A heat recycling system of a flue gas water washing system of an ammonia desulfurization device

Abstract

The utility model discloses a kind of ammonia desulfurization device flue gas water washing system heat recycling system, including desulfurization tower, air blower room, gas-water heat exchanger, air preheater and boiler;The washing water outlet of desulfurization tower is communicated with the water inlet of water washing circulating tank by pipeline, the water outlet of water washing circulating tank is divided into two ways, one way is communicated with the hot medium import of gas-water heat exchanger by pipeline, another way is communicated with the import of water washing circulating pump by pipeline, the outlet of water washing circulating pump and the hot medium import of gas-water heat exchanger are all communicated with the washing water import of desulfurization tower by pipeline;The cold medium import of gas-water heat exchanger is communicated with atmosphere, the cold medium outlet of gas-water heat exchanger is communicated with the outdoor suction inlet of the inlet pipeline of air blower room by pipeline.The advantage is that: using the low-lying heat energy of desulfurization tower high-temperature washing water to heat boiler air blower inlet air, reduce steam consumption, reduce the energy consumption and operating cost of device, meet the industrial demand of energy saving and consumption reduction.

Description

Technical fields: This utility model relates to the field of ammonia desulfurization, specifically to a heat recovery system for a flue gas washing system in an ammonia desulfurization device. Background technology: For enterprises located in the extremely cold regions of northern my country, the extremely low winter temperatures significantly impact the safe operation of equipment. For example, during the process of air intake and combustion system injection by the blower of a thermal power boiler, the low air temperature at the blower inlet leads to severe scaling on the blower impeller, resulting in excessive blower vibration. Simultaneously, the air temperature at the boiler air preheater inlet is also too low. The large temperature difference between the hot and cold media during heat exchange in the air preheater exacerbates low-temperature corrosion, making leaks more likely and reducing its service life. To ensure the safe and stable operation of the blower, a heater is usually installed at the blower inlet to heat the air. However, this heater consumes a large amount of low-pressure steam, undoubtedly increasing energy consumption and operating costs, and significantly increasing the plant's energy consumption. Furthermore, the high temperature of the scrubbing water generated by the desulfurization unit's water washing system results in a large water load in the flue gas, leading to high production water consumption and high operating energy consumption. Increased flue gas humidity and longer exhaust plumes also negatively impact the company's environmental image. Utility model content: In order to solve the above problems, the purpose of this utility model is to provide a heat recovery system for the flue gas washing system of an ammonia desulfurization device.

[0004] This utility model is implemented by the following technical solution: A heat recovery system for flue gas scrubbing in an ammonia desulfurization unit includes a desulfurization tower, a blower chamber, a gas-water heat exchanger, an air preheater, and a boiler. The washing water outlet of the desulfurization tower is connected to the inlet of the water washing circulation tank via a pipeline. The outlet of the water washing circulation tank is divided into two paths: one path is connected to the heat medium inlet of the gas-water heat exchanger via a pipeline, and the other path is connected to the inlet of the water washing circulation pump via a pipeline. The outlet of the water washing circulation pump and the heat medium inlet of the gas-water heat exchanger are both connected to the washing water inlet of the desulfurization tower via pipelines. The cold medium inlet of the gas-water heat exchanger is open to the atmosphere, and the cold medium outlet of the gas-water heat exchanger is connected to the outdoor suction port of the blower's inlet pipe via a pipeline. The blower is located in the blower room, and the indoor suction port of the blower's inlet pipe is connected to the interior of the blower room. The air outlet of the blower is connected to the air inlet of the air preheater via a pipeline, and the air outlet of the air preheater is connected to the air inlet of the boiler via a pipeline.

[0005] Furthermore, the boiler exhaust gas is connected to the economizer flue gas inlet, the economizer flue gas outlet is connected to the air preheater flue gas inlet, the air preheater flue gas outlet is connected to the bag filter flue gas inlet, the bag filter flue gas outlet is connected to the desulfurization tower flue gas inlet, the desulfurization tower flue gas outlet is connected to the SCR device flue gas inlet, the SCR device flue gas outlet is connected to the wet electrostatic precipitator flue gas inlet, and the wet electrostatic precipitator flue gas outlet is connected to the chimney flue gas inlet.

