Condenser for ammonia power plant and flue gas waste heat utilization system

Abstract

The invention discloses a condenser and flue gas waste heat utilization system for an ammonia power plant, which belongs to the technical field of power generation and comprises a condenser, a condensate pump, a circulating water regulating valve, a liquid ammonia regulating valve, an ammonia regulating valve, a primary flue gas heat exchanger, a secondary flue gas heat exchanger, a water collector, a steam extraction heater, a pure ammonia burner, a boiler, an air pre-heater, a chimney and a steam turbine. A condenser and a liquid ammonia evaporator are integrally designed, the condenser comprises a liquid ammonia cooling area and a circulating water cooling area, liquid ammonia gasification cold energy of an ammonia power plant is used for cooling steam exhausted by a low-pressure cylinder of a steam turbine, the heat exchange efficiency is improved, and the load of a cooling tower is reduced; the tail of the pure ammonia boiler is free of dust removal and desulfurization facilities, waste heat of high-temperature and high-humidity flue gas at the outlet of the air pre-heater is used for replacing steam extraction of a steam turbine to heat condensed water and low-temperature ammonia gas, the generating power of a unit can be increased, secondary condensation of the ammonia gas can be prevented, the combustion stability of the ammonia gas can be improved, and meanwhile a large amount of water in the flue gas can be recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of power generation, and in particular relates to a condenser and a flue gas waste heat utilization system for an ammonia power plant. Background Art

[0002] New zero-carbon fuels such as green hydrogen and green ammonia have received more and more attention and research, and using them to replace pulverized coal combustion for power generation has become an important technical route for carbon emission reduction. Compared with green hydrogen, green ammonia has become the most important zero-carbon alternative fuel with its superior safety, low energy consumption, and high energy density. Storage and transportation advantages. Green ammonia can be synthesized by combining green hydrogen produced by renewable energy such as wind power and photovoltaics with air separation nitrogen production technology. Green ammonia is sent to the boiler for combustion and power generation. The goal of carbon neutrality in the power industry can be achieved by transforming existing coal-fired power units or building new ammonia power plants. Ammonia fuel is usually stored and transported in liquid form. Before being sent to the boiler for combustion, it needs to be gasified into ammonia gas in the plant to improve the combustibility of ammonia and also increase the calorific value of ammonia fuel.

[0003] At present, the main domestic thermal power units are pure condensing wet cooling units. The exhaust steam from the low-pressure cylinder of the steam turbine enters the condenser for condensation, which consumes a large amount of cooling circulating water. At the same time, a huge cooling tower needs to be built to dissipate the heat carried by the circulating water into the atmosphere to realize the thermal cycle of the unit. There is water loss in the process of heat exchange and cooling between the cooling tower and the air, and water needs to be replenished in time, consuming a large amount of water resources. Patented indirect air cooling system for ammonia-doped power plant and its control method (authorization number CN114320505 B) uses the cold energy of liquid ammonia vaporization to coordinate the cooling of the circulating water return water by the intercooler. This method uses indirect heat exchange to absorb the heat load of the condenser. First, there is a problem of low heat exchange efficiency. Second, the system is complex and the actual circulating water consumption has not been reduced.

[0004] Pure ammonia boilers generate electricity, and there is no smoke and sulfide emissions in the tail gas. The tail flue does not need to be designed with dust removal and desulfurization facilities. The flue gas temperature at the outlet of the boiler air preheater is usually around 120°C. Ammonia is rich in hydrogen, and a high concentration of water vapor is generated in the combustion flue gas. The high-temperature and high-humidity flue gas carries a large amount of waste heat and moisture that can be used. There is a patent for a flue gas waste heat utilization and water intake system for coal-fired boilers mixed with ammonia (authorization number CN 217209343 U). In the boiler ammonia combustion mode, a low-temperature ammonia heater is used to reduce the flue gas temperature, and then the liquid ammonia gasification cold energy is used to extract flue gas condensate water. However, when pure ammonia is burned, there is no dust removal and desulfurization equipment at the tail of the boiler, and the flue gas can use more waste heat, but the heat absorption of the low-temperature ammonia heater is limited, which is not enough to reduce the flue gas temperature below the dew point. A new waste heat utilization and water-saving system needs to be designed.

