OPERATION METHOD OF MIDDLE DISTILLATE HYDROTREATING REACTOR, AND MIDDLE DISTILLATE HYDROTREATING REACTOR

There is provided an operation method of a middle distillate hydrotreating reactor which hydrotreats and hydroisomerizes a middle distillate including components of a boiling point range equivalent to gas oil among FT synthesis hydrocarbons synthesized by the Fisher-Tropsch synthesis reaction, the operation method comprising the steps of: bringing the middle distillate into contact with a catalyst to hydrotreat and hydroisomerize the middle distillate to produce hydrotreated middle distillate; measuring the cloud point of the hydrotreated middle distillate flowing out from the middle distillate hydrotreating reactor; and controlling the operating conditions of the middle distillate hydrotreating reactor so that the cloud point comes to a predetermined target value.