Denitration dilution air flue gas and air heat exchange system with bidirectional temperature adjustment function

Abstract

The utility model discloses a denitration dilution air flue gas air heat exchange system capable of adjusting temperature in two directions, which comprises a heat exchanger arranged in a boiler flue; the upstream end of the cold air main pipeline introduces cold primary air, and the downstream end communicates with the heat exchanger; the upstream end of the hot air main pipeline communicates with the heat exchanger, and dilution air flows out of the downstream end of the hot air main pipeline into the pyrolysis chamber or the ammonia-air mixer; the upstream end of the cooling pipeline communicates with the cold air main pipeline, the downstream end of the cooling pipeline communicates with the hot air main pipeline, and an electric adjusting butterfly valve and a non-return air door are arranged in the cooling pipeline; the upstream end of the heating pipeline is communicated with the hot air main pipeline, the downstream end of the heating pipeline is communicated with the cold air main pipeline, and an electric adjusting butterfly valve, a non-return air door and a high-temperature booster fan are arranged in the heating pipeline. Cold primary air circulates in the heat exchange system, and the temperature of dilution air can be reduced or increased by starting a cooling pipeline or a heating pipeline, so that the temperature of the dilution air required by denitration is flexibly adjusted, qualified denitration dilution air is provided, the denitration is normally put into operation, and the deep peak regulation and environmental protection requirements of a thermal power generating unit are met.

Description

Technical Field

[0001] The utility model relates to the field of denitration dilution wind for power station boilers, and more specifically, to a two-way temperature-adjustable denitration dilution wind flue gas-air heat exchange system. Background Art

[0002] At present, modern boilers, especially large power station boilers, mostly use SCR (selective catalytic reduction technology) to remove nitrogen oxides produced during boiler combustion to meet environmental protection requirements. Due to the safety issues of liquid ammonia, more and more power plants use urea hydrolysis or pyrolysis to produce ammonia, the reducing agent required by SCR. Whether it is hydrolysis or pyrolysis, dilution air is required to dilute ammonia and then spray it into the SCR inlet flue. Under the action of the catalyst, nitrogen oxides are reduced to nitrogen. Using the flue gas air heat exchanger arranged in the boiler to heat the cold primary air to the appropriate dilution air temperature is an economical method, and the cold primary air is clean and not easy to clog the ammonia dilution and injection pipelines.

[0003] As the requirements for atmospheric pollutant emissions from thermal power units have become increasingly stringent in recent years, thermal power units need to improve their deep peak-shaving capabilities. It is imperative for power station boilers to achieve grid connection and denitrification equipment to reach full load. Supercritical thermal power units also need to adapt to policy requirements and achieve deep peak-shaving capabilities.

[0004] Therefore, the heat exchanger must also adapt to the needs of deep peak regulation, and heat the cold primary air to a temperature that meets the needs as ammonia dilution air. However, when the power station boiler is running at high load, the flue gas volume is large. When the heat exchanger is arranged in the flue after the boiler tail shaft, the flue gas volume increases with the load. In order to prevent the heat exchanger from overheating, the flue gas damper of the front flue is closed and the flue gas damper of the rear flue is opened, so that the flue gas volume of the rear flue is further increased; when the power station boiler is running at low load, the flue gas volume is small. When the heat exchanger is arranged in the flue after the boiler tail shaft, the low-load flue gas volume decreases with the load. In order to increase the heat exchanger temperature, the flue gas damper of the front flue is opened and the flue gas damper of the rear flue is closed, so that the flue gas volume of the rear flue is further reduced. Since the size of the heating area cannot be changed after the heat exchanger is arranged, when the temperature of the full-load dilution air can be met and the heat exchanger and the dilution air hot air pipe material are not overheated, the outlet air temperature of the heat exchanger is often lower than the minimum air temperature requirement when the deep peak regulation is running at low load.

