Development and Performance Evaluation of a Small Scale Biodiesel Production Pilot Plant

Transcription

1 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 4(4): Scholarlink Research Institute Journals, 2013 (ISSN: ) jeteas.scholarlinkresearch.org Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 4(4): (ISSN: ) Development and Evaluation of a Small Scale Biodiesel Production Pilot Plant Oseni M.I, Tuleun L.T. and Musa A. Mechanical Engineering Department, Federal Polytechnic, Idah, Nigeria. Corresponding Author: Oseni M.I Abstract A pilot plant for the production of biodiesel was developed and tested. The components of the plant were fabricated locally through welding, casting and machining, and assembled by bolting. The plant was tested by producing soy oil ethyl ester (SEE biodiesel), using soy oil and ethanol, with potassium hydroxide as catalyst. The test showed that, with 80.50litres of the reactants, the plant is capable of producing a maximum of litres of biodiesel, at 60minutes of mixing time and with a performance efficiency of 82.98%. Chemo-physical properties of the biodiesel samples obtained were determined and found to fall within the range of biodiesel standard. Specific gravity of samples A, B, C (0.87, 0.88, 0.90) were little above that of reference petroleum sample (0.8377); kinematic viscosity of (3.20, 2.80, 3.70) were little below that of reference petroleum diesel (4.21), though still within the biodiesel kinematic viscosity standard of cst (ASTMD 6751). The percentage free fatty acid values of the three test samples were higher than that of the reference petroleum diesel. The cloud point and pour point obtained for the three samples are; (9 0 C, 7 o C, and 6 0 C) and(5 o C, 8 o C,and 5 o C), as against reference diesel (-11 0 C and C) respectively. These results imply that this pilot plant is capable of being used as a biodiesel processing plant, and it can produce litres of biodiesel in 18 hours. The purpose of this research work is to design and construct a machine that can be used to produce biodiesel locally. This will reduce the dependence on petroleum based diesel; create sustainable wealth for the biodiesel feedstock farmers. Less smoke and less soot will be the result from unburned fuel. The improved combustion efficiency will lower particulate materials and unburned fuel emissions. The pilot plant when installed in many locations in this country will reduce importation of petroleum product, reduce greenhouse gas emissions, establish new rural industry, counter labour migration to major cities, stabilizes income to farmers and develop new agricultural market. Keywords: production, performance evaluation, biodiesel production, pilot plant INTRODUCTION The rise in oil prices in the recent years has had a great impact on both the agricultural and industrial sectors because of higher cost of production. The loss in foreign exchange through the importation of petroleum products has caused the Nigerian government to consider new sources of energy to substitute for petroleum products. Besides the spiraling prices of petroleum products the cost of use of these products to the environment has also escalated. The depletion in the ozone layer accompanied by global warming and unfavorable climatic changes are major concerns to producers and users of fossil fuel. Renewable energy source such as bio-diesel is therefore considered to be an immediate solution to this emerging problem. Biodiesel is the name of a clean burning alternative fuel produced from domestic, renewable resource. It is produced by the transesterification of vegetable oils in the presence of ethanol or methanol with potassium hydroxide or sodium hydroxide as catalyst, to yield neat biodiesel (BD 100 i.e. 100%) with glycerol as the byproduct. Biodiesel contain no petroleum, but it can be blended at any level with petroleum diesel to create a biodiesel blend. The blend of 80:20 ester diesel (B20) has given the best performance so far (Kleber, 2004). Plants amenable to biodiesel production include oil palm trees (Elias guinesis), calabash seeds (lageneria vulgaris), soya beans, etc. Biodiesel can be used in compressionignition (diesel) engines with little or no engine modifications. Biodiesel is simple to use, biodegradable, non-toxic and essentially free of sulphur and aromatics (Michael, 2004). Among the attractive features of biodiesel fuels are: i) It is plant, not petroleum, derived and as such its combustion does not increase current net atmospheric level of CO 2, a greenhouse gas ii) It can be domestically produced, offering the possibility of reducing petroleum import. iii) It is biodegradable iv) Relative to conventional diesel fuel, its combustion products have reduced levels of 679

