Study on Redressing the Thermodynamic Property Package forProcess Simulator

Abstract This paper describes the importance of redression of binary interaction parameter for selected thermodynamic property package in process simulator. The work has been made in this paper to redress the binary interaction parameter for non-ideal or complex binary systems of 2-ethoxyethanol + di-n-propyl ether, 1-propanol + 2-ethoxyethanol, 1-propanol + di-n-propyl ether. In this study, redressed value of the binary interaction parameters for UNIQUAC model fitted in CHEMCAD simulation software for comparing the bubble point pressure from experimental data and simulator data to increase the accuracy of simulation result. Keywords: Activity coefficient, Binary interaction parameter, Redression, Regression, 2-ethoxyethanol, 1-propanol. 1. Introduction Di-n-propyl ether (DPE) can be manufactured from reaction of 1-propanol (PA) with H 2 SO 4 , and complete separation of di-n-propyl ether can be archived with the help of 2-ethoxyethanol (trade name is Cellosolve) as solvent. Cellosolve mainly used as a solvent in industries or laboratory practices to dissolve resin, waxes, lacquers, grease, oils and nitrocellulose. Extractive distillation operation is used for separation of a DPE + PA. Cellosolve form a complex or non-ideal mixture with 1-propanol and di-n-propyl ether [1]. For designing of a distillation system vapor liquid equilibrium (VLE) data play vital role in it [2]. Process simulator like CHEMCAD simulation software can be used for design of such distillation system. Process simulator is an outstanding tool for analyzing, designing, rating and optimizing the process plants, refineries, chemical plants. In process simulator, various kind of thermodynamic property packages are used such as equation of state (EOS), activity models, vapor pressure models, chao seader and grayson streed models, other special models etc. Mainly thermodynamic activity models are used for non-standard or complex system. Binary interaction parameter (BIP) is the heart of the activity model and its value calculated with the help of the data regression analysis from experimental vapor liquid equilibrium (VLE) data. However, no one of activity model is accurate and often some adjustment must be done before their applications. Researchers have already provided BIP data for various mixtures in databank of process simulator. Before actual simulation, must check the accuracy and validity of thermodynamic property package. Convergence of flowsheet in process simulator does not give the guaranty of correct results [3]. Use of improper redressed binary interaction parameter (BIP) in process simulator which generates the result which deviates from reality. Prior to their application of process simulator with thermodynamic property package redressing of the binary interaction parameter with checking the converged result and its accuracy within allowable range, if not then thermodynamic property package should be redressed to enhance its accuracy [4]. This redressing can be done by VLE calculation such as dew point, bubble point or flash calculation and comparing the result with experimental data. Experimental VLE data for 2-ethoxyethanol + DPE (Table 1) [5], PA + 2-ethoxyethanol (Table 2) [6], PA + DPE (Table 3) [7] system has taken from literature and simulated VLE data is generated from CHEMCAD V6.0, using UNIQUAC thermodynamic activity model.