U.S. patent application number 10/523749 was filed with the patent office on 2007-03-29 for method of upgrading biomass, upgraded biomass, biomass water slurry and method of producing same, upgraded biomass gas, and method of gasifying biomass.
This patent application is currently assigned to JGC Corporation. Invention is credited to Tsutomu Katagiri, Teruo Nagai, Jin Ogawa, Yoshinori Suto, Chiaki Suyama, Koji Tamura, Shinichi Tokuda, Masao Tsurui, Takeshi Yamaguchi.
Application Number | 20070068077 10/523749 |
Document ID | / |
Family ID | 31890519 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070068077 |
Kind Code |
A2 |
Suyama; Chiaki ; et
al. |
March 29, 2007 |
Method of upgrading biomass, upgraded biomass, biomass water slurry
and method of producing same, upgraded biomass gas, and method of
gasifying biomass
Abstract
This method of upgrading a biomass comprises: an upgrading step
for performing upgrading treatment of a cellulose based biomass
with an oxygen/carbon atomic ratio of at least 0.5, in presence of
water and under a pressure of at least saturated water vapor
pressure, and reducing said oxygen/carbon atomic ratio of said
biomass to no more than 0.38, and a separation step for separating
an upgraded reactant obtained from said upgrading step into a solid
component and a liquid component.
Inventors: |
Suyama; Chiaki;
(Kanagawa-Ken, JP) ; Tokuda; Shinichi;
(Kanagawa-Ken, JP) ; Tsurui; Masao; (Kanagawa-Ken,
JP) ; Suto; Yoshinori; (Ibaraki-Gun, JP) ;
Tamura; Koji; (Ibaraki-Gun, JP) ; Katagiri;
Tsutomu; (Ibaraki-Gun, JP) ; Nagai; Teruo;
(Tokyo, JP) ; Ogawa; Jin; (Tokyo, JP) ;
Yamaguchi; Takeshi; (Tokyo, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P. O. BOX 5257
NEW YORK
NY
10150-5257
US
|
Assignee: |
JGC Corporation
2-1, Otemachi 2-chome, Chiyoda-ku
Tokyo
JP
The Tokyo Electric Power Company, Inc.
1-3, Uchisaiwai-cho 1-chome, Chiyoda-Ku
Tokyo
JP
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20060112638 A1 |
June 1, 2006 |
|
|
Family ID: |
31890519 |
Appl. No.: |
10/523749 |
Filed: |
August 22, 2005 |
Current U.S.
Class: |
48/197R;
585/242 |
Current CPC
Class: |
C10L 9/086 20130101;
C10J 3/00 20130101; C10J 2300/0973 20130101; Y02E 50/10 20130101;
C10J 2300/092 20130101; C10L 1/326 20130101; C10J 2300/1846
20130101; Y02E 50/30 20130101; C10J 2300/0916 20130101; C10G 31/08
20130101; C10L 5/44 20130101; C10L 2290/04 20130101; C10L 2250/06
20130101; C10L 2290/28 20130101; C10L 2290/24 20130101 |
Class at
Publication: |
048/197.00R;
585/242 |
International
Class: |
C10J 3/46 20060101
C10J003/46 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2002 |
JP |
2002-234987 |
Nov 15, 2002 |
JP |
2002-332190 |
Claims
1. A method of upgrading a biomass, comprising: an upgrading step
for performing upgrading treatment of a cellulose based biomass
with an oxygen/car-bon atomic ratio of at least 0.5, in presence of
water and under a pressure of at least saturated water vapor
pressure, and reducing said oxygen/carbon atomic ratio of said
biomass to no more than 0.38, and a separation step for separating
an upgraded reactant obtained from said upgrading step into a solid
component and a liquid component.
2. A method of upgrading a biomass according to claim 1, wherein
said upgrading treatment is conducted at a temperature of 250 to
380.degree. C., for a period of 5 to 120 minutes.
3. A method of upgrading a biomass according to claim 1, wherein
said cellulose based biomass is a plant based biomass.
4. A method of upgrading a biomass according to claim 1, wherein
said oxygen/carbon atomic ratio of said biomass after said
upgrading treatment is no more than 0.3.
5. A method of upgrading a biomass according to claim 1, wherein
said cellulose based biomass has already undergone shredding, and
is upgraded in a water slurry form.
6. An upgraded biomass, upgraded using a method of upgrading a
biomass according to claim 1.
7. An upgraded biomass according to claim 6, wherein a heating
value on combustion is at least 27 MJ/kg.
8. An upgraded biomass according to claim 6, wherein a volatile
component is at least 50%.
9. A method of producing a biomass water slurry, comprising: an
upgrading step for performing upgrading treatment of a cellulose
based biomass raw material in presence of water and under a
pressure of at least saturated water vapor pressure, a separation
step for separating an upgraded reactant obtained from said
upgrading step into a solid component and a liquid component, a
crushing step for crushing said solid component obtained from said
separation step to an average particle size of no more than 30 nm
using a crushing device, and a mixing step for adding additives,
and where necessary water, to said solid component, and mixing,
wherein said crushing step and said mixing step are performed
either simultaneously or sequentially in this order.
10. A method of producing a biomass water slurry according to claim
9, wherein said cellulose based biomass is a wood based
biomass.
11. A method of producing a biomass water slurry according to claim
9, wherein an average particle size of a solid component crushed in
said crushing step is no more than 20 .mu.m.
12. A method of producing a biomass water slurry according to claim
9, wherein said upgrading treatment is conducted at a temperature
of 250 to 380.degree. C., for a period of 5 to 120 minutes.
13. A method of producing a biomass water slurry according to claim
9, wherein a solid fraction concentration of a biomass water slurry
obtained from said mixing step is at least 50 mass %.
14. A method of producing a biomass water slurry according to claim
9, wherein a cellulose based biomass raw material used in said
upgrading step has already undergone shredding.
15. A method of producing a biomass water slurry according to claim
14, wherein said shredded cellulose based biomass raw material is
used in said upgrading step in a water slurry form.
16. A biomass water slurry comprising, as a solid fraction, at
least 50 mass % of an upgraded biomass produced by upgrading a
cellulose based biomass in presence of water and under a pressure
of at least saturated water vapor pressure, and crushing to an
average particle size of no more than 30 .mu.m.
17. A biomass water slurry according to claim 16, wherein a solid
fraction concentration is from 55 to 75 mass %.
18. A biomass water slurry according to claim 16, wherein an
average particle size of a solid component is no more than 20
.mu.m.
19. A method of gasifying an upgraded biomass, wherein an upgraded
biomass according to claim 6 is subjected to gasification treatment
at a gasification temperature within a range from 800 to
1300.degree. C. and a gasification pressure of 0.1 to 10 MPa, in
presence of a gasifying agent comprising from 25 to 40% of a
quantity of oxygen required for complete combustion, and a required
quantity of steam.
