The liquid / liquid separation process is gravity driven and as a result, additional separation aids are sometimes required to ensure that sufficient water is removed from the oil and vice versa. In many designs of 3-phase (or 2-phase liquid / liquid), horizontal or vertical separator, a Plate Pack Coalescer is inserted to achieve higher efficiencies of liquid / liquid separation.

Plate Pack Coalescers contain numerous parallel plates at a fixed angle, the angle being dependant on the application, the duty, the process fluids and whether solids are present etc and have two main benefits; the flow through the narrowly spaced plates stays in the laminar regime much longer, therefore smaller droplets can be separated and as the distance the dispersed phases have to travel to the interface is much smaller; the residences times required for the separation process and consequently the vessel size can be smaller to obtain similar efficiencies than with gravity-settling only.

It is clear that one of the most important parameters that determine the effectiveness of this separation technique is the rising (for oil in water) or settling (for water in oil) velocities of the dispersed droplets, thus the length of the plates and the flow velocity between the plates determine the time the droplet has to carry out its traverse.

•  The diameter of the separator vessel can be substantially reduced, leading to reduced vessel wall thickness, weight and capital expenditure (CAPEX).
• Separation efficiencies >99% for droplets of 30-50 μm and larger.
• Efficient and continuous separation of solids can be achieved.
• Enhances interface level control.
• Modular or framed assembly.
• Wide Operational Range – 100% turndown.
• Allows a greater fluid throughput for a set vessel size, in a revamp project.
• Less likely to foul than mesh / structured packing /coalescing media.
• No moving parts thus no maintenance.

Applications:

• Separators.
• Skimmer Vessels.
• Enhanced oil recovery systems.