Modeling Membrane Gas and Vapor Separation in the Aspen Plus Environment

The paper presents the results of the development of a unit for calculating mass transport in a membrane gas separation apparatus in the Aspen Plus environment. The created user model has been verified by comparing the results of the calculation of separation characteristics with available experimental data for two cases. In the first case, the calculation results were compared with experimental data on the separation of the ternary H2O/EtOH/N2 (13.3/5.5/81.2 mol %) vapor–gas mixture simulating the stream from the stripping column of a laboratory membrane vapor separation unit with a plate-and-frame membrane module for ethanol recovery from fermentation broth. It has been shown that the calculated concentrations of the components in the retentate and permeate streams are close to the experimental values obtained in the separation of the ternary vapor–gas mixture. In the second case, the calculation results were compared with experimental data obtained upon the separation of a binary N2/CH4 gas mixture (99/1 mol %) simulating a stream with a low content of an easily penetrating impurity component using a radial membrane module. It has been found that the calculated concentration of CH4 in the retentate is noticeably less than in the experiment, especially at high stage cuts, a difference that is associated with the increasing influence of the longitudinal mixing of components at low speeds of the mixture in the channels of the membrane module, which deteriorates the separation characteristics of the apparatus with respect to the removal of impurities and requires additional consideration of the deviation from the plug-flow mode in computational mathematical models used for this case.