JP5242206B2 - Method for separating and recovering carbon dioxide from blast furnace gas - Google Patents

Description

  The present invention relates to a method for separating and recovering carbon dioxide from blast furnace gas, and to a method for efficiently separating and recovering carbon dioxide from blast furnace gas without supplying heat from the outside.

In order to prevent global warming, reduction of carbon dioxide emissions has become an important issue, and various proposals have been made regarding methods for separating and recovering carbon dioxide.
For example, Patent Document 1 discloses a method of separating and recovering carbon dioxide from a by-product gas generated at an ironworks by a chemical absorption method, and after absorbing carbon dioxide from the gas with a chemical absorption liquid, the chemical absorption liquid By utilizing or utilizing low-grade exhaust heat generated in steelworks for the process of heating and separating carbon dioxide, carbon dioxide emitted from large-scale carbon dioxide sources can be efficiently and inexpensively provided with compact equipment. A method for separating and collecting carbon dioxide to be separated and recovered is described.

This patent document 1 describes a method for separating and recovering carbon dioxide from a by-product gas (BFG, COG, LDG, etc.) generated at an ironworks by a chemical absorption method. For example, waste heat from a sintered product cooler (about 350 ° C.), main exhaust gas (about 280 ° C.), exhaust gas from a hot stove ( It is disclosed that low-grade exhaust heat such as about 230 ° C.), sintered main exhaust gas (about 180 ° C.), waste water used for granulating blast furnace slag (about 90 ° C.), or the like is used or utilized.
Moreover, since the blast furnace gas discharged from the blast furnace has a pressure of 0.2 to 0.3 MPa after the dust is removed by the dust collector, power generation is performed using TRT (Top pressure Recovery Turbine). It is used for. After that, it is used as a fuel gas for heating and power generation in the iron making process.
In recent years, in order to improve power generation efficiency, a method of generating power by burning blast furnace gas with a gas turbine power generator has been adopted. Such a method is disclosed in Patent Document 2, for example.

  The outline of the prior art will be described with reference to FIG. FIG. 5 is a system diagram of a soot gas turbine power generator using blast furnace gas as fuel. Blast furnace gas A (BFG) is generated from a blast furnace (not shown) and cleaned by various dust collectors including a dust catcher 1, a first venturi scrubber 2, a second venturi scrubber 3, and a dry dust collector 4. Thereafter, the pressure is reduced to near atmospheric pressure by the blast furnace gas pressure reducing means comprising the TRT 5 or the pressure reducing valve (4) 6 and the sun lens 7, and then stored in the gas holder 8. When using the BFG as a fuel for a gas turbine power generator, it is mixed with coke oven gas (COG) (not shown) to increase the amount of heat required for gas turbine combustion and compressed by the fuel gas compressor 9-1 Is done. The compressed fuel gas is mixed with the compressed air exiting the air compressor 9-5 and combusted in the combustor 9-2 to drive the gas turbine 9-3 to become exhaust gas, and further to the steam boiler Steam is generated at 9-4 and becomes a power source for the steam turbine 9-7. Reference numeral 9-6 represents a generator, and reference numeral 9-8 represents a condenser.

JP 2004-292298 A JP-A-9-79046

However, in Patent Document 1, carbon dioxide is absorbed by the chemical absorbing solution disclosed in the above, and then the low-grade exhaust heat generated at the steel works is used or utilized for the process of heating the chemical absorbing solution and separating the carbon dioxide. The technology has the following problems and cannot be used as a practical technology.
Since the amount of blast furnace gas discharged from the blast furnace is extremely large, the amount of treatment becomes large. Therefore, in the process described above, the method of using the low-grade exhaust heat generated at the steelworks to heat and regenerate the absorbing solution that has absorbed a large amount of carbon dioxide has a very short heating energy. Therefore, in order to process the large amount of blast furnace gas, it is necessary to arrange a new heating means for heating and regenerating the absorbing liquid, and it is difficult to realize it as a practical technique.
On the other hand, in Patent Document 2, there is no disclosure about absorption / separation of carbon dioxide in gas. Therefore, the carbon dioxide contained in the exhaust gas from the gas turbine after blast furnace gas combustion cannot be processed.