[0005] After searching, the flue gas heat exchanger modification system with publication number CN208186299U was found. When the boiler flue gas flow rate is small and the temperature is low, the system reheats the gas through an electric heater to reach the pyrolysis temperature, but this method has high cost and energy consumption, and does not fully utilize the flue gas heat. Therefore, this application proposes a two-way temperature-adjustable denitrification dilution air flue gas air heat exchange system to achieve full-load dilution air temperature to meet the denitrification system requirements, so that the denitrification can be put into normal operation and meet environmental protection requirements. Utility Model Content

[0006] One purpose of the utility model is to provide a two-way temperature-adjustable denitrification dilution air flue gas air heat exchange system. The cold primary air flows out after heat exchange in the heat exchanger. If the dilution air temperature is too high, the cooling pipeline is used to introduce cold air mixing; if the dilution air temperature is too low, the heating pipeline is used to recirculate the hot air at the heat exchanger outlet to the heat exchanger inlet, so as to flexibly adjust the dilution air temperature required for denitrification, provide qualified denitrification dilution air, enable the denitrification to be put into normal operation, and meet the deep peak regulation and environmental protection requirements of thermal power units.

[0007] In order to achieve these purposes and other advantages of the utility model, the utility model provides a two-way temperature-controlled denitrification dilution air flue gas air heat exchange system, including: a heat exchanger, which is arranged in the boiler flue; a cold air main line, whose upstream end introduces cold primary air and whose downstream end is connected to the heat exchanger; a hot air main line, whose upstream end is connected to the heat exchanger and whose downstream end flows out dilution air to the pyrolysis chamber or the ammonia-air mixer; a cooling pipeline, whose upstream end is connected to the cold air main line and whose downstream end is connected to the hot air main line, and a first electric regulating butterfly valve and a first check air door are provided in the cooling pipeline; a heating pipeline, whose upstream end is connected to the hot air main line and whose downstream end is connected to the cold air main line, and a second electric regulating butterfly valve, a second check air door and a high-temperature booster fan are provided in the heating pipeline.

[0008] Furthermore, two temperature-boosting pipeline butterfly valves are provided in the temperature-boosting pipeline, and the temperature-boosting pipeline butterfly valves are arranged on both sides of the second electric regulating butterfly valve. The two temperature-boosting pipeline butterfly valves and the second electric regulating butterfly valve are arranged on the air inlet side of the high-temperature booster fan.

[0009] Furthermore, an electric butterfly valve is provided in the heating pipeline, the electric butterfly valve is arranged on the air outlet side of the high-temperature booster fan, and the second check damper is arranged downstream of the heating pipeline away from the electric butterfly valve.

[0010] Furthermore, a second flow meter is provided in the temperature-increasing pipeline, and the second flow meter is provided between the electric butterfly valve and the temperature-increasing pipeline butterfly valve.

[0011] Furthermore, two cooling pipeline butterfly valves are provided in the cooling pipeline, the cooling pipeline butterfly valves are arranged on both sides of the first electric regulating butterfly valve, and the first check damper is arranged downstream of the cooling pipeline away from the cooling pipeline butterfly valves.

[0012] Furthermore, a first flow meter is provided in the cooling pipeline, and the first flow meter is provided between two butterfly valves of the cooling pipeline.

[0013] Furthermore, the connecting portion between the cooling pipeline and the main cold air pipeline is located upstream of the connecting portion between the heating pipeline and the main cold air pipeline.

[0014] Furthermore, the cold air main line is also provided with an air inlet butterfly valve, a third electric regulating butterfly valve and two cold air main line butterfly valves. The air inlet butterfly valve is arranged near the upstream end of the cold air main line, the third electric regulating butterfly valve is arranged upstream of the connecting part between the cooling pipeline and the cold air main line, the cold air main line butterfly valve is arranged on both sides of the third electric regulating butterfly valve, and a branch pipeline is also provided on the cold air main line. The upstream and downstream ends of the branch pipeline are connected to both sides of the two cold air main line butterfly valves, and a branch pipeline butterfly valve is provided on the branch pipeline.

[0015] Furthermore, a first temperature sensor and a third flow meter are provided at the upstream of the cold air main line, a second temperature sensor is provided at the downstream of the cold air main line, and a temperature display is provided at the downstream end of the cold air main line near the heat exchanger; a third temperature sensor and a third check air valve are provided at the downstream of the hot air main line, and the third check air valve is provided away from the temperature sensor and is arranged at the downstream end of the hot air main line.

[0016] Furthermore, pressure sensors are provided on the cold air main line and the hot air main line.

