* Corresponding author. Tel.: #00966-1-4676873; fax: #00966-1- 4678-770. E-mail address: szahrani@ksu.edu.sa (S. M. Al-Zahrani). Chemical Engineering Science 56 (2001) 621}626 Modelling and simulation of 1,2-dichloroethane production by ethylene oxychlorination in #uidized-bed reactor S. M. Al-Zahrani*, A. M. Aljodai, K. M. Wagialla Chemical Engineering Department, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia SABIC R&T, P.O. Box 42503, Riyadh 11551, Saudi Arabia Abstract A comprehensive reactor model for ethylene oxychlorination for the production of 1,2-dichloroethane in a #uidized-bed reactor is developed. The model is based on the two-phase theory of #uidization and allows for the change in volumetric gas #ow rate in the dense phase due to the change in number of moles accompanying the reaction. The model predictions compared favorably with the industrial data obtained from the literature. The e!ect of di!erent parameters on the behavior of the system is also investigated. It has been found that the bubble diameter, ethylene molar feed fraction, residence time, and height at minimum #uidization have signi"cant e!ects on the reactor performance.  2001 Elsevier Science Ltd. All rights reserved. Keywords: Dichloroethane; Oxychlorination; Ethylene; Fluidized-bed; Modelling; Simulation 1. Introduction Vinyl chloride monomer (VCM) or (CH  "CHCl) is the basic feed for the production of polyvinyl chloride (PVC), which is one of the most massively produced thermoplastics in the chemical industry. The current worldwide VCM production capacity is about 24 MM ton per year (SRI report, 1998). VCM is produced commercially by cracking of 1,2 dichloroethane (CH  CH  Cl  or EDC) which is manufactured worldwide by either the direct chlorination or oxy- chlorination of ethylene. Around 85% of the total EDC production is used for the production of vinyl chloride. 10% is used in the production of chlorinated solvents such as 1,1,1-trichloroethane and tri- and tetrach- loroethylene. The rest goes into various processes, mainly for synthesis of ethylenediamines (Nawroski & Velez, 1983). In commercial ethylene oxychlorination reactors, gas- eous ethylene, HCl, and air (or oxygen) catalytically react at temperatures in excess of 2003C to produce EDC. The overall chemical reaction is C  H  #0.5O  #2HCl  &&  CH  CH  Cl  #H  O, H  "!295 kJ/mol Typically, the catalyst is composed of cupric chloride supported on high-surface-area alumina. Although other supports such as graphite, silica gel, calcined Fuller's earth, diatomaceous earth, pumice, or kieselguhr may be used, alumina is generally preferred because of its perfor- mance, attrition resistance and the ability to control its surface area (Ullmann, 1986). Other metal salts, such as potassium, sodium, or aluminum chloride, may be added to the catalyst to increase selectivity and reduce volatiliz- ation of the copper chloride (Ullmann, 1986). Because the oxychlorination reaction is highly exothermic, substantial quantities of heat must be re- moved from the reactors. Fluidized-bed reactors have many advantages in this system. Near-isothermal opera- tion can easily be achieved with a well-#uidized catalyst, giving an overall heat-transfer coe$cient to the cooling surface in the range of 250}500 W/mK (Smallwood, Stephenson, Newman & Bunten, 1987). In #uidized beds, the heat is removed by internal cool- ing coils that are submerged in the #uid bed (Smallwood, Stephenson, Newman & Bunten, 1987). Reaction temper- atures are generally controlled in the range 210}2403C. 0009-2509/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved. PII: S 0 0 0 9 - 2 5 0 9 ( 0 0 ) 0 0 2 6 8 - 2