U.S. patent application number 14/427339 was filed with the patent office on 2015-08-27 for apparatus and method for generating fuel gas from a solid combustible.
The applicant listed for this patent is BIG DUTCHMAN INTERNATIONAL GMBH. Invention is credited to Armin Schwarz.
Application Number | 20150240172 14/427339 |
Document ID | / |
Family ID | 49683661 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150240172 |
Kind Code |
A1 |
Schwarz; Armin |
August 27, 2015 |
APPARATUS AND METHOD FOR GENERATING FUEL GAS FROM A SOLID
COMBUSTIBLE
Abstract
The invention relates to a method and an apparatus for
generating fuel gas from a solid material in a shaft gasifier, and
comprises a gasification zone, into which the solid material can be
filled, and an oxidation zone designed to oxidize the generated gas
connected to the gasifier zone so that the gases generated in the
gasifier zone run to the oxidation zone. A first air supply device
and a second air supply device downstream of the first air supply
in the processing direction of the solid material supply air into
the gasification zone. A measurement unit samples the raw gas that
is generated in the oxidation zone or of the flammable product gas.
A control unit, which is coupled with the measurement unit by means
of signal technology, transmits a test signal and controls the air
supplied by the second air supply device via the test signal.
Inventors: |
Schwarz; Armin; (Vechta,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BIG DUTCHMAN INTERNATIONAL GMBH |
Vechta |
|
DE |
|
|
Family ID: |
49683661 |
Appl. No.: |
14/427339 |
Filed: |
September 13, 2013 |
PCT Filed: |
September 13, 2013 |
PCT NO: |
PCT/EP2013/002765 |
371 Date: |
March 11, 2015 |
Current U.S.
Class: |
48/86R ;
48/197FM; 48/209 |
Current CPC
Class: |
C10J 3/723 20130101;
C10J 3/725 20130101; C10J 3/82 20130101; C10J 2300/1846 20130101;
C10J 2300/1618 20130101; C10J 2300/0916 20130101; C10J 2300/0956
20130101; C10J 2300/092 20130101; C10J 2300/1207 20130101; C10J
3/64 20130101; C10J 2200/15 20130101; C10J 2300/1609 20130101; C10J
3/26 20130101; C10J 2200/152 20130101; C10J 3/06 20130101 |
International
Class: |
C10J 3/72 20060101
C10J003/72; C10J 3/82 20060101 C10J003/82 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2012 |
DE |
20 2012 008 777.0 |
Claims
1-17. (canceled)
18. A gasification apparatus for generating a combustible product
gas from a solid material, comprising: a gasification zone, into
which the solid material can be filled via a solid material filler
inlet, and from which solid material a pyrolysis gas is generated;
an oxidation zone for the oxidation of the generated pyrolysis gas,
which is connected to the gasification zone in order to run the
pyrolysis gas generated in the gasification zone into the oxidation
zone; and wherein a first air supply device and a second air supply
device supply air into the gasification zone, wherein the second
air supply device follows the first air supply device in the
processing direction of the solid material; a measurement unit for
determining a qualitative or quantitative quantity of predetermined
gas components of the flammable product gas, and from which
generates test signals; and a control unit, which is coupled with
the measurement unit by means of signal technology in order to
transmit the test signals, and which is configured in such a way
that the control unit controls the quantity of the air being
supplied by the first and/or second air supply devices as a
function of the test signals.
19. The gasification apparatus according to claim 18, wherein the
gasification zone and the oxidation zone are in thermal contact,
wherein either the oxidation zone encloses the gasification zone in
a cross section of the shaft gasifier in the direction of material
flow of the solid material, or the gasification zone encloses the
oxidation zone in a cross section of the shaft gasifier in the
direction of material flow of the solid material, and wherein the
gasification zone is preferably subdivided into a plurality of
gasification sectors each having individually controllable air
supply, which zones are regularly or irregularly distributed across
the cross section.
20. The gasification apparatus according to claim 18, wherein in an
operating position in the direction of gravity, the gasification
zone is disposed below a solid material filler inlet for the
filling of solid material under the effect of gravity.
