Method of manufacturing renewable diesel from biological feedstock

A system for producing a renewable fuel comprising C10-C18 alkanes, the system comprising:

• a first reaction chamber configured to:
• receive a primary feedstock and up to 50% water under counter-current flow conditions, the primary feedstock comprising biologically-derived triglycerides and catalyst poisons;
• hydrolyze the primary feedstock for at least an hour to form a hydrolysis effluent comprising (i) an aqueous solution comprising glycerol and a first portion of the catalyst poisons and (ii) an intermediate feedstock comprising free fatty acids and a second portion of the catalyst poisons, wherein the first reaction chamber is maintained at a temperature between 250° C. and 270° C. and a pressure between 700 psig and 900 psig;
• and
• separate the intermediate feedstock and the aqueous solution;
• a distillation column configured to:
• receive the intermediate feedstock;
• and
• distill the intermediate feedstock at an absolute pressure under 700 mm Hg to obtain a purified intermediate feedstock comprising free fatty acids and a bottom stream containing unreacted triglycerides, diglyceride, monoglyceride, free fatty acids, and at least a portion of the second portion of the catalyst poisons;
• a second reaction chamber comprising a metallic catalyst and configured to hydrotreat the purified intermediate feedstock by contacting the purified intermediate feedstock with hydrogen to produce the renewable fuel comprising C10-C18 alkanes, wherein the hydrotreating is carried out at a temperature between 200° C. and 350° C. and a pressure between 300 and 1000 psig;
• a purification unit configured to:
• remove the at least the portion of the second portion of the catalyst poisons from the bottom stream to form a recycle stream containing unreacted triglycerides, diglyceride, monoglyceride, and free fatty acids;
• and
• direct the recycle stream to the first reaction chamber.