JP6153162B2 - CO2 recovery type closed cycle gasification power generation system - Google Patents

Description

The present invention relates to a CO ₂ recovery type closed cycle gasification power generation system, and is particularly useful when applied to a closed cycle combined power generation system in which a turbine is driven using gasification gas generated in a gasification facility as fuel.

When fossil fuel is used as the fuel for the gas turbine, CO ₂ that causes global warming is generated. Therefore, CO ₂ recovering closed cycle coal gasification power generation system for a high-efficiency power generation while separating and recovering the CO ₂ has been proposed (see Non-Patent Document 1). FIG. 7 is a block diagram showing a proposed CO ₂ recovery type closed cycle coal gasification power generation system according to the prior art. As shown in the figure, the CO ₂ recovery type closed cycle coal gasification power generation system VII (hereinafter also referred to as the system VII) is supplied with coal as fuel and oxygen generated in the oxygen production facility 2. A coal gasification facility 1 that generates gas, a combustor 5 that generates combustion gas using coal gas generated by the coal gasification facility 1 and purified by the metal filter 3 and the dry desulfurizer 4, and the combustion gas And a gas turbine 6 that drives the generator 7. Further, the compressor 8 of the system VII compresses a part of the exhaust gas worked in the gas turbine 6 and mixes the compressed exhaust gas with a part of the oxygen generated in the oxygen production facility 2 and heats the exhaust gas. The regenerative heat exchanger 9 utilizing the heat is returned to the combustor 5 by heating. Thus, in the combustor 5, coal gas, which is fuel, is combusted by a mixed gas of a part of oxygen generated in the oxygen production facility 2 and the exhaust gas compressed by the compressor 8. This improves the efficiency of the system VII.

Further, in the system VII, the halogen in the exhaust gas of the gas turbine 6 is removed by the water washing tower of the brackish water separator 10, and after the exhaust gas is further compressed by the compressor 11, mercury is removed by the mercury removing unit 12. The water is separated by the brackish water separator 13 and supplied to the compressor 14. In the compressor 14, a part of the compressed exhaust gas is supplied to the CO ₂ recovery device 16 through the compressor 15, and the remaining part is returned to the coal gasification facility 1. Thereby, the gasification efficiency of coal gas in the coal gasification facility 1 is improved, and more CO is generated.

  In the system VII, the steam turbine 17 is driven using the heat of the exhaust gas worked in the gas turbine 6, and the steam turbine 17 drives the generator 18. That is, the system VII is constructed as a combined power generation system. Therefore, on the downstream side of the gas turbine 6, an exhaust heat recovery boiler 19 and a heat exchanger 20 that recover the heat of the exhaust gas of the gas turbine 6 are arranged. Has been. Thus, the steam that has worked in the steam turbine 17 is condensed in the condenser 21 to become water, and is supplied to the exhaust heat recovery boiler 19 through the heat exchanger 20 by the condensate pump, and becomes steam to become the steam turbine 17. To be supplied.

October 2007, Report of Central Research Institute of Electric Power Industry, Research Report: M07003

The CO ₂ recovery type closed cycle coal gasification power generation system VII as described above is intended to reduce the required energy and power associated with CO ₂ recovery and improve the power generation efficiency. 5, when the ratio of coal gasification gas and oxygen is burned in the vicinity of an equivalent amount, CO and O ₂ tend to remain in the exhaust gas discharged from the gas turbine 6, and if these remain, thermal efficiency decreases and CO ₂ recovery occurs. There is a risk that the rate will decrease. If the CO is not completely converted to CO ₂ can not obtain a heat due to not converted CO, also the residual O ₂ is increased, useless power for circulating the O ₂ remaining This is because it increases and the purity of the recovered CO ₂ also decreases. In addition, if there is a distribution of temperature, concentration, flow velocity, etc. in the gas flow path of the combustor 5 or the exhaust heat recovery boiler 19, etc., there will be a region where the reaction proceeds and a region where the reaction does not occur, and the remaining CO and O ₂ will remain. The possibility increases. Further, if the dilution gas is partially reduced to create a local high-temperature combustion region in the combustor 5 in order to perform stable combustion, there is a possibility that the remaining CO and O ₂ further increase. FIG. 8 is a characteristic diagram showing the results of the chemical equilibrium calculation under the conditions in Table 1. As is clear from this figure, in the high-temperature combustion region where the equilibrium composition of CO and O ₂ is 1600 ° C. or higher. This is because it increases rapidly.