20. An upgraded biomass gas, comprising hydrogen and carbon
monoxide as primary constituents, produced by a method according to
claim 19.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of upgrading a
cellulose based biomass, a method of converting a cellulose based
biomass into a slurry, and a method of gasifying upgraded
biomass.
BACKGROUND ART
[0002] Slurries formed by crushing solid fuels such as coal and
then adding water and additives are known as CWM or CWF (Coal Water
Mixture/Coal Water Fuel), and are consequently attracting
considerable attention as new fuels.
[0003] From the viewpoint of handling, a slurry fuel requires a
viscosity of no more than 1,500 mPas (rotary viscometer, 25.degree.
C., shear rate value of 100 [l/sec], these settings also apply
below). Furthermore, with the demand in recent years for higher
heating values and higher combustion efficiency, heating values of
at least 16.5 MJ/kg (4,000 kcal/kg) are required.
[0004] The increase in carbon dioxide gas emissions as a result of
the huge consumption of fossil fuels is a significant cause of
global warming, and is leading to increased pressure for reductions
in carbon dioxide gas emissions. Biomass, including materials such
as timber, is a non-fossil based renewable energy considered to
produce zero carbon dioxide emissions, and because the ash content
and the sulfur content are extremely low, the investment costs for
combustion facilities can be reduced.
[0005] Timber thinnings, wood scraps from wood processing, prunings
from roadside trees, bagasse, rice straw, and used paper are
largely unused, and are either dumped or disposed of for a fee, and
if these types of materials could be used as fuels, then it would
enable effective use of unused organic resources. These unused
organic resources are solids of a variety of different forms, and
if these solids could be liquefied or converted to a slurry in a
similar manner to coal, then a significant expansion in the range
of possible uses could be expected.
[0006] With these circumstances in mind, at the 15th International
Conference on Coal and Slurry Technology in 1990, the Energy and
Environmental Research Center at the University of North Dakota
reported the generation of a slurry fuel by hot water treatment of
timber.
[0007] However, the solid fraction concentration of the slurry
reported by the University of North Dakota was no more than a
maximum of approximately 48 mass %, and slurries of higher
concentrations could not be produced. At a solid fraction
concentration of approximately 48 mass %, the heating value of the
slurry is only approximately 3,400 kcal/kg. If an attempt is made
to increase the solid fraction concentration in order to increase
the heating value, then the slurry solidifies and cannot be handled
as a slurry.
[0008] Gasification of these unused organic resources of biomass
origin by partial oxidation reactions, and subsequent use as gas
fuels or synthetic gases for chemical reactions is also being
investigated.
[0009] In the case of a direct gasification of a biomass, if the
reaction temperature is less than 800.degree. C., then the
quantities of tar, soot and char produced increase, and operation
of the gasification furnace becomes difficult. As a result, the
partial oxidation reaction temperature must be maintained at a high
temperature of at least 800.degree. C. In order to maintain the
partial oxidation reaction temperature at a high temperature of at
least 800.degree. C., the quantity of oxygen supplied must be
increased, and in such cases the usage efficiency of the coolant
gas decreases. A further problem arose in that the concentration of
H.sub.2 and CO, which represent the active ingredients within the
targeted product gas, also decreases.
[0010] Furthermore, in a method in which a raw material biomass is
crushed to form chips, because the production of chips smaller than
a certain size is impossible, performing the gasification reaction
within a pressurized system was problematic. In addition, because
the biomass cannot be reduced to small enough particles, the rate
of the partial oxidation reaction by oxygen is slow.
DISCLOSURE OF INVENTION
[0011] The inventors of the present invention discovered that by
using a cellulose based biomass with an original oxygen/carbon
atomic ratio of at least 0.5 as a raw material, and then upgrading
the biomass to reduce this oxygen/carbon atomic ratio to no more
than 0.38, a fuel having a superior quality can be stably produced
with a high heating value for the solid component of the upgraded
reactant of at least 25.1 MJ/kg (6,000 kcal/kg).
[0012] A method of upgrading a biomass according to the present
invention comprises an upgrading step for performing upgrading
treatment of a cellulose based biomass with an oxygen/carbon atomic
ratio of at least 0.5, in the presence of water and under a
pressure of at least the saturated water vapor pressure, to reduce
the oxygen/carbon atomic ratio to no more than 0.38, and a
separation step for separating the upgraded reactant obtained from
the upgrading step into a solid component and a liquid component.
An upgraded biomass of the present invention is a biomass obtained
via the above upgrading method.
[0013] From an upgraded biomass of the present invention, a biomass
water slurry having a heating value which is adequate as an
alternative fuel to heavy oil or coal can be easily produced with a
high solid fraction concentration. The upgraded biomass can be used
as a solid fuel in the same manner as coal without further
upgrading process, and can also be used as a soil conditioner or an
adsorbent.
[0014] A method of producing a biomass water slurry according to
the present invention comprises an upgrading step for performing
upgrading treatment of a cellulose based biomass raw material in
the presence of water under a pressure of at least the saturated
water vapor pressure, a separation step for separating the upgraded
reactant obtained from the upgrading step into a solid component
and a liquid component, a crushing step for crushing the solid
component obtained from the separation step to an average particle
size of no more than 30 .mu.m using a crushing device, and a mixing
step for adding additives, and where necessary water, to the solid
component and then mixing. The crushing step and the mixing step
may be conducted either simultaneously, or sequentially in the
order described above.
[0015] According to a method of producing a biomass water slurry of
the present invention, a slurry with a high solid fraction
concentration and a heating value which is adequate as an
alternative fuel to heavy oil or coal, which does not lose slurry
characteristics even on long term storage, and with a viscosity
which enables transportation by pipe can be produced with good
stability using a cellulose based biomass, which conventionally has
not been effectively utilized, as the raw material.
[0016] A biomass water slurry of the present invention comprises,
as a solid fraction, at least 50 mass % of an upgraded biomass,
which is produced by upgrading a cellulose based biomass raw
material in the presence of water and under a pressure of at least
the saturated water vapor pressure, and then crushing the product
to an average particle size of no more than 30 .mu.m.
[0017] A biomass water slurry of the present invention has a high
solid fraction concentration, a heating value which is adequate as
an alternative fuel to heavy oil or coal, and a viscosity which
enables transportation by pipe. The slurry can be stored with good
stability, and even if stored for extended periods, the solid
fraction and liquid within the slurry will not separate.
[0018] A biomass water slurry of the present invention and a method
of producing such a slurry can utilize, as a raw material, a
biomass formed from cellulose products which are conventionally
ineffectively used, including wood based biomass such as timber
thinnings, wood scraps from wood processing such as sawdust, chips
and mills ends, prunings from roadside trees, wood based waste from
construction, bark, and driftwoods; biomass from grasses such as
rice straw, wheat or barley straw and bagasse; as well as bamboo,
bamboo grass, burdock and used paper. Accordingly, resources can be
utilized more effectively, and non-fossil based renewable energy
considered to produce zero carbon dioxide emissions can be
obtained, providing an effective countermeasure against
environmental problems such as increases in carbon dioxide gas
emissions. Furthermore, because the ash content and the sulfur
content are extremely low, the investment costs for combustion
facilities can also be reduced.
