How do you design a vapor-liquid separator?

Separator design: (1) Define inlet conditions - flow rates, compositions, pressure, temperature. (2) Flash calculation to determine L/V split. (3) Vapor disengagement - size for droplet settling using Souders-Brown correlation: V_max = K x sqrt((rho_L - rho_V)/rho_V). K depends on demister type and pressure. (4) Liquid residence time - typically 2-5 minutes for process control, longer for three-phase. (5) Surge volume - based on upset duration. (6) Select orientation - vertical for high L/V ratio, horizontal for low L/V or three-phase. (7) Set level ranges - LLLL, LLL, NLL, HLL, HHLL with appropriate spans. (8) Size nozzles for inlet momentum and outlet velocity limits. Add internals as needed (inlet device, demister, vortex breaker).