KR102116591B1 - Heat recovery steam generator - Google Patents

Abstract

A waste heat recovery boiler is disclosed. The waste heat recovery boiler according to the present invention is a hydrolyzate that generates ammonia by hydrolyzing the aqueous urea solution, and supplies and heats part of the gas discharged from the gas turbine and introduced into the waste heat recovery boiler. Burner fuel for heating the aqueous solution can be saved. Therefore, there may be an effect of reducing the cost.

Description

Waste Heat Recovery Boiler {HEAT RECOVERY STEAM GENERATOR}

The present invention relates to a waste heat recovery boiler that supplies a part of the gas supplied to the waste heat recovery boiler with a hydrolysis machine that produces ammonia.

A waste heat recovery boiler refers to a device used to recover high-temperature gas generated during combustion of fuel and generate steam. At this time, the gas that is supplied to the waste heat recovery boiler and used to generate steam contains nitrogen oxides that cause environmental pollution. Therefore, nitrogen oxides contained in the gas discharged from the waste heat recovery boiler must be removed because the gas discharged after being used to generate steam in the waste heat recovery boiler also contains nitrogen oxide.

One of the techniques for removing nitrogen oxides is a dry method in which nitrogen oxides are reduced to nitrogen and moisture by spraying ammonia with nitrogen oxides at high temperatures.

In addition, the dry method includes a selective non-catalytic reduction method of selectively reducing nitrogen oxides to nitrogen and water without using a catalyst, and a selective catalytic reduction method of reducing nitrogen oxides to nitrogen and water while using a catalyst. Economical and technical aspects In the selective catalytic reduction method is used a lot.

A waste heat recovery boiler that removes nitrogen oxides by a selective catalytic reduction method generates ammonia by heating an aqueous solution of urea (Urea) in a hydrolyzer, and then supplies it to a selective catalytic reduction (SCR) reactor. In addition, the hydrocracker includes a chamber into which the atomized urea aqueous solution is injected and a burner that heats the chamber. When fuel is supplied from a separate fuel supply device together with air to the burner, the fuel is burned and the chamber is heated do.

The conventional waste heat recovery boiler heats the aqueous solution of urea stored in the chamber of the hydrolyzator using only the burner, and thus requires a lot of fuel for the burner. Due to this, there is a disadvantage that the cost increases.

An object of the present invention may be to provide a waste heat recovery boiler that can solve all the problems of the prior art as described above.

Another object of the present invention may be to provide a waste heat recovery boiler that can reduce costs by heating an aqueous solution of the urea in a chamber of a hydrolyzator that generates ammonia using gas supplied to a waste heat recovery boiler.

Waste heat recovery boiler according to an embodiment of the present invention for achieving the above object, the main body is formed with the inlet and the outlet gas is discharged; A superheater installed on the main body and generating superheated steam; A selective catalytic reduction reactor that is installed in the main body and removes nitrogen oxides contained in the gas introduced into the main body when ammonia is supplied; It includes a hydrolyzer to generate ammonia supplied to the selective reduction catalyst reactor while having a chamber to which the atomized aqueous urea solution is injected and a burner to heat the chamber, and a part of the gas flowing into the main body is supplied to the hydrolysis device It is possible to heat the aqueous solution of urea in the chamber.

The waste heat recovery boiler according to the embodiment of the present invention is a hydrolyzate that hydrolyzes an aqueous urea aqueous solution to produce ammonia and supplies a part of the gas discharged from the gas turbine to the waste heat recovery boiler to supply urea to the urea of the chamber Since the aqueous solution is heated, the fuel of the burner for heating the aqueous solution of urea in the chamber can be saved. Therefore, there may be an effect of reducing the cost.

1 is a view showing the configuration of a combined cycle power generation system using a waste heat recovery boiler according to a first embodiment of the present invention.
Figure 2 is an enlarged view of the waste heat recovery boiler shown in Figure 1;
3 is an enlarged view of a waste heat recovery boiler according to a second embodiment of the present invention.
4 is an enlarged view of a waste heat recovery boiler according to a third embodiment of the present invention.

It should be noted that in this specification, when adding reference numerals to components of each drawing, the same components have the same number as possible, even if they are displayed on different drawings.