[0005] In view of the above-mentioned problems of ammonia power plants, new technologies need to be developed to solve the problems of large circulating water consumption of the units, large exhaust losses and high-concentration water loss in flue gas. Summary of the invention

[0006] The present invention provides a condenser and flue gas waste heat utilization system for an ammonia power plant. On the one hand, the system of the present invention integrates the condenser and the liquid ammonia evaporator into an integrated design, utilizes liquid ammonia to directly cool the turbine exhaust steam in the condenser, reduces the amount of circulating water in the condenser and the loss of water replenishment, reduces the investment in the cooling tower, and realizes the gasification of liquid ammonia, thereby improving the calorific value of the fuel entering the furnace; on the other hand, a heat exchanger is arranged in the flue at the rear of the boiler to utilize the waste heat of high-humidity flue gas to replace the turbine extraction steam to heat the condensate step by step, and heats the low-temperature ammonia at the outlet of the condenser at the same time, thereby achieving water and energy saving, reducing investment, and reducing the visual pollution of white smoke from the chimney.

[0007] To achieve the above object, the present invention adopts the following technical scheme: a condenser and flue gas waste heat utilization system for an ammonia power plant, comprising a condenser, a condensate pump, a circulating water regulating valve, a liquid ammonia regulating valve, an ammonia regulating valve, a primary flue gas heat exchanger, a secondary flue gas heat exchanger, a water collector, an extraction steam heater, a pure ammonia burner, a boiler, an air preheater, a chimney, and a steam turbine;

[0008] The upper part of the condenser is the low-pressure cylinder exhaust inlet, which is connected to the low-pressure cylinder outlet of the steam turbine; the lower part is the hot well, which is connected to the condensate pump inlet; the side is arranged from bottom to top in sequence: circulating water inlet, circulating water outlet, liquid ammonia inlet, ammonia outlet, the circulating water inlet is connected to the circulating water regulating valve, the circulating water outlet is connected to the cooling tower, the liquid ammonia inlet is connected to the liquid ammonia regulating valve, and the ammonia outlet is connected to the ammonia inlet of the secondary flue gas heat exchanger through the ammonia regulating valve;

[0009] A primary flue gas heat exchanger and a secondary flue gas heat exchanger are arranged at the tail of the boiler. The flue gas inlet of the primary flue gas heat exchanger is connected to the flue gas outlet of the air preheater, the flue gas inlet of the secondary flue gas heat exchanger is connected to the flue gas outlet of the primary flue gas heat exchanger, and the flue gas outlet of the secondary flue gas heat exchanger is connected to the chimney inlet; a water collector is arranged at the lower part of the secondary flue gas heat exchanger; the ammonia outlet of the secondary flue gas heat exchanger is connected to the pure ammonia burner;

[0010] The condensate pump outlet is connected to the condensate inlet of the secondary flue gas heat exchanger, the condensate outlet of the secondary flue gas heat exchanger is connected to the condensate inlet of the primary flue gas heat exchanger, the condensate outlet of the primary flue gas heat exchanger is connected to the inlet of the extraction steam heater, and the outlet of the extraction steam heater is connected to the boiler.

[0011] The present invention can produce the following beneficial effects:

[0012] The condenser adopts two-stage cooling to fully utilize the cold energy of liquid ammonia vaporization in the ammonia power plant to cool the turbine exhaust steam. This can achieve: (1) the condenser and liquid ammonia evaporator are designed as an integrated unit to improve heat exchange efficiency and reduce equipment investment; (2) the amount of circulating water is reduced, the investment in cooling towers and the power consumption of circulating water pumps are reduced, and the amount of circulating water makeup is reduced.

[0013] The primary flue gas heat exchanger and the secondary flue gas heat exchanger use the sensible heat and huge latent heat of the high-temperature and high-humidity flue gas to heat the condensate and low-temperature ammonia respectively, which can produce several benefits at the same time: (1) increase the ammonia inlet temperature, enhance combustion stability, increase boiler input heat, and reduce fuel consumption; (2) reduce the steam extraction volume of the turbine heat recovery system and increase the unit's power generation capacity; (3) realize the condensation and recovery of water in the high-humidity flue gas for reuse as the circulating water or raw water supplement source of the power plant; (4) reduce the flue gas humidity and reduce the visual pollution of the white smoke plume at the chimney outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG1 is a schematic diagram of a condenser and flue gas waste heat utilization system for an ammonia power plant according to the present invention;

[0015] Figure 2 is a schematic diagram of the internal structure of a condenser.

