KR20160141037A - Combined cycle power generation system - Google Patents

Abstract

Disclosed is a complex thermal power generation system. The complex thermal power generation system in accordance with the present invention uses a part of steam generated from a gas cooler for cooling gas discharged from a gasification unit as a heat source of a hydrolyzing unit that generates ammonia by hydrolyzing urea aqueous solution. Thus, since any separate heat source for decomposing urea aqueous solution is not required, manufacturing costs may be saved, and the volume of the complex thermal power generation system may be reduced. In addition, if urea aqueous solution of a storage tank in which the urea aqueous solution is stored is supplied to the hydrolyzing unit after heating the urea aqueous solution with steam discharged from the hydrolyzing unit, the freezing burst of the storage tank may be prevented. Also, since the urea aqueous solution of the storage tank is preheated and flows into the hydrolyzing unit, energy for heating the urea aqueous solution in the hydrolyzing unit may be saved.

Description

{COMBINED CYCLE POWER GENERATION SYSTEM}

The present invention relates to a combined-cycle power generation system for generating ammonia by heating a urea (Urea) aqueous solution as a part of steam generated in a gas cooler for cooling a gas produced in a gasification unit and then supplying it to a selective reduction catalyst reactor of a waste heat recovery boiler ≪ / RTI >

The combined cycle power generation system is a system in which a gas turbine is rotated by a gas generated during the combustion of fuel and is used to generate electricity by using the gas discharged from the gas turbine after the gas turbine is driven. And then the steam turbine is rotated by the steam generated in the waste heat recovery boiler to generate the secondary steam.

Combined-cycle power generation has two advantages: it improves thermal efficiency by 10%, reduces environmental pollution, and shortens restart time after shutdown. In addition, the combined cycle power plant has the advantage that the construction period of the power plant is shortened compared to the thermal power plant using coal as fuel.

Since the gas introduced into the waste heat recovery boiler from the gas turbine of the combined cycle power generation system contains nitrogen oxide which causes environmental pollution, nitrogen oxide is also contained in the next exhaust gas used for generating steam in the waste heat recovery boiler have. Therefore, nitrogen oxides contained in the exhaust gas from the waste heat recovery boiler should be removed.

One of the techniques for removing nitrogen oxides is a dry method in which ammonia is injected into nitrogen oxides at high temperatures to reduce nitrogen oxides to nitrogen and water.

In the dry method, there is a selective non-catalytic reduction method in which nitrogen oxide is selectively reduced to nitrogen and moisture without using a catalyst, and a selective catalytic reduction method in which nitrogen oxide is reduced to nitrogen and moisture while using a catalyst. The selective catalytic reduction method is widely used.

In the case of a combined-cycle power generation system that removes nitrogen oxides by the selective catalytic reduction method, ammonia is generated by heating an aqueous solution of urea (Urea) stored in the hydrolysis unit, followed by injection into a selective catalytic reduction (SCR) do.

However, in the conventional combined-cycle power generation system, a separate heat source is required in order to heat the urea aqueous solution stored in the hydrolysis unit, so that the cost increases and the volume increases.

It is an object of the present invention to provide a combined-cycle power generation system capable of solving all the problems of the conventional art as described above.

Another object of the present invention is to provide a method for producing ammonia by heating a urea aqueous solution of a hydrolysis unit as a part of vapor of a gas cooler generated when a gas produced in a gasification unit is cooled, To provide a thermal power generation system.

According to an aspect of the present invention, there is provided a combined-cycle thermal power generation system including: a gasification unit for generating a gas by burning fuel; A gas cooler for cooling the gas produced in the gasification unit; A gas turbine for supplying gas from the gas cooler and driving the gas turbine; A selective catalytic reduction catalyst for removing nitrogen oxides contained in the gas introduced into the main body when ammonia is supplied to the main body, the main catalytic reduction catalyst comprising a main body having an inlet through which the gas discharged from the gas turbine flows and a discharge outlet through which the gas is introduced, A waste heat recovery boiler having a reactor; And a hydrolysis unit provided at one side of the waste heat recovery boiler for generating ammonia supplied to the selective reduction catalytic reactor by hydrolyzing an aqueous solution of urea and Urea, A part of the generated steam may be supplied to the hydrolysis unit and used as a heat source for hydrolyzing the urea aqueous solution.

The combined-cycle power generation system according to the embodiment of the present invention uses a part of the steam generated in the gas cooler that cools the gas discharged from the gasification unit as the heat source of the hydrolysis unit that hydrolyzes the urea aqueous solution to generate ammonia. Therefore, since there is no need for a separate heat source for hydrolyzing the urea aqueous solution, the cost can be reduced and the volume can be reduced.