21. The gasification apparatus according to claim 18, further
comprising a reduction zone, which is connected to the oxidation
zone in order that the raw gas formed in the oxidation zone be
supplied to said reduction zone, and which is designed to
chemically reduce the raw gas supplied thereto.
22. The gasification apparatus according to claim 21, wherein the
reduction zone is disposed below the gasification zone in the
direction of gravity and is connected thereto for the direct
transfer of solid material under the effect of gravity from the
gasification zone into the reduction zone, and a section of the
oxidation zone is disposed to separate the gasification zone from
the reduction zone in the direction of flow of the gas that is
generated.
23. The gasification apparatus according to claim 18, wherein the
measurement unit directly or indirectly measures the tar content of
the raw gas or of the product gas that is generated, and wherein
the control unit controls the quantity of air that is supplied via
the second air supply device as a function of the tar content of
the raw gas or of the product gas that is generated.
24. The gasification apparatus according to claim 23, wherein the
measurement unit is a CH.sub.4 sensor, which is configured to
convey indirect information concerning the tar component of the raw
gas or the product gas via processing by means of signal
technology.
25. The gasification apparatus according to claim 21, wherein the
measurement unit is designed in such a way that it directly or
indirectly measures the CO content of the product gas that is
generated, and in that the control unit controls the quantity of
the air supplied by the second air supply device as a function of
the CO content of the product gas that is generated in response to
the measurement unit.
26. The gasification apparatus according to claim 25, wherein the
second air supply device is located directly above the transition
from the gasification zone into the reduction zone.
27. The gasification apparatus according to claim 18, further
comprising a gas extraction device, which has a suction opening
located to the side on the gasification apparatus, and wherein the
gas extraction device comprises a suction ring, which is configured
such that it generates a uniform speed distribution across the
cross section of the gasification apparatus for the gas being
extracted, in that the ring provides the gas with a large outlet
cross section on the side facing away from the outlet opening, and
which tapers on the side facing the outlet opening.
28. A gasification method for generating a combustible product gas
from a solid material, comprising the steps of: supplying a solid
material into a gasification zone; gasification of the solid
material in the gasification zone by means of pyrolysis or
gasification to generate a pyrolysis gas; supplying the pyrolysis
gas that is generated in the gasification zone to an oxidation
zone; supplying air into a gasification zone through a first air
supply device; and positioning a second air supply device
downstream from the first air supply device in a processing
direction of the solid material, wherein the supply of air via the
second air supply device is controlled as a function of a
measurement of the qualitative or quantitative quantity of a
predetermined component of the gas in the raw gas that is generated
in the oxidation zone or in a combustible product gas.
29. The method of gasification according to claim 28, wherein the
supply of air into the gasification zone is individually controlled
within one or more gasification sectors that are either regularly
or irregularly distributed across a cross section of the
gasification zone.
30. The method of gasification according to claim 28, further
comprising the steps of: supplying air into the oxidation zone and
conversion of the pyrolysis gas in a stoichiometric process by
means of partial oxidation and cracking into a raw gas in the
oxidation zone; supplying raw gas from the oxidation zone into a
reduction zone; supplying partially or completely pyrolyzed solid
material into the reduction zone; and chemically reducing the raw
gas in the reduction zone by means of the pyrolyzed solid material
into the combustible product gas.
31. The method of gasification according to claim 28, wherein a tar
content in the raw gas or product gas that is generated is measured
directly or indirectly, and the quantity of air supplied via the
second air supply device is supplied as a function of one or more
test signals which are processed by means of signal technology.
32. The method of gasification according to claim 31, wherein the
CH.sub.4 content of the product gas that is generated is measured
to draw direct or indirect conclusions concerning the tar content
of the raw gas or product gas via signal technology processing and
controlling the supply of aid from the second air supply device as
a function of this measurement.
33. The method of gasification according to claim 30, wherein the
CO content of the product gas that is generated in the reduction
zone is measured, and the quantity of air that is supplied by the
second air supply device is controlled as a function of the
detected CO content.
