Methods and systems for producing light olefins from naphtha

Abstract

Methods and systems for producing olefins from a naphtha feedstock are provided. Methods can include pyrolyzing the naphtha feedstock in the presence of hydrogen gas to produce a first effluent, separating the first effluent into light components, heavy components and one or more olefin product streams, steam cracking the light components to produce a second effluent, and extracting aromatics, if any, from the heavy components to produce a third effluent.

1 . A method for producing olefins and aromatics from a naphtha feedstock, the method comprising the steps of:
 (a) pyrolyzing the naphtha feedstock in the presence of hydrogen gas to produce a first effluent comprising first olefins;   (b) separating the first effluent into light components, heavy components, if any, and one or more olefin product streams;   (c) steam cracking the light components to produce a second effluent comprising second olefins; and   (d) extracting aromatics, if any, from the heavy components to produce a third effluent.   
     
     
         2 . The method of  claim 1 , wherein the first effluent comprises C 2  to C 4  paraffins and iso-paraffins. 
     
     
         3 . The method of  claim 1 , wherein after pyrolyzing, the first effluent has a temperature of about 700° C. to about 860° C. 
     
     
         4 . The method of  claim 1 , wherein after steam cracking, the second effluent has a temperature of about 820° C. to about 880° C. 
     
     
         5 . The method of  claim 1 , wherein the separating the first effluent comprises compressing the first effluent to pressurize the first effluent and condense the heavy components. 
     
     
         6 . The method of  claim 5 , further comprising treating the first effluent to remove carbon dioxide and water, if any. 
     
     
         7 . The method of  claim 1 , further comprising combining the first effluent and the second effluent prior to the separating. 
     
     
         8 . The method of  claim 1 , further comprising the steps of:
 (e) extracting hydrogen, if any, from the light components to produce a hydrocarbon stream and recycling the hydrogen by mixing it with the naphtha feedstock;   (f) extracting methane, if any, from the hydrocarbon stream to produce a C 2 + stream;   (g) extracting ethylene and ethane, if any, from the C 2 + stream to produce a C 3 + stream;   (h) extracting propylene and propane, if any, from the C 3 + stream to produce a C 4 + stream;   (i) extracting C 4  components, if any, from the C 4 + stream to produce a C 5 + stream; and   (j) extracting benzene, toluene, xylene, ethylbenzene, C 9 + aromatics and heavy oil, if any, from the heavy components and the C 5 + stream to produce a third effluent.   
     
     
         9 . The method of  claim 8 , further comprising recycling the third effluent by combining it with the naphtha feedstock. 
     
     
         10 . The method of  claim 8 , further comprising pyrolyzing the third effluent. 
     
     
         11 . The method of any  claim 8 , further comprising purifying the hydrogen by removing carbon monoxide and methane, if any. 
     
     
         12 . The method of  claim 11 , wherein the carbon monoxide is converted to methane and water, wherein the water is removed to produce a hydrogen stream comprising from about 85 vol-% to about 95 vol-% hydrogen. 
     
     
         13 . The method of  claim 12 , wherein the methane is removed by pressure swing adsorption to produce a purified hydrogen stream comprising greater than about 99 vol-% hydrogen. 
     
     
         14 . The method of  claim 8 , further comprising recycling the hydrogen by combining it with the naphtha feedstock. 
     
     
         15 . The method of  claim 8 , further comprising transferring the hydrogen to one or more hydrogenation reactors. 
     
     
         16 . The method of  claim 8 , further comprising the separating the ethylene and ethane into an ethylene product stream and an ethane stream. 
     
     
         17 . The method of  claim 8 , further comprising separating the propylene and propane into a propylene product stream and a propane stream. 
     
     
         18 . The method of  claim 8 , further comprising steam cracking the ethane stream and the propane stream. 
     
     
         19 . The method of  claim 8 , further comprising the steps of:
 (k) extracting C 4  and lighter hydrocarbons, if any, from the heavy components and the C 5 + stream to produce a C 4 − stream; and   (l) recycling the C 4 − stream by combining it with the first effluent and/or the second effluent.   
     
     
         20 . A method for producing olefins and aromatics from a naphtha feedstock, the method consisting of the steps of:
 (a) pyrolyzing the naphtha feedstock in the presence of hydrogen gas to produce a first effluent comprising first olefins;   (b) separating the first effluent into light components and heavy components and an olefin product streams, wherein the heavy components comprise aromatics;   (c) steam cracking the light components to produce a second effluent comprising second olefins; and   (d) extracting aromatics from the heavy components to produce a third effluent, wherein the yield sum of the ethylene and the propylene is greater than about 51%.