Chapter 4 - Equipment sizing

Abstract

The chapter discusses the design of horizontal and vertical separators, and the sizing of partly-filled horizontal and cylindrical vessels. Vessels used for processing in the chemical process industries (CPI) are principally of two kinds: vessels without internals and vessels with internals. Empty separators are the drums that provide intermediate storage or surge of a process stream for a limited or extended period. Vertical liquid-vapor separators are used to disengage liquid from vapor when the volume of liquid is less as compared to that of vapor. The maximum allowable vapor velocity in a vertical separator that reduces the liquid carryover is dependent on liquid and vapor densities, droplet size, and physical characteristics of the system. Horizontal vessels are used for substantial vapor-liquid separation where the liquid holdup space must be large. Maximum vapor velocity and minimum vapor space are determined in a vertical drum. The chapter also highlights the sizing of a cyclone and a solid-desiccant gas dryer. Cyclones are widely used for the separation and recovery of industrial dusts from air or process gases. Cyclones are the principal type of gas-solids separators using centrifugal force. The use of solid desiccant is limited to applications with very low water dewpoint requirements, simultaneous control of water and hydrocarbon dewpoints, and sour gases.