[0006] Furthermore, a temperature sensor is installed at the inlet of the blower, and a first electric baffle valve is installed at the outdoor suction inlet of the inlet pipe. The signal output terminal of the temperature sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the first electric baffle valve.

[0007] Furthermore, a second electric damper valve is installed at the indoor suction inlet of the inlet pipe, and the signal output terminal of the controller is connected to the signal input terminal of the second electric damper valve.

[0008] Furthermore, a flow sensor is installed at the washing water outlet of the desulfurization tower, an inlet valve is installed at the inlet of the gas-water heat exchanger, an outlet valve is installed at the outlet of the gas-water heat exchanger, a drain outlet is opened at the bottom of the heat medium channel of the gas-water heat exchanger, and a drain valve is installed at the drain outlet; a steam vent is opened at the top of the heat medium channel of the gas-water heat exchanger, and a steam vent valve is installed at the steam vent. The signal output terminal of the flow sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminals of the inlet valve, the outlet valve, the drain valve, and the exhaust valve, respectively.

[0009] Furthermore, the outlet of the compressed air pipeline is connected to the heat medium channel of the gas-water heat exchanger via the pipeline, and a purge valve is provided at the outlet of the compressed air pipeline; a humidity sensor is provided at the exhaust port of the gas-water heat exchanger; the signal output terminal of the humidity sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the purge valve.

[0010] Furthermore, the gas-water heat exchanger is a tube-fin heat exchanger made of 316L stainless steel.

[0011] Advantages of this utility model: This invention utilizes the low-grade heat energy of the high-temperature scrubbing water from the desulfurization tower to heat the inlet air of the boiler blower, replacing the traditional low-pressure steam heating method of the air heater. This reduces steam consumption, lowers the energy consumption and operating costs of the device, and meets the industrial demand for energy conservation and emission reduction. By increasing the inlet air temperature of the blower, it avoids the problems of blower impeller scaling and vibration caused by low temperatures in winter, ensuring the stable operation of the blower. The increased air temperature entering the air preheater reduces the temperature difference within the air preheater, alleviates low-temperature corrosion, reduces the risk of leakage, and extends the service life of the air preheater. The desulfurization scrubbing water is returned to the desulfurization tower after being cooled by the gas-water heat exchanger, reducing the amount of water carried by the flue gas and reducing production water consumption. At the same time, the reduced flue gas humidity shortens the length of the exhaust plume, improving the company's environmental image. Attached image description: Figure 1 This is a schematic diagram of the system connection in this embodiment; Figure 2 This is the control principle diagram of this embodiment.

[0013] In the diagram: 1. Desulfurization tower; 2. Water washing circulation tank; 3. Water washing circulation pump; 4. Blower room; 5. Blower; 6. Gas-water heat exchanger; 7. Air preheater; 8. Boiler; 9. Economizer; 10. Bag filter; 11. Humidity sensor; 12. SCR device; 13. Wet electrostatic precipitator; 14. Chimney; 15. Temperature sensor; 16. First electric damper valve; 17. Controller; 18. Second electric damper valve; 19. Flow sensor; 20. Inlet valve; 21. Outlet valve; 22. Drain valve; 23. Exhaust valve; 24. Compressed air pipeline; 25. Purge valve. Detailed implementation method: The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] Example 1: like Figures 1 to 2 As shown, a heat recovery system for flue gas washing in an ammonia desulfurization unit includes a desulfurization tower 1, a blower chamber 4, a gas-water heat exchanger 6, an air preheater 7, and a boiler 8; the gas-water heat exchanger 6 is a tube-fin heat exchanger and is made of 316L stainless steel. The washing water outlet of desulfurization tower 1 is connected to the inlet of water washing circulation tank 2 through a pipeline. The outlet of water washing circulation tank 2 is divided into two paths. One path is connected to the heat medium inlet of gas-water heat exchanger 6 through a pipeline, and the other path is connected to the inlet of water washing circulation pump 3 through a pipeline. The outlet of water washing circulation pump 3 and the heat medium inlet of gas-water heat exchanger 6 are both connected to the washing water inlet of desulfurization tower 1 through pipelines. The cold medium inlet of the gas-water heat exchanger 6 is open to the atmosphere, and the cold medium outlet of the gas-water heat exchanger 6 is connected to the outdoor suction port of the inlet pipe of the blower 5 through a pipeline. The blower 5 is located inside the blower chamber 4, and the indoor suction port of the inlet pipe of the blower 5 is connected to the interior of the blower chamber 4. The air outlet of the blower 5 is connected to the air inlet of the air preheater 7 through a pipeline, and the air outlet of the air preheater 7 is connected to the air inlet of the boiler 8 through a pipeline.

