U.S. patent application number 15/123316 was filed with the patent office on 2017-03-16 for gasification system.
This patent application is currently assigned to THE CHUGOKU ELECTRIC POWER CO., INC.. The applicant listed for this patent is THE CHUGOKU ELECTRIC POWER CO., INC., HIROSHIMA UNIVERSITY, TOYO KOATSU CO., LTD.. Invention is credited to Yoshifumi Kawai, Haruhito Kubota, Yukihiko Matsumura, Takashi Noguchi, Keiji Oyama, Ichiro Uchiyama, Yasutaka Wada, Yukimasa Yamamura, Toshiki Yamasaki.
Application Number | 20170073594 15/123316 |
Document ID | / |
Family ID | 54054755 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170073594 |
Kind Code |
A1 |
Wada; Yasutaka ; et
al. |
March 16, 2017 |
GASIFICATION SYSTEM
Abstract
A gasification system includes a countercurrent type heat
exchanger that includes a low-temperature side flow channel through
which a gasification feedstock flows, and a high-temperature side
flow channel to which treated water in a supercritical state is
introduced. The treated water raises a temperature of the
gasification feedstock by exchanging heat with the gasification
feedstock. The system further includes a reactor that gasifies the
gasification feedstock, whose temperature has been raised by the
countercurrent type heat exchanger, by heating and pressurizing the
gasification feedstock to be in a supercritical state. The reactor
discharges the gasification feedstock as treated water in the
supercritical state. The system further includes a treated water
flow channel that introduces, to the countercurrent type heat
exchanger, the treated water that has been discharged from the
reactor, and a feedstock introduction port that introduces the
feedstock to the low-temperature side flow channel.
Inventors: |
Wada; Yasutaka; (Hiroshima,
JP) ; Kubota; Haruhito; (Hiroshima, JP) ;
Yamamura; Yukimasa; (Hiroshima, JP) ; Uchiyama;
Ichiro; (Hiroshima, JP) ; Oyama; Keiji;
(Hiroshima, JP) ; Yamasaki; Toshiki; (Hiroshima,
JP) ; Matsumura; Yukihiko; (Hiroshima, JP) ;
Kawai; Yoshifumi; (Hiroshima, JP) ; Noguchi;
Takashi; (Hiroshima, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE CHUGOKU ELECTRIC POWER CO., INC.
HIROSHIMA UNIVERSITY
TOYO KOATSU CO., LTD. |
Hiroshima
Hiroshima
Hiroshima |
|
JP
JP
JP |
|
|
Assignee: |
THE CHUGOKU ELECTRIC POWER CO.,
INC.
Hiroshima
JP
HIROSHIMA UNIVERSITY
Hiroshima
JP
TOYO KOATSU CO., LTD.
Hiroshima
JP
|
Family ID: |
54054755 |
Appl. No.: |
15/123316 |
Filed: |
March 5, 2014 |
PCT Filed: |
March 5, 2014 |
PCT NO: |
PCT/JP2014/055692 |
371 Date: |
September 2, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10J 2300/0906 20130101;
C10J 3/86 20130101; C10J 2300/0979 20130101; C10J 2300/1861
20130101; C10J 2300/1246 20130101; Y02P 20/54 20151101; C10J 3/76
20130101; Y02P 20/124 20151101; F28F 2250/06 20130101; Y02P 20/544
20151101; C10J 2300/0916 20130101; C10J 3/78 20130101; F28D 7/14
20130101; Y02P 20/10 20151101; C10J 2300/1892 20130101 |
International
Class: |
C10J 3/76 20060101
C10J003/76; C10J 3/86 20060101 C10J003/86 |
Claims
1. A gasification system comprising: a countercurrent type heat
exchanger that includes a low-temperature side flow channel through
which a gasification feedstock flows, and a high-temperature side
flow channel to which treated water in a supercritical state is
introduced, wherein the treated water raises a temperature of the
gasification feedstock by exchanging heat with the gasification
feedstock; a gasification reactor that gasifies the gasification
feedstock, whose temperature has been raised by the countercurrent
type heat exchanger, by heating and pressurizing the gasification
feedstock to be in a supercritical state, wherein the gasification
reactor discharges the gasification feedstock as treated water in
the supercritical state; a treated water flow channel that
introduces, to the countercurrent type heat exchanger, the treated
water that has been discharged from the gasification reactor; a
feedstock introduction port that introduces the gasification
feedstock to the low-temperature side flow channel; and an external
heater that extracts, from the middle of the low-temperature side
flow channel, the gasification feedstock that has been introduced
by the feedstock introduction port, heats an extracted gasification
feedstock, and returns a heated gasification feedstock to a middle
position on a feedstock downstream side of a position in which the
gasification feedstock has been extracted.
