
movable member so as to change the volume of the reaction
chamber.
3. The apparatus of claim 1, further comprising an agitator.
4. The apparatus of claim 1, further comprising a heater to control
a temperature of the feedstock
5. The apparatus of claim 1, wherein the reaction chamber is a
rotatable drum.
6. The apparatus of claim 1, further comprising an electrical
connection positioned on an exterior surface of the sealable
container and operatively connected to at least one electrical
component.
7. The apparatus of claim 1, further comprising at least one
temperature sensor positioned at least partially inside the
sealable container.
8. A system of fractionating biomass to extract volatile compounds
comprised of: one or more reaction chambers into which biomass may
be injected, the reaction chambers including mechanical means of
agitating the biomass, the reaction chambers being capable of
subjecting the biomass to a specified temperature and pressure
profile, wherein at least one reaction chamber comprising a port;
and a collection device for receiving volatile compounds as they
are released via at least one port.
9. The system of claim 8, further comprising a mixing element in a
reaction chamber.
10. The system of claim 8, further comprising a heater to control a
temperature of the reaction chamber.
11. The system of claim 8, further comprising a piston assembly,
wherein the piston assembly controls a volume of the reaction
chamber.
12. The system of claim 8, wherein at least one reaction chamber is
a piston-cylinder assembly.
13. The system of claim 8, further comprising a filter element
operatively connected to the at least one port.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/687,449, filed Nov. 28, 2012, and claims
the benefit of the following U.S. Provisional Patents Applications:
Ser. No. 61/564,194, titled "System and Method for Producing
Renewable Fuel Using Sealed Cartridges" filed Nov. 28, 2011; Ser.
No. 61/564,195, titled "System and Method for Producing Renewable
Fuel Using Stationary Pressure Chambers" filed Nov. 28, 2011; Ser.
No. 61/569,058, titled "System and Method for Producing Renewable
Fuel Using Sealed Cartridges" filed Dec. 9, 2011; and Ser. No.
61/569,053, titled "System and Method for Producing Renewable Fuel
Using Stationary Pressure Chambers" filed Dec. 9, 2011. All of
these applications are hereby incorporated by reference herein.
BACKGROUND
[0002] 1. Field of Invention
[0003] The invention relates to a system and method of using
stationary pressure chambers and sealed cartridges to produce
renewable fuel from biomass.
[0004] 2. Discussion of Related Art
[0005] During the production of renewable fuels, it is often
advantageous to react a fluid with solid materials for the purpose
of generating known reaction products in a controlled manner. It is
desirable that such processes subject the reactants to temperatures
and pressures which are as uniform, accurate, and precise as
possible. It is also desirable that variations in temperature occur
as evenly throughout the reactants as possible. In such cases it is
commonly required that the resulting products be collected
separately at various stages of processing. For example, in the
mechanical processing of an organic solid feedstock or reactant,
such as biomass, for the purpose of extracting volatile elements
for the production of liquid transportation fuels or other
purposes, it may be advantageous to control the temperature,
pressure and fluid composition of the environment surrounding the
feedstock in successive steps. Controlling such environmental
factors allows for the production and collection of different,
specific volatile elements in each step, rather than producing a
wide variety of relatively unusable reaction products all at
once.
[0006] In order to accurately control pressure and temperature
profiles, state-of-the-art methods, described by U.S. Patent
Publication Numbers 2010/0180805, 2011/0209386 A1, 2011/0177466 A1
and 2011/0212004 A1, which are incorporated herein in their
entirety, rely on trays carrying thin layers of compressed biomass
which move from station to station. These collective descriptions
of state-of-the-art methods represent a significant improvement
over traditional processes of pyrolysis, in that through the
methods described, the biomass materials are typically heated in
successive stations, each of which drives off specific volatile
compounds, which can then be more easily processed into renewable
fuels.
[0007] These state-of-the-art methods specifically referenced above
overcame a significant challenge of traditional pyrolysis, which
had been that in heating biomass in large batches over broad ranges
of temperatures, a wide variety of gaseous and liquid compounds
were produced in forms that were of mixed composition, and were
therefore difficult to further process to make renewable fuels.
This process had been further complicated by the thousands of
compounds in biomass feedstock, by the fact that the products of
pyrolysis are often not thermodynamically stable, and by the fact
that it had been difficult to consistently maintain narrow ranges
of pressure and temperature in three dimensional commercial
pyrolysis systems.
[0008] To maintain temperature and pressure uniformity at each
station in processing, the state-of-the-art methods utilize a thin
layer of compressed biomass, typically 1/8 of an inch thick, to
maintain temperature uniformity during heating. The benefit of this
thin, nearly 2-dimensional layer and processing the biomass in
narrow temperature range, the biomass can be selectively decomposed
in multiple stages at successive stations, with specific volatile
compounds released at each step of the process.
[0009] Biomass is typically comprised of a wide array of compounds
classified within the categories of cellulose, hemicelluloses,
lignin, starches, and lipids. These compounds go through multiple
steps of decomposition when subject to the pyrolysis process. For
example, hemicelluloses comprise C5 sugars such as fructose and
xylose, which yield furfural and hydroxymethylfurfurals upon
thermolysis. The latter compounds can be further converted to fuel
intermediates furan and tetrahydrofuran. The relatively narrow
temperature windows experienced within a processing station using
the current art allow for the collection of these useful
intermediates.
[0010] However, because the biomass layer must be limited to a thin
layer for uniformity of heating, scaling up production quantities
is more challenging that it would be for larger batches of
material, and therefore requires larger, more expensive equipment
and/or additional production lines. Furthermore, because
state-of-the-art methods and systems typically heat only surface of
the biomass layer and the compressed nature of the biomass layer
limits exposed surface area, heating and cooling remains
non-uniform despite the aforementioned thickness limitations.
Another drawback of state-of-the-art methodology is that the
reduced surface area created by compressing the biomass into a thin
layer also decreases the surface to volume ratio, and therefore
increases the time required to first heat, second produce the
desired reaction products, and third diffuse the reaction products
back into the fluidic environment. It should be noted that with the
state-of-the-art methods, the diffusion of volatile organic
compounds from the bottom layer of the layer of biomass is slowed
by the compression of that layer of biomass, which inhibits fluid
flow to and from biomass particles on the unexposed side of the
compressed layer of biomass.
[0011] To generate the proper operating environment,
state-of-the-art methods further require a flexible bellows to be
lowered over, and sealed to the top of, the tray at each processing
station. Such designs have been commonly employed in small scale
experimental uses, but are challenging to scale up for high volume
processing. Additionally, these bellows designs typically have
flexible seals which are susceptible to failure on repetitive
cycling, so while they are appropriate for short term experimental
use, they present reliability challenges at a commercial production
scale. This is particularly true in an environment with
supercritical fluids or volatile organic chemicals circulating,
which may damage the flexible members, and is also especially true
with high pressure differentials between stations, which increase
the stresses on the joints in a bellows assembly.
[0012] Further complications arise in state-of-the-art methodology
when moving materials from one high pressure environment to the
next, as from station to station during processing. Airlocks are
often necessary to prevent leakage of high pressure fluids, or to
stabilize pressure on either side of any seals prior to moving a
tray. The incorporation of such airlocks further increases cost and
decreases the mechanical reliability of equipment used to execute
state-of-the-art methods.
[0013] A need therefore exists for a scalable, lower-cost,
mechanically reliable, system and method of producing renewable
fuels capable of more uniform heat distribution and generating more
complete reactions in a reduced period of time.
SUMMARY
[0014] The system and method described herein provide for the
higher production rate fractionation of biomass for the purpose of
selectively separating specific volatile components, which may
subsequently be used in the production of a renewable liquid fuel,
such as gasoline. Increased production rates of processing of
biomass or other feedstock may be achieved through the use of
sealed reaction chambers according to various embodiments of this
invention. In one embodiment, this goal may be achieved through the
use of cartridges which may be sealed once assembled, and which may
be transferred between stations in a multi-station processing
system, while preserving the fluidic environment surrounding the
biomass during the transfer between processing stations. Also, a
piston-cylinder assembly may be utilized to provide the multiple
functions of pressure control, the intake of a working gas and the
extraction of fluids produced. Improved uniformity of biomass
processing may also be achieved through the introduction of a
mechanical agitator designed to mix the biomass during
processing.
[0015] Agitation can provide several benefits to the biomass
conversion process. When rapidly stirring a solid in a fluid
environment, the particles can be separated, exposing much higher
surface area levels of the biomass to the working fluid. In
addition, the relative motion of the fluid environment and the
biomass may create higher fluid flows over the biomass, again
helping to draw out volatile components. Agitation and mixing may
help to homogenize the mixture's temperature, which may be
important to ensuring that the volatile compounds produced are of a
consistent and usable composition. Additionally, the mixing action
itself may continue to break down and pulverize the biomass
materials, in particular breaking down the largest particles which
might otherwise not effectively volatilize compounds at their
core.
[0016] The combination of these rate-accelerating factors along
with removal of layer-thickness requirements enables a
substantially higher mass flow rate of solid biomass may be
processed, and a substantially higher mass flow rate of volatile
compounds may be produced from a given physical size of apparatus,
reducing the capital costs of equipment per unit of renewable fuel
that may be produced.
[0017] Various embodiments of the system described herein
effectively agitate and mix the biomass with a working fluid
contained in the sealed reaction chamber throughout a specified
temperature and pressure profile. The fluid contained in a sealed
reaction chamber may be liquid, gaseous, supercritical or
multi-phase. Such working fluids may include, for example, a
supercritical carbon dioxide rich and reduced oxygen fluid.
Alternatively, for processing other feedstocks, it may be practical
to utilize elements of the present invention in the processing of
solid feedstocks within a gaseous, liquid, or mixed phase fluid
environment.
[0018] In one embodiment, the sealed reaction chamber may be in the
form of a rotary drum cartridge, with biomass being tumbled
internally in a drum rotor. In another embodiment, the sealed
reaction chamber may be in the form of a cylindrical cartridge with
a mixer blade agitating the biomass. It will be apparent in view of
this disclosure that many other sealable cartridges of various
designs may be used in accordance with various embodiments of the
present invention.
