Improved Mechanical Seal For High Pressure Pumps In Severe Abrasive Tailings Services
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The cost of high pressure gland water and increasing environmental concerns have made the use of flushless mechanical seals attractive in many slurry applications. One such application exists at Syncrude Canada Lts (SCL). SCL is a large scale mining operation that extracts crude oil from tar sand. The by product of the process, 150 degrees F sand and water tailings, is pumped to remove storage sites. Tailings pumps are staged in series to reduce the number of pump stations. As a result, tailing line pressures can reach 300 psig. Recently, SCL expanded their tailings storage by adding a new remote site. Due to the high cost of installing and maintaining a gland water line, the decision was made to use flushless mechanical seals in place of packing. At the time of the expansion a large slurry seal capable of handling the high pressure tailings was not available; however, one seal manufacturer had a prototype seal design that had potential. This seal was chosen with the thought that it could be developed and refined to provide consistent 200 hr life. Having made the decision to use mechanical seals, the pipeline system was designed with the mechanical seal requirements in mind. Shortly after startup of the new tailing lines, seals began to fail. With the line now in operation, it was necessary to quickly resolve the problems. An intensive effort was launched to determine why seals were failing. Initial investigation showed the process, controls, and new equipment were working properly. The failures appeared to be seal relation. Over the next months, joint work conducted by SCL and the seal manufacturer identified a range of seal problems and interim measures were implemented to increase seal life. As a result of this work, an improved seal design was achieved. Extensive lab and field testing of the improved seal has proved its performance in this aggressive service. Active seals now average 3000 hr, with some seals having a life of over 6000 hr.
Manning, Frank E.; Mosher, Rod; McCullough, Doug (1996). Improved Mechanical Seal For High Pressure Pumps In Severe Abrasive Tailings Services. Texas A&M University. Turbomachinery Laboratories. Available electronically from