Method for preparing biodiesel from nigre

Abstract

The invention discloses a method for preparing biodiesel from nigre, comprising the following steps of: preparing acid oil; refining the acid oil, adding softening water in the acid oil, and stirring to form a liquid separation layer, and dehydrating via a film evaporator to obtain standard raw oil; and performing esterification reaction, mixing the standard raw oil with methanol and concentrated sulphuric acid, heating, reacting in environments of reflux with methanol in large amount and full stirring and mixing, stopping the reaction when the content of methyl ester is greater than or equal to 96%, and distilling out the methanol to obtain crude biodiesel; and refining the biodiesel. According to the invention, the acid oil is prepared from nigre by an alcoholysis method, so that an acidification speed can be remarkably accelerated, the quality of the acid oil can be improved, and energy consumption can be reduced; simultaneously, the reaction time is effectively shortened by virtue of a membrane separation technology, and the time of common acid catalytic esterification reaction is reduced to 2-3h from 5h, so that the energy consumption is reduced; and moreover, the raw material used in the method disclosed by the invention is nigre which is wide in source and low in price, so that the cost of the acid oil is reduced, and pollution to environment is reduced.

Description

technical field [0001] The invention belongs to the field of biodiesel preparation, in particular to a method for preparing biodiesel from soapstock. Background technique [0002] Biodiesel, namely fatty acid methyl ester, is a clean and renewable energy source. It is a kind of liquid fuel made from a variety of natural oils and methanol (or other alcohols) through chemical reaction. It is an environmentally friendly energy source. The economic feasibility of producing biodiesel mainly depends on the raw materials. Not only does it require sufficient resources, but it also requires low prices in order to have economic competitiveness. The raw materials used cannot compete with residential edible oils. [0003] 75% of the production cost of diesel alternative fuels is the cost of raw materials. High prices are the main obstacle to the commercialization of alternative fuels. Seeking cheap raw materials has become the key to the practicality of diesel alternative fuels. Soapst...

AI Technical Summary

Problems solved by technology

Soapstock (also known as oil sludge) is produced during the production of edible oils and fats from raw materials such as rubber seeds, rice bran, corn germ, and cottonseed. The discharge of these soapstocks pollutes the environment and wastes resources on the one hand.