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

Abstract

An integrated hydrotreating and steam pyrolysis process for the direct processing of a crude oil is provided to produce olefinic and aromatic petrochemicals. Crude oil and hydrogen are charged to a hydroprocessing zone operating under conditions effective to produce a hydroprocessed effluent reduced having a reduced content of contaminants, an increased paraffinicity, reduced Bureau of Mines Correlation Index, and an increased American Petroleum Institute gravity. Hydroprocessed effluent is thermally cracked in the presence of steam to produce a mixed product stream, which is separated. Hydrogen from the mixed product stream is purified and recycled to the hydroprocessing zone, and olefins and aromatics are recovered from the separated mixed product stream.

1 . An integrated hydrotreating and steam pyrolysis process for the direct processing of crude oil to produce olefinic and aromatic petrochemicals, the process comprising:
 a. charging the crude oil 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;   b. thermally cracking hydroprocessed effluent in the presence of steam in a steam pyrolysis zone to produce a mixed product stream;   c. separating the thermally cracked mixed product stream into hydrogen, olefins, aromatics and pyrolysis fuel oil;   d. purifying hydrogen recovered in step (c) and recycling it to step (a);   e. recovering olefins and aromatics from the separated mixed product stream; and   f. recovering pyrolysis fuel oil from the separated mixed product stream.   
     
     
         2 . The integrated process of  claim 1 , further comprising separating the hydroprocessed effluent from the hydroprocessing zone into a heavy fraction and a light fraction in a hydroprocessed effluent separation zone, wherein the light fraction is the hydroprocessed effluent that is thermally cracked in step (b), and blending the heavy fraction with pyrolysis fuel oil recovered in step (f). 
     
     
         3 . The integrated process of  claim 2 , wherein the hydroprocessed effluent separation zone is a flash separation apparatus. 
     
     
         4 . The integrated process of  claim 2 , wherein the hydroprocessed effluent separation zone is a physical or mechanical apparatus for separation of vapors and liquids. 
     
     
         5 . The integrated process of  claim 1 , wherein
 step (c) 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 (e) and pyrolysis fuel oil as in step (f) from the remainder of the dehydrated compressed thermally cracked mixed product stream with a reduced content of hydrogen sulfide and carbon dioxide; 
   
       and
 step (d) 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. 
 
     
     
         6 . The integrated process of  claim 5 , 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. 
     
     
         7 . The integrated process of  claim 1  wherein the thermal cracking step comprises heating hydroprocessed effluent in a convection section of a steam pyrolysis zone, separating the heated hydroprocessed effluent into a vapor fraction and a liquid fraction, passing the vapor fraction to a pyrolysis section of a steam pyrolysis zone, and discharging the liquid fraction. 
     
     
         8 . The integrated process of  claim 7  wherein the discharged liquid fraction is blended with pyrolysis fuel oil recovered in step (f). 
     
     
         9 . The integrated process of  claim 6  wherein separating the heated hydroprocessed effluent into a vapor fraction and a liquid fraction is with a vapor-liquid separation device based on physical and mechanical separation. 
     
     
         10 . The integrated process of  claim 9  wherein the vapor-liquid separation device 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. 
 
     
     
         11 . 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 (c).   
     
     
         12 . The integrated process of  claim 2 , 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,   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 separation into a light fraction and a heavy fraction, 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 (c).