A flexible peak load control method for realizing CFB unit shutdown without stopping the machine

Abstract

The present invention relates to the field of peak load regulation technology, and specifically to a flexible peak load regulation control method for realizing non-stop operation of CFB units. In the process of flexible peak load regulation, the present invention prevents shutdown during furnace trip protection by decoupling the large interlocking protection of the machine, electricity, and furnace; achieves matching of water supply by maintaining a reasonable water-coal ratio; ensures the safety of the high-pressure cylinder of the steam turbine by monitoring the exhaust temperature of the high-pressure cylinder and operating the high-exhaust ventilation valve; prevents steam-water shock to the low-pressure cylinder of the steam turbine by controlling the superheat of the steam inlet of the steam turbine, and realizes the safe operation of the low-pressure cylinder of the steam turbine; starts the induced draft fan, the secondary fan, and the primary fan in sequence, and adds coal after the boiler is fully fluidized, so that no auxiliary fuel oil is needed when the load is adjusted back. The above scheme realizes flexible peak load regulation without stopping the CFB unit during shutdown, improves the flexibility of unit operation, and solves the problem of absorbing new energy electricity in the face of the increasing proportion of new energy installed capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of unit peak regulation, and in particular to a flexible peak regulation control method for realizing a CFB unit without stopping the furnace. Background Art

[0002] Circulating Fluidized Bed (CFB) combustion technology is currently recognized as the most promising "clean" coal-fired technology. It has the advantages of wide adaptability to coal types, strong load regulation capability, low nitrogen oxide emissions, fast load regulation, and high combustion efficiency. CFB boilers use circulating fluidized bed combustion of high-temperature solid particle materials, with large heat capacity in the furnace and uniform furnace temperature distribution. Therefore, the circulating fluidized bed has good deep peak regulation performance.

[0003] Due to the volatility of renewable energy power generation, the consumption of renewable energy power plants has become an urgent problem to be solved. Therefore, it has become an inevitable trend for thermal power generating units to improve their operating flexibility and carry out deep peak regulation. Summary of the invention

[0004] In view of the above problems, the present invention provides a flexible peak load regulation control method for realizing the CFB unit shutdown without stopping the machine.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a flexible peak load regulation control method for realizing a CFB unit shutdown without stopping the machine, comprising the following steps:

[0007] Step 1: After receiving the deep peak regulation signal of the unit, the interlock protection of the generator, electricity and boiler is disconnected to prevent the turbine from shutting down when the boiler is disconnected; when the active power of the generator drops to 100-110MW, the 6KV plant power is cut to the standby transformer belt;

[0008] Step 2: first reduce the amount of coal fed to the boiler, then reduce the amount of air fed to the boiler, so that the electrical load is reduced, the steam temperature is stabilized, and the gas pressure decreases;

[0009] Step 3, maintain the water-coal ratio and gradually reduce the water supply to achieve water supply matching;

[0010] Step 4, stop the coal feeder and the fan in turn, and trip the boiler;

[0011] Step 5: After the boiler trips and stops operating, feedwater control and steam turbine control are maintained;

[0012] Step 6, high pressure cylinder protection during peak load regulation;

[0013] Step 7, protecting the low-pressure cylinder during peak load regulation;

[0014] Step 8, performing reverse power protection for the generator during peak load regulation;

[0015] Step 9, performing furnace starting control without adding fuel oil.

[0016] Furthermore, in step 2, reducing the amount of coal fed to the boiler is achieved by reducing the speed of the weighing coal feeder belt, which is 90-900rpm, and the speed of the coal feeder is reduced by 30 revolutions each time; reducing the amount of air fed into the boiler is specifically: in coordination with the reduction in the amount of coal fed, reducing the speed of the boiler fan inverter, closing the boiler secondary air damper and the coal spreading air damper to reduce the amount of air fed into the boiler; the specific method of reducing the amount of air fed into the boiler by reducing the speed of the boiler fan inverter, closing the boiler secondary air damper and the coal spreading air damper is: the boiler fan output is adjusted by the configured inverter, and a speed reduction instruction is issued to the inverter through the DCS system to reduce the fan output.

