Flue gas treatment system and method in a combined cycle unit

Abstract

The present invention provides a flue gas treatment system and method in a combined cycle unit. The system includes: a gas turbine, a flue, a waste heat boiler, an ammonia-based reducing agent generating device, a heat exchanger, an atomizer, a first spraying device, a second spraying device, a first switching valve to a fourth switching valve, and a controller. The controller is configured to control the opening of the first switching valve and the second switching valve when the gas turbine starts, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue. During the operation of the gas turbine, the controller acquires the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and controls the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, so as to realize the treatment of the flue gas in the flue and / or the waste heat boiler. Thereby, the system improves the efficiency and effect of flue gas treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of combined cycle units, and particularly to a flue gas treatment system and method in a combined cycle unit. Background Art

[0002] During the power generation process of a combined cycle unit, the flue gas generated by the unit contains nitrogen oxides (NO x , such as NO and NO2, etc.). If NO x is directly discharged into the atmosphere, it will cause pollution. In recent years, with the improvement of national environmental protection standards, more stringent requirements have been put forward for the NOx emissions of gas turbine power plants in many regions.

[0003] In related technologies, the most common method is to use the catalytic reduction method (SCR, Selective Catalytic Reduction) to treat NO in the flue gas of a combined cycle unit. x Generally, an ammonia-based reducing agent is sprayed into the waste heat boiler. Under the action of a grid catalyst, the nitrogen oxides NO in the flue gas are x converted into nitrogen and water vapor (ammonia + NO x +(O2)→N2+H2O) and discharged into the atmosphere.

[0004] However, during the startup process of a combined cycle unit, when the gas turbine increases its load, the exhaust gas temperature is relatively low. The activity of the catalyst in the waste heat boiler is restricted by the flue gas temperature. Without sufficient preheating of the ammonia-based reducing agent, it is easy to cause the problem of reduced removal efficiency of NO in the flue gas. x Moreover, according to relevant literature research, during the process of treating NO in the flue gas of the waste heat boiler flue, it is difficult to ensure sufficient mixing of the sprayed ammonia-based reducing agent and the flue gas, which may cause the problem of reduced utilization rate of the ammonia-based reducing agent. x In view of the problems of reduced removal efficiency of NOx in the flue gas and reduced utilization rate of the ammonia-based reducing agent during the startup of the above-mentioned combined cycle unit, the present invention proposes a flue gas treatment system and method in a combined cycle unit.

[0005] Invention Content The present invention aims to solve the technical problems in related technologies to a certain extent.

[0006] To this end, the first object of the present invention is to propose a flue gas treatment system in a combined cycle unit, which improves the NOx removal efficiency and the utilization rate of the ammonia-based reducing agent for flue gas treatment.

[0007] The second object of the present invention is to propose a flue gas treatment method in a combined cycle unit.

[0008]

[0009] ​To achieve the above object, an embodiment of the first aspect of the present invention provides a system for treating flue gas in a combined cycle unit, including: a gas turbine, a flue, a waste heat boiler, an ammonia-based reducing agent generating device, a heat exchanger, an atomizer, a first spraying device, a second spraying device, a first switching valve to a fourth switching valve, and a controller; wherein, the gas turbine is connected to the waste heat boiler through the flue, an exhaust port of a compressor in the gas turbine and an exhaust port in the flue are sequentially connected to a first inlet of the atomizer through the first switching valve and the heat exchanger, the ammonia-based reducing agent generating device is connected to a second inlet of the atomizer through the second switching valve, an outlet of the atomizer is respectively connected to the first spraying device through the third switching valve, and is connected to the second spraying device through the fourth switching valve, the first spraying device is arranged in the flue, the second spraying device is arranged in the waste heat boiler, and the controller is respectively connected to the first switching valve to the fourth switching valve; wherein, the controller is configured to control the first switching valve and the second switching valve to open when the gas turbine starts, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue, and during the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and control the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, so as to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the treatment of the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to achieve the treatment of the flue gas in the waste heat boiler.