[0019] In a method of gasifying an upgraded biomass of the present
invention, an upgraded biomass is subjected to gasification
treatment at a gasification temperature within a range from 800 to
1300.degree. C. and a gasification pressure of 0.1 to 10 MPa, in
the presence of a gasifying agent comprising 25 to 40% of the
quantity of oxygen required for complete combustion, and a required
quantity of steam. An upgraded biomass gas of the present invention
is a gas obtained from the above gasification method comprising
hydrogen and carbon monoxide as primary constituents.
[0020] The aforementioned gasification treatment refers to
gasification by partial oxidation, which utilizes oxygen and steam
as the gasifying agent, and restricts the quantity of oxygen
supplied to approximately 1/4 to 1/2.5 the quantity required for
complete combustion.
[0021] According to a gasification method of the present invention,
the quantity of oxygen supplied during direct oxidation can be
reduced in comparison with the case in which a raw biomass is
directly gasified, and the efficiency of the coolant gas can be
improved. In addition, the concentration of H.sub.2 and CO, which
represent the active ingredients within the gasified product which
is generated, can also be increased.
BEST MODE FOR CARRYING OUT THE INVENTION
[0022] As follows is a description of preferred embodiments of the
present invention. However, the present invention is in no way
limited to the examples presented below, and for example, features
from the examples may also be suitably combined.
[0023] Examples of suitable cellulose based biomass raw materials
which can be used in the present invention include biomass from
cellulose products, including wood based biomass such as timber
thinnings, wood scraps from wood processing such as sawdust, chips
and mills ends, prunings from roadside trees, wood based waste from
construction, bark and driftwoods; biomass from grasses such as
rice straw, wheat or barley straw and bagasse; as well as bamboo,
bamboo grass, burdock and used paper. In addition, provided they
incorporate sufficient cellulose to enable use as a raw material,
sludge, animal dung, agricultural waste and urban waste can also be
used. Of the above cellulose based biomass materials, wood based
biomass is particularly preferred.
[0024] Prior to the upgrading process, the cellulose based biomass
raw material is preferably shredded to produce particle fragments
of no more than 50 mm, and even more preferably no more than 5 mm,
and most preferably no more than 1 mm. When the shredded raw
material is supplied into the upgrading process, the shredded raw
material may be converted to a slurry in an aqueous medium such as
water. However, there is no limitation in the method of
introduction of the shredded raw material. The shredded raw
material may be supplied directly into the upgrading process
without converted into a slurry.
[0025] The upgrading step reduces the oxygen content of the
cellulose based biomass raw material, and improves the heating
value of the biomass as a fuel, and the upgrading treatment is
performed in the presence of water, under a pressure of at least
the saturated water vapor pressure, for a predetermined time
period, and within a predetermined temperature range.
[0026] There are no particular restrictions on the treatment
temperature in the upgrading process, although temperatures from
250 to 380.degree. C. are preferred, and temperatures from 270 to
350.degree. C. are even more desirable. There are no particular
restrictions on the treatment pressure, although the pressure is
preferably from 0.5 to 5 MPa higher, and even more preferably from
1 to 3 MPa higher, than the saturated water vapor pressure.
[0027] There are no particular restrictions on the treatment time,
although time periods from 5 to 120 minutes are preferred, and time
periods from 10 to 60 minutes are even more desirable. The
treatment time relates to the treatment temperature, and as the
treatment temperature increases, the treatment time can be
shortened, whereas if the treatment temperature is low, then the
treatment time should be lengthened.
[0028] The upgrading process may utilize a batch treatment using an
autoclave, or a continuous reaction apparatus formed from either
one, or two or more reaction zones. During the upgrading process,
in order to ensure the temperature is maintained within the above
range, the conditions within the apparatus must be maintained using
pressurized hot water, and a pressure lowering system for cooling
the apparatus and returning the pressure to normal pressure is also
required.
[0029] The upgraded reactant obtained from the upgrading process is
separated into a solid component and a liquid component in a
separation process. The separation process may include not only the
separation of the solid component from the liquid component, but
where necessary also a drying treatment in those cases in which the
water content of the solid component is high. The solid component
is dewatered until the solid fraction concentration is at least 50
mass %, and even more preferably at least 70 mass %. The separated
liquid component may be reused as the water required within the
upgrading process.
[0030] The separation of the solid component and the liquid
component within the separation process may utilize any type of
apparatus typically used for separation, including a leaf filter, a
filter press, a presser, a centrifugal filter, or a centrifugal
separator. The separation may be performed at high temperature,
provided handling is possible, but may also be conducted at room
temperature. In those cases in which the degree of dewatering is
insufficient, drying is performed via a heated drying method until
the required solid fraction concentration is obtained.
[0031] Following removal of the liquid component in the separation
process and dewatering to a predetermined solid fraction
concentration, the solid component is then crushed with a crushing
device to an average particle size of no more than 30 .mu.m.
Examples of suitable crushing devices include ball mills, rod
mills, hammer mills, disc grinding type crushers, fluid energy
mills, or combinations of two or more of the above devices. The
crushing may utilize either dry crushing or wet crushing, although
from the viewpoint of energy efficiency, wet crushing is
preferred.
[0032] In order to manufacture a biomass water slurry of the
present invention, the average particle size of the crushed product
obtained from the solid component by the above separation process
should be no more than 30 .mu.m, and is preferably no more than 20
.mu.m, and even more preferably no more than 15 .mu.m, and most
preferably no more than 10 .mu.M. The average particle size refers
to values measured using a microtrac (FSA model, manufactured by
Nikkiso Co., Ltd.).
[0033] In those cases in which a crushed product with an average
particle diameter of no more than 30 .mu.m is produced via a one
stage crushing treatment, the crushed product may be sent, as is,
to the mixing process. In those cases in which one stage crushing
does not produce an average particle diameter of no more than 30
.mu.m, the crushed product can be re-crushed to reduce the average
particle diameter to a value of no more than 30 .mu.m. Re-crushing
may be performed via a closed system in which sieving is conducted
at a certain particle size, with undersize particles sent directly
to the mixing step, and oversize coarse particles subjected to
re-crushing.
[0034] Subsequently in the mixing process, additives, and where
necessary water, are added to the crushed solid component, and
mixing is performed, yielding a biomass water slurry. Examples of
additives include anionic, cationic and nonionic surfactants, which
can be used singularly, or in combinations of two or more
additives. Appropriate additives are selected in accordance with
the properties of the crushed solid matter.
[0035] Examples of suitable anionic surfactants which can be used
include alkyl sulfate esters, higher alcohol sulfate esters,
nonionic ether sulfate esters, olefin sulfate esters,
polyoxyethylene alkyl(alkylphenol) sulfate esters, alkylallyl
sulfonates, dibasic ester sulfonates, alkylbenzene sulfonates,
alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl
phosphate esters, and acyl sarcosinates.
