Cold Flow Properties Of The Palm Oil Methyl Ester And Its Improvement

In order to alleviate energy shortage and environmental pollution, biodiesel becomes the favorites of most countries with its features of renewable and environmentally friendly. However, saturated fatty acid methyl ester of biodiesel was easy to crystallize at low temperature, which restricting use of biodiesel under the condition of low temperature. Therefore, the cold flow property of biodiesel should be improved. This paper mainly studied the composition of biodiesel, cold flow property and crystallization mechanism of palm oil biodiesel, as well as three mesurements to improve its cold flow property.Firstly, prepared biodiesel with palm oils. The components of biodiesel were analyzed by GC-MS. The study showed that cold filter plugging point of biodiesel increased with the increasing amount and carbon chain length of saturated fatty acid methyl ester, and decreased with the increasing content and unsaturation degree of unsaturated fatty acid methyl ester.Secondly, analyzed cold flow property of PME and petrochemical diesel based on the studying of their composition and molecular structure. Results showed that0#diesel oil(OPD) and-10diesel oil (-10PD) were mainly composed of8-26of normal alkane carbon atoms, and mainly composition of PME was C14～C22FAME, including saturated fatty acid methyl ester (C14:0～C22:0) and unsaturated fatty acid methyl ester (C16:1～C20:1, C18:2and C18:3) with fraction of40.13%and59.57%; The cold filtration point (Cold Filter Plugging Point, CFPP) of OPD、-10PD and PME1were-3,-8and10℃, motion viscosity (40℃) were2.91,2.53and4.91mm2/s.According to the solution crystallization theory and electronic effects theory, the biodiesel crystallization process was that the formation of a supersaturated solution→nucleation of SFAME→crystal growth. Using low temperature microscopy to observe crystallization of PME1under low temperature environment, crystal was regular polygon thin sheet, temperature and cooling rate affected PME1crystal morphology. With temperature decreasing, crystal growed and formed three-dimensional network structure with UFAME in it. The mechanism of biodiesel cold flow improver mainly included:adsorption theory, the theory of eutectic, crystal nucleus function theory, the synergy of crystal nucleus, adsorption and eutectic. Finally, through understanding crystallization mechanism of biodiesel and the low temperature fluidity improvement mechanism, proposed and confirmed three measures to improve the low temperature fluidity of PME:crystallization separation, adding the mixture, adding the cold flow improver. Got PME2-CF from PME2by crystallization separation, which CFPP was0℃, lower8℃than PME2CFPP. Blended PME1with0PD、-10PD and kerosene in different proportion, and studied the cold flow property of PME1/0PD, PME1/-10PD and PME1/kerosene. Research has shown that:(1)With the increase of PME1blend ratio, blending oil CFPP decrease first and then increased. When the PME1blending proportion was less than20%, PME1/0PD, PME1/-10PD and PME1/kerosene fell to the lowest-11、-13and-40℃, respectively, the cold flow property were certain improved;(2)As the PME1blending ratio increasing, the blending oil viscosity also showed a trend of increase, and the the blended oil viscosity was between the mixture and PME1; The blending oil viscosity increased with temperature decreasing, and when the temperature was close to the CFPP, the blended oil viscosity increases sharply, the viscosity-temperature curve was steep;(3)Using regression analysis method to establish the PME1/0PD and PME1/-10PD viscosity-temperature equation;(4)Through treating PME and its blending with three CFI:Flow Fit, Flow Fit K and T818, the cold flow property of PME1and its blended oil all have certain improved. Research showed that the addition of Flow Fit, Flow Fit K and T818(volume fraction<8%o) could reduce the CFPP of PME1from10℃to4℃and reduce the CFPP of PME1/0PD, PME1/-10PD to the lowest-20℃and-26℃respectively.