U.S. patent application number 12/795989 was filed with the patent office on 2010-09-30 for systems and methods for reactor and receiver control of flux profile.
This patent application is currently assigned to SUNDROP FUELS, INC.. Invention is credited to Courtland Hilton, Joseph Hilton, Zoran Jovanovic, Donna Kelley, Andrew Minden, Christopher Perkins, Wayne Simmons, Steven Strand.
Application Number | 20100242352 12/795989 |
Document ID | / |
Family ID | 42736707 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100242352 |
Kind Code |
A1 |
Perkins; Christopher ; et
al. |
September 30, 2010 |
SYSTEMS AND METHODS FOR REACTOR AND RECEIVER CONTROL OF FLUX
PROFILE
Abstract
A method, apparatus, and system for a solar-driven chemical
reactor are disclosed, including a solar thermal receiver aligned
to absorb concentrated solar energy. Some embodiments include a
solar driven chemical reactor that has multiple reactor tubes. Some
embodiments include one of 1) one or more apertures open to an
atmosphere of the Earth or 2) one or more windows, to pass the
concentrated solar energy into the solar thermal receiver. This
energy impinges on the multiple reactor tubes and cavity walls of
the receiver and transfer energy by solar radiation absorption and
heat radiation, convection, and conduction. In this way, the energy
causes reacting particles to drive the endothermic chemical
reaction flowing in the reactor tubes. The design of the multiple
reactor tubes and solar thermal receiver can be adapted per a solar
flux profile to take advantage of variations in the concentrations
of solar flux in the profile.
Inventors: |
Perkins; Christopher;
(Boulder, CO) ; Hilton; Courtland; (Broomfield,
CO) ; Strand; Steven; (Midland, MI) ; Kelley;
Donna; (Louisville, CO) ; Simmons; Wayne;
(Dublin, OH) ; Minden; Andrew; (Boulder, CO)
; Hilton; Joseph; (Provo, UT) ; Jovanovic;
Zoran; (Louisville, CO) |
Correspondence
Address: |
Rutan & Tucker, LLP.
611 ANTON BLVD, SUITE 1400
COSTA MESA
CA
92626
US
|
Assignee: |
SUNDROP FUELS, INC.
Louisville
CO
|
Family ID: |
42736707 |
Appl. No.: |
12/795989 |
Filed: |
June 8, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61248282 |
Oct 2, 2009 |
|
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61185492 |
Jun 9, 2009 |
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Current U.S.
Class: |
44/639 ; 422/108;
422/186.3 |
Current CPC
Class: |
C01B 3/384 20130101;
C10J 2300/1223 20130101; C10L 1/04 20130101; Y02P 20/50 20151101;
C10G 3/00 20130101; C10G 2300/1014 20130101; C10G 2300/1025
20130101; C10J 2300/1861 20130101; C10L 2200/0492 20130101; C10J
3/482 20130101; C10L 2290/50 20130101; C10J 2300/1693 20130101;
C07C 29/1518 20130101; C10J 2300/123 20130101; C10J 3/485 20130101;
C10J 3/60 20130101; C10J 2300/0989 20130101; C10L 2290/52 20130101;
B01J 19/245 20130101; C10L 2290/28 20130101; C10L 2290/42 20130101;
C10J 3/721 20130101; B01J 2219/00186 20130101; C10J 3/56 20130101;
C10J 2300/0993 20130101; C10L 2290/547 20130101; Y02P 20/133
20151101; C01B 2203/0233 20130101; B01J 2219/00117 20130101; C10G
2/32 20130101; C01B 2203/1241 20130101; Y02T 50/678 20130101; C10L
2290/02 20130101; C01B 2203/0811 20130101; C01B 2203/84 20130101;
C07C 29/15 20130101; B01J 19/0033 20130101; C10J 2300/0973
20130101; C10J 2300/1284 20130101; C10J 2300/1665 20130101; Y02E
10/40 20130101; Y02E 50/30 20130101; C10J 3/58 20130101; C10J
2300/0909 20130101; C10L 2290/08 20130101; C01B 3/22 20130101; Y02E
50/10 20130101; C01B 2203/0216 20130101; C10J 2300/0976 20130101;
Y02P 20/145 20151101; C10J 2300/094 20130101; Y02B 40/18 20130101;
C10J 3/84 20130101; C10L 2290/04 20130101; C10J 2300/0906 20130101;
C10J 2300/1292 20130101; C10J 2300/0916 20130101; F24S 20/20
20180501; C01B 2203/1685 20130101; C10G 2/30 20130101; C10J 3/723
20130101; C10J 2300/1621 20130101; Y02P 20/129 20151101; C01B 3/34
20130101; C10J 3/466 20130101; Y02P 30/20 20151101; B01J 19/0013
20130101; C10J 3/506 20130101; C10J 2300/1659 20130101; C10J
2300/1853 20130101; C10K 1/024 20130101; B01J 19/2445 20130101;
C10G 2300/807 20130101; C10J 2200/15 20130101; C10J 3/00 20130101;
C10J 2200/09 20130101; C10J 3/82 20130101; C01B 2203/061 20130101;
C10J 3/54 20130101; C10J 3/62 20130101; C10J 2200/158 20130101;
C10L 2290/06 20130101; C07C 29/15 20130101; C07C 31/04 20130101;
C07C 29/1518 20130101; C07C 31/04 20130101 |
Class at
Publication: |
44/639 ;
422/186.3; 422/108 |
International
Class: |
C10L 1/02 20060101
C10L001/02; B01J 19/12 20060101 B01J019/12 |
Claims
1. A solar-driven chemical reactor system, comprising: a solar
thermal receiver aligned to absorb concentrated solar energy from
one or more solar energy concentrating fields including either 1)
an array of heliostats, 2) a solar concentrating dish, or 3) any
combination of the two; a solar driven chemical reactor that has
multiple reactor tubes located inside the solar thermal receiver,
where an endothermic chemical reaction driven principally by
radiant heat occurs in the multiple reactor tubes, where the
multiple reactor tubes in this reactor design increase available
reactor surface area for radiative exchange to the reactants as
well as creates an inter-tube radiation exchange, wherein the
endothermic chemical reaction includes one or more of the
following: biomass gasification, steam methane reforming, methane
cracking, steam ethane or naphtha cracking to produce ethylene and
related olefins, metals refining, carbon dioxide splitting, or
water splitting to be conducted in this chemical reactor using
solar thermal energy coming from the concentrated solar energy; and
one or more apertures in the receiver 1) open to an atmosphere of
the Earth or 2) with a transparent window covering the aperture, to
pass the concentrated solar energy into the solar thermal receiver
to impinge on the multiple reactor tubes and cavity walls of the
receiver and transfer energy by absorption, re-radiation,
convection, and conduction to the reactants in the chemical
reaction to drive the endothermic chemical reaction flowing in the
reactor tubes, wherein a design of the multiple reactor tubes and
solar thermal receiver are adapted per a solar flux profile to take
advantage of variations in concentrations of solar flux in the
solar flux profile including adapting two or more of 1) an amount
of the at least two or more reactor tubes present in the cavity of
the solar thermal receiver, 2) a size diameter of each of the
reactor tubes in which a first reactor tube may have a different
diameter than a second reactor tube, 3) a geometric arrangement of
the multiple reactor tubes relative to each other, 4) a shape of
each individual reactor tube may vary with respect to other tubes
per the flux profile to take advantage of variations in solar flux
in the profile and 5) a size, shape, and orientation of the
apertures relative to the concentrated solar energy coming from the
solar energy concentrating field.
2. The solar-driven chemical reactor system of claim 1, wherein the
endothermic chemical reaction is at least biomass gasification, and
where materials selected for the inner cavity wall and the reactor
tubes combined with an amount of concentrated solar energy from one
or more solar energy concentrating fields cause heat transfer from
the cavity walls and reactor tubes to transfer heat in a sufficient
amount to the particles of biomass flowing in the reactor tubes to
achieve the temperature necessary for substantial tar destruction
and gasification of greater than 90 percent of the biomass
particles into reaction products, including hydrogen and carbon
monoxide gas, in a very short residence time between a range of
0.01 and 5 seconds.
3. The solar-driven chemical reactor system of claim 2, further
comprising: a length and diameter dimensions of a gasification
reaction zone of each of the reactor tubes, along with an
arrangement and an amount of the tubes are matched to an amount of
solar energy from the heliostat field to give the fast residence
time of 0.01 second to 5 seconds, with the preferred residence time
of 2-3 seconds at the biomass gasification temperatures of greater
than 950 degree C., where the first of the multiple tubes that has
a different diameter than the second of the multiple tubes, has a
larger diameter, and is located in a higher solar flux
concentration and/or higher temperature zone in the cavity of the
receiver than the second tube, where the geometrical configuration
of the multiple reactor tubes in the receiver relative to each
other is in a linear pattern, semi circular pattern, arc pattern,
cylindrical pattern, rectangular pattern, or some other arbitrary
arrangement, wherein an inner diameter of the reactor tubes is
sized to allow a substantially uniform gasification of the biomass
particles from the edges to the center of the tube, and have a wall
thickness in a range of 1/8''-2'', that is set to withstand at
least a 75 psig pressure when the inside tube walls are at
1400.degree. C., and an on-site chemical synthesis reactor that is
geographically located on the same site as the chemical reactor and
has an input to receive the gasification products including
hydrogen and carbon monoxide for a hydrocarbon synthesis process
performed in the on-site chemical synthesis reactor to create
hydrocarbon fuels and/or chemicals.