[0036] Examples of suitable cationic surfactants which can be used
include alkyl amines, quaternary amines, and alkylpyridinium
sulfates.
[0037] Examples of suitable nonionic surfactants which can be used
include polyoxyalkyl ethers, polyoxyethylene alkylphenol ethers,
oxyethylene oxypropylene block polymers, polyoxyethylene
alklyamines, sorbitan fatty acid esters, polyoxyethylene sorbitan
fatty acid esters, alkyltrimethylammonium chloride,
alkyldimethylbenzylammonium chloride, polyoxyethylene fatty acid
esters, aliphatic alcohol polyoxyethylene ethers, polyhydric
alcohol fatty acid esters, and fatty acid ethanolamides.
[0038] Amphoteric surfactants such as alkyl betaines can also be
used.
[0039] The net quantity of additives added is preferably no more
than 1.0 mass %, and even more preferably no more than 0.1 mass %,
relative to the crushed solid component. In those cases in which
water is added together with the additives, then the additives can
be added to the water to produce a predetermined additives
concentration, and this mixture then mixed with the solid
component. Alternatively, the water, the solid component, and the
additives can all be combined simultaneously and then mixed. The
mixer can utilize any form of mixer, although a mixer with a
powerful mixing action is preferable.
[0040] The crushing process and the mixing process may comprise
crushing of the solid fraction in the crushing process, followed by
supply of the crushed solid matter to the mixing process, or
alternatively the crushing process and the mixing process can also
be conducted simultaneously.
[0041] For biomass water slurries obtained via the steps described
above, because higher solid fraction concentration values produce
high heating values, the concentration should be kept as high as
possible. Solid fraction concentration values of at least 50 mass %
are preferred. with concentration levels of at least 55 mass % even
more preferred, and concentration levels of at least 60 mass % the
most desirable.
[0042] On the other hand, in order to enable transportation of a
biomass water slurry by pipe, the biomass water slurry should have
a low viscosity of preferably no more than 1,500 mPas, and even
more preferably no more than 1,000 mPas.
[0043] During conversion to a water slurry, by using an upgraded
crushed biomass with a higher solid fraction concentration than is
desirable for a biomass water slurry, and then mixing this upgraded
crushed biomass while gradually adding either water containing
additives, or additives and water separately, and then stopping the
addition of water at the point the viscosity falls rapidly,
excessive dilution of the upgraded biomass with water can be
avoided, which is preferable.
[0044] A biomass water slurry obtained in the manner described
above has a high solid fraction concentration, and a heating value
which is adequate as an alternative fuel to heavy oil or coal, and
in addition has a viscosity which makes pipe transportation
possible. Furthermore, the slurry can be stored with good
stability, and even if stored for extended periods, the solid
fraction and the liquid within the slurry will not separate to a
degree likely to cause operational problems.
[0045] This biomass water slurry is able to utilize, as a raw
material, a biomass formed from cellulose products which are
conventionally ineffectively used, including wood based biomass
such as timber thinnings, wood scraps from wood processing such as
sawdust, chips and mills ends, prunings from roadside trees, wood
based waste from construction, bark and driftwoods; biomass from
grasses such as rice straw, wheat or barley straw and bagasse; as
well as used paper. Consequently, resources can be utilized more
effectively, and because the slurry is a non-fossil based renewable
energy considered to produce zero carbon dioxide emissions, it
provides one effective countermeasure against environmental
problems such as increases in carbon dioxide gas emissions.
Furthermore, because the ash content and the sulfur content of this
biomass water slurry are extremely low, the investment costs for
combustion facilities can also be reduced.
[0046] A method of upgrading a biomass according to another
embodiment of the present invention uses biomass raw materials such
as those described above in which the oxygen/carbon atomic ratio
within the raw materials is at least 0.5 in all cases. Examples
include Japanese cedar with an oxygen/carbon atomic ratio of 0.620,
pine with a ratio of 0.632, acacia with a ratio of 0.644, bamboo
with a ratio of 0.693, and burdock with a ratio of 0.949. These
oxygen/carbon atomic ratios are values obtained by measurements on
dried samples using mass spectrometry, and although there is some
variation, most values are substantially constant for each variety
of plant. In comparison, the equivalent ratio for coal, although
dependent on the type of coal, is typically from 0.1 to 0.3.
[0047] The cellulose based biomass raw material used in the
upgrading process is shredded first, in the same manner as
described above, and is preferably reduced to particle fragments of
no more than 50 mm, and even more preferably no more than 5 mm, and
most preferably no more than 1 mm.
[0048] In this method of upgrading a biomass, the oxygen/carbon
atomic ratio of the cellulose based biomass raw material is
reduced, and the heating value as a fuel is increased.
Specifically, by conducting the upgrading treatment of a cellulose
based biomass raw material with an oxygen/carbon atomic ratio of at
least 0.5, in the presence of water, under a pressure of at least
the saturated water vapor pressure, for a predetermined time
period, and within a predetermined temperature range, the
oxygen/carbon atomic ratio is reduced to no more than 0.38.
[0049] The quantity of water added to the cellulose based biomass
raw material, including the existing water content within the
cellulose based biomass raw material, is preferably within a range
from approximately 1 to 20 fold the mass (dry base) of the
cellulose based biomass raw material, with quantities from 5 to 15
fold being even more desirable. The water may utilize recirculated
liquid separated from the upgraded reactant in the separation
process described below.
[0050] The treatment temperature in the upgrading process is
preferably within a range from 250 to 380.degree. C., and even more
preferably from 270 to 350.degree. C. The operating pressure is
preferably from 0.5 to 5 MPa higher, and even more preferably from
1 to 3 MPa higher, than the saturated water vapor pressure.
[0051] There are no particular restrictions on the treatment time
in the upgrading process, although time periods from 5 to 120
minutes are preferred, and time periods from 10 to 60 minutes are
even more desirable. As the treatment temperature increases, the
treatment time can be shortened, whereas if the treatment
temperature is low, then the treatment time should be
lengthened.
[0052] The upgrading process may utilize a batch treatment using an
autoclave, or a continuous reaction apparatus formed from either
one, or two or more reaction zones. During the upgrading process,
in order to ensure the temperature is maintained within the above
range, the conditions within the apparatus must be maintained using
pressurized hot water, and a pressure lowering system for cooling
the apparatus and returning the pressure to normal pressure is also
required.
[0053] The upgraded reactant obtained from the upgrading process is
separated into a solid component and a liquid component in a
separation process. The separation process of the present invention
includes not only the separation of the solid component from the
liquid component, but where necessary also a drying treatment using
heated drying or the like, which is performed in those cases in
which the water content of the solid component is high.
[0054] The solid component produced from the separation process is
obtained as an upgraded biomass cake. The solid fraction
concentration of this cake is preferably at least 50 mass %, and
even more preferably at least 60 mass %. The liquid component
separated during the separation process may be reused as the water
required within the upgrading process.