[0016] The accompanying drawings are marked as follows: 1 is a condenser, 2 is a condensate pump, 3 is a circulating water regulating valve, 4 is a liquid ammonia regulating valve, 5 is an ammonia regulating valve, 6 is a primary flue gas heat exchanger, 7 is a secondary flue gas heat exchanger, 8 is a water collector, 9 is an extraction heater, 10 is a pure ammonia burner, 11 is a boiler, 12 is an air preheater, 13 is a chimney, and 14 is a steam turbine; 1-1 is a low-pressure cylinder exhaust inlet, 1-2 is a hot well, 1-3 is a circulating water inlet, 1-4 is a circulating water outlet, liquid ammonia inlet 1-5, ammonia outlet 1-6, circulating water cooling area 1-7, liquid ammonia cooling area 1-8. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned purpose, the present invention adopts the following technical scheme.

[0018] The present invention proposes a condenser and flue gas waste heat utilization system for an ammonia power plant, as shown in FIG1 , wherein the system comprises a condenser 1, a condensate pump 2, a circulating water regulating valve 3, a liquid ammonia regulating valve 4, an ammonia regulating valve 5, a primary flue gas heat exchanger 6, a secondary flue gas heat exchanger 7, a water collector 8, an extraction steam heater 9, a pure ammonia burner 10, a boiler 11, an air preheater 12, a chimney 13, and a steam turbine 14.

[0019] The condenser 1 of the present invention comprises a low-pressure cylinder exhaust steam inlet 1-1, a hot well 1-2, a circulating water inlet 1-3, a circulating water outlet 1-4, a liquid ammonia inlet 1-5, an ammonia outlet 1-6, a circulating water cooling area 1-7, and a liquid ammonia cooling area 1-8.

[0020] The upper part of the condenser 1 is the low-pressure cylinder exhaust inlet 1-1, which is connected to the low-pressure cylinder outlet of the turbine 14; the lower part is the hot well 1-2 (condensate storage area), which is connected to the inlet of the condensate pump 2; the side is arranged from bottom to top in sequence: the circulating water inlet 1-3, the circulating water outlet 1-4, the liquid ammonia inlet 1-5, and the ammonia outlet 1-6. The circulating water inlet 1-3 is connected to the circulating water regulating valve 3, the circulating water outlet 1-4 is connected to the cooling tower, the liquid ammonia inlet 1-5 is connected to the liquid ammonia regulating valve 4, and the ammonia outlet 1-6 is connected to the ammonia inlet of the secondary flue gas heat exchanger 7 through the ammonia regulating valve 5.

[0021] Condenser 1 adopts a two-stage zoned cooling structure, using liquid ammonia and circulating water as cooling sources respectively. Liquid ammonia cooling zone 1-8 is located in the upper part of condenser 1, and circulating water cooling zone 1-7 is located in the lower part of condenser 1. The exhaust steam of low-pressure cylinder of turbine 14 first enters liquid ammonia cooling zone 1-8, and the exhaust steam waste heat quickly vaporizes the liquid ammonia. At the same time, part of the exhaust steam condenses into condensate and enters circulating water cooling zone 1-7. The circulating water continues to condense all the uncondensed exhaust steam in the condenser into condensate, and enters the hot well 1-2 (condensate storage area) at the bottom of condenser 1.

[0022] The liquid ammonia cooling zone 1-8 of the condenser 1 has phase changes in both the cold and hot fluids, so a plate heat exchanger structure is used to reduce the internal resistance of the heat exchanger. To prevent liquid ammonia corrosion and complex reaction with copper, the heat exchange plate is made of stainless steel or titanium plate, not copper plate.

[0023] The circulating water cooling zone 1-7 of the condenser 1 adopts a tubular heat exchanger structure, the tube side fluid is circulating water, the shell side fluid is uncondensed exhaust steam, and the heat exchange tubes are made of stainless steel, copper tubes or titanium tubes.