4. The solar-driven chemical reactor system of claim 2, wherein a
shape of each reactor tube is a cylindrical shaped pipe, at least
30 reactor tubes are present in the cavity of the solar thermal
receiver, the geometric arrangement of the at least 30 reactor
tubes relative to each other is an arc pattern, and a shape of the
aperture is approximately a square, and wherein at least some the
products resulting from the chemical reaction in the solar driven
chemical reactor are supplied to an input of a downstream chemical
synthesis processes, in which methanol is generated and then
supplied to a Methanol-to-Gasoline process.
5. The solar-driven chemical reactor system of claim 2, further
comprising: two or more zones in the receiver in which the reactor
tubes in each zone are made out of different materials to adapt to
1) an amount of heat flux in that zone, 2) peak temperature of that
zone, and 3) corrosion conditions in that zone, a tower that
supports and elevates the solar thermal receiver and solar driven
chemical reactor, wherein the tower is at least tall enough, equal
to or greater than 100 meters, in height to give an optimized angle
of elevation for the one or more solar energy concentrating fields
to supply the concentrated solar energy to the solar thermal
receiver and solar driven chemical reactor while minimizing an
amount of heliostats or solar concentrating dishes and acreage of
land occupied by these heliostats or solar concentrating dishes
needed to deliver an amount of concentrated solar energy to the
apertures with a flux in the range of 750-3500 kW m.sup.-2, and
wherein the concentration of solar energy into the apertures
achieves the heat transfer rates at the inner wall of the cavity
and reactor tubes to allow the particles of biomass to achieve the
temperatures necessary for substantial tar mitigation to less than
50 mg/m 3 and to gasification of greater than 90 percent of the
biomass particles into reactant products.
6. The solar-driven chemical reactor system of claim 2, wherein a
first solar energy concentrating field is an arrangement of
heliostats in rows of differing spacing such that as the distance
of each row of heliostats from the receiver is increased, then the
height of the heliostats in that row is increased and also the
spacing between heliostat rows is increased, and where the
non-uniform heliostat field is used to generate an average
concentration of solar energy at the aperture of the receiver
greater than or equal to 500 times the direct normal insulation
concurrently incident upon the solar energy concentrating
field.
7. The solar-driven chemical reactor system of claim 6, wherein the
heliostat field has >25,000 m.sup.2 of reflecting surface that
cooperates with the solar thermal receiver to control an amount of
solar energy into the apertures and onto the reactor tubes and
cavity walls thereby maintaining the temperature required for
gasification of greater than 90 percent of the biomass particles
into the reactant products that include the hydrogen and carbon
monoxide gas in a residence time between the range of 0.01 and 5
seconds, and where the size and a shape of each of the one or more
apertures of the receiver is determined by the balance between the
power in the portion of the focus of the heliostat field accepted
into the aperture and the total amount of energy that is needed to
achieve the residence times.
8. The solar-driven chemical reactor system of claim 6, wherein the
heliostat field has >100,000 m.sup.2 of reflecting surface that
cooperates with the solar thermal receiver to have an ability to
control an amount of solar energy flux across the apertures that is
applied to reactor tubes and cavity walls to allow enough energy
from a radiant energy to raise the heat inside the tubes to
initiate and sustain a sufficiently high temperature so that the
gasification occurs of greater than 90 percent of the biomass
particles into the reactant products that include the hydrogen and
carbon monoxide gas in a residence time between the range of 0.01
and 2 seconds, and wherein the solar energy concentrating field
generates an average concentration of solar energy at the aperture
of the receiver greater than or equal to 1000 times the direct
normal insulation concurrently incident upon the solar energy
concentrating field.
9. The solar-driven chemical reactor system of claim 1, further
comprising: baffles positioned at select locations within the
cavity of receiver and combined with an intertube radiation
exchange between the multiple reactor tube geometric arrangement
relative to each other is used to shape a distribution of incident
radiation via reflection or absorption within the receiver cavity,
wherein the concentrated solar energy field is a heliostat field
and the concentrated solar energy from the heliostat field is in an
amount of concentration of suns sufficient to produce equal to or
greater than 750 kW per meters squared of solar energy at the
apertures, which gives the receiver cavity to have a capacity of at
least 2000 kW, wherein the multiple tube construction of the cavity
increases the surface area for radiative transfer to the reactants
in the chemical reaction over a common reaction tube, and a shape
of the reactor tubes is substantially rectangular, which also
yields a higher surface area for equivalent volume than cylindrical
shaped tubes.
10. The solar-driven chemical reactor system of claim 6, further
comprising: a tower supporting an elevated solar thermal receiver
and solar driven chemical reactor, wherein the tower is tall
enough, at least 100 meters, in height to give an optimized angle
of elevation for the non-uniform heliostat field; and each
heliostat has a mirror, where the array of mirrors in the heliostat
field are configured to obtain both 1) dense packing in at least
the first third of the part of the field near the receiver, where
the highest proportion of energy off of each of the mirrors in the
dense packed portion of heliostats intercepts the one or more
apertures or windows of the receiver and 2) optimal small shading
and minimal blocking occurs for the mirrors in the heliostat field
due to 1) the angle of elevation of the heliostat field to the
solar thermal receiver on the tower, in combination with 2) the
staggered heights and 3) the spacing of the rows of the non-uniform
heliostat field.
11. The solar-driven chemical reactor system of claim 2, further
comprising: a high concentration of solar energy directed from the
one or more solar energy concentrating fields to the receiver to
give a normal distribution equal to or greater than 3000-5000 kW
per meters squared peak solar energy in the flux at the apertures
of the receiver cavity, with an average solar energy in the
1000-2500 kW per meters squared range depending on the time of day,
in order to have a capacity of at least 2000 kW and generally
around 80,000 kW.
12. The solar-driven chemical reactor system of claim 2, wherein
the receiver cavity, the multiple reactor tubes, and the one or
more apertures are shaped and sized to facilitate greater than 60%
average aperture incident power to be converted into
chemical/sensible energy at peak incident power; and thus, greater
than 60% the amount of energy entering the receiver as solar energy
ends up as chemical or sensible enthalpy leaving the reactor tubes,
and also a conversion of carbon in the particles of biomass to CO
above 85% yield/ton of the biomass occurs from the gasification
reaction in the tubes, and wherein the receiver has one or more
windows covering the apertures and no apertures open to the
atmosphere.
13. The solar-driven chemical reactor system of claim 2, wherein
the receiver cavity, the multiple reactor tubes, and the one or
more apertures or windows are shaped and sized to map an amount of
solar flux distribution to the reactor tube size and geometric
position to allow essentially a same rate of biomass gasification
for a set biomass particle size range everywhere in a gasification
zone in the tubes of the chemical reactor, and thus avoiding
locally extremely high temperatures >1500 degrees C. or
extremely low temperatures <600 degrees C.
14. The solar-driven chemical reactor system of claim 1, further
comprising: one or more actuators, wherein the receiver has the one
or more apertures and no windows, and wherein the one or more
apertures are articulated moveable apertures that are capable of
varying location on the solar thermal receiver based on the
actuators moving the apertures, and a computing device running a
model of solar energy flux maps of the apertures that captures how
the solar power delivered to the aperture changes over time under
similar natural solar conditions in order to send control signals
to and guide the actuators in moving the apertures.
15. The solar-driven chemical reactor system of claim 1, further
comprising: one or more structures with high temperature storage
material that absorb the concentrated solar energy contained within
the cavity of the solar thermal receiver, and wherein the cavity of
the solar thermal receiver contains additional radiant heat masses,
which have high temperature storage material that absorb the
concentrated solar energy, where the radiant heat masses are used
to keep the reactor tubes hot during long periods of off sun,
during cyclic up and down times in the plant, as well as keep
radiant temperature in the reactor less transient during normal
operation, and wherein one or more of these radiant heat masses are
positioned in the cavity in areas of extremely high concentrated
solar energy compared to other areas within the cavity to absorb
some of the concentrated solar energy in that area to allow the
reactor tubes to all use the same material.
16. The solar-driven chemical reactor system of claim 2, wherein
the one or more apertures are part of a receiver outer shell that
at least partially encloses the multiple reactor tubes, wherein a
material making up the receiver inner wall absorbs, or the material
highly reflects the concentrated solar energy to cause the radiant
heat and then generally radiatively conveys that heat like an oven
to the biomass particles in the reactor tubes, and one of a brick,
a ceramic, or a fiber insulation covers an outer wall of the
receiver, wherein the inner wall operates at high >1200 degrees
C. wall temperatures and the insulation thickness is designed so as
to limit losses through conductive heat loss to less than 5% of the
energy incident at peak solar input on the receiver apertures and a
radiation shield that is moveable across the aperture at night or
other periods of extended shutdown to minimize an amount of
radiation heat loss, which enables a rapid heat up to gasification
temperatures when normal operations resume such as in the
morning.
17. The solar-driven chemical reactor system of claim 2, further
comprising: an insulation layer around the cavity of the indirect
radiation driven geometry, absorbing cavity, solar thermal
receiver, wherein the receiver is configured with only one or more
apertures and no windows, and where the multiple reactor tubes are
located in the center of the cavity; a thickness of the insulation
layer is set to control conductive heat losses, and where the
cavity temperature and an average concentration of solar energy at
the one or more apertures control radiative losses; an aperture
design, orientation, and cavity working fluid (buoyancy) are also
configured to control convective losses, wherein the inner cavity
wall at least partially encloses the multiple reactor tubes to act
like an oven, spreading heat flux around via reflection or
absorption and re-radiation and giving a much more even flux
profile on the reactor tubes, both azimuthally and axially, than
the incident solar radiation by itself has, wherein an averaging
effect on the heat flux radiated from the absorbing cavity walls
and multiple tubes occurs within the cavity; and wherein the solar
energy concentrating field is a heliostat field that focuses an
average concentrated solar energy from the moving Sun of a West
weighting to an East weighting across the aperture and subsequent
impingement on the reactor tubes themselves through the course of
each day, and yet the reactor tubes provide a uniform radial
reaction profile of the biomass particles through the course of
each day due to 1) the oven effect of the cavity along with 2) the
particle nature of biomass, which tend to average energy amongst
themselves at their design volumetric loadings, combining to give
the fairly uniform temperature profile and subsequent fairly
uniform radial reaction profile of the biomass particles.