[0010] The flue gas treatment system in a combined cycle unit according to an embodiment of the present invention is composed of a gas turbine, a flue, a waste heat boiler, an ammonia-based reducing agent generating device, a heat exchanger, an atomizer, a first spraying device, a second spraying device, a first switching valve to a fourth switching valve, and a controller. The gas turbine is connected to the waste heat boiler through the flue. The exhaust port of the compressor in the gas turbine and an exhaust port in the flue are sequentially connected to the first inlet of the atomizer through the first switching valve and the heat exchanger. The ammonia-based reducing agent generating device is connected to the second inlet of the atomizer through the second switching valve. The outlet of the atomizer is respectively connected to the first spraying device through the third switching valve, and to the second spraying device through the fourth switching valve. The first spraying device is arranged in the flue, and the second spraying device is arranged in the waste heat boiler. The controller is respectively connected to the first switching valve to the fourth switching valve. Wherein, the controller is used to control the first switching valve and the second switching valve to open when the gas turbine starts, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheats the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue. And during the operation of the gas turbine, the controller obtains the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and controls the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, so as to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to realize the treatment of the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to realize the treatment of the flue gas in the waste heat boiler. Thus, the system improves the efficiency and effect of flue gas treatment.

[0011] In addition, the flue gas treatment system in the combined cycle unit proposed in the first aspect embodiment of the present invention may also have the following additional technical features:

[0012] According to an embodiment of the present invention, when the controller is used to control the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, it includes:

[0013] The controller is used to control the third switching valve to open when the temperature of the gas in the flue is within a preset temperature range, so as to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to realize the catalytic reduction treatment of the flue gas in the flue; and / or,

[0014] The controller is used to control the fourth switching valve to open when the temperature of the gas in the flue is within the preset temperature range, so as to spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to realize the catalytic reduction treatment of the flue gas in the waste heat boiler.

[0015] According to an embodiment of the present invention, the ammonia-based reducing agent generating device includes: an ammonia generating device, a hot water generating device, an ammonia pump, a hot water pump, and a mixer; wherein,

[0016] The ammonia generating device is connected to the first inlet of the mixer through the ammonia pump, the hot water generating device is connected to the second inlet of the mixer through the hot water pump, the outlet of the mixer is connected to the second switching valve, and the mixer is used to mix the ammonia and the hot water to generate the ammonia-based reducing agent.

[0017] According to an embodiment of the present invention, the ammonia generating device includes: a battery pack, brine, a synthesizer, and an ammonia storage tank; wherein, the battery pack is used to electrolyze the brine to generate nitrogen and hydrogen, thermally catalytically synthesize the nitrogen and the hydrogen through the synthesizer, and store the generated ammonia in the ammonia storage tank.

[0018] According to an embodiment of the present invention, the hot water generating device includes: a solar cell and a hot water storage tank; wherein, the solar power generation heats water and stores the heated hot water in the hot water storage tank.

[0019] According to an embodiment of the present invention, the system further includes: a steam turbine and a generator, wherein, the inlet of the steam turbine is connected to the waste heat boiler, the first outlet in the steam turbine is connected to the generator, and the generator is connected to the battery pack;

[0020] The steam turbine is used to convert the thermal energy of part of the steam in the waste heat boiler into the mechanical energy of the rotation of the rotor in the steam turbine to drive the generator to generate electricity;

[0021] The generator is used to charge part of the generated electric energy to the battery pack.

[0022] According to an embodiment of the present invention, the system further includes: a condenser and a circulating water pump group; wherein, the condenser is connected to the second outlet of the steam turbine, the first outlet of the condenser is connected to the waste heat boiler, and the second outlet and the third outlet of the condenser are sequentially connected to the hot water storage tank through the circulating water pump group and the heat exchanger;

[0023] The circulating water pump group is used to send part of the circulating water to the heat exchanger to be heat-exchanged through the heat exchanger, and then send the heated hot water to the hot water storage tank for storage through the hot water storage tank.

[0024] To achieve the above object, an embodiment of the second aspect of the present invention provides a method for treating flue gas in a combined cycle unit, including the following steps: When the gas turbine is started, control the first switching valve and the second switching valve to open, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue; During the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler; According to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, control the third switching valve and the fourth switching valve to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the treatment of the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to achieve the treatment of the flue gas in the waste heat boiler.

[0025] According to the method for treating flue gas in a combined cycle unit according to an embodiment of the present invention, when the gas turbine is started, control the first switching valve and the second switching valve to open, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue. During the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, control the third switching valve and the fourth switching valve to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the treatment of the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to achieve the treatment of the flue gas in the waste heat boiler. Thus, this method improves the efficiency and effect of flue gas treatment.

