Process Water System

The process water system is formed by 1 process water tank, 2 process water pumps and relevant valves and instruments. The process makeup water for FGD system is from main unit process water supply system. Process water for desulphurization island is supplied by one of the two process water pump while the other water pump is for standby. When the water pump outlet pressure is under 4bar in operation, the water pump outlet check valve will close automatically, and when pressure rise to 6 bar, it will open automatically. When water pump outlet chek valve closes and pressure continues to drop to 3.5 bar, or operation pump suddenly pauses, the standby pump will start automatically. Water pump normal outlet operation pressure is about 4-6bar and changes with water volume change. The pressure transmitter is installed on outlet main pipe of the 2 water pumps.

The whole system is set with one process water tank, whose makeup water is mainly from the process water supply system of the main unit. The liquid level of process water tank is controlled in normal scope by opening or closing the inlet motor-driven valve. When the water level is less than 3,000 mm, the motor-driven valve will open automatically and when the water level is above 5,700 mm, it will close automatically. On the makeup water pipe one solenoid flow meter is installed to monitor the supply water volume; on the lower part of the water tank pressure transmitter is installed to do static-pressure liquid level measurement for the water tank, in which flow and water level signal will be sent to DCS to display or participate in interlock.