18. The solar-driven chemical reactor system of claim 1, further
comprising: one or more incident radiation shaping surfaces
including baffles at select locations within the cavity of
receiver, along with the intertube radiation exchange between the
multiple reactor tube geometric arrangement relative to each other
is used to shape a distribution of incident radiation via
reflection or absorption within the receiver cavity.
19. The solar-driven chemical reactor system of claim 1, further
comprising: a secondary concentrator on the solar thermal receiver
to boost concentration of the concentrated solar energy, in which a
surface geometry of the secondary concentrator and a field layout
of the one or more solar energy concentrating fields is designed to
avoid reflective and radiative losses from the area surrounding the
aperture and the cavity of the solar thermal receiver; and a tower
that supports and elevates the solar thermal receiver and solar
driven chemical reactor, wherein the tower is at least 100 meters
in height to give an optimized angle of elevation, which allows for
a large number of heliostats, including over 50% of the heliostat
surface area making up the solar energy concentrating fields, to be
visible from the point of view of the secondary concentrator, which
increases the concentration of solar energy at the apertures,
improves the overall efficiency, and results in a higher plant
capital utilization factor, wherein the receiver has the one or
more apertures and no windows.
20. A solar-driven chemical reactor system, comprising: a solar
thermal receiver aligned to absorb concentrated solar energy from
one or more solar energy concentrating fields including either 1)
an array of heliostats, 2) a solar concentrating dish, or 3) any
combination of the two; a solar driven chemical reactor that has
multiple reactor tubes located inside the solar thermal receiver,
where an endothermic chemical reaction driven by radiant heat
occurs in the multiple reactor tubes using solar thermal energy
coming from the concentrated solar energy; and an aperture open to
an atmosphere of the Earth to pass the concentrated solar energy
into the solar thermal receiver to impinge on the multiple reactor
tubes and cavity walls of the receiver and transfer energy to the
reactants of the chemical reaction to drive the endothermic
chemical reaction flowing in the reactor tubes, wherein a design of
the multiple reactor tubes and solar thermal receiver are adapted
per a solar flux profile to take advantage of variations in
concentrations of solar flux in the solar flux profile including
adapting 1) an amount of reactor tubes present in the cavity, 2) a
size of the reactor tubes, 3) a geometric arrangement of the
multiple reactor tubes relative to each other, and 4) a size,
shape, and orientation of the aperture relative to the concentrated
solar energy coming from the array of heliostats.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of both U.S. Provisional
Patent Application Ser. No. 61/248,282, filed Oct. 2, 2009 and
entitled "Various Methods and Apparatuses for Sun Driven
Processes," and U.S. Provisional Patent Application Ser. No.
61/185,492, titled "VARIOUS METHODS AND APPARATUSES FOR
SOLAR-THERMAL GASIFICATION OF BIOMASS TO PRODUCE SYNTHESIS GAS"
filed Jun. 9, 2009.
NOTICE OF COPYRIGHT
[0002] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the software engine and its modules, as it appears in the Patent
and Trademark Office Patent file or records, but otherwise reserves
all copyright rights whatsoever.
FIELD OF THE INVENTION
[0003] Embodiments of the invention generally relate to systems,
methods, and apparatus for refining biomass and other materials.
More particularly, an aspect of an embodiment of the invention
relates to solar-driven systems, methods, and apparatus for
refining biomass and other materials.
BACKGROUND OF THE INVENTION
[0004] The substance/substances initially involved in a chemical
reaction are generally called reactants. Chemical reactions are
usually characterized by a chemical change in the reactants, which
then yields one or more products. Biomass gasification is an
endothermic process; energy must be put into the process to drive
it forward. Typically, this is performed by partially oxidizing
(burning) the biomass itself. Between 30% and 40% of the biomass
must be consumed to drive the process, and at the temperatures
which the process is generally limited to (for efficiency reasons),
conversion is typically limited, giving still lower yields. Also,
the chemical reactors in such traditional biorefineries are
generally engineered to operate at constant conditions around the
clock. In contrast, the proposed solar-driven chemical refinery
uses an external source of energy (solar) to provide the energy
required for reaction, so none of the biomass need be consumed to
achieve the conversion. This results in significantly higher yields
of gallons of gasoline per biomass ton than previous technologies.
As such, the energy source being used to drive the conversion is
renewable and carbon free.
SUMMARY OF THE INVENTION
[0005] Some embodiments relate to a method, apparatus, or system
for a solar-driven chemical reactor. An example system may include
a solar thermal receiver aligned to absorb concentrated solar
energy from one or more solar energy concentrating fields including
1) an array of heliostats, 2) solar concentrating dishes, and 3)
any combination of the two. Some embodiments include a solar driven
chemical reactor that has multiple reactor tubes located inside the
solar thermal receiver. The endothermic chemical reaction in the
multiple reactor tubes is driven by radiant heat. Additionally, the
multiple reactor tubes in this reactor design increase available
reactor surface area for radiative exchange to the reactants as
well as create an inter-tube radiation exchange. Additionally, the
endothermic chemical reaction can include one of the following
biomass gasification, steam methane reforming, methane cracking,
steam ethane cracking to produce ethylene, metals refining, carbon
dioxide splitting, decomposition of certain hazardous materials and
other similar endothermic carbon-based chemical reactions to be
conducted in this reactor using solar thermal energy.
[0006] Some embodiments include one or more apertures in the
receiver 1) open to an atmosphere of the Earth or 2) with a window
covering the aperture, to pass the concentrated solar energy into
the solar thermal receiver. This energy impinges on the multiple
reactor tubes and cavity walls of the receiver and transfer energy
by solar radiation absorption and heat radiation, convection, and
conduction. In this way, the energy transmitted to the reactants in
the chemical reaction drives the endothermic chemical reaction
flowing in the reactor tubes. The design of the multiple reactor
tubes and solar thermal receiver can be adapted per a solar flux
profile to take advantage of variations in the concentrations of
solar flux in the solar flux profile including adapting 1) an
amount of reactor tubes present in the cavity of the solar thermal
receiver, 2) a size diameter of each of the reactor tubes in which
a first reactor tube has a different diameter than a second reactor
tube, 3) a geometric arrangement of a shape pattern of the multiple
reactor tubes relative to each other, 4) a shape of each individual
reactor tube may vary with respect to other tubes per the flux
profile to take advantage of variations in solar flux in the
profile and 5) a size, shape, and orientation of the apertures or
windows relative to the concentrated solar energy coming from the
array of heliostats or solar concentrating dishes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The drawings refer to embodiments of the invention in
which:
[0008] FIG. 1 illustrates a block diagram of an embodiment of an
example process flow;
[0009] FIG. 2 illustrates a diagram of an embodiment of an example
multiple tube reactor;
[0010] FIG. 3 illustrates a diagram of an embodiment of an example
solar tower with receivers and heliostat field;
[0011] FIG. 4 illustrates a graph of an embodiment of particle size
distribution;
[0012] FIG. 5 illustrates a diagram of an embodiment of a solar
thermal receiver with gasifier tubes;
[0013] FIGS. 6a and 6b illustrate block diagrams of embodiments of
the entrained-flow biomass feed system;
[0014] FIG. 7 illustrates a diagram of an embodiment of a
solar-driven chemical refinery; and
[0015] FIG. 8 illustrates a flow diagram of an embodiment of the
system.
[0016] While the invention is subject to various modifications and
alternative forms, specific embodiments thereof have been shown by
way of example in the drawings and will herein be described in
detail. The invention should be understood to not be limited to the
particular forms disclosed, but on the contrary, the intention is
to cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the invention.
DETAILED DISCUSSION
[0017] In the following description, numerous specific details are
set forth, such as examples of specific data signals, named
components, connections, number of reactor tubes, etc., in order to
provide a thorough understanding of the present invention. It will
be apparent, however, to one of ordinary skill in the art that the
present invention may be practiced without these specific details.
In other instances, well known components or methods have not been
described in detail but rather in a block diagram in order to avoid
unnecessarily obscuring the present invention. Further specific
numeric references such as first reactor tube, may be made.
However, the specific numeric reference should not be interpreted
as a literal sequential order but rather interpreted that the first
reactor tube is different than a second reactor tube. Thus, the
specific details set forth are merely exemplary. The specific
details may be varied from and still be contemplated to be within
the spirit and scope of the present invention. Features found in
one embodiment may generally be used in another embodiment. The
term coupled is defined as meaning connected either directly to the
component or indirectly to the component through another
component.
[0018] In general, a method, apparatus, and system for a
solar-driven chemical reactor system can include a solar thermal
receiver aligned to absorb concentrated solar energy from one or
more solar energy concentrating fields including 1) an array of
heliostats, 2) solar concentrating dishes, and 3) any combination
of the two. Some embodiments include a solar driven chemical
reactor that has multiple reactor tubes located inside the solar
thermal receiver. In the multiple reactor tubes an endothermic
chemical reaction driven by radiant heat occurs. Additionally, the
multiple reactor tubes in this reactor design increase available
reactor surface area for radiative exchange to the reactants as
well as create an inter-tube radiation exchange. Additionally, the
endothermic chemical reaction including one or more of the
following: biomass gasification, steam methane reforming, methane
cracking, steam ethane cracking to produce ethylene, metals
refining, carbon dioxide splitting, decomposition of certain
hazardous materials, and other similar endothermic carbon-based
chemical reactions can be conducted in this reactor using solar
thermal energy.