2. The gasification system according to claim 1, wherein a position
in which the extraction is performed is determined based on a value
of specific heat at constant pressure of the gasification
feedstock, and the gasification feedstock is extracted from the
position that has been determined.
3. The gasification system according to claim 1, wherein specific
heat at constant pressure of the water at the position in which the
extraction is performed is 10 kJ/kgK or greater.
4. The gasification system according to claim 1, wherein the
low-temperature side flow channel includes a low-temperature zone
in which a temperature of the gasification feedstock introduced by
the feedstock introduction port is raised, and a high-temperature
zone in which a temperature of the gasification feedstock that has
passed through the low-temperature zone is raised again, and the
external heater extracts the gasification feedstock from a high
temperature end of the low-temperature zone and returns the
gasification feedstock to a low temperature end of the
high-temperature zone.
5. The gasification system according to claim 1, wherein heating by
the external heater is performed in a preheater that preheats the
gasification feedstock whose temperature has been raised by the
countercurrent type heat exchanger.
Description
TECHNICAL FIELD
[0001] One or more embodiments of the invention relate to a
gasification system for gasifying gasification feedstocks such as
biomass by using a heat exchanger.
BACKGROUND ART
[0002] As a system for gasifying feedstocks such as biomass (Shochu
(distilled liquor) residue, egg-laying hen droppings and the like)
by using a heat exchanger, Patent Literatures 1 and 2 disclose
techniques that raise the temperature of water-containing biomass
by exchanging heat with supercritical water in a double-pipe heat
exchanger and gasify the biomass by heating the biomass by a
predetermined reactor and burner.
CITATION LIST
Patent Literature
[0003] PTL 1: Japanese Patent No. 4719864
[0004] PTL 2: Japanese Patent No. 4997546
SUMMARY OF THE INVENTION
[0005] In each of heat exchangers of Patent Literatures 1 and 2,
the temperature of a suspension including biomass is raised from
room temperature to a high temperature of, for example, about
400.degree. C. Further, an internal pressure of the heat exchanger
is high such as 25 MPa at this time.
[0006] However, in such a high-temperature and high pressure,
specific heat at constant pressure of water (suspension) becomes
large, and thus heat exchange efficiency in the heat exchanger is
deteriorated. For this reason, there was a case where the
efficiency of gasification was deteriorated.
[0007] One or more embodiments of the invention provide a
gasification system that improves the heat exchange efficiency in
the heat exchanger and thus gasifies a gasification feedstock
efficiently.