34. The method of gasification according to claim 28, further
comprising: extraction of combustible gases using a gas extraction
device, which has a suction opening located to the side on the
gasification apparatus, and which is configured in such a way that
it generates a uniform speed distribution across the cross section
of a gasification apparatus for the gas being extracted, and
wherein the gas extraction device has a suction ring, which
provides the gas with a large outlet cross section on the side
facing away from the outlet opening, and which tapers on the side
facing the outlet opening.
Description
CROSS-REFERENCE TO FOREIGN PRIORITY APPLICATION
[0001] The present application claims the benefit under 35 U.S.C.
.sctn.119(b) of PCT/EP2013/002765, filed Sep. 13, 2013, which
claims priority to German Application 202012008777.0, filed Sep.
13, 2012, entitled "Apparatus for Generating Fuel Gas From a Solid
Combustible."
[0002] The invention relates to an apparatus and method for
generating fuel gas from a solid material in a shaft gasifier, and
comprises a gasification zone, into which the solid material can be
filled via a filler inlet, and an oxidation zone designed to
oxidize the generated gas, which oxidation zone is connected to the
gasifier zone so that the gases generated in the gasifier zone can
be run to the oxidation zone. A further aspect of the invention is
a gasification process for generating a combustible gas from a
solid material.
FIELD OF THE INVENTION
[0003] Gasification apparatus of the aforementioned type and
gasification processes are used to gasify solid substances, such as
organic or inorganic, carbonaceous materials, especially wood,
plant, or plant remains, as completely as possible in a controlled
process in order to thereby generate an ignitable and, in
particular, a flammable gas. Typically, the gas thus generated is
burned in a process that is downstream from the gasification in
order to thereby perform work and, for example, operate a power
generator.
[0004] A gasifier and a method of gasification are known from EP 1
865 046 A1, which generate a pyrolysis gas by gasifying the solid
material in a shaft gasifier in a three-stage process, which
pyrolysis gas is then converted into a raw gas through partial
oxidation and thermal breakdown, and converted into a combustible
product gas through a process of reduction. In the prior art
disclosed in this patent application, the gasification is at times
incomplete, in particular in the case of changing properties of the
solid material, so that the amount of energy available in the solid
material is not fully utilized.
[0005] An adjustment and/or monitoring of the quality, especially
of the first process, of the gasification by recording the
temperature by means of measurement technology, but also through
the selection of the specific gas composition and adjusting the
supplied air for the gasification process is known from EP 1 865
046 A1. The optimization potential in the case of shaft gasifiers
having a multi-stage process chain often lies in the quality/purity
of the product gas that is ultimately generated, which is decisive
for the subsequent combustion, the need for additional filters, and
which is indirectly decisive in terms of the maintenance intensity
for the shaft gasifier. A reduction in efficiency may occur as a
result of almost unavoidable gas leakage from the gasification zone
into the reduction zone, or as a result of changes in the
properties of the solid material that is to be gasified during the
gasification process.
[0006] The object of the present invention is therefore to provide
a gasifier and a method of gasification which achieves an efficient
gasification of a solid material, and which thereby ensures
increased purity of the product gas.
SUMMARY OF THE INVENTION
[0007] This object is achieved according to the invention in that
the shaft gasifier is refined according to the invention in such a
way that a first air supply device and a second air supply device
feed air into the gasification zone, wherein the second air supply
device is positioned downstream from the first air supply device in
the processing direction of the solid material. A measurement unit
for detecting a test signal is designed to determine a qualitative
or quantitative quantity of predetermined gas components of the raw
gas that is generated in the oxidation zone or of the flammable
product gas, and which characterizes this in the test signal. A
control unit is coupled with the measurement unit by means of
signal technology in order to transmit test signal, and is
configured in such a way that said control unit controls the
quantity of the air being supplied by the second air supply device
as a function of the test signal.