[0017] Furthermore, the specific process of step 3 is as follows: the water-coal ratio is the main means of adjusting the main steam temperature, and the change of the midpoint temperature can quickly respond to the change of the water-coal ratio. Only by maintaining the temperature of this point stable can the stability of the main steam temperature be guaranteed. In the peak control operation, the water supply is adjusted according to the fuel amount to achieve the matching of the water supply. According to the midpoint temperature, the appropriate water-coal ratio is guaranteed to maintain the corresponding relationship between the load and the water-coal ratio, and the water-coal ratio is prevented from fluctuating greatly due to the imbalance of the water-coal ratio, so as to ensure that the metal wall temperature of each heating surface of the boiler is within the normal range; the water supply flow is corrected according to the outlet temperature of the steam-water separator, and the water supply is increased when the superheat is higher than the set value; the water supply is reduced when the superheat is lower than the set value; when the water-coal ratio is unbalanced due to the step disturbance of the combustion condition, the automatic failure of the water supply or the manual jump causes the water-coal ratio to be unbalanced, the water supply is cut to the manual mode, the corresponding relationship between the load and the water-coal ratio is maintained, and the water supply is adjusted to restore the balance, but the combustion and water supply should be adjusted at the same time as much as possible.

[0018] Furthermore, the specific operation of stopping the coal feeder in step 4 is: switching the coal feeder from automatic to manual, and stopping all coal feeders; the specific operation of stopping the fan in step 4 is: when the oxygen content rises to 15%, stop the primary fan, secondary fan and induced draft fan in sequence; stopping the primary fan is: the inverter is automatically released, the inlet adjustment damper and the inverter adjustment are gradually reduced to the minimum 15HZ, the inlet adjustment damper is fed back to less than 5%, the fan motor is stopped, the primary fan outlet damper is closed, and the inlet damper is manually closed; stopping the secondary fan is: the inverter is automatically released To stop the induced draft fan: check that the frequency conversion control of the other fan is in the automatic position, or that the other fan has stopped, turn off the frequency conversion of the induced draft fan at a certain rate to 10Hz, gradually close the inlet adjustment damper to zero, pay attention to the changes in furnace pressure, stop the induced draft fan motor, interlock and close the inlet damper of the stopped induced draft fan, check that the stopped fan stops speed and there is no reverse rotation, and stop the cooling fan of the induced draft fan.

[0019] Furthermore, the specific process of maintaining feed water control and turbine control in step 5 is: after the boiler trips and stops operating, the turbine speed is maintained at 3000rpm, and the load reduction rate is maintained at 7WM / min; at the same time, the feed water is adjusted to match the electrical load, and the feed water volume is gradually reduced to 50t / h and maintained to ensure that the main steam temperature does not exceed the limit.

[0020] Furthermore, the specific process of step 6 is: keep the electrical load continuously decreasing and matching the water supply flow, monitor the high-pressure cylinder exhaust steam temperature, and open the high-exhaust ventilation valve when the temperature is greater than 427°C.

[0021] Furthermore, the specific process of step 7 is: by limiting the inlet steam temperature of the turbine, controlling the inlet steam superheat of the turbine to be greater than 50°C, preventing the temperature of the steam after doing work in the subsequent stages of the low-pressure cylinder from being lower than the saturation temperature at the pressure of this stage and becoming wet steam, thereby causing steam-water shock to the turbine.

[0022] Furthermore, the specific process of step 8 is as follows: after the boiler trips, immediately close the superheater, reheater cooling water adjustment door, electric door, and each extraction valve of the extraction system; according to the change of the main steam pressure, immediately close the turbine steam inlet valve; maintain the unit load at 3MW by matching the feed water, ensure that the steam temperature drops slowly, keep the steam temperature drop rate no more than 1°C / min, and maintain the unit load at 3MW for 1 hour.