[0016] The exhaust gas from boiler 8 is connected to the flue gas inlet of economizer 9. The flue gas outlet of economizer 9 is connected to the flue gas inlet of air preheater 7. The flue gas outlet of air preheater 7 is connected to the flue gas inlet of bag filter 10. The flue gas outlet of bag filter 10 is connected to the flue gas inlet of desulfurization tower 1. The flue gas outlet of desulfurization tower 1 is connected to the flue gas inlet of SCR device 12. The flue gas outlet of SCR device 12 is connected to the flue gas inlet of wet electrostatic precipitator 13. The flue gas outlet of wet electrostatic precipitator 13 is connected to the flue gas inlet of chimney 14.

[0017] In this embodiment, a temperature sensor 15 is installed at the inlet of the blower 5; a first electric baffle valve 16 is installed at the outdoor suction inlet of the inlet pipe; and a second electric baffle valve 18 is installed at the indoor suction inlet of the inlet pipe. A flow sensor 19 is installed at the washing water outlet of the desulfurization tower 1; an inlet valve 20 is installed at the inlet of the gas-water heat exchanger 6; an outlet valve 21 is installed at the outlet of the gas-water heat exchanger 6; a drain outlet is provided at the bottom of the heat medium channel of the gas-water heat exchanger 6, and the drain outlet is connected to the water collection tank; a drain valve 22 is provided at the drain outlet; a steam vent is provided at the top of the heat medium channel of the gas-water heat exchanger 6, and the steam vent is connected to the atmosphere; a steam vent valve 23 is provided at the steam vent; the outlet of the compressed air pipeline 24 is connected to the heat medium channel of the gas-water heat exchanger 6 through the pipeline; a purge valve 25 is provided at the outlet of the compressed air pipeline 24; and a humidity sensor 11 is provided at the steam vent of the gas-water heat exchanger 6. The signal output terminals of temperature sensor 15, flow sensor 19 and humidity sensor 11 are connected to the signal input terminals of controller 17. The signal output terminal of controller 17 is connected to the signal input terminals of first electric baffle valve 16, second electric baffle valve 18, inlet valve 20, outlet valve 21, drain valve 22, exhaust valve 23 and purge valve 25.

[0018] Job Description: Boiler flue gas (temperature typically 1200-1600℃, containing dust, SO2, NO) x Pollutants (such as heavy metals) first enter the economizer 9 located in the tail flue of boiler 8. The economizer uses the heat from the flue gas to heat the boiler 8 feedwater (heating the cold water to near saturation temperature), reducing the heat load on the boiler 8's evaporative heating surfaces and improving the boiler 8's thermal efficiency (by 5%-10%). Simultaneously, it lowers the flue gas temperature to 400-500℃. The flue gas then enters the air preheater 7 to further recover its heat and heat the cold air required for combustion (heating the air from room temperature to around 200℃), thereby increasing the furnace combustion temperature. At the same time, it lowers the flue gas temperature to 250-300℃, preventing damage to subsequent purification equipment due to high temperatures. Next, the flue gas enters the bag filter 10, where it is filtered through filter bags (such as those made of polyester or PTFE). Dust is trapped on the surface of the filter bags, preventing particulate matter emissions that pollute the atmosphere. After dust removal, the flue gas enters desulfurization tower 1, where limestone (CaCO3) slurry is sprayed into the tower to react with SO2 in the flue gas, producing calcium sulfite (CaSO3). This calcium sulfite is then oxidized into gypsum (CaSO4•2H2O) by air blown in by an oxidation fan, thus removing SO2 from the flue gas. The desulfurized flue gas then enters SCR unit 12 to remove nitrogen oxides (NO, NO2, etc.), reducing photochemical smog and acid rain. The denitrified flue gas then enters wet electrostatic precipitator 13, where an electric field adsorbs residual fine particulate matter (PM2.5). 2.5 This process removes droplets, heavy metals (such as Hg), and aerosols, further improving flue gas cleanliness (exit dust concentration can be reduced to 5 mg / m³). 3 (The following). The treated clean flue gas (temperature usually 50-80℃) enters the chimney 14 and is discharged into the atmosphere, reducing the concentration of ground pollutants through high-altitude diffusion.