Furthermore, in the CO ₂ recovery type closed cycle coal gasification power generation system as described above, NH ₃ is generated when a hydrocarbon-based fuel containing a nitrogen-containing compound such as coal or petroleum coke is used as the gasification fuel. NH ₃ is converted to NO _X by the combustor 5, partly separated by the brackish water separators 10 and 13, converted to nitric acid, and discharged as waste water, neutralization is required. The remaining NO _X is included in the CO ₂ to be recovered or is circulated and supplied to the combustor 5.

In view of the above prior art, the present invention reliably prevents the increase of residual CO and residual O ₂ , improves the thermal efficiency and CO ₂ recovery rate, and further removes NO _X that causes environmental burdens in a dry manner. An object of the present invention is to provide a CO ₂ recovery type closed cycle gasification power generation system capable of reducing wastewater treatment.

The first aspect of the present invention for achieving the above object is as follows:
Hydrocarbon fuel including coal and heavy oil and oxygen generated in oxygen production facility are supplied to generate gasification gas, and combustion gas is generated using the gasification gas as fuel. A combustor, a gas turbine driven by the combustion gas to drive a generator, and compressing a portion of the exhaust gas of the gas turbine and mixing the compressed exhaust gas with a portion of oxygen produced by the oxygen production facility And a compressor that compresses the exhaust gas from the gas turbine and supplies a part of the exhaust gas to the carbon dioxide recovery device, and returns the remaining exhaust gas to the gasification facility. In a CO ₂ recovery type closed cycle gasification power generation system having
Upstream of the compressor and other compressor, downstream of the gas turbine, CO _2, characterized in that disposed a catalytic combustion apparatus for reacting unburned CO, and O ₂ in the flue gas Recoverable closed cycle gasification power generation system.

The second aspect of the present invention is:
In the CO ₂ recovery type closed cycle gasification power generation system described in the first aspect,
A CO ₂ recovery type closed cycle gas in which a catalytic combustion apparatus is integrally incorporated in an exhaust heat recovery boiler disposed upstream of the compressor and other compressors and downstream of the gas turbine. In the power generation system.

Then, hydrocarbon fuel containing coal and heavy oil, oxygen generated in the oxygen production facility is supplied to generate gasification gas, and combustion gas is generated using the gasification gas as fuel. A combustor to be generated; a gas turbine driven by the combustion gas to drive a generator; and a part of the oxygen generated by the oxygen production facility by compressing a part of the exhaust gas of the gas turbine and compressing the compressed exhaust gas A compressor that mixes and returns to the combustor, compresses the exhaust gas of the gas turbine and supplies a part of the exhaust gas to the carbon dioxide recovery device, and returns the remaining exhaust gas to the gasification facility In a CO ₂ recovery type closed cycle gasification power generation system having a compressor,
A reheater is disposed upstream of the compressor and other compressors and downstream of the gas turbine;
The reheater has a denitration catalyst and a combustion catalyst sequentially arranged from the upstream side, and supplies the gasification gas from the gasification facility together with the exhaust gas from the gas turbine to the denitration catalyst. Can be configured .

In the CO ₂ recovery type closed cycle gasification power generation system,
A reheat gas turbine driven by the exhaust gas of the reheater may be further arranged on the upstream side of the compressor and other compressors and on the downstream side of the reheater .

In the CO ₂ recovery type closed cycle gasification power generation system,
The reheater, a space portion is provided may Rukoto downstream of the combustion catalyst.

According to the present invention, the CO ₂ recovering closed-cycle gasification power generation system, since the arranged catalytic combustion equipment on the downstream side of the gas turbine, by reacting CO and O ₂ of the unreacted gas discharged from the gas turbine It may be converted to CO _2. As a result, the heat at the time of conversion to CO ₂ can be appropriately used to improve the thermal efficiency, and the CO ₂ recovery rate can be improved.

In addition, when a reheater having a denitration catalyst and a combustion catalyst is provided, the gasification fuel supplied to the combustor is reduced by supplying a part of the gasification fuel to the reheater, and O ₂ is reduced. Combustion can be performed in a sufficiently existing state, and unreacted CO discharged from the combustor can be reduced. Further, NO _X discharged from the combustor and NH ₃ in the fuel supplied to the reheater can be reacted with a denitration catalyst to be converted to N ₂ , thereby removing NO _X and NH _3. And reacting unreacted CO and O ₂ discharged from the combustor and fuel supplied to the reheater with a combustion catalyst to convert CO and H ₂ into CO ₂ and H ₂ O. it can. As a result, not only can improve the improvement and CO ₂ recovery of heat efficiency by appropriately utilizing the conversion time of heat CO _2, it can be properly removed NO _X dry.