[0017] The utility model includes at least the following beneficial effects: cold primary air reaches the heat exchanger through the cold air main line, and the cold air is heated by the heat of the boiler flue gas through the heat exchanger and then exchanged out through the hot air main line. If the dilution air temperature is too high, the cooling pipeline is used to introduce cold air and mix it with the hot air after heat exchange to reduce the air temperature; if the dilution air temperature is too low, the heating pipeline is used to recirculate part of the hot air at the heat exchanger outlet to the heat exchanger inlet to increase the hot air temperature again. By activating the cooling pipeline or the heating pipeline, the dilution air temperature required for denitrification can be flexibly adjusted, and denitrification dilution air with qualified temperature can be provided to enable the normal operation of the denitrification process and meet the deep peak regulation and environmental protection requirements of the thermal power units.

[0018] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the denitrification dilution air flue gas air heat exchange system with two-way temperature regulation of the utility model. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0021] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0022] like Figure 1 As shown, the embodiment of the present application provides a two-way temperature-controlled denitrification dilution air flue gas air heat exchange system, including: a heat exchanger 3, which is arranged in the boiler flue, and the heat exchanger separates the flue gas in the boiler flue and the gas in the heat exchanger through a plate or a tube, so that the two fluids do not mix and only exchange heat. Optionally, a wall-type heat exchanger such as a tubular heat exchanger can be used; a cold air main line 1, whose upstream end introduces cold primary air, and optionally, a cold primary air fan or a dilution air fan can be used to introduce gas; the downstream end of the cold air main line 1 is connected to the air inlet of the heat exchanger 3; the hot air main line 2, whose upstream end is connected to the heat exchanger The air outlet of the heat exchanger 3 is connected, and the downstream end is connected to the pyrolysis chamber or the ammonia-air mixer, and the diluted air heated by the heat exchanger 3 flows out to the pyrolysis chamber or the ammonia-air mixer; the cooling pipeline 4, the upstream end of which is connected to the cold air main pipeline 1, and the downstream end is connected to the hot air main pipeline 2, and the cooling pipeline 4 is provided with a first electric regulating butterfly valve 401 and a first check damper 404; the heating pipeline 5, the upstream end of which is connected to the hot air main pipeline 2, and the downstream end is connected to the cold air main pipeline 1, and the heating pipeline 5 is provided with a second electric regulating butterfly valve 501, a second check damper 504 and a high-temperature booster fan 502.

[0023] After the heat exchanger 3 is installed in the boiler flue, all pipelines are connected. In the initial state, the first electric regulating butterfly valve 401 and the second electric regulating butterfly valve 501 are in the closed state. The cold primary air is introduced from the cold air main line 1 and flows into the heat exchanger 3. The high-temperature flue gas generated during boiler combustion flows into the boiler flue. The high-temperature flue gas increases the temperature of the gas flowing in the heat exchanger 3. The heated dilution air flows out through the hot air main line 2, and then the denitration process is carried out. When the SCR process is used to pyrolyze urea to produce ammonia for denitration, the dilution air pyrolyzes the urea in the pyrolysis chamber to produce ammonia. The produced ammonia reduces the nitrogen oxides produced during the boiler combustion process to meet environmental protection requirements. If the dilution air temperature is too low, the urea will not be completely thermally decomposed, forming crystalline sediments that will block the pipeline. If the dilution air temperature is too high, the produced ammonia will be easily decomposed, thus affecting the efficiency of ammonia production and denitrification. Therefore, it is usually necessary to maintain the dilution air temperature between 450℃ and 650℃. When using the SCR process to hydrolyze urea to produce ammonia and denitrify, the dilution air flows into the ammonia-air mixer, and it is usually necessary to maintain a dilution air temperature of 160℃ to 180℃ to dilute the concentration of the ammonia mixed gas after urea hydrolysis. If the boiler is working at a high load, the flow rate of high-temperature flue gas is large and the temperature is high, which leads to a high temperature of the dilution air flowing out of the hot air main line 2. The first electric regulating butterfly valve 401 in the cooling pipeline 4 is opened, and the opening of the first electric regulating butterfly valve 401 is adjusted so that the cold primary air passes through the cold air main line 1 and is diverted to the cooling pipeline 4. The diverted cold air passes through the cooling pipeline 4 and mixes with the hot air near the outlet of the heat exchanger 3 to reduce the hot air temperature. If the boiler is working at a low load, the flow rate of high-temperature flue gas is small and the temperature is low. , which results in a low dilution air temperature flowing out of the hot air main line 2, the second electric regulating butterfly valve 501 in the heating line 5 is opened, the opening of the second electric regulating butterfly valve 501 is adjusted, and the high-temperature booster fan 502 is turned on. The hot air flowing out of the heat exchanger 3 is diverted to the heating line 5 under the drive of the high-temperature booster fan 502. The diverted hot air flows back to the vicinity of the air inlet of the heat exchanger 3 through the heating line 5. As the cold primary air enters the heat exchanger 3, the hot air temperature is further increased to meet the dilution air temperature requirement. By activating the cooling line 4 or the heating line 5, the dilution air temperature can be lowered or increased, so that the dilution air temperature required for denitration can be flexibly adjusted under the full-load working scenario of the boiler, and the denitration dilution air with qualified temperature is provided to enable the normal operation of the denitration process.