[0019] Meanwhile, the high-temperature washing water discharged from desulfurization tower 1 first enters the water washing circulation tank 2 for temporary storage. The washing water from the water washing circulation tank 2 is output in two ways: one way is directly returned to desulfurization tower 1 after being pressurized by the water washing circulation pump 3 to maintain the main circulation of desulfurization washing; the other way is distributed according to a 160m... 3A portion of the high-temperature washing water is drawn out as a heat medium and introduced into the heat medium channel of the gas-water heat exchanger 6 at a flow rate of / h. This water exchanges heat with the outdoor air in the cold medium channel of the gas-water heat exchanger 6. After releasing heat, the high-temperature washing water cools down and flows back to the desulfurization tower 1 through the pipeline to continue participating in the washing process. The outdoor air absorbs heat and its temperature rises, entering the blower 5 through the outdoor intake. Simultaneously, the blower 5 draws in air from the blower chamber 4 through the indoor intake, mixing it with the outdoor air heated by the gas-water heat exchanger 6 in the inlet pipe. The controller 17 automatically adjusts the opening of the first electric damper valve 16 at the outdoor intake and the second electric damper valve 18 at the indoor intake based on the detection data from the temperature sensor 15 at the blower 5 inlet. By controlling the mixing ratio of the two types of air, the controller ensures that the air temperature entering the blower 5 remains stable at 7-13℃.

[0020] When the water washing system of desulfurization tower 1 malfunctions, the system automatically activates the protection mechanism, specifically: When the flow sensor 19 detects that the washing water drainage flow rate at the washing water outlet of the desulfurization tower 1 is less than the preset value, it determines that the water washing system of the desulfurization tower 1 has malfunctioned. The controller 17 adjusts the opening of the second electric damper valve 18 at the indoor intake to full open and closes the first electric damper valve 16 at the outdoor intake to ensure that the blower 5 only draws in air from the indoor environment, ensuring a stable gas supply to the combustion system. It also closes the inlet valve 20 and outlet valve 21 of the gas-water heat exchanger 6, and simultaneously opens the drain valve 22 and exhaust valve 23 of the heat medium channel of the gas-water heat exchanger 6, and opens the purge valve 25, introducing compressed air into the heat medium channel through the compressed air pipeline 24 to thoroughly purge residual washing water and prevent freezing and damage to the gas-water heat exchanger 6. When the humidity data detected by the humidity sensor 11 at the exhaust port is lower than the preset humidity value, it determines that the purging is complete, and closes the purge valve 25, drain valve 22, and exhaust valve 23.

[0021] In this embodiment, approximately 160m is drawn from desulfurization tower 1. 3 The / h washing water is used to heat the air drawn in from the external suction inlet of the blower chamber 4 of boiler 8. After heat exchange, the temperature of the washing water drops from 57℃ to 45℃, which effectively reduces the temperature of the flue gas washing water in desulfurization tower 1. This reduces the amount of water carried by the flue gas, lowers the production water consumption, optimizes and reduces the energy consumption of the unit, and at the same time reduces the humidity of the flue gas and controls the tailing of the flue gas, thus improving the company's environmental image.

