Solving Oil Water Separator Problems

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Kirby S. Mohr, P.E.
Mohr Separations Research, Inc.
Lewisville, TX 75077

Michael Foley, CQE, P.E.E.

Imperial Oil Company
Sarnia, Ontario, Canada

John N. Veenstra, Ph.D., P.E.

Oklahoma State University
Stillwater, OK, USA

A paper presented at the International Petroleum Environment Conference in Houston, Texas, 1999


Many refineries utilize “once-through” cooling systems using river or lake water as the fluid for cooling process streams. This is an efficient means of cooling but can be a water contamination source if any of the heat exchangers leak. A “once-through” system at a refinery was studied to explore the possibility of upgrading equipment to ensure the capture of any oil in the refinery effluent in the event of a leak in a heat exchanger.

A refinery has many products that could leak into the cooling water and the magnitude of potential leaks varies widely. The water temperature varies also with weather conditions.

A design utilizing more efficient internals (multiple angle coalescing plates) for the pits would be expected to reduce the impact of releases, and further improve effluent water quality. Wide variations in possible water oil content, temperature, and oil specific gravity made design of an efficient system difficult. For this reason, a statistical approach was taken in the design. This paper provides information on a current refinery situation, variations in the flow, oil content, etc., as well as the methods used to estimate the probabilities of meeting effluent requirements under spill conditions with various quantities of coalescing plate media.