[0019] In addition, it should be understood that while it may be
advantageous to utilize a sealed cartridge, which may contain both
biomass and a fluidic environment, in transferring biomass from one
station to another in a series of processing steps, there are
alternative embodiments where the reaction chamber is only sealed
during processing, and is opened or separated between processing
steps.
[0020] The seals in prior tray systems were maintained by flexible
bellows sealing to the top of the trays, which can be problematic
from the standpoint of mechanical reliability, particularly in an
environment with volatile organic chemicals circulating
supercritical fluids and high pressure differentials. The present
invention considers the use of piston assemblies for the dual
functions of controlling fluid intake and exhaust (in combination
with valves) and for providing a more robust and more cost
effective sealing mechanism.
[0021] In embodiments where a cartridge may be used to transfer
materials from station to station, the flow of fluid into the
cartridge may be controlled by valved ports, which may be fully
sealed during transfer between stations. The cartridge as a whole
may be indexed between processing stations in a sealed
configuration, eliminating a series of sealing and working fluid
control issues.
[0022] The present invention also provides a method for converting
biomass to renewable fuels, the method comprising: providing a
device containing a programmable number of processing stations, and
a series of catalysts; inserting biomass into a plurality of sealed
cartridges; injecting the cartridges with a working fluid; indexing
the sealed cartridges from station to station, wherein the stations
heat the contents of the cartridges to a desired temperature
profile, such that the biomass decomposes into volatile and
non-volatile components; selectively collecting groups of volatile
compounds as they are released; and subjecting the volatile
components to a series of catalysts to produce at least one
renewable fuel.
[0023] Also, a method for converting biomass to renewable fuels is
provided, the method comprising: providing a device containing a
programmable number of processing stations and a series of
catalysts; subjecting biomass within the stations to at least one
programmable starting temperature; incrementing an individual
processing station temperature by programmable increments wherein
the biomass is agitated at least one processing station to enhance
the production of a volatile and a non-volatile component; and
subjecting the volatile components generated in each station
through the series of catalysts to produce at least one renewable
fuel.
[0024] Further, the present invention includes a system for
converting biomass to renewable fuels, the method comprising: a
device containing a programmable number of processing stations, and
a series of catalysts; means for inserting biomass into a plurality
of sealed cartridges; means for injecting the cartridges with a
working fluid; means for indexing the sealed cartridges from
station to station; means for heating the contents of the
cartridges to a desired temperature profile, such that the biomass
decomposes into volatile and non-volatile components; means for
collecting groups of volatile compounds as they are released; and
means for subjecting the volatile components to a series of
catalysts to produce at least one renewable fuel.
[0025] The present invention also provides a system for the
conversion of biomass to combustible fuels, the system comprising:
a device containing a programmable number of processing stations
and a series of catalysts; means for subjecting biomass within the
stations to at least one programmable starting temperature; means
for agitating the biomass at individual processing stations; means
for incrementing an individual processing station temperature by
programmable increments to produce a volatile and a non-volatile
component; and means for subjecting the volatile components
generated in each station through the series of catalysts to
produce at least one renewable fuel.
[0026] The subject matter of this application may involve, in some
cases, interrelated products, alternative solutions to a particular
problem, and/or a plurality of different uses of a single system or
article.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIGS. 1A, 1B, 1C and 1D illustrate, respectively, a side
view of an embodiment of a drum rotor cartridge, a front view of
the same cartridge, a sectional view showing the view along axis 1C
and a sectional view showing the view along axis 1D.
[0028] FIG. 2 shows a drum rotor cartridge incorporating an
internal fan assembly.
[0029] FIG. 3A illustrates an embodiment of a processing station
for indexing a cartridge.
[0030] FIG. 3B illustrates another embodiment of a processing
station for indexing a cartridge.
[0031] FIG. 3C illustrates another embodiment of a processing
station for indexing a cartridge.
[0032] FIG. 3D illustrates yet another embodiment of a processing
station for indexing a cartridge.
[0033] FIG. 4 shows an embodiment of a cartridge, incorporating a
mixing cartridge.
[0034] FIG. 5A shows a cross-sectional side view of an embodiment
of a piston-cylinder-agitator assembly.
[0035] FIG. 5B shows a cross sectional view along axis 5B of FIG.
5A.
[0036] FIG. 5C shows a cross section view along axis 5C of FIG.
5A.
[0037] FIG. 6 illustrates processing steps at a particular work
station.
[0038] FIGS. 7A-7C provide the process steps for three different
embodiments of a method of fuel production.
DETAILED DESCRIPTION
[0039] Cartridge Embodiments
[0040] In one example embodiment, cartridges in accordance with
various embodiments of the present invention may be utilized in the
processing of solid biomass and the extraction of volatile
components from the biomass in a supercritical fluid environment.
There are a number of potential configurations for cartridges in
accordance with the principles of the present invention. FIGS.
1A-1D and 2 illustrate an exemplary drum rotor cartridge, and FIG.
4 illustrates an exemplary mixing cartridge, but it should be
understood that any number of cartridge configurations may be
practicable.
[0041] FIGS. 1A through 1D provide respectively, a side view, an
end view and two cross-sectional views of an embodiment of the
present invention. FIG. 1A provides a side view of a drum rotor
cartridge in accordance with an embodiment of the present
invention. The side view of FIG. 1A shows a drum rotor cartridge 1,
with various ports that may be useful during feedstock processing.
In some example embodiments, the composition of the working
fluid(s) can be, for example, supercritical carbon dioxide, water,
methane, methanol, other small hydrocarbons, their oxygenates, and
any mixture thereof (e.g. 60% CO.sub.2, 30% Water, and 10% Methane
and other organics) although any suitable gaseous, liquid,
supercritical, or multi-phase fluid may be used. Cartridges
suitable for use in such embodiments may include a fluid intake
port 4 (a) and a fluid off-take port 4 (b). However, in some
example embodiments fluid intake and off-take may occur through a
common port. In still other embodiments there may be a plurality of
intake and/or off-take ports. Again referencing the side view of
FIG. 1A, any number of additional ports 4 (c) may also be provided,
each of which may be used to insert or attach features for viewing
the interior of the cartridge or for the measurement of parameters
such as, for example, temperature, pressure, or fluid
composition.
[0042] As shown in FIG. 1C, taken along section line 1C, an example
drum rotor cartridge 1 may be sealed by utilizing a cover 5 and a
base plate 6. In the example configuration shown in FIG. 1C cover 5
can be threaded onto the base plate 6 by threads 7 and may thereby
complete an o-ring seal 8. It will be apparent in light of this
disclosure that, in lieu of a base plate-cover assembly, a
clamshell or one of many other mating component designs may be
formed to form a sealed cartridge, such as a cylinder with
separable top and bottom caps. It will further be apparent in light
of this disclosure that there are many alternative ways to close
and seal the cartridge assembly, including bolting, snap-locks, and
a variety of other mechanisms.
[0043] To provide additional stiffness and structural support for
the cover 5 during pressurized operation, some example embodiments
may include a boss 18, which may be affixed to the cover with
internal threads mating to a central shaft 9. The central shaft 9
may be permanently or removably mounted to the base plate 6. The
cover-central shaft-base plate assembly may be assembled such that
the boss 18 is threaded onto the central shaft 9 simultaneous to
the threading of the cover 5 to the base plate 6. However, in other
example embodiments a removable central shaft 9 may be threaded
into the boss 18 following assembly of the cover 5 and baseplate 6.
In various example embodiments, the boss 18 can also provide
lateral stability to the central shaft 9, about which, in some such
embodiments, the drum 10 rotates. It will be apparent in light of
this disclosure that there are a plurality of ways to reinforce the
cover internally or externally, or that no reinforcement may be
required. It will also be apparent that many various methods of
stabilizing a central shaft may be employed, including the
possibility of providing no stabilization to at least one end of
the central shaft.
[0044] As shown in FIG. 1D the drum 10 may be supported by one or
more bearings 17 and be driven by a rotor 15 mounted to the drum
10. In some examples a stator 16 may be mounted to the central
shaft 9. Electrical signals may be transmitted to the stator 16
and, in some such example embodiments, may be controlled via inputs
to a motor drive connector 2, and a rotational sensor (not shown).
Such sensors may be used for timing electrical signals to the
stator 16 in order to control the rotor 15. The rotary drum 10 may
be driven in a continuous motion, in a reversing motion, or in a
pulsed mode in either direction, as may be beneficial to providing
the desired level of agitation of the biomass. While internal
stator 16 and rotor 15 components have been shown for purposes of
illustration in FIG. 1D, it should be appreciated that rotation of
the drum 10 may be driven by any number of motors and/or
transmissions internally or externally connected to a cartridge. In
the case of the connection of an external motor to a cartridge, a
rotating shaft may pass into the cartridge to convey the rotary
motion, while preserving a seal between the contents of the
cartridge and the external environment.
[0045] Drums in accordance with example embodiments of the present
invention may also include various other electrical devices such
as, for example, a heater, measurement devices for determining drum
position over time, internal component temperatures, and other
suitable devices. As shown in the example embodiment illustrated by
FIGS. 1A and 1B all such electrical connections may be linked
through electrical component connector 3, although any other
suitable means of transferring electrical signals and/or making
electrical connections may also be used in accordance with various
embodiments of the present invention.
[0046] In accordance with an example drum rotor cartridge 1, as
shown in FIG. 1C a rotary drum 10 may be located inside cover 5.
Solid biomass 11 such as, for example, celluloses, hemicelluloses,
lignin, starches, and/or lipids may be contained in the rotary drum
10. In accordance with the example embodiment illustrated by FIGS.
1A-1D and FIG. 2, the inner and outer 32 circumferential surfaces
of the rotary drum 10 may be a thin sheet of metal, and the
sidewalls 30 and 31 may be a very fine wire mesh. The wire mesh
may, in some embodiments, allow fluids to enter and leave the
rotary drum 10 while retaining the biomass 11 inside of the
drum.
[0047] A motion of the drum 10 is shown by arrow 12, showing
clockwise rotation in FIG. 1C It will be apparent in light of this
disclosure, however, that rotation in any direction and about any
axis can be used in accordance with various embodiments of the
present invention. As the rotary drum 10 rotates, particles of the
biomass 14 can be agitated by internal ribs 13 in the rotary drum
10. Such agitation of the biomass 11 (or other feedstock) acts to
accelerate the production of volatile compounds from the
biomass.
