U.S. patent application number 11/725048 was filed with the patent office on 2007-10-04 for production of synthetic transportation fuels from carbonaceous materials using self-sustained hydro-gasification.
This patent application is currently assigned to The Regents of the University of California. Invention is credited to Colin E. Hackett, James E. Heumann, Uy Q. Ngo, Joseph N. Norbeck, Nguyen T. Tran, Bilge Yilmaz.
Application Number | 20070227069 11/725048 |
Document ID | / |
Family ID | 27734515 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070227069 |
Kind Code |
A1 |
Norbeck; Joseph N. ; et
al. |
October 4, 2007 |
Production of synthetic transportation fuels from carbonaceous
materials using self-sustained hydro-gasification
Abstract
A process and apparatus for producing a synthesis gas for use as
a gaseous fuel or as feed into a fischer-Tropsch reactor to produce
a liquid fuel in a substantially self-sustaining process. A slurry
of particles of carbonaceous material in water, and hydrogen from
an internal source, are fed into a hydro-gasification reactor under
conditions whereby methane rich producer gases are generated and
fed into a steam pyrolytic reformer under conditions whereby
synthesis gas comprising hydrogen and carbon monoxide are
generated. A portion of the hydrogen generated by the steam
pyrolytic reformer is fed through a hydrogen purification filter
into the hydro-gasification reactor, the hydrogen therefrom
constituting the hydrogen from an internal source. The remaining
synthesis gas generated by the steam pyrolytic reformer is either
used as fuel for a gaseous fueled engine to produce electricity
and/or process heat or is fed into a Fischer-Tropsch reactor under
conditions whereby a liquid fuel is produced. Molten salt loops are
used to transfer heat from the hydro-gasification reactor, and
Fischer-Tropsch reactor if liquid fuel is produced, to the steam
generator and the steam pyrolytic reformer.
Inventors: |
Norbeck; Joseph N.;
(Riverside, CA) ; Hackett; Colin E.; (Riverside,
CA) ; Heumann; James E.; (Ridgecrest, CA) ;
Ngo; Uy Q.; (El Cajon, CA) ; Tran; Nguyen T.;
(Westminster, CA) ; Yilmaz; Bilge; (Arlington,
MA) |
Correspondence
Address: |
Robert Berliner;BERLINER & ASSOCIATES
Thirty-First Floor
555 West Fifth Street
Los Angeles
CA
90013
US
|
Assignee: |
The Regents of the University of
California
|
Family ID: |
27734515 |
Appl. No.: |
11/725048 |
Filed: |
March 16, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10503435 |
Jun 28, 2005 |
7208530 |
|
|
PCT/US03/03489 |
Feb 4, 2003 |
|
|
|
11725048 |
Mar 16, 2007 |
|
|
|
60355405 |
Feb 5, 2002 |
|
|
|
Current U.S.
Class: |
48/89 ;
422/198 |
Current CPC
Class: |
C10J 2300/0903 20130101;
C10J 2300/0973 20130101; C01B 2203/1258 20130101; C10J 2300/0943
20130101; C10J 2300/1659 20130101; C10J 3/723 20130101; Y02E 50/30
20130101; C01B 2203/0827 20130101; C01B 2203/1205 20130101; C10J
2300/0966 20130101; C10J 2300/165 20130101; C01B 2203/0495
20130101; C10G 2/32 20130101; C10J 3/00 20130101; C10J 3/66
20130101; C10J 2300/0916 20130101; C01B 2203/06 20130101; C10J
3/721 20130101; C01B 2203/1276 20130101; C10G 1/002 20130101; Y02P
20/52 20151101; C01B 2203/062 20130101; C01B 2203/0833 20130101;
C10G 2/30 20130101; C10J 2300/06 20130101; C10J 2300/0983 20130101;
C10J 2300/1807 20130101; Y02E 20/16 20130101; C01B 2203/04
20130101; Y02E 50/32 20130101; C10J 2300/1884 20130101; C01B
2203/00 20130101; C01B 2203/0894 20130101; C10J 2300/0946 20130101;
C01B 2203/0233 20130101; C10J 2300/0906 20130101; C10J 2300/1853
20130101; C10J 2300/1892 20130101; C01B 3/34 20130101; C01B
2203/0838 20130101; C01B 2203/0883 20130101; C01B 2203/146
20130101; C10J 2300/1253 20130101; C10J 3/54 20130101; C10J
2300/093 20130101; C10J 2300/1675 20130101; C10J 2300/092 20130101;
C10J 2300/0976 20130101; C10J 2300/0909 20130101; Y02P 20/145
20151101; C01B 2203/84 20130101; C10J 2300/1671 20130101; C01B
2203/148 20130101; C10J 2300/1693 20130101 |
Class at
Publication: |
048/089 ;
422/198 |
International
Class: |
B01J 8/00 20060101
B01J008/00; B01J 8/08 20060101 B01J008/08 |
Claims
1-21. (canceled)
22. Apparatus for producing a synthesis gas for use as a gaseous
fuel or as feed into Fischer-Tropsch reactor to produce a liquid
fuel, comprising: a source of carbonaceous material and water; a
hydro-gasification reactor; and a steam pyrolytic reformer; piping
connecting said source of carbonaceous material and water to the
hydro-gasification reactor for feeding carbonaceous material and
water thereto to generate methane and carbon monoxide; piping
connecting the hydro-gasification reactor to the steam pyrolytic
reformer for feeding methane rich producer gases generated in the
hydro-gasification reactor to the steam pyrolytic reformer to
generate synthesis gas comprising hydrogen and carbon monoxide; and
piping connecting the steam pyrolytic reformer to the
hydro-gasification reactor for feeding a portion of the hydrogen
generated by the steam pyrolytic reformer into the
hydro-gasification reactor.
23. The apparatus of claim 22 including a hydrogen purification
filter through which said portion of hydrogen generated by the
steam pyrolytic reformer is obtained.
24. The apparatus of claim 22 including a grinder forming particles
of the carbonaceous material, a receptacle for the particles and
water to form a slurry of the carbonaceous particles, and piping
connecting the receptacle to the hydro-gasification reactor for
feeding the slurry thereto.
25. The apparatus of claim 24 including a steam generator to heat
the slurry of carbonaceous material with superheated steam, a steam
separator for separating the superheated steam from the slurry
prior to the slurry being fed into the hydro-gasification reactor,
and piping for feeding the separated steam into the steam pyrolytic
reformer to react with the methane rich producer gases from the
hydro-gasification reactor.
26. The apparatus of claim 24 including a steam generator to heat
the slurry of carbonaceous material with superheated steam whereby
the slurry and superheated steam can be fed into the
hydro-gasification reactor.
27. The apparatus of claim 26 including a Fischer-Tropsch reactor
and piping connecting the steam pyrolytic reformer to the
Fischer-Tropsch reactor for feeding the remainder of the synthesis
gas generated by the steam pyrolytic reformer into the
Fischer-Tropsch reactor to produce a liquid fuel.
