METHOD OF TREATMENT OF SYNTHETIC FISCHER-TROPSCH OIL FOR PRODUCING DIESEL FUEL BASE AND METHOD OF CALCULATING DEGREE OF CRACKING OF WAX FRACTION

摘要

A method of processing Fischer-Tropsch synthetic oil to manufacture a diesel fuel base stock, the method comprising: (a) fractionating, in a fractionator, Fischer-Tropsch synthetic oil obtained by a Fischer-Tropsch synthesis method into at least two fractions of a middle fraction containing a component having a boiling point range corresponding to diesel fuel oil and a wax fraction containing a wax component heavier than the middle fraction; (b) bringing the wax fraction into contact with a hydrocracking catalyst in a hydrocracking reactor to obtain a hydrocracked product; (c) separating a gas component from the hydrocracked product to produce hydrocracked oil in a gas-liquid separator disposed in the rear of the hydrocracking reactor in the step (b); (d) measuring the composition of the gas component seperated in the step (c); (e) calculating a cracking rate in the hydrocracking reaction based on the composition of the gas component measured in the step (d); and (f) controlling an operation condition of the hydrocracking reactor so that the cracking rate calculated in the step (e) agrees with an objective cracking rate. Also provided is a method of calculating a cracking rate in hydrocracking a wax fraction obtained by fractionating Fischer-Tropsch synthetic oil in a fractionator.