[0026] In addition, the method for treating flue gas in a combined cycle unit proposed in the embodiment of the second aspect of the present invention may further have the following additional technical features:

[0027] According to an embodiment of the present invention, the controlling the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler includes:

[0028] When the temperature of the gas in the flue is within a preset temperature range, control the third switching valve to open to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the catalytic reduction treatment of the flue gas in the flue; and / or

[0029] When the temperature of the gas in the flue is within the preset temperature range, control the fourth switching valve to open, so as to spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device, so as to realize the catalytic reduction treatment of the flue gas in the waste heat boiler.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0032] Figure 1 is a schematic diagram of a flue gas treatment system in a combined cycle unit according to an embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of a flue gas treatment system in a combined cycle unit according to an embodiment of the present invention;

[0034] Figure 3 is a flowchart of a flue gas treatment method in a combined cycle unit according to an embodiment of the present invention.

[0035] As Figure 1 shown:

[0036] 1. Gas turbine; 2. Compressor; 3. Flue; 4. Waste heat boiler; 5. Steam turbine; 6. Generator; 7. Condenser; 8. Circulating water pump, including two pumps 81 and 82; 9. Heat exchanger; 10. Hot water storage tank; 11. Ammonia storage tank; 12. Solar cell; 121. Ammonia pump; 122. Hot water pump; 131. First switching valve; 132. Second switching valve; 133. Third switching valve; 134. Fourth switching valve; 14. Atomizer; 151. First spraying device; 152. Second spraying device; 16. Mixer; 110. Ammonia-based reducing agent generating device; 111. Ammonia generating device; 112. Hot water generating device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0038] The following describes a flue gas treatment system and method in a combined cycle unit according to an embodiment of the present invention with reference to the accompanying drawings.

[0039] Figure 1It is a schematic diagram of a flue gas treatment system in a combined cycle unit according to an embodiment of the present invention.

[0040] As Figure 1 shown, Figure 1 the solid lines in it represent water / water vapor, and the dotted lines represent air / flue gas.

[0041] As Figure 1 shown, the flue gas treatment system in the combined cycle unit according to the embodiment of the present invention includes: a gas turbine 1, a flue 3, a waste heat boiler 4, an ammonia-based reducing agent generating device 110, a heat exchanger 9, an atomizer 14, a first spraying device 151, a second spraying device 152, a first switching valve 131 to a fourth switching valve 134, and a controller (not shown in the figure).

[0042] Among them, the gas turbine 1 is connected to the waste heat boiler 4 through the flue 3. The exhaust port of the compressor 2 in the gas turbine 1 and an exhaust port in the flue 3 are sequentially connected to the first inlet of the atomizer 14 through the first switching valve 131 and the heat exchanger 9. The ammonia-based reducing agent generating device 110 is connected to the second inlet of the atomizer 14 through the second switching valve 132. The outlet of the atomizer 14 is respectively connected to the first spraying device 151 through the third switching valve 133 and to the second spraying device 152 through the fourth switching valve 134. The first spraying device 151 is arranged in the flue 3, and the second spraying device 152 is arranged in the waste heat boiler 4. The controller is respectively connected to the first switching valve 131 to the fourth switching valve 134. The controller is used to control the opening of the first switching valve 131 and the second switching valve 132 when the gas turbine 1 starts, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device 110 enters the atomizer 14, and the ammonia-based reducing agent in the atomizer 14 is preheated by the high-temperature gas in the compressor 2 and the flue 3. And during the operation of the gas turbine 1, obtain the temperature of the gas in the flue 3 and the temperature of the gas in the waste heat boiler 4, and control the third switching valve 133 and the fourth switching valve 134 according to the temperature of the gas in the flue 3 and the temperature of the gas in the waste heat boiler 4, so as to spray the preheated ammonia-based reducing agent in the flue 3 through the first spraying device 151 to realize the treatment of the flue gas in the flue 3, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler 4 through the second spraying device 152 to realize the treatment of the flue gas in the waste heat boiler 4.

[0043] Among them, the ammonia-based reducing agent can be at least one of ammonia water and urea. In addition, since the reaction temperature for the optimal catalytic efficiency of the catalyst (for example, an iron-based or copper-based zeolite catalyst) is 315 - 480 °C, a preset temperature range interval of 315 - 480 °C can be set.

