Radiant tube assembly

Abstract

The present concept is a radiant tube assembly that includes a burner assembly firing combustion gases into a combustion tube which emits radiant heat energy from its outer surface. A black ceramic coating is applied the outer surface of the combustion tube to increase the emissivity of the combustion tube and lower the temperature of the outer surface of the combustion tube. Semi-circular top and semi-circular bottom inserts extending longitudinally along the length of a first section of the combustion tube lower the combustion tube outer temperature.

I claim: 
     
         1 . A radiant tube assembly comprising:
 a) a burner assembly firing combustion gases into a combustion tube wherein, the combustion gases travelling down the interior of the combustion tube;   b) the combustion tube emits radiant heat energy from an outer surface of the combustion tube;   c) a black ceramic coating applied to an outer surface extending from a start point and along the combustion tube for increasing the emissivity of the combustion tube thereby lowering the temperature of the outer surface of the combustion tube.   
     
     
         2 . The radiant tube assembly claimed in  claim 1  wherein the black ceramic coating is applied to the outer surface of the first 4 to 12 feet of the combustion tube 
     
     
         3 . The radiant tube assembly claimed in  claim 2  wherein the black ceramic coating is applied to the outer surface providing an emissivity greater than 0.88. 
     
     
         4 . The radiant tube assembly claimed in  claim 2  wherein the black ceramic coating is applied to the outer surface providing an emissivity greater than 0.90. 
     
     
         5 . The radiant tube assembly claimed in  claim 3  wherein the combustion tube includes a single top insert extending from a start point and into the combustion tube, and wherein the top insert lies adjacent to the inner surface of the combustion tube and is semi-circular in cross section wherein the insert lowers the tube outer surface temperature. 
     
     
         6 . The radiant tube assembly claimed in  claim 3  wherein at least the first 4 feet of the combustion tube includes a single top insert which lies adjacent to the inner surface of the combustion tube wherein the top insert is semi-circular in cross section wherein the insert lowers the tube outer surface temperature. 
     
     
         7 . The radiant tube assembly claimed in  claim 3  wherein at least the first 4 feet of the combustion tube includes a single top insert which lies adjacent to the inner surface of the combustion tube wherein the single top insert is over semi-circular in cross section such that it is self-supporting within the combustion tube wherein the insert lowers the tube outer surface temperature. 
     
     
         8 . The radiant tube assembly claimed in  claim 3  wherein the combustion tube includes a single top insert extending from a start point and into the combustion tube, which lies adjacent to the inner surface of the combustion tube and a single bottom insert extending from a start point and into the combustion tube, which lies adjacent to the inner surface of the combustion tube, wherein the top and bottom inserts are semi-circular in cross section and abut along a longitudinal joint wherein the inserts lower the tube outer surface temperature. 
     
     
         9 . The radiant tube assembly claimed in  claim 8  wherein at least the first 4 feet of the combustion tube includes a single top insert and a single bottom insert. 
     
     
         10 . The radiant tube assembly claimed in  claim 3  wherein the combustion tube includes a top insert extending from a start point and into the combustion tube, which lies adjacent to the inner surface of the combustion tube and a bottom insert extending from a start point and into the combustion tube, which lies adjacent to the inner surface of the combustion tube, wherein the top and bottom inserts are semi-circular in cross section and abut along a longitudinal joint and further includes an additional single top insert which abuts the other inserts at a transverse joint wherein the inserts lower the tube outer surface temperature. 
     
     
         11 . The radiant tube assembly claimed in  claim 10  wherein the single top insert is semi-circular in cross section. 
     
     
         12 . The radiant tube assembly claimed in  claim 10  wherein the single top insert is over semi-circular in cross section such that it is self-supporting within the combustion tube. 
     
     
         13 . The radiant tube assembly claimed in  claim 10  wherein at least the first 4 feet of the combustion tube includes the top and bottom inserts. 
     
     
         14 . The radiant tube assembly claimed in  claim 10  wherein at least the first 4 feet of the combustion tube includes the top and bottom inserts and the single top insert is also at least 4 feet in length. 
     
     
         15 . A radiant tube assembly comprising:
 a) a burner assembly firing combustion gases into a combustion tube wherein, the combustion gases travelling down the interior of the combustion tube;   b) the combustion tube emits radiant heat energy from an outer surface of the combustion tube;   c) a black ceramic coating applied to an outer surface extending from a start point and along the combustion tube for increasing the emissivity of the combustion tube thereby lowering the temperature of the outer surface of the combustion tube;   d) a semi-circular top insert and a semi-circular bottom insert extending longitudinally along the length of a first section of the combustion tube, the inserts for lowering the combustion tube outer temperature.   
     
     
         16 . The radiant tube assembly claimed in  claim 15  wherein inserts extend along the length of the first two sections of the combustion tube. 
     
     
         17 . The radiant tube assembly claimed in  claim 15  wherein the first section extends from a start point to 3 to 6 feet along the length of the combustion tube. 
     
     
         18 . The radiant tube assembly claimed in  claim 16  wherein the second section extends from 6 to 12 feet along the length of the combustion tube.