Direct heat and mass transfer in structured packings

Abstract

Direct heat transfer is an important method in the exchange of heat between two countercurrent process streams within a column. The process can be simulated using either the theoretical stage or the rate based concept. With both concepts, a reliable heat transfer coefficient is needed. Additionally, the rate of the heat transfer coefficient is influenced by the simultaneous mass transfer. A number of application-dependent methods to estimate the heat transfer coefficient have been developed, mainly for random packings. It is the purpose of this paper to extend this work to structured packings. A number of experiments with air/water have been performed in a column of 300 mm inner diameter with Mellapak 250.Y, 250.X and 125.X at ambient conditions. A second group of measurements were done using an oil/air system where only sensible heat was transferred. Based on these experimental results a method was developed to predict the heat transfer coefficient for structured packings. The method is applied to examples of industrial importance, like a gas quench, a gas saturator and a pump-around zone in an atmospheric tower.