[0023] Furthermore, the specific process of step 9 is as follows: conduct a comprehensive inspection of the boiler and auxiliary transfer equipment, and ensure that under the condition that the air channel has been established, start an induced draft fan, adjust the furnace negative pressure to -60Pa~-200Pa, start a high-pressure fluidizing fan, and control the ventilation volume of each "J" valve air nozzle within the fixed air volume table value range, start the selected secondary fan, maintain the secondary air volume at the minimum air volume, and make the secondary wind box air pressure greater than the boiler bed pressure, and at the same time adjust each secondary air damper to an appropriate opening to ensure the minimum air volume of each secondary air outlet, avoid the bed material from flowing back to the secondary air duct when the primary fan is started, start two primary fans, and ensure that the primary air volume is greater than the minimum fluidizing air volume of 180000Nm 3 / h, maintaining a minimum combustion air volume of about 291000Nm 3 / h. Before coal is added, the primary air required for fluidization will cause the bed material to cool down. Therefore, within 60s after the primary fan is started, carefully monitor the bed temperature value to make the boiler bed temperature greater than 650℃. After waiting for the boiler to be fully fluidized, add 100t / h of coal into the furnace. If the O2 content in the boiler drops to 6%, it means that the boiler is successfully ignited and the boiler resumes operation. At this time, the machine, electricity and furnace are interlocked, and the primary air volume and coal supply are continuously adjusted to control the bed temperature according to the changes in combustion. If the temperature rises rapidly, the primary air can be appropriately increased and the coal supply can be reduced. If the temperature drops, the primary air can be appropriately reduced, but it cannot be lower than the critical air volume, and the coal supply can be increased according to the specific situation until the combustion is stable. Control the bed temperature to operate at 850-950℃. When the combustion is stable, adjust the steam parameters. When the steam parameters meet the steam paralleling requirements, you can follow the steam paralleling steps to parallel steam or directly supply steam.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention prevents shutdown during boiler trip protection by decoupling the electromechanical furnace chain protection during the flexible peak-shaving process; maintains a reasonable water-coal ratio to achieve matching of the water supply; monitors the exhaust temperature of the high-pressure cylinder and operates the high-exhaust ventilation valve to ensure the safety of the high-pressure cylinder of the steam turbine; prevents steam-water shock on the low-pressure cylinder of the steam turbine by controlling the superheat of the steam inlet to achieve safe operation of the low-pressure cylinder of the steam turbine; starts the induced draft fan, secondary fan, and primary fan in sequence, and adds coal after the boiler is fully fluidized, so that there is no need to add auxiliary fuel oil when the load is adjusted back, etc., to achieve flexible peak-shaving of the CFB unit without stopping the furnace, thereby improving the flexibility of the unit operation and solving the problem of absorbing new energy electricity in the face of the increasing proportion of new energy installed capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process of the present invention;

[0027] Figure 2It is a schematic diagram of the device of the present invention;

[0028] Figure 3 It is a schematic diagram of boiler feed water of the present invention;

[0029] Figure 4 It is a schematic diagram of the flow of soda of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is specifically and detailedly described below in conjunction with the embodiments of the present invention and the accompanying drawings. It should be noted that for ordinary technicians in this field, several modifications and improvements can be made without departing from the principle of the present invention, which should also be regarded as belonging to the protection scope of the present invention.

[0031] like Figure 1 As shown: a flexible peak-shaving control method for realizing shutdown of CFB units without stopping the machine, including preparation before peak-shaving, control during peak-shaving, high-pressure cylinder protection measures during peak-shaving, low-pressure cylinder protection measures during peak-shaving, reverse power protection measures during peak-shaving, and furnace start-up control without adding auxiliary fuel oil.

