Hydrocracking process and system including removal of heavy poly nuclear aromatics from hydrocracker bottoms by coking

Abstract

Hydrocracker bottoms fractions are treated to remove HPNA compounds and/or HPNA precursor compounds and produce a reduced-HPNA stream effective for recycle, in a configuration of a single-stage hydrocracking reactor, series-flow once through hydrocracking operation, or two-stage hydrocracking operation. The hydrocracker bottoms fractions are subjected to thermal cracking and HPNA compounds are removed with the coke phase.

1 . A process for separation of heavy poly nuclear aromatic (HPNA) compounds and/or HPNA precursor compounds from a hydrocracker bottoms fraction prior to recycling within a hydrocracking operation, the process comprising:
 subjecting the hydrocracker bottoms fraction to thermal cracking in a coking zone to produce thermally cracked hydrocarbon products and coke, wherein the coke contains HPNA compounds and/or HPNA precursor compounds from the hydrocracker bottoms fraction; and   recycling all or a portion of the thermally cracked hydrocarbon products within the hydrocracking operation.   
     
     
         2 . A hydrocracking process comprising:
 subjecting a hydrocarbon stream to one or more hydrocracking stages to produce a hydrocracked effluent;   fractionating the hydrocracked effluent to recover one or more hydrocracked product fractions and a hydrocracker bottoms fraction corresponding to the hydrocracked bottoms fraction of  claim 1 ;   wherein recycling all or a portion of the thermally cracked hydrocarbon products within the hydrocracking operation comprises recycling all or a portion of the thermally cracked hydrocarbon products to at least one of the one or more hydrocracking stages.   
     
     
         3 . A two stage hydrocracking process comprising:
 subjecting the hydrocarbon stream to a first hydrocracking stage to produce a first hydrocracked effluent;   fractionating the first hydrocracked effluent to recover one or more hydrocracked product fractions and a hydrocracker bottoms fraction corresponding to the hydrocracked bottoms fraction of  claim 1 ;   wherein recycling all or a portion of the thermally cracked hydrocarbon products within the hydrocracking operation comprises passing all or a portion of the thermally cracked hydrocarbon products to at least one of the one or more hydrocracking stages.   
     
     
         4 . The process as in  claim 3 , wherein the second hydrocracked effluent is fractionated with the first hydrocracked effluent. 
     
     
         5 . The process as in  claim 1 , wherein the coking zone produces a coker liquid and gas stream that is fractioned into one or more streams forming recycled thermally cracked hydrocarbon products. 
     
     
         6 . The process as in  claim 5 , wherein the recycled thermally cracked hydrocarbon products are selected from the group consisting of:
 coker gas oil;   coker gas oil and coker middle distillates; and   coker gas oil, coker middle distillates and coker naphtha.   
     
     
         7 - 8 . (canceled) 
     
     
         9 . The process as in  claim 1 , wherein the coking zone is a delayed coker operating at a temperature (° C.) in a coking drum of the delayed coker of about 425-650; a pressure (bars) in the coking drum of about 1-20; and a steam introduction rate of about 0.1-3 wt % relative to the heated residue. 
     
     
         10 . (canceled) 
     
     
         11 . The process as in  claim 1 , wherein the coking zone is a fluid coker operating a temperature (° C.) in a coking drums of the fluid coker of about 450-760; a pressure (bars) in the coking drum of about 1-20; and a steam introduction rate of about 0.1-3 wt % relative to the heated residue. 
     
     
         12 . (canceled) 
     
     
         13 . The process as in  claim 1 , wherein adsorbent material or catalytic material is added to the coking zone. 
     
     
         14 . The process as in  claim 13 , wherein catalytic material is added, and wherein catalytic material is a heterogeneous catalyst selected from the group consisting of silica, alumina, silica-alumina, titania-silica, molecular sieves, silica gel, activated carbon, activated alumina, silica-alumina gel, zinc oxide, clays, fresh catalyst materials, used catalyst materials, regenerated catalyst materials and combinations thereof. 
     
