By Jung Seob Kim, Taek-kyoung Oh, Heather Jean Dunsheath |
The pipe-flow equation presented here can be used to properly and easily size pipelines for liquid, vapor and two-phase flow. Example calculations are also shown
Sizing pipelines is a fundamental task for design engineers, who typically use several equations to size pipes for different flows (liquid/vapor/two-phase). The flow equations, however, are basically analogous. Incompressible flow calculations are considered relatively simple and easy to do. However, a major challenge faced by design engineers is sizing a pipe flow that experiences significant variations in the flow density and velocity.
Generally, calculations for vapor or two-phase piping often involve repetitive calculations for accurate results. Sizing a pressure-relief system that operates at very high velocity and high pressure drop is a difficult application. Vapor flow and two-phase flow in relief-discharge piping involve rapid changes in density that result in very high line velocities. The calculation methods of the American Petroleum Institute (API) have been widely used in industries for sizing relief system piping . For vapor flow, the relatively conservative isothermal equation is recommended. And if the pipe system handles vapor and flashing or non-flashing…