Air preheater anti-blocking regulation method based on one-side temperature rising pyrolysis

Abstract

A kind of air preheater anti-blocking regulation method based on unilateral temperature rising pyrolysis.Sometimes, air preheater will appear the problem of blocking, which not only affects its normal operation, but also can cause threat to the safety and economy of power plant. The present application comprises the following steps: closing #4 air preheater side #10, #11, #12 smoke cooler water inlet electric door one by one;In situ, gradually closing #3 air preheater outlet hot secondary air damper from 1 to 0%, when 700MW load, #3 air preheater outlet flue gas temperature should be raised to 160℃;Gradually closing #3 air preheater outlet hot secondary air damper 2, more than 50% opening degree according to 10% / time, less than 50% opening degree according to 5% / time, close to 20%;When 700MW load, #3 air preheater outlet flue gas temperature rises to 185℃. The present application is used for unilateral air preheater temperature rising to cure blocking.

Description

Technical Field

[0001] This invention relates to a method for preventing blockage in an air preheater based on unilateral heating pyrolysis. Background Technology

[0002] Air preheaters, as indispensable auxiliary equipment in thermal power plant boilers, have the core function of preheating the air required for boiler combustion using high-temperature flue gas. This process is achieved through continuously rotating heat exchange fins, which slowly carry heat transfer elements through the low-temperature region of the flue gas, thereby facilitating heat exchange between the hot flue gas and the cold air. This mechanism not only recovers heat from the flue gas and reduces the exhaust gas temperature, thus improving boiler efficiency, but also aids in fuel ignition and combustion, reducing heat loss due to incomplete combustion. However, air preheaters can sometimes experience blockages, which not only affect their normal operation but may also threaten the safety and economic efficiency of the power plant. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preventing and controlling air preheater blockage based on unilateral heating pyrolysis, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preventing and controlling air preheater blockage based on unilateral heating pyrolysis, comprising the following steps: (1) Close the electric water inlet valves of flue gas coolers #10, #11, and #12 on the side of air preheater #4 one by one; (2) Gradually close the hot secondary air damper at the outlet of the #3 air preheater from 1% to 0% on-site. At a load of 700MW, the flue gas temperature at the outlet of the #3 air preheater should rise to 160℃. (3) Gradually reduce the opening of the hot secondary air damper 2 at the outlet of the #3 air preheater. If the opening is above 50%, reduce it by 10% per cycle, and if the opening is below 50%, reduce it by 5% per cycle, until it is reduced to 20%. (4) When the outlet flue gas temperature of the #3 air preheater rises to 185°C at a load of 700MW, if the outlet flue gas temperature does not reach 180°C, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero on site. (5) During operation, increase the output of the #4 primary air fan and the #4 blower heater, and raise the inlet air temperature of the #4 air preheater to about 40°C to prevent the #4 air preheater current from fluctuating. (6) During the process of increasing the outlet flue gas temperature of the #3 air preheater, strengthen the on-site inspection of the air preheater and flue gas cooler, check for any abnormal jamming or grinding sounds, and continue to raise the temperature only after the air preheater current is stable. Control it to not exceed 15A. Otherwise, stop the operation and check on-site whether there is any smoke coming out of the induced draft fan expansion joint. (7) When the flue gas temperature of the #3 air preheater rises to 150℃, it should be kept stable for 10 minutes. Then, the flue gas temperature should be increased to 160℃ and kept stable for 10 minutes. Next, the flue gas temperature should be increased to 170℃ and kept stable for 10 minutes. Finally, the flue gas temperature should be increased to 185℃ and kept stable for 4-6 hours. During the stabilization period, the operation of the boiler and desulfurization system should be thoroughly checked. (8) If the flue gas temperature of the #3 air preheater rises too quickly or rises to >200℃, or if the load decreases and the flue gas temperature at the outlet of the #4 air preheater is lower than 90℃, adjust by opening the hot secondary air dampers 2 and 1 at the outlet of the #3 air preheater. (9) After the pyrolysis is completed, open the hot secondary air dampers 2 and 1 at the outlet of the #3 air preheater in sequence. During the recovery process, the rate of change of the flue gas temperature at the outlet of the air preheater should still be controlled to be ≤1℃ / min. (10) Maintain the outlet flue gas temperature of the #3 air preheater between 180℃ and 195℃, closely monitor the air preheater current fluctuations to not exceed 15A, the temperature of the upper and lower bearings of the air preheater <70℃, the temperature of the blower motor and blower bearings <80℃, and the vibration of any blower or blower bearing <4mm / s. (11) When increasing the outlet flue gas temperature of the #3 air preheater, if the outlet header water temperature of the #7, #8, and #9 flue gas coolers is close to the saturation temperature under the corresponding pressure, the inlet water pressure of the flue gas coolers should be increased to 1.5 MPa. If there is still vibration, close the manual inlet and outlet water valves of the heat exchanger group on the spot, and open the drain valve of the heat exchanger group to drain the water in the heat exchanger group to avoid water hammer.

