Flow properties of biodiesel at low temperature and its improvement

Flow properties of biodiesel at low temperature were studied by means of gas chromatography-mass (GC-MS), cold filer plugging point tester, the solution crystallization theory and the electronic effect theory. According to bilayer crystallization mechanism of biodiesel, three approaches for reducing cold filer plugging point (CFPP) of biodiesel were put forward: (i) blending with petrodiesel; (ii) treating with cold flow improver additives; and (iii) crystallization fractionation. The study shows that CFPPs of palm methyl ester (PME) and -10 petrodiesel (-10PD) are 8℃ and -7℃, respectively. PME blending with -10PD decreases the CFPP of -10PD / PME to -12℃. A eutectic mixture is formed by -10PD and PME, with its CFPP -12℃, and the range of PME blending ratio is 5vol %-20 vol%. Adding 1.0 vol% Flow Fit, 1.5 vol% Flow Fit K and 1.5 vol% T818 additive decreases the CFPP of PME to 3℃, 2℃ and 3℃, respectively. Crystallization fractionation decreases the CFPP of PME to 0℃, and its yield is 68.2 vol%. The study provides technical support for using biodiesel in cold region.