Insert Tube and a System of Insert Tubes

Abstract

An insert tube is used for the repair or improvement of a pre-heating tube for air arranged in an exhaust gas pathway of a fuel burner. A pre-determined radial gap exists between the outer surface of the insert tube and the inner surface of the pre-heating tube for air such that the insert tube can be slid into the pre-heating tube for air. The insert tube is provided in the vicinity of each end with at least one groove that runs around its circumference. In the groove there is arranged at least one sealing ring of an elastic material. The sealing ring mounted in the groove has an external diameter that exceeds the internal diameter of the preheating tube for air. The sealing ring forms a seal against the inner surface of the pre-heating tube for air and prevents leakage through the sealing ring.

1 . An insert tube for the repair or the improvement of a pre-heating tube for air arranged at an exhaust gas pathway of a fuel burner, comprising: the pre-heating tube for air being adapted to lead air at a first lower temperature from an inlet channel at one side of the exhaust gas pathway and air that is heated during its passage through the pre-heating tube for air through hot exhaust gases flowing externally to the pre-heating tube for air,
 the heated air being adapted to be led after its passage through the pre-heating tube for air to an outlet channel on the other side of the exhaust gas pathway and onwards to the combustion chamber of the burner in order to be used as combustion air,   a pre-determined radial gap (Δx) existing between the outer surface of the insert tube and the inner surface of the pre-heating tube for air such that the insert tube can be slid into the pre-heating tube for air, either from the inlet channel or from the outlet channel,   the insert tube being provided in the vicinity of each end with at least one groove that runs around its circumference, in which groove there is arranged at least one sealing ring of an elastic material, such that the sealing ring mounted in the groove has an external diameter that exceeds the internal diameter of the pre-heating tube for air, and   the sealing ring forming a seal against the inner surface of the pre-heating tube for air and prevents leakage through the sealing ring, in such a manner that the gap between the insert tube and the pre-heating tube for air forms an insulating layer of air.   
   
   
       2 . The insert tube according to  claim 1 , wherein the sealing ring is constituted by an O-ring. 
   
   
       3 . The insert tube according to  claim 1 , wherein the sealing ring is constituted by a V-ring. 
   
   
       4 . The insert tube according to  claim 1 , wherein the sealing ring is constituted by a piston ring. 
   
   
       5 . The insert tube according to  claim 1 , wherein the sealing ring is constituted by an X-ring. 
   
   
       6 . The insert tube according to  claim 1 , wherein more than one sealing ring ( 102 ) is arranged in each groove. 
   
   
       7 . The insert tube according to  claim 1 , wherein the inlet to the insert tube is in the form of a collar. 
   
   
       8 . The insert tube according to  claim 7 , wherein the collar has the form of a funnel and when in its fully inserted position in the preheating tube for air allows the application of tools behind the collar for the extraction of the insert tube. 
   
   
       9 . The insert tube according to  claim 1 , wherein the insert tube is manufactured from a metallic material. 
   
   
       10 . The insert tube according to  claim 1 , wherein the radial gap (Δx) between the outer surface of the insert tube and the inner surface of the pre-heating tube for air lies in the interval 0.1-3.0 mm. 
   
   
       11 . The insert tube according to  claim 1 , wherein the distance between the sealing rings at the two ends is greater than 20 cm, forming a volume of air in the gap between the insert tube ( 100 ) and the pre-heating tube for air. 
   
   
       12 . A system in a fuel burner comprising:
 several pre-heating tubes for air arranged across an exhaust gas pathway between an inlet channel for cold air and an outlet channel for heated air and where the pre-heating tubes for air is reparable or improved through insert tubes being inserted into each pre-heating tube for air,   several different lengths of insert tube being available for adaptation to cover the region in the pre-heating tube for air   a pre-determined radial gap (Δx) existing between the outer surface of the insert tube and the inner surface of the pre-heating tube for air, such that the insert tube can be slid into the preheating tube for air, either from the inlet channel or from the outlet channel,   the insert tube being provided in the vicinity of each end with at least one groove that runs around its circumference, in which groove there is arranged at least one sealing ring of elastic material, such that the sealing ring mounted in the groove has an external diameter that exceeds the internal diameter of the pre-heating tube for air, and   the sealing ring forming a seal against the inner surface of the preheating tube for air and prevent leakage through the sealing ring ( 102 ), in such a manner that the gap between the insert tube and the pre-heating tube for air forms an insulating layer of air.   
   
   
       13 . The system in a fuel burner according to  claim 12 , wherein the shortest insert tube has a length between 10-30 centimeters, where the subsequent length or lengths are multiples of 2 of this length, whereby the longest insert tube is sufficient to cover the complete preheating tube for air from the inlet channel to the outlet channel.