Liquid-liquid coalescing
Separation of two or more immiscible liquid phases is critical in the production of a wide range of products. From the moment the feed streams are introduced into the process and continuing through the reaction and purification steps, liquid-liquid coalescing often plays an important role. 

Overhead drums
Refinery fractionator overhead drums frequently become a bottleneck when the towers they service are fitted with higher capacity internals. The higher throughput rates increase the separation demands on the overhead drum. Poor liquid-liquid separation in the drum creates high water level in the reflux streams that can lead to corrosion on the trays and increased energy consumption. The installation of liquid-liquid coalescing internals in the drum can alleviate these problems.
 
Alkylation units
Alkylation units in refineries have several steps where sulfuric acid, caustic, and water are mixed with the hydrocarbon streams and then separated. Liquid-liquid coalescers help to keep the separations as sharp and clean as possible to minimize both reagent usage and downstream corrosion and fouling.
 
LPG caustic and amine treaters
LPG caustic and amine treaters use coalescers to reduce entrainment down to ppm levels in the LPG stream leaving the top of the tower. This minimizes chemical consumption and downstream contamination.