Radiant tube in cracking furnaces

Abstract

Radiant tube in a cracking furnace is disclosed. Hydrocarbons are cracked into ethylene in the tube through which hydrocarbons flow, which tube is heated from the outside to a temperature where cracking occurs. The tube is made from a FeCrAl material containing, in addition to Fe, 10 to 25% by weight of Cr, 1 to 10% by weight of Al and 1.5 to 5% by weight of Mo. Optionally, the material comprises up to a total of 2.2 wt. %, preferably up to 2.0 wt. % and more preferably up to 1.0 wt. %, of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.

1 . A radiant tube in a furnace for cracking hydrocarbons, the radiant tube formed of a material comprising: 
 10 to 25 wt. % Cr;    1 to 10 wt. % Al;    1.5 to 5 wt. % Mo; and    balance Fe.    
     
     
         2 . The radiant tube of  claim 1 , wherein the material comprises up to a total of 2.2 wt. % of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.  
     
     
         3 . The radiant tube of  claim 2 , wherein the material comprises up to a total of 2.0 wt. % of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.  
     
     
         4 . The radiant tube of  claim 3 , wherein the material comprises up to a total of 1.0 wt. % of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.  
     
     
         5 . The radiant tube of  claim 1 , wherein the material comprises 2 to 3.5 wt. % of molybdenum.  
     
     
         6 . The radiant tube of  claim 1 , wherein the material has a creep strength sufficiently high to produce a time to break of the tube in excess of 100,000 hours at a temperature of 1100° C. and a load of 2.2 MPa.