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RE: pump cavitation

#7832

coker squirrel
Participant

Yes, we have a 1 1/2″ line around the discharge check valve. And you are correct, we do partially open the discharge valve and crack open the 1 1/2″ valve around the discharge valve. We use the discharge from the companion pump through this line (1 1/2″ check valve bypass – we call it our “warmup line”) to slowly warm up the pump with the heater feed from the discharge of the companion heater feed pump. The key difference here is that we warm up the pump with the suction valve closed. We have installed a new line on the suction side of the pump (located close to the suction valve and within the pump isolation). This line goes up to the wash-zone portion of the Fractionator. If you completely warm up the pump with the suction valve closed through this line to the wash-zone, you will clear the pump and discharge line of all light material that may cavitate the companion pump through the revese flow on the suction line. After slowly warming up the pump this way up to around 400°F, you close the warmup line and then slowly open the suction valve. You then close the new line valve at the pump suction and then slowly open the warmup valve again. This puts the pump into a normal warmup standby mode and is ready to start.
I aslo have a wash header in which I use to clear the pump with LGO for maintenance, steam it out to the evacuation system and also to LGO wash all the associated lines after use. This is completely enclosed system, no hydrocarbon ever goes to the atmosphere.
Using this method, you can start your CHGO or CHLGO seal flush before warming up the pump with heater feed. This is recommended to keep the heater feed from ever entering the seals.
This works every time. No more pump cavitations.

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