[0032] To ensure that the boiler will not trip when it stops burning during deep peak regulation, after receiving the deep peak regulation signal of the unit, the machine, electricity and boiler interlocking protection are first de-energized to prevent the turbine and generator from tripping one after another after the boiler BT, and then peak regulation control, high-pressure cylinder protection, low-pressure cylinder protection, generator anti-reverse power protection, and starting the furnace without adding auxiliary fuel are carried out.

[0033] After disconnecting the interlocking protection of the machine, electricity and boiler, start the peak load control operation, reduce the amount of coal fed to the boiler, reduce the amount of air sent to the boiler, so that the electrical load is reduced, the steam temperature is stable, and the gas pressure drops; maintain the water-coal ratio, gradually reduce the water feed, and achieve water feed matching; stop the coal feeder and fan in turn, and trip the boiler (BT); maintain water feed control and maintain turbine control.

[0034] Reduce the amount of coal fed to the boiler and the amount of air sent into the boiler: Reduce the amount of coal fed to the boiler by reducing the belt speed of the weighing coal feeder, which is 90-900rpm, and reduce the speed of the coal feeder by 30 revolutions each time. In conjunction with the reduction in the amount of coal fed, reduce the amount of air sent into the boiler by reducing the speed of the boiler fan inverter, closing the boiler secondary air damper and the coal-spreading wind damper. Reduce the coal first and then the wind to avoid oxygen-deficient combustion. The specific method of reducing the amount of air sent into the boiler by reducing the speed of the boiler fan inverter, closing the boiler secondary air damper and the coal-spreading wind damper is: the boiler fan output is adjusted by the configured inverter, and a speed reduction instruction is issued to the inverter through the DCS system to reduce the fan output;

[0035] Maintain the water-coal ratio, gradually reduce water, and achieve matching of feed water: the water-coal ratio is the main means of adjusting the main steam temperature, and the change of the midpoint temperature can quickly respond to the change of the water-coal ratio. Only by maintaining the temperature stability of this point can the stability of the main steam temperature be guaranteed. In the peak control operation, the feed water volume is adjusted according to the fuel amount to achieve the matching of the feed water volume. According to the midpoint temperature, the appropriate water-coal ratio is guaranteed, the corresponding relationship between the load and the water-coal ratio is maintained, and the water-coal ratio is prevented from fluctuating greatly due to the imbalance of the water-coal ratio, and the metal wall temperature of each heating surface of the boiler is within the normal range; the feed water flow rate is corrected according to the outlet temperature of the steam-water separator, and the feed water volume is increased when the superheat is higher than the set value; the feed water volume is reduced when the superheat is lower than the set value; the water-coal ratio is unbalanced due to step disturbance of the combustion condition, automatic failure of the feed water or manual jump, etc., and the feed water should be cut to manual mode, the corresponding relationship between the load and the water-coal ratio is maintained, and the feed water volume is adjusted to restore the balance, but the combustion and feed water adjustment should be avoided as much as possible.

[0036] The coal feeder and the fan stop running in turn, and the boiler trips: the specific operation of stopping the coal feeder is: switching the coal feeder from automatic to manual, and stopping all coal feeders. When the oxygen content rises to 15%, stopping the fan operation is specifically: stopping the primary fan, secondary fan and induced draft fan in turn; stopping the primary fan: the inverter is released automatically (frequency conversion state), and the inlet adjustment damper and the inverter adjustment are gradually reduced to a minimum of 15HZ, and the inlet adjustment damper is fed back to less than 5%, and the fan motor is stopped, the primary fan outlet damper is closed, and the inlet damper is manually closed. Stopping the secondary fan: the inverter is released automatically (frequency conversion state), and the inlet adjustment damper and the inverter adjustment are gradually reduced to a minimum of 15HZ, and the inlet adjustment damper is fed back to less than 5%, and the fan motor is stopped, the secondary fan outlet damper is closed, and the inlet damper is manually closed. Stop the induced draft fan: Check that the frequency conversion control of the other fan is in the automatic position, or the other fan has stopped, and turn off the frequency conversion of the induced draft fan at a certain rate to 10Hz, gradually close the inlet adjustment damper to zero, pay attention to the changes in furnace pressure, and stop the induced draft fan motor. Interlock and close the inlet damper of the stopped induced draft fan, check the speed of the stopped fan, no reverse rotation, and stop the cooling fan of the induced draft fan.

