Study On Technologcial Conditions Of Transesterification And The Basic Properties Of Biodiesel

Biodiesel refers that recyclable animal or plant oil as feed reacts with alcohol of low molecular weight by transesterification, and then fatty acid ester of long chain is producted. Biodiesel is regarded that biodiesel from animal or plant oil is used as a kind of non-poisonous, environmental, and recyclable motor prostituted fuel,which not only is used alone,but also can be blended with mineral diesel,therefore it has a extentive prospect.This paper applied the method of theory analysis combining test. In this part, it put emphasis on how to make biodiesel fuel from vegetable oil and methanol with the catalyst of sodium hydroxide by transesterification. This paper analysed the different kinds of factors which influences the reaction conversion and yield. By orthogonality experiment, it was indicated that the optimal process condition for the transesterifrcation reaction of soybean oil was 1.0wt%(NaOH) of oil, the molar ratio of methanol and vegetable oil at six to one, the reaction time was 60 minutes, the reaction temperature was about 60℃. In this condition, the yield of biodiesel can reach 95.48%. The recovery and refining technology of glycerol from the by-product of transesterifrcation was researched. It was found that the best operation condition for the recovery and refining technology of glycerol was that the bottom layer of transesterifrcation production was diluted with methanol, then was neutralized to pH=5.0. The total yield of glycerol was up to 87.54%, the glycerol purity in the end-product was 97.05%.By comparing the property of biodiesel, diesel and the blended oil of biodiesel and diesel, it was showed that biodiesel was more environmentally friendly and more security than diesel, but its property of low-temperature, evaporation and atomization of biodiesel was not ideal. So blending biodiesel and diesel can learn from others's strong points to offset one's weakness and bring into play respective advantage. The density and the acid value of blended oil of biodiesel and mineral diesel were linear. But, the flash point, solidifying point and viscosity of blended oil were non-linear. Gas chromatography analysis showed that the carbon number distribution of biodiesel was concentrative and the distillation was narrow. The carbon distribution of B20(bio-diesel to mineral diesel is 1:4) was uniform, and accorded with the carbon number distribution of mineral diesel. So B20 of blended oil not only can improve the defects of biodiesel, but also can improve the quality of diesel.This paper applied the method of experiment and linear regression to contrast to the methods of density, kinematic viscosity and glycerine, which calculated the conversion ratio of transesterification. The paper established the simply method of calculating the conversion ratio of transesterification. The results showed that the error of the method of kinematic viscosity was within 2%. So the kinematic viscosity calculating conversion of transesterification has the feasibility to the different conversion of the same animal and vegetable oil and the different animal and vegetable oil. The error of the method of density was smaller than 8%, so this method can confirm the quality of the product.