1 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to a first embodiment of the present invention. The CO ₂ recovery type closed cycle coal gasification power generation system according to a second embodiment of the present invention is a block diagram showing. It is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to the reference example 1. It is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to the reference example 2. It is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to the reference example 3. It is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to Reference Example 4. It is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to the prior art. It is a characteristic view which shows the result of having performed the chemical equilibrium calculation on the conditions of Table 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to a first embodiment of the present invention. As shown in the figure, the basic configuration of the CO ₂ recovery type closed cycle coal gasification power generation system I (hereinafter also referred to as system I) according to this embodiment is the CO ₂ recovery type closed cycle coal shown in FIG. Similar to the gasification power generation system VII, a catalytic combustion device 31 is additionally provided.

  That is, the system I according to the present embodiment is generated by coal as fuel, coal gasification facility 1 that is supplied with oxygen generated in the oxygen production facility 2 and generates coal gas, and the coal gasification facility 1. It has a combustor 5 that generates combustion gas using coal gas purified by the metal filter 3 and the dry desulfurizer 4 as fuel, and a gas turbine 6 that is driven by the combustion gas and drives a generator 7.

  A catalytic combustion device 31 is disposed downstream of the gas turbine 6 and upstream of the exhaust heat recovery boiler 19 and the compressor 8. Here, as the combustion catalyst, a known catalyst (a catalyst including at least one element (atomic numbers 21 to 29, 39 to 47, 57 to 79) among transition elements excluding actinides) can be applied. Further, the inlet temperature of the catalytic combustion device 31 is preferably 500 to 800 ° C. in which catalytic combustion is promoted and the efficiency of the exhaust heat recovery boiler 19 is improved.

  The compressor 8 of the present embodiment works with the gas turbine 6, compresses a part of the exhaust gas after the exhaust heat is recovered by the exhaust heat recovery boiler 19 after predetermined combustion is performed by the catalytic combustion device 31. The compressed exhaust gas is mixed with a part of the oxygen generated in the oxygen production facility 2, and is heated by the regenerative heat exchanger 9 using the heat of the exhaust gas and returned to the combustor 5. Thus, in the combustor 5, coal gas, which is fuel, is combusted by a mixed gas of a part of oxygen generated in the oxygen production facility 2 and the exhaust gas compressed by the compressor 8. This improves the efficiency of the system I.

In the system I, the halogen in the exhaust gas of the gas turbine 6 is removed by the water washing tower of the brackish water separator 10, and the exhaust gas is further compressed by the compressor 11, and then the mercury is removed by the mercury removing unit 12. The water is separated by the brackish water separator 13 and supplied to the compressor 14. In the compressor 14, a part of the compressed exhaust gas is supplied to the CO ₂ recovery device 16 through the compressor 15, and the remaining part is returned to the coal gasification facility 1. Thereby, the gasification efficiency of coal gas in the coal gasification facility 1 is improved, and more CO is generated.

  In the system I, the steam turbine 17 is driven using the heat of the exhaust gas worked by the gas turbine 6, and the steam turbine 17 drives the generator 18. That is, the system I is constructed as a combined power generation system. Therefore, on the downstream side of the gas turbine 6, an exhaust heat recovery boiler 19 and a heat exchanger 20 that recover the heat of the exhaust gas of the gas turbine 6 are arranged. Has been. Thus, the steam that has worked in the steam turbine 17 is condensed in the condenser 21 to become water, and is supplied to the exhaust heat recovery boiler 19 through the heat exchanger 20 by the condensate pump, and becomes steam to become the steam turbine 17. To be supplied.

In this embodiment, in the catalytic combustion device 31, unburned CO and O ₂ in the exhaust gas discharged from the gas turbine 6 react and are converted to CO ₂ . That is, it is possible to reduce as much as possible the inconvenience of lowering the thermal efficiency and lowering the CO ₂ recovery rate when unburned CO and unreacted O ₂ remain in the exhaust gas discharged from the gas turbine 6. it can. Further, since unburned CO and O ₂ can be reacted on the downstream side of the gas turbine 6, the amount of O ₂ mixed with the exhaust gas compressed by the compressor 8 and supplied to the combustor 5 is also possible. Can be reduced. The reaction formula in the catalytic combustion device 31 at this time is CO + (1/2) O ₂ → CO ₂ .