28. The apparatus of claim 26 including molten salt loops to
transfer heat from one or both of the hydro-gasification reactor
and Fischer-Tropsch reactor to one or both of the steam generator
and the steam pyrolytic reformer.
29. The apparatus of claim 27 including molten salt loops to
transfer heat from the hydro-gasification reactor and
Fischer-Tropsch reactor to the steam generator and the steam
pyrolytic reformer.
30. Apparatus for producing a liquid fuel in a substantially
self-sustaining process, comprising: a source of carbonaceous
material and water; a hydro-gasification reactor; a steam pyrolytic
reformer; a hydrogen purification filter; a Fischer-Tropsch
reactor; a grinder forming particles of the carbonaceous material;
a receptacle for the particles and water to form a slurry of the
carbonaceous particles; a steam generator to heat the slurry and
activate the carbon by pyrolysis with superheated steam; piping
connecting the steam separator to the hydro-gasification reactor
for feeding the slurry and superheated steam thereto to generate
methane and carbon monoxide; piping connecting the
hydro-gasification reactor to the steam pyrolytic reformer for
feeding methane rich producer gases generated in the
hydro-gasification reactor to the steam pyrolytic reformer to form
a synthesis gas comprising hydrogen and carbon monoxide; piping
connecting the steam pyrolytic reformer to the hydro-gasification
reactor through the hydrogen purification filter for feeding a
portion of hydrogen generated by the steam pyrolytic reformer into
the hydro-gasification reactor; and piping connecting the steam
pyrolytic reformer to the Fischer-Tropsch reactor for feeding the
remainder of the synthesis gas generated by the steam pyrolytic
reformer into the Fischer-Tropsch reactor to produce a liquid
fuel.
31. The apparatus of claim 30 including molten salt loops to
transfer heat from one or both of the hydro-gasification reactor
and Fischer-Tropsch reactor to one or both of the steam generator
and the steam pyrolytic reformer.
32. The apparatus of claim 30 including molten salt loops to
transfer heat from the hydro-gasification reactor and
Fischer-Tropsch reactor to the steam generator and the steam
pyrolytic reformer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Provisional Patent
Application Ser. No. 60/355,405, filed Feb. 5, 2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The field of the invention is the synthesis of
transportation fuel from carbonaceous feed stocks.
[0004] 2. Description of Related Art
[0005] There is a need to identify new sources of chemical energy
and methods for its conversion into alternative transportation
fuels, driven by many concerns including environmental, health,
safety issues, and the inevitable future scarcity of
petroleum-based fuel supplies. The number of internal combustion
engine fueled vehicles worldwide continues to grow, particularly in
the midrange of developing countries. The worldwide vehicle
population outside the U.S., which mainly uses diesel fuel, is
growing faster than inside the U.S. This situation may change as
more fuel-efficient vehicles, using hybrid and/or diesel engine
technologies, are introduced to reduce both fuel consumption and
overall emissions. Since the resources for the production of
petroleum-based fuels are being depleted, dependency on petroleum
will become a major problem unless non-petroleum alternative fuels,
in particular clean-burning synthetic diesel fuels, are developed.
Moreover, normal combustion of petroleum-based fuels in
conventional engines can cause serious environmental pollution
unless strict methods of exhaust emission control are used. A clean
burning synthetic diesel fuel can help reduce the emissions from
diesel engines.
[0006] The production of clean-burning transportation fuels
requires either the reformulation of existing petroleum-based fuels
or the discovery of new methods for power production or fuel
synthesis from unused materials. There are many sources available,
derived from either renewable organic or waste carbonaceous
materials. Utilizing carbonaceous waste to produce synthetic fuels
is an economically viable method since the input feed stock is
already considered of little value, discarded as waste, and
disposal is often polluting.
[0007] Liquid transportation fuels have inherent advantages over
gaseous fuels, having higher energy densities than gaseous fuels at
the same pressure and temperature. Liquid fuels can be stored at
atmospheric or low pressures whereas to achieve liquid fuel energy
densities, a gaseous fuel would have to be stored in a tank on a
vehicle at high pressures that can be a safety concern in the case
of leaks or sudden rupture. The distribution of liquid fuels is
much easier than gaseous fuels, using simple pumps and pipelines.
The liquid fueling infrastructure of the existing transportation
sector ensures easy integration into the existing market of any
production of clean-burning synthetic liquid transportation
fuels.
[0008] The availability of clean-burning liquid transportation
fuels is a national priority. Producing synthesis gases cleanly and
efficiently from carbonaceous sources, that can be subjected to a
Fischer-Tropsch process to produce clean and valuable synthetic
gasoline and diesel fuels, will benefit both the transportation
sector and the health of society. Such a process allows for the
application of current state-of-art engine exhaust after-treatment
methods for NO.sub.x reduction, removal of toxic particulates
present in diesel engine exhaust, and the reduction of normal
combustion product pollutants, currently accomplished by catalysts
that are poisoned quickly by any sulfur present, as is the case in
ordinary stocks of petroleum derived diesel fuel, reducing the
catalyst efficiency. Typically, Fischer-Tropsch liquid fuels,
produced from biomass derived synthesis gases, are sulfur-free,
aromatic free, and in the case of synthetic diesel fuel have an
ultrahigh cetane value.
[0009] Biomass material is the most commonly processed carbonaceous
waste feed stock used to produce renewable fuels. Waste plastic,
rubber, manure, crop residues, forestry, tree and grass cuttings
and biosolids from waster water (sewage) treatment are also
candidate feed stocks for conversion processes. Biomass feed stocks
can be converted to produce electricity, heat, valuable chemicals
or fuels. California tops the nation in the use and development of
several biomass utilization technologies. Each year in California,
more than 45 million tons of municipal solid waste is discarded for
treatment by waste management facilities. Approximately half this
waste ends up in landfills. For example, in just the Riverside
County, Calif. area, it is estimated that about 4000 tons of waste
wood are disposed of per day. According to other estimates, over
100,000 tons of biomass per day are dumped into landfills in the
Riverside County collection area. This municipal waste comprises
about 30% waste paper or cardboard, 40% organic (green and food)
waste, and 30% combinations of wood, paper, plastic and metal
waste. The carbonaceous components of this waste material have
chemical energy that could be used to reduce the need for other
energy sources if it can be converted into a clean-burning fuel.
These waste sources of carbonaceous material are not the only
sources available. While many existing carbonaceous waste
materials, such as paper, can be sorted, reused and recycled, for
other materials, the waste producer would not need to pay a tipping
fee, if the waste were to be delivered directly to a conversion
facility. A tipping fee, presently at $30-$35 per ton, is usually
charged by the waste management agency to offset disposal costs.