[0024] In other embodiments, two heating pipeline butterfly valves 506 are further provided in the heating pipeline 5, and the two heating pipeline butterfly valves 506 are respectively arranged on both sides of the second electric regulating butterfly valve 501, wherein the second electric regulating butterfly valve 501 and the two heating pipeline butterfly valves 506 are both arranged on the air inlet side of the high-temperature booster fan 502. During the operation of the heat exchange system, the two heating pipeline butterfly valves 506 are in an open state. When the boiler is working at a low load, the flow rate and temperature of the high-temperature flue gas generated are small, which leads to a low dilution air temperature flowing out of the hot air main pipeline 2. Ensure that the first electric regulating butterfly valve 401 in the cooling pipeline 4 is in a closed state, open the second electric regulating butterfly valve 501 in the heating pipeline 5 and adjust the opening until the dilution air temperature flowing out meets the requirements, and when the second electric regulating butterfly valve 501 needs to be repaired, close the two heating pipeline butterfly valves 506. The provision of the two heating pipeline butterfly valves 506 facilitates the maintenance of the second electric regulating butterfly valve 501 and improves work efficiency.

[0025] In other embodiments, the heating pipeline 5 is further provided with an electric butterfly valve 503, which is arranged on the air outlet side of the high-temperature booster fan 502, and the second check damper 504 is arranged on the heating pipeline 5, far from the downstream of the electric butterfly valve 503. When the boiler is working at a low load, the flow rate and temperature of the high-temperature flue gas generated are small, which leads to a low temperature of the dilution air flowing out of the hot air main pipeline 2. Ensure that the first electric regulating butterfly valve 401 in the cooling pipeline 4 is in a closed state, open the electric butterfly valve 503 in the heating pipeline 5. and the high-temperature boost fan 502, and at the same time open the second electric regulating butterfly valve 501 and adjust the opening degree. When the heating pipeline 5 is in the open state, the electric butterfly valve 503 is opened. When the heating pipeline 5 stops working, the electric butterfly valve 503 and the second electric regulating butterfly valve 501 are closed. By arranging the electric butterfly valve 503 in the heating pipeline 5, the opening or closing of the heating pipeline 5 can be further controlled. The second check damper 504 is arranged at the downstream of the heating pipeline 5 to prevent cold air from flowing from the cold air main pipeline 1 into the heating pipeline 5.

[0026] In other embodiments, the heating pipeline 5 is further provided with a second flow meter 505, which is arranged between the electric butterfly valve 503 and any heating pipeline butterfly valve 506. When the boiler is working at a low load, the flow rate and temperature of the high-temperature flue gas generated are small and low, which leads to a low temperature of the dilution air flowing out of the hot air main pipeline 2. Ensure that the first electric regulating butterfly valve 401 in the cooling pipeline 4 is in a closed state, open the electric butterfly valve 503 and the high-temperature booster fan 502 in the heating pipeline 5, and open the second electric regulating butterfly valve 501 at the same time, and quantitatively adjust the opening of the second electric regulating butterfly valve 501 according to the hot air temperature and the indication of the second flow meter 505 until the dilution air temperature flowing out of the hot air main pipeline 2 meets the requirements. The setting of the second flow meter 505 can accurately adjust the flow rate of the gas in the heating pipeline 5, and after closing the two heating pipeline butterfly valves 506, the second flow meter 505 can be used to detect whether the second electric regulating butterfly valve 501 can be tightly closed.

