Plant and animal oil and catalytic diesel oil associated hydrogenation process

The invention discloses a plant and animal oil and catalytic diesel oil associated hydrogenation process. The method is as follows: plant and animal oil is mixed with hydrogen, and then the mixture enters into a hydrogenation isomerization reactor for hydrogenfinishing and isomerized condensation point reduction reactions; a reaction effluent enters into a hot high-pressure separator for separation, a hot high pressure liquid separation phase is mixed with catalytic cracking diesel oil, then the mixture enters into a hydrogen mixing tank for hydrogen mixing, and then the mixture enters into a liquid phase hydrogenation reactor for the hydrogenfinishing reaction, and part of the hydrogenfinished diesel oil is cycled to a lower catalyst bed layer of the hydrogenation isomerization reactor. After hydrogenation isomerization condensation point reduction of the plant and animal oil, on one hand, the hydrogen dissolving amount of the liquid phase hydrogenation reactor can be improved, the condensation point is reduced, and the plant and animal oil has a high cetane number, and can make up for the shortage of a deficient cetane number of catalytic diesel oil by catalytic associated hydrogenation. The method broadens the sources of raw materials for diesel oil production of a refinery plant, and provides a way out for processing of poor-quality catalytic diesel oil.