2 particulates, carbon monoxides, and under some conditions, nitrogen oxide. The lack of toxic and carcinogenic aromatics (benzene, toluene and xylene) in bio-diesel means the fuel mixture combustion gases will have reduced impact on human health and the environment (Koerbitz and Kossmann, 2003). The high cetane number of biodiesel (ranges from 49 to 62) is another measure of the additives ability to improve combustion efficiency (Randall, 1999). As an oxygenated vegetable hydrocarbon, biodiesel itself burns clearly, but it also improves the efficiency of combustion in blends with petroleum fuel. Biodiesel reduces long term engine wear in test diesel engines to less than half of what was observed in engines running on current low sulphur diesel fuel. Lubricity properties of fuel are important for reducing friction wear in engine components normally lubricated by the fuel rather than crankcase oil (Howell, 2004). The intent of this study is not to replace petroleum diesel entirely as a fuel, but to design a plant for biodiesel production to displace it in key applications where the environmental impacts of petroleum diesel fuel are most threatening and can be easily muted by replacing the fuel with biodiesel or a blend of biodiesel.consumption of petroleum diesel has been found to be a source of pollution to our environment and has added to the overall cost of running production machinery. These pollutants are hazardous to the environment and affect human health, agricultural productivity, natural ecosystems and the ozone layer. Petroleum diesel emissions contain high concentration of greenhouse gas (GHG) emissions such as carbon dioxide (CO 2 ), carbon monoxide (CO), poly aromatic hydrocarbons (PAH), NO x, particulate matter (PM) and hydrocarbon emission which are pollutants affecting the environment (Verma and Thomas, 2001). With the high concentration of emissions, the increasing cost of exhaustible energy sources particularly crude oil is alarming in the world market and petroleum diesel has taken its fair share of high cost. With increased demand and un-substituted use of this exhaustible fuel, an energy crisis could happen in the nearest future. Biodiesel is biodegradable and environment friendly during use, thereby reducing exhaust emissions of carbon monoxide and totally eliminating sulphur emission while serving as a very effective lubricity enhancer in diesel engines. Substitution of conventional petroleum diesel with biodiesel from palm oil and calabash seed oil would go a long way to reducing environmental pollution, cost of equipment maintenance and find a new use for agricultural products. The research work aims at developing from local technology a pilot plant for small scale production of biodiesel and evaluating its performance efficiency. Its significance is that production of biodiesel will reduce the dependence on petroleum based diesel, create sustainable wealth for the biodiesel feedstock farmers. Less smoke and less soot will be produced from unburned fuel. While the oxygen contained in the fuel will increase efficiency of combustion even for the petroleum fraction of the blend. The improved combustion efficiency would lower particulate materials and unburned fuel emissions especially in older engines with direct fuel-injection systems (Randall, 1999). Biodiesel and biomass-based diesel reduced greenhouse gas emissions by 50% compared to petroleum diesel fuel (Gerpen and Tat, 2003). Biodiesel was shown to enhance the biodegradation rate for diesel fuel in a blend. Because biodiesel is a single, straight carbon-chain with two oxygen at one end (mono-alkyl ester),; it is more readily metabolized by bacteria that normally breakdown fats and oils in the environment. The petroleum diesel hydrocarbons lack oxygen, and represent a very complex mixture of hydrocarbons with multiple double bonds, and many other branched cyclic and cross linked chains. The more complex chemical structures of diesel hydrocarbons make them more difficult to biodegrade and in many cases, toxic (Randall, 1999).With increased use of biodiesel fuel, the disturbance of the natural environment such as the ozone layer, agriculture and climatic change will be reduced. STATEMENT OF THE PROBLEM Consumption of petroleum diesel has been found to be a source of pollution to our environment and has added to the overall cost of running production machinery. These pollutants are hazardous to the environment and affect human health, agricultural productivity, natural ecosystems, and the ozone layers. Biodeisel is biodegradable and environmental friendly during use. Substitution of conventional petroleum diesel with biodiesel would go a long way to reducing environmental pollution, cost of equipment maintenance and find a new use for agricultural product. LIMITATION OF THE STUDY This work is limited to the design and construction of a biodiesel pilot plant and the evaluation of the plant with production of biodiesel from soy oil by a process of transesterification of oil and ethanol with potassium hydroxide as a catalyst. The biodiesel pilot plant constructed was designed to handle all the plant seed oils as feedstock. 680