[0019] Some embodiments include one of one or more apertures 1)
open to an atmosphere of the Earth or 2) with windows, to pass the
concentrated solar energy into the solar thermal receiver. This
energy impinges on the multiple reactor tubes and cavity walls of
the receiver and transfer energy by absorption and re-radiation,
convection, and conduction. In this way, the energy causes reacting
particles to drive the endothermic chemical reaction flowing in the
reactor tubes. The design of the multiple reactor tubes and solar
thermal receiver can be adapted per a solar flux profile to take
advantage of variations in the concentrations of solar flux in the
profile including adapting 1) an amount of the at least two or more
reactor tubes present in the cavity of the solar thermal receiver,
2) a size diameter of each of the reactor tubes in which a first
reactor tube has a different diameter than a second reactor tube,
3) a geometric arrangement of a shape pattern of the multiple
reactor tubes relative to each other, 4) a shape of each individual
reactor tube may vary with respect to other tubes per the flux
profile to take advantage of variations in solar flux in the
profile and 5) a size, shape, and orientation of the apertures or
windows relative to the concentrated solar energy coming from the
array of heliostats or solar concentrating dishes.
[0020] In some embodiments, a solar-driven chemical reactor system
may include a receiver that has two or more zones in which the
reactor tubes and the receiver cavity in each zone are made out of
different material. Different materials may be used to adapt to the
amount of solar flux in that zone, peak temperature of that zone,
or corrosion/steam conditions in that zone.
[0021] Additionally, a solar-driven chemical reactor system may
include a non-uniform heliostat field. Such a field may have, for
example, >25,000 m2 of reflecting surface. This reflecting
surface can cooperate with the solar thermal receiver to have an
ability to control an amount of solar energy flux across the
apertures or windows that is applied to reactor tubes and cavity
walls. Accordingly, this can allow enough energy from the radiant
energy to raise the heat to initiate and sustain a sufficiently
high temperature so that the gasification occurs of greater than 90
percent of the biomass particles into reactant products.
[0022] FIG. 1 illustrates a block diagram of an example process
flow. Some embodiments encompass a solar-driven-biomass
gasification to liquid fuel/electrical process. The process might
also include electrical generation, chemical processing, or
bio-char, for solar generated syngas derivative product or other
similar technical process. In a specific example implementation the
process described is a solar-driven-biomass gasification to `green`
liquid fuel process. In an embodiment, this process includes one or
more of the following process steps.
[0023] Biomass grinding or densification, transport, and then
offload 100 may be part of the overall process. Bales of the
biomass can be compressed and densified by a compactor to
facilitate transport to on-site via the densification achieved by
the compression and the bales are sized to dimensions that may, for
example, fit within a standard boxcar size or shipping container
size to fit within standard compactor size. The entrained-flow
biomass feed system can be preceded by a grinding system equipped
with mechanical cutting device and a particle classifier, such as a
perforated screen or a cyclone, to control the size of the
particles that are. The grinding system that has a mechanical
cutting device such as a screw and set of filters with micron sized
holes/screen diameter sized holes to control particle size. The
biomass may be in an embodiment non-food stock biomass. In some
cases, food stock biomass might also be processed.
[0024] The biomass may then be stored 102. As needed, the biomass
might be fed 104 into an example system or apparatus of the instant
application. For example, after grinding and pulverizing the
biomass to particles, the particles of biomass can be fed into and
gasified in the solar-driven chemical reactor. An entrained gas
biomass feed system uses an entrainment carrier gas to move a
variety of biomass sources fed as particles into the solar driven
chemical reactor. Two or more feed lines supply the particles of
biomass having an average smallest dimension size between 50
microns (um) and 2000 um to the chemical reactor.
[0025] A solar receiver and gasifier 106 may be used to break down
the biomass. An example biomass gasifier design and operation can
include a solar chemical reactor and solar receiver to generate
components of syngas. The amount, size, and material of the reactor
tubes in the gasifier 106 may be adapted per the flux profile to
take advantage of variations in solar flux in the profile. Various
heliostat field designs and operations to drive the biomass
gasifier might be used. Some example systems may include a solar
concentrator, secondary concentrator, focused mirror array, etc. to
drive biomass gasifier 110.
[0026] Quenching, gas clean up, and ash removal from biomass
gasifier 108 may be provided for. Some non-pilot syngas may exit
the system 112. Some gasses may be a waste product, while other
gasses can be compressed 114 prior to e.g. storage 118 or methanol
synthesis 116. Methanol may then be stored 120 for later use or
methanol to gasoline conversion 122.
[0027] In various embodiments, synthesis gas may be fed to another
technical application. Examples include a syngas to other chemical
conversion process. The other chemical or chemicals produced can
include liquefied fuels such as transportation liquefied fuels. In
an example, hydrocarbon based fuel methanol 116 may be formed from
syngas. The methanol may be further processed to gasoline or other
fuels 122 and various products may be separated out from the
gasoline 124 or syngas. These products, e.g., gasoline, may be
stored for later use as an energy source. Thus, an on-site chemical
synthesis reactor may be geographically located on the same site as
the syngas chemical reactor and integrated to receive the hydrogen
and carbon monoxide products from the gasification reaction. This
on-site chemical synthesis reactor has an input to receive the
hydrogen and carbon monoxide products in a hydrocarbon fuel
synthesis process performed in the on-site chemical synthesis
reactor to create hydrocarbon fuels and/or chemicals. In an
embodiment, the on-site chemical synthesis reactor is an on-site
fuel synthesis reactor that creates liquid hydrocarbon fuels.
[0028] FIG. 2 illustrates a diagram of an example multiple tube
chemical reactor 200 that may be used in a solar driven system.
Reactor 200 has multiple reactor tubes 202, 204, 206, 208. A
separate feed/entrainment line may be used for each of the gasifier
reactor tubes 202, 204, 206, 208 in the chemical reactor 200. This
may allow for independent temperature control and balancing of
amount of particles of biomass or other gases flowing in each of
the reactor tubes 202, 204, 206, 208 in the multiple tube solar
driven chemical reactor 200. The particles of biomass feed can be
distributed to the reactor tubes 202, 204, 206, 208 by a lock
hopper rotary feed system, such as a Rotofeed.RTM. lock hopper
rotary feed system. Such a system can allow for balanced feeding to
individual reactor tubes 202, 204, 206, 208 and feed rate of the
particles is controlled by a weight measuring metering device such
as load cells.
[0029] A biomass gasifier reactor and receiver control system and
chemistry control system may include a feed-rate control system
that manages variations in solar energy. The sources of
concentrated solar energy to the solar thermal receiver includes
one or more solar energy concentrating fields consisting of 1) an
array of heliostats, 2) solar concentrating dishes, and 3) any
combination of the two. The design of the multiple reactor tubes
and solar thermal receiver are adapted per a solar flux profile to
take advantage of variations in the concentrations of solar flux in
the solar flux profile. These adaption can include, for example,
adapting 1) an amount of the at least two or more reactor tubes
present in the cavity of the solar thermal receiver, 2) a size
diameter of each of the reactor tubes in which the reactor tubes
may have different diameters, 3) a shape pattern of the multiple
reactor tubes relative to each other, 4) a shape of each individual
reactor tube may vary with respect to other tubes 5) a size, shape,
and orientation of the apertures or windows relative to the
concentrated solar energy coming from the array of heliostats or
solar concentrating dishes, 6) and other similar adaptations.
[0030] The solar driven chemical reactor 200 can be contained
within the solar thermal receiver. The inner walls of the solar
thermal receiver and the chemical reactor 200 may be made from
materials selected to transfer energy by primarily heat radiation,
along with convection, and conduction to the reacting biomass
particles to drive the endothermic gasification reaction of the
particles of biomass flowing through the chemical reactor.
[0031] Some embodiments may include a computerized control system
configured to balance the gasification reaction of biomass
particles with the available concentrated solar energy and
additional variable parameters of a fixed range of particle size,
temperature of the chemical reactor 200, and residence time of the
particles in a reaction zone in the chemical reactor. This may be
done so that an overall biomass particle conversion remains above a
threshold set point with substantial tar destruction to less than
below 50 mg/m 3 and gasification of greater than 90 percent of the
particles into reaction products that include hydrogen and carbon
monoxide gas.
[0032] A feedforward portion and a feedback portion of the computer
control system may be used to adapt to both long and short term
disturbances in available solar energy. For example, the
feedforward portion may anticipate, for example, either or both
immediate and short-term changes, or cyclic changes in solar energy
due to at least a time of day, day of the calendar it is, and
periodic weather reports, such as daily or hourly weather reports.
The anticipation may be generated with a predictive model that
adapts to the anticipated cyclic changes. The feedback portion
measures actual process parameters including the temperature of the
chemical reactor at an entrance and an exit. Additionally, the
system may compensate for missing data, such as missing weather
reports.
[0033] The computerized control system may send a feed demand
signal to the feed system to control a feed rate of particles of
biomass in the solar driven chemical reactor by changing a gas
pressure and/or volumetric flow rate of the entrainment carrier gas
in combination with a metering device controlling a weight, volume,
or quantity of biomass particles from a lock hopper to the feed
lines that feed the chemical reactor. The computerized control
system may be one of a Programmable Logic Controller, computer,
computer numerical controlled machine, similar control system,
etc.
[0034] As discussed, the solar-driven bio-refinery can include a
chemical reactor 200 that has multiple reactor tubes 202, 204, 206,
208 in which the biomass particles flow in. Two or more reactor
tubes in the chemical reactor tubes might be used. The example
illustrated includes five reactor tubes. The fixed range of
particle size of biomass used can be controlled to an average
smallest dimension size between 50 microns (um) and 2000 um, with a
general range of between 200 micrometer and 1000 micrometer.
