Integrated hydrotreating hydrodewaxing hydrofinishing process

Abstract

Provided is a three stage hydroprocessing process for producing lubricant base stocks with a stripping/separating zone between the first two hydroprocessing zones and a separating zone following the third hydroprocessing zone. The stripping/separating zone occurs at high pressure and temperature with no disengagement between or following the hydroprocessing zones and without the use of a liquid pump prior to the second hydroprocessing zone. The process pressure is greatest at the entrance to the first hydroprocessing zone. There is also recycle of compressed gaseous effluent from the last separating zone to the stripping zone, the first hydroprocessing zone, the second hydroprocessing zone, and/or the third hydroprocessing zone.

1 . A continuous process for producing lube base stocks comprising:
 a. passing a hydrocarbon feedstock to a first hydroprocessing zone and hydroprocessing the feedstock under first hydroprocessing conditions to form a first hydroprocessed product, said first hydroprocessing zone having a first hydroprocessing catalyst system, temperature and pressure;   b. passing the first hydroprocessed product to a stripping/separating zone;   c. stripping/separating of the first hydroprocessed product of dissolved H 2 S and NH 3  to form a liquid effluent and a sour gas, and subsequently scrubbing the sour gas to remove H 2 S and NH 3  to form a first gaseous effluent;   d. passing the liquid effluent from the stripping/separating zone and at least a portion of the first gaseous effluent to a second hydroprocessing zone and hydroprocessing the liquid effluent under second hydroprocessing conditions to form a second hydroprocessed product, said second hydroprocessing zone having a second hydroprocessing catalyst system, temperature and pressure;   e. passing the second hydroprocessed product to a third hydroprocessing zone and hydroprocessing the liquid effluent under third hydroprocessing conditions to form a third hydroprocessed product, said third hydroprocessing zone having a third hydroprocessing catalyst system, temperature and pressure;   f. passing the third hydroprocessed product to a separating zone and separating the third hydroprocessed product into a second gaseous effluent and liquid products, including one or more lube base stocks;   g. compressing the second gaseous effluent and recycling at least a portion of the compressed second gaseous effluent back to one or more of the first hydroprocessing zone, the stripping/separating zone, the second hydroprocessing zone, or the third hydroprocessing zone,   wherein the process pressure is highest at the entrance to the first hydroprocessing zone, and with the proviso that no liquids pump exists between stripping/separating zone and the second hydroprocessing zone.   
     
     
         2 . The continuous process of  claim 1 , wherein the hydrocarbon feed is chosen from atmospheric gas oils, vacuum gas oils, coker gas oils, hydrocrackates, raffinates, extracts, hydrotreated oils, atmospheric and vacuum resids, deasphalted oils, dewaxed oils, slack waxes, petrolatum, Fischer-Tropsch waxes and mixtures thereof. 
     
     
         3 . The continuous process of  claim 1 , wherein the first hydroprocessing zone is a hydrocracker or a hydrotreater. 
     
     
         4 . The continuous process of  claim 1 , further including at least one heat exchanger between the first hydroprocessing zone and the stripping/separating zone. 
     
     
         5 . The continuous process of  claim 1 , wherein the stripping/separating zone includes a pressure stripper and a flash separator. 
     
     
         6 . The continuous process of  claim 1 , wherein the stripping/separating zone includes a pressure stripper followed by an amine scrubber followed by a water wash tower. 
     
     
         7 . The continuous process of  claim 6 , wherein the amine scrubber uses an amine solution to remove hydrogen sulfide from the sour gas. 
     
     
         8 . The continuous process of  claim 6 , wherein the water wash tower uses water to remove ammonia from the sour gas. 
     
     
         9 . The continuous process of  claim 5  or  6 , wherein the pressure stripper uses at least a portion of the compressed second gaseous effluent for stripping. 
     
     
         10 . The continuous process of  claim 1 , further including at least one heat exchanger between the stripping/separating zone and the second hydroprocessing zone. 
     
     
         11 . The continuous process of  claim 1 , wherein the second hydroprocessing zone is a hydrodewaxer or a hydrocracker. 
     
     
         12 . The continuous process of  claim 11 , wherein the second hydroprocessing zone uses at least a portion of the compressed second gaseous effluent. 
     
     
         13 . The continuous process of  claim 1 , wherein the third hydroprocessing zone is a hydrofinisher or a hydrodewaxer. 
     
     
         14 . The continuous process of  claim 13 , wherein the hydrofinisher uses at least a portion of the compressed second gaseous effluent. 
     
     
         15 . The continuous process of  claim 1 , further including at least one heat exchanger between the second hydroprocessing zone and the third hydroprocessing zone. 
     
     
         16 . The continuous process of  claim 1 , further including at least one heat exchanger between the third hydroprocessing zone and the separating zone. 
     
     
         17 . The continuous process of  claim 1 , wherein the separating zone includes a flash separator. 
     
     
         18 . The continuous process of  claim 1 , further including purging at least a portion of the second gaseous effluent from the process. 
     
     
         19 . The continuous process of  claim 1 , wherein the tube base stock is chosen from Group I, Group II and Group III. 
     
     
         20 . The continuous process of  claim 1 , wherein the first hydroprocessing zone catalyst system is chosen from Ni/Mo, Co/Mo, Ni/W and combinations thereof. 
     
     
         21 . The continuous process of  claim 1 , wherein the second hydroprocessing zone catalyst system includes a molecular sieve chosen from ZSM-5, ZSM-22, ZSM-23, ZSM-35, ZSM-48, SAPO-11, SAPO-41 and combinations thereof. 
     
     
         22 . The continuous process of  claim 1 , wherein the third hydroprocessing zone catalyst system is chosen from Ni/Mo, Ni/W or Pd and/or Pt, MCM-41, MCM-48, MCM-50 and combinations thereof.