Dear all,
Recently our recycle gas compressor got tripped due to high level, we have got two surface condensate pumps, one is driven by steam and other is by electric driven. Steam driven condensate pump is on maintenance, blinding of the suction and discharge lines are done after closing suction valve.
After maintenance of steam driven condensate pump, lining up of it is planned, before opening the suction valve whose upstream pressure is around -0.4kgf/cm2 abs, the downstream line is primed through priming line available u/s of pump discharge check valve connected to surface condenser top whose pressure is -0.9kgf/cm2 abs.
After opening the suction valve, the other pump stopped developing pressure, the level in surface condenser level raised in 3-4 minutes to 90% and RGC got tripped.
My 1st question is, what could go wrong in electric driven pump while opening the suction valve of standby pump??
Suppose if the trapped air in the downstream of suction valve due to improper priming is present, Is it possible to the trapped air to travel to the suction line of other pump? Kindly help me in understanding this. thank you.