    An object of the present invention is to solve the above-described problems of the prior art and improve the power generation efficiency, in a method of generating power by burning a cleaned blast furnace gas in a gas turbine power generator, It can be separated and recovered without arranging new heating means to heat and regenerate the absorbing liquid that has absorbed a large amount of carbon dioxide contained in the exhaust gas from the gas turbine after the middle and / or blast furnace gas combustion The object is to provide a method for separating and recovering carbon dioxide from blast furnace gas.

  In the method for separating and recovering carbon dioxide from blast furnace gas according to the present invention, the blast furnace gas taken out from the blast furnace is introduced into an absorption tower, and the carbon dioxide in the blast furnace gas is absorbed by the absorption liquid in the absorption tower, and the carbon dioxide. A part of the blast furnace gas from which carbon has been removed is burned in a steel making process and used as a heat source, and another part of the blast furnace gas from which the carbon dioxide has been removed is introduced into a gas turbine power generator and burned. The absorption liquid that is used as a fuel for power generation and has absorbed the carbon dioxide in the absorption tower is heated by the heat of the exhaust gas of the gas turbine, and the heated absorption liquid is introduced into the regeneration tower, The carbon dioxide is removed from the absorption liquid, and the absorption liquid from which the carbon dioxide has been removed is circulated to the absorption tower.

  In the present invention, the blast furnace gas from the blast furnace is used for power generation as a fuel for a gas turbine power generation device while carbon dioxide is removed in an absorption tower and is used as a heating fuel in an iron making process. Further, the exhaust gas from the gas turbine is used to regenerate the absorption liquid used for removing carbon dioxide in the previous absorption tower. Therefore, carbon dioxide can be separated and recovered efficiently. Further, since carbon dioxide, which is an incombustible component in the blast furnace gas, is removed, the amount of heat as fuel gas is increased, and the amount of addition of a fuel increasing material such as COG can be reduced.

In the method for separating and recovering carbon dioxide from blast furnace gas according to the present invention, it is preferable that the absorption tower is installed in front of the blast furnace gas decompression means, and the blast furnace gas is introduced into the absorption tower in a high pressure state.
In such an invention, in the absorption tower, the blast furnace gas can be set to a high pressure before depressurization, and the absorption performance of carbon dioxide into the absorption liquid can be maintained high.

In the method for separating and recovering carbon dioxide from blast furnace gas according to the present invention, the exhaust gas of the gas turbine power generator is introduced into a sub-absorption tower, and the absorption liquid absorbs carbon dioxide in the exhaust gas in the sub-absorption tower. desirable.
In the present invention, carbon dioxide contained in the blast furnace gas from the blast furnace is absorbed by the absorption tower described above, and carbon dioxide generated by the subsequent combustion of the blast furnace gas in the gas turbine power generator is sub-absorbed. It can be absorbed by the tower and can be efficiently operated by circulating the absorption liquid while increasing the amount of carbon dioxide separated and recovered.

In the method for separating and recovering carbon dioxide from blast furnace gas according to the present invention, when the amount of heat necessary for heating the absorption liquid is significantly smaller than the amount of heat of the exhaust gas of the gas turbine, the gas turbine power generator A steam boiler that generates high-pressure steam using a part of the heat of the exhaust gas from the turbine, a steam turbine that uses high-pressure steam from the steam boiler as power for the gas turbine power generation device, and a used steam turbine It is desirable to use a device having a condenser for condensing steam, and use the heat of the gas turbine exhaust gas and the condensate heat in the condenser for heating the absorption liquid.
In the present invention, since the condensate heat that has been discarded by the gas turbine power generation device is used for heating the absorption liquid, the efficiency of use of heat generated by the combustion of the blast furnace gas in the gas turbine power generation device is improved. To do.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1A shows a first embodiment of the present invention.
In FIG. 1A, 5 is a TRT (furnace top pressure recovery turbine), 6 is a pressure reducing valve, 7 is a silencer, and the pressure reducing means for the blast furnace gas is configured as described above.
8 is a gas holder, 9-1 is a fuel gas compressor, 9-2 is a combustor, 9-3 is a gas turbine, 9-4A ... a heat exchanger for heating carbon dioxide absorption liquid, 9-5 is an air compressor, 9 -6 shows each generator.