[0005] (12) After the test begins, closely monitor the flue gas temperature at the inlet of the desulfurization absorption tower and the flue gas temperature at the outlet. When the flue gas temperature at the inlet of the absorption tower is greater than 160°C, immediately start the emergency spray cooling. If the temperature continues to rise and the flue gas temperature at the outlet is greater than 65°C, immediately stop the operation.

[0006] The air preheater anti-blocking control method based on unilateral heating pyrolysis, the specific process of step (1) is as follows: close the electric water inlet valves of flue gas coolers #10, #11 and #12 on the side of air preheater #4 one by one, and confirm that they are all closed on the spot; control the outlet flue gas temperature of flue gas coolers #7, #8 and #9 to be no lower than 130℃ and no higher than 150℃, and control the outlet flue gas temperature of flue gas coolers #10, #11 and #12 to be no lower than 90℃.

[0007] The method for preventing blockage of an air preheater based on unilateral heating pyrolysis is described in step (2), in which the hot secondary air damper at the outlet of the #3 air preheater is gradually closed from 1% to 0%, with an opening of more than 50% at 15% per cycle and an opening of less than 40% at 5% per cycle.

[0008] The air preheater anti-blocking control method based on unilateral heating pyrolysis is described above. The specific process of step (3) is as follows: gradually reduce the opening of the hot secondary air damper 2 at the outlet of the #3 air preheater. When the opening is above 50%, reduce it by 10% per cycle, and when the opening is below 50%, reduce it by 5% per cycle. Reduce it to 20%, and increase the flue gas temperature at the outlet of the #4 air preheater at a rate not greater than 1℃ / min to prevent the air preheater from jamming or tripping due to uneven expansion. If the load increases, the hot secondary air damper 2 at the outlet of the #3 air preheater should be opened larger. Strictly control the outlet pressure of the blower to not exceed 4.0kPa.

[0009] The air preheater anti-clogging control method based on unilateral heating pyrolysis, the specific process of step (4) is as follows: When the outlet flue gas temperature of the #3 air preheater rises to 185℃ at a load of 700MW, if the outlet flue gas temperature does not reach 180℃ or above, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero on-site (10% / time for opening above 50%, 5% / time for opening below 50%). According to the rise of the outlet flue gas temperature of the #4 air preheater, the #3 denitrification inlet flue gas damper 2 is closed, not less than 50%, to maintain the stability of the total air volume, oxygen content, and negative pressure in the furnace. After this step, the rise of the exhaust gas temperature and the fluctuation of the air preheater current are observed. During the heating process, the air preheater is blown with soot to warm the tubes. When the temperature rises to 170℃, the cold and hot ends of the #3 air preheater are continuously blown with soot. Beneficial effects

[0010] 1. Under 700MW load, the outlet flue gas temperature of the #3 air preheater rises to 185℃. If the outlet flue gas temperature does not reach 180℃ or higher, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero (10% opening per cycle for openings above 50%, and 5% opening per cycle for openings below 50%). Based on the rise in the outlet flue gas temperature of the #4 air preheater, the #3 denitrification inlet flue gas damper 2 is closed to a minimum of 50%, maintaining stable total furnace airflow, oxygen content, and negative pressure. After this step, the rise in exhaust gas temperature and the fluctuation in air preheater current are observed. During the heating process, soot blowing and warming of the air preheater tubes are performed. When the temperature reaches 170℃, continuous soot blowing is simultaneously initiated at both the cold and hot ends of the #3 air preheater.

