They are commonly applied in the global oil and gas industries for the removal of water or hydrocarbon condensate.
All liquids will be removed but lube oil recovery is the primary reason for installing a coalescer on the outlet of a compressor.
They have been also used in pyrolysis gasoline (benzene) removal from quench water in ethylene plants, although in this application, the constant changing of cartridges can lead to operator exposure to BTX (benzene, toluene and xylene), as well as disposal issues and high operating costs from frequent replacement.
The squared dependence of droplet diameter in Stokes' law, increase the settling speed and destabilizes the emulsion.
The emulsions are destabilized using gravitational separators, and the settling rates are increased by applying heat, demulsifiers, and AC electric fields.
The AC electric field gives rise to attractive forces between water droplets and increases the probability of coalescence at contact.
By keeping the treatment and settling sections separate, a compact electrostatic coalescer can be obtained that can also be retrofitted.
Liquid-liquid coalescers are also widely used in the oil refining industry to remove the last traces of contaminants like amine or caustic from intermediate products in oil refineries, and also for the last stage dewatering of final products like kerosene (jet fuel), LPG, gasoline and diesel to less than 15 mW free water in the hydrocarbon phase.