Abstract—This paper presents a study on the thermodynamics and transport properties of hot potassium carbonate aqueous system (HPC) using electrolyte non-random two liquid, (ELECNRTL) model. The operation conditions are varied to determine the system liquid phase stability range at the standard and critical conditions. A case study involving 30 wt% K 2 CO 3 , H 2 O standard system at pressure of 1 bar and temperature range from 280.15 to 366.15 K has been studied. The estimated solubility index, viscosity, water activity, and density which obtained from the simulation showed a good agreement with the experimental work. Furthermore, the saturation temperature of the solution has been estimated. Keywords—Viscosity, Saturation index, Activity coefficient, Density. I. INTRODUCTION HE hot potassium carbonate process developed by Benson and Field (1970) [1] has since become an important technology used for CO 2 removal from natural gas streams using the chemical absorption method. The chemical solvent normally contains (20-40) wt% potassium carbonate, (1-3) wt% DEA activator and (0.4-0.7) wt%V 2 O 5 corrosion inhibitor. The normal operation conditions of CO 2 absorption process is; pressure range (1- 2 atm) and temperature range (70-140) 0 C based on the unit design [1]. Benfield solvent has a number of advantages which are support the system process compared with amine system and the other methods. These advantages can be conclude as; the absorption can occur at high temperature making the regeneration process more efficient and economical and potassium carbonate solvent is a low cost, low toxic and less prone degradation effects that are commonly found with MEA at high temperatures, presence of oxygen and the other gases [2]. Benfield solvent also has a large capacity for CO 2 [3], and it is more manageable by many of separation and/or cost effectiveness in the presence SO 2 [4]. The disadvantages of HPC solvent can be presented as; the carbon steel corrosion problem which is a cause by potassium carbonate solution [5], and the precipitation of the solvent in Omer Eisa Babiker Abdelgadir, MS.c student in Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Rizuan, Malaysia (phone: +60175767826; e-mail: omar22eisa@yahoo.com). Shuhaimi B Mahadzir, Head of Chemical Engineering Department, is with Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Rizuan, Malaysia (phone: +6053687622; fax: +6053656176; e- mail: shuham@petronas.com.my). form of fouling and crystals accumulations in Benfield reboilers system and pipeline. In a typical Benfield process, the two reboilers have been found prove too blockage due to formation of solid crystals. Laboratory analysis of the solutions taken from the two reboilers reported the content of 30-60 wt% potassium carbonate on dry basis. The work was aimed to study the thermodynamic properties of 30 wt% potassium carbonate solution and determine the precipitation conditions. The thermodynamic study of HPC solution describes the electrolyte system for explaining the effects of operation conditions on the electrolyte thermodynamics, chemical, and physical properties such as; heat capacity, activity coefficient, saturation index, viscosity and solution density and the other thermodynamics [6]. This leads to investigate the electrolyte phase equilibrium at vary operation conditions of pressure, temperature and solvent concentration. Aspen Plus simulator (Version 12.4) is used for modeling electrolyte systems. This related to the electrolyte data, reaction chemistry and the accurate electrolyte models which are build in Aspen database [7]. The calculations of thermodynamics and physical properties of K 2 CO 3 aqueous electrolyte in the vapor-liquid phase equilibrium based on two models; Redlich-Kown model for vapor-liquid equilibrium between water and carbon dioxide, and Electrolyte Nonrandom Tow-Liquid (ELECNRTL) for modeling activity coefficient [7, 8, 9]. This work focuses on the investigation of thermodynamic behavior of HPC system at different operation conditions by changing the effective parameters such as temperature, pressure and solutes concentration. Fig. 1 shows the electrolyte system simulation algorithm using Aspen Plus electrolyte template. II. REACTION CHEMISTRY The chemical composition of Benfield solution is described as ionic species generated from the reaction of solid hydration as well as water dissociation, and detailed equations of the stoichometry and the equilibrium reaction for the absorption of CO 2 in aqueous carbonate solution are given below [9]: Dissociation reactions: − + + ↔ 2 3 2 3 2 CO K CO K (1) − + + ↔ 3 3 HCO K KHCO (2) Thermodynamic Study of Hot Potassium Carbonate Solution Using Aspen Plus O. Eisa, and M. Shuhaimi T World Academy of Science, Engineering and Technology International Journal of Chemical and Molecular Engineering Vol:4, No:2, 2010 221 International Scholarly and Scientific Research & Innovation 4(2) 2010 scholar.waset.org/1307-6892/12194 International Science Index, Chemical and Molecular Engineering Vol:4, No:2, 2010 waset.org/Publication/12194