In addition, although the system I which concerns on this form is a case where the coal gasification gas produced | generated with the coal gasification equipment 1 is made into the fuel of the combustor 5, it does not restrict to this. In addition, if it is gasification gas which gasified hydrocarbon fuels, such as heavy oil and biomass, it can utilize as a similar fuel. Further, the system I according to the present embodiment is a case where the system is constructed as a combined power generation system, but is not limited thereto. The utilization mode of the heat energy of the exhaust gas of the gas turbine 6 is arbitrary. The fuel limitation and the form of the power generation equipment are exactly the same in the second embodiment described below and the forms of Reference Examples 1 to 4 .

<Second Embodiment>
FIG. 2 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to a second embodiment of the present invention. As shown in the figure, the basic configuration of the CO ₂ recovery type closed cycle coal gasification power generation system II (hereinafter also referred to as system II) according to the present embodiment is the same as the system I shown in FIG. Therefore, the same parts as those in FIG.

In the system II according to the present embodiment, a catalytic combustion apparatus 41 that combusts unburned CO in the exhaust gas of the gas turbine 6 with residual O ₂ is disposed between the exhaust heat recovery boilers 19A and 19B divided into two.

In the system II of this embodiment, as in the system I, unburned CO and unreacted O ₂ in the exhaust gas are reacted in the catalytic combustion device 41 and converted to CO ₂ . The inlet temperature of the catalytic combustion apparatus 41 in this embodiment is preferably 300 to 800 ° C. at which catalytic combustion is promoted.

<Form of Reference Example 1 >
FIG. 3 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to Reference Example 1 . As shown in the figure, the basic configuration of a CO ₂ recovery type closed cycle coal gasification power generation system III (hereinafter also referred to as system III) according to the present embodiment is the same as the system I shown in FIG. Therefore, the same parts as those in FIG.

  In the system III according to this embodiment, a reheater 51 and a reheat gas turbine 52 driven by exhaust gas heated by the reheater 51 are arranged in series on the downstream side of the gas turbine 6. The reheat gas turbine 52 is configured to drive the generator 53, and the reheat gas turbine 52 also collects thermal energy and contributes to improvement of power generation efficiency in the entire system III.

  The reheater 51 includes a denitration catalyst 51A and a combustion catalyst 51B that are sequentially arranged from the upstream side. Here, along with the exhaust gas of the gas turbine 6, a part of the coal gasification gas that is the fuel supplied to the combustor 5 is dividedly supplied to the denitration catalyst 51 </ b> A via a flow rate adjustment valve (not shown). Although not shown, mixing means such as a space or a mixer is disposed upstream of the denitration catalyst 51A in order to mix the exhaust gas and the coal gasification gas of the fuel and supply them to the denitration catalyst 51A.

With the above configuration, by supplying a part of the gasified fuel to the reheater 51, the gasified fuel supplied to the combustor 5 can be reduced, and combustion can be performed in a state where O ₂ is sufficiently present. Unreacted CO discharged from 5 can be reduced.

In the combustor 5, NO _X is generated from NH ₃ contained in the fuel coal gasification gas, and it is necessary to process it. In this embodiment, the reheater 51 is composed of the denitration catalyst 51A and the combustion catalyst 51B, and the denitration catalyst 51A is disposed upstream of the combustion catalyst 51B. NO _X contained in the exhaust gas can be reacted with NH ₃ in the fuel supplied to the reheater 51 to be converted into N ₂ . As a result, NO _X and NH ₃ are removed.

On the other hand, in the combustion catalyst 51B, unreacted CO and O ₂ discharged from the combustor 5 and contained in the exhaust gas of the gas turbine 6 react with the fuel supplied to the reheater 51, and CO and H ₂ are reacted. Convert to CO ₂ and H ₂ O.

Application of a known catalyst (a catalyst containing at least one element (atomic numbers 21 to 29, 39 to 47, 57 to 79) among transition elements excluding actinides) as the denitration catalyst 51A and the combustion catalyst 51B in this embodiment Is possible. The inlet temperature of the reheater 51 is preferably 500 to 800 ° C. in which the denitration reaction and catalytic combustion are promoted, but the NO _x generation reaction is suppressed and the efficiency of the gas turbine 6 is improved. On the other hand, the outlet temperature of the reheater 51 is preferably 1500 ° C. or less at which the NO _x production reaction is suppressed and the efficiency of the gas turbine 6 is improved while the production reaction of N ₂ and H ₂ O is promoted.
The reaction formula in each part in this embodiment is as follows.
Reaction formula in the combustor 5: NH ₃ + (5/4) · O ₂ → NO + (3/2) · H ₂ O
Reaction formula in the denitration catalyst 51A: NO + NH ₃ + (1/4) · O ₂ → N ₂ + (3/2) · H ₂ O
Reaction formula in the combustion catalyst 51B: NH ₃ + (3/4) · O ₂ → (1/2) · N ₂ + (3/2) · H ₂ O

