For offshore facilities a vertical vessel is typically recommended for the following reasons:
- Typically the rate of liquid accumulation is small, and a vertical separator can provide adequate liquid surge volume in the bottom of the vessel.
- Smaller footprint.
- Easier to clean and maintain.
- A vertical vessel can accommodate a tangential entry nozzle, which promotes removal of entrained liquid from the vapor.
- Compressor Suction Scrubbers typically have been equipped with wire mesh mist eliminators, which require vertical upflow of gas. For this a vertical vessel accommodates horizontal installation of the wire mesh pad.
A horizontal vessel is preferred due to reasons below:
- Takes less vertical space, which may be important in some offshore installations.
- Better liquid slugs handling than horizontal vessels.
- Vane-type mist eliminator is better accommodated.