A Mathematical Model Estimating Sea Water Discharge Time from a Hydrocarbon Storage Tank to Prevent Oil Spills

Abstract

Abstract This study is conducted to prevent the accidental petroleum product release from some onshore storage tanks into seas, in Turkey. The seawater, used to displace the liquid petroleum products from tanker ships into the onshore storage tanks, accumulates under the petroleum product in the storage tank. The field personnel, operating the gravity-controlled seawater discharge manually, may occasionally miss the discharge time and close the discharge valve too late. Hence, the petroleum product, chasing seawater in the discharge line, is accidentally released to the sea. Thus, estimating the seawater discharge time accurately is of great value for eliminating the potential coastal and offshore environmental damage, preventing the petroleum product loss, and for efficient use of personnel time. The flow behavior is modeled mathematically for the accurate estimation of total seawater discharge time. A semisteady-state flow model is developed by the integration of an unsteady-state mass balance and a steady-state energy balance. The effect of conical geometry of such tank bottoms on flow behavior is also taken into account. The differential equations of the model are solved by both analytical and numerical integration techniques. Excellent agreement of both results is obtained and compared with the field data.