[0024] A primary flue gas heat exchanger 6 and a secondary flue gas heat exchanger 7 are arranged at the rear of the boiler 11, the flue gas inlet of the primary flue gas heat exchanger 6 is connected to the flue gas outlet of the air preheater 12, the flue gas inlet of the secondary flue gas heat exchanger 7 is connected to the flue gas outlet of the primary flue gas heat exchanger 6, and the flue gas outlet of the secondary flue gas heat exchanger 7 is connected to the inlet of the chimney 13; a water collector 8 is arranged at the lower part of the secondary flue gas heat exchanger 7; and the ammonia outlet of the secondary flue gas heat exchanger 7 is connected to the pure ammonia burner 10.

[0025] The outlet of the condensate pump 2 is connected to the condensate inlet of the secondary flue gas heat exchanger 7, the condensate outlet of the secondary flue gas heat exchanger 7 is connected to the condensate inlet of the primary flue gas heat exchanger 6, the condensate outlet of the primary flue gas heat exchanger 6 is connected to the inlet of the extraction heater 9, the outlet of the extraction heater 9 is connected to the boiler 11, the primary flue gas heat exchanger 6 is a gas-liquid heat exchange tube type, the heat exchange tube is a finned tube, made of CrMo alloy steel or stainless steel; the secondary flue gas heat exchanger 7 is a gas-gas and gas-liquid heat exchange tube type, the gas-gas heat exchange tube is a plain tube, the gas-liquid heat exchange tube is a finned tube, and the gas-gas heat exchange tube and the gas-liquid heat exchange tube are both thin-walled titanium tubes. The gas-gas and gas-liquid heat exchange tube bundles in the secondary flue gas heat exchanger 7 are arranged in zones or staggered.

[0026] The primary flue gas heat exchanger 6 and the secondary flue gas heat exchanger 7 are used to replace the steam extraction from the steam turbine to heat the condensed water step by step. The secondary flue gas heat exchanger 7 is also used to heat the low-temperature ammonia gas and recover the condensed water in the saturated flue gas.

[0027] The condensate first enters the secondary flue gas heat exchanger 7 through the condensate pump 2 to be heated by the latent heat of the saturated flue gas, and then enters the primary flue gas heat exchanger 6 to continue to be heated by the sensible heat of the high-temperature flue gas. The heated condensate enters the steam extraction heater 9, and finally enters the heating surface of the boiler 11 to absorb heat and evaporate to generate steam to drive the steam turbine 14 to do work.

[0028] The secondary flue gas heat exchanger 7 utilizes the latent heat of saturated flue gas to increase the temperature of ammonia to prevent secondary condensation of ammonia. After the ammonia is heated, it enters the boiler 11 to burn and generate electricity. The heat input to the boiler 11 increases, and the combustion stability is enhanced.

[0029] The operation control method of the condenser 1 of the present invention is:

[0030] Determine the amount of ammonia supplied according to the unit load;

[0031] The ammonia supply flow rate is adjusted by the liquid ammonia regulating valve 4;

[0032] Adjust the ammonia regulating valve 5 to maintain the ammonia outlet pressure between 0.7 MPa and 0.8 MPa;

[0033] The circulating water flow rate is adjusted by the circulating water regulating valve 3 to ensure that the vacuum degree and subcooling degree of the condenser 1 are within the design range.

[0034] The condenser 1 adopts two-stage cooling to fully utilize the cold energy of the liquid ammonia vaporization of the ammonia power plant to cool the exhaust steam of the steam turbine 14, which can achieve: (1) the condenser 1 and the liquid ammonia evaporator are designed as a whole to improve the heat exchange efficiency and reduce equipment investment; (2) the amount of circulating water is reduced, the investment in cooling towers and the power consumption of circulating water pumps are reduced, and the amount of circulating water makeup is reduced.

[0035] By calculating the cooling energy provided by the evaporation of liquid ammonia, the amount of circulating water reduced can be calculated: Taking a 300MW subcritical unit as an example (assuming a power generation efficiency of 37%, the corresponding standard coal consumption is about 332g / kWh), the ammonia consumption is 157t / h when running at full load. Usually, the pressure of the ammonia supply system of a power plant is 0.75MPa, and the saturation temperature of liquid ammonia under this pressure is 20℃. Assuming that the storage temperature of liquid ammonia is 15℃, the temperature of ammonia after vaporization is 25℃, the cooling energy of liquid ammonia vaporization is:

[0036] ;

[0037] In the formula, 1332.9 kJ / kg is the latent heat of vaporization of liquid ammonia, 4.609 kJ / (kg ℃) is the specific heat capacity of liquid ammonia, 2.105 kJ / (kg ℃) is the specific heat capacity of ammonia. Usually the inlet and return temperature difference of circulating water in a power plant is 10℃, so the amount of circulating water reduced by liquid ammonia as a cooling source is .