When the urea aqueous solution of the storage tank in which the urea aqueous solution is stored by the steam discharged from the hydrolysis unit is heated and then supplied to the hydrolysis unit, the storage tank may be prevented from being frozen.

And, since the urea aqueous solution of the storage tank is preheated and introduced into the hydrolysis unit, the energy for heating the aqueous urea solution in the hydrolysis unit may be reduced.

1 is a view showing a configuration of a combined-cycle thermal power generation system according to an embodiment of the present invention;
2 is an enlarged view of the waste heat recovery boiler shown in Fig.
3 is an enlarged view of a waste heat recovery boiler according to another embodiment of the present invention.

It should be noted that, in the specification of the present invention, the same reference numerals as in the drawings denote the same elements, but they are numbered as much as possible even if they are shown in different drawings.

Meanwhile, the meaning of the terms described in the present specification should be understood as follows.

The word " first, "" second," and the like, used to distinguish one element from another, are to be understood to include plural representations unless the context clearly dictates otherwise. The scope of the right should not be limited by these terms.

It should be understood that the terms "comprises" or "having" does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, Means any combination of items that can be presented from more than one.

The term "above" means not only when a configuration is formed directly on top of another configuration, but also when a third configuration is interposed between these configurations.

Hereinafter, a combined-cycle thermal power generation system according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a configuration of a combined-cycle thermal power generation system according to an embodiment of the present invention.

As shown, the combined-cycle power generation system 100 according to an embodiment of the present invention may include a gasification unit 110. The gasification unit 110 may combust a gaseous fuel, a liquid fuel, or a fossil fuel to generate a combustible gas.

In particular, a system that generates electricity after generating gas using coal as a fuel is called a coal gasification combined cycle power generation system. Coal may be put into slurry form or into pulverized coal form. The coal in the form of slurry is fed with water, which is an oxidant, with air or oxygen, and coal in the form of pulverized coal is fed with air or oxygen which is an oxidizing agent.

Oxygen, which is an oxidant required for combustion of coal, is generated in the air separator 120, and the air separator 120 can cool the air to generate oxygen and nitrogen. When the air is cooled to a predetermined temperature, it is separated into liquid oxygen and liquid nitrogen due to the difference in boiling point of oxygen and nitrogen. The low temperature oxygen separated from the air separator 120 can be supplied to the gasification unit 110 after heat exchange.

Since the gas generated in the gasification unit 110 is at a high temperature of 1300 ° C or higher, it is preferable that the gas is cooled to a predetermined temperature and supplied to the gas turbine 150 to be described later. A gas cooler 130 may be provided to cool the gas discharged from the gasification unit 110 and the gas cooler 130 may cool the gas discharged from the gasification unit 110 in a water-cooled manner. Then, the water of the gas cooler 130, which has exchanged heat with the gas discharged from the gasification unit 110, becomes steam and can drive the steam turbine 170, which will be described later.

The pulverized coal, which is coal, contains about 2 to 20% of coal ash, which is a non-combustible material. Approximately 20% of the coal ash is melted by the high-temperature combustion heat of the gasification unit 110, becomes a slag in which various particles are condensed, and is connected to a hopper (not shown) communicated with the lower part of the gasification unit 110, As shown in FIG. Then, the remaining approximately 80% of the coal ash is burned for each particle and scattered according to the flow of the gas, and the gas containing the coal fly ash can be refined while flowing through the refiner 140.

The purification apparatus 140 may include a dust eliminator, a hydrolyzer, an acidic gas remover, an emulsifier, and the like.

The dust eliminator can separate and remove dust including fly ash contained in the gas discharged from the gasification unit 110, and collect dust. In addition, the dust eliminator may be separated and removed by collecting dust after decompression and cooling, or may convert some of the carbonyl sulfide (COS) to hydrogen sulfide and carbon dioxide by hydrolysis.

The hydrolyzate can remove the sulfur component by hydrolyzing the dust-removed gas, and the gas from which the sulfur component has been removed from the hydrolysis unit can be introduced into the waste water processor (not shown) and treated. At this time, the wastewater treatment device can transfer the sour gas to the emitter.

The acid gas purifier may separate the sulfur-removed gas into an acid gas and a pure gas, and may transfer the acid gas to the sulfur gas. Then, the emulsifier can separate sulfur and sulfuric acid therefrom and transport tail gas (Tail Gsa) to the user.

