Rjeas Research Journal in Engineering and Applied Sciences 2(3) Rjeas

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1 Rjeas Research Journal in Engineering and Applied Sciences 2(3) Rjeas Emerging Academy Resources (2013) (ISSN: ) DEVELPMENT F A BIDIESEL PRCESSR 1 Emmanuel I. Bello, 2 Ilesanmi A. Daniyan, 1 Adebisi. Akinola, 1 Isaac T. gedengbe Department of Mechanical Engineering, 1 The Federal University of Technology, Akure, Nigeria. 2 Department of Mechanical Engineering. Afe Babalola University, Ado Ekiti, Nigeria. Corresponding Author: Emmanuel I. Bello A biodiesel processor was developed and consists of a 20- litre capacity reaction chamber in which the mixture was stirred by means of a mechanical stirrer with 7 blades and 4 baffles inside the chamber to reduce foaming and promote localized induced turbulence to enhance stirring. The stirrer is driven by a sparkless explosion proof electric motor through a reduction system to a maximum speed of 1000 rpm. The reactor is heated internally, thermally lagged and the temperature is controlled thermostatically to a maximum of 400 o C. The processor was tested with food grade palm oil and used cooking oils and the results obtained are similar to those for diesel fuel and within the specifications for biodiesel thus confirming that the processor can produce biodiesel within specification. This work aims at developing small biodiesel production plant that would enable small scale production of the commodity, for private consumption and commercial production. Emerging Academy Resources KEYWRDS: Biodiesel Processor, Stirring, Drive, Heating, Lagging, Performance Evaluation INTRDUCTIN The use of biodiesel as alternative fuel to diesel is gaining worldwide acceptability because it is a clean burning fuel, biodegradable, has low toxicity and is environment friendly. It contain no sulfur and does not contribute to green house gases as they have closed carbon dioxide cycle (Ma and Hanna, 1999; Pinto et al., 2008; Van Gerpen, 2005; Knothe, 2004). Biodiesel is a mixture of mono-alkyl esters of long chain (C16-18) fatty acids that can be obtained from a variety of vegetable oils and animal fats. It can be used as alternate fuel for diesel engines with little or no modification and gives performances close to those of diesel fuel. However, vegetable oils needs to be transesterified to biodiesel because of its high viscosity and poor cold flow properties by reacting it with an alcohol in the presence of an alkaline as catalyst. (Niehaus et al., 1985; Peterson et al., 1991). Transesterification is an equilibrium reaction in which the transformation occurs essentially by mixing the reactants and involves stripping the glycerin from the fatty acids and replacing it with an anhydrous alcohol, that is, usually methanol or ethanol as shown in Fig.1. In view of the fact that vegetable oil and alcohol do not mix readily and the reaction occurs mostly at the interface between them, they must be stirred vigorously to increase the area of contact any give high biodiesel yield (Singh and Fernando, 2006; Schuchardt et al., 1998]. H H H C C R 1 H C H R 1 C CH 3 (catalyst) H C C R 2 + 3CH 3 H H C H + R 2 C CH 3 H C C R 3 H C H R 3 C CH 3 H H Triglyceride Glycerol Biodiesel Fig.1. Transesterification Process The biodiesel yield, completeness of the transesterification and side reactions depends upon factors such as stir rate, reaction temperature, type of feedstock, catalyst type, catalyst weight, alcohol-to- 182