[0008] One or more embodiments of the present invention provide a
gasification system including a countercurrent type heat exchanger
configured to include a low-temperature side flow channel through
which a gasification feedstock flows, and a high-temperature side
flow channel to which treated water in a supercritical state is
introduced, the treated water raising a temperature of the
gasification feedstock by exchanging heat with the gasification
feedstock, a gasification reactor configured to gasify the
gasification feedstock, whose temperature has been raised by the
countercurrent type heat exchanger, by heating and pressurizing the
gasification feedstock to be in a supercritical state, the
gasification reactor being configured to discharge the gasification
feedstock as treated water in the supercritical state, and a
treated water flow channel configured to introduce, to the
countercurrent type heat exchanger, the treated water that has been
discharged from the gasification reactor, the gasification system
including: a feedstock introducing means (e.g., feedstock
introduction port) configured to introduce the gasification
feedstock to the low-temperature side flow channel; and an external
heating means (e.g., external heater) configured to extract, from
the middle of the low-temperature side flow channel, the
gasification feedstock that has been introduced by the feedstock
introducing means, heat the extracted gasification feedstock, and
return the heated gasification feedstock to a middle position on a
feedstock downstream side of a position in which the gasification
feedstock has been extracted.
[0009] According to one or more embodiments of the present
invention, the gasification feedstock that has been introduced to
the heat exchanger is extracted in the middle of the
low-temperature side flow channel, and the extracted gasification
feedstock is heated and returned to the feedstock downstream side
in the low-temperature side flow channel, thereby it is possible to
prevent the gasification feedstock from flowing through the point,
for example, in which the heat exchange efficiency deteriorates.
This can enhance the heat exchange efficiency in the heat
exchanger. Further, the gasification feedstock can be gasified
efficiently by heating the gasification feedstock by the external
heating means which is provided outside the heat exchanger.
[0010] In another aspect of one or more embodiments of the present
invention, a position in which the extraction is performed is
determined based on a value of specific heat at constant pressure
of the gasification feedstock, and the gasification feedstock is
extracted from the position that has been determined.
[0011] According to one or more embodiments of the present
invention, since the position in which the extraction is performed
is determined based on the specific heat at constant pressure, for
example, the gasification feedstock is extracted from a position in
which a value of the specific heat at constant pressure is low in
the heat exchanger, and thus the heat exchange efficiency can be
certainly enhanced.
[0012] In another aspect of one or more embodiments of the present
invention, the low-temperature side flow channel is configured to
include a low-temperature zone in which a temperature of the
gasification feedstock introduced by the gasification feedstock
introducing means is raised, and a high-temperature zone in which a
temperature of the gasification feedstock that has passed through
the low-temperature zone is raised again, and the external heating
means extracts the gasification feedstock from a high temperature
end of the low-temperature zone and returns the gasification
feedstock to a low temperature end of the high-temperature
zone.
[0013] As in one or more embodiments of the present invention, the
gasification feedstock is extracted from the high temperature end
of the low-temperature zone, and the extracted gasification
feedstock is returned to the low temperature end of the
high-temperature zone, so that the temperature of the gasification
feedstock can be certainly raised without allowing the gasification
feedstock to flow through a temperature zone in which the heat
exchange efficiency is low. This can perform gasification
efficiently.
[0014] It should be noted that, the specific heat at constant
pressure of the gasification feedstock at the position in which the
extraction is performed is, for example, 10 kJ/kgK or greater.
[0015] In another aspect of one or more embodiments of the present
invention, heating by the external heating means is performed in a
preheater that preheats the gasification feedstock whose
temperature has been raised by the countercurrent type heat
exchanger.
[0016] According to one or more embodiments of the present
invention, the heating of the gasification feedstock that has been
extracted from the countercurrent type heat exchanger is performed
by the preheater, and thus energy to be generated in the
gasification system can be used efficiently.
[0017] According to one or more embodiments of the present
invention, a gasification system can be provided in which the heat
exchange efficiency in the heat exchanger can be enhanced, and thus
the gasification feedstock is gasified efficiently.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1A is a diagram showing a schematic configuration of a
biomass gasification system 100 with supercritical water.
[0019] FIG. 1B a diagram illustrating an example of a double-pipe
configuration in a heat exchanger 30.
[0020] FIG. 2 is a diagram showing the heat exchanger 30 in a case
in which the length of a double-pipe from an introduction port 31
to a discharge port 32 of a gasification feedstock is set to
100.
