flowserve dmx pump overheating

[geliberman]

can anybody advise me how can I solve the pump overheating.
I have a flowserve DMX pump, the pump bearings has failure due to overheating. Overheating is due to low flow, can I use an ARC valve to increase the flow and modify the pump working piont?

 

[Pumpsonly]

You left out the motor effcy in your motor output calculation.

Base on the name plate details the effcy of the motor at full load is 95%.

From the pump curve the BkW at 221 m3/hr is about 750kW which is 75% of motor full load. The PF and effcy at 75% load is expected to drop 1~2 percentage point.The actual value can only be known from the motor test data.

From motor running current of 86.6 provided, the out put is about
840 kW which is higher the pump curve. But than again we are not sure how accurate are the operating data provided.

Btw, oil ring is not a cooling method, it i just to help splash oil on to the bearing and shaft.

 

[PumpSmart]

geliberman,
I based on yout previous post:
"pump model: flowserve 6x11 7stages
speed:2965 rpm
Capacity: 288 m3/h
Head: 875mactual head:1025m"
But based on your last post (221m3/hr@920m)you are around 61% BEP, it is like 80% as reability capacity factor so it sounds aceptable but, yes, it probably will improve but it seems like is not cause related to hot motor bearing. In other hand P&ID depends of your process and variables and varies site to site.
But if low flow was an issue, pump bearings/mech seals was a problem with some vibration but as your previous post it did not happen.
Increment of power, from expected 750 KW to 840 KW (estimated by Pumpsonly) could be motor symptom since 221m3/hr@920mm (I asumme as field data) is very close to performance curve (lab curve you sent previously, so pump is not out of performance).
So mainly you have a hot bearing motor problem plus high motor power consumption.
I review some GE Motor literature, and it could be a several things like oil level, oil type, oil ring position, oil quality, sleeve bearing radial clearance, and says 41% of motor problemas are related to bearings. GE says that normal temp for noncontact bearing is around 95C for Custom 8000 series:

http://www.geindustrial.com.br/download/manuais/motores/espanhol/geep145e.pdf

Page 18.
(it is in spanish, i look in english in GE web site, but is not available)
Maintenance people could help you with some data like complete last motor diagnosis and tell you how old is this motor?, temperature bearing trend (so it is always near to 80C? trend is very important), if stand by motor has the same problem, if a thermogram is available, when did last non-contatc bearing repair, etc.
I hope respectfully, it helps