Process for the conversion of heavy charge stocks such as heavy crude oils and distillation residues

Abstract

Process for the conversion of heavy charge stocks selected from heavy and extra-heavy crude oils, distillation residues, heavy oils from catalytic treatment, thermal tars, bitumens from oil sands, carbons of different origins and other high boiling charges of a hydrocarbon origin known as “black oils”, by means of the combined used of at least the three following process units: solvent deasphalting (SDA), hydroconversion with slurry phase catalysts (HT), distillation or flash (D), characterized in that it comprises the following steps: sending the heavy charge stock to a deasphalting section (SDA) in the presence of solvents, obtaining two streams, one consisting of deasphalted oil (DAO), the other containing asphaltenes; mixing the stream consisting of deasphalted oil (DAO) with a suitable hydrogenation catalyst precursor and sending the mix obtained to a hydrotreating reactor (HT), introducing, into the same reactor, hydrogen or a mix containing hydrogen and H 2 S; sending the stream containing the product of the hydrotreatment reaction and the catalyst in dispersed phase to one or more distillation or flash (D) steps, by means of which the most volatile fractions are separated, among which the gases produced in the hydrotreatment reaction, from the distillation residue (tar) or from the liquid coming from the flash unit; recycling of at least a portion of the distillation residue (tar) or the liquid coming from the flash unit, containing catalyst in dispersed phase, rich in metal sulphides produced by de-metallization of the charge and possibly coke, to the hydrotreating section (HT).

1 . A process for the conversion of heavy charge stocks selected from heavy and extra-heavy crude oils, distillation residues, heavy oils from catalytic treatment, thermal tars, bitumens from oil sands, carbons of different origins and other high boiling charges of a hydrocarbon origin known as “black oils”, by the combined used of at least the three following process units: solvent deasphalting (SDA), hydroconversion with slurry phase catalysts (HT), distillation or flash (D),  
     characterized in that it comprises the following steps: 
 sending the heavy charge stock to a deasphalting section (SDA) in the presence of solvents, obtaining two streams, one consisting of deasphalted oil (DAO), the other containing asphaltenes;  
 mixing the stream consisting of deasphalted oil (DAO) with a suitable hydrogenation catalyst precursor and sending the mix obtained to a hydrotreatment reactor (HT), introducing into the same reactor, hydrogen or a mix containing hydrogen and H 2 S;  
 sending the stream containing the product of the hydrotreatment reaction and the catalyst in dispersed phase to one or more distillation or flash (D) steps, whereby the most volatile fractions are separated, among which the gases produced in the hydrotreatment reaction, from the distillation residue (tar) or from the liquid coming from the flash unit;  
 recycling of at least a portion of the distillation residue (tar) or of the liquid coming from the flash unit, containing catalyst in dispersed phase, rich in metal sulphides produced by de-metallization of the charge and possibly coke, to the hydrotreatment section (HT).  
 
   
   
       2 . The process according to  claim 1 , wherein the stream containing asphaltenes obtained in the de-asphalting section (SDA) is mixed with the remaining part of the distillation residue (tar) or the liquid coming from the flash unit which was not recycled to the hydrotreatment section (HT).  
   
   
       3 . The process according to  claim 1  or  2 , wherein the stream containing asphaltenes obtained in the de-asphalting section (SDA) is sent to a gasification section (PO x ) in order to obtain a mix of H 2  and CO.  
   
   
       4 . The process according to  claim 1  or  2 , wherein the stream containing asphaltenes obtained in the deasphalting section (SDA) is sent to a coking or visbreaking section  
   
   
       5 . The process according to  claim 1  or  2 , wherein the stream containing asphaltenes obtained in the de-asphalting section (SDA) is used for the formulation of fuels or as fuel for power production or is used in cement works.  
   
   
       6 . The process according to  claim 3 , wherein the gasification is effected by feeding to the gasification unit, in addition to the charge stock, oxygen and vapour which react under exothermic conditions at a temperature of over 1300° C. and a pressure ranging from 30 to 80 bar, to produce mainly H 2  and CO.  
   
   
       7 . The process according to  claim 1 , wherein at least 80% by weight of the distillation residue (tar) or the liquid coming from the flash unit is recycled to the hydrotreatment section (HT).  
   
   
       8 . The process according to  claim 7 , wherein at least 90% by weight of the distillation residue or the liquid coming from the flash unit is recycled to the hydrotreatment section (HT).  
   
   
       9 . The process according to  claim 8 , wherein at least 99% by weight of the distillation residue or the liquid coming from the flash unit is recycled to the hydrotreatment section (HT).  
   
   
       10 . The process according to  claim 3 , wherein part of the hydrogen obtained from the gasification section (PO x ) is sent to the hydrotreatment (HT) step.  
   
   
       11 . The process according to  claim 1 , wherein the distillation steps are carried out at reduced pressure, ranging from 0.001 to 0.5 MPa.  
   
   
       12 . The process according to  claim 11 , wherein the distillation steps are carried out at reduced pressure, ranging from 0.01 to 0.3 MPa.  
   
   
       13 . The process according to  claim 1 , wherein the hydrotreatment (HT) step is carried out at a temperature ranging from 360 to 450° C. and at a pressure ranging from 3 to 30 MPa.  
   
   
       14 . The process according to  claim 13 , wherein the hydrotreatment (HT) step is carried out at a temperature ranging from 380 to 440° C. and at a pressure ranging from 10 to 20 MPa.  
   
   
       15 . The process according to  claim 1 , wherein the deasphalting (SDA) step is carried out at temperatures ranging from 40 to 200° C. and a pressure ranging from 0.1 to 7 MPa.  
   
   
       16 . The process according to  claim 1 , wherein the solvent of the deasphalting step (SDA) is a light paraffin with a number of carbon atoms ranging from 3 to 6.  
   
   
       17 . The process according to  claim 16 , wherein the deasphalting solvent is a light paraffin with a number of carbon atoms ranging from 4 to 5.  
   
   
       18 . The process according to  claim 1 , wherein the deasphalting (SDA) step is effected with recovery of the solvent in supercritical phase.  
   
   
       19 . The process according to  claim 1 , wherein, before being sent to one or more distillation or flash steps, the stream containing the hydrotreatment reaction product and the catalyst in dispersed phase, is sent to a separation pre-step carried out at high pressure so as to obtain a light fraction and a heavy fraction, said heavy fraction alone being sent to said distillation (D) step(s).  
   
   
       20 . The process according to  claim 19 , wherein the light fraction obtained by means of the high pressure separation step, is sent to a secondary post-treatment hydrogenation step, thus producing a lighter fraction containing C 1 -C 4  gas and H 2 S and a heavier fraction containing hydrotreated naphtha and gas oil.  
   
   
       21 . The process according to  claim 20 , wherein the post-treatment hydrogenation reaction is effected at a pressure ranging from 7 to 14 MPa.  
   
   
       22 . The process according to  claim 1 , wherein the hydrogenation catalyst is an easily decomposable precursor or a preformed compound based on one or more transition metals.  
   
   
       23 . The process according to  claim 22 , wherein the transition metal is molybdenum.  
   
   
       24 . The process according to  claim 1 , wherein the catalyst concentration in the hydroconversion reactor, defined on the basis of the concentration of the metal(s) present, ranges from 350 to 30,000 ppm.  
   
   
       25 . The process according to  claim 24 , wherein the catalyst concentration in the hydroconversion reactor ranges from 3,000 to 20,000 ppm.  
   
   
       26 . The process according to  claim 25 , wherein the catalyst concentration in the hydroconversion reactor ranges from 5,000 to 15,000 ppm.