The present invention relates to a method and an apparatus for producing
ultra low sulfur diesel oil through liquid-phase hydrogenation. The apparatus comprises a hydrogenation reactor, a steam stripping separator, a
trickle-
bed reactor, a
gas pipeline, a
heat exchanger 1, an air cooler, a circulation pump, a
heat exchanger 2, a
heat exchanger 3, a cold low-pressure separator and a hot low-pressure separation tank, wherein a catalyst
bed layer and a hot high-pressure separator are arranged inside the
trickle-
bed reactor. According to the present invention, a diesel oil
raw material is subjected to a
hydrogenation reaction in the hydrogenation reactor, the
reaction product is separated in the steam stripping separator to obtain a
liquid product, one part of the
liquid product returns to the hydrogenation reactor, the other part of the
liquid product is mixed with supplemented
hydrogen, the obtained mixture is subjected to a second-stage
hydrogenation reaction in the
trickle-bed reactor, the second-stage
hydrogenation reaction product is directly subjected to second-stage hot high-pressure separation to obtain a liquid product, the obtained liquid product is subjected to heat exchange, and the product being subjected to the heat exchange enters the hot low-pressure separation tank; and the second-stage hydrogenation reactor and the second-stage hot high-pressure separator are additionally arranged, the diesel oil
raw material is subjected to the first-stage hydrogenation, the obtained
raw material is continuously subjected to the deep hydrogenation reaction, and the
sulfur content in the diesel oil being subjected to the two-stage hydrogenation is reduced to less than or equal to 10 ppm so as to improve the quality grade of the diesel oil product.