[0055] The separation of the solid component and the liquid
component within the separation process may utilize any type of
apparatus typically used for separation, including a leaf filter, a
filter press, a presser, a centrifugal filter, or a centrifugal
separator. The separation may be performed at high temperature,
provided handling is possible, but may also be conducted at room
temperature.
[0056] The conditions within the upgrading process of the present
invention, such as the upgrading temperature, pressure, and time
period are suitably selected so as to achieve an upgraded reactant
with an oxygen/carbon atomic ratio of no more than 0.38, and
preferably no more than 0.3. Taking into consideration the energy
efficiency during the upgrading process, the lower limit for the
oxygen/carbon atomic ratio is approximately 0.1.
[0057] Comparing the oxygen/carbon atomic ratio in the biomass with
the production of charcoal obtained by carbonization of timber, in
the case of charcoal, the timber is baked at 400 to 1000.degree. C.
and undergoes thermal decomposition at a high temperature, and the
product has a carbon content of greater than 90% and an oxygen
content of almost 0, whereas in the present invention, upgrading
treatment is performed in the presence of water, at a lower
temperature and a higher pressure than that used in the charcoal
baking, and a mild thermal decomposition process which partially
deoxygenates the raw material produces an oxygen/carbon atomic
ratio of no more than 0.38.
[0058] If the weight of the raw material timber is deemed 100, then
the recovered weight in the case of charcoal is approximately 10 to
25%, whereas the recovered weight of upgraded reactant in the
present invention is at least 40%, meaning the fuel recovery rate
is high.
[0059] The solid component of the upgraded reactant obtained in the
separation process following the upgrading treatment to reduce the
oxygen/carbon atomic ratio to no more than 0.38 has a heating value
per dried weight unit of at least 27 MJ/kg. Even if converted to a
water slurry to form a slurry fuel as described below, this type of
solid component still yields a high quality fuel with a heating
value per dried weight unit of at least 16.5 MJ/kg (at least 4,000
kcal/kg). In other words, with this upgrading method, crushing of
the upgraded product is simple, and an upgraded biomass can be
produced which displays good affinity for water and can be
converted to a high density water slurry fuel. In addition to
slurry fuels, this upgraded biomass may also be combusted directly
as a solid component, or can also be used as a high heating value
fuel, and mixed with existing fuels such as coal and then combusted
within a boiler.
[0060] The weight of the volatile component within the upgraded
biomass is preferably at least 50%. The weight of the volatile
component refers to the value measured in accordance with JIS
M8812, and is the value obtained by subtracting the water content
from the mass reduction ratio observed when a sample is heated for
7 minutes at 900.degree. C. without any air contact. The larger the
volatile component, the better the combustibility will become.
[0061] This upgraded biomass can be converted to a low viscosity
slurry with a high solid fraction concentration, which is capable
of pipe transportation, by adding additives, adding further water
if necessary, and then crushing and mixing the mixture, for
example. The solid fraction concentration is typically at least 50
mass %, and preferably at least 55 mass %, and even more preferably
at least 60 mass %.
[0062] Examples of suitable additives include the anionic, cationic
and nonionic surfactants described above, which can be used
singularly, or in combinations of two or more additives, and can be
selected in accordance with the properties of the crushed solid
matter.
[0063] In this method, the net quantity of additives added is
preferably no more than 1.0 mass %, and even more preferably no
more than 0.1 mass %, relative to the solid component. In those
cases in which water is added together with the additives, then in
the same manner as described above, a mixture of the additives and
water can be mixed with the solid component, or alternatively, the
water, the solid component, and the additives can all be combined
simultaneously and then mixed.
[0064] In the crushing of the upgraded biomass, crushing is
conducted so that the average particle size of the upgraded biomass
particles is preferably no more than 30 .mu.m, and even more
preferably no more than 20 .mu.m, and most preferably no more than
15 .mu.m. The average particle size refers to values measured using
a microtrac (FSA model, manufactured by Nikkiso Co., Ltd.).
[0065] Examples of suitable crushing devices that can be used
include ball mills, rod mills, hammer mills, disc grinding type
crushers, fluid energy mills, or combinations of two or more of the
above devices. The crushing may utilize either dry crushing or wet
crushing, although from the viewpoint of energy efficiency, wet
crushing is preferred.
[0066] Either one stage or multistage crushing can be used. In the
case of multistage crushing, a closed system may be used in which
the crushed product from the first stage is sieved at a certain
particle size, and oversize coarse particles are subjected to
re-crushing.
[0067] Mixing the crushed upgraded biomass enables the production
of a biomass water slurry. The mixer can utilize any form of mixer,
although a mixer with a powerful mixing action is preferable. The
crushing process and the mixing process may comprise crushing of
the solid fraction in the crushing process, followed by supply of
the crushed solid matter to the mixing process, or alternatively
the crushing process and the mixing process can also be conducted
simultaneously. The slurry may be produced by only one of the
crushing process and the mixing process.
[0068] During conversion to a biomass water slurry through mixing,
by using an upgraded crushed biomass with a higher solid fraction
concentration than is desirable for a biomass water slurry, and
then mixing this upgraded crushed biomass while gradually adding
either water containing additives, or additives and water
separately, and then stopping the addition of water at the point
the viscosity falls rapidly, excessive dilution of the upgraded
biomass with water can be avoided, which is desirable.
[0069] A biomass water slurry obtained in the manner described
above has a high solid fraction concentration, and a heating value
which is adequate as an alternative fuel to heavy oil or coal, and
also displays a viscosity which makes pipe transportation
possible.
[0070] Because the upgraded biomass is subjected to upgrading
treatment at a pressure of at least the saturated water vapor
pressure, to generate an oxygen/carbon atomic ratio of no more than
0.38, the biomass contains no toxic bacteria, and is also quite
porous, and consequently when mixed with soil, the biomass provides
breeding sites for useful soil bacteria and also adsorbs harmful
components within the soil, meaning the upgraded biomass is useful
as a soil conditioner, and can also be used as an adsorbent.
[0071] In addition, because this biomass water slurry utilizes, as
a raw material, a biomass formed from cellulose products which are
conventionally ineffectively used, including wood based biomass
such as timber thinnings, wood scraps from wood processing such as
sawdust, chips and mills ends, prunings from roadside trees, wood
based waste from construction, bark and driftwoods; biomass from
grasses such as rice straw, wheat or barley straw and bagasse; as
well as used paper, resources can be utilized more effectively, and
a non-fossil based renewable energy considered to produce zero
carbon dioxide emissions can be generated, providing one effective
countermeasure against environmental problems such as increases in
carbon dioxide gas emissions. Furthermore, because the ash content
and the sulfur content of this biomass water slurry are extremely
low, the investment costs for combustion facilities can also be
reduced.
[0072] Next is a description of a method of gasifying an upgraded
biomass.
