U.S. patent application number 11/879456 was filed with the patent office on 2008-01-24 for method for high energy density biomass-water slurry.
Invention is credited to Andres Aguirre, Joseph M. Norbeck, Chan Seung Park.
Application Number | 20080016752 11/879456 |
Document ID | / |
Family ID | 38957310 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080016752 |
Kind Code |
A1 |
Norbeck; Joseph M. ; et
al. |
January 24, 2008 |
Method for high energy density biomass-water slurry
Abstract
An energy efficient process for converting biomass into a higher
carbon content, high energy density slurry. Water and biomass are
mixed at a temperature and under a pressure that are much lower
than in prior processes, but under a non-oxidative gas, which
enables a stable slurry to be obtained containing up to 60% solids
by weight, 20-40% carbon by weight, in the slurry. The temperature
is nominally about 200.degree. C. under non-oxidative gas pressure
of about 150 psi, conditions that are substantially less stringent
than those required by the prior art.
Inventors: |
Norbeck; Joseph M.;
(Riverside, CA) ; Park; Chan Seung; (Placentia,
CA) ; Aguirre; Andres; (Highland, CA) |
Correspondence
Address: |
Robert Berliner;BERLINER & ASSOCIATES
Thirty-First Floor, 555 West Fifth Street
Los Angeles
CA
90013
US
|
Family ID: |
38957310 |
Appl. No.: |
11/879456 |
Filed: |
July 16, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11489299 |
Jul 18, 2006 |
|
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11879456 |
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Current U.S.
Class: |
44/280 |
Current CPC
Class: |
C10L 1/326 20130101;
C10J 3/00 20130101; Y02E 50/10 20130101; C10L 9/00 20130101; Y02E
50/14 20130101; C10L 9/086 20130101; C10L 5/44 20130101; C10B 53/02
20130101; C10J 2300/09 20130101; Y02P 20/145 20151101; Y02E 50/30
20130101 |
Class at
Publication: |
44/280 |
International
Class: |
C10L 1/10 20060101
C10L001/10 |
Claims
1. A process for converting biomass into a higher carbon content,
high energy density slurry, comprising providing a mixture of
biomass and water containing up to 60% solids, and heating the
mixture under a non-oxidative gas whereby to obtain a stable slurry
to be obtained containing 20-40% carbon by weight in the
slurry.
2. The process of claim 1 in which the mixture is heated to a
temperature in the range of 170 to 250.degree. C.
3. The process of claim 1 in which the mixture is heated under a
non-oxidative gas at a pressure of 100 to 400 psi.
4. The process of claim 1 in which the mixture is heated to a
temperature of about 200.degree. C. under a non-oxidative gas
pressure of about 150 psi.
5. The process of claim 1 in which the non-oxidative gas is
selected from the group consisting of argon, helium, nitrogen,
hydrogen, carbon dioxide, or gaseous hydrocarbons, or mixtures
thereof.
6. A process for converting biomass into a higher carbon content,
high energy density slurry, comprising providing a mixture of
biomass and water containing 50% solids, and heating the mixture to
a temperature of about 200.degree. C. under a non-oxidative gas
pressure of about 150 psi whereby to obtain a stable slurry.
7. In a process for in which a biomass slurry is fed into a
hydro-gasification reactor, the step of converting the biomass into
a higher carbon content, high energy density slurry, comprising
providing a mixture of biomass and water containing up to 60%
solids, and heating the mixture under a non-oxidative gas whereby
to obtain a stable slurry.
8. The process of claim 7 in which the mixture is heated to a
temperature in the range of 170 to 250.degree. C.
9. The process of claim 7 in which the mixture is heated under a
non-oxidative gas at a pressure of 100 to 400 psi.
10. The process of claim 7 in which the mixture is heated to a
temperature of about 200.degree. C. under a non-oxidative gas
pressure of about 150 psi.
11. The process of claim 7 in which the non-oxidative gas is
selected from the group consisting of argon, helium, nitrogen,
hydrogen, carbon dioxide, or gaseous hydrocarbons, or mixtures
thereof.
12. In a process in which a biomass slurry is fed into a
hydro-gasification reactor, the step of converting the biomass into
a higher carbon content, high energy density slurry, comprising
providing a mixture of biomass and water containing 50% solids, and
heating the mixture to a temperature of about 200.degree. C. under
a non-oxidative gas pressure of about 150 psi whereby to obtain a
stable slurry.
13. The process of claim 12 in which the non-oxidative gas is
selected from the group consisting of argon, helium, nitrogen,
hydrogen, carbon dioxide, or gaseous hydrocarbons, or mixtures
thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of, and claims
the benefit of, patent application Ser. No. 11/489,299, filed Jul.
18, 2006.
FIELD OF THE INVENTION
[0002] The field of the invention is the synthesis of
transportation fuel from carbonaceous feed stocks.
BACKGROUND OF THE INVENTION
[0003] 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.
[0004] 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.
[0005] 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.
