Horizontal Separators :

Horizontal separators are most efficient where large volumes of total fluids and large amounts of dissolved gas are present with the liquid. The greater liquid surface area in this configuration provides optimum conditions for releasing entrapped gas. In the horizontal separator,the liquid which has been separated from the gas moves along the bottom of the vessel to the liquid outlet. The gas and liquid occupy their proportionate shares of shell cross-section. Increased slug capacity is obtained through shortened retention time and increased liquid level.Fig also illustrates the separation of two liquid phases (glycol and hydrocarbon). The denser glycol settles to the bottom and is withdrawn through the "boot." The glycol level is controlled by a conventional level control instrument. In a double barrel separator, the liquids fall through connecting flow pipes into the external liquid reservoir below. Slightly smaller vessels may be possible with the double barrel horizontal separator where surge capacity establishes the size of the lower liquid collection chamber.
As an example of a horizontal separator consider a rich amine flash tank. In this service:
· There is relatively large liquid surge volume leading to longer retention time (this allows more complete release of the dissolved gas and, if necessary, surge volume for the circulating system).
· There is more surface area per liquid volume to aid in more complete degassing.
· The horizontal configuration would handle a foaming liquid better than a vertical.
· The liquid level responds slowly to changes in liquid inventory.