[0073] In order to gasify an upgraded biomass obtained through the
method described above, oxygen and steam are used as a gasifying
agent. The quantity of oxygen is set at approximately 1/4 to 1/2.5
the quantity required for complete combustion of the upgraded
biomass. The quantity of oxygen required for gasification is
related to the gasification temperature. Oxygen may be substituted
with air. In this method, for a preset gasification temperature,
gasification can be achieved with a smaller quantity of oxygen than
the case in which a raw biomass is gasified.
[0074] There are no particular restrictions on the gasification
temperature, provided the temperature is sufficient for
gasification to occur, and in order to suppress the generation of
tar and soot, the gasification temperature is typically set within
a range from 800 to 1300.degree. C., and preferably from 800 to
1200.degree. C. There are no particular restrictions on the
gasification pressure, and values from 0.1 to 10 MPa can be used.
Taking into consideration treatment of the generated gas during
later stages, it is preferable that the gasification is conducted
at a high pressure of 0.5 to 10 MPa.
[0075] The quantity of steam supplied during the gasification
treatment is preferably determined so that (supplied quantity of
oxygen/2+quantity of oxygen within supplied steam+quantity of
oxygen within raw material)/(quantity of carbon within raw
material) [mol/mol]=2.0 to 6.0. In addition to oxygen and steam,
other gasifying agents such as carbon dioxide may also be used
where necessary.
[0076] The upgraded biomass used in the gasification may be a dried
biomass, a biomass containing water, or a slurry produced by adding
water. A powder or slurry of an upgraded biomass to which coal
powder has been added may also be used.
[0077] The upgraded biomass is easier to crush than a raw biomass,
and can also be placed under high pressure and supplied to a
gasification reaction vessel, and is consequently a desirable raw
material for obtaining a high pressure gasification product.
[0078] By using an upgraded biomass in the gasification process,
the quantity of oxygen supplied can be reduced in comparison with
the case in which a raw biomass is oxidized directly, and the
efficiency of the coolant gas can be improved. In addition, the
concentration of H.sub.2 and CO, which represent the active
ingredients within the gasified product which is generated, can
also be improved.
[0079] Furthermore, if an upgraded biomass is used, then the
reduction of the biomass to small particles by crushing can be
achieved with greater reliability, direct gasification by a partial
oxidation reaction can be performed efficiently, and the
gasification reaction can be conducted easily at a high
pressure.
[0080] Furthermore, gasification of biomass comprising wood or the
like is usually achievable at low temperatures of approximately
800.degree. C., but tar and carbon deposition cause a reduction in
gasification rate, and have been reported to cause operational
trouble (reference: Biomass Handbook, edited by the Japan Institute
of Energy, 2002, p95). In contrast, in a gasification method of the
present invention, tar and soot deposition does not occur, and the
reduction in efficiency and operational troubles described above do
not arise.
EXAMPLES
Example 1
[0081] 3,300 g of water was added to 350 g of dried Acacia mangium
(timber) which had been shredded to particles of no more than 1 mm,
and the mixture was then stirred. The thus obtained mixture was
placed in a 10 liter autoclave, and upgrading treatment was
performed by raising the temperature from room temperature to
330.degree. C. over a 3 hour period, and adjusting the pressure to
15.6 MPa. This state was then maintained for 10 minutes, and the
mixture was then cooled to 80.degree. C. over a 3 hour period, to
yield a black colored slurry. This slurry was filtered using a
Nutsche filter, and the thus obtained solid component was dried,
and yielded 158 g of a black colored powder.
[0082] 50 g of this powder was crushed for 30 hours in a 1 liter
ball mill, and 40 g of a fine powder was recovered. Measurement of
the particle size distribution of this fine powder using a
microtrac (FSA model, manufactured by Nikkiso Co., Ltd.) revealed
an average particle size of 8.2 .mu.m.
[0083] With 40 g of this fine powder being mixed, water containing
2 mass % of a surfactant (NSF, manufactured by Dai-Ichi Kogyo
Seiyaku Co., Ltd.) was added gradually, and at the point the slurry
viscosity fell rapidly, addition of the water was stopped, thereby
yielding a high viscosity slurry. The solid fraction concentration
of this slurry was 67 mass %, and the viscosity was 770 mPas. This
slurry remained in a slurry state even after storage for 2 months
at room temperature.
[0084] When this biomass water slurry was used as the fuel for a
combustion test furnace for observing a droplet combustion process,
it was evident that the fuel could be used as an adequate
alternative fuel to heavy oil. Furthermore, in terms of the facts
that the ash content was less than 1 mass %, and the sulfur content
was essentially non-existent, the biomass water slurry was superior
to heavy oil.
Example 2
[0085] With the exceptions of performing the upgrading treatment
using 470 g of Acacia mangium which had been dried and shredded to
particles of no more than 1 mm and 4,300 g of water, and adjusting
the set temperature and set pressure for the upgrading treatment to
300.degree. C. and 11 MPa respectively, a slurry was obtained in
the same manner as the example 1. The average particle size of the
fine powder following crushing with the ball mill was 10.3
.mu.m.
[0086] The solid fraction concentration of the slurry obtained
after mixing was 66 mass %, and the slurry viscosity was 830 mPas.
This slurry remained in a slurry state even after storage for 2
months at room temperature. The characteristics of this slurry as a
fuel were the same as those of the biomass water slurry of the
example 1.
Example 3
[0087] With the exceptions of performing the upgrading treatment
using 290 g of Acacia mangium which had been dried and shredded to
particles of no more than 1 mm and 2,700 g of water, and adjusting
the set temperature and set pressure for the upgrading treatment to
350.degree. C. and 18.8 MPa respectively, a slurry was obtained in
the same manner as the example 1. The average particle size of the
fine powder following crushing with the ball mill was 9.5
.mu.m.
[0088] The solid fraction concentration of the slurry obtained
after mixing was 68.5 mass %, and the slurry viscosity was 990
mPas. This slurry remained in a slurry state even after storage for
2 months at room temperature.
Example 4
[0089] With the exceptions of performing the upgrading treatment
using 430 g of Japanese cedar which had been dried and shredded to
particles of no more than 1 mm and 3,600 g of water, and adjusting
the set temperature and set pressure for the upgrading treatment to
270.degree. C. and 14 MPa respectively, a slurry was obtained in
the same manner as the example 1. The average particle size of the
fine powder following crushing with the ball mill was 11.3
.mu.m.
[0090] The solid fraction concentration of the slurry obtained
after mixing was 67 mass %, and the slurry viscosity was 770 mPas.
This slurry remained in a slurry state even after storage for 2
months at room temperature. The characteristics of this slurry as a
fuel were the same as those of the biomass water slurry of the
example 1.
Example 5
[0091] With the exceptions of performing the upgrading treatment
using 460 g of Acacia mangium which had been dried and shredded to
particles of no more than 1 mm, using 3,200 g of the liquid
obtained by filtering the upgrading treatment slurries obtained in
the example 2 and the example 3 instead of water, and adjusting the
set temperature and set pressure for the upgrading treatment to
330.degree. C. and 18 MPa respectively a slurry was obtained in the
same manner as the example 1. The average particle size of the fine
powder following crushing with the ball mill was 11 .mu.m.
