JP4681460B2 - Gasification combined power generation facility - Google Patents

Description

  The present invention relates to a combined gasification power generation facility including a gas turbine that is operated using gasified gas obtained by gasifying coal, heavy oil, or the like as fuel.

  Conventionally, there is known a combined gasification power generation facility including a gas turbine that is operated using gasified gas obtained by gasifying coal, heavy oil, or the like as fuel. This combined gasification power generation facility generates power by driving a generator with a shaft output of a gas turbine obtained by burning gasification gas, and introduces the exhaust gas of the gas turbine into an exhaust heat recovery boiler (HRSG) to generate steam. The steam turbine is operated with this steam to generate electricity.

In such a combined gasification power generation facility, ammonia (NH ₃ ) is contained in a gasification gas obtained by gasifying coal, heavy oil, or the like. Since this ammonia increases nitrogen oxide (NOx) generated in the combustion process of the gas turbine, it is desirable to remove it for the purpose of preventing the environmental degradation. That is, thermal NOx and fuel NOx are conventionally known as NOx generated in the combustion process of the gas turbine, and ammonia in the gasification gas becomes a factor that increases fuel NOx.
Therefore, a wet gas purification method including a water washing step and an ammonia treatment step has been proposed as a gas purification method for removing ammonia contained in a gasification gas obtained by gasifying coal, heavy oil, or the like. (For example, see Patent Document 1)

Here, with respect to the conventional combined gasification power generation facility, a configuration example in which ammonia in the gasification gas is removed by wet processing (water washing) will be briefly described with reference to FIG.
In FIG. 5, the gasified gas obtained by gasifying coal, heavy oil or the like in the gasification furnace 1 has water-soluble components such as ammonia and chlorine in the gas in the wet ammonia removal step (water washing step) 2. It is dissolved and removed. Thereafter, the sulfur component in the gas is removed from the gasification gas in the desulfurization step 3 and supplied to the gas turbine 4 as a fuel gas.

High-temperature (about 500 to 600 ° C.) exhaust gas discharged from the gas turbine 4 is introduced into an exhaust heat recovery boiler (HRSG) 5 to generate steam, and then exhausted as exhaust heat recovery boiler exhaust gas whose temperature has decreased. The The exhaust heat recovery boiler 5 includes a denitration device (SCR) 6 for reducing NOx as necessary. The NO decomposition reaction in the denitration device 6 is as follows.
4NH ₃ + 4NO + O ₂ → 4N ₂ + 6H ₂ O
In addition, the code | symbol 7 in a figure is an ammonia supply apparatus for supplying ammonia to the denitration apparatus 6. FIG.

On the other hand, the water that has absorbed the ammonia component and the like in the wet ammonia removal step 2 is discharged into the ammonia stripper 8 that performs ammonia stripping processing in the next step as ammonia water. The ammonia water led to the ammonia stripper 8 is recovered by heating and then sent to the ammonia incinerator 9 in the next step for incineration.
JP 2004-067849 A (refer to page 2-6, FIG. 1)

According to the above-described conventional technology, the ammonia component contained in the gasification gas is removed by wet processing, so that the problem that the fuel NOx generated in the combustion process of the gas turbine 4 increases is solved.
However, the ammonia component contained in the gasification gas is removed by a wet process and recovered as ammonia water, and then further recovered as ammonia by a stripping process before incineration. For this reason, ammonia is injected (SCR) in the denitration device 6 as a measure for reducing NOx generated by the incineration of ammonia and reducing thermal NOx generated in the combustion process of the gas turbine 4.

Further, in order to reduce ammonia in the gasified gas, there are cases where the ammonia component is removed by a wet process called acidic absorbent cleaning, and the ammonia component recovered by this wet process is recovered as a byproduct (ammonium sulfate). However, this wet treatment requires an acidic absorbent (pH adjuster: sulfuric acid), and further requires ammonia injection (SCR) as a countermeasure to reduce thermal NOx generated in the combustion process of the gas turbine.
Accordingly, the ammonia component in the gasification gas is recovered and incinerated, while ammonia for NOx reduction is injected into the denitration device 6 of the exhaust heat recovery boiler 5 to reduce thermal NOx.