3 MATERIALS AND METHODS The materials used for this work were selected based on the process requirements and availability. The design calculations and materials selection were done base on standard engineering procedures. The construction work was done at the Mechanical Engineering workshop of the Federal Polytechnic Idah, Kogi state, Nigeria. The pilot plant constructed was tested in the Mechanical Engineering workshop of the University of Agriculture Markudi, Benue state, Nigeria. Testing of the plant was carried out and biodiesel was produced by transesterification of soy oil in the presence of ethanol and potassium hydroxide as catalyst. The materials used for the construction of the plant are mild steel angular bar (2 inch size), aluminum, mild steel sheet G 16, mild steel rod (25 mm), ¾ inch gate valves, ¾ inch taps, 0.125hp electric motor, mitre bevel gears, heating element and galvanized pipes. The oil used for the production of the biodiesel is soy oil and it was bought from the open market, and the quantity used was 11.5 liters. The amount of ethanol used in the production was 69 liters and 63g of potassium hydroxide was used as catalyst. At the end of transesterification process, litres, litres and litres of biodiesel were obtained for the samples A, B and C respectively, while litres, litres and litres of glycerol were obtained for samples A, B and C respectively. RESULTS AND DISCUSSION The performance evaluation of the designed pilot plant was carried out, and the test results are presented in the Tables 1, 2, 3, and 4. The product, soy oil ethyl ester (biodiesel) obtained from the testing of the plant were analyzed and results are shown in Table 5. The biodiesel pilot plant constructed was designed to handle all the biodiesel feed stocks. The choice of soy oil for the testing of the plant was just based on its availability. The Designed Biodiesel Pilot Plant The four major units of the plant (Reactor, Decanter, washing, and drying vessels) were arranged in two columns, and are coupled in such away that, flow from the first unit to the other units is by gravity. Another thing unique about the plant is that, the Reactor (a baffled vessel, with four baffles arranged at 90 o to each other) is steam heated and is automatically controlled with the aid of thermocouple. In this pilot plant, the Reactor and the washing vessel are two independent units such that mixing of reactants and washing of biodiesel can be carried out separately and at the same time. The implications of operation of the designed pilot plant are as follows:- Since the plant requires water and electricity to operate, it implies that, the plant must be installed in a free and clean environment, where there is access to water and electricity. For complete reaction of the reactants and improved quality of biodiesel to be produced, the ratio of oil, alcohol and catalyst must be strictly followed and the potassium hydroxide must be weighed accurately, and also, the ethanol must be measured accurately, mixed and dissolved completely to form ethoxide before pouring into the oil in the reactor. Since the decanter and the washing vessels are not transparent, the settlement and separations of the stages 2 and 3 was carried out using transparent plastic buckets. This was to ensure that, complete separation was observed before the removal of the biodiesel. The designed biodiesel pilot plant has a volume of 90 litres and it is capable of producing a maximum of litres of biodiesel per batch, within 6 hours (i.e litres of biodiesel in 18 hours). Evaluation of Test Biodiesel Chemo-physical properties of the three samples of soy biodiesel (A, B, C), reference petroleum diesel, and soy oil samples determined experimentally are displayed on Table 5. The specific gravity of tests biodiesel samples were a little lower than that of reference petroleum diesel sample, while that of soy oil being the lowest. Fig.4. shows a phenomenal increase in specific gravity