Liquid Coalescer Separator and Filter

The main aim of using a Coalescer is to separate two different fluids or liquids based on density differences. It is widely used in the wastewater treatment plant for the oil and gas industry whereby heavy amount of oil residue is expected mixed with the water discharge. The are different types of coalescer designs with each having different degree of separation based on its mode of operation. For instance, one such popular design is the cyclone system, which is commonly employed in the oil and gas industry. The principle behind the separation is the use of cyclone effect to separate two phase of liquid whereby with the cyclonic action, oil will form a larger droplet size.

Commercially available coalescers introduced by different manufacturers comes with a certain performance efficiency that largely depends on how well the system is designed to ensure droplets were well-formed. The inlet chamber of a typical deoiling vessel that forms the coalescer system is usually sized up to generate buffer retention time for the wastewater to retain in it for at least 20 seconds. Certain systems make use of low-intensity pre-coalescing vanes to further extend the retention time so that maximum efficiency can be achieved. Normally, wastewater will then be diverted to a sediment chamber, which allows those heavy solids to separate out.

The chamber design usually has parallel corrugated plate coalescer and as water passes through, the collected oil will coalescence into sheets collected on the underside of each plates. The buildup material will eventually float to the surface where all the oil will accumulate there. Clean water effluent will flow downwards and thus will be drained out from the system. Other proprietary designs introduced by different suppliers will focus on improved efficiency such as using a polypropylene coalescer, which works something like a filter to intercept oil droplets. For better control of the whole system, additional instrumentation such as high level sensors together with temperature probe can be fixed and incorporated to create a high efficiency unit.

Related topics on Physical Treatment Processes:
Dissolved Air Flotation System
Grit Chambers

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