On the other hand, the meaning of the terms described in this specification should be understood as follows.

It should be understood that a singular expression includes a plurality of expressions unless the context clearly defines otherwise, and the terms "first", "second", etc. are intended to distinguish one component from another component, The scope of rights should not be limited by these terms.

It should be understood that terms such as “include” or “have” do not preclude the existence or addition possibility of one or more other features or numbers, steps, actions, components, parts 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 2 of the first item, the second item, or the third item, as well as each of the first item, the second item, and the third item. Any combination of items that can be presented from more than one dog.

The term "above" is meant to include not only the case where a configuration is formed on the top surface of another configuration, but also when a third configuration is interposed between these configurations.

Hereinafter, a waste heat recovery boiler according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, in describing the waste heat recovery boiler according to the embodiments of the present invention, the waste heat recovery boiler of the combined cycle power generation system will be described as an example.

The combined cycle power generation system is a gas generated during combustion of fuel, and the gas turbine is rotated to generate primary power. After the gas turbine is driven, the gas is discharged from the heat recovery steam generator using the gas discharged from the gas turbine. After generating, it is a system that generates secondary power by rotating the steam turbine with steam generated from a waste heat recovery boiler.

1 is a view showing the configuration of a combined cycle power generation system using a waste heat recovery boiler according to a first embodiment of the present invention.

As shown, the combined cycle power generation system according to the first embodiment of the present invention may include a gasification unit 110. The gasification unit 110 may generate raw synthetic gas, which is a combustible gas, by burning gaseous fuel, liquid fuel, or fossil fuel.

In particular, a system that generates power after generating syngas using coal as a fuel is called a coal gasification combined cycle power generation system. Coal may be introduced in the form of a slurry or pulverized coal. Coal in the slurry form is introduced with air or oxygen as the oxidizing agent, and steam is injected with oxidant air or oxygen as the coal.

Hereinafter, the description will be given by using pulverized coal as fossil fuel as an example.

In order to supply the pulverized coal to the gasification unit 110, a coal storage container 115 and a pulverizer 116 for pulverizing coal stored in the coal storage container 115 may be provided.

In addition, oxygen, which is an oxidizing agent, is generated in the air separator 120, and the air separator 120 may cool air to separate and generate oxygen and nitrogen. When air is cooled to a predetermined temperature, it is separated into liquid oxygen and liquid nitrogen due to the difference in boiling points between oxygen and nitrogen. Then, the low-temperature oxygen may be supplied to the gasification unit 110 after heat exchange.

Coal pulverized coal contains approximately 2 to 20% of coal ash as a non-combustible material.

Approximately 20% of the coal ash is melted by the high-temperature combustion heat of the gasification unit 110, and several particles become condensed slag, and a hopper (not shown) installed in communication with the lower portion of the gasification unit 110 together with water. It can be discharged through. Water discharged from the gasification unit 110 may be treated in the wastewater treatment unit 118, and water treated in the wastewater treatment unit 118 may be re-introduced into the gasification unit 110.

Then, the remaining approximately 80% of the coal ash is burned for each particle and scattered according to the flow of the raw synthesis gas, and the raw synthesis gas containing the coal ash can be purified while flowing through the purification device 130.

The raw syngas produced by the combustion of pulverized coal may include carbon dioxide, carbonyl sulfide (COS) and hydrogen sulfide, and may be purified in the purification device 130. Carbon dioxide, carbonyl sulfide (COS) and hydrogen sulfide are acid gases.

The purification device 130 may include a dust eliminator 131, a hydrolyzer 133, an acidic gas eliminator 135, and a sulfur eliminator 137.

The dust remover 131 may remove dust by separating dust containing fly ash contained in the raw synthesis gas and then collecting the dust. In addition, the dust eliminator 131 may be removed by separating the dust and then decompressing and cooling the dust. In addition, the dust remover 131 may also convert some of the carbonyl sulfide (COS) to hydrogen sulfide and carbon dioxide by hydrolysis.