[0092] The solid fraction concentration of the slurry obtained
after mixing was 70 mass %, and the slurry viscosity was, 1,100
mPas. This slurry remained in a slurry state even after storage for
2 months at room temperature.
Example 6
[0093] The upgrading treatment was performed using 470 g of dried
Acacia mangium which had been shredded to particles of no more than
1 mm and 4,300 g of water, and with the set temperature and set
pressure for the upgrading treatment set to 300.degree. C. and 11
MPa respectively. Furthermore, with the exception of altering the
time for which the set temperature was maintained to 60 minutes, a
slurry was obtained in the same manner as the example 1. The
upgrading treatment yielded 223 g of a black colored powder. The
average particle size of the fine powder following crushing with a
ball mill was 9.9 .mu.m.
[0094] The solid fraction concentration of the slurry obtained
after mixing was 70 mass %, and the slurry viscosity was 940 mPas.
This slurry remained in a slurry state even after storage for 2
months at room temperature.
Comparative Example 1, Examples 7 to 9
[0095] With the exceptions of performing the upgrading treatment
using 470 g of Acacia mangium which had been dried and shredded to
particles of no more than 1 mm and 4,300 g Of water, and adjusting
the set temperature and set pressure for the upgrading treatment to
300.degree. C. and 11 MPa respectively in the same manner as the
example 2, a black colored powder was obtained in the same manner
as the example 1. This was crushed finely with a ball mill,
yielding separate 50 g samples of finely crushed powder after 4
hours (comparative example 1), after 8 hours (example 7), after 16
hours (example 8) and after 32 hours (example 9) respectively. The
average particle sizes of each powder sample were 35.2, 25.6, 15.1
and 10.3 .mu.m respectively.
[0096] The solid fraction concentrations of each sample when
converted to a slurry under the same conditions were 47, 55, 60 and
66 mass % respectively, and in the slurry produced after 4 hours of
crushing (comparative example 1), the solid settled out after a few
days and the slurry state was lost. The other slurries (example 7
through example 9) all remained in a slurry state even after
storage for 2 months at room temperature.
Example 10
[0097] 9,000 g of water was added to 1,000 g of dried Japanese
cedar timber which had been shredded to particles of no more than 1
mm, and the pressure of the stirred slurry was raised to 15 MPa
using a pump. The slurry was then fed into an electrically heated
reaction apparatus with a preheating section of internal diameter 8
mm, an upgrading section, and a cooling section, and was upgraded
in the upgrading section at a temperature of 300.degree. C. and
with a residence time of 30 minutes. Then it was cooled to
90.degree. C. by the cooling section, and was left to stand at
normal pressure. The thus obtained slurry was filtered using a
Nutsche filter, and the solid component was then dried, and yielded
420 g of a black colored powder. Drying treatment was conducted for
10 hours at 105.degree. C., and the water content within the
treated product was reduced to no more than 2 mass %.
[0098] Determination of the elemental composition of the dried
powder using a CHN coder manufactured by Yanaco Corporation,
revealed an oxygen/carbon atomic ratio of 0.258, and furthermore
the high heating value (the heating value during combustion,
including the heat of condensation of generated H.sub.2O) was 29.9
MJ/kg (7,150 kcal/kg), and the volatile component was 60%. The
oxygen/carbon atomic ratio of the raw material Japanese cedar was
0.620, the high heating value was 20.0 MJ/kg (4,780 kcal/kg), and
the volatile component was 85%.
[0099] 50 g of the black colored powder was crushed for 30 hours in
a 1 liter ball mill, and 40 g of a fine powder was recovered.
Measurement of the particle size distribution of this fine powder
using a microtrac (FSA model, manufactured by Nikkiso Co., Ltd.)
revealed an average particle size of 8.2 .mu.m.
[0100] With 40 g of this fine powder being mixed, water containing
2 mass % of a surfactant (NSF, manufactured by Dai-Ichi Kogyo
Seiyaku Co., Ltd.) was added gradually, and at the point the slurry
viscosity fell rapidly, addition of the water was stopped, thereby
yielding a high viscosity slurry. The solid fraction concentration
of this slurry was 67 mass %, and the viscosity was 770 mPas.
[0101] When this biomass water slurry was used as the fuel for a
combustion test furnace for observing a droplet combustion process,
it was evident that the fuel could be used as an adequate
alternative fuel to heavy oil. Furthermore, in terms of the facts
that the ash content was less than 1 mass %, and the sulfur content
was essentially non-existent, the biomass water slurry was superior
to heavy oil.
Example 11
[0102] Using the same raw material and apparatus as the example 10,
but with the exceptions of setting the raised pressure applied by
the pump to 9 MPa, and setting the temperature of the upgrading
section to 270.degree. C., the raw material was upgraded, filtered
and dried in the same manner as the example 10, and yielded a black
colored powder. The oxygen/carbon atomic ratio of the thus obtained
black colored powder was 0.262, the high heating value was 29.8
MJ/kg (7,120 kcal/kg), and the volatile component was 60%.
Example 12
[0103] Using the same raw material and apparatus as the example 10,
but with the exceptions of setting the raised pressure applied by
the pump to 7 MPa, and setting the temperature of the upgrading
section to 250.degree. C., the raw material was upgraded, filtered
and dried in the same manner as the example 10, and yielded a black
colored powder. The oxygen/carbon atomic ratio of the thus obtained
black colored powder was 0.376, the high heating value was 27.0
MJ/kg (6,450 kcal/kg), and the volatile component was 68%.
Example 13
[0104] Using the same raw material and apparatus as the example 10,
but with the exception of setting the residence time within the
upgrading section to 5 minutes, the raw material was upgraded,
filtered and dried in the same manner as the example 10, and
yielded a black colored powder. The oxygen/carbon atomic ratio of
the thus obtained black colored powder was 0.260, the high heating
value was 29.7 MJ/kg (7,100 kcal/kg), and the volatile component
was 74%.
Example 14
[0105] With the exception of replacing the Japanese cedar raw
material with Acacia mangium (oxygen/carbon atomic ratio: 0.644,
high heating value: 21.0 MJ/kg (5,020 kcal/kg), volatile component:
84%) which had been dried and shredded in the same manner, a black
colored powder was obtained in the same manner as the example 10.
The oxygen/carbon atomic ratio of the thus obtained black colored
powder was 0.243, the high heating value was 30.0 MJ/kg (7,170
kcal/kg), and the volatile component was 60%.
Example 15
[0106] With the exceptions of replacing the Japanese cedar raw
material with pine (oxygen/carbon atomic ratio: 0.632, high heating
value: 21.0 MJ/kg (5,010 kcal/kg), volatile component: 84%) which
had been dried and shredded in the same manner, setting the raised
pressure applied by the pump to 10 MPa, and setting the temperature
of the upgrading section to 270.degree. C., a black colored powder
was obtained in the same manner as the example 10. The
oxygen/carbon atomic ratio of the thus obtained black colored
powder was 0.230, the high heating value was 30.6 MJ/kg (7,300
kcal/kg), and the volatile component was 62%.
