Oil Removal from Tank – Still central concentric tube system and Gun-barrel tank system
Removal of Oil from a wastewater stream/Tank/Unit reduces the potential problems to the downstream equipment which occur especially in Refineries. There are three forms of oil mainly present in CETP at a refinery:
- Free Oil or floating oil is removed by either skimming the surface in the skim tank or by gravity separation.
- Emulsified Oil is comprised of oil droplets in stable suspension within the wastewater. Removal requires chemical addition to lower the pH followed by addition of dissolved oxygen or nitrogen to remove the emulsified oils as they break free from the wastewater.
- Dissolved Oil is a molecular solution within the water and can only be removed with biological treatment.
There are several factors which affect oil removal from a tank:
- In-fluent Flow rate
- Density of inlet and outlet effluent water
- Density of overflow (rich in oil)
- Height of oil separation zone
- Oil rising velocity
- Oil residence time
- Diameter of oil-droplet
- Retention time
AMNAA deals in two type of Oil removal systems
- Still central concentric tube system
- gun-barrel tank system