[0021] FIG. 3 is a diagram showing an example of changes in
temperature ("tube temperature") of the gasification feedstock that
flows through a low-temperature side flow channel 36 and changes in
temperature ("jacket temperature") of treated water that flows
through a high-temperature side flow channel 37.
[0022] FIG. 4 is a diagram showing a relationship among
temperature, pressure, and specific heat at constant pressure.
[0023] FIG. 5 is an example of the heat exchanger 30 configured so
that a medium-temperature zone 72 does not exist.
[0024] FIG. 6 is a diagram illustrating appropriate positions for
an extracting position 33 and a return position 34 in the heat
exchanger 30.
[0025] FIG. 7 is a diagram showing a relationship among
temperature, pressure, and specific heat at constant pressure.
DETAILED DESCRIPTION
[0026] FIG. 1A is a diagram showing a schematic configuration of a
biomass gasification system 100 with supercritical water, which is
described as one or more embodiments of the present invention. As
illustrated in FIG. 1A, the gasification system 100 includes an
regulation tank 1, a crusher 2, a supply pump 3, a heat exchanger
30, a preheater 40, a gasification reactor 50, a cooler 51, a
pressure reducer 52, a gas-liquid separator 60, a gas tank 61 or
the like. The heat exchanger 30 and the gasification reactor are
connected by piping 55.
[0027] The regulation tank 1 is a tank for mixing biomass, water
and activated carbon, while regulating a mixing amount of water and
activated carbon in accordance with such as types, amount, and
water content of biomass. In the regulation tank 1, a gasification
feedstock (suspension) is prepared by mixing biomass, activated
carbon and water. Note that, the above-mentioned biomass is
water-containing biomass, for example, Shochu residue, egg-laying
hen droppings or the like. Further, other non-metal catalysts may
be mixed instead of the activated carbon, for example, zeolite may
be used, and a mixture thereof may also be used. Note that, powder
with an average particle size of 200 .mu.m or less may be used as a
non-metal catalyst, and may be a porous catalyst.
[0028] The crusher 2 is a device that crushes biomass in the
suspension, which has been prepared in the regulation tank 1, into
a uniform size in advance (an average particle size may be 500
.mu.m or less, even 300 .mu.m or less), and transfers the biomass
to the supply pump 3.
[0029] The supply pump 3 is a device that supplies the suspension
supplied from the crusher 2 to the exchanger 30. The supply pump 3
is, for example, a high pressure pump, Moineau pump and the
like.
[0030] The heat exchanger 30 is a countercurrent type heat
exchanger, and is a device that uses heat of discharged matter
(produced gas and ash which are discharged from the gasification
reactor 50, a non-metal catalyst and water (supercritical water) or
the like), which is discharged from the gasification reactor 50, to
raise the temperature of the gasification feedstock (suspension)
that is supplied from the supply pump 3. That is, this heat
exchanger 30 includes a low-temperature side flow channel 36 and a
high-temperature side flow channel 37, through which the
gasification feedstock that is supplied from the supply pump 3
flows. Treated water flows through the high-temperature side flow
channel 37, in which the treated water raises the temperature of
the gasification feedstock by exchanging heat with the gasification
feedstock that flows through the low-temperature side flow channel
36.
[0031] The above-mentioned discharged matter (treated water) is
introduced to the high-temperature side flow channel 37 through the
piping 55. Meanwhile, the temperature of the suspension that has
been introduced from the introduction port 31 is raised while
flowing through the low-temperature side flow channel 36, and the
suspension is discharged from the discharge port 32. Note that, the
internal pressure of the heat exchanger 30 is set to about 25
MPa.
[0032] The heat exchanger 30 is, for example, a double-pipe heat
exchanger. FIG. 1B is a diagram illustrating an example of a
double-pipe configuration in the heat exchanger 30. As illustrated
in FIG. 1B, the low-temperature side flow channel 36 is provided as
an inner pipe of the double-pipe, and the high-temperature side
flow channel 37 is provided as an outer pipe of the
double-pipe.