The hydrocracker 133 may hydrolyze the synthetic gas from which the dust has been removed to remove the sulfur component, and the synthetic gas from which the sulfur component is removed from the hydrocracker 133 may be introduced into the wastewater treatment unit 118 for treatment. . At this time, the wastewater treatment unit 118 may transfer sour gas to the sulfur eliminator 137.

The acidic gas eliminator 135 may separate the synthetic gas from which the sulfur component has been removed into an acidic gas and pure synthetic gas, and may transport the acidic gas to the sulfuricizer 137. Then, the sulfur eliminator 137 separates and discharges sulfur and sulfuric acid, and can transport tail gas to a place of use.

The pure syngas separated from the acid gas eliminator 135 may be introduced into the combustor 140, and the compressor 150 may compress air and supply it to the combustor 140. Then, the combustor 140 may receive pure synthetic gas and compressed air to combust the pure synthetic gas and supply it to the gas turbine 160.

Thus, the gas turbine 160 may drive the generator while driving by the gas discharged from the combustor 140. And, after driving the gas turbine 160, the discharged gas may be used as a heat source to generate steam by flowing into the waste heat recovery boiler 200.

The steam generated in the waste heat recovery boiler 200 flows into the steam turbine 170 to drive the steam turbine 170, and generates electricity while another generator is driven by driving the steam turbine 170.

Embodiment 1

The waste heat recovery boiler 200 according to the first 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 illustrated in FIG. 1.

As shown, the waste heat recovery boiler 200 according to an embodiment of the present invention may include a body 210, and gas discharged from the gas turbine 160 on one side and the other side of the body 210 The inlet portion 211 and the outlet portion 213 provided with a chimney to be discharged may be respectively formed.

In the inside of the main body 210 on the inlet portion 211 side, the gas introduced into the inside of the main body 210 is uniformly moved to the discharge portion 213 side through the entire interior of the main body 210 to guide it so that it can be discharged. A distribution plate 221 may be installed, and a duct burner 225 for heating the gas to a higher temperature may be installed inside the main body 210 between the distribution plate 221 and the discharge portion 213.

Inside the main body 210 between the duct burner 225 and the discharge unit 213, an economizer 231 that heats water by heat of gas introduced into the main body 210 may be installed. , Inside the main body 210 between the duct burner 225 and the economizer 231, an evaporator 233 that vaporizes water delivered from the economizer 231 with heat of gas introduced into the main body 210 may be installed. In addition, a superheater 235 may be installed inside the body 210 between the duct burner 225 and the evaporator 233 to heat the steam delivered from the evaporator 233 to generate superheated steam.

The steam turbine 170 is driven by the superheated steam generated in the superheater 235 to generate electricity.

A water tank / deaerator 250 for removing oxygen dissolved in water may be installed at one side of the main body 210, and water of the water tank / deaerator 250 may be an economizer 231. ). In addition, water heated in the economizer 231 may be introduced into the evaporator 233 through the drum 237.

Based on the direction illustrated in FIG. 2, gas may be introduced to the left side of the main body 210 and discharged to the right side, and water may be introduced to the left side of the main body 210 and discharged to the left side.

In addition, the above-described economizer 231, evaporator 233, superheater 235, and drum 237 may be installed on the inner left side of the main body 210 adjacent to the inlet 211, which is the high pressure region 230, , The economizer 241, the evaporator 243, the superheater 245, and the drum 247 may be installed on the inner right side of the main body 210 adjacent to the discharge portion 213, which is the low pressure region 240, respectively.

Gas introduced into the main body 210 through the inlet portion 211 may contain nitrogen oxides that cause environmental pollution. Therefore, after removing the nitrogen oxide contained in the gas introduced into the body 210, the gas must be discharged to the discharge unit 213.

The waste heat recovery boiler 200 according to an embodiment of the present invention may use a selective catalytic reduction reactor 261 to remove nitrogen oxides contained in the gas. Since the optimum denitration efficiency occurs when the temperature of the gas is 300 to 400 ° C, the selective reduction catalyst reactor 261 is installed between the superheater 235 and the evaporator 233 where the gas temperature has a temperature range of 300 to 400 ° C. Can be.

