The technology of oil water separator system
The definition of water that is suitable to be discharged should contain less than 15 parts per million of oil. Most oil water separators that use the gravity system can only achieve 100 parts per million which requires that is must be used in conjunction with a filter system. A complete oil water separator system must first be filled with clean water then the oil water mixture is pumped through the separator inlet pipe into the coarse separating compartment. Oil due to its lower density will separate and rise into the oil collection space. The remaining oil and water mixture will then flow down into a fine separating compartment and move slowly between the catch plates.
More oil will separate into the undersides of the catch plates and travel outwards until it is free to rise into the oil collecting space. Water which is almost oil-free will pass into a central pipe and will leave the separator unit. At this point the purity will be 100 parts per million or less. An automatically controlled valve will release the separated oil into a storage tank while air is being released from the unit into a vent valve. Steam or electric heating coils are provided in the upper or lower parts of the separator according to the type of oil that has to be separated. In cases when greater purity is required, the almost oil-free water will pass through a filtering unit.
The filtering stage of the oil water separator system
In the filtering stage of the oil water separator system, water will flow through two filter stages where oil will be removed as it passes through the oil collecting spaces. At the first stage filter, physical impurities will be removed so that fine separation can be promoted. At the second stage filter, coalesce inserts are used to achieve the final de-oiling. Coalescence means the breakdown of surface tension between oil droplets in the oil and water mixture which results in joining to increase its size. Oil from the collecting spaces will be drained away manually as required or once a week. The filter inserts will require changing based on the operating conditions and the expiration of its useful life. Current regulations also require the use of a monitoring unit that will continuously record and give an alarm when the levels of discharge are in excess of 15 parts per million.