[0033] Referring back to FIG. 1A, the preheater 40 is a device that
heats the suspension to a predetermined temperature by burning such
as produced gas, fuel gas (for example LPG), and oxygen gas which
have been accumulated in the gas tank 61.
[0034] The gasification reactor 50 is, for example, a tubular
reactor, a fluidized-bed reactor or the like, and is a device for
gasifying biomass in a suspension with supercritical water. This
gasification uses the above-stated non-metal catalyst and is
performed at a temperature and under a pressure (for example,
600.degree. C. or greater, within 25 to 35 Mpa) which can enhance
reaction efficiency. By treating biomass with supercritical water
in this way, the biomass can be decomposed to produce gases such as
hydrogen gas, methane, ethane, and ethylene.
[0035] The cooler 51 is a device for cooling the discharged matter
that is discharged from the gasification reactor 50.
[0036] The pressure reducer 52 is a device for reducing the
pressure of the produced gas and the like of the discharged matter
that is discharged from the gasification reactor 50.
[0037] The gas-liquid separator 60 is a device that separates the
discharged matter, which is discharged from the gasification
reactor 50, into a gas component (produced gas) and a liquid
component (ash, activated carbon, and a mixed liquid containing
water).
[0038] The gas tank 61 is a container (for example, a pressure
resistant container) that accumulates a gas component (produced
gas) that is separated by the gas-liquid separator 60.
[0039] The heater 62 that is provided in the gasification reactor
50 is a device that burns, in the gas containing oxygen, a part of
the produced gas accumulated in the gas tank 61 or fuel gas (for
example, LPG and the like) to heat the gasification reactor 50, and
thus heats the suspension to a predetermined temperature. Further,
the heater 63 provided in the preheater 40 is a device that burns,
in the gas containing oxygen, a part of the produced gas
accumulated in the gas tank 61 or fuel gas (for example, LPG and
the like) to heat the preheater 40, and thus heats the suspension
to a predetermined temperature. The heaters 62 and 63 are existing
devices, such as a burner, that burn fuel gas for heating.
[0040] In such a gasification system 100, water that flows through
the high-temperature side flow channel 37 of the heat exchanger 30
is treated water in a supercritical state, which is discharged from
the gasification reactor 50, as described above, and the
temperature thereof is a high temperature such as at about
600.degree. C. Further, the internal pressure of the heat exchanger
30 is also a high pressure which is 25 MPa. In this
high-temperature and high-pressure condition, there is a case where
a temperature of the gasification feedstock is not sufficiently
raised in the heat exchanger 30.
[0041] FIG. 3 is a diagram showing an example of changes in
temperature ("tube temperature") of the gasification feedstock that
flows through the low-temperature side flow channel 36 and changes
in temperature ("jacket temperature") of the treated water that
flows through the high-temperature side flow channel 37 in using
the heat exchanger 30 (see FIG. 2) when the entire length of a
double-pipe from the introduction port 31 to the discharge port 32
is set to 100. As illustrated in FIG. 3, when treated water of
about 600.degree. C. is introduced to the heat exchanger 30, three
zones including a low-temperature zone 71, a medium-temperature
zone 72 and a high-temperature zone 73 are formed in the heat
exchanger 30 in the flowing order of the gasification feedstock (in
order closer to the introduction port 31). In other words, in the
low-temperature zone 71, the temperature of the gasification
feedstock introduced from the introduction port 31 is rapidly
raised from about 25.degree. C. to about 380.degree.. However, in
the medium-temperature zone 72, the temperature of the gasification
feedstock remains within a predetermined range and hardly rises
(remains at about 380.degree. C.). Then, in the high-temperature
zone 73, the temperature of the gasification feedstock is raised
again and reaches about 400.degree. C. rapidly.