     
         15 . The process as in  claim 14 , wherein the heterogeneous catalyst incudes one or more active metal components of metals or metal compounds selected from the Periodic Table of the Elements IUPAC Groups 4, 5, 6, 7, 8, 9 and 10. 
     
     
         16 . The process as in  claim 15 , wherein the active metal component is a metal or metal compound selected from the group consisting of Mo, V, W, Cr, Fe and combinations thereof. 
     
     
         17 . The process as in  claim 16  wherein the active metal component is a metal or metal compound selected from the group consisting of vanadium pentoxide, molybdenum alicyclic and aliphatic carboxylic acids, molybdenum naphthenate, nickel 2-ethylhexanoate, iron pentacarbonyl, molybdenum 2-ethyl hexanoate, molybdenum di-thiocarboxylate, nickel naphthenate, iron naphthenate and combinations thereof. 
     
     
         18 . The process as in  claim 13 , wherein catalytic material is added, and wherein catalytic material is a homogeneous catalyst that is oil-soluble and contains one or more active metal components of metals or metal compounds selected from the Periodic Table of the Elements IUPAC Groups 4, 5, 6, 7, 8, 9 and 10. 
     
     
         19 . The process as in  18  wherein the homogeneous catalyst is, or contains as an active metal component, a transition metal-based compound derived from an organic acid salt or an organo-metal compound containing Mo, V, W, Cr, Fe and combinations thereof. 
     
     
         20 . The process as in  18  wherein the homogeneous catalyst is, or contains as an active metal compound, a compounds selected from the group consisting of vanadium pentoxide, molybdenum alicyclic and aliphatic carboxylic acids, molybdenum naphthenate, nickel 2-ethylhexanoate, iron pentacarbonyl, molybdenum 2-ethyl hexanoate, molybdenum di-thiocarboxylate, nickel naphthenate, iron naphthenate and combinations thereof. 
     
     
         21 . The process as in  claim 13 , wherein adsorbent material is added, and wherein adsorbent material is selected from the group consisting of silica, alumina, silica-alumina, titania-silica, molecular sieves, silica gel, activated carbon, activated alumina, silica-alumina gel, zinc oxide, clays, fresh catalyst materials, spent catalyst materials, regenerated catalyst materials, and combinations thereof. 
     
     
         22 . The process as in  claim 1 , further comprising introducing additional feed to the coking zone. 
     
     
         23 . The process as in  claim 22 , wherein the additional feed is selected from the group consisting of atmospheric residue, vacuum residue, deasphalted oil and demetallized oil. 
     
     
         24 . The process as in  claim 22 , wherein the additional feed comprises 10-99 wt % of total feed to the coking zone. 
     
     
         25 . (canceled) 
     
     
         26 . The process as in  claim 22 , further comprising subjecting the additional feedstock to residue hydrocracking prior to introducing to the coking zone. 
     
     
         27 . The process as in  claim 22 , further comprising subjecting the additional feedstock to solvent deasphalting prior to introducing to the coking zone. 
     
     
         28 . (canceled) 
     
     
         29 . The process as in  claim 22 , further comprising subjecting the additional feedstock to oxidation prior to introducing to the coking zone. 
     
     
         30 . The process as in  claim 22 , further comprising contacting the additional feedstock with adsorbent material prior to introducing to the coking zone. 
     
     
         31 . A system for removal of heavy poly nuclear aromatic (HPNA) compounds and/or HPNA precursor compounds from a hydrocracker bottoms fraction comprising:
 a coking reaction and separation zone having one or more inlets in fluid communication with a hydrocracker bottoms outlet of a hydrocracking fractionating zone, and one or more outlets for discharging thermally cracked hydrocarbon products in fluid communication with a hydrocracking operation as a bottoms recycle stream, and one or more outlets for coke containing HPNA compounds and/or HPNA precursor compounds from the hydrocracker bottoms fraction.   
     
     
         32 - 34 . (canceled)