Systems and methods for steam cracking hydrocarbons

Abstract

Systems and methods for steam cracking a hydrocarbon stream are disclosed. The methods include steam cracking a hydrocarbon stream in a steam cracker that comprises polymer composite tubes in the convection section of the steam cracking furnaces.

What is claimed is: 
     
         1 . A method of processing a hydrocarbon stream, the method comprising: steam-cracking the hydrocarbon stream in a steam cracker comprising a convection section that comprises one or more polymer composite tubes. 
     
     
         2 . A method of processing a pyrolysis oil stream, the method comprising the steps of:
 removing heteroatom contaminants from the pyrolysis oil stream in a purification unit to produce a purified pyrolysis oil; and   steam-cracking the purified pyrolysis oil stream in a steam cracker to produce olefins and aromatics, wherein the steam cracker comprises a convection section that includes one or more polymer composite tubes.   
     
     
         3 . The method of  claim 2 , wherein the convection section includes a feed preheater of the steam cracker. 
     
     
         4 . The method of  claim 3 , wherein the feed pre-heater is operated at a temperature of 140 to 260° C. 
     
     
         5 . The method of  claim 3 , wherein the feed pre-heater is heated by a flue gas generated in a radiant section of the steam cracker. 
     
     
         6 . The method of  claim 2 , wherein the polymer composite tubes comprise polyphenylene sulphide (PPS), polyvinylidene difluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene (PE), polycarbonate (PC), polyphenylene oxide (PPO), perfluoroalcoxy (PFA), or combinations thereof. 
     
     
         7 . The method of  claim 2 , wherein the polymer composite tubes have an operating temperature limit of 20 to 300° C. 
     
     
         8 . The method of  claim 2 , wherein the purifying unit comprises an adsorption unit, a hydrotreatment unit. 
     
     
         9 . The method of  claim 2 , wherein the pyrolysis oil comprises more than 10 wt. % unsaturated molecules. 
     
     
         10 . The method of  claim 2 , wherein the polymer composite tubes are configured to mitigate fouling of unsaturated molecules in the steam cracker. 
     
     
         11 . The method of  claim 2 , wherein the convection section of the steam cracker comprises a feed pre-heater bank, an upper mixed pre-heater bank, and a lower mixed pre-heater bank. 
     
     
         12 . A method of processing a pyrolysis oil stream, the method comprising:
 removing heteroatom contaminants from the pyrolysis oil stream in a purification unit to produce a purified pyrolysis oil; and   steam-cracking the purified pyrolysis oil stream in a steam cracker to produce olefins and aromatics, wherein the steam cracker comprises a feed preheater that comprises one or more polymer composite tubes.