Patent Publication Number: US-7708877-B2

Title: Integrated heavy oil upgrading process and in-line hydrofinishing process

Description:
This application is a Continuation-In-Part of co-pending application Ser. No. 11/305,377, Filed Dec. 16, 2005, Ser. No. 11/305,378, filed on Dec. 16, 2005, and Ser. No. 11/303,425, filed Mar. 20, 2006. 
    
    
     FIELD OF THE INVENTION 
     The instant invention relates to a process for upgrading heavy oils using a slurry catalyst composition, followed by hydrofinishing. 
     BACKGROUND OF THE INVENTION 
     There is an increased interest at this time in the processing of heavy oils, due to larger worldwide demand for petroleum products. Canada and Venezuela are sources of heavy oils. Processes which result in complete conversion of heavy oil feeds to useful products are of particular interest. 
     The following patents, which are incorporated by reference, are directed to the preparation of highly active slurry catalyst compositions and their use in processes for upgrading heavy oil: 
     U.S. Ser. No. 10/938,202 is directed to the preparation of a catalyst composition suitable for the hydroconversion of heavy oils. The catalyst composition is prepared by a series of steps, involving mixing a Group VIB metal oxide and aqueous ammonia to form an aqueous mixture, and sulfiding the mixture to form a slurry. The slurry is then promoted with a Group VIII metal. Subsequent steps involve mixing the slurry with a hydrocarbon oil and combining the resulting mixture with hydrogen gas and a second hydrocarbon oil having a lower viscosity than the first oil. An active catalyst composition is thereby formed. 
     U.S. Ser. No. 10/938,003 is directed to the preparation of a slurry catalyst composition. The slurry catalyst composition is prepared in a series of steps, involving mixing a Group VIB metal oxide and aqueous ammonia to form an aqueous mixture and sulfiding the mixture to form a slurry. The slurry is then promoted with a Group VIII metal. Subsequent steps involve mixing the slurry with a hydrocarbon oil, and combining the resulting mixture with hydrogen gas (under conditions which maintain the water in a liquid phase) to produce the active slurry catalyst. 
     U.S. Ser. No. 10/938,438 is directed to a process employing slurry catalyst compositions in the upgrading of heavy oils. The slurry catalyst composition is not permitted to settle, which would result in possible deactivation. The slurry is recycled to an upgrading reactor for repeated use and products require no further separation procedures for catalyst removal. 
     U.S. Ser. No. 10/938,200 is directed to a process for upgrading heavy oils using a slurry composition. The slurry composition is prepared in a series of steps, involving mixing a Group VIB metal oxide with aqueous ammonia to form an aqueous mixture and sulfiding the mixture to form a slurry. The slurry is then promoted with a Group VIII metal compound. Subsequent steps involve mixing the slurry with a hydrocarbon oil, and combining the resulting mixture with hydrogen gas (under conditions which maintain the water in a liquid phase) to produce the active slurry catalyst. 
     U.S. Ser. No. 10/938,269 is directed to a process for upgrading heavy oils using a slurry composition. The slurry composition is prepared by a series of steps, involving mixing a Group VIB metal oxide and aqueous ammonia to form an aqueous mixture, and sulfiding the mixture to form a slurry. The slurry is then promoted with a Group VIII metal. Subsequent steps involve mixing the slurry with a hydrocarbon oil and combining the resulting mixture with hydrogen gas and a second hydrocarbon oil having a lower viscosity than the first oil. An active catalyst composition is thereby formed. 
     SUMMARY OF THE INVENTION 
     A process for the hydroconversion of heavy oils with a slurry which results in almost complete removal of sulfur or nitrogen from the final product, said process employing at least two upflow reactors in series with a separator optionally located in between each reactor, said process comprising the following steps:
         (a) combining a heated heavy oil feed, an active slurry catalyst composition and a hydrogen-containing gas to form a mixture;   (b) passing the mixture of step (a) to the bottom of the first reactor, which is maintained at slurry hydroconversion conditions, including elevated temperature and pressure;   (c) removing a vapor mixture containing product, gases, unconverted material and slurry catalyst from the top of the first reactor and passing it to a first separator;   (d) in the first separator, removing a vapor stream comprising product and gases overhead to a lean oil contactor and passing a liquid bottoms material, comprising unconverted material and slurry catalyst, to the bottom of the second reactor, which is maintained at hydroconversion conditions, including elevated temperature and pressure;   (e) removing a vapor mixture containing product, gases, unconverted material and slurry catalyst from the top of the second reactor and passing it to a second separator;   (f) in the second separator, removing a vapor stream comprising product and gases overhead to the lean oil contactor and passing a liquid bottoms material, comprising unconverted material and slurry catalyst to further processing;   (g) contacting the stream comprising product and gases countercurrently with lean oil in a lean oil contactor wherein entrained catalyst and any unconverted material is removed by contact with a lean oil which exits as bottoms while products and gases are passed overhead;   (h) passing the overhead material of step (g) to a hydroprocessing unit for the removal of sulfur and nitrogen.       