[0008] The first and second air supply device can supply air to the
gasification zone as needed and independent of one another. The
measurement device measures the qualitative or quantitative
quantity of a predetermined portion of a gas. Here, gas is
understood both as a substance, which consists of a chemical
element or a chemical compound in a gaseous state (e.g., oxygen,
methane, carbon monoxide, etc.), and also as a gas mixture
consisting of a plurality of substances (e.g., air). The control
unit, which is coupled with the measurement device by means of
signal technology, is then able to adjust the air supplied by the
second air supply device as a function of the measurement results.
The second air supply device thereby is positioned downstream from
the first air supply device in the processing direction, since the
control of the second air supply device is in response to the
already ongoing processes in the gasification zone.
[0009] According to the invention, the supply of air in a
predetermined level of the gasification zone can be optimized
through the qualitative or quantitative quantity of a predetermined
gas, which is detected by means of measurement technology, at a
selected stage of the gasification process, and it becomes possible
to react flexibly to changes in the characteristic properties of
the process products while the process chain is ongoing. According
to the invention, it was recognized that in this way, a loss of
efficiency with respect to the purity of the generated gas, which
is caused by an unwanted transfer of generated process materials
from the gasification zone into the reduction zone can be
prevented. While conventional apparatus and methods are often
geared towards preventing the nearly unavoidable transfer of
pyrolysis gas from the gasification zone directly into the
reduction zone as much as possible, and forcing a path via the
oxidation zone, the present invention solves the problem in that
the leaked gases that arise are oxidized directly in the
gasification zone by supplying air from a second air supply device.
The quantity of air from the second air supply device needed is
controlled as needed. This is done according to the invention with
the help of the measurement device, which directly or indirectly
measures the tar content of the raw gas or, respectively, product
gas that is generated and, based on the measured values, provides
information concerning the level of contamination by non-oxidized
pyrolysis gas. The control device, which is connected by means of
signal technology, adjusts the supply of air as a function of said
measured values.
[0010] In the case of the gasification apparatus refined according
to the invention, a measurement device and processing by means of
signal technology are provided, which makes it possible to draw
conclusions regarding the concentration of the leaked gases on the
basis of the tar content. In order to reliably oxidize these leaked
gases in the gasification zone, the supply of air from the second
air supply device can be adjusted as a function of the measured
values received via the control unit, which is connected by means
of signal technology. In the case of increased tar content in the
raw gas that is generated, the supply of air from the second air
supply device is increased, while that air supply can be decreased
in the event that a measurable tar content is low or is absent.
[0011] According to the invention, the measurement unit may also be
configured such that it directly or indirectly measures CO content
of the product gas that is generated, and the quantity of air that
is supplied via the second air supply device can be adapted with
the aid of a control unit that is connected by means of signal
technology as a function of the measured value that has been
processed by means of signal technology.
[0012] Like the tar content, in the case of the gasification
apparatus thus refined according to the invention, the detected CO
content provides information regarding the efficiency of the
respectively desired conversion process. The latter is at its
highest in the reduction zone when the raw gas from the oxidation
zone and the pyrolyzed solid coke from the gasification zone are as
hot as possible when they converge, ideally at approximately
1000.degree. C. On the basis of the CO content of the product gas
ultimately obtained that has been detected by means of measurement
technology, the supply of air can be adjusted by means of
processing by means of signal technology by the control unit, which
is connected by means of signal technology, in such a way that the
coke is once again heated as much as possible before it enters the
reduction zone.
[0013] According to the invention, the air supply devices can each
be used individually, but can also be used in combination with one
another. In a preferred embodiment, preceding filtering and/or
cooling of the gas may occur prior to the measurement of the gas
components in the product gas.
[0014] A gasification of a solid material in a large gasification
zone is achieved by means of the gasification apparatus refined
according to the invention, without the occurrence thereby of an
unwanted transfer of the product materials generated, for example
non-oxidized raw gas, as leaked gases, or insufficiently heated
coke.