[0044] Among them, the catalysts include two types: metal oxides and zeolites. The optimal operating temperature range of the SCR device using metal oxide catalysts is 315°C to 400°C, while zeolite catalysts require an operating temperature of 315°C to 480°C, up to 600°C. Moreover, generally, the activation performance of SCR catalysts has a fault tolerance of ±40°C in the operating temperature range interval.

[0045] It should be noted that since it takes about 30 minutes for the waste heat boiler 4 to reach the set operating temperature when starting up, during the startup of the combined cycle unit, as the flue gas flow rate and temperature discharged from the gas turbine 1 rise rapidly, the gas turbine 1 remains at a relatively low load. If diffusion combustion control is mainly adopted, nitrogen oxides NO x emissions may increase.

[0046] In order to catalytically reduce nitrogen oxides NO x , and reduce the pollution of nitrogen oxides NO x to the air, when the combined cycle unit of the embodiment of the present invention starts up, the first switching valve 131 and the second switching valve 132 are controlled to open, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device 110 enters the atomizer 14, and the ammonia-based reducing agent in the atomizer 14 is preheated by the high-temperature gas in the compressor 2 and the flue 3. And, during the operation of the gas turbine 1, the temperature of the gas in the flue 3 is collected in real time by the temperature sensor arranged near the first spraying device 151, and the temperature of the gas in the waste heat boiler 4 is collected in real time by the temperature sensor arranged near the second spraying device 152. Then, the controller controls the third switching valve 133 and the fourth switching valve 134 according to the temperature of the gas in the flue 3 and the temperature of the gas in the waste heat boiler 4. Among them, when the temperature of the gas in the flue 3 is within the preset temperature range interval (280 - 450°C), the controller controls the third switching valve 133 to open, so as to spray the preheated ammonia-based reducing agent in the flue 3 through the first spraying device 151 to achieve catalytic reduction treatment of the flue gas in the flue 3; and / or, the controller is used to control the fourth switching valve 134 to open when the temperature of the gas in the flue 3 is within the preset temperature range interval (280 - 450°C), so as to spray the preheated ammonia-based reducing agent in the waste heat boiler 4 through the second spraying device 152 to achieve catalytic reduction treatment of the flue gas in the waste heat boiler 4.

[0047] Thus, the system preheats the ammonia-based reducing agent first when the gas turbine starts up by arranging the first spraying device in the flue, and then catalytically treats the nitrogen oxides NO x contained in the flue gas in the flue during the operation of the gas turbine, x which can greatly reduce the nitrogen oxides NO x in the flue gas entering the waste heat boiler, and greatly reduce the emission of nitrogen oxides NO into the air.The emissions are reduced, improving the efficiency and effectiveness of flue gas treatment.

[0048] Figure 2 It is a schematic diagram of a flue gas treatment system in a combined cycle unit according to an embodiment of the present invention.

[0049] As Figure 2 shown, the ammonia-based reducing agent generating device 110 includes: an ammonia generating device 111, a hot water generating device 112, an ammonia pump 121, a hot water pump 122, and a mixer 16; wherein, the ammonia generating device 111 is connected to the first inlet of the mixer 16 through the ammonia pump 121, the hot water generating device 112 is connected to the second inlet of the mixer 16 through the hot water pump 122, and the outlet of the mixer 16 is connected to the second switching valve 132. The mixer 16 is used to mix ammonia and hot water to generate an ammonia-based reducing agent.

[0050] As Figure 2 shown, the ammonia generating device 111 includes: a battery pack, brine, a synthesizer, and an ammonia storage tank 11; wherein, the battery pack is used to electrolyze brine to generate nitrogen and hydrogen, thermally catalytically synthesize the nitrogen and hydrogen through the synthesizer, and store the generated ammonia in the ammonia storage tank 11.

[0051] As Figure 2 shown, the hot water generating device 112 includes: a solar cell 12 and a hot water storage tank 10; wherein, solar power is used to heat water, and the heated water is stored in the hot water storage tank 10.

[0052] As Figure 2 shown, the above system further includes: a steam turbine 5 and a generator 6, wherein, the inlet of the steam turbine 5 is connected to the waste heat boiler 4, the first outlet in the steam turbine 5 is connected to the generator 6, and the generator 6 is connected to the battery pack; the steam turbine 5 is used to convert the thermal energy of part of the steam in the waste heat boiler 4 into the mechanical energy of the rotation of the rotor in the steam turbine 5 to drive the generator 6 to generate electricity; the generator 6 is used to charge part of the generated electric energy to the battery pack.

