Thermal cracking vaporization unit construction

Abstract

In the process of employing a liquid whole crude oil and/or natural gas condensate in a thermal cracking process that uses a vaporization/mild cracking unit upstream of a thermal cracking furnace, a martensitic steel is employed in the construction of the unit and the unit is subjected to a de-hydrogenation treatment.

1 . In a method for the processing of at least one of a whole crude oil and a natural gas condensate by a combination of vaporization and mild thermal cracking in a pressure vessel upstream of a thermal cracking furnace, the improvement comprising constructing said pressure vessel from at least one iron based martensitic steel containing minor amounts of chromium, molybdenum, and vanadium. 
     
     
         2 . The method of  claim 1  wherein said steel nominally contains about 9 wt. % chromium, about 1 wt. % molybdenum, and about 0.02 wt. % vanadium. 
     
     
         3 . The method of  claim 1  wherein said steel is grade 91—ASME Section 2A SA387. 
     
     
         4 . In the construction of a vaporization/mild thermal cracking pressure vessel, the improvement comprising constructing said vessel from an iron based martensitic steel containing minor amounts of chromium, molybdenum, and vanadium, employing welding to construct said vessel, and subjecting said vessel to post-welding heat treating. 
     
     
         5 . The method of  claim 4  wherein said steel nominally contains about 9 wt. % chromium, about 1 wt. % molybdenum, and about 0.02 wt. % vanadium. 
     
     
         6 . The method of  claim 4  wherein said vessel in its entirety as constructed is subjected to said post-welding heat treatment. 
     
     
         7 . The method of  claim 6  wherein said de-hydrogenation treatment comprises heating said vessel at a temperature of at least about 600 F for at least about 2 hours.