(624d) Simulating the Impact of Distillation Operating Parameters On Energy Requirement for Methanol Separation From Biodiesel

Biodiesel is a wonderful replacement to conventional petro-diesel fuel, which can be produced from a renewable domestic resource. In biodiesel production process, oil or animal fat (Triglyceride) react with a primary alcohol in presence of a catalyst to give the corresponding alkyl esters of the fatty acid mixture that is found in the parent vegetable oil or animal fat. Methanol is a widely used primary alcohol for biodiesel production. After the biodiesel process is complete, a lot of methanol is available for recovery and reuse. To meet ASTM D6751 or EN 14214 standards the removal of excess methanol becomes a vital step. Residual methanol in the biodiesel fuel is a major environmental and health safety issue.  Methanol is toxic, and the emission of excess methanol from the use of biodiesel can be hazardous for our life and environment. Excess methanol can also make the fuel flammable and more dangerous to handle and store. Besides, excess methanol may corrode metal components of engine. For these reasons, most conventional biodiesel manufacturers waste a lot of unused methanol through washing the final product. A simulation study has been done using ASPEN PLUS^TM for excess methanol separation in continuous biodiesel production process using a distillation column. The feedstock used for biodiesel production was triolein containing 15% free fatty acid (as oleic acid). The special attention was devoted to the effect of different alcohol to oil ratio and important design and operating parameters (reflux ratio, operating pressure, number of stages etc.) of distillation column on excess methanol separation from the product. Analysis of simulation results shows that for a certain distillation operating condition and reaction parameters it is possible to separate around 95-98% of excess methanol before phase separation of biodiesel and glycerol, although for high alcohol to oil ratio the energy requirement increases exponentially.