9 includes a fuel gas compressor 9-1, a combustor 9-2, a gas turbine 9-3, a heat exchanger 9-4A for heating carbon dioxide absorption liquid, an air compressor 9-5, and power generation. Machine 9-6. Reference numeral 10 denotes an absorption tower, and 12 denotes a regeneration tower.
In the figure, the arrow B is the high-pressure clean blast furnace gas cleaned by the various dust collectors (not shown) described in the section of the prior art, part of which is branched to the line C and the other part is It is discharged to an arrow G via lines E and F. On the other hand, the flow indicated by arrows L and M indicates the circulation flow of the carbon dioxide absorption liquid. Arrow K is the separated carbon dioxide.
In the following embodiments, the same symbols are used for the same elements to avoid duplication of explanation.

As the carbon dioxide separation and absorption method applied to the present invention, for example, a chemical absorption method is used, and a chemical absorption solution such as amines is used.
The high-pressure clean blast furnace gas B taken out from the blast furnace and purified is introduced into the absorption tower 10 installed in the previous stage of the pressure reducing means for the blast furnace gas. In the absorption tower 10, the blast furnace gas is brought into contact with a chemical absorption liquid that is a carbon dioxide absorption medium at around 50 ° C., and carbon dioxide in the blast furnace gas is absorbed by the chemical absorption liquid.
Thereafter, a part of the blast furnace gas from which the carbon dioxide has been removed passes through the gas holder 8 and is conveyed to, for example, a coke oven, a heating furnace (not shown) and burned in various iron making processes to be used as a heat source. .

On the other hand, the other part of the blast furnace gas from which the carbon dioxide has been removed is compressed by the fuel gas compressor 9-1. The compressed fuel gas is mixed and burned in the combustor 9-2 with the compressed air exiting the air compressor 9-5 to drive the gas turbine 9-3, and the exhaust gas is heated by the carbon dioxide absorption liquid. It is discharged | emitted from the chimney in air | atmosphere through the heat exchanger 9-4A.
At this time, the absorption liquid that has absorbed the carbon dioxide in the absorption tower 10 is heated to about 120 ° C. in the heat exchanger 9-4A for heating the carbon dioxide absorption liquid by the heat of the exhaust gas of the gas turbine 9-3. Thereafter, carbon dioxide is separated and recovered from the absorption liquid in the regeneration tower 12, and the regenerated absorption liquid is returned to the absorption tower 10 through a return pipe, so that the absorption liquid circulates between the absorption tower 10 and the regeneration tower 12. Can be recycled.

As described above, the exhaust gas from the gas turbine power generation device 9 is used to regenerate the absorption liquid whose heat was used to remove carbon dioxide in the previous absorption tower. Accordingly, carbon dioxide can be separated and recovered efficiently and a large amount of blast furnace gas can be processed without providing new heating means.
Since the total heat quantity of the exhaust gas from the gas turbine 9-3 is used for heating the carbon dioxide absorption liquid in the heat exchanger 9-4A for heating the carbon oxide absorption liquid, the steam shown in FIG. It is not necessary to install the turbine 9-7, and energy can be effectively used with a simple equipment configuration. In addition, because carbon dioxide, which is an incombustible component in blast furnace gas, is removed, the amount of heat as fuel gas increases, and the amount of additional fuel-enhancing materials such as COG can be reduced

