Small amounts of oil and very viscous grease come from the lubrication of the roll bearings. Hydraulic systems leak small but continual amounts of hydraulic oil into the cooling water system. Burst hoses or damaged piping systems caused by accidents can instantly release up to 1,000 liters of hydraulic oil into the cooling water system.
This oil and grease also mixes with the metal scale, dust, and other particles. A lamella separator allows the heavy solid particles to sink to the bottom, while the oil and grease that has become mixed with solid materials, form a thick sticky mass that floats on the water surface of the separator tank. The oil / grease mixtures cover the whole 6 m X 4 m surface of the lamella separator tank. A baffle contains the oil / grease mixtures, while the water can return to the cooling water system.
The water, before flowing back into the cooling water system, passes through a sand / gravel water clarification filter bed. All the oil, grease and the sticky mass has to be reliably removed otherwise the sand and gravel of the clarification filter will become contaminated with these products which, in time, causes the filter bed to become clogged and it then no longer functions. The cost for removing and disposing the oil-contaminated sand and gravel of the clarification filter are extremely high, so the main objective is to keep any possible oil contamination of the filter bed as small as possible. If the oil and grease floating in the separator is not frequently removed, some of it may pass under the baffle, carried along by the water flow and end up in the gravel filter