Patent attributes
The present invention relates to a method for preparing low-sulfur biodiesel. The method includes the following steps: subjecting raw crude oil to heat exchange, preheating, glycerol esterification reaction, flashing, cooling, transesterification, dealcoholization, sedimentation, and methyl ester rectification to obtain low-sulfur biodiesel up to the standard, where in the heat exchange process, the raw crude oil exchanges heat with flashed oil to recycle some heat, and glycerol and fatty acids in a distilled product subjected to flashing are reused for the glycerol esterification reaction; the dealcoholization process removes methanol in a system after the transesterification, and refined methanol recycled by methanol rectification is reused for the transesterification reaction; crude glycerol generated in the sedimentation process does not need to be treated and is directly used for glycerol rectification to obtain refined glycerol, and the refined glycerol is reused for the glycerol esterification reaction.
