The function of the grease trap is to separate and remove floatable oil substances in oily wastewater by natural floating method. The oil separation tank can remove the oil substances in the floating and coarse dispersion state with the density less than 1.1, but it has little effect on the oil in the emulsified, dissolved and dispersed state.

Its basic requirements are as follows:

(1) The grease trap must have both oil collection and sludge discharge measures.

(2) The oil separation tank should be sealed or provided with a movable cover plate to prevent oil and gas from polluting the environment and fire accidents, and at the same time, it can play the role of rain protection and heat preservation.

(3) Effective insulation and cold-proof measures should be taken for oil separation tanks in cold areas to prevent dirty oil from solidifying. In order to ensure the smooth flow of dirty oil, a heater with steam as the heat source can be set under the oil collecting pipe and dirty oil conveying pipe.

(4) A certain range around the oil separation tank should be identified as a fire-forbidden area, and sufficient fire-fighting equipment and other fire-fighting means should be provided. Steam is generally used for fire prevention in the oil separation tank, and a circle of steam fire-fighting pipeline is usually set along the tank wall 211mm below the tank top.

(5) There should be steam pipe joints near the oil separation tank, so as to connect temporary steam to put out the fire, or clean the pipeline or dirty oil when the pipeline is blocked due to the solidification of dirty oil in winter or the tank wall is stuck with dirty oil.

Extended information

Generally, the oil collecting device of the oil separation tank adopts the following four forms:

(1) Fixed oil collecting pipe collects oil. The fixed oil collecting pipe is located near the outlet of the oil separation tank, and the elevation of its center line is generally 61mm below the design water level, and the height from the tank top is more than 511 mm.

The fixed oil collecting pipe is generally made of steel pipe with a diameter of 311mm, and the worm wheel and worm are used as the transmission system, which can rotate clockwise or counterclockwise, but the rotation range should not exceed 41.

the arc length of the oil collecting opening of the oil collecting pipe is the arc length corresponding to 61 of the cross section of the oil collecting pipe. At ordinary times, the cut is upward. When the oil slick reaches a certain thickness, the oil collecting pipe rotates around the axis, so that the cut is immersed under the floating oil layer on the water surface, and then the oil slick overflows into the oil collecting pipe and flows to the oil collecting pool along the oil collecting pipe. Small grease traps usually collect oil in this way.

(2) mobile oil collection device collects oil. When the oil separation tank has a large area and there is no oil scraping facility, the oil can be collected flexibly by using the mobile oil collecting device according to the floating and distribution of the floating oil, and the elevation of the oil outlet weir of the mobile oil collecting device can be adjusted at any time according to the specific situation.

the mobile oil collecting device runs in water with hydrophobic and oleophilic oil absorbing belt. After the floating oil is brought out of the water, it enters the squeezing plate of the mobile oil collecting device to squeeze the oil into the oil collecting tank, and the oil absorbing belt then enters the pool to absorb the floating oil.

(3) Automatic oil collection hood collects oil. When there is no oil collecting pipe in the separation section of the oil separation tank or the oil collecting pipe is not effective, an automatic oil collecting cover can be installed to collect oil. The elevation of oil outlet weir and the installation position of automatic oil collection cover should be considered comprehensively according to the nature of recovered oil and the requirements for its moisture content.

(4) oil scraper scrapes oil. Large oil separation tanks usually use oil scraper to scrape the floating oil to the oil collecting pipe. The form of oil scraper is the same as that of slag scraper in air flotation tank, and sometimes it is combined with mud scraper to become an oil scraper.

The oil scraper and sludge scraper of the horizontal separation tank are arranged in the separation section, and the oil scraper and sludge scraper scrape the floating oil and sludge to the water outlet end and the water inlet end respectively, so it is necessary to install the whole tank. The inclined plate oil separation tank is only equipped with an oil scraper in the separation section, and its mud discharge generally adopts bucket gravity mud discharge.