Further, as described above, the carbon dioxide separated and recovered is, for example, compressed and injected into the ground in a supercritical state, so that carbon dioxide discharged into the atmosphere can be greatly reduced.
Further, since the position of the absorption tower 10 is arranged after the various dust collectors for the blast furnace gas, the blast furnace gas is purified and the absorbing solution does not deteriorate.
Furthermore, the absorption tower 10 is installed in the front stage of the blast furnace gas decompression means, and the blast furnace gas is introduced into the absorption tower 10 in a high pressure state. Therefore, in the present invention, in the absorption tower, the blast furnace gas can be set to a high pressure before depressurization, and the absorption performance of carbon dioxide into the absorption liquid can be maintained high.

[Second Embodiment]
FIG. 2A shows a second embodiment of the present invention.
In FIG. 2A, the structural difference of the present embodiment from the first embodiment is that the absorption tower 10 is installed in the subsequent stage of the blast furnace gas pressure reducing means (furnace top pressure recovery turbine 5 and pressure reducing valve 6). It is that you are. The other configuration is the same as that shown in FIG.
Such a configuration of FIG. 2A also provides the same effect as in FIG. 1A. However, since the absorption tower 10 is the latter stage of the blast furnace gas decompression means, the absorption performance does not reach that of the first embodiment.

[Third Embodiment]
FIG. 1B shows a third embodiment of the present invention.
In FIG. 1B, in addition to the configuration described in FIG. 1A, the configuration is that a sub-absorption tower 11 is newly provided after the heat exchanger 9-4A for heating the carbon dioxide absorption liquid.
The other configuration is the same as that shown in FIG.
The exhaust gas from the gas turbine power generation device 9 comes into contact with the absorption liquid in the sub-absorption tower 11, and after carbon dioxide is removed from the exhaust gas, it is discharged out of the system.
On the other hand, the absorption liquid that has absorbed carbon dioxide is merged with the absorption liquid that has absorbed carbon dioxide in the absorption tower 10, and then the heat of the exhaust gas of the gas turbine is used to heat the carbon dioxide absorption liquid heat exchanger 9-. 4A is heated to around 120 ° C., and carbon dioxide is separated and recovered from the chemical absorption liquid in the regeneration tower 12.

[Fourth Embodiment]
FIG. 6 shows a fourth embodiment of the present invention.
In FIG. 6, in addition to the configuration described in FIG. 1B, the exhaust gas N of the iron making process is introduced into the carbon dioxide absorbent heating heat exchanger 9-4 </ b> A, and the exhaust gas of the gas turbine power generation device 9 is configured. It is the point that was merged with. Since the other points are the same as those in FIG. 1B, a duplicate description is omitted.
The exhaust gas L of the iron making process is brought into contact with the absorbing liquid in the sub-absorption tower 11 together with the exhaust gas of the gas turbine power generation device 9, and after carbon dioxide is removed from the exhaust gas, it is discharged into the body. Moreover, by mixing the exhaust gas from the gas turbine and the exhaust gas from the iron making process, the gas temperature in the heat exchanger for heating the carbon dioxide absorption liquid decreases, and the carbon dioxide absorption liquid is overheated and deteriorated. Can be prevented.

[Fifth Embodiment]
FIG. 2B shows a fifth embodiment of the present invention.
In FIG. 2B, the structure has installed the absorption tower 10 in the back | latter stage of the pressure reduction means of the said blast furnace gas. The other configuration is the same as that shown in FIG.
Such a configuration of FIG. 2B also provides the same effect as in FIG. 1B. However, since the absorption tower 10 is the latter stage of the blast furnace gas decompression means, the absorption performance does not reach that of the first embodiment.

