3.2. Effect of reboiler temperature
From the experiment, the reboiler temperature was varied from85◦C to 120◦C. The effect of the temperature on methyl ester purity can be shown in Fig. 3. After 6 h, the processes turn into steady state. The operation at the temperature of 90◦C provides the high-est ME purity. The temperature of 100◦C and 85◦C give the lower methyl ester purity while the temperature of 120◦C presents the lowest methyl purity. At 8 h from the beginning, the condition of85◦C gives the ME purity is about 73.0% whereas the conditions at90◦C and 100◦C provide ME content purity of 91.6% and 80.8%,respectively, Because at 85◦C, recognizably, there is insufficient methanol mixture vapor and almost no potassium methoxide vapor