Browsing by Author "Minja, Rwaichi J.A."

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    Modifying Plant Oils for Use as Fuel in Rural Contexts Tanzania: Techno-Economic Analysis
    (Open Journal of Modelling and Simulation, 2014-04) Mlay, Happiness; Katima, Jamidu H. Y.; Minja, Rwaichi J.A.
    Techno-economic analysis of a small-scale Modified Plant Oil (MPO) production plant that has an annual production capacity of 15,072,741 kg of MPO (batch process) was carried out to estimate the capital and operating costs of a plant. The analysis was done by using a computer model that was designed and simulated with an aid of SuperPro Designer (Version 4.32) software. The specified feedstock was crude Jatropha oil (JO) and the main product was MPO. The major processes involved were degumming, neutralisation and blending. Degumming involved the removal of gums or phospholipids, and two methods were used: water degumming and acid degumming, whereas blending involved mixing of degummed or purified JO with natural gas condensate (NGC) modifier to lower the viscosity of JO. From techno-economic analysis of the process, it was found that the total capital investment of a plant was about US $ 10,222,000 and the predicted unit production cost of MPO was US $ 1.315/kg at a value of US $ 1.0/kg of JO. The economic feasibility of MPO production was found to be highly influenced by the price of feedstock, which contributed about 95% of the total annual production cost. The relationship between plant throughput and unit cost of producing MPO showed that unit production cost was very sensitive to production rate at low annual throughputs. The MPO cost showed a direct linear relationship with the cost of JO, with a change of US $ 0.50/kg of MPO in MPO cost in every change of US $ 0.50/kg of JO in JO price. The process technology simulated was found to be economically viable and can be implemented in rural setting, taking into consideration Tanzania’s rural situation.
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    Plant Oil Blends as Alternative Fuels for Low- and Medium Speed Diesel Engines: Natural Gas Condensate Utilisation
    (American Journal of Engineering, Technology and Society, 2015-04-20) Mlay, Happiness; Katima, Jamidu H.Y.; Minja, Rwaichi J.A.
    The high viscosity of pure plant oils (POs) reduces the feasibility of using plant oils as diesel engine fuel as reported by various researchers. Fuel blending is one of the methods of lowering viscosity. A study was carried out on fuel properties of Jatropha (JO) and Croton (CROT) seed oils blended with a by-product of Songosongo natural gas extraction - natural gas condensate (NGC) (modifier) of between 5% and 50% (v/v) at room temperature (30 ± 3˚C). Mixture design was used to analyse the effect of NGC composition in the resulting blend on the kinematic viscosity and fuel combustion properties of the blends. The results were also compared to the properties of crude POs and diesel fuel (grade 4-D) specifications. The blends were found to be compatible over a wide range of compositions and exhibited much lower viscosity and better combustion properties than crude plant oil (PO) samples. The optimum parameters for formulating blends were found to depend on the modifier characteristics and that 10% (v/v) NGC was enough to produce the desired liquid biofuel blend. The characteristics of blends presented in this work meet the specifications for diesel fuel grade 4-D and so matches well with the characteristics of fuels for low- and medium-speed diesel engines. This implies that the PO/NGC blends may be potential alternative fuels in low- and medium speed diesel engines, which are common engines found in rural areas and so PO/NGC blends fuels may contribute in meeting rural’s energy self-sufficiency while at the same time making utilisation of natural gas condensate.
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    Plant Oil/Fusel Oil Blends as Alternative Fuels in Low- and Medium Speed Diesel Engines
    (American Journal of Energy Science, 2015-04-10) Mlay, Happiness; Katima, Jamidu H.Y.; Minja, Rwaichi J.A.
    Fuel blending is one of the methods of lowering plant oil’s viscosity, which is the major parameter that leads to serious problems on diesel engine performance in terms of operation and durability. A study was carried out on fuel properties of Jatropha (JO) and Croton (CROT) seed oils blended with a distillery by-product, fusel oil (FO) (modifier) of between 20% and 50% (v/v) at room temperature (30 ± 3˚C). The effect of FO composition in the resulting blend on the kinematic viscosity and fuel combustion properties of the blends was analysed. The results were compared to the properties of crude plant oils (POs) and diesel fuel (grade-4D) specifications. The blends were found to be compatible over a wide range of compositions and exhibited much lower viscosity and better combustion properties than crude plant oil (PO) samples. The optimum proportions for a blend’s viscosity to meet the specifications for diesel fuel (grade 4-D) were found to depend on the modifier characteristics; and that 20% (v/v) FO was enough to produce the desired liquid biofuel blend. The characteristics of blends presented in this work matches well with the characteristics of fuels for low- and medium-speed diesel engines. This implies that the PO/FO blends can be used as alternative fuels in low- and medium speed diesel engines.