What is “Dummy Pump” in an LNG Tank used for?

[bizkitgto]

I’m working on a project where we have a large LNG Storage Tank at an LNG Facility. There are several submerged pumps, and each pump can be pulled out and replaced with a dummy. It also calls for a “dummy pump” to be installed for the LNG Cooldown/first-fill. The dummy pump
appears to be a cylinder that just weighs down the foot valve to allow liquid to flow up the pump column. I don’t understand why this is part of the startup.

Can someone explain why we need a dummy pump and what it is supposed to do? Thai appears to be only needed during the tank cooldown and facility startup.

Thanks!

 

[LittleInch]

I think what it is used for is to flow cold gas vapour into the base of the tank to then purge the nitrogen out the top as most LBG tanks nowadays only have top entry for LNG.

You don't want to spin the pumps backwards with gas flow so they take out a pump and insert a dummy pump to weigh down the foot valve and allow gas flow into the base of the tank.

Best to check out the purging and first fill procedure.