Abstract—Two different mechanically agitated reactor vessels in mini scale size have been developed and fabricated to produce biodiesel . Esterification and transeterification routes have been chosen as the production process. Both refined bleached deodorized (cooking oil) and used cooking oil have been tested for the reliability of the reactor vessels. This paper will describe the engineering design for the reactor vessel development beginning at the stoichiometric equations for the production process and the thermal energy balance to the detail engineering including the equipment selection and fabrication in order to meet the design and objective specifications. Keywords: transesterification, energy balance, equipment selection I.INTRODUCTION ne of the objectives set in the Malaysia's National Biodiesel Policy is to exploit local technology to generate energy for the transportation and industrial sectors[2]. Driven by this policy and seeing the fact that the Johor state provides palm trees in abundant, the two different reactor vessels have been developed. The mini scale size is selected for the reason that a small company or a farmers community with their own fleets can produce biodiesel as fuel in a convenient manner. O The heart of biodiesel production employed on this study is esterfication of cooking oil with a high Free Fatty Acid (FFA) content with small amount of an acid catalyst before undergoing to transesterification for converting ester into Fatty Acid Methyl Ester or biodiesel. This simple synthesis process produces glycerine as by-product and therefore it needs to be removed by gravity separation following the complete reaction. II.BIODIESEL PRODUCTION By using methanol for the alcoholysis, the esterification and transesterification of the refined bleached palm oil can be expressed as follows:  This work was supported in part by Fundamental Research Grand Scheme. Winardi Sani is with the Department of Plant and Automotive Engineering, Faculty of Mechanical Engineering, University Tun Hussein Onn Malaysia (corresponding author to provide phone: 07-453 7813; fax: 07- 453 6080; e-mail: winardi@ uthm.edu.my). Dr. Khalid Hasnan is with the Department of Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, University Tun Hussein Onn Malaysia (corresponding author to provide phone: 07-453 7704; fax: 07- 453 6080; e-mail: khalid@ uthm.edu.my). Palm oil is used as the limiting reactant and the amount of methanol is in excess during the reaction. The stoichiometric reaction requires three mole of methanol for every one mole of the palm oil and it is an equilibrium reaction. The molar ratio of methanol/oil is fixed at 6:1 since the literature suggests that this is the optimal ratio for vegetable oil transesterification [1,3]. Sulfuric acid (H2SO4) and caustic soda (NaOH) are used as the catalysts in the esterification and transesterification, respectively. The isothermal reaction takes place at a temperature below the boiling point of methanol at atmospheric pressure, namely at 67 o C to ensure the conversion depends solely on the concentrations of the reactants[3] and preventing the methanol from vaporization. III.DESIGN SPECIFICATIONS AND EQUIPMENT Guided from the stoichiometric equation mentioned above, the design specifications are set as follows: (a) Above 90 % of conversion shall be achieved (b) Compatible materials must be used (c) Atmospheric operation pressure (d) Vessel capacity: 2 gallons (e) Hot water is used for heat supply (f) Ideal mixing in the continuous stirrer reactor vessel The conversion factor above 90 % is determined in a weight percentage of how much Fatty Acid Methyl Ester (Biodiesel) is earned per gallon of palm oil. The material for the inner vessel and the stirrer is made of stainless steel that is compatible to the chemical properties of the oil and glycerine. Zink is used for the outer vessel and a rock wool is utilized as the insulation material preventing a heat loss out the inner vessel, see Figure 1. Figure 1: Components of the reactor vessel Development of the mini scale biodiesel reactors Proceedings of MUCEET2009 Malaysian Technical Universities Conference on Engineering and Technology June 20-22, 2009, MS Garden,Kuantan, Pahang, Malaysia MUCEET2009 Winardi Sani, Khalid Hasnan