[0048] Because tightly controlled temperatures within the cartridge
1 may be desirable in many embodiments, heating elements 19 or
other heat sources can be provided and may be mounted to the base
plate 6, the cover 5, the drum 10, or any other location suitable
for varying the temperature of the working fluid and biomass 11.
Internal temperature sensors (not shown) may be mounted to internal
components such as the, for example, base plate 6, central shaft 9,
cover 5, or drum 10 to measure fluid temperatures or component
temperatures. Fluid temperatures may also be measured, for example,
via ports 4 (c) or by a thermocouple or other probe inserted
through a port down into the drum cartridge assembly. In one
embodiment a heating element 19 may be operated in a closed-loop
fashion to maintain a set temperature, follow a desired temperature
profile over time, and/or follow a desired temperature profile in
response to changes in other measurements within the drum, such as
pressure readings or measurements of fluid composition.
[0049] FIG. 2 shows the addition of an internal fan, which may be
utilized within a cartridge of any particular design to promote
circulation of the working fluid, but here is illustrated in
combination with the drum cartridge assembly described above.
Additionally, it will become apparent in light of this disclosure
that any number of configurations may be used to generate forced
flow within a cartridge. Circulating the working fluid, as with the
agitation of the biomass, may then have a tendency to (1) increase
temperature uniformity within the cartridge and (2) promote the
production of volatile compounds by increasing the fluid flow rates
relative to the biomass that may be processed in the cartridge.
[0050] The fan assembly illustrated by FIG. 2 may, in some
embodiments, be used to drive the flow of working fluid inside the
cartridge 1 in a pattern shown by circulating arrows 21, 22 and 23.
In the example shown, fluid may be driven by a fan blade 24 or
blades through a first fine mesh screen side plate 30 of the drum
10, as shown by arrow 21. It should be noted that the view shown in
FIG. 2 is rotated 90 degrees, and the central shaft 9 may normally
be oriented horizontally such that the flow described by arrow 21
would also be substantially horizontal. In accordance with the
example embodiment of FIG. 2, flow may continue out the second fine
mesh screen side plate 31, positioned for example, opposite the
first fine mesh screen side plate 30 of the drum 10, as is
illustrated by arrow 22 and may then circulate outside the drum 10
around the sheet metal outer circumferential surface 32.
[0051] The flow, as is shown, for example, in FIG. 2, may be driven
by a fan blade 24 or blades, which may be mounted on an independent
rotor 25, driven by an independent stator 26, and supported by
independent bearings 27. It should be understood by one skilled in
the art that the fan's action could also be driven by the same
rotor/stator/bearing set as enables the rotation of the drum, or
any other suitable drive apparatus, but it may be desirable at
times to control the flow rate of the fluid and the turning of the
drum rotor independently, so an independent case is shown here.
[0052] As the flow circulates back to the fan blade 24 intake area,
it may be helpful in some embodiments to provide a flow guide ring
28, which can be mounted to the base plate 6, and has a tight
clearance to the drum 10 to prevent leakage between the flow guide
ring 28 and the drum 10. The flow guide ring 28 may be a thin sheet
metal cylinder and, in some embodiments, a portion of the flow
guide ring closest to the base plate 6 and furthest from the drum
10 may include perforations 29, which permit the flow of fluid
through the perforations as shown by arrow 23 while preventing
parallel flow over the fan blade 24 or blades.
[0053] As the working fluid enters the fan intake area, the fluid
may pass over a heating plate 19, adding heat to the working fluid.
To enhance heat transfer at the heating plate, the heating plate
may contain ribs or protrusions (not shown) that increase the
surface area of the plate and enhance heat transfer to the working
fluid contained in the cartridge. It will be apparent in light of
this disclosure that the flows as shown may be reversed to provide
impingement flows down onto the heating plate, assisting with heat
transfer at the heating plate, and that any number of other
circulation and heating strategies may be employed to provide for
effective circulation and mixing of the fluid with the biomass 11
or other feedstock materials.
[0054] A cartridge according to an example embodiment of the
present invention may be indexed through successive processing
stations, as illustrated by FIGS. 3A-3D. The cartridge may be
indexed from station to station around a circular arrangement of
stations 41, 42, and 43, or an elliptical arrangement of stations
44. An arrangement can be in any number of stations and/or shapes
such as, for example, four processing stations in a circle 41 (FIG.
3A), six processing stations in a circle 42 (FIG. 3B), eight
processing stations in a circle 43 (FIG. 3C), and/or 18 stations in
a racetrack configuration 44 (FIG. 3D). Through the use of a
cartridge, which can include a fluidic environment, conventional
bellows and airlocks used for maintaining particular environmental
conditions can be eliminated, thereby also eliminating all sealing,
pressure management, mechanical reliability, station transfer, and
other complications and difficulties associated therewith.
Specifically, a cartridge-based system fully seals the biomass in a
controlled environment throughout processing, including during
transfer between stations.
[0055] It will be apparent in view of this disclosure that the
fluidic environment may be pressurized, evacuated, or maintained at
atmospheric conditions. The pressure of the fluidic environment can
be, for example, in the range of 0-220 atmospheres (e.g. 45-80
atmospheres), but various embodiments may use any pressure suitable
for processing. It will be further apparent that temperature may be
set prior to transfer and maintained utilizing thermal insulation
or that heating may continue during transfer. Processing
temperatures often vary and may be, for example, in the range of
190-850.degree. K (e.g. 304-798.degree. K, 512-748.degree. K, or
598-698.degree. K) but may, in various embodiments, be any
temperature suitable for processing. It will also be apparent in
view of this disclosure that agitation may be utilized to mix the
contents of the cartridge before, during, and/or after transfer to
maintain a homogeneous mixture.
[0056] In the case, as illustrated by FIGS. 1A-D and 2, where a
cartridge is a drum cartridge, a quantity of biomass may be
dispensed into the rotary drum 10 by removing the cover 5 from the
base plate 6. For some embodiments, such dispensing of biomass can
be completed prior to indexing the drum cartridge 1 through the
system. With the cover 5 removed, a door (not shown) in the sheet
metal outer circumferential surface 32 of the drum 10 may be opened
to allow biomass to be inserted into the drum 10. It will be
apparent in view of this disclosure that a door may be present in
the fine mesh screen side plates 30 or 31, and further that any
number of alternative methods may also permit the dispensing of
biomass into the drum 10. Following insertion of the biomass, the
cover 5 may be reattached to the base plate 6 and the cartridge 1
thereby sealed. In cases where other cartridges may be utilized,
suitable ports for the insertion of biomass, for the removal of
residual carbonaceous material, and for the cleaning of cartridges
may be provided. Whereas the following paragraphs describe indexing
of materials through various processing steps utilizing a drum
cartridge, it will be apparent in light of this disclosure that
similar processes may be followed with other cartridge designs.
[0057] Once the cartridge has been loaded with biomass, the
cartridge may be introduced into the arrangement of successive
processing stations, beginning with the first station 45. In other
embodiments the insertion of biomass may rather be performed at the
first station. The cartridge may be successively indexed across a
series of processing stations such as, for example, those labeled
in FIG. 3D as 46, 47, 48, 49, 50 and 51, and with the last of the
18 stations in the example sequence of FIG. 3D being labeled
52.
[0058] At the first station 45, a cartridge in accordance with
FIGS. 1A-1D and 2 may be mated to fittings that connect to the
various connection points on the cartridge. Specifically, fluid
intake and off-take fittings may be connected to the fluid intake
4(a) and off-take 4(b) ports in the drum cartridge. Measurement
connections for temperature, pressure and working fluid composition
may be made via ports 4(c) that allow for physical insertion of
measurement devices, or by way of electrical connections, with the
physical probes internal to and integral within the drum cartridge.
In some example embodiments electrical connections for driving the
various motors that may exist within the drum 10 including, for
example, the drum and a fan motor, can also be made at this
time.
[0059] Further electrical connections may include, for example,
those required for supporting a resistive heating element and can
be made at the first station 45 or any subsequent station. It is
alternatively possible to heat the drum via a host of other heating
technologies, including, for example, heating via mechanical
agitation, plasma heating, microwave heating, and heating the drum
with a flow of heated working fluid through the fluid intake and
off-take ports, or passing heat into the drum via a heat exchanger
using a circulating fluid, such as heating oil. With any method of
heating described above, heating connections may be made as the
cartridge is moved to successive stations, utilizing a common
interface architecture, and the heating connections may be
electrical, fluidic or even mechanical, in the case of heating by
agitation.
[0060] As may be required for some example processing sequences,
the cartridge may be substantially purged of oxygen and any
existing fluid by flowing a relatively non-reactive fluid in
through the intake port 4(a) and out through the off-take port
4(b). The cartridge 1 may then be charged to a desired pressure
with a fluid known to be advantageous for processing. As an
example, in processing biomass for the production of liquid
renewable fuels a supercritical fluid with high levels of carbon
dioxide and low oxygen levels may be useful for the extraction of
volatile compounds.
[0061] At the first processing station, the drum may be rotated to
confirm appropriate feedback from the rotational sensors, and other
components may also be tested to confirm proper operation of the
heating elements, effective seals, and/or other appropriate
preparations for processing may be undertaken.
[0062] The first processing station may then index the drum
cartridge to a second processing station. Each successive station
may be configured so that the drum cartridge assembly automatically
connects with each successive station on a standardized interface,
minimizing connection time and facilitating automation of the
indexing process.
[0063] At the second processing station, the drum cartridge may be
heated to an initial temperature T_start. The heat may be ramped to
the desired T_start with the drum rotating, so as to effectively
mix the biomass and ensure uniform heating of the biomass. During
the heating ramp, a circulation fan may be run inside the drum
cartridge, to preserve temperature uniformity. At each processing
station, the exterior of the drum cartridge may be insulated, to
prevent temperature loss from that exterior interface.
[0064] During the ramp to the desired T_start, the pressure in the
drum cartridge may be controlled in a closed-loop fashion to follow
a prescribed profile by utilizing the pressure measurement inside
the drum cartridge or through one of the ports. The pressure within
the drum cartridge may therefore be modulated at this station and
in subsequent stations by introducing additional fluid via the
fluid intake port, or by exhausting fluid from the fluid off-take
port. This pressure and temperature modulation may be conducted on
a continuous basis during processing in response to pressure and
temperature readings, as well as measurements of working fluid
composition.