[0042] Thus, although the temperature of the gasification feedstock
is rapidly raised in the low-temperature zone 71 and the
high-temperature zone 73, the temperature of the gasification
feedstock is hardly raised in the medium-temperature zone 72, and
thus the heat exchange treatment in the heat exchanger 30 is
inefficient as a whole. The length of the medium-temperature zone
72 exceeds 50 percent of the entire length of the double-pipe of
the heat exchanger 30 in some cases, this results in a reduction in
the heat exchange efficiency of the heat exchanger 30 especially in
those cases.
[0043] The reasons that the medium-temperature zone 72 exists are
as follows. FIG. 4 is a diagram showing a relationship among the
temperature of water, pressure and specific heat at constant
pressure. As illustrated in FIG. 4, when the internal pressure of
the heat exchanger 30 is 25 MPa, the specific heat at constant
pressure takes a specifically high value (reaches its peak) at
about 380.degree. C., and thus the temperature of the gasification
feedstock having such a temperature is not easily raised. Further,
also in the treated water that exchanges heat with the gasification
feedstock, the specific heat at constant pressure reaches its peak
at about 380.degree. C. (more precisely, reaches its peak at
somewhat lower temperature than the case of the gasification
feedstock due to a pressure loss in the double-pipe) as in the case
of the gasification feedstock.
[0044] Then, the present inventors conceive that, if the heat
exchanger 30 is configured so that a zone (a zone in which the
temperature of the gasification feedstock is about 380.degree. C.
in the example described above) in which the temperature of the
gasification feedstock is hardly raised does not exist in the heat
exchanger 30, in other words, so that the medium-temperature zone
72 does not exist, the heat exchange efficiency in the heat
exchanger 30 can be enhanced.
[0045] FIG. 5 illustrates one example of the heat exchanger 30
having such a configuration. As illustrated in FIG. 5, an external
heating means 35 for heating the gasification feedstock is provided
outside the heat exchanger 30. In other words, a flow channel is
changed in a manner in which, the gasification feedstock is
extracted from a predetermined position 33 (hereinafter, referred
to as an extracting position 33) of the low-temperature side flow
channel 36 as shown by a reference number 35a, the extracted
gasification feedstock is heated by heat of the preheater 40 as
shown by a reference number 35b, and the heated gasification
feedstock is returned to a predetermined position 34 (hereinafter,
referred to as a return position 34) of the low-temperature flow
channel 36, which is arranged on a feedstock downstream side of the
extracting position 33 as shown by a reference number 35c. This
change of the flow channel is performed, for example, by connecting
between the extracting position 33 and the preheater 40 with piping
so as to allow the gasification feedstock to flow therethrough, and
by connecting between the preheater 40 and the return position 34
with piping so as to allow the gasification feedstock to flow
therethrough.
[0046] Specifically, the extracting position 33 and the return
position 34 described above are positions as follows. That is, as
illustrated in FIG. 5, the extracting position 33 is a position in
which a temperature Tc of the gasification feedstock becomes
370.degree. C., and a temperature Td of the treated water becomes
375.degree. C. (that is, a high temperature end of the
low-temperature zone 71, and a boundary part with the
medium-temperature zone 72). Further, the return position 34 is a
position in which a temperature Te of the gasification feedstock
becomes 385.degree. C., and a temperature Tf of the treated water
becomes 390.degree. C. (that is, a low temperature end of the
high-temperature zone 73, and a boundary part with the
medium-temperature zone 72).
[0047] Note that, in response to such a change of the flow channel
of the low-temperature side flow channel 36, the flow channel of
the high-temperature side flow channel 37 is also changed. That is,
as illustrated in FIG. 5, the flow channel is configured so that
the extracting position 33 and the return position 34 are connected
with bypass piping 38, and the treated water directly flows from
the return position 34 to the extracting position 33. Further, a
surplus portion 39 of the piping is removed due to the
above-mentioned change of the flow channel.