2 oil molar ratio, fatty acid composition and water content (Schuchardt et al., 1998). Biodiesel can be produced from fresh vegetable oil or used frying oil (Singh et al., 2006; Lapuerta et al., 2008; Dorado et al., 2003; Meka et al., 2007). Stirring can be done mechanically using a stirrer or recirculating pump. The challenge however, is to design a processor that will meet the varying requirements for a multifeedstock at the minimum cost, with high yield and quality. This work therefore aims at developing small biodiesel production plant that would enable small scale production of the commodity, for private consumption and commercial production. METHDLGY Literature searches were conducted and information product manuals sought from manufacturers on general requirements for a processor such as reactor sizes and shapes, stir methods and rates, effects of pressurization, energy balance, mass flow rates and safety procedures. Enquires were also made on catalysts forms and types, vegetable oil to alcohol ratios, reaction temperatures, effects of water contents and free fatty acid. The maximum temperature was set at 400 o C to be able to accommodate both methanol and ethanol. A schematic of vegetable oil transesterification processes was developed and shown in Fig. 2, to enable us determine where valves, pumps, seals can be located. A mass balance and flow analyses were undertaken for sizing purposes. It also helped in locating where heater, stirrer, lagging insulator, transducers can be located. NaH Mixer Vegetable il tank recovery Reaction Vessel Glycerol Separator Crude Biodiesel Pure Biodiesel Biodiesel Wash Basin Fig. 2: Biodiesel Production Schematic A study of the schematic shows the need for a sparkless electric motor to drive the mechanical stirrer in the reactor vessel because of the possibility of vapour exploding, a valve between the separator and reaction vessel and the need for lagging of the reaction vessel. To reduce costs it was decided to undertake the mixing in the reaction vessel to avoid the need for a pump in between the mixing chamber and the reaction vessel. The vegetable oil can be pumped or flow by gravity from the reservoir into the reaction vessel. RESULTS AND DISCUSSIN Reaction Chamber 183 The reaction chamber consists of two concentric cylinders of diameters 300 and 350 mm respectively and a capacity of 25 litres. The reactor is made from stainless steel and tapered at the bottom to take a discharge pipe and a ball valve to allow the mixture to be gravity drained. It has four internal baffles to reduce foaming and increase local recirculation. The reactor is lagged with saw dust which has very low high thermal conductivity and major disposal problem. Heating is by a 300kW stainless steel heating element heater at the bottom of the reactor vessel and controlled to give a maximum temperature of 400 o C. Temperature control is by means of a thermostat located at the bottom of the vessel. The whole design stands on three legs and is floor mounted. The chamber is covered at the top by a lid

3 that is bolted to the reactor body and a funnel is attached for feedstock feeding along with a relief valve since the system is pressurized. Each batch takes three hours to be completed and the product is drained to a wash tank. The sectioned drawing, the assembly drawing and the fabricated processor are shown in Figs. 3 and 4, and plate 1 respectively. Drive and Control System Mechanical stirrer was selected, the stirrer shaft is driven by a 2 kw 3000 Hz explosion proof sparkless dc motor mounted on the lid and driven via a reduction system. The motor speed is digitally controlled and has a maximum speed of 500 rpm to be able to cope with high density vegetable oil like castor and dika oils (Srivastava and Prasad, 2000; Bello et al., 2011a, Bello et al., 2011b) and wiring is explosion proof. Control Panel: All the gauges and control devices are ergonomically laid out on a control panel. Temperature and speed controls are regulated by dial control knobs and a status lamp is connected to the main switch. Fig. 3: Sectioned Drawing of the Processor Fig. 4: Assembly Drawing of the Processor Plate 1: The Fabricated Processor Transesterification Process 16 litres of methanol was poured into the reactor and 1.4% by weight of sodium hydroxide was added. The mixture was stirred at 200 rev/min for 30 minutes to form sodium methoxide and then drained into a storage vessel. 4 litres of palm oil was poured into the reactor and heated to 120 o C. The temperature was maintained for 30 minutes and then allowed to cool down to 60 o C. The methoxide was added to the oil at a molar ratio of 4 to 1 and stirred at 250 rev/min at a reaction temperature of 60 o C for 4 hours. The mixture was allowed to settle overnight so that the glycerol and biodiesel would separate into different layers. The mixture was drained into a decanter and separated. The biodiesel was washed with distilled water and then dried. The used frying oil was 184

