【Weekly Question on October 8】How should high water level in the drum of a circulating fluidized bed boiler be dealt with?

Release or reduce the inflow of water.

Answer: When the water level in the drum of a circulating fluidized bed boiler is too high, the following measures should be taken: (1) If the water level exceeds +30 mm, an alarm is triggered; the feedwater control should be switched from automatic to manual, and the feedwater valve or the speed of the feedwater pump should be adjusted to reduce the amount of feedwater supplied. (2) Quickly identify the cause and take appropriate action. (3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, a high II alarm is triggered, and the emergency drain valve opens automatically). (4) If the high water level causes the main steam temperature to drop, the desuperheating water valves should be closed immediately, and all the superheater drain valves should be opened. (5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. (6) Stop feeding water to the boiler and activate the economizer recirculation. (7) Open all the superheater and reheater drain valves, and close the desuperheating water valve. (8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

1) If the drum water level is above +30 mm, a high water level alarm is triggered; the feedwater control is automatically switched to manual mode, and the feedwater valve or the speed of the feedwater pump is adjusted to reduce the amount of feedwater supplied. 2) Quickly identify the cause and take appropriate action. 3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, an alarm is triggered for high II value, and the emergency drain valve opens automatically). 4) If the high water level causes a drop in the main steam temperature, the feedwater cooling valve should be closed immediately, and all the superheater drain valves should be opened. 5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. 6) Stop feeding water to the boiler and activate the economizer recirculation. 7) Open all the superheater and reheater drain valves, and close the feedwater cooling water valve. 8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

Answer: When the water level in the drum of a circulating fluidized bed boiler is too high, the following measures should be taken: (1) If the water level exceeds +30 mm, an alarm is triggered; the feedwater control should be switched from automatic to manual, and the feedwater valve or the speed of the feedwater pump should be adjusted to reduce the amount of feedwater supplied. (2) Quickly identify the cause and take appropriate action. (3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, a high II alarm is triggered, and the emergency drain valve opens automatically). (4) If the high water level causes the main steam temperature to drop, the desuperheating water valves should be closed immediately, and all the superheater drain valves should be opened. (5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. (6) Stop feeding water to the boiler and activate the economizer recirculation. (7) Open all the superheater and reheater drain valves, and close the desuperheating water valve. (8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

1) If the drum water level is above +30 mm, a high water level alarm is triggered; the feedwater control is automatically switched to manual mode, and the feedwater valve or the speed of the feedwater pump is adjusted to reduce the amount of feedwater supplied. 2) Quickly identify the cause and take appropriate action. 3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, an alarm is triggered for high II value, and the emergency drain valve opens automatically). 4) If the high water level causes a drop in the main steam temperature, the feedwater cooling valve should be closed immediately, and all the superheater drain valves should be opened. 5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. 6) Stop feeding water to the boiler and activate the economizer recirculation. 7) Open all the superheater and reheater drain valves, and close the feedwater cooling water valve. 8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

(1) If the drum water level is above +30 mm, a high water level alarm is triggered; the feedwater control is automatically switched to manual mode, and the feedwater valve or the speed of the feedwater pump is adjusted to reduce the amount of feedwater supplied. (2) Quickly identify the cause and take appropriate action. (3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, a high II alarm is triggered, and the emergency drain valve opens automatically). (4) If the high water level causes the main steam temperature to drop, the desuperheating water valves should be closed immediately, and all the superheater drain valves should be opened. (5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. (6) Stop feeding water to the boiler and activate the economizer recirculation. (7) Open all the superheater and reheater drain valves, and close the desuperheating water valve. (8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

1) If the drum water level is above +30 mm, a high water level alarm is triggered; the feedwater control is automatically switched to manual mode, and the feedwater valve or the speed of the feedwater pump is adjusted to reduce the amount of feedwater supplied. 2) Quickly identify the cause and take appropriate action. 3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, an alarm is triggered for high II value, and the emergency drain valve opens automatically). 4) If the high water level causes a drop in the main steam temperature, the feedwater cooling valve should be closed immediately, and all the superheater drain valves should be opened. 5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. 6) Stop feeding water to the boiler and activate the economizer recirculation. 7) Open all the superheater and reheater drain valves, and close the feedwater cooling water valve. 8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

1. Reduce it by lowering the wastewater discharge; 2. Lower it by controlling the inflow rate. 3. Remove some through the strainer. 4. Check the cause of the high water level.

Answer: When the water level in the drum of a circulating fluidized bed boiler is too high, the following measures should be taken: (1) If the water level exceeds +30 mm, an alarm is triggered; the feedwater control should be switched from automatic to manual, and the feedwater valve or the speed of the feedwater pump should be adjusted to reduce the amount of feedwater supplied. (2) Quickly identify the cause and take appropriate action. (3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, a high II alarm is triggered, and the emergency drain valve opens automatically). (4) If the high water level causes the main steam temperature to drop, the desuperheating water valves should be closed immediately, and all the superheater drain valves should be opened. (5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. (6) Stop feeding water to the boiler and activate the economizer recirculation. (7) Open all the superheater and reheater drain valves, and close the desuperheating water valve. (8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.

How should high drum water level in a circulating fluidized bed boiler be dealt with? (1) If the drum water level is above +30 mm, a high water level alarm is triggered; the feedwater control is automatically switched to manual mode, and the feedwater valve or the speed of the feedwater pump is adjusted to reduce the amount of feedwater supplied. (2) Quickly identify the cause and take appropriate action. (3) If the treatment is ineffective, the emergency drain valve or the blowdown valve of the lower header should be opened to release water (when the drum water level rises to +200 mm, a high II alarm is triggered, and the emergency drain valve opens automatically). (4) If the high water level causes the main steam temperature to drop, the desuperheating water valves should be closed immediately, and all the superheater drain valves should be opened. (5) When the drum water level rises to +300 mm, the boiler’s MFT protection should activate; otherwise, manual MFT operation should be performed to shut down the boiler urgently. (6) Stop feeding water to the boiler and activate the economizer recirculation. (7) Open all the superheater and reheater drain valves, and close the desuperheating water valve. (8) If the turbine blades are not damaged, ignition can be restarted once the water level is normal.