Integrated hydrotreating and steam pyrolysis process including hydrogen redistribution for direct processing of a crude oil

Abstract

Steam pyrolysis and hydroprocessing are integrated including hydrogen redistribution to permit direct processing of crude oil feedstocks to produce petrochemicals including olefins and aromatics. A feed is initially split into a light portion and a heavy portion, and the heavy portion is hydroprocessed. A hydroprocessed effluent is charged, along with steam, to a convection section of a steam pyrolysis zone. The mixture is heated and passed to a vapor-liquid separation section. A residual portion is removed and light components are charged to a pyrolysis section of the steam pyrolysis zone. A mixed product stream is recovered from the steam pyrolysis zone and it is separated into product including olefins and aromatics.

1 . An integrated hydrotreating and steam pyrolysis process for the direct processing of a crude oil to produce olefinic and aromatic petrochemicals, the process comprising:
 a. separating the crude oil into light components and heavy components;   b. charging the heavy components and hydrogen to a hydroprocessing zone operating under conditions effective to produce a hydroprocessed effluent having a reduced content of contaminants, an increased paraffinicity, reduced Bureau of Mines Correlation Index, and an increased American Petroleum Institute gravity;   c. charging hydroprocessed effluent and steam to a convection section of a steam pyrolysis zone for heating;   d. charging light components from step (a) and at least a portion of the heated hydroprocessed effluent to a pyrolysis section of the steam pyrolysis zone for thermal cracking;   e. recovering a mixed product stream from the steam pyrolysis zone;   f. separating the thermally cracked mixed product stream;   g. purifying hydrogen recovered in step (h) and recycling it to step (b);   h. recovering olefins and aromatics from the separated mixed product stream; and   i. recovering pyrolysis fuel oil from the separated mixed product stream.   
     
     
         2 . The integrated process of  claim 1 , wherein
 step (f) comprises
 compressing the thermally cracked mixed product stream with plural compression stages; 
 subjecting the compressed thermally cracked mixed product stream to caustic treatment to produce a thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide; 
 compressing the thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide; 
 dehydrating the compressed thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide; 
 recovering hydrogen from the dehydrated compressed thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide; and 
 obtaining olefins and aromatics as in step (j) and pyrolysis fuel oil as in step (k) from the remainder of the dehydrated compressed thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide; 
   
       and
 step (g) comprises purifying recovered hydrogen from the dehydrated compressed thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide for recycle to the hydroprocessing zone. 
 
     
     
         3 . The integrated process of  claim 2 , wherein recovering hydrogen from the dehydrated compressed thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide further comprises separately recovering methane for use as fuel for burners and/or heaters in the thermal cracking step. 
     
     
         4 . The integrated process of  claim 1  wherein the heated hydroprocessed effluent is separated into a light fraction and a heavy fraction in a vapor-liquid separation device based on physical and mechanical separation, wherein the light fraction is charged to the pyrolysis section. 
     
     
         5 . The integrated process of  claim 4  wherein the heavy fraction from the vapor-liquid separation section is blended with pyrolysis fuel oil recovered in step (i). 
     
     
         6 . The integrated process of  claim 1 , wherein the heated hydroprocessed effluent is separated into a light fraction and a heavy fraction in a vapor-liquid separation device which includes
 a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving the flowing fluid mixture and a curvilinear conduit,   a controlled cyclonic section having
 an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section, 
 a riser section at an upper end of the cyclonic member through which vapors pass; 
   and   a liquid collector/settling section through which liquid passes.   
     
     
         7 . The integrated process of  claim 1 , further comprising
 separating the hydroprocessing zone reactor effluents in a high pressure separator to recover a gas portion that is cleaned and recycled to the hydroprocessing zone as an additional source of hydrogen, and liquid portion, and   separating the liquid portion from the high pressure separator in a low pressure separator into a gas portion and a liquid portion, wherein the liquid portion from the low pressure separator is the hydroprocessed effluent subjected to thermal cracking and the gas portion from the low pressure separator is combined with the mixed product stream after the steam pyrolysis zone and before separation in step (f).   
     
     
         8 . The integrated process of  claim 1 , further comprising separating the hydroprocessed effluent into a heavy fraction and a light fraction in a hydroprocessed effluent separation zone, wherein the light fraction is the thermal cracking feed to the pyrolysis section in step (d), and blending the heavy fraction with pyrolysis fuel oil recovered in step (i). 
     
     
         9 . The integrated process of  claim 8 , wherein the hydroprocessed effluent separation zone is a flash separation apparatus. 
     
     
         10 . The integrated process of  claim 8 , wherein the hydroprocessed effluent separation zone is a physical or mechanical apparatus for separation of vapors and liquids. 
     
     
         11 . The integrated process of  claim 8 , wherein the hydroprocessed effluent separation zone comprises a flash vessel having at it inlet a vapor-liquid separation device including
 a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving the flowing fluid mixture and a curvilinear conduit,   a controlled cyclonic section having
 an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section, and 
 a riser section at an upper end of the cyclonic member through which the light fraction passes, 
   wherein a bottom portion of the flash vessel serves as a collection and settling zone for the heavy fraction prior to passage of all or a portion of said heavy fraction.