Consequently not only can disposal costs be reduced by transporting
the waste to a waste-to-synthetic fuels processing plant, but
additional waste would be made available because of the lowered
cost of disposal.
[0010] The burning of wood in a wood stove is an example of using
biomass to produce heat energy. Unfortunately, the open burning the
biomass waste to obtain energy and heat is not a clean and
efficient method to utilize the calorific value. Today, many new
ways of utilizing carbonaceous waste are being discovered. For
example, one way is to produce synthetic liquid transportation
fuels, and another way is to produce energetic gases for conversion
into electricity.
[0011] Using fuels from renewable biomass sources can actually
decrease the net accumulation of greenhouse gases, such as carbon
dioxide, while providing clean, efficient energy for
transportation. One of the principal benefits of co-production of
synthetic liquid fuels from biomass sources is that it can provide
a storable transportation fuel while reducing the effects of
greenhouse gases contributing to global warming. In the future,
these co-production processes could provide clean-burning fuels for
a renewable fuel economy that could be sustained continuously.
[0012] A number of processes exist to convert coal and other
carbonaceous materials to clean-burning transportation fuels, but
they tend to be too expensive to compete on the market with
petroleum-based fuels, or they produce volatile fuels, such as
methanol and ethanol that have vapor pressure values too high for
use in high pollution areas, such as the Southern California
air-basin, without legislative exemption from clean air
regulations. An example of the latter process is the Hynol Methanol
Process, which uses hydro-gasification and steam reformer reactors
to synthesize methanol using a co-feed of solid carbonaceous
materials and natural gas, and which has a demonstrated carbon
conversion efficiency of >85% in bench-scale demonstrations.
[0013] The need to identify new resources and methods for the
production of transportation fuels requires not only investigating
improvements in ways to produce current petroleum-based fuels but
also research into new methods for the synthesis of functionally
equivalent alternative fuels obtained using resources and methods
that are not in use today. The production of synthetic liquid fuels
from carbonaceous materials such as waste organic materials is one
way to solve these problems. The utilization of carbonaceous waste
materials to produce synthetic fuels can be considered a feasible
method of obtaining new resources for fuel production since the
material feed stock is already considered a waste without value and
often it's disposal creates additional sources of environmental
pollution.
SUMMARY OF THE INVENTION
[0014] The present invention makes use of steam pyrolysis,
hydro-gasification and steam reformer reactors to produce a
synthesis gas that can be converted into a synthetic paraffinic
fuel, preferably a diesel fuel, although synthetic gasolines and
jet propulsion fuels can also be made, using a Fischer-Tropsch
paraffin fuel synthesis reactor. Alternatively, the synthesis gas
may be used in a co-generated power conversion and process heat
system. The present invention provides comprehensive equilibrium
thermo-chemical analyses for a general class of co-production
processes for the synthesis of clean-burning liquid transportation
fuels, thermal process energy and electric power generation from
feeds of coal, or other carbonaceous materials, and liquid water.
It enables a unique design, efficiency of operation and
comprehensive analysis of coal, or any other carbonaceous feed
materials to co-produced fuel, power and heat systems.
[0015] The invention provides a process and apparatus for producing
a synthesis gas for use as a gaseous fuel or as feed into a
Fischer-Tropsch reactor to produce a liquid paraffinic fuel,
recycled water and sensible heat, in a substantially
self-sustaining process. A slurry of particles of carbonaceous
material suspended in liquid water, and hydrogen from an internal
source, are fed into a steam generator for pyrolysis and
hydro-gasification reactor under conditions whereby super-heated
steam, methane, carbon dioxide and carbon monoxide are generated
and fed into a steam reformer under conditions whereby synthesis
gas comprising primarily of hydrogen and carbon monoxide are
generated. Using a hydrogen separation filter for purification, a
portion of the hydrogen generated by the steam reformer is fed into
the hydro-gasification reactor as the hydrogen from an internal
source. The remaining synthesis gas generated by the steam reformer
is either used as fuel for a gaseous fueled engine or gas turbine
to produce electricity and process heat, or is fed into a
Fischer-Tropsch fuel synthesis reactor under conditions to produce
a liquid fuel, and recycled water. The correct stoichiometric ratio
of hydrogen to carbon monoxide molecules fed into the
Fischer-Tropsch fuel synthesis reactor, is controlled by the water
to carbon ratio in the feed stocks. Molten salt loops are used to
transfer heat from the exothermic hydro-gasification reactor (and
from the exothermic Fischer-Tropsch reactor if liquid fuel is
produced) to the endothermic steam generator for pyrolysis and the
steam reformer reactor vessels.
[0016] In particular, the present invention provides the following
features.
[0017] 1) A general purpose solid carbonaceous material feed system
that can accept arbitrary combinations of coal, urban and
agricultural biomass, and municipal solid waste for
hydro-gasification.
[0018] 2) A first stage, steam generator for pyrolysis and
hydro-gasification unit.
[0019] 3) A steam reformer as a second stage reactor to produce
hydrogen rich synthesis gas from the output of the first stage
steam generator for pyrolysis and hydro-gasification unit. The
molal steam to carbon ratio is maintained as necessary to bring the
chemical reactions close to equilibrium;
[0020] 4) Either (a) a Fischer-Tropsch (synthesis gas-to-liquid)
fuel synthesizer as a third and final stage reactor to convert the
synthesis gas from the steam reformer into a sulfur-free
clean-burning liquid transportation fuel, and recycled water or (b)
use of generated synthesis gas as fuel for process heat and/or in a
fuel engine or gas turbine that can generate electricity;
[0021] 5) Three thermo-chemical process reactors are operated to
produce nearly pure paraffinic hydrocarbon liquids (similar to
petroleum derived diesel fuels) and wax-like compounds (similar to
petroleum derived USP paraffinic jellies, which can be further
refined into more diesel-like fuels using conventional methods)
from carbonaceous feed stocks (such as waste wood) in a continuous
self-sustainable fashion without the need for additional fuels or
external energy sources. The reactor configurations can also be
optimized for the production of other synthetic fuels, such as
dimethyl ether (a fuel similar to propane, that can be used as a
transportation fuel in diesel engines and gas turbines) and gaseous
fuel grade hydrogen (a fuel that can be used in engines and
turbines, and if purified to remove carbon monoxide, as an
electrochemical fuel in a fuel cell), as well as energetic
synthesis gases for combined cycle power conversion and electric
power production.
