OHMSETT TESTS OF THE TOSCON WEIR SKIMMER AND GRAVITY DIFFERENTIAL SEPARATOR1

Abstract

ABSTRACT An evaluation of the effectiveness of the Texas Oil Spill Control, Inc. (TOSCON) weir skimmer and gravity differential separator was conducted at the U.S. Environmental Protection Agency's Oil and Hazardous Materials Simulated Environmental Test Tank (OHMSETT) facility in October 1982. The tests were sponsored by the OHMSETT Interagency Technical Committee (OITC). The TOSCON skimmer and separator are designed and manufactured by Texas Oil Spill Control, Inc., of Conroe, Texas. The skimmer was designed to operate at intake rates up to 227 cubic meters per hour (m3/h) alone and up to 11.4 m3/h when operated with the oil-water separator. Recovery efficiency and oil recovery rate were the criteria used to measure the skimmer's performance with respect to oil slick thickness, propeller speed, waves, and tow speed. Separator performance was judged by its effectiveness in separating an oil and water dispersion with respect to percent water in the oil effluent and oil concentration in the water effluent samples. The independent variables used in testing the separator were flow rate and oil concentration of the influent liquid. The separator achieved a best performance effluent oil sample containing less than 0.02 percent water. Samples taken during normal operating conditions contained an average of 2.2 percent water. The lowest concentration of oil in an effluent water sample was 65 milligrams per liter (mg/L); the average concentration for all samples was 506 mg/L of oil. Overall, the separator performed best when oil concentrations in the influent were above 40 percent. The skimmer was tested in oil slicks from 1 millimeter (mm) to 31 mm thick. Oil recovery rates ranged from 0.5 to 8.6 m3/h; the average was 2.5 m3/h. Recovery efficiency ranged from 8 to 59 percent. Best performance of the skimmer and separator when tested as a system occurred when the skimmer propeller was run at a speed of 620 rpm in a light oil slick of 26 mm. Under these conditions, the separator yielded effluent oil with 0.2 percent water content and effluent water containing 192 mg of oil/L.