Additionally, the temperature at an exit from the tubes 202, 204,
206, 208 of the chemical reactor may be maintained at a steady
state temperature exceeding 1000 degrees C., above transitory
minimum temperature of 800 degrees C. and below peak temperatures
of 1600 degrees C. Further, the residence time of the particles in
the reaction zone in the chemical reactor 200 can be between a
range of 0.01 and 5 seconds.
[0035] Some embodiments include two or more sensors including
temperature sensors at the entrance and exit of the chemical
reactor and one or more light meters to provide information to the
feedback portion of the computer control. This information can
include an amount of solar energy available indicated by
system.
[0036] A separate feed line can be used to feed biomass particles
for each of the reactor tubes 202, 204, 206, 208 in the chemical
reactor 200, which can allow independent temperature control and
balancing of the amount of particles of biomass flowing in each of
the reactor tubes in the multiple tube solar driven chemical
reactor.
[0037] The receiver cavity, the multiple reactor tubes, and the one
or more apertures or windows are shaped and sized to facilitate
greater than 60% average aperture/window incident power to be
converted into chemical/sensible energy at peak incident power; and
thus, greater than 60% the amount of energy entering the receiver
as solar energy ends up as chemical or sensible enthalpy leaving
the reactor tubes, and also a conversion of carbon in the particles
of biomass to CO (and in some cases, CH.sub.4 or other
hydrocarbons) above 85% yield of the biomass occurs from the
gasification reaction. In some embodiment, the apertures or windows
are shaped and sized to facilitate greater than 75% average
aperture/window incident power to be converted into
chemical/sensible energy at peak incident power.
[0038] In some embodiments, the receiver cavity, the multiple
reactor tubes, and the one or more apertures or windows are shaped
and sized to map an amount of solar flux distribution to the
reactor tube size and geometric position to allow essentially a
same rate of biomass gasification for a set biomass particle size
range everywhere in a gasification zone in the tubes of the
chemical reactor, and thus avoiding locally extremely high
temperatures (>1500 C) or extremely low temperatures (<600
C).
[0039] FIG. 3 illustrates a diagram of an example solar tower 300
with receivers 302 and heliostat field 304. In some embodiments
solar tower 300 may be used to from a solar-driven bio-refinery
with an entrainment flow biomass feed system. The feed system can
be feedstock flexible via, for example, particle size control of
the biomass.
[0040] A chemical reactor 306 receives concentrated solar thermal
energy from an array of heliostats 304. The chemical reactor 306
can be, for example, a multiple reactor tube, downdraft, solar
driven, chemical reactor, which receives concentrated solar thermal
energy from the array of heliostats. A solar tower 300 may form a
portion of a solar-driven bio-refinery that may also include a
biomass feed system that has balancing of the feed lines to each of
the reactor tubes in a multiple tube chemical reactor. For example,
biomass may be feed to the solar reactor 306 in an operation
including three parts: biomass transport and preparation for
feeding to the solar tower reactor 306, biomass transport to the
top of the, e.g., 500+ foot tower 300, and distribution into the
specific downdraft tubes of the reactor 306. The distribution may
be performed via multiple stages.
[0041] The tower 300 supporting the elevated solar thermal receiver
302 and solar driven chemical reactor 306 is tall enough, such as
at least 150 meters, in height to give an optimized angle of
elevation for the non-uniform heliostat field. In some embodiments,
a height of at least 100 meters may provide an optimized angle of
elevation for the non-uniform heliostat field.
[0042] Thus, the tower 300 that supports and elevates the solar
thermal receiver 306 and solar driven chemical reactor 302 can use
a tower that is at least 100 meters in height to give an optimized
angle of elevation. This may allow for a large fraction of the
heliostat area, such as over 50%, to be visible from the point of
view of the secondary concentrator. This, in turn, may increase the
concentration of solar energy at the apertures, improves the
overall efficiency, and results in a higher plant capital
utilization factor. The solar energy may enter the receiver through
one or more apertures. In some embodiments, the tower may be 50
meters or higher in height.
[0043] In some embodiments, each heliostat has a mirror. The array
of mirrors in the heliostat field are configured to obtain both 1)
dense packing in at least the first third of the part of the field
near the receiver and 2) optimal small shading. The highest
proportion of energy off of each of the mirrors in the dense packed
portion of heliostats intercepts the one or more apertures or
windows of the receiver. Optimal small shading and minimal blocking
occurs for the mirrors in the heliostat field due to 1) the angle
of elevation of the heliostat field to the solar thermal receiver
on the tower, in combination with 2) the staggered heights and 3)
the spacing of the rows of the non-uniform heliostat field. In an
embodiment, the heliostats may have a long focal point.
[0044] In some embodiments, a solar-driven chemical reactor can
include a high concentration of the sun's energy directed from the
one or more solar energy concentrating fields to the receiver to
give a normal distribution equal to or greater than 3000-5000 kW
per meters squared peak solar energy in the flux at the apertures
of the receiver cavity. In another embodiment, the flux at the
apertures of the receiver cavity may have an average solar energy
of 750-3500 as the useable/achievable range, and the preferred
range of 1000-2500 kW/m.sup.2 range depending on the time of day,
in order to have a capacity of at least 2000 kW and generally
around 80,000 kW. In one example, the multiple tube construction of
the cavity increases the surface area for radiative transfer to the
reactants in the chemical reaction over a common reaction tube. The
receiver may have high fluxes of 3000-5000 kW per meters squared
peak solar energy right at the aperture but these fluxes fall off
as the light approaches the reactor tubes and tube wall to 100-300
kW/m.sup.2.
[0045] Some embodiments can include one or more actuators. The
receiver has the one or more apertures that are not covered with a
window. The one or more apertures can be articulated moveable
apertures that are capable of varying location on the solar thermal
receiver, e.g., on top of the tower 300. These movements may depend
on the time of day or season of the year and be based on the
actuators moving the apertures.
[0046] A computing device, such as a PLC controller, a computer,
etc., may run a model of solar energy flux maps of the apertures
that captures how the solar power delivered to the aperture changes
over time under similar natural solar conditions in order to send
control signals to and guide the actuators in moving the
apertures.
[0047] The cavity of the solar thermal receiver may contain
additional radiant heat masses, which have high temperature storage
material that absorb the concentrated solar energy. The structures
may be used as radiant heat masses to keep the reactor tubes hot
during long periods of off sun, during cyclic up and down times in
the plant, as well as keep radiant temperature in the reactor more
stable/less transient during normal operation. One or more of these
radiant heat masses can be positioned in the cavity in areas of
extremely high concentrated solar energy compared to other areas
within the cavity to absorb some of the concentrated solar energy
in that area to allow the reactor tubes to all use the same
material. These radiant heat masses may also be heated by non-solar
sources such as gas burners or electrical devices.
[0048] One or more apertures or 2) windows can be part of a
receiver outer shell that at least partially encloses the multiple
reactor tubes 202, 204, 206, 208. The size and shape of the one or
more apertures may be determined by the heliostat field, which can
focus into the apertures or windows a total amount of light in sun
concentrations that is needed for the short residence times
balanced against an efficiency of a solar energy being concentrated
from the non-uniform heliostat field.
[0049] Additionally, a material making up the receiver inner wall
may absorb concentrated solar energy, or may be a material that
highly reflects, such as refractory alumina or SiC plate, to cause
the radiant heat and then generally radiatively conveys that heat
like an oven to the biomass particles in the reactor tubes. An
insulation of brick, ceramic, or fiber with a thickness of, for
example, 24 cm covers an outer wall/shell of the receiver. The
inner wall may operate at high (>1200.degree. C.) wall
temperatures and the insulation thickness is designed so as to
limit losses through conductive heat loss to less than 5% of the
energy incident at peak solar input on the receiver apertures or
windows. A radiation shield, such as a door, that is moveable
across the aperture at night or other periods of extended shutdown
is used to minimize an amount of radiation heat loss, which enables
a rapid heat up to gasification temperatures when normal operations
resume such as in the morning. In some embodiments, the insulation
thickness and door are designed so as to limit losses through
conductive heat loss to less than 2% of the energy incident at peak
solar input on the receiver.
[0050] An insulation layer can be included around the cavity of the
indirect radiation driven geometry, absorbing cavity, and solar
thermal receiver. The receiver might have one or more apertures and
no windows. Additionally, the cavity of the receiver may also have
a high concentration of solar energy at the one or more apertures.
The multiple reactor tubes are located in the center of the cavity.
The thickness of the insulation layer can be set to control
conductive heat losses. In some examples, radiative losses may be
controlled by the cavity temperature and an average concentration
of solar energy at the one or more apertures.
[0051] The solar thermal receiver may further include a thick layer
of insulation that limits heat losses by conduction from a cavity
of the receiver. A moveable insulative door on the receiver
aperture limits heat losses by radiation from the cavity during
periods of inclement weather or during nighttime, so that the
temperature in the cavity is decreased by less than 400.degree. C.
in a 12-hour period when no concentrated solar energy is directed
at the cavity aperture. The door and insulation reduce the amount
of time required to heat the receiver following a down period and
lessen the thermal shock and stresses imparted to the receiver and
reactor materials. In some embodiments, the receiver may include a
pump to move molten salts through tubes in the receiver walls for
use in electrical power generation.
[0052] In some embodiments, an aperture design, orientation, and
cavity working fluid (buoyancy) may be set to control convective
losses The cavity may at least partially enclosing the multiple
reactor tubes and may acts like an oven, spreading heat flux around
through radiation. In this way, the system can give a much more
even flux profile on the reactor tubes (azimuthally and axially)
than the incident solar radiation has. Accordingly, an averaging
effect on the heat flux radiated from the absorbing cavity walls
and multiple tubes occurs within the cavity.