of the five samples, and the corresponding densities in kg/m 3 and American petroleum institute (API) gravity for all the samples are also presented in Table 5. The API gravity of soy oil recorded the highest value, followed by that of the three biodiesel samples; with the reference petroleum diesel fuel beingthe least. This is because soy oil has higher free fatty acids and higher specific gravity when compared to the reference petroleum diesel and biodiesel. The kinematic viscosity of test biodiesel fuel is an intrinsic spray characteristic of the fuel within an engine, and a change in spray can greatly affect the combustion properties of the mixture (James, 2002). The values 33.45, 3.20, 2.80, 3.70, and 4.21 were obtained experimentally for the five samples (soy oil, test biodiesel samples (A, B,C) and petroleum dieselrespectively).the values for test biodiesel and reference petroleum falls within the biodiesel kinematic viscosity standard of cst (ASTMD 6751).These viscosities affect the fuels size during injection. Biodiesel droplet sizes are larger than that of references petroleum diesel hence making reference petroleum diesel spray slightly better but with higher fuel consumption than biodiesel during combustion process. The higher the kinematic viscosity as biodiesel content reduces in blends, the lower their pour point, the lower their free fatty acid value, the lower their specific gravity and the higher 681

4 their volatility with a better combustion quality in a diesel engine. This is because biodiesel pour point is lower than that of the petroleum diesel, and the free fatty acid values of biodiesel is higher than that of the petroleum diesel, and also the specific gravity of biodiesel is higher than that of the petroleum diesel. This helps to ensure low carbon residues and minimize crank case dilution (James, 2002). The percentage free fatty acid values of the test biodiesel is higher than that of the reference petroleum diesel fuel but the soy oil recorded the highest, among the five samples. Free fatty acids for natural oils are normally higher than that of mineral base oils (Hartley, 1998 and Oyinola, 1984). Open flame test shows that the flash point of the test biodiesel was higher than that of the reference petroleum diesel and soy oil being the highest (as in Fig.6.). That is, the flash points for the five samples, soy oil, test biodiesel samples (A, B, C) and reference petroleum were C, C, 141 o C, 122 o C and 60 0 C respectively. This decrease was attributed to higher volatility of reference petroleum diesel. According to ASTM D6751, the flash point of C, 141 o C, and 132 o C were in conformity with the biodiesel standard flash point specification of > C. The value of reference petroleum diesel obtained also falls within standard petroleum diesel specification of 52 0 C to 71 0 C. Flash point that is too low causes the fuel to be a fire hazard, subject to flashing and possible continued ignition and explosion. In addition, a low flash point indicates contamination by a more volatile and explosive fuel such as premium motor spirit (James 2002). The cloud point and pour point obtained for soy oil (8 0 C and 9 0 C), test biodiesel samples A (9 0 C and 5 0 C), B (7 o C and 8 o C), C (6 o C and 5 o C) and reference petroleum diesel (-11 0 C and C), are also shown in Table 5. However, it was observed by Herguth and Godfrey (1995) that, the lower the cloud and pour points of oils the better the pumping property at startup of engines at relatively low temperatures. But at high cloud and pour points when temperature are relatively low, the oil tends to congeal causing problems at start up and increasing the coefficient of friction thereby generating heat and wear.the reference petroleum diesel has relatively lower cloud and pour point (-11 0 C and C)than the test biodiesel samples and soy oil. Table 5 shows that the petroleum diesel had a high moisture content of 9.23 percent as compared to test biodiesel samples with very low moisture content of (1.13, 0.85, and 0.87) percent for samples A, B, and C, respectively. The soy oil recorded the highest moisture content of 18 percent. This implies that the produced biodiesel samples have lower risk of contributing to filter blocking and causing corrosion of the injector system components according to (James, 2002). CONCLUSION A biodiesel pilot Plant that has a volume of 90 litres has been designed, constructed and tested. The plant was tested using soy oil and ethanol with potassium hydroxide as catalyst. The pilot plant was test run and the test biodiesel was comparable to reference petroleum diesel. Hence