4 also transesterified using sulphuric acid as catalyst because of its high fatty acid content which can inhibit biodiesel yield. Products Characterization The processor was tested using palm oil and used cooking oil and the biodiesels produced were characterized following the relevant ASTM protocols and the results obtained are shown in Table 1. All the properties are within the range specified by ASTM for biodiesel. Used frying oil biodiesel compared to that of palm oil biodiesel has higher specific gravity, relative density, cloud and pour points. But the flash point is lower than that of palm oil biodiesel. However, frying oil has higher kinematic viscosity (Lapuerta et al., 2008; Dorado et al., 2003; Encinar et al., 2005). Table 1. Properties of palm oil and used frying oil biodiesels Biodiesel Property Palm oil Used frying oil Diesel fuel Specific gravity Relative density (kg/m 3) Cloud point( o C) to -5 Pour point( o C) to -10 Flash point ( o C) minimum Kinematic viscosity (mm 2 /s) Performance Evaluation The performance of the processor was evaluated by varying the stir speed and noting the biodiesel yield at each speed, and as can be seen in Fig.5, the maximum yield occurred at 200 rpm. The yield was also measured at different reaction temperatures and at the optimal speed of 250 rpm. As can be seen in Fig. 6, the maximum yield occurred at 64 o C which is close to the evaporation temperature of methanol. CNCLUSINS The processor is capable of producing within specification biodiesel and achieved a biodiesel yield of 90% using palm oil and 60% for used cooking oil. The properties of the biodiesel are similar to those of diesel fuel and within the ASTM limits for biodiesel. The major problem encountered was power supply when testing the fabricated processor. REFERENCES Bello, E.I.; Fade-Aluko, A.., Anjorin S.A. and Mogaji T.S. (2011a) Characterization and Evaluation of African Bush Mango (Dika Nut) (Irvaingia Gabonensis) il Biodiesel as Alternative Fuel for Diesel Engines. JPTAF 2(9): Bello, E. I. and Agge, M. (2011b) Production, Characterization and Evaluation of Castor oil Biodiesel as Alternative Fuel for Diesel Engines. Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2(3): Dorado M.P., Ballesteros E., Arnal J.M., Gomez J., and Lopez F.J., Testing waste olive oil methyl ester as a fuel in a diesel engine. Energy Fuel, 2003; 17 (6): Encinar J.M, Juan F., Gonzalez J.F., Rodriguez- Reinares A, Biodiesel from used frying oil: Variables affecting the yields and characteristics of the biodiesel. Ind. Eng. Chem. Res., 2005; 44 (15): Knothe G, The Biodiesel Handbook, Chapter 2 - The History of Vegetable il Based Diesel Fuels, (2002) ISBN Lapuerta M., Rodriguez-Fernandez J., Agudelo J.R., Diesel particulate emissions from used cooking oil biodiesel. Bioresource Tech., 2008; 99 (4):

5 Ma F., Hanna M.A., Biodiesel Production: a Review. Bioresource Technology 1999; 70 (1):1-15. Meka P.K., Tripathi V., Singh R.P. Synthesis of biodiesel fuel from safflower oil using various reaction parameters. J. leo Sci., 2007; 56 (1):9-12. Niehaus R.A., Goering C.E., Savage L.D., Sorenson S.C., Cracked Soybean il as a Fuel for a Diesel Engine. ASAE Paper No.1985; 85:1560. ASAE, St. Joseph, MI. Peterson C.L., Wagner C.L., Auld D.L., Performance Testing of Vegetable il Substitute for Diesel Fuel. ASAE 1991; 81:3578. Pinto A.C., Guarieiro L.N., Rezende M.J., Ribeiro N.M., Torres E.A., Biodiesel:An overview, J. Brazil. Chem. Soc., 2005; 16 (6B): Schuchardt U., Serchelia R., Vargas R.M., Transesterification of vegetable oils: A review. J. Brazil. Chem. Soc., 1998; 9(1): Singh A.K. and Fernando S., Catalyzed fast transesterification of Soybean oil using ultrasonication., American Society of Agricultural Engineers, ASAE Annual Meeting, 2006;Paper # Singh A.B.H., Thompson J., Van Gerpen J., Process optimization of biodiesel production using different alkaline catalysts. Appl. Eng. Agric., 2006; 22 (4): Srivastava, A., R. Pras, ( 2000) Performance of a diesel generator fuelled with palm oil. Fuel Renewable Sustainable Revolution 4: Van Gerpen J., Biodiesel processing and production. Fuel Process. Tech., 2005; 86 (10):