Horizontal Separator Working PrincipleThere are three common type of process separator:horizontal separator, vertical separator, or spherical separator. The figure above is an example ofhorizontal two phase separatorbasic diagram.The first step separation occurs at theinlet diverter, on the inlet diverter liquid and vapor will be separated as the fluid enter vessel and hits the inlet diverter that will create sudden change in momentum. The liquid droplet will fall out from the gas stream into the bottom section. Since it will take times to collect the amount of liquid, this section will provide the retention time.Retention time is needed to vapor the entrained gas in the liquid. If there are slugs in the liquid, thisretention timeprovides a surge volume to handle the slugs. The extracted liquid then flows through an outlet valve which regulated by alevel controller.The gas part will flow over the inlet diverter into the gravity settling section which located above the liquid. The gas may entrain some liquid; this liquid will be separated out by gravity in thisgravity settlingsection and it will fall down to thegas liquid interface.Before the gas leaves the vessel, it will pass through acoalescingsection. The smaller drop which cant be separated in the gravity settling section will be trapped in themist extractor. The mist extractor or coalescing section consists of vane element to remove the small droplet.The pressure inside the vessel is controlled by a pressure controller. If the pressure too high, pressure controller will give a signal to open thepressure control valveso the gas can leave from the vapor space. To maximize the gas liquid interface area, horizontal separator normally operated at half full.References:1. Surface Production Operations, Ken Arnold and Maurice Stewart

CFD Simulation of Three-Phase Separator: Effects of Size DistributionN. Kharoua,L. KhezzarandH. SaadawiASME Proceedings | 13th International Symposium on Gas-Liquid Two-Phase FlowsabstractThe gas/oil/water separation in a three-phase horizontal separator, employed by the ADCO company in Abu Dhabi, was studied previously using the Eulerian-Eulerian with the k- model assuming mono-dispersed secondary phases (oil and water). The separator was equipped with new internals due to the increasing amounts of water and Gas-to-Oil Ratio GOR from the field. The approach allowed the description of several features of the internal flow but the prediction of the overall efficiency was largely overestimated compared to the measured value from the field. The source of the discrepancy could be traced back to the assumption of mono-dispersed secondary phases and possibly to the unknown structure of the size distribution at the inlet of the separator preventing thus a correct modeling of drag between the phases and, hence, influencing momentum and secondary phases (oil and water) dispersion. Investigations, using the Population Balance Model, for size distribution, were conducted. Normal and Skewed distributions were employed to represent, only, the secondary water phase due to the limitation of the population model used to only one secondary phase. The paper presents, in addition to the separation efficiency, the internal multiphase flow behavior in terms of overall and local phase distributions. The simulations with PBM model showed a clear improvement of the results in terms of separation efficiency compared with field tests although no experimental data related to the size distribution were available.Copyright 2013 by ASME