As described above, in the conventional combined gasification power generation facility, not only the ammonia component contained in the generated gasification gas is incinerated to generate NOx but also separately prepared by purchasing ammonia for NOx reduction. There was a need to do. Therefore, it is desired to effectively use the ammonia component contained in the generated gasification gas in order to further improve the environmental performance and economic efficiency of the gasification combined power generation facility.
The present invention has been made in view of the above circumstances, and its object is to further improve environmental performance and economic efficiency by effectively using the ammonia component contained in the generated gasification gas. It is to provide a gasification combined power generation facility.

In order to solve the above problems, the present invention employs the following means.
A gasification combined power generation facility according to the present invention is a gasification combined power generation facility including a gas turbine that operates by using gasified gas obtained by wet purification as a fuel, and is removed from the gasification gas by a wet process. The denitration device in the exhaust heat recovery boiler in which the ammonia recovered by stripping is used as ammonia for reducing nitrogen oxide (NOx) contained in the combustion gas of the gas turbine, and the ammonia for reduction introduces the combustion gas And the amount of ammonia in the stripping recovery is controlled by adjusting the heating amount of the stripping recovery means according to the nitrogen oxide concentration of the exhaust gas discharged from the exhaust heat recovery boiler, and the exhaust heat recovery boiler Makeup water that variably controls the amount of water supplied to the stripping recovery means according to the nitrogen oxide concentration of the exhaust gas discharged from A control means is provided .

According to such a combined gasification power generation facility of the present invention, ammonia (ammonia gas or ammonia water) removed from the gasification gas by wet processing and stripped and recovered is nitrogen oxide contained in the combustion gas of the gas turbine. The ammonia for reduction is supplied to the denitration device in the exhaust heat recovery boiler that introduces combustion gas, and the amount of ammonia in the stripping recovery is the nitrogen oxidation of the exhaust gas discharged from the exhaust heat recovery boiler Supply water that is controlled by adjusting the heating amount of the stripping recovery means in accordance with the concentration of substances and that variably controls the amount of water supplied to the stripping recovery means in accordance with the nitrogen oxide concentration of the exhaust gas discharged from the exhaust heat recovery boiler is provided with the control means, together with the incineration process of stripping the recovered ammonia is not required, purchased separately Which was the procurement of reduction for ammonia also becomes unnecessary.

Then, reducing ammonia is supplied to the denitration device in the exhaust heat recovery boiler that introduces combustion gas, and the amount of ammonia in the stripping recovery is stripping according to the nitrogen oxide concentration of the exhaust gas discharged from the exhaust heat recovery boiler Since it is controlled by adjusting the heating amount of the recovery means, the heating amount of the stripping recovery means is adjusted according to the nitrogen oxide concentration actually discharged, and the amount of ammonia for stripping recovery can be optimized.
Further, the makeup water control means variably controls the amount of water supplied to the stripping recovery means according to the nitrogen oxide concentration of the exhaust gas discharged from the exhaust heat recovery boiler, so surplus ammonia is generated in the stripping recovery ammonia quantity. Control that does not occur is possible.

In the above invention, it is preferable to provide surplus ammonia treatment means by branching from the line for supplying the reducing ammonia to the denitration device, thereby improving the controllability of the ammonia amount to be stripped and recovered.
Suitable surplus ammonia treatment means in this case include ammonia incineration treatment that can decompose nitrogen oxides generated during incineration treatment using surplus ammonia, and an ammonia decomposition catalyst that eliminates the need for an incinerator for surplus ammonia. As the ammonia decomposition catalyst, a nickel-based catalyst is suitable, and as a heat source for ensuring the temperature of use conditions, for example, partial combustion of surplus ammonia or exhaust heat utilization such as a gas turbine or an exhaust heat recovery boiler can be used. is there.

