Steady State Numerical Simulation of Natural Gas Cleaning Process

Abstract

Natural gas is a promising elective source of methane (CH4) due to its accessibility and renewability. However, unfortunately, a high rate of carbon dioxide (CO2) and very little hydrogen sulfide (H2S) is found in this CH4 source. These compounds must be removed to get natural gas of satisfactory quality. One of the most modern common strategies of synchronous CO2 and H2S removal is chemical absorption, i.e. the use of a Pressure Swing Absorber (PSA). In order to design an efficient plant, the characteristic acidic gas treating plant is mimicked utilizing Aspen HYSYS 8.8. The point of this mimicry is to attain the methane immaculateness of the natural gas by determining the optimum working pressure using a Pressure Swing Absorber (PSA) in which the feed sour gas is fed to the absorber at a concentration of 0.25 CO2 and 0.0004 H2S. The absorber parameters are: 30°C (temperature), 1.1 bars (initial pressure) and 15 m3/h (stream rate), and 25 wt. % monoethanolamine (MEA) concentrate. A 20-stage PSA with a tray diameter of 1.7 m is used. The results of the study show that in order to obtain natural gas with a methane purity of 95%, a PSA working pressure of 5 bars is needed.