[0053] In this embodiment, the generator 6 supplies most of the generated electric energy to the power grid and a small part of the electric energy to charge the battery. Among them, the stage of using the electric energy of the generator 6 to charge the battery can be selected during the low electricity consumption period of each day.

[0054] As Figure 2As shown in the figure, the above system further includes: a condenser 7 and a group of circulating water pumps 8; among them, the condenser 7 is connected to the second outlet of the steam turbine 5, the first outlet of the condenser 7 is connected to the waste heat boiler 4, and the second outlet and the third outlet of the condenser 7 are sequentially connected to the hot water storage tank 10 through the group of circulating water pumps 8 and the heat exchanger 9; the condenser 7 is used to output part of the circulating water to the waste heat boiler 4, and send the other part of the circulating water to the heat exchanger 9 through the group of circulating water pumps 8, so that after heat exchange through the heat exchanger 9, the hot water obtained after heat exchange is sent to the hot water storage tank 10 for storage through the hot water storage tank 10.

[0055] In this embodiment, the group of circulating water pumps 8 may include a first water pump and a second water pump. Among them, one water pump can be used as the main water pump, and the other water pump can be used as the standby water pump. For example, when one water pump breaks down, the other water pump can be used; of course, one water pump or two water pumps can also be selectively controlled to start according to the amount of hot water required in the hot water pipe.

[0056] In order to filter and collect the flue gas and particulate matter in the flue gas entering the flue 3, a dust collector filter (not shown in the figure) can also be provided in the flue 3.

[0057] The following combines Figure 2 , to illustrate the process of treating flue gas using the flue gas treatment system of the combined cycle unit of the present invention, including the following situations:

[0058] During the startup process of the combined cycle unit, part of the compressed air is extracted from the compressor 2 of the gas turbine 1 and part of the gas is extracted from the flue 3, and they are sent to the heat exchanger 9 together to heat the circulating water discharged from the circulating water pump 8, and the heated water is sent to the hot water storage tank 10, so as to store the excess heat generated by the gas turbine 1 and avoid the heat overload of the heat exchange components in the waste heat boiler 4. In addition, part of the compressed air is extracted from the compressor 2 of the gas turbine 1 and part of the gas is extracted from the flue 3, and they are sent to the heat exchanger 9 together and then preheat the ammonia-based reducing agent in the atomizer 14. Thus, the heat generated by the gas turbine can be reasonably utilized and heat waste can be avoided.

[0059] During the normal operation of the combined cycle unit, gas can no longer be extracted from the flue 3, and only part of the air is extracted from the compressor 2 as the heat source of the heat exchanger 9. The hot water in the hot water storage tank 10 is pumped to the mixer 16 by the hot water pump 122 to be used for blending the ammonia-based reducing agent with the optimal reaction temperature, and then sent to the second spraying device 152 inside the waste heat boiler 4, and undergoes a catalytic reduction reaction with NOx in the flue gas in a suitable temperature range.

[0060] That is to say, the present invention introduces hot water energy storage. Due to the characteristic that the waste heat boiler 4 starts with a delay, the flue gas and circulating water flow rates required during the startup process of the unit are small. Therefore, a part of the circulating water can be led out by the circulating water pump group as energy storage water, and the excess flue gas generated by the gas turbine 1 is led to the heat exchanger 9 to heat the energy storage water, recovering the waste heat of the high-temperature flue gas and storing hot water, which is then used to heat the ammonia-based reducing agent after the combined cycle unit operates normally.

[0061] In summary, the flue gas treatment system in the combined cycle unit according to the embodiment of the present invention is composed of a gas turbine, a flue, a waste heat boiler, an ammonia-based reducing agent generating device, a heat exchanger, an atomizer, a first spraying device, a second spraying device, a first switching valve to a fourth switching valve, and a controller. The gas turbine is connected to the waste heat boiler through the flue. The exhaust port of the compressor in the gas turbine and an exhaust port in the flue are sequentially connected to the first inlet of the atomizer through the first switching valve and the heat exchanger. The ammonia-based reducing agent generating device is connected to the second inlet of the atomizer through the second switching valve. The outlet of the atomizer is respectively connected to the first spraying device through the third switching valve and to the second spraying device through the fourth switching valve. The first spraying device is arranged in the flue, and the second spraying device is arranged in the waste heat boiler. The controller is respectively connected to the first switching valve to the fourth switching valve; wherein, the controller is used to control the first switching valve and the second switching valve to open when the gas turbine starts, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue, and during the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and control the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, so as to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the treatment of the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to achieve the treatment of the flue gas in the waste heat boiler. Thus, the efficiency and effect of flue gas treatment are improved.