     The slurry upgrading process of this invention converts nearly 98% of vacuum residue to lighter products (in the boiling range below 1000 F). Some of these products require further processing due to their high nitrogen, high sulfur and high aromatics content, as well as low API. The instant invention employs hydrofinishing downstream of the slurry upgrading process, resulting in almost complete removal of sulfur and nitrogen from the final product. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURE 
       The FIGURE depicts a process scheme of this invention which employs three reactors, followed by a hydrofinishing reactor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The instant invention is directed to a process for catalyst activated slurry hydrocracking, as depicted in the Figure. Stream  1  comprises a heavy feed, such as vacuum residuum. This feed enters furnace  80  where it is heated, exiting in stream  4 . Stream  4  combines with a hydrogen containing gas(stream  2 ), and a stream comprising an active slurry composition(stream  23 ), resulting in a mixture(stream  24 ). Stream  24  enters the bottom of the first reactor  10 . Vapor stream  5  exits the top of the reactor and comprises products, gases, slurry, and unconverted material. Stream  5  passes to hot high pressure separator  40 , which is preferably a flash drum. A vapor stream comprising products and gases is removed overhead as stream  6 . Stream  6  is passed to a lean oil contactor for further processing. Liquid stream  7  is removed through the bottom of the separator  40 . Stream  7  contains slurry in combination with unconverted oil. 
     Stream  7  is combined with a gaseous stream comprising hydrogen (steam  15 ) to create stream  25 . Stream  25  enters the bottom of second reactor  20 . Vapor stream  8 , comprising products, gases, slurry and unconverted material, exits the second reactor overhead and passes to separator  50 , which is preferably a flash drum. Products and gases are removed overhead as stream  9  and passed to the lean oil contactor for further processing. Liquid stream  11  is removed through the bottom of the flash drum. Stream  11  contains slurry in combination with unconverted oil. 
     Stream  11  is combined with a gaseous stream comprising hydrogen (steam  16 ) to create stream  26 . Stream  26  enters the bottom of third reactor  30 . Stream  12 , which exits third reactor  30  passes to separator  60 , preferably a flash drum. Product and gases are removed overhead from separator  60  as stream  13 . Liquid stream  17  is removed through the bottom of the separator  60 . Stream  17  comprises slurry in combination with unconverted oil. A portion of this stream may be drawn off through stream  18 . 
     Overhead vapor streams  6 ,  9  and  13  create stream  14 , which passes to lean oil contactor  70 . Stream  22 , containing a lean oil such as vacuum gas oil, enters the top portion of lean oil contactor  70  and flows downward. (1) removing any possible entrained catalyst and (2) reducing heavy materials(high boiling range oil including small amounts of vacuum residue). Products and gases (vapor stream  21 ) exit lean oil contactor  70  overhead, while liquid stream  19  exits at the bottom. Stream  19  comprises a mixture of slurry and unconverted oil. Stream  19  is combined with stream  17 , which also comprises a mixture of slurry and unconverted oil. Fresh slurry is added in stream  3 , and stream  23  is created. Stream  23  is combined with the feed to first reactor  10 . 
     Stream  21  enters steam exchanger (or generator)  90 , for cooling prior to hydrofinishing. The purpose of the steam exchanger is to control the hydrofinisher reactor inlet temperature as needed. Stream  21  enters the top bed of the hydrofinisher  100 , a fixed bed reactor, preferably having multiple beds of active hydrotreating catalyst. Hydrogen (stream  27 ) is inserted as interbed quench if multiple beds are used. Hydrofinished product is removed as stream  28 . 
     The hydrofinishing unit further refines products from the slurry upgrader to high quality products by removing impurities and stabilizing the products by saturation. Greater than 99 wt % sulfur and nitrogen removal may be achieved. Reactor effluent is cooled by means of heat recovery and sent to the product recovery section as in any conventional hydroprocessing unit. Conditions for hydrofinishing hydrocarbons are well known to those of skill in the art, Typical conditions are between 400 and 800 F, 0.1 to 3 LHSV, and 200 to 3000 psig. Catalysts useful for the hydrofinishing reaction are preferably combinations of nickel, cobalt and molybdenum supported on zeolites or amorphous material. 
     Alternate embodiments, not pictured, include a series of reactors in which one or more of the reactors contains internal separation means, rather than an external separator or flash drum following the reactor. In another embodiment, there is no interstage separation between one or more of the reactors in series. 