this pilot plant has the capability of being used as a biodiesel processing plant. From the test carried out, it was shown that, using 30 minutes, 60 minutes and 90 minutes of mixing time, litres of the reactants yielded litres, litres and litres of biodiesel for the 3 samples A, B and C respectively. And the performance efficiency of the pilot plant for the 3 samples A, B, C are 66.95%, 82.98% and 74.10%. Statistically, it was demonstrated that, reaction time is a valid factor in the biodiesel production. The pilot plant when installed in most district of this country will reduce importation of petroleum products, reduce greenhouse gas emissions, establishes new rural industry, counter labour migration to major cities, stabilizes income to farmers and develop new agricultural market. REFERENCES ASTM (2004), Biodiesel standard specification. visited on 03/08/2009. Gerpen V.J and Tat M..E. (2003). Fuel Property Effects in Biodiesel. ASAE paper No America Society of Agricultural Engineering Annual meeting. Las Vegas, July 27-30pp.1, 18,21 http// Herguth, R. and Godfrey D. (1995) Physical and chemical properties of mineral oils that affect lubrication. on 24/08/2009. Hartley, C.W.S (1998). The oil Palm, 3 rd edition. Tropical Agricultural sciences, New York, longman scientific and Technical Publication. Howell, S. (2004), Update Reports on Lubricity Of Biodiesel, Mark-IV Group, Keavny, MO, Sponsored By The National Soy Diesel Development Board, October, James G.S (2002). Handbook of petroleum product analysis. John Wiley and Sons Inc, Publication United States of America. Kleber, M. (2004). Biodiesel Technology With Emphasis On Animal Feed Stocks, NBB National Biodiesl Conference. January 2004, Palm Springs, California, USA. 682

5 Koerbitz, W. and Kossman J. (2003). Production and Use of Biodiesel. Risoe Energy Report 2, Risoe National Laboratory. Michael B. (2004). Wide Scale Biodiesel production from algae. United States department of energy, office of energy efficiency and revewable energy. Oyinola A.K.(1984): Determination of performance characteristics of local oils as lubricants. Nigeria journal of engineering. (2)1. Randall V. W. (1999). Technical Handbook for marine biodiesel in Recreational boats. Prepared for the National Renewable energy laboratory, U.S. Department of Energy. Subcontract No. ACG , under prime contract No. DE-AC36-83CH Verma E.R and Thomas T.A (2001). The size distribution of particles in petrol and diesel vehicular emissions. Bostwana journal of Technology. Faculty of Engineering and Technology. University of Bostwana. Gomboro. Vol. 10 No1 APPENDIX Oil base Alcohol Batch Reactor Catal Glycerine + Glycerine Decanter Ester Washing Tank Glycerine + FFA Ester + Water Drying Tank Water Ester Packaging 683

6 23 Frame 2 x 2 inch 1 Ms 22 Washing tank G 16 1 Ms 21 Boalts / nults - - Ms 20 Wash water valve ¾ inch 1 Brass 19 Water heater 1000W 5-18 Cold water valve ¾ inch 1 Brass 17 Mixing blades - 2 Al 16 Baffles Flat bar 4 Ms 15 Mixing shafts - 2 Ms 14 Reactor vessel G 16 1 Ms 13 Bearing housing - 2 C I 12 Electric motor hp 2 - Fig. 1: Block diagram showing the different stages of biodiesel Pilot Plant Fig. 3: Section view of the biodiesel Pilot Plant 11 Bevel gear - 4 Ms 10 Gear cover G 16 2 Ms 9 Reactor cover G 16 1 Ms 8 Glycerol/Biodiesel valve ¾ inch 1 Brass 7 Hot water valve ¾ inch 1 Brass Fig. 3: Section view of the biodiesel Pilot Plant (Drawing not to scale) 6 Decanter G 1 Ms Plate 1: Photograph of the Biodiesel Pilot Plant 684

7 Table 1: Reactor and Decanter Tests Data Samples Mixing time (mins) Biodiesel yield Glycerol yield Qnty of reactant efficiency (%) Mixing rate (litre/min) litres % litres % A B C specific gravity Table 2: Washing Vessel Tests Data Samples Washing time (mins) Reactants (ester + water) (liters) Table 3: Drying Vessel Tests Data Table 4: Pilot Plant Evaluation Data Table 5: Comparative Analysis of Chemo-phyiscal Properties of Soy Oil, Test Biodiesels and Petroleum Diesel Properties ASTM D6751 Soy oil Sample Petroleum diesel A B C Kinematics 40 0 C (Cst) Specific 15 0 /15 0 C > Density (Kg/m 3 ) API gravity Free fatty acid (%FFA) Flash point ( 0 C) > Fire point ( 0 C) Pour point ( 0 C) -15 to Cloud point ( 0 C) Moisture content (%) Biodiesel yield Percentage Free Fatty acid(% FFA) efficiency (%) A B C Samples Drying time (mins) Biodiesel yield (before drying) Biodiesel yield (after drying) Biodiesel yield (%) efficiency (%) rate (litre/min) rate (litre/min) A B C Samples Input(Reactants) Output(Ester) efficiency (%) A B C f Figure 5: Percentage (FFA) of oil samples Figure 7: Kinematic viscosity of oil samples 685