U.S. patent application number 12/876481 was filed with the patent office on 2011-03-10 for method for pretreating and using the fine particles of a biomass in a gasification process and an apparatus utilizing said method.
Invention is credited to Jorma Kautto, Mika TIMONEN.
Application Number | 20110056820 12/876481 |
Document ID | / |
Family ID | 41136329 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056820 |
Kind Code |
A1 |
TIMONEN; Mika ; et
al. |
March 10, 2011 |
METHOD FOR PRETREATING AND USING THE FINE PARTICLES OF A BIOMASS IN
A GASIFICATION PROCESS AND AN APPARATUS UTILIZING SAID METHOD
Abstract
Method for pretreating the fine particles of a biomass. What is
essential in the method is that, for pretreating the fine particles
for the gasification, the fine particles are granulated by means of
pellet presses or suitable briquetting devices or corresponding
granulating devices such that their particle size is advantageous
for coking and for the quenching of syngas.
Inventors: |
TIMONEN; Mika; (Jyvaskyla,
FI) ; Kautto; Jorma; (Vantaa, FI) |
Family ID: |
41136329 |
Appl. No.: |
12/876481 |
Filed: |
September 7, 2010 |
Current U.S.
Class: |
201/6 ; 264/109;
425/363 |
Current CPC
Class: |
Y02E 50/10 20130101;
C10L 5/363 20130101; Y02E 50/30 20130101; C10L 5/361 20130101; C10L
5/44 20130101 |
Class at
Publication: |
201/6 ; 425/363;
264/109 |
International
Class: |
C10B 45/02 20060101
C10B045/02; C10L 9/00 20060101 C10L009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2009 |
FI |
20090327 |
Claims
1. Method for pretreating the fine particles of a biomass
characterized in that in the method for pretreating the fine
particles for the gasification the fine particles are granulated by
means of pellet presses, briquetting devices or other devices
suitable for granulation such that their particle size is
advantageous for coking and the quenching of syngas.
2. Method according to claim 1, characterized in that in the method
the fine particles are pretreated into a pellet, briquette or
corresponding product such that they stay intact in the coking
reactor without being exposed to the pyrolysis gas, thereby
increasing the optimal size of the material to be led to the
quenching zone in the method for improving the efficiency ratio of
the syngas.
3. Method according to claim 1, characterized in that in the method
the fine particles are separated from the raw material flow by
screening after drying or by screening before drying from the wet
or partially dried biomass.
4. Method according to claim 1, characterized in that in the method
a drum dryer is used for drying the fine particles.
5. Method according to claim 1, characterized in that in the method
pellets and/or briquettes are most preferably produced of peat,
logging residue chips, bark chips or by-products of the wood
processing industry, such as sawdust, screening chips or cutter
chips or field biomass, such as reed canary grass or straw, as
separate clean fine particles or alternatively as mixed pellets
and/or briquettes made of one or more type(s) of different fine
particles.
6. Method according to claim 1, characterized in that in the method
the fine particles are separately separated from the raw material
flow, such as from the wood chips and bark chips, into fine
particles of their own for producing pellets and/or briquettes
and/or other corresponding products.
7. Method according to claim 1, characterized in that preferably
2-5 different fuel feed bins are used in the gasification process
according to the method for dispensing raw material, such as wood
chips, bark chips and pellets and/or briquettes made of fine
particles, suitably proportioned into the reactor.
8. Method according to claim 1, characterized in that the fraction
that goes through a screen of 2-20 mm, is used as fine particles in
the method, a preferable particle size is in the range 2-10 mm and
the particle size of a pellet or briquette produced of said fine
particles is in the range 6-16 mm in diameter and the length is
approx. 2-4 times the diameter, and the humidity 5-15%, most
preferably approx. 10%.
9. Use of pellet presses, briquetting devices and/or corresponding
granulating devices for pretreating the fine particles of a biomass
for the gasification.
10. Use for the purpose of gasification according to claim 9 such
that for achieving suitable syngas the particle size of pellets is
advantageous in quenching.
11. Use for pretreating of fine particles into pellets according to
claim 9 such that they stay intact in the coking reaction without
being exposed to the pyrolysis gas, thereby simultaneously
increasing the optimal size of the material to be led to the
quenching zone for increasing the amount of syngas.
