Preparation method of biodiesel

Abstract

A preparation method of biodiesel is carried out according to the following steps: pretreatment of waste oils and fats is carried out; esterification reaction is carried out; three raw materials, namely oil, methanol and a cosolvent, are pretreated and measured by a metering pump and are fed into a buffer; the three raw materials are pumped into a continuous tubular reactor; the materials react during the flow process and the process lasts for 1-3h; separation is performed; decolouring is carried out without heating, specifically sending crude methyl esters into a decolouring tank to undergo filtering and decolouring with white clay so as to obtain a product a; and decolouring and degassing are carried out with heating, specifically sending crude methyl esters into the decolouring tank to react with white clay, heating the decolouring tank by the use of steam at the temperature of 70-80 DEG C and keeping the temperature for 1-3h so as to obtain a product b. The preparation method has the following advantages: heating and stirring are not required during the esterification reaction process so as to highly efficiently save energy; the whole process is carried out in the environment of low temperature and normal pressure, thus leading to low energy consumption and high utilization rate and being energy saving and environmentally friendly; and equipment is simple, cost is low, construction cycle is short, and dilatancy is strong.

Description

technical field [0001] The invention relates to the field of new energy, in particular to a method for preparing biodiesel from waste oil, and belongs to the field of biodiesel preparation. Background technique [0002] Biodiesel is a mixed fatty acid methyl ester obtained by esterification of waste oil (mainly composed of triglycerides and higher fatty acids) with methanol. [0003] At present, the preparation process of biodiesel is divided into acid method, alkali method, acid-base method, enzymatic method, supercritical method, etc. according to the different catalytic esterification methods in the reaction process. These methods all include the following two processes: [0004] First, during the esterification reaction, oleyl alcohol has a two-phase immiscibility phenomenon, and it is in a state of upper and lower stratification after standing. Measures need to be taken to expand the contact area between the two, accelerate the reaction rate, and improve the reaction co...

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Problems solved by technology

[0006] In the actual production process, the above two processes often lead to incomplete reaction and unqualified products due to poor handling. Therefore, most production enterprises usually set up a stirring process to promote the reaction and vacuum distillation for product separation. However, these two processes are both high-energy-consuming processes, which not only consume high energy, but also require a large investment, so they are not suitable for widespread use by small-scale diesel production enterprises.

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