  In the above invention, it is preferable to provide a distribution amount control means in a flow path for guiding the surplus ammonia to the ammonia treatment means, thereby improving controllability with respect to NOx fluctuation.

According to the present invention described above, ammonia removed from the gasification gas such as coal and heavy oil by wet treatment and recovered by stripping is used as ammonia for reducing nitrogen oxide contained in the combustion gas of the gas turbine , By providing a makeup water control means that variably controls the amount of water supplied to the stripping recovery, it is not necessary to incinerate the stripped recovered ammonia or to purchase separately purchased reducing ammonia. The ammonia component contained in the gas) can be used effectively. As a result, not only does the emission of nitrogen oxides decrease and the environmental performance improves, but it also eliminates the need to purchase ammonia for the reduction of nitrogen oxides, improving the economics of reducing operating costs. A remarkable effect is obtained that it is possible to provide a gasification combined power generation facility with further improved economic efficiency.

Hereinafter, an embodiment of a combined gasification power generation facility according to the present invention will be described with reference to the drawings.
<First Embodiment>
In the first embodiment shown in FIG. 1, the gasification furnace 1 is an apparatus that generates gasified gas by gasifying coal, heavy oil, or the like. The gasification gas generated in the gasification furnace 1 is sent to a wet ammonia removal step (water washing step) 2 where water-soluble components such as ammonia and chlorine in the gas are dissolved and removed in water. Then, gasification gas is sent to the desulfurization process 3, and the sulfur component in gas is removed. Thus, the gasification gas from which water-soluble components, such as ammonia, and sulfur content were removed is supplied to the gas turbine 4 as fuel gas.

The gasification gas supplied to the gas turbine 4 is burned in a combustor (not shown) to become a high-temperature and high-pressure combustion gas, and is discharged as a high-temperature (about 500 to 600 ° C.) exhaust gas after driving the turbine body. . This exhaust gas is introduced into an exhaust heat recovery boiler (HRSG) 5.
The exhaust heat recovery boiler 5 is a device that generates steam by recovering the heat held in the exhaust gas, and the steam generated by the exhaust heat recovery boiler 5 is supplied to a steam turbine (not shown). On the other hand, the exhaust gas whose exhaust heat has been recovered by the exhaust heat recovery boiler 5 is discharged as exhaust heat recovery boiler exhaust gas whose temperature has dropped. In order to measure the nitrogen oxide (NOx) concentration of the exhaust heat recovery boiler exhaust gas, a NOx concentration meter 11 is installed at an appropriate location downstream of the exhaust heat recovery boiler 5.

Further, the exhaust heat recovery boiler 5 is provided with a denitration device (SCR) 6 for introducing ammonia to reduce NOx. NOx to be denitrated here
Is generated in the combustion process of the gas turbine 4 and is included in the combustion gas, and fuel NOx caused by nitrogen such as ammonia remaining without being removed in the wet ammonia removal step 2
And thermal NOx resulting from the nitrogen content of the combustion air. Note that the NO decomposition reaction in the denitration apparatus 6 is the same as the conventional one.

On the other hand, the water that has absorbed the ammonia component or the like in the wet ammonia removal step 2 is converted into ammonia water and introduced into the ammonia stripper 8 of the stripping recovery means for performing the stripping process in the next step. In the ammonia stripper 8, ammonia water is heated by the stripper heater 12 to recover ammonia, and this ammonia is supplied to the above-described denitration device 6. That is, the ammonia recovered from the gasification gas is used as NOx reduction ammonia contained in the combustion gas of the gas turbine 4. The ammonia for NOx reduction used here may be either ammonia water or ammonia gas.
The amount of ammonia supplied for NOx reduction supplied from the ammonia stripper 8 to the denitration device 6 is NOx.
In accordance with the NOx concentration of the exhaust heat recovery boiler exhaust gas measured by the densitometer 11, the heating amount of the stripper heater 12 is adjusted and controlled.

