Near-critical-region equilibria of the CH 4-CO 2-H 2S system

Abstract

Morris J.S. and Byers C.H., 1991. Near-critical-region equilibria of the CH 4-CO 2-H 2S system. Fluid Phase Equilibria, 66: 291-308. To acquire data for assessing a proposed syngas purification system, an apparatus has been built to measure vapor-liquid equilibria of binary and multicomponent systems in the critical region of CH 4-CO 2-H 2S mixtures. To test the experimental device and supplement existing data, binary systems were studied between 270.0 and 288.2 K. Predictions of the Peng-Robinson (PR) and Redlich-Kwong-Soave (RKS) equations of state were compared with binary and ternary data using the ASPEN simulator parameter regression utilities to determine binary interaction parameters from binary data. Calculated phase equilibria for CH 4-CO 2 mixtures based on both equations agree to within 3.5%, while the difference in either case with experimental liquid phase compositions is less than 15%. Similar results were obtained for CO 2-H 2S mixtures. Experimental values were less reliable for CH 4-H 2S binary interaction parameters. In predicting the ternary mixtures, total pressure is generated using both equations of state. Estimates by the PR equation were significantly better than those generated by the RKS equation (12% deviation versus 29% deviation) for the temperature and pressure range of the study.