12. Use according to claim 9 of a drum dryer used for drying of
fine particles.
13. Apparatus for pretreating the fine particles of a biomass
characterized in that the apparatus comprises one or more pellet
presses, a suitable briquetting device and/or corresponding
granulating device for pretreating the fine particles for the
gasification, in which case the fine particles are granulated by
means of pellet presses, suitable briquetting devices and/or
corresponding granulating devices into a suitable particle size and
led such that their particle size is advantageous for coking and
the quenching of syngas.
14. Apparatus according to claim 13, characterized in that by means
of the apparatus the fine particles are pressed into pellets,
briquettes or corresponding granules such that they stay intact in
the coking reaction without being exposed to the pyrolysis gas and
are led to the quenching zone for increasing the amount of syngas
in order to both cool the gas and to achieve a suitable chemical
composition (H.sub.2/CO.sub.2).
15. Apparatus according to claim 13, characterized in that with the
apparatus the fine particles are separated from the raw material
flow by screening after drying or by screening before drying from
the wet or partially dried biomass.
16. Apparatus according to claim 13, characterized in that the
apparatus comprises one or more screens, through which a fraction
of 2-20 mm goes into fine particles, and a pellet press, suitable
briquetting device or other corresponding granulating device, the
particle size of pellets or briquettes produced in which is in the
range 6-16 mm in diameter, most preferably 6-8 mm, and the length
is approx. 2-4 times the diameter, and drying, in which the
humidity is 5-15%, most preferably approx. 10%.
17. Apparatus according to claim 13, characterized in that the
apparatus comprises a number of screens, in which fine particles
are separately separated from a different raw material flow, such
as from wood chips and bark chips, into fine particles of their own
for producing pellets and/or briquettes such that in the
gasification process there are preferably 2-5 different fuel feed
bins for separately dispensing raw material and pellets and/or
briquettes made of fine particles suitably proportioned into the
reactor.
18. Method according to claim 2, characterized in that in the
method the fine particles are separated from the raw material flow
by screening after drying or by screening before drying from the
wet or partially dried biomass.
19. Method according to claim 2, characterized in that in the
method a drum dryer is used for drying the fine particles.
20. Method according to claim 3, characterized in that in the
method a drum dryer is used for drying the fine particles.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The object of the invention is a method for pretreating the
fine particles of a biomass for a gasification process to the use
of pellet presses, briquetting devices and/or corresponding
graduating devices for pretreating the fine particles and to an
apparatus for pretreating the fine particles.
[0003] 2. Description of Background Art
[0004] Prior art includes different solutions with which biomass is
gasified. For example, a gasification technique of biomass is known
in the art, in which technique the biomass to be gasified is led
into a coking reactor (i.e. low temperature gasifier) after
chipping and drying. The coking reactor operates at a pressure of
1-20 bar, typically at a pressure of 5 bar, and at a temperature of
400-500.degree. C. For coking the biomass, a gas compound
(gasifying agent) is led into the reactor, which compound is
typically a mixture of oxygen and carbon dioxide. Steam can also be
used as a component of the gas compound. When the gas compound and
biomass react, pyrolysis gas and coke are produced in the reactor.
Pyrolysis gases can be further gasified in a high-temperature
gasifier. Pyrolysis gases contain hydrocarbon chains, i.e. also
tar, for which reason the gas pipe to the high-temperature gasifier
is insulated so that condensation of tars is prevented.
[0005] Pyrolysis gas is led to the high-temperature part of the
gasifier, in which it reacts with oxygen typically at a temperature
of approx. 1400.degree. C., in which case the hydrocarbon chains
break down completely, forming carbon monoxide (CO), carbon dioxide
(CO.sub.2), hydrogen (H.sub.2) and steam (H.sub.2O) and small
amounts of other gases, such as hydrogen sulphide (H.sub.2S). The
hot gases flowing downwards are led via a reversal chamber to the
rising reactor part of the gasifier, i.e. to the quenching zone, in
which the cooling of hot gases occurs. In other words, quenching in
this context refers to the cooling of gas that occurs relatively
quickly and in a controlled manner. To achieve a controlled
process, the coke (=carbon) that is received from the coking
reactor and crushed into suitable particle sizes is fed to the
quenching zone. The coke and hot exhaust gases react
endothermically (absorbing heat) with each other, in which case the
gas cools to <900.degree. C., the amount of syngas (H.sub.2 and
CO) maximizes, the amount of carbon dioxide minimizes and a
suitable H.sub.2/CO ratio for syngas applications is produced.