[0065] Once the drum cartridge has reached the appropriate
temperatures and pressures for optimized processing of biomass,
which may be, for example, in the range of 190-850.degree. K (e.g.
304-798.degree. K, 512-748.degree. K, or 598-698.degree. K) and
0-250 atmospheres (e.g. 45-80 atmospheres), but may, in various
embodiments, be any combination of temperature and pressure
suitable for processing, the drum rotor speed and fan speed may be
set to the desired rates for the production of volatile compounds
from the biomass, and held there for an appropriate dwell time, or
these rates may be continuously adjusted in response to feedback
from the temperature, pressure and fluid composition
measurements.
[0066] It may be desirable to utilize supercritical fluids in the
drum cartridge during processing. For example, supercritical fluids
may be helpful in assisting in processing by increasing the rates
of heat transfer relative to gaseous environments and also by
providing a substantial increase in chemical reaction rates, as
compared to liquid environments, due to their much higher rates of
diffusion. Appropriate mixtures of supercritical fluids vary and
often depend on the types of reactants used and the types of
reaction products desired at each processing step.
[0067] It may also be desirable to circulate fluids through the
drum cartridge during processing. For example, if a carbon dioxide
rich supercritical fluid were introduced via continuous flow into
the intake port, and the biomass produces volatile organic
compounds to be utilized by a downstream process to make renewable
fuels, a supercritical fluid enriched with volatile organic
compounds may be continuously removed from the off-take port during
processing. Then the volatile organic compounds in the off-take
flow may be utilized to make renewable fuels, with the carbon
dioxide rich supercritical fluid eventually circulating and
returned to the processing station via the intake port. By
circulating flow through the intake and off-take ports, it may be
possible to reduce the extent by which the fluid inside the drum
cartridge may become saturated in desired products, such as
volatile organic compounds, slowing their production.
[0068] When circulating fluids into an out of a cartridge
containing biomass or other solid matter, the solid particles may
tend to be drawn through the fluid intake and off-take ports. To
prevent this, filters may be included on the inside of the ports,
to separate out the solid matter. As the filters may periodically
become soiled, it may be advantageous to reverse the flow of the
fluid through the ports periodically to clean the filters.
[0069] The processing of a solid reactant, such as biomass, may be
halted at a particular station when it has progressed to a desired
point. This point may be determined by a fixed period of time, by a
desired rise in pressure, or when a specific quantity of products,
such as volatile compounds, may have been obtained.
[0070] In any case, once it is determined that it is time to
progress to the next station, the intake and off-take valves may be
closed. The drum may be allowed to continue to rotate for a period,
maintaining the homogeneity of the mixture in the cartridge. The
heating element may be utilized to maintain a holding temperature
and the intake or off-take valves may also be utilized to maintain
a holding pressure.
[0071] The full cartridge, containing biomass and the working fluid
may then be indexed to the next station. Because both the biomass
and the working fluid environment may be passed in a single
cartridge, there may be no requirement for airlocks, or the
re-establishment of seals, except for the internal seals within the
appropriate valves.
[0072] The next station could simply continue the processing of
biomass at a higher temperature with the same working fluid
composition, it could add or subtract fluid to alter the working
pressure and/or composition, or it may purge the contents of the
cartridge and introduce an entirely new fluid composition, as may
be appropriate to the subsequent processing step. In some
embodiments the temperature may be increased at each new station by
increments such as, for example, in the range of 0-200.degree. K
(e.g. 25-50.degree. K), although it will be apparent in view of
this disclosure that any station-to-station temperature increment
suitable for processing may be used.
[0073] In the case of the production of volatile compounds from
biomass in the production of renewable fuels, as the cartridge may
be indexed through a series of stations, the temperatures may be
increased, driving off additional volatile compounds of differing
compositions as the biomass progresses. During this process, the
biomass may go through multiple steps of decomposition and
progress, for example, from an initial state which may be of a
lipid rich biomass to an intermediate state of hemicellulose rich
biomass to a final state of lignin rich biomass. In one example, a
hemicellulose type may comprise C5 sugars such as fructose and
xylose, which then further decompose to yield compounds such as
furfurals and hydroxymethylfurfurals.
[0074] The tight temperature range at each station, which may be
improved by agitation of the biomass and/or the fluid, may
therefore allow specific volatile compounds to be collected at each
station, and also may allow specific intermediary products of
biomass decomposition to be collected and utilized in subsequent
processing stations.
[0075] After processing of the feedstock material (such as biomass)
is complete, the drum cartridge may be exhausted via the off-take
port, and then the cover may be removed. Remaining carbonaceous
materials may be poured out of the door in the drum rotor, and the
drum rotor and entire drum cartridge assembly may be cleaned for
re-introduction into processing of a subsequent batch of
materials.
[0076] FIG. 4 shows another embodiment of a cartridge in accordance
with the principles of the current invention, in this case, a
mixing cartridge 68. In this case, the mixing of the biomass is
driven not by a rotary drum, but by a rotating agitator blade 52.
It should be understood that while two specific examples of
agitation may be provided, a number of other means of agitation
could be provided, including circulatory agitation, vibratory and
heat driven agitation, and agitation by phase changing materials
flow (such as the boiling of a liquid).
[0077] As shown in FIG. 4, to seal the mixing cartridge 68, a cover
5 may be sealed to a base plate 6, through the use of a screw
thread 7 and a seal ring 8. The sealed mixing cartridge 68 may have
ports 4 (one shown) for intake and off-take, and may also utilize
such ports for measurement of temperature, pressure, gas
composition and other process variables. The mixing cartridge 68
may also have other electrical connections for the motor and other
internal electronics, which may be not shown in this figure, but
have been previously described in the context of the drum
cartridge.
[0078] As shown in this embodiment, the central shaft may be a
rotary shaft 51, which may be rigidly connected to at least one
mixer blade 52. It should be understood that there may be multiple
mixer blades at various clock positions or altitudes, which may be
rigidly attached to the rotary shaft. The rotary shaft may be
driven by a rotor 53, supported by bearings 54 and driven by a
stator 55.
[0079] Separating the motor assembly from the materials being
processed above it, there may be a lower separation plate 56, which
may be sealed at its interior and exterior by internal seal 57 and
exterior seal 58. This lower separation plate may be rigidly
attached to and supported from below by the stator 55 and a support
ring 59. The solid material being processed, such as biomass, may
sit on top of the lower separation plate and therefore be agitated
as the mixer blade 52 circulates.
[0080] Higher up on the rotary shaft 52, there may be an upper
separation plate 60, which has its own internal seal 61 and
external seal 62. This separation plate may be free to travel
vertically along the length of the cover, or there may be a lower
stop ring 63 present to prevent it from traveling down and
contacting the mixer blade or an upper stop ring 66 present to halt
its upward travel.
[0081] There may be a working fluid cavity 64 created in the sealed
volume between the upper separation plate 60 and the lower
separation plate 56. The solid materials being processed in the
cartridge, such as biomass and the fluid contained in the
cartridge, may react in this working fluid cavity to produce the
desired products at any station in the processing sequence.
[0082] There may be a separate upper pressurized cavity 65 above
the upper separation plate 60, with the pressure in the upper
pressurized cavity controlled by a pressurization port 67. The
upper pressurized cavity may have a different fluid contained in it
from the working fluid cavity, which may be liquid, gaseous,
supercritical or multi-phase, and may not be intended to play any
role in the reactions occurring in the working fluid cavity. It may
also have the same fluid present as in the working fluid cavity,
but may have a different pressure.
[0083] The upper separation plate may be free to travel vertically,
which may allow pressures to equalize across the upper separation
plate 60 through the movement of the upper separation plate 60.
Accordingly, by increasing the pressure in the upper pressurized
cavity 65 the upper separation plate 60 may be moved downward and
by decreasing the pressure in the upper pressurized cavity 65, the
upper separation plate 60 may be moved up. (It should be understood
that either of the pressurized cavities should be understood to
have the potential to be pressurized or to have a vacuum
drawn).
[0084] A potential benefit of the ability to move the upper
separation plate up and down is that the large majority of the
volume of the fluid in the working fluid cavity 64 may be expelled
by moving the upper separation plate 60 downward toward the lower
separation plate 56, with an off-take port 4 opened. An additional
benefit is that fluids may be drawn into the assembly by raising
the upper separation plate 60 while an intake port 4 is open to set
an initial environment for processing. Finally, the pressure of the
working fluid during processing may be controlled by controlling
the pressure in the upper pressurized cavity 65 via a separate
pressurization port 67.
[0085] As the mixer blade rotates, materials that have accumulated
at the bottom of the working fluid cavity 64 may be agitated and
mixed. The agitation of the materials by the mixer blade 52 may
break the materials into finer particle sizes, enhancing the
desired chemical reactions. The rotation of the mixer blade 52 may
also help to mix and circulate the working fluid in the working
fluid cavity 64, providing additional temperature uniformity and
homogenization of the mixture.
[0086] The motion of the upper separation plate 60 may be
controlled by fluid flow into and out of the pressurized cavity
above it, but it could also be controlled by a motor or other
actuation mechanism. In one embodiment, the upper separation plate
60 may be designed with internal recesses to match the shape of the
mixer blade, so that the upper separation plate 60 may be brought
down very close to the lower separation plate, with the mixer blade
nesting into a mating cavity in the upper separation plate 60. In
the absence of a lower stop ring 63, this would permit the upper
separation plate 60 to move down very close to the lower separation
plate 56, which may allow the apparatus to nearly fully exhaust the
working fluid.
[0087] While an upper separation plate is shown in this figure, it
should be understood that any number of configurations may be
utilized within the cartridge to displace the working fluid with a
secondary fluid, so that the working fluid may be expelled when a
valve is open, or to use a secondary fluid to control pressure. For
example, a balloon or bellows inside a working fluid cavity could
also be inflated via a secondary port to displace the working
fluid, and a variety of other configurations may be practicable,
which may employ the use of a second fluid and a moveable barrier
that seals or at least partially seals in place some sort of
movable barrier between the two fluids.