[0022] The fundamental advantages of this invention, over what was
achievable with the prior art, are: (a) energy efficient (>85%)
methane production from the available carbon in the carbonaceous
feed stock using steam pyrolysis to activate the carbon and
hydrogen gas as the sole initiating reactant, in contradistinction
to partial oxidative gasification usually requiring an additional
energy intensive air separation system to provide the necessary
oxygen; (b) chemically self-sustained operation of the first stage
hydro-gasification reactor by feeding-back surplus hydrogen gas
produced in the second stage methane steam reformer reactor; (c)
energy efficient synthesis of clean-burning transportation fuels
using the effluent gases from the steam reformer, such as: (i)
paraffinic compounds using a third stage Fischer-Tropsch fuel
synthesis reactor, (ii) dimethyl ether synthesis using a third
stage synthesis reactor, and (iii) hydrogen production using a
hydrogen separation and/or purification filter without the need for
a third stage fuel synthesis reactor; (d) thermally self-sustained
operation of all reactors by effective management of thermal and
chemical energy using combinations of molten salt or water/steam
heat transfer fluids, combustion of product energetic gases to
start and maintain process temperatures, recovered process heat for
the generation of electric power, without the need for additional
fuels and external energy sources; (e) significantly reduced
airborne emissions from all enclosed processes reactors and/or
synthesis gas combustors when compared to direct naturally
aspirated combustion (usually known as open incineration) of the
carbonaceous feed materials; and f) the ability to capture all
gaseous carbon dioxide effluent from process reactors or
intra-process synthesis gas combustors for sequestration and/or
chemical conversion into condensed phase compounds using
conventional technologies.
[0023] These novel configurations of the process reactors have the
capability to improve the overall efficiency of energy utilization
for carbonaceous material conversion in a co-production plant for
synthetic fuels, chemicals and energy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a flow diagram showing the overall modeling of the
present invention;
[0025] FIG. 2 is a graph showing a plot of carbon conversion vs.
H.sub.2/C and H.sub.2O/C ratios at 800.degree. C. and 30 atm. in
HPR;
[0026] FIG. 3 is a graph showing a plot of CH.sub.4/C feed ratio
vs. H.sub.2/C and H.sub.2O/C ratios at 800.degree. C. and 30 atm.
in HPR;
[0027] FIG. 4 is a graph showing a plot of CO.sub.2/C feed ratio
vs. H.sub.2/C and H.sub.2O/C ratio sat 800.degree. C. and 30 atm.
in HPR;
[0028] FIG. 5 is a graph showing a plot of CO/C feed ratio vs.
H.sub.2/C and H.sub.2O/C ratios at 800.degree. C. and 30 atm. in
HPR;
[0029] FIG. 6 is a graph showing the effects of Temperature and
Pressure conditions on CO.sub.2/H ration the hydro-gasifier reactor
(HGR) at fixed feed of 2.629 moles of H.sub.2 and 0.0657 moles of
H.sub.2O per mole of C;
[0030] FIG. 7 is a graph showing the effect of Temperature and
Pressure conditions on CH.sub.4/H ratio in the HGR at fixed feed of
2.629 moles of H.sub.2 and 0.0657 moles of H.sub.2O per mole of
C;
[0031] FIG. 8 is a graph showing the effect of Temperature and
Pressure conditions on H.sub.2/C ratio in the HGR at fixed feed of
2.629 moles of H.sub.2 and 0.0657 moles of H.sub.2O per mole of
C;
[0032] FIG. 9 is a graph showing the effect of Temperature and
Pressure conditions on CO/H in the HGR at fixed feed of 2.629 moles
of H.sub.2 and 0.0657moles of H.sub.2O per mole of C;
[0033] FIG. 10 is a graph showing the effect of input H.sub.2O/C
ratio on steam reformer (SPR) performance measure by the net H2/CO
ratio after H2 recycling for the HGR at 1000.degree. C. and 30
atm;
[0034] FIG. 11 is a graph showing the effect of changing the input
H.sub.2O/C ratio on SPR products, CO, CO.sub.2 and CH.sub.4 in the
SPR at 1000.degree. C. and 30 atm;
[0035] FIG. 12 is a graph showing the effect of Temperature and
Pressure conditions on H.sub.2/CO ratio in the SPR (2.76 moles of
H.sub.2O/mole of C added to the SPR);
[0036] FIG. 13 is a graph showing the effect of Temperature and
Pressure conditions on CH.sub.4/C ratio in the SPR (2.76 moles of
H.sub.2O/mole of C added to the SPR);
[0037] FIG. 14 is a diagram showing the Mass Flow Schematic of
Biomass Hydro-gasification for production of Fischer-Tropsch
paraffin fuels;
[0038] FIG. 15 is a diagram showing the Molal Flow Schematic of
Biomass Hydro-gasification for production of Fischer-Tropsch
paraffin fuels;
[0039] FIG. 16 is a diagram showing the Thermal Energy Management
Schematic of Biomass Hydro-gasification for production of
Fischer-Tropsch paraffin fuels;
[0040] FIG. 17 is a diagram showing the Water/Steam Flow Schematic
of Biomass Hydro-gasification for production of Fischer-Tropsch
paraffin fuels;
[0041] FIG. 18 is a diagram showing Molten Salt Flow Schematic of
Biomass Hydro-gasification for production of Fischer-Tropsch
paraffin fuels;
[0042] FIG. 19 is a diagram showing Mass Flow Schematic of Biomass
Hydro-gasification for production of dimethyl ether;
[0043] FIG. 20 is a diagram showing Mole Flow Schematic of Biomass
Hydro-gasification for production of dimethyl ether;
[0044] FIG. 21 is a diagram showing Thermal Energy Management
Schemitic of Biomass Hydro-gasification for production of dimethyl
ether;
[0045] FIG. 22 is a diagram showing Water/Steam Flow Schematic of
Biomass Hydro-gasification for production of dimethyl ether;
[0046] FIG. 23 is a diagram showing Molten Salt Flow Schematic of
Biomass Hydro-gasification for production of dimethyl ether;
[0047] FIG. 24 is a diagram showing Mass Flow Schematic of Biomass
Hydro-gasification for production of gaseous hydrogen fuel;
[0048] FIG. 25 is a diagram showing Mole Flow Schematic of Biomass
Hydro-gasification for production of gaseous hydrogen fuel;
[0049] FIG. 26 is a diagram showing Thermal Energy Management
Schematic of Biomass Hydro-gasification for production of gaseous
hydrogen fuel;
[0050] FIG. 27 is a diagram showing Water/Steam Flow Schematic of
Biomass Hydro-gasification for production of gaseous hydrogen
fuel;
[0051] FIG. 28 is a diagram showing Molten Salt Flow Schematic of
Biomass Hydro-gasification for production of gaseous hydrogen
fuel;
[0052] FIG. 29 is a diagram showing Mass Flow Schematic of Biomass
Hydro-gasification for production of electricity;
[0053] FIG. 30 is a diagram showing Mole Flow Schematic of Biomass
Hydro-gasification for production of electricity;
[0054] FIG. 31 is a diagram showing Thermal energy Management
Schematic of Biomass Hydro-gasification for-production of
electricity;
[0055] FIG. 32 is a diagram showing Water/Steam Flow Schematic of
Biomass Hydro-gasification for production of electricity;
[0056] FIG. 33 is a diagram showing Molten Salt Flow Schematic of
Biomass Hydro-gasification for production of electricity;
[0057] FIG. 34 is a mass flow schematic of biomass
hydro-gasification for Fischer-Tropsch paraffin fuel production
using an adiabatic HGR and a 9:1 water feed;
[0058] FIG. 35 is a molal flow schematic of biomass
hydro-gasification for Fischer-Tropsch paraffin fuel production
using an adiabatic HGR and a 9:1 water feed;
[0059] FIG. 36 is a thermal energy management schematic of biomass
hydro-gasification for Fischer-Tropsch paraffin fuel production
using an adiabatic HGR and a 9:1 water feed;
[0060] FIG. 37 is a water/steam flow schematic of biomass
hydro-gasification for Fischer-Tropsch paraffin fuel production
using an adiabatic HGR and a 9:1 water feed;
[0061] FIG. 38 is a molten salt flow schematic of biomass
hydro-gasification for Fischer-Tropsch paraffin fuel production
using an adiabatic HGR and a 9:1 water feed.