[0053] Some embodiments include an axis of the reactor tubes with a
heliostat solar field that focuses the moving Sun to shift the
concentrated solar energy from a West to an East weighting across
the aperture impinging on the axis of the reactor tubes themselves
through the course of each day. The oven effect of the cavity,
along with the particles, may tend to average energy amongst
themselves at their design volumetric loadings and combine to give
a fairly uniform temperature profile and subsequent fairly uniform
reaction profile of the biomass particles.
[0054] One or more incident radiation shaping surfaces such as
baffles may be used on the reactor tubes. These baffles may be
positioned at select locations within the cavity of receiver and
combined with an intertube radiation exchange between the multiple
reactor tube geometric arrangement relative to each other is used
to shape a distribution of incident radiation via reflection or
absorption within the receiver cavity.
[0055] A secondary concentrator on the solar thermal receiver may
be used to boost concentration of the concentrated solar energy, in
which a surface geometry of the secondary concentrator and a field
layout of the one or more solar energy concentrating fields is
designed to avoid reflective and absorptive losses in the cavity of
the solar thermal receiver.
[0056] FIG. 4 illustrates a graph of cumulative particle size
distribution. The graph illustrates the weight percentage below Y
percentage for a given screen size in microns. Four example
materials are illustrated, knife-chopped rice straw at 48
kilowatt-hours per ton, knife-chopped rice straw with an unknown
energy value per ton, miscanthus stems at 35 kilowatt-hours per
ton, and rice straw at 190 kilowatt-hours per ton. The smaller the
size of the particle of the various types of biomass, the less
difference in the way the feed system and reactor view particles
from different types of biomass. The average size of ground
particles may be correlated to filter particle size used in
standard filter ranges.
[0057] In one embodiment a material and an indirect gasification
design of the multiple reactor tubes allows for feedstock
flexibility in the type of biomass making up the particles of
biomass. This can obviate a need for an exothermic/endothermic
reaction balancing because heat radiation from the concentrated
solar energy primarily drives the endothermic gasification reaction
and the heat radiation-based heat transfer balancing makes the
endothermic reaction gasification quite forgiving in terms of
internal reaction balance. Thus, at least two or more different
types of biomass materials might be used in the same reactor tube
geometry. This obviates any need for a complete reengineering when
a new type of biomass feedstock is used. The two or more different
types of biomass materials that can be fed from the feed system,
individually or in combinational mixtures, are selected from the
group consisting of rice straw, rice hulls, corn stover, switch
grass, non-food wheat straw, miscanthus, orchard wastes, sorghum,
forestry thinning, forestry wastes, source separated green wastes
and other similar biomass sources. These sources might be used
interchangeable as long as a few parameters are controlled such as
the particle size of the biomass.
[0058] FIG. 5 illustrates a diagram of a solar thermal receiver 500
with gasifier tubes 502. Solar thermal receiver 500 can form a
portion of a solar-driven bio-refinery. The solar-driven
bio-refinery can include a solar-driven chemical reactor, a solar
thermal receiver such as receiver 500, or both as shown in FIG. 5.
In some embodiments, solar thermal receiver 500 can be a multiple
reaction tube downdraft solar thermal receiver as well as
solar-driven chemical reactor. Additionally, the feed system may
feed biomass particles into the multiple reaction tubes 502, in
which the particles of biomass may be gasified in the presence of
steam at a temperature exceeding 950 degrees C. from an exit of a
gasification reaction zone of the reactor tubes. The tubes
arrangement, diameters, and shape are adapted to the flux
profile.
[0059] The size and shape of one or more apertures in the receiver
and the current temperature of the cavity of the receiver enclosing
the chemical reactor can be set to make radiation losses directly
calculable. An insulation layer around the cavity may be set thick
enough to control conduction losses to, e.g., less than 2% of the
peak solar input, wherein once the reactor is heated up to
operational temperatures, due to the conduction losses to less than
2% and the radiation losses being directly calculable the receiver
cavity temperature is a controlled parameter. The receiver cavity
temperature may then be primarily controlled by modulating the flow
rate of biomass particles through the reactor tubes balanced
against the predicted feed-forward available amount of solar energy
and the dynamically determined feedback amount of available solar
energy.
[0060] Some embodiments may include one or more apertures that may
be open to the atmosphere or covered in a transparent window, to
pass the concentrated solar energy into the solar thermal receiver
to impinge on the multiple reactor tubes and cavity walls of the
receiver and transfer energy by solar radiation absorption and heat
radiation, convection, and conduction to the reactants in the
chemical reaction, such as the particles of biomass.
[0061] This transfer of energy may drive the endothermic chemical
reaction flowing in the reactor tubes. The design of the multiple
reactor tubes and solar thermal receiver can be adapted per a solar
flux profile to take advantage of variations in the concentrations
of solar flux in the profile. For example, adapting can include 1)
an amount of the at least two or more reactor tubes present in the
cavity of the solar thermal receiver, 2) a size diameter of each of
the reactor tubes in which a first reactor tube has a different
diameter than a second reactor tube, 3) a geometric arrangement of
a shape pattern of the multiple reactor tubes relative to each
other, 4) a shape of each individual reactor tube may vary with
respect to other tubes per the flux profile to take advantage of
variations in solar flux in the profile, i.e., areas with larger
amounts of direct and incident solar flux as well as adapt for
areas with a lower amount of solar flux; and 5) a size, shape, and
orientation of the apertures or windows relative to the
concentrated solar energy coming from the array of heliostats or
solar concentrating dishes.
[0062] Materials selected for the inner cavity wall and the reactor
tubes and an amount of concentrated solar energy from one or more
solar energy concentrating fields combine to cause high heat
transfer rates from the cavity walls and reactor tubes. The
endothermic chemical reaction can be biomass gasification. The high
heat transfer rates allow particles of biomass flowing in the
reactor tubes to achieve a high enough temperature necessary for
substantial tar destruction and gasification of greater than 90
percent of the biomass particles into reaction products including
hydrogen and carbon monoxide gas in a very short residence time
between a range of 0.01 and 5 seconds.
[0063] The length and diameter dimensions of a gasification
reaction zone of each of the reactor tubes, along with an
arrangement and an amount of the tubes are matched to an amount of
sun concentration from the heliostat field to give the fast
residence time of 0.01 second to 5 seconds, with the preferred
residence time of 0.5-3 seconds, at the biomass gasification
temperatures. The multiple tubes may have different diameters such
as a larger diameter than another tube in the multiple tubes. The
larger diameter tubes can be located in a higher solar energy
concentration and higher temperature zone in the cavity of the
receiver. Additionally, the geometrical configuration of the
multiple reactor tubes in the receiver relative to each other is in
a linear pattern, semi circular pattern, arc pattern, cylindrical
pattern, rectangular pattern, or other appropriate configuration.
An inner diameter of the tubes may be sized to allow a
substantially uniform gasification of the biomass particles from
the edges to the center of the tube. The wall thickness of the
tubes may be in a range of 1/8''-2'' to withstand at least a 75
psig pressure on the inside tube walls at 1400.degree. C.
[0064] For example, the tubes can be oriented vertically in the
solar receiver cavity, and may be 2-30'' (3-16'' preferred) in
inner diameter with a 1/8''-2'' wall thickness to withstand the 75
psig pressure on the inside tube walls. The arrangement, shape, and
pattern of a group of tubes may be an arc, cylinder, rectangle, or
a semi circle in shape. In general, more thermal energy is
available at the top of the group shape without a presence of a
secondary concentrator. The more tubes equals more surface area
than one big tube and more uniform heating because diameter is
smaller than one big tube. Additionally, the receiver shape may not
be cylindrical when used with a multiple receiver tower site. The
more even temperature profile is obtained in the more central tubes
as opposed to the outer tube, giving a longer residence time at
high temperature. The first reactor tube is located above the
second reactor tube. The higher oven temperature zone may have the
bigger tubes in diameter, as well as the bigger diameter tubes may
be located in other areas of the receiver.
[0065] Some embodiments include a receiver that has two or more
zones in which the reactor tubes and the receiver cavity in each
zone are made out of different material. This can be done to adapt
to an amount of solar flux in that zone, a peak temperature of that
zone, and corrosion/steam conditions in that zone. Additionally,
the shape of each tube can be a cylindrical shaped pipe or of
another geometry such as a rectangular shaped pipe, for example.
The shape of the reactor tubes being substantially rectangular will
yields a higher surface area for equivalent volume than cylindrical
shaped tubes.
[0066] In an embodiment, the amount of reactor tubes present in the
cavity of the solar thermal receiver will be in a preferred range
of 120-150 reactor tubes, with a range encompassing as few as 30
reactor tubes and as many as multiple 100 s. Each reactor tube will
have the same size diameter the rest of the reactor tubes. The
geometric arrangement of the multiple reactor tubes relative to
each other will be arc pattern with probably more than one row. The
shape of each individual reactor tube will all be cylindrical. The
expected size, shape, and orientation of the aperture in the
receiver relative to the concentrated solar energy coming from the
array of heliostats or solar concentrating dishes will be
approximately 7 meters by 7 meters square. The length and diameter
dimensions of the gasification reaction zone in the reactor tubes
is the inner diameter of the tubes will be 6 inches and stretch the
full length of the tube such as 9 meters long.
