Pre-TEG coalescer

In case the quantity of water and oil coming to the coalescer is small, the control systems are designed for a gap control. Gap control means the control valve will open at some high liquid level and will close at some low level in the chamber. 

The contactor is designed as a reflux absorber where the wet gas is flowed from bottom to top and the reflux (lean glycol) flows from top to bottom. 

Process engineering and design using Visual Basic 

There is no specific reboiler or condenser attached with the column. Lean glycol absorbs the moisture from the wet gas stream making the gas stream dry, and the glycol leaving the column containing water becomes rich glycol. 

Bubble cap trays are commonly used as column internals with a trend to change the internals to structured packing. Use of structured packing reduces the column diameter substantially and, hence, is more economical. 

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Generally, one glycol filter and one activated carbon filter are installed in series on the rich-glycol line from the flash separator. These filters are required to remove inert particles from the system as well as some oil mist that escapes the pre-TEG coalescer. 

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