[0038] Calculated based on the general cooling water replenishment rate of 1.5%, the replenishment volume is reduced by 77 t / h, and the annual replenishment volume is reduced by 423,500 tons (based on the annual operating hours of the unit of 5,500), with obvious water-saving benefits.

[0039] The primary flue gas heat exchanger 6 and the secondary flue gas heat exchanger 7 utilize the sensible heat and huge latent heat of the high-temperature and high-humidity flue gas to heat the condensed water and low-temperature ammonia respectively, which can produce several benefits at the same time: (1) increase the ammonia inlet temperature, enhance combustion stability, increase the heat input to the boiler 11, and reduce fuel consumption; (2) reduce the steam extraction volume of the turbine 14 heat recovery system and increase the unit power generation capacity; (3) realize the condensation, recovery and reuse of water in the high-humidity flue gas, and use it as the circulating water or raw water supplementary water source of the power plant; (4) reduce the humidity of the flue gas and reduce the visual pollution of the white smoke plume at the chimney outlet.

[0040] Energy and water saving calculation of primary flue gas heat exchanger 6 and secondary flue gas heat exchanger 7: According to the ammonia combustion reaction equation 4NH3+2O2=2N2+6H2O, when the excess air coefficient of boiler 11 is 1.2, the volume fraction of each component of flue gas is 70% nitrogen, 27% water vapor, and 3% oxygen. According to the partial pressure of water vapor, the dew point of flue gas is 65℃. According to the operation data of 300MW subcritical unit, 8-stage extraction heat recovery system is designed for steam turbine 14, of which the steam parameters of the seventh and eighth stage extraction are 0.07MPa(a), 90℃; 0.027MPa(a), 67℃, and the heat released by extraction is 61GJ / h and 51GJ / h respectively. The flue gas temperature at the outlet of the air preheater 12 is considered to be 120°C. By comparing the flue gas temperature and the extraction parameters of the steam turbine 14, the following scheme is preferably adopted: the first-stage flue gas heat exchanger 6 uses the sensible heat of the high-temperature flue gas to replace the seventh-stage extraction steam to achieve preheating of the condensate. According to the calculation of the heat exchange of the seventh-stage extraction (assuming the heat exchange efficiency is 0.8), the flue gas temperature can be cooled to 69°C (close to the flue gas dew point of 65°C), while saving 27.4t / h of steam (seven extractions) to continue to work in the low-pressure cylinder of the steam turbine 14. The second-stage flue gas heat exchanger 7 uses the huge latent heat of water vapor carried by the 69°C nearly saturated flue gas to replace the eighth-stage extraction steam to continue heating the condensate, and can also preheat the low-temperature ammonia at the outlet of the condenser 1.

[0041] (1) Using flue gas waste heat to replace steam extraction from turbine 14 increases the generating capacity of the unit to:

[0042] ;

[0043] In the formula, 2641.2KJ / h and 2527.9 KJ / h are the enthalpy values ​​of the seventh-stage extraction and the eighth-stage extraction respectively, 2350.1KJ / h is the exhaust enthalpy value of the low-pressure cylinder, 0.9 is the efficiency in the low-pressure cylinder, and the standard coal saving is 981kg / h, and the annual standard coal saving is 5398 tons.

[0044] (2) Based on the calculation of the ammonia outlet temperature of the secondary flue gas heat exchanger 7 at 65°C (heat transfer end difference of 4°C) and the heat transfer efficiency of 0.8, the amount of flue gas condensate that can be recovered by the secondary flue gas heat exchanger 7 is 34.2 t / h, and the annual water saving is 188,000 tons.

[0045] (3) After the ammonia gas is heated, the heat input to boiler 11 is increased by 3.67MW, saving 452kg / h of standard coal, and the annual standard coal saving is 2,486 tons.