[0006] The availability of clean-burning liquid transportation
fuels is a national priority. Producing synthesis gas (which is a
mixture of hydrogen and carbon monoxide) cleanly and efficiently
from carbonaceous sources, that can be subjected to a
Fischer-Tropsch type process to produce clean and valuable
synthetic gasoline and diesel fuels, will benefit both the
transportation sector and the health of society. A Fischer-Tropsch
type process or reactor, which is defined herein to include
respectively a Fischer-Tropsch process or reactor, is any process
or reactor that uses synthesis gas to produce a liquid fuel.
Similarly, a Fischer-Tropsch type liquid fuel is a fuel produced by
such a process or reactor. A Fischer-Tropsch 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 type liquid fuels,
produced from biomass derived synthesis gas, are sulfur-free,
aromatic free, and in the case of synthetic diesel fuel have an
ultrahigh cetane value.
[0007] Biomass material is the most commonly processed carbonaceous
waste feed stock used to produce renewable fuels. 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. For
example, in just the Riverside County, California 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 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.
[0008] The burning of wood in a wood stove is a simple example of
using biomass to produce heat energy. Unfortunately, open burning
of 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 gas for conversion
into electricity.
[0009] 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.
[0010] 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.
[0011] Of particular interest to the present invention are
processes developed more recently in which a slurry of carbonaceous
material is fed into a hydro-gasifier reactor. One such process was
developed in our laboratories to produce synthesis gas in which a
slurry of particles of carbonaceous material in water, and hydrogen
from an internal source, are fed into a hydro-gasification reactor
under conditions to generate rich producer gas. This is fed along
with steam into a steam pyrolytic reformer under conditions to
generate synthesis gas. This process is described in detail in
Norbeck et al. U.S. patent application Ser. No. 10/503,435
(published as US 2005/0256212), entitled: "Production Of Synthetic
Transportation Fuels From Carbonaceous Material Using
Self-Sustained Hydro-Gasification."
[0012] In a further version of the process, using a steam
hydro-gasification reactor (SHR) the carbonaceous material is
heated simultaneously in the presence of both hydrogen and steam to
undergo steam pyrolysis and hydro-gasification in a single step.
This process is described in detail in Norbeck et al. U.S. patent
application Ser. No. 10/911,348 (published as US 2005/0032920),
entitled: "Steam Pyrolysis As A Process to Enhance The
Hydro-Gasification of Carbonaceous Material." The disclosures of
U.S. patent application Ser. Nos. 10/503,435 and 10/911,348 are
incorporated herein by reference.
[0013] All of these processes require the formation of a slurry of
biomass that can be fed to the hydro-gasification reactor. To
enhance the efficiency of the chemical conversions taking place in
these processes, it is desirable to have a low water to carbon
ratio, therefore a high energy density, slurry, which also makes
the slurry more pumpable. High solids content coal/water slurries
have successfully been used in coal gasifiers in the feeding
systems of pressurized reactors. A significant difference between
coal/water slurries and biomass/water slurries is that coal
slurries contain up to 70% solids by weight compared to about 20%
solids by weight in biomass slurries. Comparing carbon content,
coal slurries contain up to about 50% carbon by weight compared to
about 8-10% carbon by weight in biomass slurries. The polymeric
structure if cell walls of the biomass mainly consists of
cellulose, hemicellulose and lignin. All of these components
contain hydroxyl groups. These hydroxyl groups play a key role in
the interaction between water and biomass, in which the water
molecules are absorbed to form a hydrogen bond. This high
hygroscopicity of biomass is generally why biomass slurries are not
readily produced with a high carbon content.
[0014] A number of processes have been developed to produce high
carbon content slurries for use as the feedstock for a
hydro-gasifier. JGC Corporation in Japan developed the Biomass
Slurry Fuel process, which, however must be carried out at
semi-critical conditions, with a temperature of 310.degree. C. and
at a pressure of 2200 psi. The process converts high water content
biomass into an aqueous slurry having a solids content of about
70%, which is the same level as a coal/water slurry. However, it
has to be carried out under high energy conditions.
[0015] Texaco researchers developed a hydrothermal pretreatment
process for municipal sewage sludge that involves heating the
slurry to 350.degree. C. followed by a two stage flash evaporation,
again requiring high energy conditions.
[0016] Traditionally, thermal treatment of wood is a well known
technology in the lumber industry to enhance the structural
property of wood, but not to prepare a slurry. It decreases
hygroscopicity and increases the durability of lumber for
construction. Polymeric chains are cleaved in thermal treatment,
and accessible hydroxyl groups are reduced leading to a limited
interaction with water compared to untreated wood
[0017] Aqueous liquifications of biomass samples have been carried
out in an autoclave in the reaction temperature range of about
277-377.degree. C. at about 725-2900 psi, to obtain heavy oils
rather than slurries, exemplified by the liquification of spruce
wood powder at about 377.degree. C. to obtain a 49% liquid yield of
heavy oil. See A. Demirbas, "Thermochemical Conversion of Biomass
to Liquid Products in the Aqueous Medium", Energy Sources,
27:1235-1243, 2005.
[0018] There is a need for a method for concentrating biomass to
produce a slurry that doesn't require the severe, energy draining
conditions of prior processes.
