Recovery and recirculation of 70 % of the quench oil is considered an exceptionally high level of efficiency according to Mr. James Reh, Plant Engineer for Lindberg Heat Treating Company, Rockford Division. He reported that the oil skimmers have become a vital step in the company's energy conservation program for recovery of oil previously discarded.
'In addition to saving more than 2/3 of the quench oil cost,' Mr. Reb said, 'Lindberg has saved countless hours of downtime formerly required to clean out their washer tanks every week. The tanks now run continuously for several months without requiring any maintenance.' The Lindberg plant in Rock-ford, Illinois, has 8 oil skimmers in operation on washer tanks. Their Norwood, Massachusetts, plant uses 3 and there is one oil skimmer each at Lindberg's plants in West Allis, Wisconsin, and Minneapolis, Minnesota. All of the oil skimmers are equipped with 8' corrosion-resistant belts that remove up to 32 gal of quench oil per hour each.
Operation of the oil skimmer is based on the principle that oil is attracted to and will adhere to metal better than water. The skimmer's endless metal belt draws the oily wastes up out of the liquid being cleaned, over the head pulley and past doctor blades which remove the oily residue from both sides of the belt. The oil drains into a trough from which it flows to a collecting tank or drum.
A vital part of the oil skimmer operation is the ability of the head pulley to drive the belt without interfering with oily residue on both sides of the belt. A free-riding tail pulley stabilizes belt operation but permits it to bend around floating obstructions that might damage permanently secured equipment.
Capacities of the oil skimmer range from 32 to 160 gal of oily wastes removed per hour, depending on the number of 8' belts on the unit. Because the endless belt is available in almost any length and the tail pulley is free riding, the skimmer can he furnished to accommodate any height requirement, depending on the depth of the liquid to be cleaned and the distance the oily residue is to be raised.
The oil skimmer also is available in a heated model for use in external applications or anywhere low temperatures tend to solidify oily wastes, in any application involving removal of oil, grease, or fat which tends to solidify at ambient temperatures. Units are also available with belts of special materials to withstand high alkaline or high acid solutions (pH 1 - pH 14).