[0011] 2. In this invention, the electric water inlet valves of the #10, #11, and #12 flue gas coolers on the #4 air preheater side are closed one by one, and the closure is confirmed on the spot; the outlet flue gas temperature of the #7, #8, and #9 flue gas coolers is controlled to be no lower than 130°C and no higher than 150°C, and the outlet flue gas temperature of the #10, #11, and #12 flue gas coolers is controlled to be no lower than 90°C. Detailed Implementation

[0012] A method for preventing and controlling air preheater blockage based on unilateral heating pyrolysis, comprising the following steps: (1) Close the electric water inlet valves of flue gas coolers #10, #11, and #12 on the side of air preheater #4 one by one; (2) Gradually close the hot secondary air damper at the outlet of the #3 air preheater from 1% to 0% on-site. At a load of 700MW, the flue gas temperature at the outlet of the #3 air preheater should rise to 160℃. (3) Gradually reduce the opening of the hot secondary air damper 2 at the outlet of the #3 air preheater. If the opening is above 50%, reduce it by 10% per cycle, and if the opening is below 50%, reduce it by 5% per cycle, until it is reduced to 20%. (4) When the outlet flue gas temperature of the #3 air preheater rises to 185°C at a load of 700MW, if the outlet flue gas temperature does not reach 180°C, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero on site. (5) During operation, increase the output of the #4 primary air fan and the #4 blower heater, and raise the inlet air temperature of the #4 air preheater to about 40°C to prevent the #4 air preheater current from fluctuating. (6) During the process of increasing the outlet flue gas temperature of the #3 air preheater, strengthen the on-site inspection of the air preheater and flue gas cooler, check for any abnormal jamming or grinding sounds, and continue to raise the temperature only after the air preheater current is stable. Control it to not exceed 15A. Otherwise, stop the operation and check on-site whether there is any smoke coming out of the induced draft fan expansion joint. (7) When the flue gas temperature of the #3 air preheater rises to 150℃, it should be kept stable for 10 minutes. Then, the flue gas temperature should be increased to 160℃ and kept stable for 10 minutes. Next, the flue gas temperature should be increased to 170℃ and kept stable for 10 minutes. Finally, the flue gas temperature should be increased to 185℃ and kept stable for 4-6 hours. During the stabilization period, the operation of the boiler and desulfurization system should be thoroughly checked. (8) If the flue gas temperature of the #3 air preheater rises too quickly or rises to >200℃, or if the load decreases and the flue gas temperature at the outlet of the #4 air preheater is lower than 90℃, adjust by opening the hot secondary air dampers 2 and 1 at the outlet of the #3 air preheater. (9) After the pyrolysis is completed, open the hot secondary air dampers 2 and 1 at the outlet of the #3 air preheater in sequence. During the recovery process, the rate of change of the flue gas temperature at the outlet of the air preheater should still be controlled to be ≤1℃ / min. (10) Maintain the outlet flue gas temperature of the #3 air preheater between 180℃ and 195℃, closely monitor the air preheater current fluctuations to not exceed 15A, the temperature of the upper and lower bearings of the air preheater <70℃, the temperature of the blower motor and blower bearings <80℃, and the vibration of any blower or blower bearing <4mm / s. (11) When increasing the outlet flue gas temperature of the #3 air preheater, if the outlet header water temperature of the #7, #8, and #9 flue gas coolers is close to the saturation temperature under the corresponding pressure, the inlet water pressure of the flue gas coolers should be increased to 1.5 MPa. If there is still vibration, close the manual inlet and outlet water valves of the heat exchanger group on the spot, and open the drain valve of the heat exchanger group to drain the water in the heat exchanger group to avoid water hammer.

[0013] (12) After the test begins, closely monitor the flue gas temperature at the inlet of the desulfurization absorption tower and the flue gas temperature at the outlet. When the flue gas temperature at the inlet of the absorption tower is greater than 160°C, immediately start the emergency spray cooling. If the temperature continues to rise and the flue gas temperature at the outlet is greater than 65°C, immediately stop the operation.

