Medium-pressure hydrocracking process

Abstract

The present invention discloses a medium-pressure hydrocracking process able to simultaneously produce products such as qualified gasoline, kerosene, diesel, etc.. Based on the prior medium-pressure hydrocracking process, the present invention uses a fresh hydrogen resource and a hydrosaturation catalyst with reduced metals of group VIB and/or group VIII as the active components to selectively and deeply hydrosaturate the jet fuel and/or diesel cuts derived in the medium-pressure hydrocracking, thereby allowing the quality of these cut fractions to meet the requirement of the specifications. In the present invention, a quite favorable reaction environment is created for the deep hydrosaturation of the jet fuel and/or diesel cuts with an extremely low investment by reasonable combination of the medium-pressure hydrocracking process flow, full reliance on the medium-pressure hydrocracking,, and addition of an ultra-low-pressure hydrosaturation reactor. This makes it possible to not only simultaneously produce products such as qualified gasoline, kerosene, diesel, etc., but also further lower the operation pressure of the hydrocracking since the requirement for the quality of such products as the hydrocracked jet fuel, diesel, etc. is broadened.

What is claimed is:  
     
         1 . A medium-pressure hydrocracking process, comprising the steps of contacting feed oil with a hydrocracking catalyst in a hydrocracking system under a medium pressure and hydrocracking conditions; separating the hydrocraking reaction product into a vapor fraction which is recycled to the hydrocracking system as recycling hydrogen, and a liquid fraction which is further separated in a separation system to produce distillates including jet fuel and/or diesel (hereinafter referred to as hydrocracked jet fuel and/or diesel) cuts; feeding a part or all of the hydrocracked jet fuel and/or diesel cuts into a hydrosaturation system where the cuts come into contact with a hydrosaturation catalyst and react with fresh hydrogen under hydrosaturation conditions; separating the hydrosaturation reaction product into a hydrogen-containing vapor which enters into the hydrocracking system as make-up hydrogen, and jet fuel and/or diesel (hereinafter referred to as the hydrosaturated jet fuel and/or diesel) which enter into a separation system for processing.  
     
     
         2 . The process according to  claim 1 , wherein a part or all of the hydrocracked jet fuel cut enters into a hydrosaturation system for processing.  
     
     
         3 . The process according to  claim 1 , wherein a part or all of the hydrocracked diesel cut enters into a hydrosaturation system for processing.  
     
     
         4 . The process according to  claim 1 , wherein a part or all of the hydrocracked jet fuel and diesel cuts enter into a hydrosaturation system for processing.  
     
     
         5 . The process according to  claim 1 , wherein all of the hydrocracked jet fuel and/or diesel cuts enter into a hydrosaturation system for processing, and the hydrosaturated jet fuel and/or diesel enter into an individual separation system for processing, which then separately leaves the equipment as products.  
     
     
         6 . The process according to  claim 1 , wherein a part of the hydrocracked jet fuel and/or diesel cuts enter into a hydrosaturation system for processing, and the hydrosaturated jet fuel and/or diesel cuts enter into an individual separation system for processing, which then mixes with the other part of the corresponding hydrocracked jet fuel and/or diesel cuts and separately leaves the equipment as products.  
     
     
         7 . The process according to  claim 1 , wherein both the liquid fraction of the hydrocracking reaction product and the hydrosaturated jet fuel and/or diesel enter the same separation system for fractionation together, and a part of the separated jet fuel and/or diesel cuts enter into the hydrosaturation system for processing, and the remainder leaves the equipment as products.  
     
     
         8 . The process according to  claim 1 , wherein said hydrosaturation catalyst is a reduced catalyst with one or more metals of Groups VIB and/or VIII of the Periodic Table as the hydrogenation components.  
     
     
         9 . The process according to  claim 1 , wherein the hydrocracking reaction is carried out under a pressure of 4.0-10.0 MPa, at a temperature of 360-400° C., with a hydrogen/oil volume ratio of 800:1-1500:1 and a liquid hourly volume space velocity of 0.5-1.5 h −1 .  
     
     
         10 . The process according to  claim 1 , wherein the hydrosaturation reaction is carried out under a pressure of 0.5-3.0 MPa, at a temperature of 100-280° C., with a hydrogen/oil volume ratio of 200:1-1000:1, and a liquid hourly volume space velocity of 1.0-6.0 h 31 1 .  
     
     
         11 . The process according to  claim 1 , wherein said fresh hydrogen comes from a hydrogen-production system or the pipe net of the refinery and contains no such impurities as H 2 S and NH 3 , which is used directly in the process without being additionally pressurized.  
     
     
         12 . The process according to  claim 8 , wherein said one or more metals is/are selected from the group consisting of Pt, Ni, and Pd.  
     
     
         13 . The process according to  claim 9 , wherein said pressure is 4.0-8.0 MPa.  
     
     
         14 . The process according to  claim 10 , wherein said temperature is 100-250° C., and said pressure is 1.0-2.0 MPa.  
     
     
         15 . The process according to  claim 7 , wherein the weight ratio of said jet fuel and/or diesel distillate entering into the hydrosaturation system to those leaving the system as jet fuel and/or diesel products is 1:6-6:1.