[0062] Figure 3 It is a flowchart of the flue gas treatment method in the combined cycle unit according to the embodiment of the present invention.

[0063] As Figure 3 shown, the flue gas treatment method in the combined cycle unit according to the embodiment of the present invention includes:

[0064] S1, when the gas turbine starts, control the first switching valve and the second switching valve to open, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue.

[0065] S2. During the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler.

[0066] S3. According to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, control the third switching valve and the fourth switching valve to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to treat the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to treat the flue gas in the waste heat boiler.

[0067] According to an embodiment of the present invention, controlling the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler includes:

[0068] When the temperature of the gas in the flue is within a preset temperature range, control the third switching valve to open to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to perform catalytic reduction treatment on the flue gas in the flue; and / or,

[0069] When the temperature of the gas in the flue is within a preset temperature range, control the fourth switching valve to open to spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to perform catalytic reduction treatment on the flue gas in the waste heat boiler.

[0070] It should be noted that for the details not disclosed in the method for treating flue gas in the combined cycle unit according to the embodiment of the present invention, please refer to the details disclosed in the flue gas treatment system in the combined cycle unit according to the embodiment of the present invention, and will not be elaborated here specifically.

[0071] According to the method for treating flue gas in the combined cycle unit according to the embodiment of the present invention, when the gas turbine starts, control the first switching valve and the second switching valve to open so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the compressor and the high-temperature gas in the flue. During the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, control the third switching valve and the fourth switching valve to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to treat the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to treat the flue gas in the waste heat boiler. Thus, the method improves the efficiency and effect of flue gas treatment.

[0072] The preliminary control value of the ammonia-based reducing agent is fixed. When the gas turbine flue gas flow rate changes with the fuel, atmospheric temperature, or burner performance, there is a problem of correcting the flow rate of the reducing agent. Due to the time delay caused by the catalytic reduction reaction during the purification of flue gas nitrogen oxides, the feedback value is delayed, and it often exhibits an excessive response characteristic. Especially when there is no normal range limit for the flow rate of the reducing agent, it is difficult to correctly control the flow rate of the reducing agent, and there is a problem of a longer flow rate stabilization time. Therefore, it is necessary to configure a correction value for the flow rate of the reducing agent for the flow control valve, and by pre-calculating the flow rate of the reducing agent required for purifying nitrogen oxides, the power adjustment of the flow valve is minimized to keep the system stable.

[0073] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0074] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0075] Any process or method description in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or more executable instructions for implementing a customized logic function or process. The scope of the preferred embodiments of the present invention includes additional implementations, where the functions can be executed in a manner that is not shown or discussed, including in a substantially simultaneous manner or in the reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

Claims

1. A flue gas treatment system in a combined cycle unit, characterized in that, Comprising: A gas turbine, a flue, a waste heat boiler, an ammonia-based reducing agent generating device, a heat exchanger, an atomizer, a first spraying device, a second spraying device, a first on-off valve to a fourth on-off valve, and a controller; wherein, the gas turbine is connected to the waste heat boiler through the flue, an exhaust port of a compressor in the gas turbine and an exhaust port in the flue are sequentially connected to a first inlet of the atomizer through the first on-off valve and the heat exchanger, the ammonia-based reducing agent generating device is connected to a second inlet of the atomizer through the second on-off valve, an outlet of the atomizer is respectively connected to the first spraying device through the third on-off valve, and to the second spraying device through the fourth on-off valve, the first spraying device is arranged in the flue, the second spraying device is arranged in the waste heat boiler, and the controller is respectively connected to the first on-off valve to the fourth on-off valve; wherein, The controller is configured to, when the gas turbine starts, control the first on-off valve and the second on-off valve to open, so that the ammonia-based reducing agent in the ammonia-based reducing agent generating device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the high-temperature gas in the compressor and the flue, and during the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, and control the third on-off valve and the fourth on-off valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, so as to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the treatment of the flue gas in the flue, and / or, spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to achieve the treatment of the flue gas in the waste heat boiler.

