| Transforming the waste vegetable oil to the substitute fuel replacing the fossil diesel has a good perspective, which can not only reduce the pollution and economize the energy but also reduce the density of the atmosphere made by the green house effect and improve the ecosystem environment.In this work, by physical and chemical processing the waste vegetable oil of daily life was transformed to the substitute fuel. A kinetic model of conversion process of waste vegetable oil was established based on the studying of the process, transforming mechanism and the reacting kinetics. At last the combustion and emission performance of the substitute fuel used in boiler and diesel engine were studied.1. The physical and chemical characteristics of the waste vegetable oil and the components of fatty acid were studied. The results showed that the components of waste vegetable oil and the substitute fuel were very similar.2. During the physical processing experiment, the ceramic membrane filtering technology and super wave technique were used and the best condition of ceramic membrane filtering technology was obtained. Under this condition the viscidity-temperature characteristics was studied and the curve of viscidity-temperature characteristics was got. The result also showed that the condition of the super wave intensity 47 W/cm2 and the treating time 32min was the best one to reduce viscidity of the waste vegetable oil.3. During the interchange transesterification of the waste vegetable oil, the fatty acids methyl ester yield was 92.6%. When the methanol and oil ratio was 6.5:1, the alkaline catalyst density was 1.27% and the reaction time was 24mins. When putting excessive waste vegetable oil, the interchange transesterification presented for pseudo-first-order reaction, the reaction equation was - dcM /dt = Kc1.2M and the activation energy was 52.129 kjlmol on the study of transforming mechanism and the reacting kinetics. The digital model of substitute fuel produced from wasted oil was established by the three-factor quadratic regression orthogonal rotary method and the model was y = -2.023+10.576%, +88.735x2 +0.3328x3 -2x1x2 -0.0075x1x3 -0.0125x2x3 -0.604x12 -29.775x22 -0.00551x32. Also the best technics condition was gained which provided the theory base for industrial production of the substitute fuel.4. Analyzing the components and the physical and chemical characteristics of the substitute fuel we found that cetane indices of the fuel was higher in combustion characteristics; the flash point was above 100C and the density was higher than 0# diesel by 10% in physical characteristics; the fuel was mainlyfrom fatty acids methyl ester with 18 carbon and 16 carbon and its molecular structure was similar to the optimal diesel substitute (C19H36O2). So we could conclude the substitute had better kindling performance and safety.5. Blazed in the boiler, the substitute fuel had lower emission of CO and CO2 than the diesel fuel by 30%~70% and no sulfide, lower nitrogen oxide exhaust by 85%. Combustion efficiency of the substitute fuel can be 68%, which was higher than that of the diesel fuel by 10%. The exhaust temperature of substitute fuel can be 600癈, which was higher than the diesel fuel by 7%. The results were important to the glasshouse getting higher heat and the boiler using in heated air-drying.6. When tested in the engine test-bed with rated power and rated rotate speed, the combustion output power of the substitute fuel was equal to that of the diesel fuel. But the thermal efficiency of the former was lower than that of the latter by 6%~14%. Compared the exhaust temperature, the smoke opacity, the CO2) CO, NOX and HC density of the substitute fuel with that of the diesel fuel under different load, we can found that the former's exhaust temperature, the smoke opacity and the density of CO2 , CO , HC was lower than the latter's by 10-25C, 50-80%, 10-15%, 10-18%, 47-61% respectively. But the density of NOx was higher by 8%. These results can decelerate the crisis...
|
PDF Full Text Request