[0027] In other embodiments, two cooling pipeline butterfly valves 403 are further provided in the cooling pipeline 4, the first electric regulating butterfly valve 401 is arranged in the middle of the cooling pipeline 4, the two cooling pipeline butterfly valves 403 are respectively arranged on both sides of the first electric regulating butterfly valve 401, and the first check damper 404 is arranged near the downstream of the cooling pipeline 4 far away from the cooling pipeline butterfly valve 403. When the boiler is working at a high load, the flow rate and temperature of the high-temperature flue gas generated are large, so that the temperature of the dilution air flowing out of the hot air main line 2 is high, the first electric regulating butterfly valve 401 in the cooling pipeline 4 is opened and the opening is adjusted, so that the cold primary air passes through the cold air main line 1 and is diverted to the cooling pipeline 4, and the diverted cold air passes through the cooling pipeline 4 and mixes with the hot air near the outlet of the heat exchanger 3 to reduce the hot air temperature. When the second electric regulating butterfly valve 501 needs to be repaired, the two cooling pipeline butterfly valves 403 are closed, and in other working states, the two cooling pipeline butterfly valves 403 are kept open. The cooling pipeline butterfly valves 403 are arranged on both sides of the first electric regulating butterfly valve 401 to facilitate maintenance, and the first check damper is arranged at the most downstream of the cooling pipeline 4 to prevent the diluted air from flowing back into the cooling pipeline 4.

[0028] In other embodiments, the cooling pipeline 4 is further provided with a first flow meter 402, which is arranged between two cooling pipeline butterfly valves 403. When the boiler is working at a high load, the flow rate and temperature of the high-temperature flue gas generated are large, which leads to a high temperature of the dilution air flowing out of the hot air main pipeline 2. The first electric regulating butterfly valve 401 in the cooling pipeline 4 is opened, and the opening of the first electric regulating butterfly valve 401 is adjusted according to the dilution air temperature flowing out of the hot air main pipeline 2 and the indication of the first flow meter 402, so that the cold primary air passes through the cold air main pipeline 1 and is diverted to the cooling pipeline 4. The diverted cold air passes through the cooling pipeline 4 and is mixed with the hot air near the outlet of the heat exchanger 3 to reduce the hot air temperature. By arranging the first flow meter 402 in the cooling pipeline 4, the flow rate of the gas in the heating pipeline 5 can be accurately adjusted, and the dilution air temperature can be adjusted.

[0029] In other embodiments, the connecting portion between the cooling pipeline 4 and the cold air main pipeline 1 is located upstream of the heating pipeline 5 and the cold air main pipeline 1. When the cooling pipeline 4 is turned on, the cold air flows into the cold air main pipeline 1 through the cooling pipeline 4, and a portion of the cold air is diverted to a place farther away from the heat exchanger 3 and flows into the hot air main pipeline 1. When the heating pipeline 5 is turned on, the hot air flows back through the heating pipeline 5 to a place closer to the heat exchanger 3 and then passes through the heat exchanger 3 for secondary heating. By arranging the cooling pipeline 4 and the heating pipeline 5 and the connecting portion of the cold air main pipeline 1 in front and back, it is avoided that when the cooling pipeline 4 is turned on, the cold air approaches the heat exchanger 3, resulting in an increase in the cold air temperature. When the heating pipeline 5 is turned on, the refluxed hot air approaches the heat exchanger 3, which reduces heat loss and improves the temperature control efficiency.

[0030] In other embodiments, the cold air main line 1 is further provided with an air inlet butterfly valve 101, a third electric regulating butterfly valve 107, two cold air main line butterfly valves 108 and a branch line 6. The air inlet butterfly valve 101 is arranged near the cold primary air inlet at the upstream end of the cold air main line 1, and the two cold air main line butterfly valves 108 are respectively arranged on both sides of the third electric regulating butterfly valve 107. The third electric regulating butterfly valve 107 and the two cold air main line butterfly valves 108 are all arranged upstream of the connecting part between the cooling pipeline 4 and the cold air main line 1, and the two cold air main line butterfly valves 108 and the third electric regulating butterfly valve 107 are all arranged between the two connecting parts of the branch line 6 and the cold air main line 1, and a branch line butterfly valve 601 is provided on the branch line 6. When the heat exchange system is working, the air inlet butterfly valve 101, the cold air main line butterfly valve 108 and the third electric regulating butterfly valve 107 are opened, and the branch pipeline butterfly valve 601 is closed. The cold primary air is introduced through the cold air main line 1, and flows out from the hot air main line 2 through the heat exchanger 3. During the operation of the heat exchange system, the air inlet butterfly valve 101 and the cold air main line butterfly valve 108 are in the open state. At the same time, the opening of the third electric regulating butterfly valve 107 can be adjusted according to the required dilution air temperature to control the flow rate of the cold primary air. When the third electric regulating butterfly valve 107 needs to be repaired online, the third electric regulating butterfly valve 107 and the cold air main line butterfly valve 108 are closed, and the branch pipeline butterfly valve 601 is opened. The cold primary air then passes through the upstream of the cold air main line 1 and the branch pipeline 6 to reach the downstream of the cold air main line 1 for subsequent heat exchange work. The setting of the air inlet butterfly valve 101 on the cold air main line 1 can open or close the operation of the entire heat exchange system. At the same time, adjusting the opening of the third electric regulating butterfly valve 107 can control the air intake of the cold primary air, and then control the air volume of the outflowing dilution air, so that the heat exchange can control the air volume of the dilution air while ensuring that the dilution air temperature meets the requirements. The setting of the branch pipeline 6 on the cold air main line 1 can ensure that the entire heat exchange system can continue to work when the third electric regulating butterfly valve 107 is online for maintenance, thereby saving time and improving the denitrification efficiency.