C+CO.sub.2=2CO +162 MJ/kmol
C+H.sub.2O=CO+H.sub.2 +119 MJ/kmol
[0006] Prior-art solutions have a number of drawbacks, e.g. the
biofuel to be fed in has not contained the appropriate particle
size of fuel required by the process, but instead there have been
too many fine particles and in this way the operation of the
process has suffered. The biofuel to be fed in must contain
suitable particle sizes so that the ratio of the pyrolysis gas to
the carbon (coke) used in the quenching remains suitable. If there
are too many fine particles, too much pyrolysis gas is generated
and fine particles are further swept along with the pyrolysis gas
into the high-temperature gasifier. In this case there is not
enough coke for chemical quenching, as a result of which the
quality of the syngas generated deteriorates and the overall
efficiency ratio of the process decreases. Too low an amount of
carbon (coke) in relation to the amount of gas of the gasification
reactor also results in the amount of reactions absorbing heat
decreasing and the gas exiting from the gasifier too hot, in which
case it cannot be further cooled with conventional heat exchangers,
but instead special solutions are required.
SUMMARY AND OBJECTS OF THE INVENTION
[0007] In order to succeed the quenching process requires a certain
residence time for the coke in the reactor and this is achieved by
feeding coke that is crushed into appropriate particle sizes into
the reactor. In FIG. 1 the material left over in quenching goes to
the HTG part via the dust removal of raw gas. If the coke fed to
quenching is too fine, the reactions do not occur in a desired
manner.
[0008] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings, which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0010] FIG. 1 is a schematic view illustrating that the material
left over and quenching goes to the HTG part via the dust removal
of raw gas;
[0011] FIG. 2 is a graft illustrating the cumulative percentage as
compared to size distribution; and
[0012] FIG. 3 is a flow chart illustrating a method according to
the invention wherein the fine particles of the biomass are
granulated by means of pellet presses or suitable briquetting
devices.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Owing to this, according to the specifications of equipment
manufacturers, raw wood material with a particle size of <3 mm
can account for at most 5% of the mass. This is taking into account
and knowing that potential raw materials of biomass, such as
logging residue chips (logging residue chips refer to branches and
top refuse) and also whole tree chips (whole tree chips refer to
chips made of complete trees including tree trunks and branches)
include a lot of small branches, needles and leaves.
[0014] According to FIG. 2, this type of raw material comprises a
lot of fine particles; material of <3 mm can account for even
>30% in a typical particle size distribution. In stem chips made
of stemwood, however, the particle size is close to the
requirements of the equipment manufacturer.
[0015] Bark chips generated as a by-product in the pulp industry,
paper industry and sawmill industry vary in terms of their
properties. The fine particle content of bark chips is in the best
case suited to the gasification process, but in order to increase
the particle size the chips must often be treated with the method
according to the invention. The same applies to the by-products of
the wood processing industry, such as sawdust, screening chips and
cutter chips. They are not applicable, as such, as the raw material
of the gasification process, but instead they must be granulated,
i.e. pelletized or briquetted, with the method according to the
invention in order to increase the particle size. Likewise, milled
peat is very fine and using it without the aforementioned
granulation is not possible in this type of process.
[0016] According to what is presented in the preceding, the aim of
this invention is to achieve a new type of solution. In this way
prior-art problems can be avoided.
[0017] The essential features of the invention significantly affect
the method and the apparatus utilizing said method, and also the
use of said apparatus, which features are defined in the
claims.
[0018] Now with the solution according to the invention, the
gasification process can be more efficiently utilized and at the
same time the operation of the apparatus can be optimized. The
inventiveness of the apparatus is particularly based on
granulating, i.e. pelletizing and/or briquetting, the fine
particles impeding the process with the method according to the
invention in order to increase the particle size. What is
particularly essential to the invention is to utilize the use of
pellet presses or suitable briquetting devices for pretreating the
fine particles of a biomass for the purpose of gasification.