[0088] As with the drum cartridge 1, the mixing cartridge 68 or
other cartridges may be indexed between processing stations, with a
common interface of ports to facilitate the automation of indexing.
Several of the other features of the drum cartridge including the
action of the various ports may also be applicable in the case of a
mixing cartridge or other cartridge configurations, including the
potential use of an independently driven or blower to circulate the
working fluid, the use of common port interfaces, etc.
[0089] As with the drum cartridge 1, the mixing cartridge 68 may
employ heating elements to maintain a desired internal working
temperature. Additionally, as with the drum cartridge, flow
mechanisms may be established within the mixing cartridge 68 to
agitate or circulate the working fluid. In particular, in the
embodiment of a mixing cartridge 68, lower or upper mixer blades on
the rotating shaft may be of utility in circulating and mixing the
fluidic components of the working fluid cavity with the solid
components.
[0090] State-of-the-art methods of producing volatile compounds
from thin compressed layers of biomass do allow for somewhat
uniform heating of biomass and permits some volatile materials to
escape from the biomass. However, the top surface of such thin
layers continues to have a different thermal profile from the
bottom surface, and the materials on the bottom surface must
diffuse volatile compounds through the packed material, as opposed
to the surface materials, which may evolve volatile materials
directly into the surrounding working fluid environment. To enhance
thermal conductivity and gain even moderate thermal uniformity,
this thin layer is often compressed, but such compression works
against the desired diffusion effects. Thus compressing the biomass
into a thin layer increases particle size, reduces surface area,
and reduces diffusion while failing to achieve ideal temperature
uniformity.
[0091] According to the present invention, solid materials such as
biomass may be processed in an uncompressed state with smaller
effective particle size and improved temperature uniformity.
Because the solid feedstock is processed as finer particles, in an
uncompressed state, there is more surface area available to the
fluid reactants, and the lack of compaction improves diffusion
rates.
[0092] The agitation and mixing of the biomass according to the
present invention has several additional benefits. The mixing of
the biomass itself ensures greater uniformity of temperature across
the biomass materials, which in turn, allows a greater volume of
biomass to be processed at a given time, increasing production
rates and decreasing capital costs per unit of renewable fuels
output. The mixing may also act to disperse the biomass into
smaller particles, increasing the surface area of biomass in
contact with the working fluid. Finally, through the cascading
effects of the repeated collisions in mixing, some of the larger
particles may tend to break down into smaller particles, further
increasing surface area and production rates.
[0093] The enhanced mixing of the biomass with the working fluid
may accelerate the evolution of volatile compounds. Additionally,
the flow of the fluid relative to the biomass accelerates
volatilization of the compounds. This may be particularly true if
there is the addition of an internal fan to circulate the working
fluid, as shown in FIG. 2. In addition to the mixing of the biomass
providing more consistent composition and temperature uniformity of
the solid feedstock, such as biomass, the mixing of the fluid
provides more consistent fluid composition and temperature as well.
Of particular note is the minimization of boundary layer effects at
the fluid interface to the solid material, which may form in a
stable layer over a flat plate of biomass in a tray, but would be
of much less significant of an effect in an agitated cartridge
apparatus, as is described by this invention, particularly with
agitated solid particles and/or additional forced working fluid
circulation.
[0094] The motion of any agitation mechanism may heat the mixture
to some extent through frictional effects. If this is desirable and
sufficient, it may be the only form of heating used in the process,
with temperatures controlled by the mechanical energy imparted via
measured rotational motion. If the heat provided is excessive, a
slower or pulsing motion of the agitation mechanism may be
appropriate to provide mixing, with less of a heating effect.
[0095] The duration of the mixing process may be controlled via any
one of a number of parameters. At the simplest level, it may be
controlled via a pre-established count of rotations, or by mixing
for a fixed period of time. It may also be controlled by monitoring
the working fluid trapped in the drum cartridge, measuring
temperatures, pressure changes or even changes in the chemistry of
the working fluid that may indicate that it is time to progress to
the next working station.
[0096] The processing of specific biomass mixtures may also benefit
from dwell periods for reactions to progress or for volatile
compounds to evolve from a solid substrate, such as volatile
compounds being produced by biomass during heating. During these
dwell periods, temperature, pressure and temperature may be
stabilized, or may follow a prescribed protocol. In the case of
agitation, agitation may be halted or continued during these dwell
periods, as may be the circulation of working fluid, if controlled
independently.
[0097] The cartridges described herein are example systems that may
be used to achieve the benefit of providing a sealed cartridge
containing both a solid material being processed and a local
working fluid environment. As will be apparent in light of this
disclosure, any sealed vessel or cartridge capable of containing
both a solid material and a working fluid is suitable for use with
an embodiment of the present invention and could be operated
utilizing similar principles. In particular, a sealed cartridge
could also be provided where there is no internal mixing device,
but nonetheless permits a working fluid to be passed station to
station in conjunction with a solid reactant such as biomass.
[0098] Another benefit of the present invention is to provide for
agitation of the solid feedstock or reactant. The solid feedstock
or reactant, such as biomass, may be agitated by a variety of
means. FIGS. 1A-D show a rotary drum apparatus suitable for
agitation, and FIG. 4 shows a mixer blade apparatus. However, as
will be apparent in light of this disclosure, agitation could also
be performed by any other means. For example, agitation could be
performed inside the cartridge using an internal motor driven by
electrical signals from the outside, by a motor with a stator and
rotor pair spanning a sealed gap, or an external motor attached to
a rotary shaft which penetrates the cartridge. Further examples of
agitation include agitating the cartridge itself externally, via
rotary motion, oscillatory motion, vibratory motion, or some
combination of these effects, potentially also including an
internal mixing device such as internal ribs or ball bearings for
driving internal movements and mixing of the internal working fluid
and/or solid contents as the cartridge may be moved from the
outside. Any other suitable agitation means are also
acceptable.
[0099] In addition to agitating the biomass, it may be advantageous
to concurrently agitate or circulate the working fluid included in
the cartridge. The present invention allows for agitation and/or
circulation of the working fluid. The fan shown in FIG. 2 is one
example method of doing so, and many others will be apparent in
light of this disclosure. Specifically, for example, flow may also
be established by circulating flow through the intake and off-take
valves. In alternative examples, flow or agitation of the working
fluid could be a result of the agitation and circulation of the
solid feedstock itself, as may occur naturally in a mixing
cartridge as shown in FIG. 4 or in other embodiments where the
biomass is agitated, or as a function of a heating process.
[0100] Another aim of the invention is to provide controlled heat
to the mixture being processed. Heat may be provided by conduction
from resistive heating elements in the base plate (as shown in
FIGS. 1A-D and 2), or by various other means. For example, heat may
be provided by microwave or infrared energy, by the addition of
heated working fluids, through the use of a plasma, by introduction
of heat with the working fluid via the intake port, by warming the
exterior of the cartridge, or by various other methods.
[0101] Yet another goal of the present invention is to provide
controlled pressure to the biomass and working fluid. The pressure
on the working fluid may be controlled by flowing fluid into or out
of the intake or off-take ports respectively, as may be
appropriate, or by controlling temperatures and fluid compositions,
which may also have an impact on working pressure. Additionally,
the control of pressure may be accomplished by having a movable
element which separates the working fluid in the container from a
second fluid, which may be utilized to control the pressure on the
opposite side of the movable member.
[0102] Further, the invention provides ports for the intake and/or
off-take of working fluid. The intake and off-take and ports may be
attached to a base plate or to a cover, and may be actuated by
electrical or mechanical means from outside of the cylinder. There
may be one port that is used both for intake and off-take, or there
may be multiple ports used for different purposes.
[0103] Another aim of the invention is to provide ports for the
measurement of process parameters. Process parameters such as
temperature, pressure and fluid composition may be measured by
various means. Internal sensors may be mounted within the
cartridge, with electrical signals being passed outside of the
cartridge via electrical connections. Alternatively, fluid
temperatures, pressures and compositions may be obtained by flowing
fluid into our out of the cartridge, or by inserting probes into
the cartridge to measure those parameters. Finally, optical sensing
through a lens in the cartridge may be a practicable way to
determine certain parameters.
[0104] A goal of the present invention is to allow solid feedstock
or reactants to be added to the cartridge and/or to clean the
cartridge. FIGS. 1A-D show a separable cover and base plate, which
thereby permit removing the cover to enable the addition of biomass
and the cleaning of the cartridge. There may be a number of ways to
accomplish this function, which include having a separable assembly
with integral seals that permit the entire cartridge to be resealed
once reassembled. But the geometry of the cartridge could be
cylindrical, spherical, a rectangular prism or other geometries. In
some configurations it may even be possible to allow for a fill
and/or cleaning port which does not require full disassembly of the
cartridge.
[0105] Yet another goal of the present invention is to advance the
cartridge through successive processing stations. Advancement of
the cartridge may be achieved via a number of means. Most simply,
mechanical advancement of the cartridge to the next station using a
conveyor or rotary platform that indexes in fixed increments may
allow the trays to progress through a number of stations. The use
of cartridges according to the present invention can, in some
example embodiments, maintain the fluidic environment during the
transition from one station to the next while processing one batch
of solid materials. Among the many advantages of this
cartridge-type station design, each station may process
biomaterials at different temperatures, pressures and/or mixing
speeds. Such processing can be performed independently using
equipment with a common set of interfaces between each cartridges
and each station, reducing the costs of construction, operation and
maintenance.
[0106] The present invention also aims to allow working fluid in
the cartridge to be changed at specific points during processing.
The working fluid inside the cartridge may be changed over by
purging the cartridge. Alternatively, turnover of the working fluid
may be enhanced by forcing the working fluid out of the cartridge
through the use of a movable or expandable member, such as a
separation plate, which may separate the working fluid from a
second fluid inside the cartridge which may be used to displace the
working fluid, or to draw in a new mixture of working fluids.
[0107] Stationary Pressure Chamber Embodiments
[0108] FIGS. 5A-C illustrate a piston-cylinder-agitator assembly
for the purpose of fractionating biomass fuels. A disc tray 101 may
be used to hold a thin layer of biomass such as, for example,
celluloses, hemicelluloses, lignin, starches, and/or lipids on its
top surface, containing the biomass inside a raised perimeter rim.
When processing the biomass, the disc tray 101 may be brought into
contact with a cylinder 102 with a seal 103 at the junction of the
cylinder and disk. This may be accomplished by raising the disc
tray 101 into contact with the cylinder 102, or lowering the
cylinder 102 into contact with the disk tray 101, thereby
compressing the seal 103. A piston 104 may be used with outer seals
105 to the cylinder and inner seals 106 to the agitation element
111 to contain the working fluid in the working fluid cavity 107
created between the piston 104, cylinder 102 and disk tray 101. The
seals may be of a compressed, deformable nature (such as an O-ring)
or of a rigid sliding nature (such as composite polymer engine
rings), depending on the speed of actuation of the piston, the
operating temperatures and pressures and the level of sealing
required, and where one seal is shown in several interfaces,
multiple seals may be employed.
[0109] The working fluid may be injected or extracted via ports 108
(only one shown) that may be opened or closed by associated valves
109. In some example embodiments the composition of the working
fluid(s) can be, for example, supercritical carbon dioxide, water,
methane, methanol, other small hydrocarbons, their oxygenates, and
any mixture thereof (e.g. 60% CO.sub.2, 30% Water, and 10% Methane
and other organics), although any suitable gaseous, liquid,
supercritical, or multi-phase fluid may be used. As the piston may
be actuated to move up or down, the working pressure in the working
fluid cavity 107 may be increased or decreased in a controlled
manner with the valves 109 closed. In some example cases the
pressure can be, for example, in the range of 0-220 atmospheres
(e.g. 45-80 atmospheres), but various embodiments may use any
pressure suitable for processing. For instance, the piston may
decrease the volume of the cylinder by greater than or equal to
50%, 75%, 90%, 95%, 98%, 99%, or 99.5%. When an intake valve may be
opened, retraction of the piston 104 may be utilized to draw a
prescribed working fluid into the working fluid cavity 107.
Similarly, when an outlet valve may be opened and an inlet valve
closed, the downward movement of the piston 104 into the working
fluid cavity 107 may be used to expel the fluid contents of the
working fluid cavity. While only one port and one valve is shown,
it will be apparent in light of this disclosure that multiple ports
or multiple valves on a single port may allow for the effective
channel of inlet and outlet fluid flows, or that the port may be
positioned at different locations in the cylinder, or even in the
disc tray or piston. With all ports closed, and during a heating
process in which volatiles are extracted, the cylinder may be
retracted in a controlled manner to maintain pressures or to follow
a prescribed pressure profile optimized for that processing step
(e.g. pressure variations within the range of 0-220
atmospheres).
[0110] The agitator drive shaft 111 may be actuated in two
directions by actuators (not shown). The agitator may be moved up
and down as shown by the arrows 112 and also may be rotated about
its axis as shown by the arrow 113. To the bottom of the agitator
drive shaft 111 are attached one or more mixer blades 114, with two
shown at 180 degrees in this embodiment, though it will be apparent
that any number of mixer blades may be appropriate.
[0111] In the illustrated embodiment, the agitator shaft has an
alignment conical chamfer 116, which allows the agitator drive
shaft to ride in a raised cone or boss 117 in the disc tray 101.
This has the advantage of stabilizing the agitator drive shaft as
the mixer blades come into contact with biomass as the agitator
drive shaft 111 may be rotating, causing the mixer blades 114 to
mix the biomass with the working fluid in the working fluid cavity
107. It has the secondary advantage of wiping biomass particles off
of the central axis of the disk tray, where they may experience
less homogeneous mixing than in the area where the mixer blades are
rotating. It should also be understood that the raised cone or boss
on the disc tray 117 may also be allowed to rotate with the
agitator shaft 111 through the use of a bearing allowing it to
rotate relative to the disk tray 101 or a rotary element sealed to
and penetrating the disk tray.
[0112] If a mixing process is utilized, when the mixing process is
complete, it may be advantageous to raise the agitator shaft 111
above the disk but below the piston, to allow it to rotate freely
in the working fluid cavity 107, which allows for any biomass
remaining on the mixer blade to be cleaned off of the mixer blade
and to drop back down into the disk tray 101. It may be helpful to
spin the mixer blade at high speeds, to reverse the motion of the
mixer blade rapidly, or even to tap the mixer blade against the
piston to facilitate shaking loose biomass which may have
adhered.
[0113] It may also be the case that biomass materials adhere to the
walls of the cylinder during processing. In this case, the mixer
blades 114 may be designed with a close tolerance to the cylinder
102, so that the rotary action of the mixer blades acts to clean
the sidewall of the cylinder. It may also be helpful if the piston
104 has a tight clearance to the cylinder 102, with an angled
approach of the piston rim to the cylinder wall such that the
outermost diametrical points of the piston come into contact with
biomass adhering to the wall and act as a knife scraper on the
sidewall of the cylinder, scraping materials back into the interior
of the cylinder.
[0114] At certain times during the processing of a biomass sample,
and in particular after mixing or prior to heating the biomass, it
may be advantageous to level the biomass in the disk tray. In other
words, at the end of the mixing process, the biomass may be
distributed unevenly, or toward the outer edge of the disk tray.
For uniform heating or subsequent processing, it may be helpful to
reestablish a thin level layer of biomass on the disk tray. This
may be achieved by lifting the mixer blades 114 so that the bottom
of the mixer blades are above the expected level of the flattened
biomass, and utilizing a rotary or oscillatory mixer blade to level
the biomass. It may also be helpful to withdraw the mixer blade to
nest up into the piston, so that the piston may be brought down to
press down the biomass, further leveling it. It should be readily
understood by one skilled in the art that any number of leveling
iterations of using the agitator to level the biomass and pressing
down with the piston may have utility in leveling the biomass. It
should also be understood that the application of pressure by the
piston during heating may facilitate the heating process by
enhancing conduction.
[0115] When mixing of the biomass may not be required for a
specific processing step, it may be advantageous in some
embodiments of this invention to withdraw the mixer blade upward
into a mating groove 15 in the piston 4 as shown in FIG. 5A. The
presence of this mating groove 15 in the piston 4 also allows the
piston bottom surface to come down very nearly to the top of the
disk tray 1. This may allow the working fluid cavity to be driven
to a de minimis volume, which in turn may allow for the expulsion
the substantial majority of the working fluid if the exhaust valve
were opened. It may also allow for the effective intake of a new
working fluid by raising the piston with an intake valve opened.
Alternatively, the piston may be utilized for the generation of
higher pressures by moving the piston downward while the valves are
closed. To accomplish the nesting of the mixer blade, the mixer
blade may be timed to the piston in terms of its angular position
via rotation of the mixer blade and/or rotation of the piston
itself.
[0116] Underneath the disk tray 103, a heating element may be
embedded in the base plate 118, allowing that heat may be produced
and transmitted through the disk tray 103 to the biomass and
working fluid enclosed in the working fluid cavity 107. Processing
temperatures often vary and may be, for example, in the range of
190-850.degree. K (e.g. 304-798.degree. K, 512-748.degree. K, or
598-698.degree. K), but may, in various embodiments, be any
temperature suitable for processing. The disk tray may then be
indexed to move through successive processing stations (not shown),
where the heat and pressure at each station may be carefully
controlled in processing. In some embodiments the temperature may
be increased at each new station by increments such as, for
example, in the range of 0-200.degree. K (e.g. 25-50 K), although
it will be apparent in view of this disclosure that any
station-to-station temperature increment suitable for processing
may be used. In addition, through the systems and methods described
herein, the intake of working fluid, the agitation of materials
during processing and the exhaustion of working fluid at each
station may be carefully controlled.
[0117] FIG. 5B shows a downward oriented view of the mixer blades
114 being driven by the agitator drive shaft 111. The mixer blades
are resting on or near the base of the disc tray 101, above which
the working fluid may be contained in the working fluid cavity 107.
By rotating the mixer blade 114 using the agitator drive shaft 111,
the biomass in the base of the disk tray 103 may be agitated. The
biomass and working fluid are contained by the cylinder 102 and
above by the piston seals (not shown in this section). Working
fluid may be allowed to enter or leave the working fluid cavity 107
by means of one or more valves 109 controlling flow through one or
more ports 108. As is shown in the section view of the mixer blade
in FIG. 1D, the mixer blades may be chamfered to contact the base
of the disk tray around the perimeter of the disk, while being
tapered back to prevent the mixer blades from blocking flow into
the intake or exhaust ports. Because it might be natural for the
biomass to be thrown into intake or exhaust ports by the mixer,
geometric traps and or screen filters may be included in the ports'
design, and it may be advantageous to reverse flow at times in the
ports to ensure that ports do not become clogged by biomass.
[0118] FIG. 5C shows a section view looking upward at the piston
104 from the working fluid cavity 107. In some embodiments, as
illustrated, the bottom of the piston 104 may contain a groove 115
(which could also be a series of grooves, depending on the nature
and orientation of the mixer blades 114) which may allow the mixer
blade to slip up into the piston when it is not in use. In order to
assure that a maximum quantity of biomass may be returned to the
transfer disk after processing for a stated period in this station,
the mixer blades 114 may be elevated above the disk tray 101 but
below the piston 104 so that any biomass on the mixer blades 114
may be dispelled and drops to the transfer disk. Then the mixer
blades 114 may be retracted using the agitator shaft 111 and
aligned with the groove 115. Subsequently, the piston may be moved
downward with an exhaust valve open, in order to exhaust the
volatile compounds produced during the heating and mixing
process.
[0119] FIG. 6 shows an overview of processing steps at a particular
work station, and FIGS. 7A-7C show the detailed process steps in
three exemplary implementations. In particular, FIG. 7A shows one
potential sequence for the movements of the piston and agitator,
the action of seals and valves, the application of heat, the
progression of the fluid contents of the cylinder and several
control considerations during processing.
[0120] The sequence shown is but one example, and it will be
apparent in light of this disclosure that not all steps are
included in all embodiments. It will be further apparent that any
number of variations may be preferred to optimize a particular
processing step. As an example, the application of heat could be
provided via the disk plate prior to stirring, as is described
here, or it could be provided in the cylinder itself during mixing
by a variety of means, including the introduction of hot working
fluids, plasma energy, microwave energy, or even to some extent by
the action of the agitator itself. Multiple heating, stirring and
dwelling sequences could occur in a single processing chamber, in
coordination with the application of planned temperature and
pressure profiles.