[0046] In total, the primary flue gas heat exchanger 6 and the secondary flue gas heat exchanger 7 save 7,884 tons of standard coal per year and 188,000 tons of water per year, with significant economic benefits.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A condenser and flue gas waste heat utilization system for an ammonia power plant, characterized in that: Including condenser, condensate pump, circulating water regulating valve, liquid ammonia regulating valve, ammonia regulating valve, primary flue gas heat exchanger, secondary flue gas heat exchanger, water collector, extraction heater, pure ammonia burner, boiler, air preheater, chimney, steam turbine; The upper part of the condenser is the low-pressure cylinder exhaust inlet, which is connected to the low-pressure cylinder outlet of the steam turbine; the lower part is the hot well, which is connected to the condensate pump inlet; The side is arranged from bottom to top in sequence with a circulating water inlet, a circulating water outlet, a liquid ammonia inlet, and an ammonia outlet. The circulating water inlet is connected to a circulating water regulating valve, the circulating water outlet is connected to a cooling tower, the liquid ammonia inlet is connected to a liquid ammonia regulating valve, and the ammonia outlet is connected to the ammonia inlet of the secondary flue gas heat exchanger through an ammonia regulating valve. A primary flue gas heat exchanger and a secondary flue gas heat exchanger are arranged at the tail of the boiler. The flue gas inlet of the primary flue gas heat exchanger is connected to the flue gas outlet of the air preheater, the flue gas inlet of the secondary flue gas heat exchanger is connected to the flue gas outlet of the primary flue gas heat exchanger, and the flue gas outlet of the secondary flue gas heat exchanger is connected to the chimney inlet; a water collector is arranged at the lower part of the secondary flue gas heat exchanger; the ammonia outlet of the secondary flue gas heat exchanger is connected to the pure ammonia burner; The condensate pump outlet is connected to the condensate inlet of the secondary flue gas heat exchanger, the condensate outlet of the secondary flue gas heat exchanger is connected to the condensate inlet of the primary flue gas heat exchanger, the condensate outlet of the primary flue gas heat exchanger is connected to the inlet of the extraction steam heater, and the outlet of the extraction steam heater is connected to the boiler.

2. A condenser and flue gas waste heat utilization system for an ammonia power plant according to claim 1, characterized in that: The condenser adopts a two-stage zoned cooling structure, using liquid ammonia and circulating water as cold sources respectively. The liquid ammonia cooling zone is located in the upper part of the condenser, and the circulating water cooling zone is located in the lower part of the condenser. The exhaust steam from the low-pressure cylinder of the turbine first enters the liquid ammonia cooling zone, and the waste heat of the exhaust steam quickly vaporizes the liquid ammonia. At the same time, part of the exhaust steam condenses into condensate and then enters the circulating water cooling zone. The circulating water continues to condense all the uncondensed exhaust steam in the condenser into condensate and enters the hot well at the bottom of the condenser.

3. The condenser and flue gas waste heat utilization system for an ammonia power plant according to claim 1, characterized in that: The condenser liquid ammonia cooling zone adopts a plate heat exchanger structure, and the heat exchange plates are made of stainless steel or titanium plates.

4. The condenser and flue gas waste heat utilization system for an ammonia power plant according to claim 1, characterized in that: The condenser circulating water cooling zone adopts a tubular heat exchanger structure. The tube side fluid is circulating water, the shell side fluid is uncondensed exhaust steam, and the heat exchange tubes are made of stainless steel, copper or titanium tubes.

5. The condenser and flue gas waste heat utilization system for an ammonia power plant according to claim 1, characterized in that: The primary flue gas heat exchanger is of gas-liquid heat exchange tube type, the heat exchange tube is a finned tube, and is made of CrMo alloy steel or stainless steel; the secondary flue gas heat exchanger is of gas-gas and gas-liquid heat exchange tube type, the gas-gas heat exchange tube is a plain tube, the gas-liquid heat exchange tube is a finned tube, and both the gas-gas heat exchange tube and the gas-liquid heat exchange tube are thin-walled titanium tubes. The gas-gas and gas-liquid heat exchange tube bundles in the secondary flue gas heat exchanger are arranged in zones or staggered.

6. The condenser and flue gas waste heat utilization system for an ammonia power plant according to claim 1, characterized in that: The operation control method of the condenser is: Determine the amount of ammonia supplied according to the unit load; The ammonia supply flow rate is adjusted by a liquid ammonia regulating valve; Adjust the ammonia regulating valve to maintain the ammonia outlet pressure between 0.7 MPa and 0.8 MPa; The circulating water flow rate is adjusted by the circulating water regulating valve to ensure that the condenser vacuum and subcooling are within the design range.

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