Q. Explain about water De-Oiling process?

The De-Oiling process consists of three major components:

• The Surge and Skim Tank which reduces PW oil content to 100 ppm
• IGF unit which reduces oil content to 10 ppm
• ORF which reduces oil content to less than 2 ppm

The inlet stream to the Surge Tank can be dosed with de-oiling polymer to assist with emulsion breaking. PW flows from the Surge Tank by gravity. Entrained oil accumulates and floats as a top liquid layer in the Surge Tank. The Surge Tank is connected to the VRU gathering system to collect the vapours that will normally evolve from the water as the pressure is reduced on the inlet to the tank.

The Skim Tank accepts PW from Surge Tank. The function of this tank is to reduce oil content from 1000 ppm to 100 ppm. Oil skimming is carried out intermittently from the compartment. Skim Tank is also connected to the VRU gathering system.

The function of IGF package is to reduce oil content from 100 to 10 ppm. The IGF technology uses a combination of chemical and gas bubbles to accelerate oil-water separation. De-oiling polymer can be injected into the stream of the package to facilitate the agglomeration of the froth. Gas is induced hydraulically, driven by Eductor Pumps.

Water from the IGF De-Oiled water compartment is pumped to the ORF Package for the final De-Oiling Stage. The ORF package reduces the oil content further to less than 2ppm. The De-oiled PW is collected in the De-Oiled Water Tank for storage before further processing in the Water Treatment Plant.