More specifically, the NOx concentration actually measured is measured by the NOx concentration meter 11.
Based on the actual measurement value, control is performed as follows.
When the actual measured value of NOx changes to the high concentration side, the heating amount of the stripper heater 12 is increased, and the amount of ammonia supplied from the ammonia stripper 8 to the denitration device 6 is increased. As a result, the amount of ammonia for reduction in the denitration device 6 increases, so NOx
As a result, the amount of NOx discharged together with the exhaust heat recovery boiler exhaust gas is reduced. When the actual measured value of NOx fluctuates to the low concentration side, the heating amount of the stripper heater 12 is reduced, and the amount of ammonia supplied from the ammonia stripper 8 to the denitration device 6 is reduced to suppress the generation of surplus ammonia.

As described above, since the ammonia recovered from the gasification gas is effectively used and used as ammonia for reducing NOx contained in the combustion gas of the gas turbine 4, the ammonia in the combustion gas discharged from the gas turbine 4 is used. The amount of NOx can be reduced and the environmental performance can be improved. Here, NOx contained in the combustion gas of the gas turbine 4
The reducing ammonia necessary for the treatment can be recovered and obtained from the gasification gas without purchasing it separately, so that it is possible to contribute to the improvement of economy by reducing the running cost necessary for the operation.
In addition, since the incineration facility for ammonia incineration processing (ammonia incinerator 9 shown in FIG. 5), which has been necessary in the past, becomes unnecessary, the problem of NOx generated during ammonia incineration can be solved.

<Second Embodiment>
Then, 2nd Embodiment is described based on FIG. 2 about the gasification combined cycle power generation equipment which concerns on this invention. In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and the detailed description is abbreviate | omitted.
In this embodiment, an ammonia incineration treatment facility serving as surplus ammonia treatment means is provided by branching from a line for supplying ammonia for reduction from the ammonia stripper 8 to the denitration device 6. This surplus ammonia treatment means incinerates the surplus ammonia recovered.

The surplus ammonia treatment means by the ammonia incineration treatment is provided with a piping system branching from the piping for supplying ammonia from the ammonia stripper 8 to the denitration device 6, and the ammonia incineration treatment device 9A and the exhaust heat recovery boiler 5A for ammonia incineration treatment are provided. It is a thing. This ammonia incineration waste heat recovery boiler 5A is provided with an ammonia incineration denitration device (SCR) 6A for treating NOx generated when ammonia is incinerated by the ammonia incineration unit 9A. The ammonia incineration denitration device (SCR) 6A is smaller than the denitration device 6 of the exhaust heat recovery boiler 5 that processes the exhaust gas of the gas turbine 4 described above. A part of ammonia may be introduced and used.
In addition, a valve (not shown) that adjusts the opening degree in conjunction with the measured value of the NOx concentration meter 11 and the heating amount of the stripper heater 12 is provided at an appropriate position on the line for supplying ammonia from the ammonia stripper 8 to distribute excess ammonia. It is preferred to control the amount. This valve functions as a distribution amount control means provided in a flow path for introducing surplus ammonia to the ammonia incineration apparatus 9A.

With such a configuration, the ammonia amount obtained by heating the ammonia water introduced from the wet ammonia removal step 2 with the stripper heater 12 depends on the NOx concentration of the exhaust heat recovery boiler exhaust gas measured by the NOx concentration meter 11. Then, the amount of heating of the stripper heater 12 is adjusted and controlled. However, when surplus ammonia exceeding the required amount of the denitration device 6 is generated, the ammonia is incinerated by diverting it to the ammonia incinerator 9A side. be able to.
When surplus ammonia is incinerated by this ammonia incinerator 9A, NOx is generated.
After being reduced by the denitration device 6A for ammonia incineration, it is discharged as exhaust heat recovery boiler exhaust gas from the ammonia incineration exhaust heat recovery boiler 5A. Further, the reducing ammonia gas required in the denitration device 6A for ammonia incineration treatment does not need to be purchased separately because a part of the surplus ammonia may be used.