BRIEF SUMMARY OF THE INVENTION
[0019] The present invention provides an energy efficient process
for converting biomass into a higher carbon content, high energy
density slurry. In particular, water and biomass are mixed at a
temperature and under a pressure that are much lower used in than
prior processes, but under nitrogen, which enables a stable slurry
to be obtained containing up to 60% solids by weight, so as to
provide 20-40% carbon by weight in the slurry. While ranges will be
given in the detailed description, the temperature is nominally
about 200.degree. C. under non-oxidative gas pressure of about 150
psi, conditions that are substantially less stringent than those
required by the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] For a more complete understanding of the present invention,
reference is now made to the following description taken in
conjunction with the accompanying drawings, in which:
[0021] FIG. 1 is a photograph of a 50% by weight biomass water
mixture before treatment with the invention; and
[0022] FIG. 2 is a photograph of the biomass water mixture of FIG.
1 after treatment with the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The term "biomass" as used herein refers broadly to material
which is, or is obtained from, agricultural products, wood and
other plant material, and/or vegetation, and their wastes. The
biomass is mixed with water at the desired weight percentage,
generally from 30 to 70 wt % while at a temperature in the range of
170 to 250.degree. C., most preferably about 200.degree. C., under
non-oxidative gas pressure of 100 to 400 psi, most preferably about
150 psi. The mixture can be placed in an autoclave at room
temperature and ramped to the reaction temperature, or the vessel
can be preheated to the desired temperature before being
pressurized. The reaction temperature can range from 10 minutes to
an hour or more.
[0024] While any non-oxidative gas can be used, such as argon,
helium, nitrogen, hydrogen, carbon dioxide, or gaseous
hydrocarbons, or mixtures thereof, nitrogen is preferred because of
its economic availability. Another preferred non-oxidative gas is
hydrogen if available internally from the process, and which can be
particularly advantageous if carried with the slurry into a
hydro-gasification reactor. While it is desirable to eliminate
oxidative gas, one can use a commercial grade, or less pure, of the
non-oxidative gas so long as no substantial oxidation takes
place.
[0025] The following examples will illustrate the invention.
EXAMPLE 1
[0026] Referring to FIG. 1, a mixture of 50% biomass, consisting of
pine tree particles in water is shown before treatment. Dry pine
sawdust was obtained from American Wood Fibers and the dry White
Cedar from Utah. The sawdust was ground using a commercially
available coffee grinder and sieved to <100 mesh (150 .mu.m).
For the wood pre-treatment, an autoclave system was set up. It
consisted of an Autoclave Engineers EZE-Seal pressure vessel rated
at 3,300 psi at 850.degree. F. The wood sample and deionized water
were weighed and then well mixed by hand to even water distribution
in a large beaker before putting it in the vessel. The amount of
wood added was adjusted for moisture content. The vessel was then
weighed with contents, vacuumed and purged three times with argon,
and finally pressurized to 100.+-.1 psi. The temperature was ramped
to operating temperature (210-230.degree. C.) in about 30 minutes
and then held for 30 minutes. Pressure and internal temperature
were recorded using a data acquisition software. After holding for
30 minutes, application of the heat was stopped and the vessel was
pulled out of the heater. The vessel was left to cool to room
temperature to allow collection of head space gas and sample.
Temperature and pressure were recorded before collection and then
the vessel was weighed.
[0027] The result is shown in FIG. 2, which is a photograph of the
slurry of FIG. 1 after treatment, which was a pumpable slurry
containing 50 wt. % solids in water. Analysis of the head space gas
showed negligible carbon, indicating negligible carbon loss from
the slurry.
EXAMPLE 2
[0028] The procedure of Example 1 was followed but the vessel was
preheated to >200.degree. C. before being put in the heater. The
autoclave was found to reach 230.degree. C. in 15 minutes or less
and then it was held for 30 minutes. The time needed to reach the
target temperature did not have a noticeable physical impact on the
resulting product
EXAMPLE 3
[0029] The method of Example 1 can be carried out but in which the
starting mixture is non-pumpable agricultural waste containing 60
weight percent solids. The result will be a pumpable slurry
containing 60 wt. % solids in water.
EXAMPLE 4
[0030] The method of Example 1 can be carried out but in which the
starting mixture is vegetation containing 40 weight percent solids.
The result will be a pumpable slurry containing 40 wt. % solids in
water.
[0031] The slurry of carbonaceous material resulting from the
process of this invention can be fed into a hydro-gasifier reactor
under conditions to generate rich producer gas. This can be fed
along with steam into a steam pyrolytic reformer under conditions
to generate synthesis gas, as described in Norbeck et al. U.S.
patent application Ser. No. 10/503,435, referred to above.
Alternatively, the resultant slurry can be heated simultaneously in
the presence of both hydrogen and steam to undergo steam pyrolysis
and hydro-gasification in a single step, as described in detail in
Norbeck et al. U.S. patent application Ser. No. 10/911,348,
referred to above.
[0032] 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 such processes and use of
such apparatuses within their scope.
* * * * *