The gas discharged from the acid gas eliminator may be supplied to a gas turbine 150 having a combustor (not shown), a compressor (not shown) and a turbine (not shown). Thus, the gas turbine 150 can drive the generator while being driven by the introduced gas. The oxygen required to burn the gas in the combustor of the gas turbine 150 may be supplied from the air separator 120.

After driving the gas turbine 150, the discharged gas may be used as a heat source to generate steam by flowing into the waste heat recovery boiler 160.

The steam generated in the waste heat recovery boiler 160 flows into the steam turbine 170 to drive the steam turbine 170 and the steam turbine 170 drives the other generator to drive the generator.

The waste heat recovery boiler 160 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 2 is an enlarged view of the waste heat recovery boiler shown in Fig.

The waste heat recovery boiler 160 according to an embodiment of the present invention may include a main body 161 and may be provided at one side and the other side of the main body 161 with gas And a discharging portion 161b formed of a chimney or the like may be respectively formed.

An economizer 162a for heating the water with residual heat of the gas flowing into the main body 161 can be installed in the main body 161 on the inflow portion 161a and the inflow portion 161a An evaporator 162b for vaporizing the water delivered from the economizer 162a may be installed in the main body 161 between the economizers 162a and the main body 161 between the inlet 161a and the evaporator 162b A superheater 162c that generates superheated steam by heating the steam delivered from the evaporator 162b may be installed.

 The superheated steam generated in the superheater 162c can generate power while the steam turbine 170 is driven.

At this time, water is stored in one side of the main body 161, and at the same time, a water tank / deaerator 164 for removing oxygen dissolved in water can be installed, and water in the water tank / deaerator 164 can be supplied to the economizer May be supplied to the first electrode 162a. The water heated by the economizer 162a can be introduced into the evaporator 162b through the drum 162d.

2, the gas flows into the right side of the main body 161 and is discharged to the left side, and water can flow in from the left side of the main body 161 and be discharged to the right side.

The above-described economizer 162a, the evaporator 162b, the superheater 162c, and the drum 162d may be installed on the inner right side of the body 161 adjacent to the inlet 161a, which is the high-pressure region 162 The evaporator 163b, the superheater 163c, and the drum 163d may be installed on the inner left side of the body 161 adjacent to the discharge portion 161b which is the low pressure region 163.

The gas flowing into the main body 161 through the inflow portion 161a may contain nitrogen oxides that cause environmental pollution. Therefore, after the nitrogen oxide contained in the gas introduced into the body 161 is removed, the gas must be discharged to the discharge portion 161b.

The waste heat recovery boiler 160 according to an embodiment of the present invention may use a selective catalytic reduction reactor 165 to remove nitrogen oxides contained in the gas. Since the optimum denitrification efficiency is generated when the temperature of the gas is 300 to 400 ° C, the selective reduction catalytic reactor 165 is installed between the superheater 162c and the evaporator 162b, the temperature of which ranges from 300 to 400 ° C. .

The selective reduction catalyst reactor 165 uses a catalyst and acts with ammonia separately supplied to reduce the nitrogen oxides contained in the gas to nitrogen and moisture. Ammonia is produced by hydrolyzing an urea (Urea) aqueous solution. A hydrolytic unit 181 for generating ammonia by hydrolyzing the urea aqueous solution may be installed at one side of the main body 161. At this time, heat is required to hydrolyze the urea aqueous solution in the hydrolysis unit 181. [

The waste heat recovery boiler 160 according to an embodiment of the present invention is a heat source for hydrolyzing the urea aqueous solution and includes a portion of the steam generated when the gas discharged from the gasification unit 110 is cooled by the gas cooler 130 Can be used.

The steam generated in the gas cooler 130 is supplied to the steam turbine 170 to drive the steam turbine 170, as described above. In order to supply a part of the steam generated in the gas cooler 130 and supplied to the steam turbine 170 to the hydrolysis unit 181, a steam branch pipe 133 is connected to one side of the steam supply pipe line 131 And a part of the steam branch passageway 133 can heat the urea aqueous solution while passing through the inside of the hydrolyzer 181. [

The ammonia produced in the hydrolysis unit 181 is injected into the selective reduction catalyst reactor 165 and the ammonia is supplied to the distribution plate 166 formed with a plurality of injection holes so that the ammonia can be uniformly injected into the selective reduction catalyst reactor 165, To the selective reduction catalytic reactor 165 via the selective reduction catalytic reactor 165.

A distribution plate 167 is installed on the side of the internal inflow portion 161a of the main body 161 so as to guide the gas introduced into the main body 161 to the side of the discharge portion 161b uniformly from the inside of the main body 161 . A burner 168 for heating the superheater 162c may be installed between the distribution plate 167 and the superheater 162c.