The selective reduction catalyst reactor 261 uses a catalyst, and works with separately supplied ammonia to reduce nitrogen oxides contained in the gas into nitrogen and moisture. Ammonia is produced by hydrolyzing an aqueous solution of urea (수용액, Urea), and on one side of the main body 210, a hydrolysis machine 265 for generating ammonia by hydrolysis of an aqueous solution of urea may be installed. May include a chamber 265a into which the urea aqueous solution injected into the atomization state is injected from a spray nozzle or the like, and a burner 265b for heating the chamber 265a. In addition, a plurality of spray nozzles (not shown) for uniformly spraying the urea aqueous solution into the chamber 265a may be installed at the boundary between the chamber 265a and the burner 265b.

Thus, when fuel is introduced and burned with air into the burner 265b, the chamber 265a is heated, thereby hydrolyzing the atomized urea aqueous solution to produce ammonia.

The ammonia generated in the chamber 265a of the hydrolysis machine 265 can be supplied to the selective reduction catalyst reactor 261 and injected, so that ammonia can be injected uniformly into the selective reduction catalyst reactor 261. It can be injected into the selective reduction catalyst reactor 261 through the distribution plate 263 is formed of the injection hole.

The waste heat recovery boiler 200 according to the first embodiment of the present invention may supply a part of the gas flowing into the main body 210 to the hydrolysis unit 265 to heat the atomized urea aqueous solution. At this time, after being heated in the duct burner 225, a portion of the gas moving toward the superheater 235 may be supplied to the hydrolysis unit 2165. And, in order to supply the gas of the main body 210 between the duct burner 225 and the superheater 235 to the hydrolysis unit 265, the portion of the main body 210 between the duct burner 225 and the superheater 235 The hydrocracker 265 may be communicated by the gas supply line 215.

Then, the atomized urea aqueous solution of the chamber 265a of the hydrolyzator 265 is discharged from the gas turbine 170 and heated by the gas flowing into the main body 210, thereby reducing the fuel of the burner 265b. have.

In order for the aqueous solution of the urea in the chamber 265a to be hydrolyzed to ammonia, a predetermined residence time is required. If the temperature of the chamber 265a is low, a large residence time is required, so the volume of the chamber 456a must be increased. However, the waste heat recovery boiler 200 according to the first embodiment of the present invention can increase the temperature of the chamber 265a by using the high temperature gas of the main body 210. Therefore, the volume of the chamber 265a can be reduced.

When the temperature of the chamber 265a is greater than or equal to the set temperature, the aqueous urea solution can be oxidized to reduce the amount of ammonia produced. To this end, a first temperature sensor 271 that detects the temperature of the gas supply line 215 and transmits the control section 270 may be installed in the gas supply line 215, and the gas is controlled by the control section 270. Cooler 273 to cool the can be installed. At this time, the set temperature may be 630 ℃.

Example 2

As illustrated, the waste heat recovery boiler 300 according to another embodiment of the present invention has a second temperature sensor 375 that detects the temperature of the chamber 365a of the hydrolyzator 365 and transmits it to the control unit 370. It may be installed in the chamber (365a). In addition, the gas supply line 315 between the cooler 373 and the chamber 365a is controlled by the control unit 370 while controlling the opening and closing degree of the gas supply line 315 to adjust the hydrolysis unit 365. A valve 377 for adjusting the amount of gas supplied to may be installed.

Then, according to the temperature of the chamber 365a, since the amount of gas supplied to the hydrolyzator 365 can be adjusted, the fuel of the burner 365b can be further reduced.

Embodiment 3

4 is an enlarged view of a waste heat recovery boiler according to a third embodiment of the present invention, and only the difference from the first embodiment will be described.

As shown, the hydrolyzer 465 may include a chamber 465a into which an aqueous atomized urea solution is introduced and a burner 465b heating the chamber 465a.

Since ammonia is oxidized above about 630 ° C, in order to prevent oxidation of ammonia, the temperature of the chamber 465a must be lowered to a temperature at which ammonia is not oxidized. In addition, since the temperature at which the urea aqueous solution is optimally hydrolyzed in the chamber 465a may be 500 to 550 ° C, the atomized aqueous urea solution is injected into the chamber 465a maintaining 500 to 550 ° C, and the burner 465b When the chamber is heated with), the aqueous urea solution is hydrolyzed to produce ammonia.