[0022] Furthermore, the inlet air temperature of boiler 8 and blower 5 is heated using the heat from the desulfurization tower 1 water washing system as a heat source, resulting in a temperature of approximately 100,000 Nm³. 3The air temperature can be raised from -40°C in extremely cold environments to about 10°C, which can reduce the amount of low-pressure steam used for heating air in boiler 8 heaters by about 2.5t / h. If the heaters are used for 90 days a year and the cost of low-pressure steam is 45 yuan / t, then the annual cost of low-pressure steam consumption can be saved by about 243,000 yuan.

[0023] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A heat recycling system for a flue gas water washing system of an ammonia desulfurization device, characterized in that, This includes desulfurization towers, blower rooms, gas-water heat exchangers, air preheaters, and boilers; The washing water outlet of the desulfurization tower is connected to the inlet of the water washing circulation tank via a pipeline. The outlet of the water washing circulation tank is divided into two paths: one path is connected to the heat medium inlet of the gas-water heat exchanger via a pipeline, and the other path is connected to the inlet of the water washing circulation pump via a pipeline. The outlet of the water washing circulation pump and the heat medium inlet of the gas-water heat exchanger are both connected to the washing water inlet of the desulfurization tower via pipelines. The cold medium inlet of the gas-water heat exchanger is open to the atmosphere, and the cold medium outlet of the gas-water heat exchanger is connected to the outdoor suction port of the blower's inlet pipe via a pipeline. The blower is located in the blower room, and the indoor suction port of the blower's inlet pipe is connected to the interior of the blower room. The air outlet of the blower is connected to the air inlet of the air preheater via a pipeline, and the air outlet of the air preheater is connected to the air inlet of the boiler via a pipeline.

2. The heat recovery system of the flue gas water washing system of the ammonia desulfurization device according to claim 1, characterized in that, The boiler exhaust gas is connected to the economizer flue gas inlet; the economizer flue gas outlet is connected to the air preheater flue gas inlet; the air preheater flue gas outlet is connected to the bag filter flue gas inlet; the bag filter flue gas outlet is connected to the desulfurization tower flue gas inlet; the desulfurization tower flue gas outlet is connected to the SCR device flue gas inlet; the SCR device flue gas outlet is connected to the wet electrostatic precipitator flue gas inlet; and the wet electrostatic precipitator flue gas outlet is connected to the chimney flue gas inlet.

3. The heat recovery system of the flue gas water washing system of the ammonia desulfurization device according to claim 1, characterized in that, A temperature sensor is installed at the inlet of the blower, and a first electric baffle valve is installed at the outdoor suction inlet of the inlet pipe. The signal output terminal of the temperature sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the first electric baffle valve.

4. The heat recovery system of the flue gas washing system of an ammonia desulfurization unit according to claim 3, characterized in that, A second electric damper valve is installed at the indoor suction inlet of the inlet pipe, and the signal output terminal of the controller is connected to the signal input terminal of the second electric damper valve.

5. A heat recovery system for flue gas scrubbing in an ammonia desulfurization unit according to claim 4, characterized in that, A flow sensor is installed at the washing water outlet of the desulfurization tower, an inlet valve is installed at the inlet of the gas-water heat exchanger, an outlet valve is installed at the outlet of the gas-water heat exchanger, a drain outlet is opened at the bottom of the heat medium channel of the gas-water heat exchanger, and a drain valve is installed at the drain outlet; a steam vent is opened at the top of the heat medium channel of the gas-water heat exchanger, and a steam vent valve is installed at the steam vent. The signal output terminal of the flow sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminals of the inlet valve, the outlet valve, the drain valve, and the exhaust valve, respectively.

6. The heat recovery system of the flue gas washing system of an ammonia desulfurization unit according to claim 5, characterized in that, The outlet of the compressed air pipeline is connected to the heat medium channel of the gas-water heat exchanger through the pipeline, and a purge valve is provided at the outlet of the compressed air pipeline; a humidity sensor is provided at the exhaust port of the gas-water heat exchanger; the signal output terminal of the humidity sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the purge valve.

7. A heat recovery system for flue gas scrubbing in an ammonia desulfurization unit according to any one of claims 1-6, characterized in that, The gas-water heat exchanger is a tube-fin heat exchanger made of 316L stainless steel.

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