Method and reaction system for liquid phase cycling hydrotreatment

The invention discloses a method and a reaction system for liquid phase cycling hydrotreatment. In the method, part of a liquid phase product after the hydrotreatment is mixed with fresh raw oil in a cycling mode to form a liquid phase material; hydrogen is mixed into the liquid phase material; the hydrogen mixed amount is 1 to 20 times that of the dissolved hydrogen which makes the reaction system saturated under a reaction condition; the liquid phase material mixed and dissolved with the hydrogen is put into a reactor; a hydrogenation catalyst bed is arranged in the reactor and is immersed in the liquid phase material; the upper part of the reactor is provided with a gas phase space; a pressure control system communicated with the gas phase space is arranged on the reactor and controls the pressure in the reactor by controlling the gas exhaust quantity; and the liquid phase material dissolved with the hydrogen is put into the hydrogenation catalyst bed of the reactor to perform hydrogenation reaction. Compared with the prior art, the method ensures that the liquid phase cycling hydrotreatment can be controlled and operated stably, and obtain an ideal reaction effect.