[0014] The air preheater anti-blocking control method based on unilateral heating pyrolysis, the specific process of step (1) is as follows: close the electric water inlet valves of flue gas coolers #10, #11 and #12 on the side of air preheater #4 one by one, and confirm that they are all closed on the spot; control the outlet flue gas temperature of flue gas coolers #7, #8 and #9 to be no lower than 130℃ and no higher than 150℃, and control the outlet flue gas temperature of flue gas coolers #10, #11 and #12 to be no lower than 90℃.

[0015] The method for preventing blockage of an air preheater based on unilateral heating pyrolysis is described in step (2), in which the hot secondary air damper at the outlet of the #3 air preheater is gradually closed from 1% to 0%, with an opening of more than 50% at 15% per cycle and an opening of less than 40% at 5% per cycle.

[0016] The air preheater anti-blocking control method based on unilateral heating pyrolysis is described above. The specific process of step (3) is as follows: gradually reduce the opening of the hot secondary air damper 2 at the outlet of the #3 air preheater. When the opening is above 50%, reduce it by 10% per cycle, and when the opening is below 50%, reduce it by 5% per cycle. Reduce it to 20%, and increase the flue gas temperature at the outlet of the #4 air preheater at a rate not greater than 1℃ / min to prevent the air preheater from jamming or tripping due to uneven expansion. If the load increases, the hot secondary air damper 2 at the outlet of the #3 air preheater should be opened larger. Strictly control the outlet pressure of the blower to not exceed 4.0kPa.

[0017] The air preheater anti-clogging control method based on unilateral heating pyrolysis, the specific process of step (4) is as follows: When the outlet flue gas temperature of the #3 air preheater rises to 185℃ at a load of 700MW, if the outlet flue gas temperature does not reach 180℃ or above, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero on-site (10% / time for opening above 50%, 5% / time for opening below 50%). According to the rise of the outlet flue gas temperature of the #4 air preheater, the #3 denitrification inlet flue gas damper 2 is closed, not less than 50%, to maintain the stability of the total air volume, oxygen content, and negative pressure in the furnace. After this step, the rise of the exhaust gas temperature and the fluctuation of the air preheater current are observed. During the heating process, the air preheater is blown with soot to warm the tubes. When the temperature rises to 170℃, the cold and hot ends of the #3 air preheater are continuously blown with soot.

Claims

1. A method for preventing and controlling air preheater blockage based on unilateral heating pyrolysis, characterized in that: The method includes the following steps: (1) Close the electric water inlet valves of flue gas coolers #10, #11, and #12 on the side of air preheater #4 one by one; (2) Gradually close the hot secondary air damper at the outlet of the #3 air preheater from 1% to 0% on-site. At a load of 700MW, the flue gas temperature at the outlet of the #3 air preheater should rise to 160℃. (3) Gradually reduce the opening of the hot secondary air damper 2 at the outlet of the #3 air preheater. If the opening is above 50%, reduce it by 10% per cycle, and if the opening is below 50%, reduce it by 5% per cycle, until it is reduced to 20%. (4) When the outlet flue gas temperature of the #3 air preheater rises to 185°C at a load of 700MW, if the outlet flue gas temperature does not reach 180°C, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero on site. (5) During operation, increase the output of the #4 primary air fan and the #4 blower heater, and raise the inlet air temperature of the #4 air preheater to about 40°C to prevent the #4 air preheater current from fluctuating. (6) During the process of increasing the outlet flue gas temperature of the #3 air preheater, strengthen the on-site inspection of the air preheater and flue gas cooler, check for any abnormal jamming or grinding sounds, and continue to raise the temperature only after the air preheater current is stable. Control it to not exceed 15A. Otherwise, stop the operation and check on-site whether there is any smoke coming out of the induced draft fan expansion joint. (7) When the flue gas temperature of the #3 air preheater rises to 150℃, it should be kept stable for 10 minutes. Then, the flue gas temperature should be increased to 160℃ and kept stable for 10 minutes. Next, the flue gas temperature should be increased to 170℃ and kept stable for 10 minutes. Finally, the flue gas temperature should be increased to 185℃ and kept stable for 4-6 hours. During the stabilization period, the operation of the boiler and desulfurization system should be thoroughly checked. (8) If the flue gas temperature of the #3 air preheater rises too quickly or rises to >200℃, or if the load decreases and the flue gas temperature at the outlet of the #4 air preheater is lower than 90℃, adjust by opening the hot secondary air dampers 2 and 1 at the outlet of the #3 air preheater. (9) After the pyrolysis is completed, open the hot secondary air dampers 2 and 1 at the outlet of the #3 air preheater in sequence. During the recovery process, the rate of change of the flue gas temperature at the outlet of the air preheater should still be controlled to be ≤1℃ / min. (10) Maintain the outlet flue gas temperature of the #3 air preheater between 180℃ and 195℃, closely monitor the air preheater current fluctuations to not exceed 15A, the temperature of the upper and lower bearings of the air preheater <70℃, the temperature of the blower motor and blower bearings <80℃, and the vibration of any blower or blower bearing <4mm / s. (11) When increasing the outlet flue gas temperature of the #3 air preheater, if the outlet header water temperature of the #7, #8, and #9 flue gas coolers is close to the saturation temperature under the corresponding pressure, the inlet water pressure of the flue gas coolers should be increased to 1.5 MPa. If there is still vibration, close the manual inlet and outlet water valves of the heat exchanger group on the spot, and open the drain valve of the heat exchanger group to drain the water in the heat exchanger group to avoid water hammer. (12) After the test begins, closely monitor the flue gas temperature at the inlet of the desulfurization absorption tower and the flue gas temperature at the outlet. When the flue gas temperature at the inlet of the absorption tower is greater than 160°C, immediately start the emergency spray cooling. If the temperature continues to rise and the flue gas temperature at the outlet is greater than 65°C, immediately stop the operation.