[0015] The oxidation zone is connected to the gasification zone in
order to run the pyrolysis gas that is generated in the
gasification zone into the oxidation zone. The gasification zone
and the oxidation zone are preferably separated from one another by
at least one wall. The connection of the oxidation zone to the
gasification zone in order to run the pyrolysis gas that is
generated in the gasification zone into the oxidation zone can
preferably be created by means of a connection created by means of
fluid technology in specific sections, for example by means of one
or a plurality of openings in the wall. The process flow of the
gasification can be improved by such a design of the gasification
apparatus, in particular by such a spatial separation of the
gasification zone and the oxidation zone.
[0016] In addition, it is preferred that the wall have openings
that face obliquely downward, located in an upper part of said wall
when in an operating position, via which openings the pyrolysis gas
that arises in the gasification zone passes into the oxidation zone
as a result of the pressure and flow conditions. The openings are
preferably formed in that the sloped wall ends at the height of the
respective opening, and is continued just above said opening, being
displaced radially inwardly. The thus slightly overlapping,
obliquely descending walls of the oxidation zone can thus prevent
the unwanted inflow of the solid material into the oxidation zone
or a blockage of the opening by the carried solid material.
[0017] It is especially preferred that the gasification zone and
the oxidation zone be in thermal contact, preferably via the at
least one wall, which separates the gasification zone and the
oxidation zone from one another. This enables a particularly
advantageous utilization of the process heat that is created.
[0018] It is provided by means of a first preferred embodiment
that, in terms of its cross section, the oxidation zone is at least
partially, preferably completely enclosed by the gasification zone.
According to this embodiment, the oxidation zone is centrally
disposed within the gasification apparatus, in which, in terms of a
cross section through the gasification apparatus, said oxidation
zone is at least partially, but preferably completely enclosed by
the gasification zone. In this way, in particular an annular
gasification zone is formed around the oxidation zone, thereby
allowing for an effective heat transfer from the gasification zone
into the oxidation zone and vice versa. At the same time, it is to
be understood that on the one hand, a convective heat transport
takes place as a result of the supply of pyrolysis gas from the
gasification zone into the oxidation zone, however, in addition,
heat transport can also take place through a direct heat transfer
as a result of the fact that the oxidation zone is enclosed by the
gasification zone. In particular, this embodiment may be
implemented such that the gasification apparatus is designed as a
shaft gasifier, and such that the oxidation zone is designed as an
oxidation chamber that is centrally disposed within the shaft
gasifier, said oxidation chamber being enclosed by an annular
gasification zone.
[0019] In a further preferred embodiment, a temperature measuring
unit thereby measures the temperature in or in the immediate
vicinity of the oxidation chamber. On the basis of the measurement
results processed by means of signal technology, the supply of air
into the gasification zone can be adjusted, preferably via the
first air supply device so that preferably, a temperature of
approximately 1000.degree. C. prevails in the oxidation zone.
[0020] Moreover, it is preferred that the solid material can be
supplied to the gasification zone in an operating position through
a solid material filler inlet solely through the use of
gravity.
[0021] With an embodiment thus designed, it is possible to achieve
an efficient and robust supply of solid material, since there are
no mechanical feeders that could disrupt the process in the event
of a malfunction.
[0022] In addition, it is preferred that the gasification apparatus
according to the invention be further refined by a reduction zone,
which is connected to the oxidation zone in order that the raw gas
formed in the oxidation zone be supplied to said reduction zone,
and which is designed to chemically reduce the raw gas supplied
thereto. In the reduction zone, a fuel gas can be generated from
the pyrolysis gas prepared in the oxidation zone, in particular
with the help of coke, which is transported from the gasification
zone into the reduction zone, and which is composed of degassed
solid residues. In so doing, a filtration of solid particles
through the coke in the reduction zone can also be achieved.
Alternatively, or in addition to this, other filtering processes
may also be provided, for example by means of candle filters or the
like.
[0023] In addition, it is preferred that the reduction zone having
the above or previously explained design be disposed below the
gasification zone in the direction of gravity so that said zones
are directly connected, and the solid material can pass directly
from the gasification zone into the reduction zone under the effect
of gravity. In so doing, a section of the oxidation zone should
preferably be designed such that said section separates the
gasification zone from the reduction zone in the direction of flow
of the gas that is generated. As explained above, a fuel gas can be
generated from the pyrolyzed and oxidized or, respectively, cracked
raw gas from the oxidation zone and, in so doing, an additional
filter effect can be achieved in this reduction zone.