[0067] A tower 300 that supports and elevates the solar thermal
receiver and solar driven chemical reactor may be used in some
embodiments. The tower 300 is at least tall enough, such as equal
to or greater than 100 meters, in height to give an optimized angle
of elevation for the one or more solar energy concentrating fields
to supply the concentrated solar energy to the solar thermal
receiver and solar driven chemical reactor while minimizing an
amount of heliostats or solar concentrating dishes and acreage of
land occupied by these heliostats or solar concentrating dishes
needed to deliver an amount of concentrated solar energy to the
apertures or windows of 750-3500 kW m.sup.-2 as the
useable/achievable range. The concentrated solar energy to the
apertures or windows exceeding 750 kW m.sup.-2 achieves the high
heat transfer rates of the inner wall of the cavity and reactor
tubes causes the particles biomass to achieve the high enough
temperature necessary for substantial tar mitigation and
gasification of greater than 90 percent of the biomass particles
into reactant products.
[0068] FIGS. 6a and 6b illustrate block diagrams of embodiments of
the entrained-flow biomass feed system 600. Different types of feed
systems may be used in conjunction with a biomass into reactor, for
example, drop tube, total solid feed into the reactor, slurry fed
into the reactor, a moveable bed in the reactor, or combinations of
these schemes.
[0069] One or more feeding vessels in the biomass feed system
supply two or more reactor tubes in the solar-driven chemical
reactor. Each of the feeding vessels has one or more outlets
configured to supply a consistent volumetric amount of biomass
particles within 10 percent of the demand signal amount when
distributing biomass particles to the two or more reactor tubes.
For example, the injection rate to each injection point into
carrier gas lines is within +/-10% of the desired demand signal
amount.
[0070] One example solar-driven bio-refinery may include the
entrained-flow biomass feed system 600 that includes or otherwise
cooperates with a grinding system. The grinding process 603 and
feed process may be 1) processes separated in time and completed
independently of the other process or 2) a continuous process of
the where the grinding process 603 occurs and immediately feeds
biomass into the feed system and then into the chemical
reactor.
[0071] An objective of the feeding system is to feed as many
reactor tubes as possible with the fewest number of feeding vessels
such as lock-hopper systems.
[0072] The grinding system 603 has a mechanical cutting device used
to grind the biomass into primary particles, which are to be fed
into the solar driven chemical reactor. The grinding system
supplies primary particles that have an average smallest dimension
size between 200 microns (um) and 2000 um, with a general range of
between 500 um and 1000 um to a lock hopper system 604 with a
standard belt conveyer. The biomass particles are then fed across a
pressure boundary into a pressurized entrainment gas for feeding
into in the solar driven chemical reactor. The feeding vessel may
use an Auger/Screw feeder or an airlock-type rotational solids
feeding/rate metering device.
[0073] As illustrated in FIG. 6a, the entrainment-flow biomass feed
system 600 can include a pressurized lock hopper 604 that feeds the
biomass to a rotating screw conveyor 602 and a metering device and
then into an entrainment gas pipe at the lock hopper exit 606. A
flow splitter distributes the particles of biomass into multiple
entrainment gas lines to feed at least two or more of the multiple
reactor tubes making up the solar driven chemical reactor. The
entrainment gas for the entrainment flow biomass feed system may be
a pressurized dry steam generated from waste heat recovered from
either 1) the methanol/Methanol-To-Gasoline (MTG) units in the
hydrocarbon fuel synthesis process 2) the products from the
gasification reaction in the solar driven chemical reactor 3) other
gases such as natural gas, carbon dioxide or 4) combinations
thereof.
[0074] As illustrated in FIGS. 6a and 6b, the feed rate of the
biomass particles can be controlled by a metering device and
controlling a rotational rate of a screw 602 or other rotational
device at a base of the lock hopper 604, which responds to a feed
demand signal received from the computerized control system.
[0075] Some embodiments may also allow for controlling the
rotational rate of the screw or auger 602 that can move set amounts
of biomass along the axis of rotation of the auger 602. The auger
602 may be located at the base of the lock hopper 604 and can be
controlled by a computerized control system such as a Programmable
Logic Controller, or via different data communication protocols
using a Personal Computer, Macintosh Computing device, CNC, various
combinations of these systems, etc, to respond to feed demand of
the system. In an embodiment, the computerized control system
controls the feed rate of particles of biomass in the solar driven
chemical reactor based on an amount of solar energy available
indicated by sensors including temperature sensors and/or light
meters.
[0076] FIG. 7 illustrates a diagram of a solar-driven chemical
refinery 800. In such a system, solar power from a concentrating
field 802 may be provided through a window or aperture 804 to a
solar heated reactor chamber 806. An array of heliostats 802 can be
used to focus light onto the aperture 804 of receiver around the
reactor 806. A quencher 808 may be used to prevent back reaction.
As illustrated, biomass particles flow into the system at 810 and
syngas flows out. Additionally, a heat exchange may occur to recoup
waste heat from the exiting biomass particle remnants and the
syngas.
[0077] In some embodiments, steam may be injected along with the
particles of biomass during the gasification reaction. This may
shift some of the product carbon monoxide to additional hydrogen
and carbon dioxide gas, making the hydrogen to carbon monoxide
ratio appropriate for methanol synthesis. In such an embodiment,
the inside walls of the reactor tubes may be are made of corrosion
resistant materials with a resistance to steam of between a good to
excellent rating.
[0078] In some embodiments, a composition analyzer at the exit of
the reactor system may be used to sense changes in hydrogen, carbon
monoxide, carbon dioxide, water, methane and tar composition of the
syngas. The composition analyzer provides a dynamic signal to the
feedback portion of the control system. Upon readings of reaction
product components that are too high above a threshold, the control
system can divert the reactant products to a reactor recycling line
or to a flare to avoid damage to compressors, catalytic systems,
and other components in the methanol synthesis plant.
[0079] In some embodiments, a carrier gas supply line can supply
the entrainment gas as a pressurized dry steam. Natural gas may be
fed along with the biomass particles during a co-gasification of 1)
biomass in the presence of steam and 2) steam reforming of natural
gas.
[0080] In reactor 806 biomass particles can be reduced to syngas,
which in turn can be synthesized into liquid fuel in liquid fuel
synthesizer 808. Examples of liquid hydrocarbon fuel include, but
are not limited to one or more of jet fuel, DME, gasoline, diesel,
methanol, and mixed alcohol, synthetic natural gas production, and
heating oil generation.
[0081] In some embodiments, an amount of surface area, thermal
mass, and heat capacity may be built into two or more reactor tubes
and receiver cavity. One or more temperature sensors at the
entrance and exit of the reactor tubes may be used to monitor the
solar-driven bio-refinery. An operational temperature range of
below 1600 degrees C. and above 800 degrees C. in the chemical
reactor might be achieved during daily weather conditions, which
are subject to rapid changes in solar availability.
[0082] In some embodiments, a feed demand signal from the control
system can be used to control the feed rate of particles of biomass
in the solar driven chemical reactor. This control can be performed
using a feedforward/feedback model-predictive scheme. Such a scheme
might be used in cooperation with designing in enough surface area,
thermal mass, and heat capacity in the multiple tubes and receiver
cavity to ensure that temperature of the reactor cavity remains in
the operational temperature range of below 1600 degrees C. and
above 800 degrees C. These temperatures might be maintained during
rapidly changing daily weather conditions. In some examples, the
feed forward model can predict a maximum, minimum, and average
available solar energy over each time period in a given day as well
as each day throughout the year.
[0083] The feed-forward portion utilizes a histogram of events
affecting an amount of available solar energy categorized into at
least three general time durations. Events may further be
categorized as short events of 1 to 5 hours, often caused by
passing clouds; medium events of 5-14 hours, often caused by
diurnal effects (for our mid latitudes), long term events of 14
hours or more, generally caused by more major weather events. The
time of day, the day of the calendar and the daily weather report
may also be considered with respect to feed-forward
implementations.
[0084] The feedback portion may receives dynamic feedback from
temperature sensors and combine this data to maintain both the
quality and output of resultant syngas at above a threshold set
point of substantial tar destruction to maintain tar at or below 50
mg/m.sup.3 and gasification of greater than 90 percent of the
biomass particles into the reaction products. In one example,
enough surface area and thermal mass of the cavity and reactor
tubes is built into the multiple tubes and receiver cavity in
relation to the feed rate of biomass particles, to act as a
ballast, averaging out very short term small fluctuations (second
to second) in the available solar energy. This thermal mass causes
a very low ramp-up and ramp-down of temperature of the reactor due
to these instantaneous changes in available solar energy; and
thereby, allow the ramp-up and ramp-down of the feed rate of
biomass particles to be gradual as well.
[0085] In some embodiments, the control system can use a complex
feedforward/feedback model-predictive scheme to ensure that
temperature of the reactor cavity remains in the required range.
The feedforward components use meteorological measurements,
geographical factors, and time of day/day of year to predict the
rate of change of available solar energy and make process
adjustments accordingly. Additionally, the feedback component of
the control checks these predictions against real time data to make
appropriate corrections balanced by not overcorrecting or under
correcting for the instantaneous changes in solar energy
conditions. This control approach gives robust system operation
with a highly transient system input: sunlight.
[0086] In some embodiments, the carbonaceous biomass material
particles being fed from the entrained flow biomass feed system
undergo several distinct chemical processes of the gasification
reaction prior to exiting the reactor tubes. These processes
include pyrolysis of the carbonaceous biomass particles into 1)
carbonaceous char and 2) volatile components vaporized into gas
products. The process also include gasification of the carbonaceous
char including the lignin fractions into both 1) gaseous products,
including carbon monoxide, hydrogen, and tars, as well as 2)
greater than 99% pure carbonaceous ash. The process includes
cracking of the tars including larger hydrocarbons and aromatic
compounds collectively known as tars. This gasification can occur
at greater than 1000 degrees C. to the produce the substantial tar
destruction to less than 50 mg/m.sup.3 and gasification of greater
than 90 percent of the biomass particles into reaction products
including hydrogen and carbon monoxide gas. The steps of
gasification and cracking of tars starts and finishes within the
residence time of the biomass particles in the reaction zone in the
chemical reactor between the range of 0.01 and 5 seconds.