  Accordingly, the amount of ammonia is controlled by adjusting the heating amount of the stripper heater 12 and, when surplus ammonia is generated, it is possible to perform incineration treatment. As a result, the controllability can be improved. Further, by providing a valve whose opening degree can be adjusted in conjunction with the measured value of the NOx concentration meter 11 and the heating amount of the stripper heater 12, controllability (dynamic characteristics) with respect to NOx fluctuation is further improved. The improvement in environmental performance and economic efficiency is the same as in the first embodiment described above.

Subsequently, a modification according to the second embodiment described above will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the component similar to 1st and 2nd embodiment mentioned above, and the detailed description is abbreviate | omitted.
In this modification, an ammonia decomposition catalyst 20 is provided which is branched from a line for supplying reducing ammonia from the ammonia stripper 8 to the denitration device 6 and serves as surplus ammonia treatment means. The ammonia decomposition catalyst 20 is a catalyst that decomposes the surplus of recovered ammonia with a catalyst.
Also in this embodiment, a valve (not shown) for adjusting the opening degree in conjunction with the measured value of the NOx concentration meter 11 and the heating amount of the stripper heater 12 is provided at an appropriate position on the line for supplying ammonia gas from the ammonia stripper 8. It is preferable to control the distribution amount of surplus ammonia. This valve functions as a distribution amount control means provided in a flow path for guiding excess ammonia to the ammonia decomposition catalyst 20.

As the ammonia decomposition catalyst used here, a nickel-based catalyst is suitable. Since the ammonia decomposition reaction of the nickel-based catalyst is an endothermic reaction, it is necessary to decompose at a high temperature (about 750 to 1200 ° C.) in order to reduce the amount of residual ammonia. As this heat source, a part of surplus ammonia may be burned, or exhaust heat may be introduced from the gas turbine 4 or the exhaust heat recovery boiler 5 to be used.
With such a configuration, surplus ammonia can be treated without using an incineration treatment apparatus for ammonia incineration that generates NOx. Therefore, the amount of ammonia is adjusted by adjusting the heating amount of the stripper heater 12. In addition, when surplus ammonia is generated, the catalyst can be decomposed, so that the amount of surplus ammonia can be adjusted and the degree of freedom in control of the treatment can be increased to improve controllability.

<Third Embodiment>
Then, 3rd Embodiment is described based on FIG. 4 about the gasification combined cycle power generation equipment which concerns on this invention. In addition, the same code | symbol is attached | subjected to the component similar to each embodiment mentioned above, and the detailed description is abbreviate | omitted.
In this embodiment, makeup water control means for variably controlling the amount of water supplied to the wet ammonia removal step 2 according to the NOx concentration of the exhaust heat recovery boiler exhaust gas discharged from the exhaust heat recovery boiler 5 is provided.
More specifically, a flow rate control valve 31 is provided in the makeup water pipe 30 for supplying makeup water to the wet ammonia removal step 2, and the amount of the makeup water is variably controlled by adjusting the opening of the flow rate control valve 31. . The opening degree of the flow control valve 31 is controlled together with the heating amount of the stripper heater 12 according to the NOx actual measurement value of the exhaust heat recovery boiler exhaust gas measured by the NOx concentration meter 11.

That is, when the actual measured value of NOx fluctuates to the high concentration side, the supply amount of makeup water is increased by operating the flow control valve 31 in an increasing direction. As a result, the amount of ammonia water introduced into the ammonia stripper 8 from the wet ammonia removal step 2 increases, so the amount of ammonia supplied from the ammonia stripper 8 to the denitration device 6 increases by simultaneously increasing the amount of heating of the stripper heater 12. To do. Therefore, the amount of ammonia for reduction in the denitration device 6 increases, so NOx
As a result, the NOx amount discharged together with the exhaust heat recovery boiler exhaust gas can be reduced.
On the other hand, when the actual measured value of NOx fluctuates to the low concentration side, the supply amount of makeup water is decreased by operating in the direction of decreasing the opening degree of the flow control valve 31, and the heating amount of the stripper heater 12 is also decreased. As a result, the amount of ammonia supplied from the ammonia stripper 8 to the denitration device 6 is reduced and NOx is reduced.
Decomposition ability is suppressed.