Waste heat recovery boiler 400 according to the third embodiment of the present invention is a part of the gas flowing into the main body 410 is branched to the outside of the main body 410 to supply to the hydrolysis device 465 to atomize the atomized urea aqueous solution It can be used as a heat source for decomposition. Then, the fuel supplied to the burner 465b can be reduced compared to hydrolysis of the urea aqueous solution using only the burner 465b to generate ammonia.

The temperature of the gas supplied from the body 410 to the hydrolyzer 465 may be higher than the temperature at which the urea aqueous solution in the chamber 465a is hydrolyzed. However, in order to lower the temperature of the chamber 465a, introducing excess air into the chamber 465a may waste energy.

The waste heat recovery boiler 400 according to the third embodiment of the present invention heats the gas supply pipe 415 for supplying the gas of the main body 410 to the hydrolyzer 465 with steam discharged from the main body 410 The temperature of the gas supplied from the main body 410 to the hydrolyzer 465 may be lowered.

In addition, the steam having an increased temperature by exchanging heat with the gas supplied to the hydrocracker 465 exchanges heat with the combustion air required for combustion of the burner 465b to increase the temperature of the combustion air supplied to the burner 465b. have. Increasing the temperature of the combustion air required for combustion of the burner 465b can save the amount of fuel required for combustion of the burner 465b. More specifically, after heating in the duct burner 425, The gas moving toward the superheater 435 may be supplied to the hydrocracker 465. In order to supply the gas of the main body 410 between the duct burner 425 and the superheater 435 to the hydrolyzer 465, the site of the body 410 between the duct burner 425 and the superheater 435 and the hydrolyzer 465 may be communicated by the gas supply pipe 415. Then, the aqueous solution of the urea in the chamber 465a of the hydrolyzer 465 is discharged from the gas turbine 160 (see FIG. 1) and heated by the gas introduced into the main body 410, so that the fuel of the burner 465b is used. Can save.

 When the temperature of the gas supplied to the hydrolyzator 465 is greater than or equal to the set temperature, the aqueous urea solution may be oxidized and the amount of ammonia produced may decrease. To this end, the gas in the gas supply line 415 may be cooled and then supplied to the hydrolysis device 465.

The gas in the gas supply line 415 may be cooled using steam generated by the high pressure steam generating unit 430 or the low pressure steam generating unit 440 and discharged to the outside of the main body 410. 4 illustrates an example of cooling the gas in the gas supply line 415 by using the steam generated by the low pressure steam generator 440. That is, the steam discharge pipe 448 for discharging the steam generated in the low pressure steam generating unit 440 to the outside of the main body 410 is installed, and one side of the steam discharge pipe 448 is connected to the steam supply pipe 448a Is installed.

Since the steam in the steam supply line 448a is generated by exchanging heat with the gas in the main body 410 that is lower than the gas in the gas supply line 415, the temperature of the steam in the steam supply line 448a is that of the gas supply line 415. It is natural that the temperature is lower than the temperature of the gas.

Then, one side of the gas supply pipe 415 heat exchanges with one side of the steam supply pipe 448a. Then, since the temperature of the steam in the steam supply line 448a, which is lower than the gas in the gas supply line 415, rises, and the temperature of the gas in the gas supply line 415 decreases, the gas in the gas supply line 415 is It is cooled and supplied to the hydrolysis device 465.

An air supply line 476 may be installed in communication with the burner 465b, and the air supply line 476 may supply air as an oxidizing agent for burning fuel in the burner 465b. If the air can be preheated and supplied to the burner 465b, fuel as much as the fuel required to heat the air in the burner 465b can be saved.

To this end, one side of the air supply line 476 may exchange heat with the steam supply line 448a. More specifically, one side of the air supply line 476 may exchange heat with a portion of the steam supply line 448a that has been heat-exchanged with the gas supply line 415.

And, the part of the steam supply line 448a before heat exchange with the gas supply line 415 and the part of the steam supply line 448a heat-exchanged with the air supply line 476 communicate with each other by the steam supply line 448b. Can be. At this time, the portion of the steam supply pipe 448a and the steam supply branch pipe 448b prior to heat exchange with the gas supply pipe 415 are controlled by the control unit 470, and then to the steam supply pipe 448a and the steam supply branch pipe. A first valve 481a and a second valve 481b for adjusting the opening and closing degree of the 448b may be installed, respectively.

