1. Petroleum and Gas Refinery Engineering Department, College of Petroleum Process Engineering, Tikrit University, Tikrit P.O. Box 42, Iraq
2. Chemical Engineering Department, College of Engineering, Tikrit University, Tikrit P.O. Box 42, Iraq
3. Ministry of Oil, North Refineries Company, Baiji Refinery, Tikrit P.O. Box 42, Iraq
4. Department of Chemical Engineering, Faculty of Engineering & Informatics, University of Bradford, Bradford BD7 1DP, UK