[Sixth Embodiment]
FIG. 3A shows a sixth embodiment of the present invention.
In FIG. 3A, 9-4 steam boiler, 9-7 is a steam turbine, 9-8 shows the condenser which condenses the used steam from the said steam turbine 9-7. Two heat exchange pipes are provided in the steam boiler 13. The heat of the exhaust gas from the gas turbine 9-3 generates one of the high-pressure steam I, drives the steam turbine 9-7 to generate electric power, and the other is the absorption tower 10, which is the CO2 in the blast furnace gas. It is a heat exchange conduit for heating the carbon dioxide absorbing liquid L that has adsorbed carbon dioxide in order to separate carbon dioxide from the absorbing liquid L that has adsorbed carbon.

The method of applying the method for separating and recovering carbon dioxide from blast furnace gas having such a configuration is preferably performed when the amount of heat necessary for heating the absorption liquid is significantly less than the amount of heat of the exhaust gas of the gas turbine 9-7. .
That is, as the gas turbine power generation device 9, a steam boiler 9-4 that generates high-pressure steam using a part of the heat of the exhaust gas of the gas turbine 9-3, and the high-pressure steam from the steam boiler are used as the gas turbine. For heating the absorption liquid, a device having a steam turbine 9-7 used as power for the power generation device 9 and a condenser 9-8 for condensing used steam from the steam turbine 9-7 is used. It is desirable to use a part of the heat of the exhaust gas of the gas turbine 9-3 and the condensate heat in the condenser 9-8.
In the present invention, since the condensate heat previously discarded in the condenser 9-8 constituting the gas turbine power generation device 9 is used for heating the absorption liquid, the gas turbine power generation device 9 uses the blast furnace gas. The utilization efficiency of the heat generated by the combustion is improved.

[Seventh Embodiment]
FIG. 3B shows a seventh embodiment of the present invention.
In FIG. 3B, in addition to the configuration described in FIG. 3A, the sub-absorption tower 11 is provided at the rear stage of the heat exchanger 9-4A for heating the carbon dioxide absorption liquid.
The other configuration is the same as that shown in FIG.
The exhaust gas from the gas turbine power generation device 9 comes into contact with the absorption liquid in the sub-absorption tower 11, and after carbon dioxide is removed from the exhaust gas, it is discharged out of the system.
On the other hand, the absorption liquid that has absorbed carbon dioxide is merged with the absorption liquid that has absorbed carbon dioxide in the absorption tower 10, and then heat exchange for heating the carbon dioxide absorption liquid with the heat of the exhaust gas of the gas turbine 9-3. It is heated to around 120 ° C. in the vessel 9-4A, and carbon dioxide is separated and recovered from the absorbent in the regeneration tower 12.

[Eighth Embodiment]
FIG. 4A shows an eighth embodiment of the present invention.
In FIG. 4A, the structure is the structure demonstrated in the said FIG. 3A, and the absorption tower 10 is arrange | positioned in the back | latter stage of the pressure reduction means of blast furnace gas.
The other configuration is the same as that shown in FIG.

[Ninth Embodiment]
FIG. 4B shows a ninth embodiment of the present invention.
In FIG. 4B, the configuration is that, in addition to the configuration described in FIG. 4A, a secondary absorption tower 11 is newly provided after the heat exchanger 9-4A for heating the carbon dioxide absorption liquid.
The other configuration is the same as that shown in FIG.

[Modification]
In addition, this invention is not limited to the structure of the said embodiment, The deformation | transformation etc. in the range which intends to achieve the objective of this invention are included in this invention.
1B, FIG. 2B, FIG. 3B, and FIG. 4B, after the merging of the absorption liquid that adsorbs carbon dioxide in the sub-absorption tower 11 and the absorption liquid that adsorbs carbon dioxide in the absorption tower 10 once However, the present invention is not limited to this, and the present invention is not limited to this, and from each of the absorption towers individually, the heat exchanger 9 for heating the carbon dioxide absorption liquid. Even if it is transported to -4A, the same effect is produced.

  The method for separating and recovering carbon dioxide from blast furnace gas according to the present invention includes a step of generating power by burning purified blast furnace gas in a gas turbine power generator, exhaust gas from blast furnace gas and / or gas turbine after blast furnace gas combustion. It can be used as a process for heating and regenerating an absorbing solution that has absorbed a large amount of carbon dioxide contained therein.

