A double-barrel horizontal separator is a variation of the horizontal separator Figure 2-11. Double-barrel horizontal separators are commonly used in applications where there are high gas flow rates and where there is a possibility of large liquid slugs, e.g., slug catchers.
Single-barrel horizontal separators can handle large gas flow rates but offer poor liquid surge capabilities. The double-barrel horizontal separator partially alleviates this shortcoming. In these designs the gas and liquid chambers are separated as shown in Figure 2-11. The flow stream enters the vessel in the upper barrel and strikes the inlet diverter. The gas flows through the gravity settling section, where it may encounters a baffle type mist extractors, or directly to the wire mish mist extractor to en route to the gas outlet.
The baffles help the free liquids to fall to the lower barrel through flow pipes. The liquids drain through a flow pipe or equalizing tube into the lower barrel. Small amounts of gas entrained in the liquid are liberated in the liquid collection barrel and flow up through the flow pipes or equalizing tubes. In this manner the liquid accumulation is separated from the gas stream so that there is no chance of high gas velocities re-entraining liquid as it flows over the interface. Because of their additional cost, and the absence of problems with single-vessel separators, they are not widely used in oil field systems. However, in gas handling, conditioning, and processing systems, two-barrel separators are typically used as gas scrubbers on the inlet of compressors, glycol contact towers, and gas treating systems where the liquid flow rate is extremely low relative to the gas flow rate.