[0121] The disk tray may be first indexed to a workstation, where
it may be coupled to a cylinder and sealed against that cylinder.
Indexing between stations can be accomplished along a circular or
elliptical racetrack or other suitable design. Prior to sealing
against the cylinder, the disk tray may be exposed to the ambient
environment or a specified environment may be maintained over the
disk tray through the use of sliding seals and airlocks. If it is
exposed to an ambient equipment environment, that environment may
be maintained by external seals around the entire operating
mechanism of multiple cylinders and processing stations, to prevent
volatiles from reaching the exterior atmosphere, and also to
provide a controlled working fluid for production.
[0122] In this example, the disk tray may then be lifted up against
a seal on the bottom of the cylinder, to create a sealed volume
between the disk tray, the cylinder and the piston. It will be
apparent in view of this disclosure that sealing could be
accomplished by several methods, including, for example,
circumferential seals, face seals, or some combination thereof, and
that the orientation of disk tray and cylinder are somewhat
arbitrary in that the tray could be lifted up to the cylinder, the
cylinder could be lowered, or the disk and cylinder could be
oriented other than vertically and simply brought together to form
a seal.
[0123] As the tray may be lifted into place and a seal may be
formed with the cylinder, the biomass in the tray may come into
contact with the piston, which was resting near the bottom of its
travel, but which may be permitted to move up freely as the rising
tray lifts the biomass to contact the piston. This may ensure that
there is a minimum volume of equipment ambient fluid trapped above
the biomass as the cylinder seal may be formed.
[0124] Next a valve may be opened allowing a controlled working
fluid mixture to enter the chamber while the piston rises. It
should be understood that differing working fluids may be employed
at different processing stations, and at different stages of
processing within a given station, and that the operating
temperatures and pressures of the working fluids may be varied as
well. For example, if it is desired to drive the volatilization of
specific compounds from a mixture in a narrow band of temperature,
it may be helpful to utilize a working fluid mixture that retards
the evolution of those compounds until the biomass is thoroughly
mixed and the desired temperature has been reached. Then it may be
advantageous to change over the working fluid composition to a
working fluid composition designed to effectively draw off those
volatile compounds, or to speed the biomass decomposition that
gives rise to them.
[0125] For the purpose of clarity, in this example, the working
fluids, some examples of which are described herein, which are
intended to discourage the evolution of volatiles are referred to
as "non-reactive" in FIGS. 7A-7C, while the fluids intended to
promote the evolution of volatile compounds are referred to as
Fractionation Intake Fluids (or after volatile organic products
have been produced, are referred to as Fract. Intake+Fract.
Products) in FIGS. 7A-7C. It should be understood that there may be
some reactions that occur when "non-reactive" fluids are utilized,
but the distinction is between fluids designed to accelerate or
retard reactions or diffusion during processing.
[0126] In some example embodiments the composition of the fluid
mixture can be, for example, supercritical carbon dioxide, water,
methane, methanol, other small hydrocarbons, their oxygenates, and
any mixture thereof (e.g. 60% CO.sub.2, 30% Water, and 10% Methane
and other organics), although any suitable gaseous, liquid,
supercritical, or multi-phase fluid may be used. The next
processing step may involve stirring and leveling the biomass,
prior to further heating of the biomass, and it may not be
desirable to drive volatilize compounds until that process is
completed and the biomass is uniformly mixed and warmed. So the
working fluid environment for mixing and stirring may be different
in fluid composition and may differ in pressure and temperature
from the working fluid subsequently used to fractionate the biomass
and create the volatile products of the fractionation process.
[0127] After raising the piston above the biomass, the mixer blade,
which had previously been nested in the piston, may be lowered so
that it may freely rotate in the gap between the piston and
biomass. For example, if there is 1/8 inch of biomass on the tray,
the piston is raised 1 inch above the tray and there is a 7/8 inch
gap, a mixer blade of 3/8 inch thickness could freely rotate
unobstructed in the gap between the biomass and the piston with 1/4
inch of clearance above and below.
[0128] The mixer blade may then be lowered into the biomass to stir
the biomass, and it may be advantageous to lower the blade while it
also may be rotating. The blade may be lowered so that it touches
the bottom of the tray, and a scraping blade may be present on the
bottom of the mixer blade to help remove biomass that may be
adhering to the disk tray.
[0129] After a specified period of mixing, the mixer blade may be
raised to approximately 1/8 of an inch above the tray, so that the
stirring motion acts to level the biomass into a flat plane below
the mixer blade. During this time, it may be advantageous to
reverse the direction of the mixer blade, so that, instead of a
scraping action, angled blades may have a smoothing action.
[0130] Subsequently, the mixer blade may be raised to clean the
mixer blade. Cleaning of the blade may be accomplished by high
velocity rotation, by sharp reversals in direction, and even by
raising to contact and impact against the piston while in motion,
shaking loose residual materials.
[0131] In addition, during this processing step, it may be
advantageous to utilize the mixer blade to clean the piston walls.
If the clearance between the mixer blade and cylinder walls is
small, the walls may be cleaned by rotating the mixer blade near
the wall, and slowly raising or lowering the mixer blade to clean
the wall. Once the substantial majority of material has been
cleaned from the mixer blade, it may return for one more leveling
pass and one more cleaning cycle, or it may return to its nested
position in the piston.
[0132] Now that the biomass material may be thoroughly mixed, the
next step in this illustrative example might be to compact the
biomass by tamping down on it with the piston. This may be an
iterative process, where the piston pushes down on the biomass,
raises up, and then pushes down again. As the piston may be moving
up and down, it may be advantageous that valves controlling the
flow of the non-reactive working fluid are timed to open and close
so that appropriately non-reactive mixtures at the appropriate
pressure and temperature are drawn in on the up-stroke, and any
volatiles produced are exhausted to an appropriate downstream
process on each down-stroke. Alternatively, the fluidic contents of
the piston may simply be compressed during this phase of
processing, along with the biomass itself.
[0133] In one example embodiment, a homogenous and compacted layer
of biomass on the disk tray may subsequently be heated, for
example, by conduction through heating the tray. This is only one
example method for heating the biomass, and many other heating
methods will be apparent in view of this disclosure. The timing of
the heating of the biomass can be varied as part of the cycle as
well. For example the biomass may be heated within the cylinder by
the introduction of a pre-heated fractionation working fluid during
a subsequent processing step, or may be heated by a plasma, by
microwave energy or by various other means that will be apparent in
view of this disclosure. Processing temperatures often vary and may
be, for example, in the range of 190-850.degree. K (e.g.
304-798.degree. K, 512-748.degree. K, or 598-698.degree. K), but
may, in various embodiments, be any temperature suitable for
processing. Though it is not prescribed in this illustrative
example, additional iterations of stirring, leveling and tamping
may be performed following heating, in combination with additional
iterations of heating, as may be appropriate to generate a
homogenous mixture at the desired temperature or temperatures.
During these various pressurizing and heating processes, the
biomass may go through multiple steps of decomposition and
progress, for example, from an initial state which may be of a
lipid rich biomass to an intermediate state of hemicellulose rich
biomass to a final state of lignin rich biomass. In one example, a
hemicellulose type of biomass may comprise C5 sugars such as
fructose and xylose, which then further decompose to yield
compounds such as furfurals and hydroxymethylfurfurals.
[0134] During the decomposition of the biomass in tightly
controlled windows of temperature, pressure and working gas
composition, specific targeted volatile compounds may be produced,
which then may be subsequently reacted in a catalyst chain to
produce renewable fuels, such as gasoline.
[0135] Following heating, a valve may be opened permitting the
entry of the desired starting working fluid for the evolution of
volatile compounds. This working fluid may be drawn into the
chamber by the upward motion of the piston with the intake valve
opened. In this example, the piston may be brought back, for
example, approximately 5 inches with the valve opened and a working
fluid can be thereby drawn into the piston. The working fluid may
be, for example, a high pressure supercritical fluid to provide a
reduced oxygen environment but working fluids will vary and most
typically will be determined by the reactants being used and the
desired volatile reaction products. Then, by lowering the piston
back down toward the disk plate with the intake and exhaust valves
closed, the pressure in the chamber may be further increased.
[0136] Through this mechanism, the movement of the piston may be
used to control the pressure which, in some example cases can be,
for example, in the range of 0-220 atmospheres (e.g. 45-80
atmospheres) or any other pressure suitable for processing, of the
working fluid mixture during this and subsequent steps. As the
biomass produces volatile compounds that would otherwise increase
the pressure in the chamber, the piston may be retracted to hold
pressure, or the piston's motion may be controlled to increase or
decrease pressure during subsequent processing steps as may be
optimal for the extraction of these volatile compounds.
[0137] With a homogenous, heated biomass mixture resting on the
baseplate and the desired working fluid above, the biomass may now
be agitated to maximize the production of volatile compounds.
Specifically, the mixer blades may be lowered from their nested
position in the piston, and the mixer blades rotated and lowered to
stir the biomass.
[0138] The mixing of the biomass with the working fluid may
accelerate the evolution of volatile compounds. This occurs because
the action of the mixer at the base of the cylinder acts to throw
biomass up above it into the working fluid cavity, dispersing the
biomass into smaller particles, and breaking the flat disk of
biomass into smaller fragments and particles. Additionally, the
rapid flow and mixing of the working fluid with the biomass
accelerates volatilization of the compounds. Because the larger
fragments of biomass may tend to stay preferentially toward the
bottom of the chamber, they are more often reduced in size, leading
to a more homogenous particle size.
[0139] The motion of the mixer may heat the biomass through
frictional effects. If this is desirable and sufficient, it may be
the only form of heating used in the process, with temperatures
controlled by the mechanical energy imparted via measured
rotational motion. If the heat provided by mixing is excessive, a
slower or pulsing motion of the agitator may be appropriate to
provide mixing, with less of a heating effect.
[0140] The duration of the mixing process may be controlled to any
one of a number of parameters. At the simplest level, it may be
controlled via a pre-established count of rotations, or by mixing
for a fixed period of time. It may also be controlled by monitoring
the working fluid trapped in the piston, measuring temperatures,
pressure changes or even changes in the chemistry of the working
fluid that may indicate that it may be time to progress to the next
working station. Finally, if pressure is being held constant by a
piston's movement, the motion of the piston to a particular point
may indicate that a certain volume of volatile compounds has been
produced, and it may be the optimal time to progress to the next
step in the process.
