Pressure vessel and method of heating a gas in a pressurised pipe

Abstract

A flowing pressurised gas is heated by being conveyed through a gap ( 18 ) between two concentric tubes ( 16, 17 ) in a pressure vessel ( 11, 12, 13 ). The inner tube ( 17 ) is heated by radiant heat from inside and the tube is kept open towards the flow path of the gas in the pressure vessel so that pressure equalisation is obtained between the inside and outside of the inner tube without the tube being part of the flow path of the gas.

1 . Method of heating a flowing pressurised gas in a pipe to a high temperature by leading the gas through a narrow gap between two tubes fitted in a pressure vessel, wherein the inner of the tubes is heated from the inside and the heated gas is allowed to flow freely from the gap out into the pressure vessel and on to the outlet of the pressure vessel, comprising heating the inner tube from inside by radiant heat from an electric element and keeping the inner tube open towards the flow path of the gas for pressure equalisation between the inside and outside of the tube without the tube forming part of the flow path of the gas. 
     
     
         2 . Method according to  claim 1 , comprising heating a first part of the inner tube seen in the flow direction by a higher power per unit of length than heating a following part of the tube. 
     
     
         3 . Method according to  claim 2 , comprising keeping one end of the inner tube closed and leading the buffer gas in towards the closed end. 
     
     
         4 . Pressure vessel intended to be fitted as part of a pressurised gas pipe and arranged to heat pressurised flowing gas comprising;
 two concentric tubes inside the pressure vessel,   an inlet for pressurised gas into the gap formed between the tubes;   an outlet from the pressure vessel;   wherein the gap between the tubes has its outlet in the pressure vessel and the inner tube has a heating unit for heating the tube from inside; and   wherein the interior of the concentric tubes;
 is open towards the flow path of the gas in the pressure vessel for pressure equalisation between the inside and outside of the inner tube without the tube being part of the flow path of the gas; and 
 has an electric element for heating the tube with radiant heat from inside. 
   
     
     
         5 . Pressure vessel according to  claim 4 , comprising insulation material in the pressure vessel for protecting the pressure vessel walls against high temperature. 
     
     
         6 . Pressure vessel according to  claim 5 , wherein the end of the inner tube towards the outlet in the pressure vessel is closed and the end of the inner tube towards the inlet is open. 
     
     
         7 . Pressure vessel according to  claim 6 , comprising a conduit for buffer gas that leads into the inner tube. 
     
     
         8 . Pressure vessel according to  claim 5 , comprising a passage along the outer of the concentric tubes to hold the inner tube open towards the outlet in the pressure vessel. 
     
     
         9 . Pressure vessel according to  claim 8 , wherein the passage is a gap between the insulation and the outer tube. 
     
     
         10 . The method of  claim 1 , comprising keeping one end of the inner tube closed and leading buffer gas towards the closed end. 
     
     
         11 . Pressure vessel according to  claim 4 , wherein the end of the inner tube towards the outlet in the pressure vessel is closed and the end of the inner tube towards the inlet is open.