[0024] A CH.sub.4 sensor represents a preferred implementation of
the measurement unit for determining the tar content in the raw gas
or, respectively, the product gas that is generated, which CH.sub.4
sensor provides indirect information concerning the tar content
contained in the gas via the CH.sub.4 content detected, and which
thus be used via processing by means of signal technology in order
to adjust the supply of air in the second air supply level.
[0025] The pyrolysis gas that is created during the gasification of
the solid material is a mixture of carbon monoxide (CO), hydrogen
(H.sub.2), water vapor (H.sub.2O), carbon dioxide (CO.sub.2),
methane (CH.sub.4) as well as a series of trace gases and
impurities in the form of long-chain hydrocarbons (tar). The easily
combustible components are oxidized in the subsequent partial
oxidation in the oxidation zone. This is an exothermic reaction,
and thus the temperature is increased. This temperature can be
adjusted to approximately 1,000.degree. C., wherein non-oxidized,
long-chain hydrocarbons (tar) break down into short-chain molecules
(cracking). During combustion in the oxidation chamber, typical
products of combustion such as H.sub.2O and CO.sub.2 are created
during the partial oxidation of the easily combustible components.
These gases are endothermically converted into H.sub.2 and CO in
the reduction zone when they encounter the coke created in the
gasification zone. In so doing, the temperature falls, since
thermal energy is converted into chemical energy. Non-oxidized and
leaked gases that have not been cracked, which circumvent the
oxidation chamber, flow through the reduction zone without being
involved in the endothermic reactions. They are subsequently found
in the finished product gas. The concentration of these impurities
can be determined by measuring the CH.sub.4 (methane) content in
the product gas.
[0026] In terms of the implementation of the measurement unit for
the determination of the CO content in the product that is
generated, an embodiment is preferred, in which the second air
supply device is disposed directly before the transition from the
gasification zone into the reduction zone.
[0027] A further preferred embodiment provides both an additional
air supply device in the region of the gasification zone in order
to oxidize exiting leaked gases as well as an additional air supply
device directly before the transition from the gasification zone
into the reduction zone in order to optimize the heating of the
coke.
[0028] A further aspect of the invention is a gasification
apparatus of the above-mentioned type, which additionally has a gas
extraction device, which has a suction opening located to the side
on the gasification apparatus, and which is thereby characterized
by the fact that the gas extraction device comprises a suction
ring, which is configured to have a uniform speed distribution
across the cross-section of the gasifier for the gas being
extracted, in that the ring provides the gas with a large outlet
cross-section on the side facing away from the outlet opening and
which tapers on the side facing the outlet opening.
[0029] This aspect of the invention can be implemented in
combination with the preferred embodiments already described
above.
[0030] In a preferred embodiment, the extraction device is located
such that it is annularly disposed about the reduction zone,
wherein the suction ring provides the combustible gas with a large
opening on the side facing away from the outlet opening in the
direction of gravity, which tapers either continuously or in a
stepped manner towards the side facing the outlet opening.
[0031] A further aspect of the invention is a method of
gasification for generating combustible gases from a solid
material, comprising the following steps of supplying solid
material into a gasification zone, and gasification of the solid
material in the gasification zone by means of pyrolysis or,
respectively, gasification supplying of the pyrolysis gas that is
generated in the gasification zone to an oxidation zone supplying
of air to the gasification zone which is characterized in that the
gasification in the gasification zone of air occurs in at least two
air supply device, wherein the second air supply device is
positioned downstream from the first air supply device in the
processing direction of the solid material, and the supply of air
via the second air supply device is controlled as a function of the
measurement of the qualitative or quantitative quantity of
predetermined gases, both pure gases and gas mixtures, in the raw
gas that is generated in the oxidation zone or in the combustible
product gas. The method of gasification according to the invention
may be implemented in particular using the above-described
gasification apparatus and is characterized in that it is possible
to prevent the unwanted emission of process materials from the
gasification zone into the adjacent process zones through the
individually controlled supply of air in various levels of the
gasification zone.