When the opening / closing degree of the steam supply line 448a and the steam supply branch line 448b is adjusted by using the first valve 481a and the second valve 481b, the gas supply line 415 supplied to the hydrolysis device 465 ) And the temperature of the air in the air supply line 476 supplied to the burner 465b. The control unit 470 may receive a signal from a sensor 483 sensing the temperature of the chamber 465b, and control the first valve 481a and the second valve 481b.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention pertains that various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention. It will be clear to those who have the knowledge of Therefore, the scope of the present invention is indicated by the following claims, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted to be included in the scope of the present invention.

200: waste heat recovery boiler
210: main body
265: hydrolysis
265a: chamber
265b: burner
270: control unit
271: first temperature sensor
273: cooler

Claims (9)

A main body on which an inlet portion through which gas is introduced and an outlet portion through which the gas is discharged are formed;
A steam generator installed on the body and generating steam;
A selective catalytic reduction reactor that is installed in the main body and removes nitrogen oxides contained in the gas introduced into the main body when ammonia is supplied;
A hydrolyzate for generating ammonia supplied to the selective reduction catalyst reactor while having a chamber into which an aqueous atomized urea solution is introduced and a burner to heat the chamber; And
It is provided between the inlet and the steam generator in the interior of the body and includes a duct burner for heating the gas flowing into the body and delivered to the steam generator to a higher temperature,
A waste heat recovery boiler, characterized in that a part of the gas heated by the duct burner after entering the main body is supplied to the hydrolyzate to hydrolyze the urea aqueous solution in the chamber. delete According to claim 1,
A gas supply pipe for supplying the gas of the main body to the hydrolysis unit is installed,
A first temperature sensor is installed in the gas supply line to sense the temperature of the gas supply line,
A waste heat recovery boiler, characterized in that a cooler is installed in the gas supply line to cool when the temperature of the gas is greater than or equal to the set temperature. According to claim 3,
A second temperature sensor for sensing the temperature of the chamber is installed in the chamber,
A waste heat recovery boiler, characterized in that a valve is installed in the gas supply line between the cooler and the chamber to control the amount of gas supplied to the hydrolyzator. According to claim 1,
The main body is provided with a gas supply pipe for supplying the gas of the main body to the hydrolysis unit,
The main body is provided with a steam discharge pipe for discharging the steam generated by the steam generator to the outside of the main body,
A steam supply line is installed in communication with one side of the steam discharge line,
A waste heat recovery boiler, characterized in that one side of the gas supply line is cooled by heat exchange with one side of the steam supply line. The method of claim 5,
A duct burner is installed inside the main body between the inlet and the steam generator,
The steam generating part includes a high pressure steam generating part installed inside the main body between the duct burner and the discharge part, and a low pressure steam generating part provided between the high pressure steam generating part and the discharge part,
The gas supply pipe communicates with a portion of the body between the duct burner and the high-pressure steam generating unit,
A waste heat recovery boiler, characterized in that the steam supply pipe supplies steam generated by the low pressure steam generator or the high pressure steam generator. The method of claim 6,
An air supply line is provided to supply air, which is an oxidant, to the burner,
One side of the air supply line is a waste heat recovery boiler, characterized in that heat exchange with the steam supply line. The method of claim 7,
The air supply pipe is a waste heat recovery boiler, characterized in that the heat exchange with the portion of the steam supply pipe heat exchanged with the gas supply pipe. The method of claim 8,
The portion of the steam supply pipe before heat exchange with the gas supply pipe and the portion of the steam supply pipe heat exchanged with the air supply pipe are mutually communicated by the steam supply branch pipe,
A sensor for sensing the temperature of the chamber is installed in the chamber,
Before the heat exchange with the gas supply line, a portion of the steam supply line and the steam supply branch line are provided with a first valve and a second valve, respectively, for controlling opening and closing degree of the gas supply line and the steam supply line. Waste heat recovery boiler, characterized by.

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