[0037] Maintain feedwater control and steam turbine control: After the boiler is shut down, the steam turbine and generator will not be shut down, and the steam generated by the waste heat of the boiler can continue to generate electricity. When the boiler is shut down, maintain the turbine speed at 3000rpm and the load reduction rate at 7WM / min. At the same time, adjust the feedwater to match the electrical load, gradually reduce the feedwater volume to 50t / h and maintain it, pay attention to the superheat at the intermediate point, and ensure that the main steam temperature does not exceed the limit.

[0038] High-pressure cylinder protection: Keep the electrical load continuously decreasing and matching the water supply flow, monitor the exhaust temperature of the high-pressure cylinder, and open the high-exhaust ventilation valve when the temperature is greater than 427℃.

[0039] Low-pressure cylinder protection: When the boiler trips, the inlet steam temperature of the steam turbine is limited to control the inlet steam superheat of the steam turbine to be greater than 50°C, to prevent the temperature of the steam after the low-pressure cylinder has done work from being lower than the saturation temperature at this stage pressure and becoming wet steam, thus causing steam-water shock to the steam turbine;

[0040] Generator anti-reverse power protection: After the boiler is ignited, immediately close the superheater, reheater cooling water adjustment door, electric door, and all steam extraction valves of the extraction system. According to the change of the main steam pressure, immediately close the steam inlet valve of the turbine, and maintain the unit load at 3MW through the matching of feed water to ensure that the steam temperature drops slowly, and the rate of decline is no more than 1℃ / min, and the unit load is maintained at 3MW for 1 hour. Feed water control: Keep the steam temperature drop rate no more than 1℃ / min, reduce the unit load, and ensure that the superheat of the steam-water separator decreases slowly. When the water level in the water storage tank begins to rise, the boiler will enter the wet state from dry state. After the boiler feed water main valve is fully closed, the boiler feed water bypass regulating valve is adjusted to ensure that the boiler feed water flow is stable. During the ignition process, the feed water pump is used to maintain the feed water flow at 50t / h.

[0041] Control operation for starting the furnace without adding auxiliary oil: conduct a comprehensive inspection of the boiler and auxiliary transfer equipment, and ensure that under the condition that the air channel has been established, start an induced draft fan, adjust the furnace negative pressure (-60Pa< furnace negative pressure<-200Pa), start a high-pressure fluidizing fan, and control the ventilation volume of each "J" valve air nozzle within the fixed air volume meter value range, start the selected secondary fan, maintain the secondary air volume at the minimum air volume, and make the secondary wind box air pressure greater than the boiler bed pressure, and at the same time adjust the secondary air dampers to the appropriate opening to ensure the minimum air volume of each secondary air outlet, avoid the bed material from flowing back to the secondary air duct when the primary fan is started, start two primary fans, ensure that the primary air volume is greater than the minimum fluidizing air volume of 180000Nm3 / h, and maintain the minimum combustion air volume of about 291000Nm3 / h. Before coal is added, the primary air required for fluidization will cause the bed material to cool down, so within 60s after the primary fan is started, it is recognized that Monitor the bed temperature value to make the boiler bed temperature greater than 650℃. Wait for the boiler to be fully fluidized, and then add 100t / h of coal into the furnace. If the O2 content in the boiler drops to 6%, it means that the boiler is successfully ignited and the boiler resumes operation. At this time, the machine, electricity, and furnace are interlocked, and the primary air volume and coal supply are continuously adjusted to control the bed temperature according to the combustion changes. If the temperature rises quickly, the primary air can be appropriately increased and the coal supply can be reduced. If the temperature drops, the primary air can be appropriately reduced, but it cannot be lower than the critical air volume, and the coal supply can be increased according to the specific situation until the combustion is stable. The bed temperature is controlled to operate at 850-950℃. When the combustion is stable, adjust the steam parameters. When the steam parameters meet the requirements for steam connection, steam connection can be carried out according to the steam connection steps or steam can be directly supplied. The boiler resumes normal operation, and the flexible peak-shaving control operation is completed without stopping the boiler.

