Hi, I've recently found a problem in one of my Frame 6 GE GTG. A bit of an overview of the cooling water system, there is no selector switch to determine which cooling water pump is the lead, so by default, 88WC-1 is the main pump2, 88WC-2 will activate when pressure drops to 40PSIG. Current pump discharge when only 1 pump is operating is around 60 psig, however it is hunting and drops below 40 PSIG at an erratic interval, which always cause 88WC-2 pump to activate. Note: deactivation of 88WC-2 is manual by operator. I've tried to operate 88WC-2 as the main pump while open breaker 88WC-1, but it still showed the same symptoms of pressure drop.
Cooling water system is a closed cycle and components cooled by the system are turbine support legs, Atomizing Air Precooler and LO HEX. Water after cooling the AA Precooler, LO HEX and support legs first enters an expansion tank (venting is closed) and then pumped by 88WC to a Finned tube Heat exchanger which will then be used to cool the AA Precooler, LO HEX and support legs to complete the closed cycle.
I was wondering what would cause the hunting/ erratic pressure to drop from 60 to 40 psig? I've observed that around the turbine base at the precooler, there is a metal knocking sound which happened when the pressure drops and is wondering what the cause of the sound could be and whether there is a problem in the precooler.
Also, should the vent on the expansion tank be open during normal operations or venting should only be done during filling of cooling water system to vent out trapped air in the system and then closed?
Apologize for any unclear wording as english is not my main language.
Really appreciate any feedback or info for other part that I should look at regarding the problem.
Cheers
Cooling water system is a closed cycle and components cooled by the system are turbine support legs, Atomizing Air Precooler and LO HEX. Water after cooling the AA Precooler, LO HEX and support legs first enters an expansion tank (venting is closed) and then pumped by 88WC to a Finned tube Heat exchanger which will then be used to cool the AA Precooler, LO HEX and support legs to complete the closed cycle.
I was wondering what would cause the hunting/ erratic pressure to drop from 60 to 40 psig? I've observed that around the turbine base at the precooler, there is a metal knocking sound which happened when the pressure drops and is wondering what the cause of the sound could be and whether there is a problem in the precooler.
Also, should the vent on the expansion tank be open during normal operations or venting should only be done during filling of cooling water system to vent out trapped air in the system and then closed?
Apologize for any unclear wording as english is not my main language.
Really appreciate any feedback or info for other part that I should look at regarding the problem.
Cheers