John T Small

Optimal Process Design of 2- and 3-Phase Horizontal Production Separators for Oil and Gas Installations John T Small

This book details a Microsoft Excel spreadsheet which models numerically the following key design factors for horizontal separators and optimizes the vessel dimensions using the Solver add-in, allowing the engineer to minimize the size of the vessel and associated piping whilst achieving satisfactory performance in the separation, process control and safeguarding functions: -Gravity settling zone dimensions for successful phase separation. Opposing schools of thought favor computation via droplet settling theory versus liquid retention times.-Provision of adequate liquid hold up times and height differences between contiguous level control and trip settings.-Type of inlet device, and its impact upon the size of inlet pipework and the dimensions of the separator vessel.-Nozzle sizing according to erosional, velocity head and velocity criteria, and the impact on vessel dimensions.-Maintaining axial velocities of oil and water phases within acceptable limits.-Prevention of re-entrainment of oil droplets into the gas phase.-Prevention of transient gas blowby or gross carryover of liquid during unplanned shutdown.-Provision of adequate liquid and gas holdup volumes for slugging and surging.-Prevention of spurious trips due to foaming, where applicable. The principal calculation method for dimensioning the gravity settling zone of the vessel is based on settling theory, according to which droplets / bubbles of certain diameters settle to their respective continuous phases, however the spreadsheet allows the engineer to concurrently specify minimum allowable oil and / or water retention times if desired.