DETAILED DESCRIPTION OF THE INVENTION
[0062] A steam generator for pyrolysis, hydro-gasification reactor
(HGR) and steam pyrolytic reformer (SPR) (also called a steam
pyrolytic reactor, steam reformer or steam reactor) such as used in
a Hynol process, may be utilized to produce the synthesis gas
(syngas) through steam pyrolysis of the feed stock,
hydro-gasification and steam reforming reactions. The reactions
start in the HGR to convert carbon in the carbonaceous matter into
a methane rich producer gas and continue through the SPR to produce
synthesis gas with the correct hydrogen and carbon monoxide
stiochiometry for efficient operation of the Fischer-Tropsch
process. With the Fischer-Tropsch process as the final step in
processing, products such as synthetic gasoline, synthetic diesel
fuel and recycled water can be produced.
[0063] The feedstock requirement is highly flexible. Many feeds
that consist of different carbonaceous materials can be wet milled
to form a water slurry that can be fed at high pressure into a
steam pyrolyzer, hydro-gasifier and steam reformer reactors for
synthesis gas production. The feed to water mass ratio can even
vary during the running of the process, with a knowledge of the
chemical content of the feed, to maintain the carbon-hydrogen
stiochiometry required for an optimized fuel synthesis process.
Appropriate carbornaceous materials include biomass, natural gas,
oil, petroleum coke, coal, petrochemical and refinery by-products
and wastes, plastics, tires, sewage sludge and other organic
wastes. For example, wood is an example of waste biomass material
that is readily available in Riverside County, Calif. This
particular waste stream could be augmented with other carbonaceous
materials, such as green waste and biosolids from water treatment
that are available in Riverside County, and would otherwise go to
landfill.
[0064] When used to make a transportation fuel, such as diesel
fuel, the process is designed so that the feedstock makes the
maximum amount of Fischer-Tropsch paraffinic product required. The
desired output consists of a
[0065] The thermo-chemical conversion of carbonaceous materials
occurs by two main processes: hydro-gasification and steam
reformation, with steam pyrolysis of the feedstock occurring within
the steam generator to pre-treat feedstock and activate the carbon
contained therein. The hydro-gasifier requires an input of the
pyrolyzed carbonaceous waste, hydrogen, steam, reacting in a vessel
at high temperature and pressure, which in a specific
implementation is approximately 30 atmospheres and 1000 degrees
Celsius. Steam reforming of the methane rich effluent gas from the
HGR also requires an approximate pressure of 30 atmospheres and
1000 degrees Celsius. More generally, each process can be conducted
over a temperature range of about 700 to 1200 degrees Celsius and a
pressure of about 20 to 50 atmospheres. Lower temperatures and
pressures can produce useful reaction rates with the use of
appropriate reaction catalysts.
[0066] Referring to FIG. 1, which is an overall flow diagram, the
order of general processes that carry out these main reaction
processes is shown (specific amounts for a particular embodiment
are in the flow diagrams shown in FIGS. 14 through 38). Piping is
used to convey the materials through the process. The feed 11 is
chopped, milled or ground in a grinder 10 into small particles,
mixed with the recycled water 12 and placed in a receptacle or tank
14 as a liquid, suspension slurry 16 that is transportable as a
compressed fluid by a pump 18 to a steam generator 20 where the
slurry 16 is superheated and pyrolyzed, followed by either
separation of the steam in a steam separator 22 so that steam goes
through piping 24 that is separate from piping that delivers the
pumped, dense slurry paste 26, or a direct steam pyrolysis feed
through piping 27.
[0067] The dense slurry paste feed 26, or the direct steam
pyrolysis feed 27, enters the HGR 28. Hydrogen from an internal
source (from the steam reformer via a hydrogen separation filter
described below) and a fraction of the previously produced steam
flow into the HGR 28 for the desired output. The output gases
consists largely of methane, hydrogen, carbon monoxide, and
super-heated steam. The gases produced by the HGR 28 leaves the
liquid hydrocarbon, such as cetane, C.sub.16H.sub.34, within the
carbon number range, 12 to 20, suitable as a diesel fuel. Excess
synthesis gas output from the SPR, i.e., "leftover" chemical energy
from the Fischer Tropsch synthetic fuel producing process, can be
used as an energetic fuel to run a gas turbine for electricity
production. The synthesis gas output after recycling enough
hydrogen to sustain the hydro-gasifier, may be used for this
purpose also, depending on the needs of the user. The following
provides a method for maximizing the economic potential from the
present invention in the conversion of carbonaceous materials to a
usable transportation fuels and inclusive of the possibility for
direct electric power production through a gas turbine combined
cycle.
[0068] 1) Find approximate data on available carbonaceous wastes,
their chemical composition and perform further analysis on the
practical need for the process.
[0069] 2) Model the important reactions within the process
consisting of the steam generator for pyrolysis, hydro-gasifier,
steam reformer, and the Fischer-Tropsch (or other fuel synthesis)
reactor on a continuous flow-through basis. This may be done by
optimizing the Fischer-Tropsch (or other fuel synthesizer)
feedstock for the optimum stoichiometric hydrogen to carbon
monoxide mole ratio for fuel to be synthesized.
[0070] 3) Perform an economic analysis on the costs to obtain and
prepare the input material required, capital costs, operating and
maintenance, and product yield and costs.