[0141] The processing of specific biomass mixtures may also benefit
from dwell periods for reaction and for the production and
diffusion of volatile compounds. During these dwell periods, the
agitation may be halted, and the mixer may first level the biomass
on the heating plate, and then may allow the biomass to sit as
volatile compounds are released. If additional heat input may be
desired, further compaction of the biomass may be accomplished by
pressing down the piston on the biomass, but if heating is
sufficient, it may be more efficacious to allow the volatile
compounds to be drawn off of the biomass in an uncompressed state
with improved fluid flow to the individual particles.
[0142] This next dwell step of the process may involve the
production of volatile compounds from a thin layer of compressed
biomass, during which the biomass may be subjected to a prescribed
temperature and pressure profile. However, there are advantages
possible from the availability of an agitator mechanism. The
materials may be cycled through multiple iterations of volatile
compound evolution when mixing and when in a leveled material
dwell. In addition, instead of the material in the top layer of the
disk tray remaining on the top layer for the duration of a
processing step, and across multiple processing steps, the
agitation mechanism allows for mixing of materials for more
homogenous volatilization of the organic compounds in the biomass
within each station, and then again at each subsequent station.
[0143] Following multiple potential iterations of agitation and
dwell periods (and with the understanding that cases of no
agitation or no dwell periods may be advantageous for processing in
certain conditions), during which the desired quantity of volatile
compounds may have been extracted from the biomass, the mixer blade
may be withdrawn to the working fluid cavity above the biomass and
cleaned as has been described above. Following cleaning of the
mixer blade, the biomass may be leveled, and the sequence of
cleaning and leveling may be iterated multiple times to achieve
both a level tray of biomass and a clean mixer blade, which may
then be nested back into the piston.
[0144] With the mixer blade nested in the piston, the outlet valve
for the working fluid may be opened as the piston may be moved
down, nearly completely exhausting the working fluid from the
piston-cylinder assembly. At this point, the biomass may also be
tamped down, to push out remaining fluid that may be trapped in the
biomass pile, and also to slow further reaction during passing the
tray to the subsequent processing step. The outlet valve for the
working fluid containing the volatilized compounds may then be
closed, sealing off the chamber, and finally the tray may be
dropped, allowing the disk tray to increment to the next
station.
[0145] The various elements described in the above embodiment
perform certain functions, but those functions may be achieved
through alternative means. Several beneficial functions and
alternative means of achieving them are described below.
[0146] The invention aims to provide a seal between the disc tray
and the cylinder. Such seals between the cylinder and the disk tray
may be a face seal (as shown in FIG. 5A), a radial seal or some
combination of multiple seals.
[0147] Another aim of the present invention is to provide ports for
the intake or exhaustion of working fluid. The intake, exhaust and
measurement ports may be included in the side of the cylinder (as
shown) or by using ports penetrating the cylinder, disk tray or
even the piston.
[0148] Further, the invention aims to provide controlled heat to
the biomass and working fluid. Heat may be provided by conduction
up through the disk tray (as shown), by heating elements in the
cylinder, by microwave or infrared energy, by the addition of
heated working fluids, through the use of a plasma, or by various
other methods that will be apparent in view of this disclosure.
[0149] The present invention also aims to provide controlled
pressure to the biomass and working fluid. The pressure on the
working fluid may be applied by a piston, or via one of the intake
or exhaust ports, as may be appropriate, or may also be used with a
movable internal element like a balloon or bladder, which separates
a pressurization fluid from a working fluid.
[0150] Another goal of the present invention is to measure key
parameters of biomass and working fluid. The measurement of heat
and temperature of the biomass during processing is not shown, but
is readily understood to be practicable by the insertion of a
temperature or pressure sensor in a port such as has been shown for
the intake and exhaust valves. Measurement of temperature or
pressure could also be addressed by measurements on the cylinder
wall or through the disk tray. Measurement of the composition of
the working fluid's chemistry may also be helpful, particularly in
assessing the progress in producing specific products.
[0151] Yet another aim of the invention is to provide a controlled
method to mix or agitate the biomass during processing. There are a
number of ways of accomplishing the mixing function. The mixing
function may be accomplished by an agitator driven mechanically
from the top by an agitator drive shaft coaxial with the piston.
The agitation may be driven from the bottom by a drive shaft
protruding through and sealed to the disk tray. The agitation could
be driven by a freely rotating element within the piston and
cylinder with magnetic properties that allow it to be driven by
magnetic fields surrounding the cylinder. Finally, the entire
assembly could potentially be shaken or rotated, therefore causing
agitation of the materials inside, particularly if there are ribs
or movable elements inside the apparatus.
[0152] Another aim of the present invention is to allow the chamber
and mixer to be cleaned prior to transfer of biomass to the next
station. The agitation method described herein may be
self-cleaning, to minimize any biomass residuals left in the
cylinder above the disk tray at the completion of a cycle, which
would otherwise be reintroduced into the next set of biomass
introduced at that station. Because presumably that material had
already given off a targeted range of volatile chemical compounds,
and may now be producing non-targeted compounds, materials that are
not fully expelled during a particular cycle have a potential to
contaminate the next cycle.
[0153] Another aim of the invention is to allow the disk tray to be
advanced through successive processing stations. Advancement of the
disk tray is not illustrated here, but may be achieved via any
suitable means. Most simply, mechanical advancement of the tray to
the next station using a conveyor or rotary platform that indexes
in fixed increments may allow the trays to progress through a
number of stations. One of the advantages of this type of station
design may be that each station can independently operate at
different operating temperatures, pressures and/or mixing speeds
while using a common piston-cylinder architecture, and a set of
common interchangeable components, reducing costs of construction,
operation and maintenance.
[0154] The present invention may also contain some beneficial
functions that have not been discussed. For example, actuation of
the piston and agitator shaft is not shown, but may be easily
accomplished through a variety of means, such as motors, drive
screws, cams, levers, crankshafts, linear motors, as may be
suitable for any specific embodiment. In one configuration, the top
of the piston-cylinder assembly may be fully sealed in order to
contain any fluids that may slip through the outer seals 5 or inner
seals 6, and the piston and agitator shaft are controlled by motors
inside the top of the sealed portion of the assembly that are
magnetically coupled to an external set of drive stators located
outside the sealed assembly. This has the benefit of providing a
full stationary secondary seal containing any volatiles
produced.
[0155] It should be understood that for certain process steps,
agitation of the biomass may not be desirable. Accordingly, the
piston-cylinder assembly may also be implemented without mixer
blades 114, an agitator shaft 111, or internal seals 106.
[0156] It should also be understood that for certain process steps,
control of pressure or the intake and exhaust of working fluid with
a piston may not be required. Accordingly, a system of agitation
may be employed in cases that do not require a piston.
[0157] It should be understood that there may be alternative ways
to displace the working gas from the working gas cavity than a
piston mechanism. An alternative may be a balloon or bellows
assembly in the cavity that can be filled from a separate external
port with a secondary fluid. This secondary fluid may then be
utilized to adjust the volume of the working cavity. Making these
adjustments in combination with the action of the intake and
exhaust valves, as previously described, may allow the cavity to be
substantially purged of its working fluid, to draw in a new batch
of working fluid, or to control the pressure on the working fluid,
as described previously.
[0158] While several embodiments of the present invention have been
described and illustrated herein, those of ordinary skill in the
art will readily envision a variety of other means and/or
structures for performing the functions and/or obtaining the
results and/or one or more of the advantages described herein, and
each of such variations and/or modifications is deemed to be within
the scope of the present invention. More generally, those skilled
in the art will readily appreciate that all parameters, dimensions,
materials, and configurations described herein are meant to be
exemplary and that the actual parameters, dimensions, materials,
and/or configurations will depend upon the specific application or
applications for which the teachings of the present invention
is/are used. Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, many
equivalents to the specific embodiments of the invention described
herein. It is, therefore, to be understood that the foregoing
embodiments are presented by way of example only and that, within
the scope of the appended claims and equivalents thereto, the
invention may be practiced otherwise than as specifically described
and claimed. The present invention is directed to each individual
feature, system, article, material, kit, and/or method described
herein. In addition, any combination of two or more such features,
systems, articles, materials, kits, and/or methods, if such
features, systems, articles, materials, kits, and/or methods are
not mutually inconsistent, is included within the scope of the
present invention.
[0159] All definitions, as defined and used herein, should be
understood to control over dictionary definitions, definitions in
documents incorporated by reference, and/or ordinary meanings of
the defined terms.
[0160] As used herein, the term `biomass` includes any material
derived or readily obtained from plant sources. Such material can
include without limitation: (i) plant products such as bark,
leaves, tree branches, tree stumps, hardwood chips, softwood chips,
grape pumice, sugarcane bagasse, switchgrass; and (ii) pellet
material such as grass, wood and hay pellets, crop products such as
corn, wheat and kenaf. This term may also include seeds such as
vegetable seeds, fruit seeds, and legume seeds.
[0161] The term `biomass` can also include: (i) waste products
including animal manure such as poultry derived waste; (ii)
commercial or recycled material including plastic, paper, paper
pulp, cardboard, sawdust, timber residue, wood shavings and cloth;
(iii) municipal waste including sewage waste; (iv) agricultural
waste such as coconut shells, pecan shells, almond shells, coffee
grounds; and (v) agricultural feed products such as rice straw,
wheat straw, rice hulls, corn stover, corn straw, and corn
cobs.
[0162] The indefinite articles "a" and "an," as used herein in the
specification and in the claims, unless clearly indicated to the
contrary, should be understood to mean "at least one."
[0163] The phrase "and/or," as used herein in the specification and
in the claims, should be understood to mean "either or both" of the
elements so conjoined, i.e., elements that are conjunctively
present in some cases and disjunctively present in other cases.
Other elements may optionally be present other than the elements
specifically identified by the "and/or" clause, whether related or
unrelated to those elements specifically identified, unless clearly
indicated to the contrary.
[0164] All references, patents and patent applications and
publications that are cited or referred to in this application are
incorporated in their entirety herein by reference.
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