[0042] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A flexible peak load control method for realizing CFB unit shutdown without stopping the machine, characterized in that: The following steps are involved: Step 1: After receiving the deep peak regulation signal of the unit, the interlock protection of the generator, electricity and boiler is disconnected to prevent the turbine from shutting down when the boiler is disconnected; when the active power of the generator drops to 100-110MW, the 6KV plant power is cut to the standby transformer belt; Step 2: first reduce the amount of coal fed to the boiler, then reduce the amount of air fed to the boiler, so that the electrical load is reduced, the steam temperature is stabilized, and the gas pressure decreases; Step 3, maintain the water-coal ratio and gradually reduce the water supply to achieve water supply matching; Step 4, stop the coal feeder and the fan in turn, and trip the boiler; Step 5: After the boiler trips and stops operating, feedwater control and steam turbine control are maintained; Step 6, high pressure cylinder protection during peak load regulation; Step 7, protecting the low-pressure cylinder during peak load regulation; Step 8, performing reverse power protection for the generator during peak load regulation; The specific process is as follows: after the boiler trips, immediately close the superheater and reheater cooling water adjustment doors and electric doors, and close the steam extraction valves of the steam extraction system. According to the change of the main steam pressure, immediately close the steam turbine steam inlet valve, and maintain the unit load at 3MW through the matching of feed water, ensuring that the steam temperature drops slowly, keeping the steam temperature drop rate no more than 1℃ / min, and maintaining the unit load at 3MW for 1 hour; Step 9, performing furnace starting control without adding fuel oil.

2. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: In step 2, reducing the amount of coal fed to the boiler is achieved by reducing the speed of the weighing coal feeder belt, which is 90-900rpm, and the speed of the coal feeder is reduced by 30 revolutions each time; reducing the amount of air fed into the boiler is specifically: in coordination with the reduction in the amount of coal fed, reducing the speed of the boiler fan inverter, closing the boiler secondary air damper and the coal spreading air damper to reduce the amount of air fed into the boiler; the specific method of reducing the amount of air fed into the boiler by reducing the speed of the boiler fan inverter, closing the boiler secondary air damper and the coal spreading air damper is: the boiler fan output is adjusted by the configured inverter, and a speed reduction instruction is issued to the inverter through the DCS system to reduce the fan output.

3. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: The specific process of step 3 is as follows: in the peak control operation, the water supply is adjusted according to the fuel amount to achieve the matching of the water supply, and the appropriate water-coal ratio is guaranteed according to the midpoint temperature, the corresponding relationship between the load and the water-coal ratio is maintained, and the large fluctuation of parameters caused by the imbalance of the water-coal ratio is prevented, so as to ensure that the metal wall temperature of each heating surface of the boiler is within the normal range; the water supply flow is corrected according to the outlet temperature of the steam-water separator, and the water supply is increased when the superheat is higher than the set value; the water supply is reduced when the superheat is lower than the set value; when the water-coal ratio is unbalanced due to a step disturbance in the combustion condition, automatic failure of the water supply or manual tripping, the water supply is switched to manual mode, the corresponding relationship between the load and the water-coal ratio is maintained, and the water supply is adjusted to restore the balance, but simultaneous adjustment of combustion and water supply should be avoided as much as possible.

4. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: The specific operation of stopping the coal feeder in step 4 is: switching the coal feeder from automatic to manual and stopping all coal feeders; the specific operation of stopping the fan in step 4 is: when the oxygen content rises to 15%, stop the primary fan, secondary fan and induced draft fan in sequence; stop the primary fan by releasing the frequency converter automatically, gradually reduce the inlet adjustment damper and the frequency converter adjustment to the minimum 15Hz, feedback the inlet adjustment damper to below 5%, stop the fan motor, close the primary fan outlet damper, and manually close the inlet damper; stop the secondary fan by releasing the frequency converter automatically, gradually Step by step, reduce the inlet adjustment damper and inverter adjustment to the minimum 15Hz, the inlet adjustment damper feedback is below 5%, stop the fan motor, interlock and close the secondary fan outlet damper, and manually close the inlet damper; to stop the induced draft fan: check that the other fan frequency conversion control is in the automatic position, or the other fan has stopped, close the induced draft fan frequency conversion to 10Hz at a certain rate, gradually close the inlet adjustment damper to zero, pay attention to the changes in furnace pressure, stop the induced draft fan motor, interlock and close the inlet damper of the stopped induced draft fan, check that the stopped fan stops speed and there is no reverse, and stop the cooling fan of the induced draft fan.

5. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: The specific process of maintaining feed water control and turbine control in step 5 is: after the boiler trips and stops operating, maintain the turbine speed at 3000rpm and keep the load reduction rate at 7WM / min; at the same time, adjust the feed water to match the electrical load, and gradually reduce the feed water volume to 50t / h and maintain it to ensure that the main steam temperature does not exceed the limit.

6. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: The specific process of step 6 is: keep the electrical load continuously decreasing and matching the water supply flow, monitor the high-pressure cylinder exhaust steam temperature, and open the high-exhaust ventilation valve when the temperature is greater than 427°C.

7. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: The specific process of step 7 is: by limiting the inlet steam temperature of the turbine, controlling the superheat of the inlet steam of the turbine to be greater than 50°C, preventing the temperature of the steam after doing work in the subsequent stages of the low-pressure cylinder from being lower than the saturation temperature at this stage pressure, turning into wet steam and causing steam-water shock to the turbine.

8. A flexible peak load regulation control method for realizing CFB unit shutdown without stopping the machine according to claim 1, characterized in that: The specific process of step 9 is as follows: conduct a comprehensive inspection of the boiler and auxiliary transfer equipment, and ensure that the air channel has been established, start an induced draft fan, adjust the furnace negative pressure to -60Pa ~ -200Pa, start a high-pressure fluidizing fan, and control the ventilation volume of each "J" valve air nozzle within the fixed air volume meter value range, start the selected secondary fan, maintain the secondary air volume at the minimum air volume, and make the secondary wind box air pressure greater than the boiler bed pressure, and at the same time adjust each secondary air damper at a suitable opening to ensure the minimum air volume of each secondary air outlet, avoid the bed material from flowing back to the secondary air duct when the primary fan is started, start two primary fans, and ensure that the primary air volume is greater than the minimum fluidizing air volume of 180000Nm 3 / h, maintaining minimum combustion air volume of 291000Nm 3 / h. Before coal is added, the primary air required for fluidization will cause the bed material to cool down. Therefore, within 60s after the primary fan is started, carefully monitor the bed temperature value to make the boiler bed temperature greater than 650℃. After waiting for the boiler to be fully fluidized, add 100t / h of coal into the furnace. If the O2 content in the boiler drops to 6%, it means that the boiler is successfully ignited and the boiler resumes operation. At this time, the machine, electricity and furnace are interlocked, and the primary air volume and coal supply are continuously adjusted to control the bed temperature according to the changes in combustion. If the temperature rises rapidly, the primary air can be appropriately increased and the coal supply can be reduced. If the temperature drops, the primary air can be appropriately reduced, but it cannot be lower than the critical air volume, and the coal supply can be increased according to the specific situation until the combustion is stable. Control the bed temperature to operate at 850-950℃. When the combustion is stable, adjust the steam parameters. When the steam parameters meet the steam paralleling requirements, you can follow the steam paralleling steps to parallel steam or directly supply steam.

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