Study on cold flow properties of waste oil biodiesel and improvement

Abstract

The cold flow properties of waste oil biodiesel (WME) were studied by gas chromatography-mass spectrometry (GC-MS), multifunctional low temperature tester, differential scanning calorimetry (DSC) and solution crystallization theory. Three approaches for reducing cold filter plugging point (CFPP) of WME were investigated: crystallization fractionation, blending with winter petrodiesel and treating with cold flow improver (CFI) additives. A good correlation model was proposed for prediction CFPP by WME blending ratio. The study shows that the WME was mainly composed of fatty acid methyl esters (FAME): C 14∶0 –C 22∶0 , C 16∶1 –C 22∶1 , C 18∶2 and C 18∶3 . The mass fraction of saturated fatty acid methyl esters (SFAME) and unsaturated fatty acid methyl esters (UFAME) was 31.04% and 64.51%, respectively. The CFPP of WME was 3 °C. Crystallization fractionation and blending with −10 petrodiesel (−10PD) decreased the CFPP to −2 and −12 °C respectively. Treating with CFI additives (volume fraction ≤ 0.5%) decreased the CFPP of WME and WME/−10PD to −1 and −26 °C, respectively. This study has effectively improved cold flow properties of WME and provided guide for using WME during cold weather.