     The process for the preparation of the catalyst slurry composition used in this invention is set forth in U.S. Ser. No. 10/938,003 and U.S. Ser. No. 10/938,202 and is incorporated by reference. In one embodiment, the slurry catalyst composition is formed from the combination of a slurry comprising Group VIB and Group VIII metals and a hydrocarbon oil having a viscosity of at least 2 cSt (or 32.8 SSU) @212° F., forming an active catalyst composition admixed with the hydrocarbon oil. The preferred viscosity range for the hydrocarbon oil is from at least about 2 cSt (or 32.8 SSU) @212° F. to 15 cSt (or 77.9 SSU) @212° F. The catalyst composition is useful for upgrading carbonaceous feedstocks which include atmospheric gas oils, vacuum gas oils, deasphalted oils, olefins, oils derived from tar sands or bitumen, oils derived from coal, heavy crude oils, synthetic oils from Fischer-Tropsch processes, and oils derived from recycled oil wastes and polymers. The catalyst composition is useful for but not limited to hydrogenation upgrading processes such as thermal hydrocracking, hydrotreating, hydrodesulfurization, hydrodenitrogenation, and hydrodemetalization. 
     The feeds suitable for use in this invention are set forth in U.S. Ser. No. 10/938,269 and include atmospheric residuum, vacuum residuum,tar from a solvent deasphalting unit, atmospheric gas oils, vacuum gas oils, deasphalted oils, olefins, oils derived from tar sands or bitumen, oils derived from coal, heavy crude oils, synthetic oils from Fischer-Tropsch processes, and oils derived from recycled oil wastes and polymers. Suitable feeds also include atmospheric residuum, vacuum residuum and tar from a solvent deasphlating unit. 
     The preferred type of reactor in the instant invention is a liquid recirculating reactor, although other types of upflow reactors may be employed. Liquid recirculating reactors are discussed further in copending application Ser. No. 11/305,359 or US Patent Publication No. US2007140927 (T6493) which is incorporated by reference. 
     A liquid recirculation reactor is an upflow reactor to which is fed heavy hydrocarbon oil admixed with slurry catalyst and a hydrogen rich gas at elevated pressure and temperature, for hydroconversion. 
     Hydroconversion includes processes such as hydrocracking and the removal of heteroatom contaminants (such sulfur and nitrogen). In slurry catalyst use, catalyst particles are extremely small (1-10 micron). Pumps are not generally needed for recirculation, although they may be used. Sufficient motion of the catalyst is usually established without them. 
     EXAMPLE 
     In-line Hydrofinishing Performance 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                   
                 Feed from 
                   
                   
                   
               
               
                   
                 slurry 
                 Full Range 
                 Jet Fuel Cut 
               
               
                   
                 hydrocracker 
                 Product from 
                 from 
                 Diesel Cut 
               
               
                   
                 to 
                 Hydro- 
                 Hydro- 
                 from 
               
               
                   
                 Hydrofinisher 
                 finisher 
                 finisher 
                 Hydrofinisher 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 API 
                 34.8 
                 38.9 
                   
                   
               
               
                 Sulfur, 
                 3300 
                 6 
                 &lt;2 
                 3 
               
               
                 wppm 
               
               
                 Nitrogen, 
                 2500 
                 23 
                 6 
                 8 
               
               
                 wppm 
               
               
                 Smoke 
                   
                   
                 19 
               
               
                 Point, 
               
               
                 mm 
               
               
                 Cetane 
                   
                   
                   
                 44 
               
               
                 Index 
               
               
                   
               
            
           
         
       
     
     It is apparent from the Table above that hydrofinishing of the product of slurry hydrocracking provides dramatic reduction of sulfur and nitrogen content. In both full range product and in individual product cuts, such as jet fuel and diesel.