The waste heat recovering boiler 160 according to an embodiment of the present invention may cool the gas discharged from the gasification unit 110 to the gas cooler 130 as a heat source of the hydrolysis unit 181 that generates ammonia by hydrolyzing the urea aqueous solution Some of the vapors that are generated are used. Therefore, since a separate heat source for hydrolyzing the urea aqueous solution is not required, the cost can be reduced and the volume can be reduced.

FIG. 3 is an enlarged view of a waste heat recovery boiler according to another embodiment of the present invention, and only differences from FIG. 2 are described.

As shown, the waste heat recovery boiler 260 according to another embodiment of the present invention may further include a storage tank 283 for storing the urea aqueous solution, and the urea aqueous solution of the storage tank 283 is supplied to the hydrolyzer 281 ). ≪ / RTI >

At this time, the steam discharged after circulating the hydrolysis unit 281 can heat the urea aqueous solution of the storage tank 283. That is, one side of the steam branch passage 233 that has passed through the hydrolysis unit 281 can pass through the storage tank 283. Then, since the storage tank 283 is heated by the steam discharged from the hydrolyzer 281, it is possible to prevent the storage tank 283 from being frozen. Since the urea aqueous solution of the storage tank 283 is preheated and flows into the hydrolyzer 281, the energy for heating the aqueous urea solution in the hydrolyzer 281 can be reduced.

The superheated steam discharged from the hydrolyzer 281 may be selectively supplied to the storage tank 283. A temperature sensor 285 for sensing the temperature of the storage tank 283 may be installed at one side of the storage tank 283 and a temperature sensor 285 may be provided for controlling the temperature of the storage tank 283 by the control unit 287. [ Temperature can be transmitted.

Thus, when the temperature of the storage tank 283 is lower than the set temperature, the vapor discharged from the hydrolysis unit 281 can be supplied to the storage tank 283 under the control of the control unit 287.

The steam passing through the portion of the steam branch passage 233 passing through the hydrolyzer 281 and the steam passing through the storage tank 283 are supplied to the storage tank 283 in order to selectively supply the superheated steam discharged from the hydrolyzer 281 to the storage tank 283. [ One side and the other side of the auxiliary conduit 233a may be connected to the branch conduit 233, respectively. The superheated steam discharged from the hydrolysis unit 281 is stored in the storage tank 283 while being controlled by the control unit 287 in the portion of the steam branch passage 233 that has passed through the hydrolyzer 281 and the auxiliary pipe 233a. And valves 289a and 289b for selectively supplying the pressurized gas to the pressurized water supply unit 300. [

When the valve 289a is opened and the valve 289b is closed, superheated steam discharged from the gas decomposer 281 is supplied to the storage tank 283, and when the valve 289a is closed and the valve 289b is opened, It is a matter of course that the superheated steam discharged from the gas cracker 281 is not supplied to the storage tank 283.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Will be clear to those who have knowledge of. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention.

110: Gasification unit
130: gas cooler
150: Gas turbine
160: Waste Heat Recovery Boiler
165: selective reduction catalyst reactor
170: Steam turbine
181: Hydrolytic

Claims (4)

A gasification unit for burning fuel to generate gas;
A gas cooler for cooling the gas produced in the gasification unit;
A gas turbine for supplying gas from the gas cooler and driving the gas turbine;
A selective catalytic reduction catalyst for removing nitrogen oxides contained in the gas introduced into the main body when ammonia is supplied to the main body, the main catalytic reduction catalyst comprising a main body having an inlet through which the gas discharged from the gas turbine flows and a discharge outlet through which the gas is introduced, A waste heat recovery boiler having a reactor;
And a hydrolyzer installed at one side of the waste heat recovery boiler for generating ammonia supplied to the selective reduction catalyst reactor by hydrolyzing an aqueous urea solution,
Wherein part of the generated steam is used as a heat source for hydrolyzing the urea aqueous solution when the gas produced in the gasification unit is cooled in the gas cooler. The method according to claim 1,
Wherein a distribution plate having a plurality of injection holes through which ammonia supplied from the hydrolysis unit passes is installed at one side of the selective reduction catalyst reactor. The method according to claim 1,
Further comprising a storage tank for storing and supplying the urea aqueous solution to the hydrolyzer,
And the steam discharged from the hydrolysis unit heats the storage tank. The method of claim 3,
Wherein the storage tank is provided with a temperature sensor for sensing the temperature of the storage tank,
And the steam discharged from the hydrolysis unit is supplied to the storage tank when the temperature of the storage tank is lower than a set temperature.

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