  With such a configuration, it is possible to control the recovered ammonia amount (wet water amount of the water washing tower) of the wet treatment in the wet ammonia removal step 2 to an optimum value based on the actual measured value of NOx and the required amount of reducing ammonia. Therefore, it is possible to recover an appropriate amount without excess ammonia, and therefore, it is not necessary to process excess ammonia such as incineration or decomposition using a catalyst.

As described above, according to the combined gasification power generation facility of the present invention, the nitrogen removed from the gasification gas such as coal and heavy oil by the wet treatment and stripped and recovered is contained in the combustion gas of the gas turbine 4. Because it is used as ammonia for reducing oxides, it is not necessary to incinerate stripped ammonia or to purchase separately purchased ammonia for reduction, and it is possible to effectively use the ammonia component contained in the generated gasification gas. it can. As a result, not only does the emission of nitrogen oxides decrease and the environmental performance improves, but it also eliminates the need to purchase ammonia for the reduction of nitrogen oxides, improving the economics of reducing operating costs. It becomes a gasification combined power generation facility with further improved economic efficiency.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

It is a block diagram which shows 1st Embodiment of the gasification combined cycle power generation equipment which concerns on this invention. It is a block diagram which shows 2nd Embodiment of the gasification combined cycle power generation equipment which concerns on this invention. It is a block diagram which shows the modification of the gasification combined cycle power generation equipment which concerns on 2nd Embodiment. It is a block diagram which shows 3rd Embodiment of the gasification combined cycle power generation equipment which concerns on this invention. It is a figure which shows the structure of the conventional gasification combined cycle power generation equipment.

Explanation of symbols

1 Gasification furnace 2 Wet ammonia removal process (water washing process)
3 Desulfurization process 4 Gas turbine 5 Waste heat recovery boiler (HRSG)
5A Waste heat recovery boiler for ammonia incineration (HRSG)
6 Denitration equipment (SCR)
6A Denitration equipment for ammonia incineration (SCR)
8 Ammonia stripper 9A Ammonia incinerator 11 NOx concentration meter 12 Stripper heater 20 Ammonia decomposition catalyst 30 Make-up water piping 31 Flow control valve

Claims (5)

In a combined gasification power generation facility equipped with a gas turbine that operates using gasification gas obtained by wet purification as fuel,
Ammonia removed from the gasification gas by wet treatment and recovered by stripping is used as ammonia for reducing nitrogen oxide (NOx) contained in the combustion gas of the gas turbine,
The reducing ammonia is supplied to a denitration device in the exhaust heat recovery boiler that introduces the combustion gas, and the amount of ammonia in the stripping recovery depends on the nitrogen oxide concentration of the exhaust gas discharged from the exhaust heat recovery boiler. It is controlled by adjusting the heating amount of the stripping recovery means,
A combined gasification power generation facility comprising makeup water control means for variably controlling the amount of water supplied to the stripping recovery means in accordance with the nitrogen oxide concentration of exhaust gas discharged from the exhaust heat recovery boiler . 2. The combined gasification power generation facility according to claim 1 , wherein surplus ammonia treatment means is provided by branching from a line for supplying the reducing ammonia to the denitration apparatus. The combined gasification power generation facility according to claim 2 , wherein the surplus ammonia treatment means is ammonia incineration treatment. The combined gasification power generation facility according to claim 2 , wherein the surplus ammonia treatment means is an ammonia decomposition catalyst. The combined gasification power generation facility according to any one of claims 2 to 4 , wherein a distribution amount control means is provided in a flow path for guiding the surplus ammonia to the ammonia treatment means.

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