耦合闪蒸的连续超临界甲醇法制备生物柴油

Integration of continuous preparation of biodiesel and separation of methanol under supercritical condition

在耦合闪蒸装置的管式反应器中,以菜籽酸化油为原料,采用超临界甲醇法连续制备生物柴油,同时绝热闪蒸回收甲醇,考察了醇油摩尔比、反应温度、反应压力、反应时间以及闪蒸压力对生物柴油收率、甲醇回收率及气相中甲醇含量的影响。结果显示,在醇油摩尔比35∶1,反应温度300℃,反应压力13 MPa,反应时间600 s的最优条件下,生物柴油收率可达83.1%(以菜籽酸化油质量计);在最优条件及闪蒸压力为常压条件下,闪蒸甲醇回收率可达90.5%,气相中甲醇含量达97.7%;对闪蒸回收的甲醇循环使用5次后,甲醇回收率为86.8%,回收甲醇中甲醇的质量分数为93.7%,该组成的回收甲醇对生物柴油收率无明显影响。

In a tubular reactor coupled with flash vessel,continuous preparation of biodiesel and continuous recovery of methanol via adiabatic flashing were conducted with acidified rapeseed oil as raw material in supercritical methanol.The effects of molar ratio of methanol to oil,reaction temperature,reaction pressure and reaction time on oil conversion were studied.Meanwhile,the effects of the conditions above and flashing pressure on methanol recovery and methanol content in gas phase were also discussed.The results indicated that the yield of biodiesel reached 83.1% under the optimal conditions of molar ratio of methanol to oil 35∶ 1,reaction temperature 300 ℃,reaction pressure 13 MPa and reaction time 600 s.Under the optimal conditions above and atmospheric pressure of flashing pressure,the methanol recovery and the methanol content in gas phase was 90.5%and 97.7%,respectively.After the recovered methanol was recycled for five times,the methanol recovery and the mass fraction of methanol was 86.8% and 93.7%,respectively.The composition of the recovery of methanol had no significant effect on biodiesel yield.