[0071] Specific implementations are given below in conjunction with
flow charts provided in the Figures, demonstrating the conversion
of waste wood, as the candidate carbonaceous material, to a liquid
diesel transportation fuel, recycled water and an alternative power
source, via a Fischer-Tropsch process linked to a gas turbine
combined cycle. chamber and is pumped over to the SPR 30. The
un-reacted residue (or ash) from the HGR, is periodically removed
from the bottom of the reactor vessel using a double buffered
lock-hopper arrangement, that is commonly used in comparable high
pressure gasification systems. The ash is expected to be comprised
of sand, SiO.sub.2, and alumina, Al.sub.2O.sub.3, with trace
amounts of metals. The input to the SPR 30 is delivered from either
the steam separator 22 by piping 32 through a heater 34 and further
piping 36, or via the HGR 28 output piping, to provide
greater-than-theoretical steam to carbon ratio into the SPR 30, to
mitigate coking in the reactor. The output is a higher amount of
hydrogen, and CO, with the appropriate stiochiometry for the
desired hydrocarbon fuel synthesis process described below.
[0072] The output of the SPR 30 is directed via piping 38 through
heat exchangers 40 and 42. Condensed water 44 is separated and
removed from the SPR output, via a heat exchanger and liquid water
expander 47. The non-condensable gaseous output of SPR 30 is then
conveyed to a hydrogen separation filter 46. A portion of the
hydrogen from the SPR output, about one-half in this embodiment, is
carried from the filter 46, passed through the heat exchanger 40
with a resultant rise in its temperature (in the embodiment from
220 degrees centigrade to 970 degrees Centigrade) and delivered to
the HGR 28 as its hydrogen input. The hot effluent from the SPR
output is cooled by passing through heat exchangers 40 and 42, used
to heat the recycled hydrogen, and make steam respectively. The
condensed water 44 leaving the heat exchanger 47 is recycled back
to make the water supply 12 for the slurry feed. By such means, a
self-sustaining process is obtained.
[0073] The fuel synthesis gas is then used for one of two options.
Based on the calorific value, the synthesis gas may go through a
gas turbine combined cycle for direct energy production or through
a fuel synthesis reactor (in this embodiment, a Fischer-Tropsch
process to produce a clean diesel fuel and recycled water). In
accordance with a specific embodiment of the invention, the
synthesis gas is directed through an expansion turbine 48, to
recover mechanical energy by lowering the pressure of the gaseous
feed into the Fischer-Tropsch reactor 50. The mechanical power
produced by the liquid state turbine, the Brayton and Rankine cycle
turbines can be used to provide power for internal slurry, water
feed pumps, air compressor, with the surplus exported via
electricity generation, see Tables 1 through 7.
[0074] Efficiency may be maximized by adjusting input and process
parameters. The biomass/coal varying-mixture feed is synthesized
into a slurry by adding water whereby after steam separation the
carbon to hydrogen ratio will be appropriate for the process. A
slurry feed needs enough water to run the hydro-gasifier, the steam
reformer, and to keep the feed in a viable slurry after steam
separation. Prior art attempts at biomass conversion using solid
dry feed had many mechanical problems of feeding a solid into the
high pressure, and high temperature HGR reaction chamber. This
method of slurry feed has already been demonstrated and studied,
according to the results for the "Hydrothermal Treatment of
Municipal Solid Waste to Form High Solids Slurries in a Pilot Scale
System", by C. B. Thorsness et al., UCRL-ID 119685, published by
Lawrence Livermore Nation Laboratory, Livermore, Calif. in 1995. In
addition, there is related art published on the making and
operating of coal water slurry feeds. For example, see Z. Aktas et
al., Fuel Processing Technology 62 2000 1-15. The principle
reactions of the two main processes, hydro-gasification and steam
reforming, are shown here. The HGR independent reactions can be
expressed as: C+2H.sub.2.fwdarw.CH.sub.4 (1)
C+2H.sub.2O.fwdarw.CO+H.sub.2 (2)
CO.sub.2+H.sub.2.fwdarw.CO+H.sub.2O (3)
[0075] Reactions 2 and 3 are endothermic. Reaction 1 is
sufficiently exothermic to provide the heat of reaction for
reactions 2 and 3. Some preheating of the HGR will be needed to
bring the reactor up to its operating temperature. Thus, the HGR is
intended to be self-sustaining once the reactions have started and
achieve steady state.
[0076] The main purpose of the HGR process is to maximize the
carbon conversion from the feed stock into the energetic gases
CH.sub.4 and CO. After this process, hydrogen is produced by
reacting superheated steam with CH.sub.4 and CO within the SPR. In
the SPR, half the hydrogen is obtained from the superheated steam
and the remainder from the CH.sub.4. The principle reactions in the
SPR are considered to be: CH.sub.4+H.sub.2O.fwdarw.CO+3H.sub.2 (4)
CO.sub.2+H.sub.2.fwdarw.CO+H.sub.2O.fwdarw.CO.sub.2+H.sub.2 (5)
[0077] The steam reforming reactions (4 and 5) are often run with
steam concentrations higher than required for the stiochiometry
shown above. This is done to avoid coke formation and to improve
conversion efficiency. The required steam concentration is usually
specified in the form of the steam-to-carbon mole ratio (S:C), the
ratio of water steam molecules per carbon atom in the HGR feed. The
preferred (S:C) ratio for the SPR operation is greater than 3. This
steam rich condition favors the water-gas shift reaction. This
reaction is only slightly exothermic (.DELTA.H.degree.=-41 kJ/mole
CO); however, it produces additional hydrogen gas and converts
carbon monoxide into carbon dioxide. Unfortunately, an additional
unwanted secondary reaction can occur, the methanation reaction,
which consumes hydrogen: CO+3H.sub.2.fwdarw.CH.sub.4+H.sub.2O
(6)
[0078] The resulting effluent after the two main reactors is a
synthesis of gases rich in hydrogen, carbon monoxide, and steam.
Approximately half the hydrogen produced in the SPR is recycled
back to the HGR. Consequently, no outside source of hydrogen is
needed to maintain steady state operation.
[0079] The HGR and SPR processes, therefore, may be considered to
be chemically self-sustaining. The remaining synthesis gas is then
available for the production of fuels and process heat.
[0080] The present invention using the Fischer-Tropsch process can
produce a zero-sulfur, ultrahigh cetane value diesel-like fuel and
valuable paraffin wax products. The absence of sulfur enables low
pollutant and particle emitting diesel fuels to be realized.
[0081] The present invention also provides a source of by-products.
One useful by-product is purified water, which can be re-cycled to
create the slurry feed into the process. In a report by Rentech
titled "Fischer-Tropsch technology" dated 1998 see Rentech web
publications at hftp://)w.rentechinc.com. Rentech states that the
Fischer-Tropsch process with an iron catalyst makes about 7/10ths
of a barrel of water per barrel of Fischer-Tropsch products. A
cobalt catalyzed Fischer-Tropsch process makes about 1.1 to 1.3
barrels of water for each barrel of Fischer-Tropsch products, a
greater amount than iron. Part of the water may be recycled to make
steam in the steam reformer unit and for cooling in both the
synthesis gas and Fischer-Tropsch step of the overall process.
