SRS- thanks for the reply. Here are the answers to your questions, along with some additional information.
“In your pits do you have any air or n2 sweep? Are your vapors routed directly to the incinerator?” We have a continuous ambient air sweep pulled across the pit by a steam powered eductor with the gases routed directly to the incinerator. We also have the offgas return stream from our out of pit degassing tower returning to the pit vapor space. Our problems appear to have started at the same time we upgraded the pumps from 1800 rpm to 3600 rpm and moved the degassing function out of the pit.
We are finding a very hard, very well adhered metallic build up on the internal clearances of our pumps in the upper intermediate bearing. This material is closing up the bushing clearance by up to 0.018″. We have to machine the buildup off the bushings.
“Your jacketing steam? What pressure do you run at? 50#? 70#? ” We have the jacket steam to the pumps set at 35psig and monitored on operator rounds 4x per day. We also have bypass valves open around the condensate trap on the discharge to keep the steam in the jacket from superheating.
“If you had a TI, that would be helpful in checking if your pumps are seizing from running your jacketingsteam at the wrong temperature. Without a TI, take a heat gun and perform a temperature survey?” The jacket steam is confirmed at 35psig. The bulk temperature of the sulfur in the pit is unknown. We have a project in the works to add instrumentation to the pit and pumps, but as projects go it’s out a ways.
“When you take your pumps out of service for maintenance, do you follow a warm up procedure so it doesn’t seize up? I would work with your sulfur pump vendor and double check if you are following the correct reliability practices. ” Yes we do. We don’t have a problem with the pumps starting up, these fires occur after the pumps have been running awhile. Sometimes after a year of good service, sometimes after a week. We have been in close contact with the pump manufacturer and still do not have a resolution. We are in the process of making some modifications to the pumps, but we have not yet found the right set up.