多频超声反应槽连续强化酸化油酯交换制备生物柴油研究

以平均酸值高达33.07 mgKOH/g不可食用的廉价酸化油为原料,利用自行设计的多频超声溢流槽连续强化酯交换反应生物柴油生产装置,先后经预酯化、酯交换两步反应,高效、低耗的制备生物柴油。主要考察了室温下物料流量(停留时间)、超声功率、超声频率及组合、KOH用量、醇油物质的量比对酯交换反应的影响及单位产品能耗。结果表明,多频组合超声辐射比单频更有利于生物柴油的制备;预酯化后的油料在流量为25 L/h(物料停留时间为54 min),催化剂(KOH)用量为1.2%(质量分数),醇油物质的量比为6∶1和各反应槽功率为200 W的条件下,甲酯产率达96.83%。50 L废弃酸化油能制得符合国标GB19147—2009的生物柴油48L,整个生物柴油制备过程总耗时和总耗电量仅为8.667 h、5.42 kWh。

Preparation of biodiesel via continuous transesterification in multi-frequency ultrasonic reaction tank

The preparation of biodiesel from inedible low-cost acid oil with a high average acid value(AV) of about 33.07 mgKOH/g via pre-esterification and transesterification processes in a self-designed continuous biodiesel production apparatus assisted by multi-frequency ultrasonic at high efficiency and low energy consumption was investigated. The influences of operating variables including flow rate of material(residence time), ultrasonic power and frequency or combinations, the amount of catalyst, the molar ratio of methanol to oil at ambient temperature and the specific energy consumption on the transesterification reaction were discussed. The results show that multi-frequency ultrasonic irradiation is superior to single-frequency in enhancing biodiesel production process; the yield of fatty acid methyl esters(FAME) about 96.83% is attained with 15-25-35-40 kHz of frequency combination, 200 W of powers, 25 L/h of flow rates of the processed oil (residence time 54 min), 6:1 mol ratio of methanol to oil,and 1.2% KOH (% of acid oil). 50 L waste acid oil can be converted into 48 L biodiesel that meet the standards GB19147-2009, and the overall electric power and time consumptions are about 5.42 kWh and 8.667 h, respectively.