2. The system according to claim 1, wherein When the controller is configured to control the third on-off valve and the fourth on-off valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, it includes: The controller is configured to, when the temperature of the gas in the flue is within a preset temperature range, control the third on-off valve to open, so as to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to achieve the catalytic reduction treatment of the flue gas in the flue; and / or, The controller is configured to, when the temperature of the gas in the flue is within the preset temperature range, control the fourth on-off valve to open, so as to spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to achieve the catalytic reduction treatment of the flue gas in the waste heat boiler.

3. The system according to claim 1, characterized in that The ammonia-based reducing agent generating device includes: an ammonia generating device, a hot water generating device, an ammonia pump, a hot water pump, and a mixer; wherein, The ammonia generating device is connected to a first inlet of the mixer through the ammonia pump, the hot water generating device is connected to a second inlet of the mixer through the hot water pump, an outlet of the mixer is connected to the second on-off valve, and the mixer is used for mixing the ammonia and the hot water to generate the ammonia-based reducing agent.

4. The system according to claim 3, wherein The ammonia generation device includes: a battery pack, brine, a synthesizer, and an ammonia storage tank; wherein, the battery pack is used to electrolyze the brine to generate nitrogen and hydrogen, and generate ammonia through the ammonia synthesis process with the nitrogen and the hydrogen, and store it in the ammonia storage tank.

5. The system according to claim 3, wherein The hot water generation device includes: a solar cell and a hot water storage tank; wherein, the solar power generation heats water and stores the heated hot water in the hot water storage tank.

6. The system according to claim 1, wherein The system further includes: a steam turbine and a generator, wherein, an inlet of the steam turbine is connected to the waste heat boiler, a first outlet in the steam turbine is connected to the generator, and the generator is connected to the battery pack; The steam turbine is used to convert the thermal energy of part of the steam in the waste heat boiler into the mechanical energy of the rotation of the rotor in the steam turbine to drive the generator to generate electricity; The generator is used to charge part of the generated electric energy to the battery pack.

7. The system according to claim 6, characterized in that, The system further includes: a condenser and a circulating water pump group; wherein, the condenser is connected to a second outlet of the steam turbine, a first outlet of the condenser is connected to the waste heat boiler, and a second outlet and a third outlet of the condenser are sequentially connected to the hot water storage tank through the circulating water pump group and a heat exchanger; The circulating water pump group sends part of the circulating water through the circulating water pump group to the heat exchanger to exchange heat through the heat exchanger, and then sends the heated hot water to the hot water storage tank for storage through the hot water storage tank.

8. The system according to claim 1, wherein A dust collection filter is provided in the flue, and the dust collection filter is used to filter and collect the flue gas and particulate matter in the flue gas entering the flue.

9. A method for treating flue gas in a combined cycle unit, characterized in that, The method is implemented based on the flue gas treatment system in the combined cycle unit as described in any one of claims 1-8, and includes the following steps: When the gas turbine is started, control the first switching valve and the second switching valve to open, so that the ammonia-based reducing agent in the ammonia-based reducing agent generation device enters the atomizer, and preheat the ammonia-based reducing agent in the atomizer through the compressor and the high-temperature gas in the flue; During the operation of the gas turbine, obtain the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler; According to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler, control the third switching valve and the fourth switching valve to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to realize the treatment of the flue gas in the flue, and / or spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device to realize the treatment of the flue gas in the waste heat boiler.

10. The method according to claim 9, wherein The controlling the third switching valve and the fourth switching valve according to the temperature of the gas in the flue and the temperature of the gas in the waste heat boiler includes: When the temperature of the gas in the flue is within a preset temperature range, control the third switching valve to open to spray the preheated ammonia-based reducing agent in the flue through the first spraying device to realize the catalytic reduction treatment of the flue gas in the flue; and / or, When the temperature of the gas in the flue duct is within the preset temperature range, control the fourth switching valve to open, so as to spray the preheated ammonia-based reducing agent in the waste heat boiler through the second spraying device, so as to realize the catalytic reduction treatment of the flue gas in the waste heat boiler.

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