[0032] The method can be further refined in that the supply of air
in the gasification zone is individually controlled for
gasification sectors that are either regularly or irregularly
distributed across the cross-section.
[0033] A further embodiment provides for the following additional
method steps of supplying air into the oxidation zone and
conversion of the pyrolysis gas in a stoichiometric process by
means of partial oxidation and cracking into a raw gas in the
oxidation zone, supplying raw gas from the oxidation zone into a
reduction zone, supplying partially or completely pyrolyzed solid
material into the reduction zone, and reduction of the raw gas in
the reduction zone by means of the pyrolyzed solid material into a
fuel gas.
[0034] In addition, the method of gasification may be further
refined either alternatively or in parallel to the above, such that
the tar content in the raw gas that is generated can be measured,
either directly or indirectly, with the help of the measurement
unit, and/or the CO content in the product gas that is generated
can be measured in a parallel operation with the help of a second
measurement unit, and the supply of air provided via a second air
supply device or, in the parallel use of both measurements, via a
third air supply device can be adapted according to the associated
measurement results, which are processed by means of signal
technology.
[0035] The direct transfer of components of the pyrolysis gas that
is generated without prior oxidation into the reduction zone can be
prevented with the help of the supply of air, which is controlled
as a function of the tar content. The determination of the indirect
tar content can thereby be performed using a CH.sub.4 sensor.
[0036] When supplying air as a function of the CO content,
supplying air immediately before the transition from the
gasification zone into the reduction zone is especially
advantageous, since the pyrolyzed solid coke is once again heated
immediately before entering the reduction zone, and the subsequent
reduction of the raw gas with the help of the coke can progress in
an especially effective manner in this case.
[0037] The method of gasification can be further refined
alternatively or in parallel to the above, in that the method
comprises the step of extracting the combustible gases using a gas
extraction device, wherein the gas extraction device has a suction
opening located to the side on the gasification apparatus, and
configured such that the method is configured to have a uniform
speed distribution across the cross-section of the gasifier for the
gas being extracted, in that the gas extraction device has a ring,
which provides the gas with a large outlet cross section on the
side facing away from the outlet opening, and which tapers on the
side facing the outlet opening.
[0038] The invention will be explained in greater detail below on
the basis of non-limiting examples of preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWING
[0039] FIG. 1 is a longitudinally sectioned side view of a
preferred embodiment of the gasification apparatus according to the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] For purposes of description herein, the terms "upper,"
"lower," "right," "left," "rear," "front," "vertical,"
"horizontal," and derivatives thereof shall relate to the invention
as oriented in FIG. 1. However, it is to be understood that the
invention may assume various alternative orientations and step
sequences, except where expressly specified to the contrary. It is
also to be understood that the specific devices and processes
illustrated in the attached drawings, and described in the
following specification, are simply exemplary embodiments of the
inventive concepts defined in the appended claims. Hence, specific
dimensions and other physical charac-teristics relating to the
embodiments disclosed herein are not to be considered as limiting,
unless the claims expressly state otherwise.
[0041] FIG. 1 shows a preferred embodiment of the present shaft
gasifier 1. The solid material can be supplied to the gasification
zone 2 by means of the solid material filler inlet 9, which
gasification zone encloses the centrally located oxidation zone 3
on all sides in a horizontal cross section. In the case of a
cylindrical embodiment as shown in FIG. 1, this results in an
annular gasification zone, which takes shape about the oxidation
zone, which is separated therefrom by the wall 14 of the oxidation
zone, however, which is in thermal contact thereto in the case of a
corresponding configuration of the wall 14. Air is supplied to the
oxidation zone 3 via an air supply pipe 11, which is enclosed by a
casing pipe 12, and which preferably extends centrally in
longitudinal direction along the middle axis of the gasifier.