[0031] In other embodiments, a first temperature sensor 102 and a third flow meter 104 are further provided on the cold air main line 1 between the air inlet butterfly valve 101 and the connecting part between the branch line 6 and the upstream of the cold air main line 1, a second temperature sensor 105 is further provided downstream of the connecting part between the cold air main line 1 and the branch line 6, the second temperature sensor 105 is arranged between the connecting part between the cold air main line 1 and the branch line 6 and the cooling line 4, a temperature display 106 is further provided at the downstream end of the cold air main line 1 near the heat exchanger 3, the temperature display 106 is arranged downstream of the connecting part between the heating line 5 and the cold air main line 1, a third temperature sensor 201 and a third check air damper 203 are further provided downstream of the hot air main line 2, the third temperature sensor 201 is arranged downstream of the connecting part between the heating line 5 and the hot air main line 2, and the third check air damper 203 is arranged away from the temperature sensor near the air outlet near the downstream end of the hot air main line 2.

[0032] When the heat exchange system is working, each sensor and flow meter starts working at the same time. The cold primary air flows into the cold air main line 1 and passes through the first temperature sensor 102 and the third flow meter 104 to monitor the inflow temperature and flow of the cold primary air. After the cold primary air flows to the first electric regulating butterfly valve 401, the second temperature sensor 105 measures the temperature of the cold primary air in the pipeline again. After the cold primary air passes through the heat exchanger 3 for heat exchange, the hot air flows out through the hot air main line 2. The third temperature sensor 201 on the hot air main line 2 measures the hot air temperature to ensure that the hot air temperature is between the preset high temperature and the preset low temperature, wherein the preset high temperature and the preset low temperature are determined according to the dilution air temperature required for the subsequent denitrification work. If the boiler works at a high load, the flow rate and temperature of the high-temperature flue gas generated are large, which causes the third temperature sensor 201 to monitor the dilution air temperature higher than the preset high temperature. The first electric regulating butterfly valve 401 on the cooling pipeline 4 is opened and the opening is gradually increased until the third temperature sensor When the monitored temperature of the first electric regulating butterfly valve 401 is 10°C lower than the preset high temperature, stop adjusting the opening of the first electric regulating butterfly valve 401. If the load decreases during this period, causing the dilution air temperature to be lower than the preset high temperature by 20°C, reduce the opening of the first electric regulating butterfly valve 401 or close it until the dilution air temperature is lower than the preset high temperature by 10°C. If the boiler is working at a low load, the flow rate and temperature of the high-temperature flue gas generated are small, which causes the dilution air temperature flowing out of the hot air main line 2 to be lower than the preset low temperature, open the electric butterfly valve 503, the high-temperature booster fan 502 and the second electric regulating butterfly valve 501 in the heating pipeline 5, adjust the opening of the second electric regulating butterfly valve 501 and gradually increase the opening until the temperature monitored by the third temperature sensor 201 is higher than the preset low temperature by 10°C, stop adjusting the opening of the second electric regulating butterfly valve 501. If the load increases during this period, causing the dilution air temperature to be higher than the preset low temperature by 20°C, reduce the opening of the second electric regulating butterfly valve 501 or close it until the dilution air temperature is higher than the preset low temperature by 10°C. By arranging a plurality of sensors on the pipeline, the air volume and temperature of the dilution air flowing out of the hot air main pipeline 2 can be accurately controlled to improve efficiency.