[0082] The Fischer-Tropsch reactions also produce tail gas that
contains hydrogen, CO, CO.sub.2, and some light hydrocarbon gases.
Hydrogen can be stripped out of the tail gas and recycled either to
the HGR or the Fischer-Tropsch reactor. Any small amounts of other
gases such as CO and CO2 may be flared off.
[0083] Two main products of Fischer-Tropsch may be characterized as
synthetic oil and petroleum wax. According to Rentech, in the above
report for their particular implementation of the Fischer-Tropsch
process, the mix of solid wax to liquid ratio is about 50/50.
Fischer-Tropsch products are totally free of sulfur, nitrogen,
nickel, vanadium, asphaltenes, and aromatics that are typically
found in crude oil. The products are almost exclusively paraffins
and olefins with very few, or no, complex cyclic hydrocarbons or
oxygenates that would otherwise require further separation and/or
processing in order to be usable end-products. The absence of
sulfur, nitrogen, and aromatics substantially reduces harmful
emissions.
[0084] California's Air Resources Board (CARB) specifications for
diesel fuel require a minimum cetane value of 48 and reduced sulfur
content. The above Rentech study with Shell diesel fuel produced
from a Fischer-Tropsch process has a cetane value of 76. The CARB
standard for sulfur in diesel fuel placed in the vehicle tank is
500 ppm by weight, and Shell's Fischer-Tropsch process diesel fuel
has no detectable amount in the ppm range. The CARB standard for
aromatic content is no more than 10% by volume (20% for small
refineries). The Shell Fischer-Tropsch process diesel fuel had no
detectable aromatics.
[0085] Rentech further affirmed through studies that the diesel
fuel may need no further processing because of the purity and
olefin products that may even be advantageous over crude oil
diesel. The Fischer-Tropsch diesel process is clean and the product
is cleaner, has a higher cetane value, and most likely does not
need further processing, when compared to a crude oil diesel.
[0086] A gas turbine combined cycle for electric power production
is an option. If the Fischer-Tropsch product is unexpectedly too
costly, the use of the synthesis gas heating value can be a viable
option, based on an overall efficiency of 65% of the synthesis gas
energy converting to electric energy. This number is reasonable
since the synthesis gas starts at a high temperature as opposed to
taking natural gas in from a pipeline.
[0087] Process modeling can be used to reasonably produce a
synthesis gas maximized for a yield high in CO and stoichiometric
hydrogen. First, the unit operation reactions of the
hydro-gasifier, steam reformer, and Fischer-Tropsch reactors are
modeled. This may be accomplished by using Stanjan, a DOS-based
computer program that uses equilibrium modeling. By varying the
parameters of temperature, pressure, original feedstock and gas
flows, a parameterization study was carried out based on costs and
output benefit. The hydro-gasifier variables were modified for the
maximum practical carbon conversion efficiency. The steam reformer
variables were modified for maximum practical CO output, enough
hydrogen for recycling output, and minimum CO.sub.2 production. The
study looked at the various parameters whereby two different values
varied for one constant, resulting in 3-D parameterization studies.
The following discusses the results from the computer modeling of
the main reactions using Stanjan programming.
[0088] Referring to FIG. 2, the effect of varying the water or
steam and hydrogen ratios on the conversion efficiency of carbon in
feedstock in the HGR is shown at 800.degree. C. and 30 atm. As the
hydrogen and water input to the HGR increases, the conversion
efficiency of carbon in feedstock increases until it reaches 100%.
The condition that falls in the area of 100% conversion efficiency
achieves one of the modeling objectives, and these conditions were
used. In order to avoid the cost of recycling of H.sub.2, the
minimum amount of H.sub.2 recycled to the HGR must be chosen. FIG.
3 shows the effect of H.sub.2 and H.sub.2O on CH.sub.4 in the HGR
at 800.degree. C. and 30 atm. FIG. 4 shows the effect of H.sub.2
and H.sub.2O on CO.sub.2 in the HGR at 800.degree. C. and 30 atm.
At a high amount of H.sub.2 and low amount of H.sub.2O input, the
amount of CO.sub.2 is low. Although the objective is to minimize
the amount of CO.sub.2 in the synthesis gas, it is not necessary to
minimize CO.sub.2 in the HGR because CO.sub.2 is gauged in the SPR
reactions through the water-gas-shift reaction to obtain a proper
ratio of H.sub.2 and CO for a maximum Fischer-Tropsch diesel
fraction. FIG. 5 shows the effect of H.sub.2 and H.sub.2O on CO in
the HGR at 800.degree. C. and 30 atm.
[0089] FIGS. 6, 7, 8 and 9 show the effects of varying temperature
and pressure on the chemical composition of the effluent gases from
the HGR at feed of 2.76 mol H.sub.2 and 0.066 mol H.sub.2O per mole
C in the feed stock. At these conditions of H.sub.2 and H.sub.2O
input to the HGR, the carbon conversion efficiency is estimated to
close to 100% in a temperature range of 800 to 1000.degree. C. and
a pressure range of 30 atm. to 50 atm, for equilibrium
chemistry.
[0090] FIG. 10 shows the ratio of H.sub.2 and CO available for feed
into the Fischer-Tropsch fuel synthesis reactor, against the steam
content added to the SPR at 800.degree. C. and 30 atm. This ratio
increases with the increasing amount of steam added to the SPR and
reaches 2.1 at about 3.94 mol steam (or water) added per mol C in
feedstock. With this amount of steam added, the system will achieve
chemical and thermal self-sustainability and provide a proper ratio
of H.sub.2 and CO for Fischer-Tropsch synthesis of cetane. FIG. 11
shows the effect of H.sub.2O added to the SPR at 800.degree. C. and
30 atm. FIGS. 12 and 13 show the effect of temperature and pressure
on the H.sub.2 and CO ratio and the conversion of CH.sub.4 in the
SPR. At higher temperature and lower pressure, this ratio is
higher. In a similar trend with the H.sub.2 and CO ratio, the
conversion of CH.sub.4 increases with increasing temperature and
with decreasing pressure. It is thus high temperature and low
pressure favored in the SPR.
[0091] The products of Fischer-Tropsch paraffinic liquid fuels are
in a wide range of carbon number. According to the above Rentech
report, about half of the products are diesel fuel. Also about half
of the products come in the form of wax, with minor amounts of
gases such as un-reacted reactants and hydrocarbon gases (methane,
ethane, propane and so forth). To exemplify the present invention,
cetane, which is in middle position of diesel range (C.sub.11 to
C.sub.20), was chosen as diesel fuel.