[0087] As discussed above, in various embodiments, gasification of
the carbonaceous char including lignin occurs. Lignin is a complex
chemical compound derived from biomass, and an integral part of the
secondary cell walls of plants. Lignin fills the spaces in the cell
wall between cellulose, hemicellulose, and pectin components.
Additionally, preheating of the biomass prior to being fed into the
reactor tubes may raise the temperature above 200 degrees C.
beginning the pyrolysis process.
[0088] In some embodiments, the shape and width of the outlet of
the feed line pipe carrying the biomass particles to its
corresponding reactor tube may be used to control a dispersion
pattern of biomass particles entering each reactor tube. Greater
than 90% conversion may occur because of both 1) the high operating
temperatures and 2) that the biomass particles are well separated
from one another in a flowing dense cloud of very fine biomass
particles. An amount of oxygen, air, or steam co-currently flowing
in the gasification of the biomass particles can be controlled to
cause a selectivity of carbon reactant from the biomass to become
CO rather than CO2 at better than a 10:1 selectivity to CO over
CO2.
[0089] In various embodiments, the control system can use both
feedforward (based on anticipated changes) and feedback (based on
actual measured changes) elements to control the balancing of
gasification reaction occurring to result in negligible tar
formation in resultant syngas products and waste products. Control
strategies discussed herein have been developed to manage a
variation in solar energy due to changes in solar energy and a
cyclic operating state.
[0090] In some embodiments, a material making up the reactor tubes
can possess high emissivity such as 0.7 emissivity coefficient or
better, high thermal conductivity such as 30 watts per meter-Kelvin
or better, at least moderate heat capacity of 8 joules per
mole-degree Kelvin or better. The material can also be resistant to
the oxidizing air environment in the receiver cavity and the
reducing environment of the biomass gasification reaction inside
the tubes in order to support operating temperatures within the
tubes in the tar-cracking regime above 1000.degree. C. This
operating temperatures eliminates any need for tar cracking
equipment downstream of the chemical reactor, and where in addition
operation at the high operating temperature improves heat transfer,
eliminates methane from the exit gases, decreases required
residence time of the biomass particles to achieve gasification,
which in turn decreases the physical size of the solar chemical
reactor.
[0091] FIG. 8 illustrates a flow diagram. In step 900, biomass
grinding can occur. Equipment generally used for grinding biomass
includes impact mills (e.g. hammer mills), attrition mills, and
kinetic disintegration mills (e.g. flail mills). A hammer mill
system can be used to grind the bales (loaded by conveyer) into
primary particles, which are to be fed into the solar thermal
gasifier. The re-ground particles have an average size between 500
.mu.m and 1000 .mu.m, and are loaded into the lock hopper system
with a standard belt conveyer.
[0092] In step 902 biomass feeding occurs. In some embodiments,
high pressure feeding may be used. High pressure feeding of solids
of biomass with gasification at pressure may reduce capital cost
due to the ability to use smaller compressors in some such systems.
Additionally, operating cost may be reduced because energy for
pressurizing carrier gas comes from the sun, as opposed to from
electricity. The lock hopper system can feed the reactor processes
at pressure. For example, the feeding system can entrain the
biomass materials in steam at high pressure, successfully disengage
the particulates in the cyclone system, and distribute flow
appropriately to the reactor tubes.
[0093] In step 904 gasification occurs. For example, in some
embodiments, concentrated solar thermal energy drives gasification
of the particles of the biomass to generate at least hydrogen and
carbon monoxide products from the gasification reaction.
[0094] In step 906 fuel synthesis occurs. An on-site fuel synthesis
reactor can receive the hydrogen and carbon monoxide products from
the gasification reaction and use the hydrogen and carbon monoxide
products in a hydrocarbon fuel synthesis process to create a liquid
hydrocarbon fuel. The fuel synthesis reactor may be geographically
located on the same site as the chemical reactor and integrated
into the process to utilize the hydrogen and carbon monoxide
products from the gasification reaction.
[0095] Some embodiments of the solar-driven bio-refinery include
one or more spray nozzles to supply water to the product gas
exiting the chemical reactor to shift some of the product carbon
monoxide to additional hydrogen and carbon dioxide gas in a water
gas shift reaction. The reaction is designed to make the hydrogen
to carbon monoxide ratio appropriate for methanol synthesis, such
as a H2:CO ratio in the synthesis gas within the range 2.0 to
2.7.
[0096] An insulation layer around the receiver can include
resistance heaters connected to the outer wall of the receiver to
assist with maintaining temperature in the 800-1600 degree C.
range. Waste heat from a quenching unit quenching the gasification
products heats high temperature storage material in hot beds in an
exit of the receiver. The waste heat is used with a material or
working fluid, e.g. molten salts, for use in electrical power
generation to supply a source of power for including at least the
resistance heaters. The control system can turn on and off the
resistance heaters as additional heat sources for maintaining
temperature as need be. The control system supplies a control
signal to the feed system, the solar energy concentrating fields,
the supplemental resistance heating system and potentially to a
recirculation system. The lag times and response times of the: 1)
heliostat field to alter alignment and an amount of concentrated
solar energy supplied, 2) feed system to alter an amount of biomass
flowing in the reactor tubes, 3) time for weather events to alter
an amount of solar energy available, such as 30 seconds for a
passing cloud, are factors taken into account by a control
algorithm in the computerized control system in sending out the
control signals to the feed system, the solar energy concentrating
fields, and the supplemental resistance heating system.
[0097] Some embodiments relate to reactor control, receiver
control, control of the flux profile, etc. Such systems and methods
may include adapting tubes/reactor per the flux profile to take
advantage of variations in solar flux in the profile, modifying
parameters to control flux across aperture, and shaping incident
radiation.
[0098] An example solar-driven chemical reactor system can include
a solar thermal receiver aligned to absorb concentrated solar
energy from one or more solar energy concentrating fields. These
fields can include an array of heliostats, solar concentrating
dishes, or any combination of the two. Additionally, a solar driven
chemical reactor may be used. The reactor can have multiple reactor
tubes located inside the solar thermal receiver, where in the
multiple reactor tubes an endothermic chemical reaction driven by
radiant heat occurs. The multiple reactor tubes in this reactor
design may increase available reactor surface area for radiative
exchange to the reactants as well as creates an inter-tube
radiation exchange. Additionally, the endothermic chemical reaction
includes one of the following biomass gasification, steam methane
reforming, methane cracking, steam ethane cracking to produce
ethylene, metals refining, carbon dioxide capture and other similar
endothermic carbon-based chemical reactions can be conducted in
this reactor using solar thermal energy.
[0099] In some embodiments, a first solar energy concentrating
field can be a non-uniform heliostat field with a staggered height
of the heliostats. Where a farther away a row of heliostat is from
the receiver, then the height of the heliostats in that row is
increased and also a spacing between heliostat rows is increased as
the row of heliostat moves away in distance from the solar thermal
receiver. The non-uniform heliostat field is used to generate the
concentrated solar energy at greater than or equal to 500 sun
concentrations with a secondary concentrator or 1,000 sun
concentrations with no secondary concentrator focused at the
apertures or windows of the receiver for the solar driven chemical
reactor.
[0100] The solar-driven chemical reactor system can include a
non-uniform heliostat field has >25,000 m.sup.2 of reflecting
surface, >50,000 m.sup.2 of reflecting surface, or >100,000
m.sup.2 of reflecting surface, that cooperates with the solar
thermal receiver to have an ability to control an amount of solar
energy flux across the apertures or windows. A heliostat field with
other total reflective surfaces areas may also be used.
[0101] The reflecting surface cooperates with the solar thermal
receiver to have an ability to control an amount of solar energy
flux across the apertures or windows that is applied to reactor
tubes and cavity walls to allow enough energy from a radiant energy
to raise the heat inside the tubes. This increase in the heat may
initiate and sustain a sufficiently high temperature so that
gasification occurs of greater than 90 percent of the biomass
particles into reactant products. The reactant products can include
hydrogen and carbon monoxide gas in the very short residence time
between the range of 0.01 and 5 seconds and a preferred range of
0.01 to 2 seconds. The size and a shape of the one or more
apertures or windows can determined by the heliostat field trying
to focus into the apertures or windows a total amount of light in
sun concentrations that is needed for the short residence times
balanced against an efficiency of a solar energy being concentrated
from the non-uniform heliostat field.
[0102] The methods and apparatuses of the invention in some cases
may be implemented using computer software. If written in a
programming language conforming to a recognized standard, sequences
of instructions designed to implement the methods can be compiled
for execution on a variety of hardware platforms and for interface
to a variety of operating systems. It will be appreciated that a
variety of programming languages may be used to implement the
teachings of the invention as described herein. Furthermore, it is
common in the art to speak of software, in one form or another
(e.g., program, procedure, application, driver, etc.), as taking an
action or causing a result. Such expressions are merely a shorthand
way of saying that execution of the software by a computer causes
the processor of the computer to perform an action or produce a
result.
[0103] A machine-readable medium is understood to include any
mechanism for storing or transmitting information in a form
readable by a machine (e.g., a computer). For example, a
machine-readable medium includes read only memory (ROM); random
access memory (RAM); magnetic disk storage media; optical storage
media; flash memory devices, etc.
[0104] While some specific embodiments of the invention have been
shown the invention is not to be limited to these embodiments. The
invention is to be understood as not limited by the specific
embodiments described herein, but only by scope of the appended
claims.
* * * * *