1 is a block diagram showing a first embodiment of the present invention. It is a block diagram which shows 3rd Embodiment of this invention. It is a block diagram which shows 2nd Embodiment of this invention. It is a block diagram which shows 5th Embodiment of this invention. It is a block diagram which shows 6th Embodiment of this invention. It is a block diagram which shows 7th Embodiment of this invention. It is a block diagram which shows the said 8th Embodiment. It is a block diagram which shows 9th Embodiment of this invention. It is a block diagram which shows a prior art example. It is a block diagram which shows 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Dust catcher 2 ... 1st venturi scrubber 3 ... 2nd venturi scrubber 4 ... Dry type dust collector 5 ... TRT (furnace top pressure recovery turbine)
DESCRIPTION OF SYMBOLS 6 ... Pressure reducing valve 7 ... Silencer 8 ... Gas holder 9 ... Gas turbine power generation device 9-1 ... Fuel gas compressor 9-2 ... Combustor 9-3 ... Gas turbine 9-4 ... Steam boiler 9-4A ... Carbon dioxide absorption liquid Heat exchanger for heating 9-5 ... Air compressor 9-6 ... Generator 9-7 ... Steam turbine 9-8 ... Condenser 10 ... Absorption tower 11 ... Sub-absorption tower 12 ... Regeneration tower A ... Blast furnace gas B ... High pressure clean blast furnace gas C ... Fuel gas for heating in iron making process D ... Coke oven gas E ... Fuel gas for gas turbine generator F ... Air G ... Exhaust gas H ... Cooling water I ... Steam J ... Off-gas K ... Carbon dioxide L ... Dioxide Carbon dioxide absorbing liquid that adsorbs carbon M ... Carbon dioxide absorbing liquid before carbon dioxide is adsorbed N ... Exhaust gas from iron making process

Claims (4)

  A blast furnace gas taken out from a blast furnace is introduced into an absorption tower, carbon dioxide in the blast furnace gas is absorbed into the absorption liquid in the absorption tower, and a part of the blast furnace gas from which the carbon dioxide has been removed is an iron manufacturing process. The other part of the blast furnace gas from which the carbon dioxide has been removed is used as a fuel for generating power by burning it in a gas turbine power generator, The absorption liquid that has absorbed carbon is heated by the heat of the exhaust gas of the gas turbine, the heated absorption liquid is introduced into a regeneration tower, the carbon dioxide is removed from the absorption liquid in the regeneration tower, and the carbon dioxide A method for separating and recovering carbon dioxide from blast furnace gas, wherein the absorption liquid from which gas is removed is circulated to the absorption tower. The method for separating and recovering carbon dioxide from blast furnace gas according to claim 1,
A method for separating and recovering carbon dioxide from blast furnace gas, wherein the absorption tower is installed in front of the blast furnace gas decompression means, and the blast furnace gas is introduced into the absorption tower in a high pressure state. In the method for separating and recovering carbon dioxide from blast furnace gas according to claim 1 or 2,
A method for separating and recovering carbon dioxide from blast furnace gas, wherein exhaust gas from the gas turbine power generator is introduced into a sub-absorption tower, and carbon dioxide in the exhaust gas is absorbed into the absorption liquid in the sub-absorption tower. In the method for separating and recovering carbon dioxide from blast furnace gas according to any one of claims 1 to 3,
As the gas turbine power generator, a steam boiler that generates high-pressure steam using the heat of exhaust gas from the gas turbine, a steam turbine that uses high-pressure steam from the steam boiler as power for the gas turbine power generator, and the steam Using a device having a condenser for condensing used steam from a turbine, and utilizing a part of the heat of the exhaust gas of the gas turbine and the heat of the condenser for heating the absorption liquid, To separate and recover carbon dioxide from blast furnace gas.

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