Reduction of fouling in thermal processing of olefinic feedstocks

Abstract

Reduction of fouling in a thermal process for treating feed streams comprising naphtha, pyrolysis oils or a mixture thereof said feed stream having a combined olefinic content from 10 to 50 weight % and the balance inert hydrocarbons at a temperature from 100° C. to 300° C. which comprises decreasing the amount of carbon steel in the apparatus contacting said feed stream and increasing the amount of stainless steel.

1 . A process to reduce fouling in a petrochemical thermal process for treating a feed stream comprising naphtha, pyrolysis oils or a mixture thereof said feed stream having a combined olefinic content from 10 to 50 weight % and the balance inert hydrocarbons at a temperature from 100° C. to 300° C. which comprises decreasing the amount of carbon steel in the apparatus contacting said feed stream and increasing the amount of stainless steel having an iron content from 60 to 75 weight %, a chrome content from 15 to 21 weight %, a nickel content from 1 to 15 weight %, a manganese content from 0 to 3 weight %, a molybdenum content from 0 to 3 weight % of and the balance comprising one or more elements selected from the group consisting of Si, Co, Cu, and other trace elements provided no single such element is present in an amount of greater than 1 weight %.  
   
   
       2 . The process according to  claim 1 , wherein the olefinic content of said feed stream comprises styrene monomers which are unsubstituted or substituted by one or more C 1-4  alkyl radicals and C 9-12  bicyclic aromatic ring species which are unsubstituted or substituted by one or more C 1-4  alkyl radicals.  
   
   
       3 . The process according to  claim 2 , wherein said feed stream has a content of styrene monomers which are unsubstituted or substituted by one or more C 1-4  alkyl radicals from 25 to 32 weight %.  
   
   
       4 . The process according to  claim 3 , wherein said feed stock has a content of C 9-12  bicyclic aromatic ring species which are unsubstituted or substituted by one or more C 1-4  alkyl radicals from 4 to 10 weight %.  
   
   
       5 . The process according to  claim 4 , wherein said feed stream has a combined content of styrene monomers which are unsubstituted or substituted by one or more C 1-4  alkyl radicals and C 9-12  bicyclic aromatic ring species which are unsubstituted or substituted by one or more C 1-4  alkyl radicals from 35 to 42 weight %.  
   
   
       6 . The process according to  claim 5 , wherein said stainless steel has a surface roughness (R a ) of less than 25 μm.  
   
   
       7 . The process according to  claim 6 , wherein the thermal processing is conducted at a temperature from 150° C. to 250° C.  
   
   
       8 . The process according to  claim 7 , wherein said stainless steel has an iron content of less than 73 weight %.  
   
   
       9 . The process according to  claim 8 , wherein said stainless steel has a chrome content from 21 to 16 weight %.  
   
   
       10 . The process according to  claim 9 , wherein said stainless steel has a Ni content from 0.3 to 13 weight %.  
   
   
       11 . The process according to  claim 10 , wherein said stainless steel has a manganese content from 0.5 to 2 weight %.  
   
   
       12 . The process according to  claim 11 , wherein said stainless steel has a molybdenum content from 0.1 to 2.5 weight %.