[0019] With the solution according to the invention, the fine
particles of a biomass can now be utilized considerably more
efficiently, and also by pretreating said fine particles better
syngas is produced.
[0020] The invention relates to a method for pretreating the fine
particles of a biomass. What is essential in the method is that,
for pretreating the fine particles for the gasification, the fine
particles are granulated by means of pellet presses or suitable
briquetting devices such that their particle size is advantageous
in coking and quenching.
[0021] What is important in the method is that fine particles are
pretreated into pellets or briquettes such that they stay intact in
the coking reactor without being exposed to the pyrolysis gas. And
in this way increasing the optimal size of the particles to be led
to the quenching zone in the method for improving the efficiency
ratio of the syngas.
[0022] The method according to the invention can be implemented, if
necessary, in two ways. Either such that in the method fine
particles are separated from the raw material flow after drying or
alternatively already before drying from the wet or partially dried
biomass. According to the process, after the drying, the fine
particles to be pelletized are separated from the raw material flow
by screening. The separated coarse material can be transported
directly to the fuel feed bin of the gasifier and the fine particle
flow can be pelletized in its entirety after drying.
[0023] In the second implementation method the screening is
performed on the wet or partially dried biomass. One advantage in
this method is that the fine particles and the coarse material can,
if necessary, be dried using different drying parameters and
possibly different dryer apparatuses because coarse material dries
more slowly than fine particles. A drum dryer can in this case be
used for drying the fine particles while the coarse material is
best suited for drying by a belt dryer. One drawback in this
implementation method is, however, that when screening wet, the
fine particles tend to adhere to the coarse material and the
separating capacity in screening deteriorates and the drying
process becomes more complex. In short, due to this, the
implementation methods vary depending on the process.
[0024] According to FIG. 3, what is essential in the method
according to the invention is that the fine particles of the
biomass are granulated by means of pellet presses or suitable
briquetting devices such that their particle size is in accordance
with the requirements of the gasifier manufacturer. Fine particles
are ground into suitable particle size for pelletizing and fed to
the pellet press via a carry-over stock. In the method fractions
that go through a 2-20 mm screen are used as fine particles. A
preferred particle size in quenching is in the range 2-10 mm and
the particle size of a pellet or briquette produced with a pellet
press is typically in the range 6-16 mm in diameter and the length
approx. 2-4 times the diameter.
[0025] Fuel must often be dried to a suitable humidity of 10-15%
for the gasification. At the same time it is known that wood and
peat-based materials pelletize at the corresponding suitable
humidity of 5-15%, most preferably of approx. 10%, so this is
preferred humidity also from the point of view of the gasification
process.
[0026] In the method pellets and/or briquettes are made most
preferably of peat, logging residue chips, bark chips or
by-products of the wood processing industry, such as sawdust,
screening chips and cutter chips, or field biomass such as reed
canary grass or straw. Fine particles are separately separated from
the wood chips and bark chips into a raw material flow of their own
for producing pellets and/or briquettes. The pellets and/or
briquettes used in the method are produced most preferably from one
raw material as separate clean fine particles, alternatively mixed
pellets or briquettes can also be made of them as a mixture of one
or more different type(s) of fine particles. In this way 2-5
different fuel feed bins are available in the gasification process,
from which bins raw materials, i.e. wood chips, chippings and
pellets, can be dispensed suitably proportioned into the coking
reactor.
[0027] Test runs have additionally been performed with the solution
according to the invention; in the examples the pellets made of
peat stayed intact very well during coking and even the pellets
made of logging residue chips/bark fully sufficiently. Wood pellets
were produced with a small-scale test equipment--i.e. the
mechanical properties of pellets can still be improved by
optimizing the process.
[0028] In addition to the aforementioned method, the invention also
relates to an apparatus for pretreating the fine particles of a
biomass and utilizing said method. The apparatus comprises one or
more pellet presses or suitable briquetting devices for pretreating
the fine particles for the gasification. By means of the apparatus
a suitable particle size of coke is achieved, which particles are
led to quenching in order to produce suitable syngas.
[0029] It is obvious to the person skilled in the art that the
invention is not limited to the embodiments presented above, but
that it can be varied within the scope of the claims presented
below.
[0030] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *