Integrated mixed plastic pyrolysis with heavy oil product thermal cracking

Abstract

Systems and processes for converting waste plastics and other waste materials to useful end products. The systems integrate a plastics pyrolysis reactor and a liquid phase thermal cracking reactor to advantageously process the waste plastics to form various hydrocarbon products.

1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . A system for converting waste plastics to lighter hydrocarbons, comprising:
 a melt tank configured for melting a feed stream comprising waste plastic to produce a molten plastic;   a pyrolysis reaction zone configured for pyrolyzing the molten plastic to produce a pyrolysis oil reaction product and a liquid pitch product;   a liquid phase thermal cracking heater configured for thermally cracking a heavy pyrolysis oil while maintaining the heavy pyrolysis oil in a liquid phase to form a thermally cracked product;   a separation system for separating the thermally cracked product and the pyrolysis oil reaction product to recover a pyrolysis gas fraction, a light pyrolysis oil fraction, a medium pyrolysis oil fraction, and a heavy pyrolysis oil fraction; and   a feed line for conveying a portion of the heavy pyrolysis oil fraction to the liquid phase thermal cracking heater as the heavy pyrolysis oil.   
     
     
         14 . The system of  claim 13 , comprising a flow line for mixing a second portion of the heavy pyrolysis oil fraction with the molten plastic upstream of the pyrolysis reaction zone. 
     
     
         15 . The system of  claim 13 , wherein the pyrolysis reaction zone comprises a first stage pyrolysis reactor configured to produce a pyrolysis vapor product and a partially converted molten plastic and a second stage pyrolysis reactor configured to produce a pyrolysis oil and the liquid pitch product. 
     
     
         16 . The system of  claim 15 , comprising a flow line for mixing a second portion of the heavy pyrolysis oil fraction with the partially converted molten plastic upstream of the second stage pyrolysis reactor. 
     
     
         17 . The system of  claim 13 , comprising:
 a flow line for mixing the liquid pitch product with the heavy pyrolysis oil to form a mixed heavy cracker feed;   a flow line for recovering a portion of the mixed heavy cracker feed as a heavy oil product stream; and   a flow line for feeding a remaining portion of the mixed heavy cracker feed as the heavy pyrolysis oil fed to the liquid phase thermal cracking heater.   
     
     
         18 . The system of  claim 13 , comprising:
 a flow line for mixing the liquid pitch product with the heavy pyrolysis oil to form a mixed heavy cracker feed;   a separator configured to separate, under vacuum, the mixed heavy cracker feed to recover a vacuum distillate and a thermal tar; and   a flow line for feeding the vacuum distillate as the heavy pyrolysis oil fed to the liquid phase thermal cracking heater.   
     
     
         19 . A system for converting waste plastics to lighter hydrocarbons, comprising:
 a melt tank configured for melting a feed stream comprising waste plastic to produce a molten plastic;   a pyrolysis reaction zone comprising:
 a first stage pyrolysis reactor configured to pyrolyze the molten plastic to produce a pyrolysis vapor product and a partially converted molten plastic; and 
 a second stage pyrolysis reactor configured to pyrolyze the partially converted molten plastic to produce a pyrolysis oil reaction production and a liquid pitch product 
   a liquid phase thermal cracking heater configured for thermally cracking a heavy pyrolysis oil while maintaining the heavy pyrolysis oil in a liquid phase to form a thermally cracked product;
 a separation system for separating the thermally cracked product and the pyrolysis oil reaction product to recover a pyrolysis gas fraction, a light pyrolysis oil fraction, a medium pyrolysis oil fraction, and a heavy pyrolysis oil fraction; and 
 a feed line for conveying a portion of the heavy pyrolysis oil fraction to the liquid phase thermal cracking heater as the heavy pyrolysis oil. 
   
     
     
         20 . The system of  claim 19 , comprising a flow line for mixing a second portion of the heavy pyrolysis oil fraction with the molten plastic upstream of the pyrolysis reaction zone. 
     
     
         21 . The system of  claim 19 , comprising a flow line for mixing a second portion of the heavy pyrolysis oil fraction with the partially converted molten plastic upstream of the second stage pyrolysis reactor. 
     
     
         22 . The system of  claim 19 , comprising:
 a flow line for mixing the liquid pitch product with the heavy pyrolysis oil to form a mixed heavy cracker feed;   a flow line for recovering a portion of the mixed heavy cracker feed as a heavy oil product stream; and   a flow line for feeding a remaining portion of the mixed heavy cracker feed as the heavy pyrolysis oil fed to the liquid phase thermal cracking heater.   
     
     
         23 . The system of  claim 19 , comprising:
 a flow line for mixing the liquid pitch product with the heavy pyrolysis oil to form a mixed heavy cracker feed;   a separator configured to separate, under vacuum, the mixed heavy cracker feed to recover a vacuum distillate and a thermal tar; and   a flow line for feeding the vacuum distillate as the heavy pyrolysis oil fed to the liquid phase thermal cracking heater.   
     
     
         24 . A system for converting waste plastics to lighter hydrocarbons, comprising:
 a melt tank configured for melting a feed stream comprising waste plastic to produce a molten plastic;   a pyrolysis reaction zone configured for pyrolyzing the molten plastic to produce a pyrolysis oil reaction product and a liquid pitch product;   a liquid phase thermal cracking heater configured for thermally cracking a heavy pyrolysis oil while maintaining the heavy pyrolysis oil in a liquid phase to form a thermally cracked product;   a separation system for separating the thermally cracked product and the pyrolysis oil reaction product to recover a pyrolysis gas fraction, a light pyrolysis oil fraction, a medium pyrolysis oil fraction, and a heavy pyrolysis oil fraction;   a feed line for conveying a portion of the heavy pyrolysis oil fraction to the liquid phase thermal cracking heater as the heavy pyrolysis oil;   a flow line for mixing the liquid pitch product with the heavy pyrolysis oil to form a mixed heavy cracker feed;   a separator configured to separate, under vacuum, the mixed heavy cracker feed to recover a vacuum distillate and a thermal tar; and   a flow line for feeding the vacuum distillate as the heavy pyrolysis oil fed to the liquid phase thermal cracking heater.   
     
     
         25 . The system of  claim 24 , comprising a flow line for mixing a second portion of the heavy pyrolysis oil fraction with the molten plastic upstream of the pyrolysis reaction zone. 
     
     
         26 . The system of  claim 24 , wherein the pyrolysis reaction zone comprises a first stage pyrolysis reactor configured to produce a pyrolysis vapor product and a partially converted molten plastic and a second stage pyrolysis reactor configured to produce a pyrolysis oil and the liquid pitch product. 
     
     
         27 . The system of  claim 26 , comprising a flow line for mixing a second portion of the heavy pyrolysis oil fraction with the partially converted molten plastic upstream of the second stage pyrolysis reactor. 
     
     
         28 . The system of  claim 24 , comprising:
 a flow line for mixing the liquid pitch product with the heavy pyrolysis oil to form a mixed heavy cracker feed;   a flow line for recovering a portion of the mixed heavy cracker feed as a heavy oil product stream; and   a flow line for feeding a remaining portion of the mixed heavy cracker feed as the heavy pyrolysis oil fed to the liquid phase thermal cracking heater.