FRIESS Oil Skimmer in the steel industry

In order to clean the cooling water in steel factories companies usually use a combination of scale pit, longitudinal clarifier and gravel filter.

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Scale pit in the steel industry

Compared to water the specific weight of scale is much higher. For this reason the scale particles will settle on the bottom of the scale pit and the longitudinal clarifier. The scale, collected on the bottom of the scale pit, will be removed by an excavator. The scale, which settles on the bottom of the longitudinal clarifier, will be collected in the deep part of the basin with the help of a scraper. From time to time the collected scale will be removed by an excavator.

Longitudinal clarifier with scraper in a steel factory

The specific weight of oil and grease is lower than the specific weight of water. For this reason oil and grease will settle on the surface of the water. The most part of the oil will settle on the longitudinal clarifier. The flow of the water in the longitudinal clarifier will drive the floating oil and fat to the outlet of the basin. The floating oil and grease will be stopped by a downflow baffle. The water floats underneath the downflow baffle into the pump chamber. From there the water will be pumped into the gravel filter and back into the factory. On the water surface in the longitudinal clarifier grease, lubrication oil, hydraulic oil and other hydrocarbons mixed with scale and particles, float on the water. It is extremely necessary to remove the floating hydrocarbons. Otherwise oil and grease will accumulate in the gravel filter and finally will block the gravel filter.

The easiest way to remove the floating oil and grease is an adjustable channel.

Adjustable channel in a longitudinal clarifier

The inlet edge of the channel must have the same height as the water surface. Continuously water with oil will flow into the channel and is removed out of the cooling water separation. The big disadvantage of this method is that the adjustable channel will remove typically 1 % – 2 % of oil mixed with 98 % – 99 % water. The mixture of oil and water has to be separated in an additional decanter. In order to remove the floating oil and grease easily and efficient we recommend to use the oil skimmer model S 100 with oil collector tube and small decanter.

Adjustable channel in a longitudinal clarifier

The inlet edge of the channel must have the same height as the water surface. Continuously water with oil will flow into the channel and is removed out of the cooling water separation. The big disadvantage of this method is that the adjustable channel will remove typically 1 % – 2 % of oil mixed with 98 % – 99 % water. The mixture of oil and water has to be separated in an additional decanter. In order to remove the floating oil and grease easily and efficient we recommend to use the oil skimmer model S 100 with oil collector tube and small decanter tank.

Oil skimmer S 100 at longitudinal clarifier

The oil skimmer will be mounted at the end of the longitudinal clarifier near the pump chamber. The oil collector tube floats on the water and will be guided parallel to the downflow baffle. The oil collector tube works along the whole width of the basin. The oil and grease, which has been picked up by the oil collector tube, floats from the scraper in the oil skimmer into sludge trap underneath the oil skimmer.

Oil collector tube with tube guide and Oil collector tube floats parallel to downflow

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