Device and method of producing ultra-low sulfur biodiesel

A device for producing ultra-low sulfur biodiesel, wherein the device for producing ultra-low sulfur biodiesel is a two-stage processing device, which comprises a two-stage purification unit, a two-stage enzyme reaction unit, and a two-stage distillation unit, and further comprises a decompression rectification unit according to the production process;

• and wherein
• the purification unit comprises a raw material storage tank, a heater, a purification tower, a mixer, and a centrifuge that are connected in order through a pipeline;
• a raw material pump is installed on the pipeline between the raw material storage tank and the heater;
• an external pipe communicated with the heat source is installed on the heater;
• a circulation pump is installed on the pipeline between the heater and the purification tower;
• the lower part of the purification tower is communicated with a wastewater tank, the upper part of the purification tower is communicated with the mixer, and an external pipe communicated with high-pressure methanol water is installed on the mixer;
• the mixer is communicated with the centrifuge, the bottom of the centrifuge is communicated with the wastewater tank, and the upper part of the centrifuge is communicated with a primary elution raw material storage tank;
• the device structure and the arrangement of the two-stage purification unit are the same;
• the elution raw material storage tank of a primary purification unit is the initial raw material storage tank of a secondary purification unit;
• the enzyme reaction unit comprises a methanol storage tank, and a immobilized enzyme reaction bed, a crude glycerol storage tank, a high-speed centrifuge, and a crude methyl ester storage tank connected together in order through a pipeline;
• the elution raw material storage tank of the secondary purification unit is communicated with the immobilized enzyme reaction bed through a pipeline;
• the immobilized enzyme reaction bed is also communicated with the methanol storage tank through a pipeline;
• the immobilized enzyme reaction bed is communicated with the centrifuge, and the centrifuge is communicated with the crude glycerol storage tank and the crude methyl ester storage tank, respectively;
• the two-stage enzyme reaction units share a single methanol storage tank, the methanol storage tank is connected with each of the two-stage immobilized enzyme reaction beds through a pipeline, and a control valve is provided on the pipeline through which the methanol storage tank is communicated with each of the two-stage immobilized enzyme reaction beds;
• the crude methyl ester storage tank of a primary esterification reaction unit is an initial raw material storage tank of a secondary esterification reaction unit;
• the distillation unit comprises a molecular distillation tower and a high-coagulation product storage tank;
• the crude methyl ester storage tank of the secondary esterification reaction unit is communicated with a primary molecular distillation tower in a primary distillation unit through a pipeline, the primary molecular distillation tower is communicated with a primary high-coagulation product storage tank and a secondary molecular distillation unit in a secondary distillation unit, respectively, and the secondary molecular distillation tower is communicated with a secondary high-coagulation product storage tank and a decompression rectification unit, respectively;
• the decompression rectification unit comprises a decompression rectification tower and a tower overhead condenser;
• the decompression rectification tower is communicated with the secondary molecular distillation tower through a pipeline, and a decompression rectification tower bottom circulation pump is installed on this part of the pipeline;
• the bottom of the decompression rectification tower is communicated with a residue storage tank and the top thereof is communicated with a biodiesel product storage tank through a pipeline, and a decompression rectification tower overhead circulation pump is installed on this part of the pipeline;
• the tower overhead condenser is communicated with the decompression rectification tower and the biodiesel product storage tank through a pipeline, respectively;
• and the lower part of the decompression rectification tower is also provided with an external pipe that is communicated with a heat source.