利用自制设备转化废弃油脂制备生物柴油

Biodiesel production from waste cooking oil using biodiesel conversion equipment

为了满足小型用户就地生产、使用生物柴油的需求,利用自主研发的集成式生物柴油生产设备进行了废弃油脂转化生物柴油加工示范。该设备的反应过程主要包括2个工艺:反应工艺A,反应温度60℃,甲醇加入量10%,浓硫酸加入量1%,反应时间5h;反应工艺B,反应温度60℃,浓硫酸加入量0.1%,甲醇加入量4%,反应5h后加入NaOH0.8%,甲醇12%,继续反应1.5h。针对不同品质的废弃油脂分别采用不同的工艺路线:当废弃油脂酸值及含水率较大时,先采用A工艺,降低酸值和含水率,再进行B工艺;当废弃油脂酸值及含水率较小时,仅采用B工艺。设备的工艺路线适用于不同酸值的废弃油脂,生物柴油产率达95%以上,产品符合国家标准。

In the last few years, biodiesel has emerged as one of the most potential renewable energy to replace current petrol-derived diesel. It is a renewable, biodegradable and non-toxic fuel. Biodiesel production using waste cooking oil （WCO） is receiving increasing attention. However, the large range of free fatty acids （FFA） content has become the main drawback for the conversion of WCO into biodiesel with single procedure, and the lack of government management of WCO makes it difficult to collect feedstock in large scale, which reduces the economic feasibility of biodiesel. In order to satisfy the requirement for producing biodiesel in miniature, efficient biodiesel conversion from WCO with high FFA was achieved via a home-made biodiesel conversion equipment. There were four sorts of feedstocks for biodiesel production, including fried chicken oil, WCO1, WCO2 and WCO3, whose acid value were 10.2, 30.8, 45.6 and 80.0 mg/g, respectively. The reaction process was involved two procedures called A and B. The procedure A was an esterification reaction to decrease the acid value and moisture of feedstocks. It was carried out with reaction temperature 60℃, methanol 10%, H2SO4 1%, reaction time 5 h, and then some byproducts were separated from the reaction mixture. The conversion rate of FFA of feedstocks was above 90% through procedure A. An orthogonal design was applied to optimize main performance parameters for the transestrification reaction of procedure B. The procedure B started with an acidic catalysis with reaction temperature 60℃, methanol 4%, H2SO4 0.1%, reaction time 5 h, followed by a basic catalysis with methanol 12%, NaOH 0.8%, reaction time 1.5 h, and then some byproducts were separated from the reaction mixture. Final product was obtained through water washing using 70 L of water. The separation of byproducts and water from the mixture reaction was accomplished by electrostatic layered process which decreased the separation time from 12 h to 1 h. The procedure B was adopted for WCO with low acid value and moisture content. With high acid value and moisture content, procedure A was used to reduce acid value, and then procedure B was utilized to complete biodiesel conversion. The equipment with unique reaction procedure can produced biodiesel from WCO with large range of acid values. The output of equipment was about 400 L/d. The yields of biodiesel from fried chicken oil, WCO1, WCO2 and WCO3 were 97.6%, 95.9%, 95.4% and 95.5%, respectively. The quality indexes of biodiesel production from fried chicken oil and WCO2 met GB／T20828-2007 except oxidation stability and total glycerin content. The oxidation stability was lower than the standard value, which could be solved by adding antioxidant. The total glycerin content was slight higher than the standard value, which could be solved by prolonging separation time. The study provided a new approach for producing biodiesel from WCO in small scale.