[0048] As described above, the extracting position 33 is provided
at a boundary part between a low-temperature area 71 and a
medium-temperature area 72, and the return position 34 is provided
at a boundary part between the medium-temperature area 72 and a
high-temperature area 73, so that the heat exchange efficiency in
the heat exchanger 30 can be enhanced and the temperature of the
gasification feedstock can be certainly raised.
[0049] Further, in this way, in the heat exchanger 30, an area does
not exist in which the temperature of the gasification feedstock
becomes about 380.degree. C. that is a temperature at which a heat
exchange rate of fluid reduces. In such a temperature, tar is
produced in the double-pipe, and the inner pipe (low-temperature
side flow channel 36) and the outer pipe (high-temperature side
flow channel 37) are easily clogged. Thus, in order to avoid this,
by providing the extracting position 33 and the return position 34
as stated above, production of tar can be suppressed and the piping
can be prevented from being clogged, so that reliability of the
gasification system 100 can be improved.
[0050] Further, since expensive and thick-walled piping is
generally used for the heat exchanger 30 to resist a
high-temperature and high-pressure condition, incidental expenses
associated with maintenance of piping or the like can be suppressed
by performing such a change of the flow channel that the
medium-temperature zone 72 is omitted as stated above.
[0051] Further, the heating of the gasification feedstock that has
been extracted from the heat exchanger 30 is performed by the
preheater 40, and thus energy efficiency in the gasification system
100 can be enhanced. Further, new introduction of a heating
facility is not necessary, and it is possible to prevent a cost
from increasing.
[0052] In the example described above, the position in which the
temperature of the gasification feedstock becomes about 370.degree.
C. is referred to as the extracting position 33, and the position
in which the temperature of the gasification feedstock becomes
about 385.degree. C. is referred to as the return position 34.
However, the extracting position 33 and the return position 34 are
not limited to those positions. That is, the extracting position 33
may be a boundary part between the low-temperature zone 71 and the
medium-temperature zone 72. Further, the return position 34 may be
a boundary part between the medium-temperature zone 72 and the
high-temperature zone 73.
[0053] FIG. 6 is a diagram illustrating appropriate positions for
the extracting position 33 and the return position 34 in the heat
exchanger 30. As illustrated in FIG. 6, the extracting position 33
may be arranged somewhere at a position in which the specific heat
at constant pressure is relatively high (for example, in a range
indicated by a reference number 33a to a reference number 33b) near
the point in which the specific heat at constant pressure of the
gasification feedstock reaches a peak value at the closer side to
the introduction port 31 (the point in which the temperature of the
gasification feedstock becomes about 380.degree. C.). For example,
the extracting position 33 is such a position that the specific
heat at constant pressure becomes 10 kJ/kgK or greater.
[0054] On the other hand, the return position 34 may be arranged
somewhere at a position in which the specific heat at constant
pressure is relatively high (for example, in a range indicated by a
reference number 34a to a reference number 34b) near the point in
which the specific heat at constant pressure of the gasification
feedstock reaches a peak value at the closer side to the discharge
port 32 (the point in which the temperature of the gasification
feedstock becomes about 380.degree. C.). For example, the return
position is such a position that the specific heat at constant
pressure becomes 10 kJ/kgK.
[0055] Note that, in the above description, the internal pressure
of the heat exchanger 30 is assumed to be 25 MPa. However, the
internal pressure of the heat exchanger 30 may vary. If the
internal pressure varies, a peak temperature of the specific heat
at constant pressure also varies (see FIG. 4), and thus, when the
internal pressure of the heat exchanger 30 varies, the extracting
position 33 is regulated in response thereto.
[0056] Next, how to determine the extracting position 33 in a case
in which the internal pressure of the heat exchanger 30 varies will
be described.
