Canned motor pumps in "dirty" service.

[RGRAJANI]

We are facing repeated bearing and motor failure for Canned Motor Pumps in Sour Water Service duties.

Pumps are as per API 685. Average head is 30 meter, Flow 20m3/hr and fluid temp. 50 Deg C.

During design stage, EPC contractor considered sour water as a clean service. But practically this sour water is dirty and contains solids.

"Back Circulation" is used for motor cooling and bearing lubrication with 60 mesh filter. We believe that solids in the sour water is causing failures of these canned motor pumps. We are working on some solutions to provide external clean flushing fluid.

We would like to know, which type of pumps are normally specified in sour water service (where water contains solids) ? Any temporary/permanent solution is suggested ?

 

[pumpkind]

In order to get some protection to the existing pumps and to asess the nature and magnitude of the 'dirt' problem, use a dual filter system with a switch-over function placed in the suction pipe of the pumps.
If the size of the particles found on these filters xceeds tolerable sizes and/or procentage of mass flow handled - ( check manufacturer's data ) - it will be unavoidable to switch to another type of pump.

 

[trashcanman]

A diaphragm pump might work. They are made to handle dirty fluids/slurries.