Coalescers are used wherever tiny droplets of one fluid are carried in another. They work by gathering fine droplets into larger ones, which then separate from the main stream by gravity. The two main types are liquid-liquid coalescers and gas-liquid coalescers, and the difference comes down to what is being carried and what it is carried in.
How a coalescer works
Fine droplets, often too small to settle on their own, are captured on the fibres of the coalescing element. They merge into larger drops, move through the element, and then fall or drain away from the main stream. The cleaner stream continues downstream and the collected liquid is drained from the vessel.
Gas-liquid coalescers
A gas-liquid coalescer removes liquid droplets and aerosols from a gas stream. The gas is the main stream and the liquid is the contaminant.
- Protecting compressors and downstream equipment from carried-over liquid
- Cleaning the feed gas before an amine contactor, and reducing liquid carryover from amine and other process gas streams
- Gas phase filtration where liquid mist would otherwise damage equipment or contaminate the process
Liquid-liquid coalescers
A liquid-liquid coalescer separates one liquid dispersed in another, for example fine hydrocarbon droplets in water or in an amine solution. It is paired with a phase separator, where the merged drops settle out.
- Removing free hydrocarbons from amine, glycol or water streams
- Separating oil and water in recycle and effluent streams
- Cleaning up spent caustic and other process liquids
Side by side
| Gas-liquid coalescer | Liquid-liquid coalescer | |
|---|---|---|
| Main stream | Gas | Liquid |
| What it removes | Liquid droplets and aerosols | A second liquid dispersed in the first |
| Typical use | Compressor gas, amine feed gas | Amine, glycol, water and caustic streams |
| Usually paired with | A vessel with drain | A phase separator |
What you need to tell a supplier
- The fluid or gas, its flow rate, pressure and temperature
- What the contaminant is and roughly how much of it there is
- Whether you are fitting a new system or replacing elements in an existing vessel
For how coalescers fit into an amine unit, read what causes amine foaming and how filtration helps.
Coalescers from Power Energy Gulf
Power Energy Gulf provides liquid-liquid and gas-liquid coalescers, phase separators, filters and filter skids, and can retrofit existing vessels. See our amine system filtration and gas phase coalescers page, or send us your flow rate, pressure and contaminant for a recommendation.