[0057] FIG. 7 is a diagram showing a relationship among temperature
of water, pressure and specific heat at constant pressure, which is
used for determining the extracting position 33. As illustrated in
FIG. 7, a curved surface 74 indicates an aggregation of plots of
temperature and pressure at which the specific heat at constant
pressure exceeds a predetermined value. It is possible to determine
an appropriate extracting position 33 by reading out, from the
curved surface 74, a temperature corresponding to the current
pressure of the heat exchanger 30.
[0058] As stated above, even when the internal pressure of the heat
exchanger 30 varies, it is possible to enhance the heat exchange
efficiency in the heat exchanger 30 by determining the extracting
position 33 and the return position 34 on the basis of values of
the specific heat at constant pressure.
[0059] As described above, according to the gasification system 100
of one or more embodiments of the invention, the gasification
feedstock introduced to the heat exchanger 30 is extracted in the
middle of the low-temperature side flow channel 36, the extracted
gasification feedstock is heated and returned in the middle of the
low-temperature side flow channel 36, and thus, for example, it
becomes possible to prevent the gasification feedstock from flowing
through the point in which the heat exchange efficiency
deteriorates. This can enhance the heat exchange efficiency in the
heat exchanger 30. Further, the gasification feedstock is heated in
the external heating means (preheater 40) which is provided outside
the heat exchanger 30, and thus the gasification feedstock can be
efficiently gasified. Moreover, new introduction of a heating
facility is not necessary, and it is possible to prevent a cost
from increasing.
[0060] Further, since the position where the extraction is
performed (extracting position 33) is determined based on the
specific heat at constant pressure, the heat exchange efficiency
can be certainly enhanced by, for example, extracting the
gasification feedstock from a position in which the specific heat
at constant pressure is low in the heat exchanger 30.
[0061] Further, since the gasification feedstock is extracted from
the boundary part between the low-temperature zone 71 and the
medium-temperature zone 72, and the extracted gasification
feedstock is returned to the boundary part between the
medium-temperature zone 72 and the high-temperature zone 73, the
temperature of the gasification feedstock can be certainly raised
without allowing the gasification feedstock to flow through the
medium-temperature zone 72 in which the heat exchange efficiency is
low. This can perform gasification efficiently.
[0062] The above description of one or more embodiments of the
invention is to facilitate understanding of one or more embodiments
of the present invention, and does not limit the present invention.
The present invention may be modified and improved without
departing from the scope thereof, and the present invention
includes equivalents thereof.
[0063] For example, the double-pipe heat exchanger has been adopted
as the heat exchanger 30 in one or more embodiments of the
invention. However, other types of heat exchangers may be adopted,
as long as the heat exchanger is a countercurrent system.
[0064] Further, in one or more embodiments of the invention, a
method of using the preheater 40 that is an existing facility is
described as a means of heating the gasification feedstock that has
been extracted from the extracting position 33. However, the
gasification feedstock may be heated by newly providing an external
heating means (a heater or the like).
[0065] Although the disclosure has been described with respect to
only a limited number of embodiments, those skilled in the art,
having benefit of this disclosure, will appreciate that various
other embodiments may be devised without departing from the scope
of the present invention. Accordingly, the scope of the invention
should be limited only by the attached claims
REFERENCE SIGNS LIST
[0066] 1 regulation tank, 2 crusher, 3 supply pump, 30 heat
exchanger, 31 introduction port, 32 discharge port, 33 extracting
position, 34 return position, 35 external heating means, 36
low-temperature side flow channel, 37 high-temperature side flow
channel, 38 bypass piping, 39 surplus portion, 40 preheater, 50
gasification reactor, 51 cooler, 52 pressure reducer, 55 piping, 60
gas-liquid separator, 61 gas tank, 62 heater, 63 heater, 71
low-temperature zone, 72 medium-temperature zone, 73
high-temperature zone, 74 a curved surface, 100 gasification
system
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