Steam at 35 psig has a saturation temperature of 260 deg F, which is near the lower solidification temperature for sulfur. Therefore, introducing a steam quench between the faces and the segmented carbon bushing at this pressure and temperature and controlling it with a needle valve on the flange drain line would:
- Equalize the temperature around the faces to create a better environment for the sulfur in the seal gap, resulting in a more even transfer of the seal-generated heat away from the faces to keep the temperature in the gap below the upper solidification temperature
- Improve the heat transfer capability of the seal, since steam conducts heat better than air, which is an insulator
- Prevent the sulfur from reaching the lower solidification temperature as it leaks across the faces
- Move the sulfur leakage away from the ID of the faces to prevent it from accumulating, solidifying and hanging up the faces
Sealing the Deal
To install this solution, the refinery had to make a few design modifications to its process line. Engineers from the refinery and the seal company teamed up to minimize equipment modifications. The seal company's engineers made recommendations both for the equipment design and for implementing environmental controls.
“Teamwork made this a successful outcome,” said Batinick. “We were present for the seal installation and start-up, and we provided training and support. There should be no issues with the seal based on operators following the revised recommendations and procedures from plant engineering and the seal manufacturer.”
Within two weeks after the pump start-up—the time when sulfur would start to accumulate around the pump—no sulfur leakage was detected. Housekeeping is now a non-issue for the refinery and although it has had other pump issues, none were related to the seal. The refinery is pleased this solution and is currently in the process of modifying a second pump to accommodate the pusher seal and is considering retrofitting several other pumps within the facility.
Pumps, & Systems, September 2010