However the air supply pipe may also be disposed outside of the
longitudinal axis or laterally, in a radial direction, and may
extend parallel to that longitudinal axis. The oxidation zone
preferably has a bell-shaped configuration, wherein the upper part
13, which slopes downward tapered from the top to the bottom,
facilitates the supply of the solid material into the gasification
zone solely on the basis of gravity.
[0042] In the upper part of the oxidation zone 3, the wall 14 has
openings 15 that face obliquely downward, by means of which
openings the pyrolysis gas that arises in the gasification zone
passes into the oxidation zone as a result of the pressure and flow
conditions. The openings are formed in that the sloped wall ends at
the height of the respective opening, and is continued just above
said opening, being displaced radially inwardly. The thus slightly
overlapping, obliquely descending walls 13 of the oxidation zone
prevent the unwanted inflow of the solid material into the
oxidation zone or a blockage of the opening by the carried solid
material.
[0043] An individually adjustable quantity of air is supplied to
the gasification zone 2 via air nozzles 4, 5, 6, which extend in a
radial direction to the middle axis of the gasifier and which are
distributed at regular or irregular intervals along the
circumference of the shaft gasifier. Air for maintaining the
temperature needed for the processes occurring in the upper part of
the shaft gasifier is injected via the air supply device 4 in the
first level. In so doing, a temperature measurement unit 7 measures
the temperature in or in the immediate vicinity of the oxidation
chamber and the supply of air via the air supply device 4 is
adjusted accordingly on the basis of measurement results that are
processed by means of signal technology so that preferably a
temperature of approximately 1000.degree. C. prevails in the
oxidation zone.
[0044] While the majority of the pyrolysis gas that arises then
passes through the oxidation zone along the provided path, it is
unavoidable that a fraction of said gas penetrates into the
reduction zone 8 directly from the gasification zone. In order to
prevent a contamination of the oxidized pyrolysis gas from thus
occurring, additional air is supplied to the gasification zone with
the help of a second air supply device 5, which is positioned
downstream from the first air supply device 4 when in the
operational position, in order to oxidize the leaked gases directly
in the gasification zone 2. The necessary quantity of air that must
be supplied is determined with the aid of the measurement unit 10,
which directly or indirectly measures the tar content of the
product gas that is generated, and is adjusted via a control unit
that is connected by means of signal technology as a function of
measured values that are processed by means of signal
technology.
[0045] Such oxidation of the leaked gases results in local
temperature increases in the pyrolyzed solid material, the coke,
which is to reduce the oxidized pyrolysis gas in the reduction zone
by means of an endothermic reaction such that a preceding
temperature increase has an entirely positive effect. In order to
be able to adjust the temperature of the coke independently of the
quantity of air injected in the second air supply level, either
without preceding oxidation of leaked gases via a second air supply
device or, as indicated in FIG. 1, in addition thereto, air is
injected into the gasification zone via an additional air supply
device 6 immediately before the coke is transferred from the
gasification zone 2 into the reduction zone 8 so that the oxidized
pyrolysis gas and the coke converge in the reduction zone at
preferably 1000.degree. C. A measurement of the CO content on the
final product gas can provide information concerning the efficiency
of the reduction process. The measurement unit 10 either directly
or indirectly measures the CO content of the product gas so that,
by processing the measured values by means of signal technology,
the control unit can adjust the supply of air from the third air
supply device 6 as a function of the measurement results
obtained.
[0046] In the lower part of the gasifying apparatus depicted in
FIG. 1, the gas that is generated is extracted via an outlet
opening 16. In order to obtain a uniform speed of the gas that is
generated across the cross section of the gasifier, a suction ring
17, which encloses the reduction zone, is configured in such a way
the ring has the largest outlet cross section 18 on the side facing
the outlet opening, which tapers as it approaches the outlet
opening so that the side directly in front of the outlet opening
provides the smallest outlet cross section.
[0047] It is to be understood that variations and modifications can
be made on the aforementioned structure and method without
departing from the concepts of the present invention, and further
it is to be understood that such concepts are intended to be
covered by the following claims unless these claims by their
language expressly state otherwise.
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