Crude biodiesel refining method

Abstract

The present invention provides a novel crude biodiesel refining method, which comprises: placing crude biodiesel in a crystallizer, adding a conditioning agent, and uniformly conducting mixing; conducting cooling to a cooling crystallization temperature from room temperature at a certain cooling rate, and maintaining a certain crystallization time; allowing glycerin, a catalyst, residual soap and other impurities to be separated out in a solid phase mode and attached to the wall face of the cooling structure of a crystallizer; and introducing biodiesel existing in a liquid phase form into a rectifying tower, and obtaining refined biodiesel at the top of the tower. According to the refining method, a non-polar solvent is added, the content of residual impurities such as glycerin, a catalyst and residual soap in the crude biodiesel is greatly reduced through cooling crystallization, and standard requirements are met through further rectification; a washing process is not needed, and wastewater discharge is avoided; control of a high-vacuum rectification process is facilitated, the separation load of the rectification process is reduced, and the service life of filler in a rectification tower is prolonged; and meanwhile, the quality of the biological asphalt as a byproduct is improved.

Description

technical field [0001] The invention belongs to the technical field of biodiesel, and in particular relates to a method for refining crude biodiesel. Background technique [0002] As a clean and renewable energy source, biodiesel has a high cetane number, good degradation performance, and its physical properties are very close to those of petrochemical diesel. It is one of the important alternative fuels for petrochemical diesel. Vigorously developing biodiesel will contribute to sustainable economic development and promote energy substitution. It is of great strategic significance to reduce environmental pressure. [0003] Biodiesel can be obtained through esterification and transesterification of animal and vegetable oils, and its main components are fatty acid alkyl esters, such as fatty acid methyl esters. The reaction products obtained after the reaction include fatty acid methyl esters, glycerin, water, unreacted methanol, catalysts, and a small amount of soap generat...

AI Technical Summary

Problems solved by technology

[0004] In order to remove impurities during the washing process, a large amount of water is usually required to be washed repeatedly, resulting in the discharge of a large amount of biodiesel wastewater, and the crude biodiesel after washing needs to be heated and dehydrated again, which increases the difficulty and cost of subsequent treatment.

In order to avoid the discharge of a large amount of complex and difficult-to-treat wastewater, the stratified upper liquid phase fatty acid methyl ester can also be directly refined by vacuum distillation, but in the actual production process, it is usually necessary to set 2-3 Refining treatment in one tower, the control accuracy and difficulty of the vacuum rectification tower are very high, and the bio-asphalt extracted from the tower kettle contains impurities such as glycerin, catalyst and residual soap, which affects the quality of by-products

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