<Form of Reference Example 2 >
FIG. 4 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to Reference Example 2 . As shown in the figure, the CO ₂ recovery type closed cycle coal gasification power generation system IV (hereinafter also referred to as system IV) according to this embodiment is different in the configuration of the reheater 61 from the system III shown in FIG. . In the reheater 61 in this embodiment, a space 61C is formed following the denitration catalyst 61A and the combustion catalyst 61B in order from the upstream side. Other configurations are the same as those of the system III shown in FIG. Therefore, the same parts as those in the system III shown in FIG.

  In this embodiment, the same operation and effect as in the system III can be obtained. However, according to this embodiment, the unreacted CO contained in the exhaust gas of the gas turbine 6 and the reheater 61 are further added by the combustion catalyst 61B. A part of the supplied coal gasification gas is combusted, the gas temperature at the combustion catalyst outlet is raised to a temperature at which gas phase combustion is possible, and the remaining unreacted CO and coal gasification gas in the space 61C at the combustion catalyst outlet Can be vapor-phase combusted. By performing such gas phase combustion, the catalyst can be used at a lower temperature without increasing the temperature of the catalyst to, for example, about 1500 ° C. while achieving complete combustion of CO and coal gasification gas at the space portion outlet. Therefore, deterioration of the catalyst can be suppressed. Incidentally, deterioration such as sintering is promoted as the temperature of the catalyst increases.

<Form of Reference Example 3 >
FIG. 5 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to Reference Example 3 . As shown in the figure, the CO ₂ recovery type closed cycle coal gasification power generation system V (hereinafter also referred to as system V) according to the present embodiment omits the reheat gas turbine 52 of the system III shown in FIG. The exhaust gas from the reheater 51 is directly supplied to the exhaust heat recovery boiler 19.

  Even with the system V having such a configuration, the power generation efficiency is slightly inferior, but the same operation and effect as the system III can be exhibited.

  In FIG. 5, the same parts as those in FIG.

<Form of Reference Example 4 >
FIG. 6 is a block diagram showing a CO ₂ recovery type closed cycle coal gasification power generation system according to Reference Example 4 . As shown in the figure, the CO ₂ recovery type closed cycle coal gasification power generation system VI (hereinafter also referred to as system VI) according to the present embodiment omits the reheat gas turbine 52 of the system IV shown in FIG. The exhaust gas from the reheater 61 is directly supplied to the exhaust heat recovery boiler 19.

  Even with the system VI having such a configuration, the power generation efficiency is slightly inferior, but the same operation and effect as the system IV can be exhibited.

  In FIG. 6, the same parts as those in FIG.

The present invention can be effectively applied to an industrial field such as power generation in which it is necessary to use the motive power of the turbine and at the same time prevent CO ₂ emission to the outside air.

I, II, III, IV, V, VI CO ₂ recovery type closed cycle coal gasification power generation system 1 Coal gasification facility 2 Oxygen production facility 5 Combustor 6 Gas turbine 8 Compressor 14 (Other) Compressor 16 CO ₂ Recovery device 31, 41 Catalytic combustion device 51, 61 Reheater 51A, 61A Denitration catalyst 51B, 61B Combustion catalyst 61C Space

Claims (2)

Hydrocarbon fuel including coal and heavy oil and oxygen generated in oxygen production facility are supplied to generate gasification gas, and combustion gas is generated using the gasification gas as fuel. A combustor, a gas turbine driven by the combustion gas to drive a generator, and compressing a portion of the exhaust gas of the gas turbine and mixing the compressed exhaust gas with a portion of oxygen produced by the oxygen production facility And a compressor that compresses the exhaust gas from the gas turbine and supplies a part of the exhaust gas to the carbon dioxide recovery device, and returns the remaining exhaust gas to the gasification facility. In a CO ₂ recovery type closed cycle gasification power generation system having
Upstream of the compressor and other compressor, downstream of the gas turbine, CO _2, characterized in that disposed a catalytic combustion apparatus for reacting unburned CO, and O ₂ in the flue gas Recoverable closed-cycle gasification power generation system. In the CO ₂ recovery type closed cycle gasification power generation system according to claim 1,
A CO ₂ recovery type closed cycle gas in which a catalytic combustion apparatus is integrally incorporated in an exhaust heat recovery boiler disposed upstream of the compressor and other compressors and downstream of the gas turbine. Power generation system.