Example 16
[0107] With the exception of replacing the Japanese cedar raw
material with bamboo (oxygen/carbon atomic ratio: 0.632, high
heating value: 22.0 MJ/kg (5,250 kcal/kg), volatile component: 83%)
which had been dried and shredded in the same manner, a black
colored powder was obtained in the same manner as the example 10.
The oxygen/carbon atomic ratio of the thus obtained black colored
powder was 0.216, the high heating value was 30.9 MJ/kg (7,380
kcal/kg), and the volatile component was 61%.
Example 17
[0108] With the exception of replacing the Japanese cedar raw
material with burdock (oxygen/carbon atomic ratio: 0.949, high
heating value: 19.9 MJ/kg (4,760 kcal/kg), volatile component: 86%)
which had been dried and shredded in the same manner, a black
colored powder was obtained in the same manner as the example 10.
The oxygen/carbon atomic ratio of the thus obtained black colored
powder was 0.268, the high heating value was 29.6 MJ/kg (7,070
kcal/kg), and the volatile component was 59%.
Comparative Example 2
[0109] Using the same raw material and apparatus as the example 10,
but with the exceptions of setting the raised pressure applied by
the pump to 5 MPa, and setting the temperature of the upgrading
section to 230.degree. C., the raw material was upgraded, filtered
and dried in the same manner as the example 10, and yielded a dark
brown colored powder. The oxygen/carbon atomic ratio of the thus
obtained powder was 0.496, the high heating value was 23.9 MJ/kg
(5,700 kcal/kg), and the volatile component was 74%.
Comparative Example 3
[0110] Using the same raw material and apparatus as the example 10,
but with the exceptions of setting the raised pressure applied by
the pump to 3 MPa, and setting the temperature of the upgrading
section to 200.degree. C., the raw material was upgraded, filtered
and dried in the same manner as the example 10, and yielded a brown
colored powder. The oxygen/carbon atomic ratio of the thus obtained
brown colored powder was 0.615, the high heating value was 20.1
MJ/kg (4,800 kcal/kg), and the volatile component was 84%.
Example 18
[0111] For a gasification reaction using oxygen blowing, in which
the dried black colored powder obtained through the upgrading
treatment of the example 10 (oxygen/carbon atomic ratio: 0.258,
high heating value: 29.9 MJ/kg) was supplied at a rate of 1,466
kg/hr, the quantity of oxygen required to ensure a gasification
reaction vessel temperature of 1,100.degree. C., and the
composition of the gas at that time, were determined by simulation
calculations.
[0112] Steam was supplied so that (supplied quantity of
oxygen/2+supplied quantity of steam+quantity of oxygen within raw
material)/(quantity of carbon within raw material)=4.0 [mol/mol].
The results are shown in Table 1.
[0113] The quantity of oxygen required was 28.1 kg-mol/hr, the
quantity of (CO+H.sub.2) within the product gas was 130.2
kg-mol/hr, and the (CO+H.sub.2) gas concentration referenced to the
dry gas was 84.1%. Furthermore, the cool gas efficiency was
84.9%.
[0114] These simulation results are determined based on the product
gas composition reaching a thermodynamic equilibrium within the
reversible reaction equations of equation (I) and equation (2)
shown below. CH.sub.4+H.sub.2O.rarw..fwdarw.CO+3H.sub.2 (1)
CO+H.sub.2O.rarw..fwdarw.CO.sub.2+H.sub.2 (2)
[0115] When an apparatus was assembled, and an actual test was
performed, the results obtained were substantially the same as
those of the simulation calculations. Because the gasification was
conducted at approximately 1100.degree. C., the production of
carbon and tar is limited, and consequently these factors were
ignored in the calculations.
Comparative Example 4
[0116] For a gasification reaction using oxygen blowing, in which
dried Japanese cedar (oxygen/carbon atomic ratio: 0.620, high
heating value: 20.0 MJ/kg) was supplied at a rate of 2,340 kg/hr,
the quantity of oxygen required to ensure a gasification reaction
vessel temperature of 1,100.degree. C., and the composition of the
gas at that time, were determined by simulation calculations.
[0117] Steam was supplied so that (supplied quantity of
oxygen/2+supplied quantity of steam+quantity of oxygen within raw
material)/(quantity of carbon within raw material)=4.0 [mol/mol].
The reason that the raw material quantity was set at 2,340 kg/hr
was to ensure that the quantities of (CO+H.sub.2) generated, which
represent the active ingredients within the product gas, were the
same as in the example 18. The results are shown in Table 1. The
quantity of oxygen required was 39.7 kg-mol/hr, the quantity of
(CO+H.sub.2) within the product gas was 130.2 kg-mol/hr, the same
as the example 18, but the (CO+H.sub.2) (gas concentration
referenced to the dry gas was 77.8%. Furthermore, the cool gas
efficiency was lower, at 79.3%. TABLE-US-00001 TABLE 1 Comparative
Example 18 Example 4 Raw material Dried upgraded Dried Japanese
material cedar Setting of Conditions C = 100 Quantity of (CO +
kgmol H.sub.2) generated (atomic mol) set as for the example 18,
quantity of O.sub.2 for 1100.degree. C. then calculated Raw
material supply rate [kg/hr] 1466 2348 Raw material heating value
7150 4730 HHV [kcal/kg] Oxygen supply rate [kg-mol/hr] 28.1 39.7
Ratio relative to oxygen 26.5 29.1 quantity required for complete
combustion [%] Steam supply rate [kg-mol/hr] 89.6 79.1 Gasification
pressure [MPa] 70 70 Gasification temperature 1105 1102
(calculated) [.degree. C.] Product gas CO 60.9 62.9 quantities
H.sub.2 69.3 67.3 [kg-mol/hr] CO.sub.2 24.0 36.7 H.sub.2O 58.9 84.4
CH.sub.4 0.7 0.4 Cool gas efficiency *) [%] 84.9 79.3 *) Cool gas
efficiency = HHV of combustible gas within product gas/HHV of
gasified raw material, HHV: high heating value
[0118] In an oxygen blowing gasification method, the quantity of
oxygen used has a large effect on the economic viability, and from
a comparison of the example 18 and the comparative example 4, it is
evident that using the upgraded material as a raw material enables
a reduction in the oxygen supply rate and an improvement in the
cool gas efficiency over the case using a raw biomass. Furthermore,
the concentration of the active ingredients within the product gas
can also be improved.
INDUSTRIAL APPLICABILITY
[0119] According to the present invention, a slurry with a high
solid fraction concentration and a heating value which is adequate
as an alternative fuel to heavy oil or coal, which does not lose
slurry characteristics even on long term storage, and with a
viscosity which enables transportation by pipe, can be produced
with good stability using a cellulose based biomass, which
conventionally has not been effectively utilized, as the raw
material.
* * * * *