2. The air preheater anti-clogging control method based on unilateral heating pyrolysis according to claim 1, characterized in that: The specific process of step (1) is as follows: close the electric water inlet valves of the #10, #11 and #12 flue gas coolers on the #4 air preheater side one by one, and confirm that they are all closed on the spot; control the outlet flue gas temperature of the #7, #8 and #9 flue gas coolers to be no lower than 130℃ and no higher than 150℃, and control the outlet flue gas temperature of the #10, #11 and #12 flue gas coolers to be no lower than 90℃.

3. The air preheater anti-clogging control method based on unilateral heating pyrolysis according to claim 2, characterized in that: In step (2), the hot secondary air damper at the outlet of the #3 air preheater is gradually closed from 1% to 0% on-site. For openings above 50%, the damper is closed at 15% per cycle, and for openings below 40%, the damper is closed at 5% per cycle.

4. The air preheater anti-clogging control method based on unilateral heating pyrolysis according to claim 3, characterized in that: The specific process of step (3) is as follows: gradually reduce the opening of the hot secondary air damper 2 at the outlet of the #3 air preheater, with an opening of 10% / time for openings above 50% and 5% / time for openings below 50%, and reduce it to 20%. Increase the flue gas temperature at the outlet of the #4 air preheater at a rate not greater than 1℃ / min to prevent the air preheater from jamming or tripping due to uneven expansion. If the load increases, the hot secondary air damper 2 at the outlet of the #3 air preheater should be opened larger, and the outlet pressure of the blower should be strictly controlled not to exceed 4.0kPa.

5. A method for preventing blockage in an air preheater based on unilateral heating pyrolysis according to claim 4, characterized in that: The specific process of step (4) is as follows: When the 700MW load is reached, the outlet flue gas temperature of the #3 air preheater rises to 185℃. If the outlet flue gas temperature does not reach 180℃ or higher, the #4 denitrification inlet flue gas damper 1 is gradually closed to zero on-site (10% opening per cycle for openings above 50%, and 5% opening per cycle for openings below 50%). The #3 denitrification inlet flue gas damper 2 is closed according to the rise in the outlet flue gas temperature of the #4 air preheater, with a minimum of not less than 50%, to maintain the stability of the total air volume, oxygen content, and negative pressure in the furnace. After this step is completed, the rise in flue gas temperature and the fluctuation of air preheater current are observed. During the heating process, the air preheater is blown with soot to warm the tubes. When the temperature rises to 170℃, continuous soot blowing is simultaneously started at the cold and hot ends of the #3 air preheater.