[0033] In other embodiments, a first pressure sensor 103 is provided on the cold air main line 1, and a second pressure sensor 202 is provided on the hot air main line 2. The pressure values ​​fed back by the pressure sensors arranged on the cold air main line 1 and the hot air main line 2 are used to monitor and determine whether the heat exchanger 3 has a gas leakage. When the pressure difference between the pressure values ​​displayed by the first pressure sensor 103 on the cold air main line 1 and the second pressure sensor 202 on the hot air main line 2 exceeds 1000Pa, a comprehensive leakage check is performed on the heat exchanger 3 at the next shutdown. By arranging pressure sensors on the cold air main line 1 and the hot air main line 2, the leakage of the heat exchanger 3 is monitored, and the failure of the heat exchanger 3 is discovered and handled in time.

[0034] The number of equipment and processing scale described here are used to simplify the description of the utility model. The application, modification and variation of the two-way temperature-adjustable denitrification dilution air flue gas air heat exchange system of the utility model are obvious to those skilled in the art.

[0035] Although the implementation scheme of the utility model has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes. It can be fully applied to various fields suitable for the utility model. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A two-way temperature-adjustable denitrification dilution air flue gas air heat exchange system, characterized in that: include: A heat exchanger, which is arranged in the boiler flue; A cold air main line, the upstream end of which introduces cold primary air and the downstream end of which is connected to the heat exchanger; A hot air main line, the upstream end of which is connected to the heat exchanger, and the downstream end of which flows out dilution air to the pyrolysis chamber or the ammonia-air mixer; A cooling pipeline, the upstream end of which is connected to the cold air main pipeline, and the downstream end of which is connected to the hot air main pipeline, wherein a first electric regulating butterfly valve and a first check damper are provided in the cooling pipeline; The heating pipeline has an upstream end connected to the hot air main pipeline and a downstream end connected to the cold air main pipeline. The heating pipeline is provided with a second electric regulating butterfly valve, a second check damper and a high-temperature booster fan.

2. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: The heating pipeline is also provided with two heating pipeline butterfly valves, which are arranged on both sides of the second electric regulating butterfly valve. The two heating pipeline butterfly valves and the second electric regulating butterfly valve are arranged on the air inlet side of the high-temperature booster fan.

3. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: An electric butterfly valve is also provided in the heating pipeline, and the electric butterfly valve is arranged on the air outlet side of the high-temperature booster fan. The second check damper is arranged downstream of the heating pipeline away from the electric butterfly valve.

4. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 3, characterized in that: A second flow meter is also provided in the temperature-increasing pipeline, and the second flow meter is provided between the electric butterfly valve and the temperature-increasing pipeline butterfly valve.

5. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: The cooling pipeline is further provided with two cooling pipeline butterfly valves, the cooling pipeline butterfly valves are arranged on both sides of the first electric regulating butterfly valve, and the first check damper is arranged downstream of the cooling pipeline away from the cooling pipeline butterfly valves.

6. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: A first flow meter is also provided in the cooling pipeline, and the first flow meter is provided between two butterfly valves of the cooling pipeline.

7. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: The connecting portion between the temperature-lowering pipeline and the cold air main pipeline is located upstream of the connecting portion between the temperature-raising pipeline and the cold air main pipeline.

8. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: The cold air main line is also provided with an air inlet butterfly valve, a third electric regulating butterfly valve and two cold air main line butterfly valves. The air inlet butterfly valve is arranged near the upstream end of the cold air main line, the third electric regulating butterfly valve is arranged upstream of the connecting part between the cooling pipeline and the cold air main line, the cold air main line butterfly valve is arranged on both sides of the third electric regulating butterfly valve, and a branch pipeline is also provided on the cold air main line. The upstream end and downstream end of the branch pipeline are connected to both sides of the two cold air main line butterfly valves, and a branch pipeline butterfly valve is provided on the branch pipeline.

9. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: A first temperature sensor and a third flow meter are also provided at the upstream of the cold air main line, a second temperature sensor is also provided at the downstream of the cold air main line, and a temperature display is also provided at the downstream end of the cold air main line near the heat exchanger; a third temperature sensor and a third check air valve are also provided at the downstream of the hot air main line, and the third check air valve is arranged away from the temperature sensor and near the downstream end of the hot air main line.

10. The two-way temperature-adjustable denitration dilution air flue gas air heat exchange system according to claim 1, characterized in that: The cold air main line and the hot air main line are also provided with pressure sensors.

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