[0092] The results of thermo-chemical and thermodynamic modeling of
the hydro-gasified conversion of waste wood (biomass), as a
prototypical carbonaceous feed material, were used to examine the
details and illustrate the features of this invention. These
simulations of the novel sequence of process reactors were
undertaken to discover the thermo-chemical conditions needed to
achieve the production of synthetic fuels. For example, in the
production of synthetic diesel fuel, the objectives were to attain
self-sustained operation of the first stage hydro-gasifier. In a
particular embodiment, this is accomplished at an equilibrium
temperature of 1000.degree. C. (738.degree. C. when adiabatic) and
30 atmospheres pressure with a total hydrogen to carbon feed mole
ratio of at least 3.48:1 (1.67:1 when adiabatic), and water to
carbon feed ratio of at least 0.07:1 (0.43 when adiabatic), a water
steam to carbon feed mole ratio of at least 3.91:1 (1.67:1 when
adiabatic) into the second stage steam reforming reactor also
operating at an equilibrium temperature of 1000.degree. C.
(900.degree. C. when adiabatic) and 30 atmospheres pressure, to
obtain conditions for simultaneous optimal quantities of product
hydrogen for self-sustained operation of the first stage
hydro-gasification reactor and an adequate hydrogen to carbon mole
ratio of at least 2.1:1 in the residual synthesis gas stream to
feed the third stage Fischer-Tropsch reactor, operating at
200.degree. C. and 10 atmospheres pressure, and adiabatic
self-sustained operation of a special HGR and SPR combination
reactor, followed by a conventionally operated SPR and
Fischer-Tropsch reactors, with full thermal and chemical potential
energy management.
[0093] Tables 1 through 5 show the overall energy transfer rates
into and out from each heat exchanger and power conversion
component for each operating mode of the conversion process. The
mass flow, molal flow, thermal energy management, water/steam and
molten salt schematic diagrams for each of the five operating modes
of the conversion process are also shown as FIGS. 14-18, 19-23,
24-28, 29-33 and 34-38 respectively. Tables 6 and 7 summarize the
results of the performance studies and process configuration
parameters for each of the five operating modes of the conversion
process.
[0094] The carbonaceous material feed process initially described
above uses a water slurry suspension feed technology, originally
developed by Texaco for use in its partial-oxidation gasifiers,
that can accept a wide variety of carbonaceous materials, and can
be metered by controlled pumping into the first stage hydrogen
gasification reactor (HGR) to produce a methane rich gas with high
conversion efficiency (measured to have at least 85% carbon feed
chemical utilization efficiency). Enough heat is available to be
able to generate super-heated steam from the biomass-water slurry
feed to supply and operate the second stage steam-methane reformer.
The reformer product gas is fed into a hydrogen membrane filter
that allows almost pure hydrogen to pass back into the first stage
reactor to sustain the hydro-gasification of the biomass. The
remaining second stage product gas, not passing through the
hydrogen filter, is cooled to condense and re-cycle any water vapor
present back into the slurry carbonaceous feed system. The
unfiltered gas is fed into the fuel synthesis reactors, which
comprise a Fischer-Tropsch paraffin hydro-carbon synthesis reactor,
which operates at 200.degree. C. and 10 atmospheres pressure.
Process modeling reveals that the hydrogen/carbon molecular feed
ratio must be at least 2.1:1 to optimize production of chemically
pure and clean-burning [sulfur-free] diesel-like liquid fuels and
high value chemically pure paraffin-like waxes, without additional
fuel or energy. (FIGS. 14-18 and Tables 1, 6 and 7 or FIGS. 34-38
and Tables 5, 6 and 7 for adiabatic first stage reactor operation),
or a dimethyl ether synthesis reactor, which operates at
200.degree. C. and 70 atmospheres pressure. This reactor produces
approximately 92.4% DME and 7.1% methanol. The methanol is
combusted to co-generate about 30 MW of electricity and 20 MW of
process heat for exchange with the molten salt and water/steam heat
transfer loops (see FIGS. 19-23 and Tables 2, 6 and 7), hydrogen
gaseous fuel synthesis (see FIGS. 24-28 and Tables 3, 6 and 7), and
all electric power production without fuel synthesis (see FIGS.
29-33 and Table 4, 6 and 7).
[0095] Net export of electric power is possible in all five modes
of operation of the simulated biomass hydro-gasification process
plant. The results of these simulations are summarized in Table 6
and 7. The overall energy utilization goes from 50.7% (71.2% when
adiabatic) for Fischer-Tropsch synthesis to 67.2% for hydrogen
production. Optimized electric power production utilizes about
38.2% of the chemical potential energy in the biomass feed stock
for clean-burning power conversion. In general the process modes
could be switched using an appropriate proportional valve to
distribute the synthesis gas production after separation of enough
pure hydrogen gas for the first stage hydro-gasification
reactor.
[0096] The results of the overall modeling shown in FIG. 1 are
summarized as follows.
[0097] 1. Optimum conditions of the HGR: Operating at 1000.degree.
C. and 30 atm; 2.76 mol H.sub.2 per mol C in feedstock to maintain
self-sustainability; 0.066 mol H.sub.2O per mol C in feedstock.
[0098] 2. Optimum conditions of the SPR: Operating at 1000.degree.
C. and 30 atm; 4.022 mol H.sub.2O per mol C in feedstock.
[0099] 3. Fischer-Tropsch products: 0.199 ton wax per ton of
feedstock; 68.3 gallons of cetane (C.sub.16H.sub.34) diesel per ton
of feedstock.
[0100] Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the invention as defined by the
appended claims. Moreover, the scope of the present application is
not intended to be limited to the particular embodiments of the
process and apparatus described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present invention, processes and apparatuses,
presently existing or later to be developed that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present invention. Accordingly, the
appended claims are intended to include within their scope such
processes and apparatuses. TABLE-US-00001 TABLE 6 Summary of
Optimized Performance Studies for Biomass Conversion Options
##STR1## ##STR2## ##STR3## ##STR4## ##STR5## Notes No additional
energy or energetic feedstock is required for all conversion
options All rejected waste heat is at a temperature below 40 C. and
is not considered recoverable # DME stored as a compressed liquid
at 20 C., 5.1 atm. pressure, density 668 g/L and LHV 28.4 MJ/kg
[0101] TABLE-US-00002 TABLE 7 Summary of Optimized Performance
Parameters for Biomass Conversion Options* ##STR6## ##STR7##
##STR8## ##STR9## ##STR10## Notes No additional energy or energetic
feedstock is required for all conversion options All rejected waste
heal is at a temperature below 40 C. and is not considered
recoverable # DME stored as a compressed liquid at 20 C., 5.1 atm.
pressure, density 668 g/L and LHV 28.4 MJ/kg 1 bbl of compressed
liquid DME has a mass of 106.2 kg and LHV CPE of 3.02 GJ +Cubic
meters of liquified hydrogen (at 20 deg K) per day at 1 atm.
pressure Approximately 3.7 MJ/kg is needed to cool and liquify
hydrogen having an HHV of 144 MJ/kg *All thermochemical and
thermodynamic simulation data as of 10/1/2001
* * * * *