SLEEVE STRUCTURE OF SLEEVE TYPE GAS PREHEATER

The utility model relates to a casing tube structure of a casing tube type gas preheater. Two or more than two helical fins 3 which are mutually separated are arranged between the inner wall of an outer tube 2 and the outer wall of an inner tube 1, which forms the casing tube structure of a casing tube type gas preheater. The outer tube and the inner tube are sheathed on the same shaft. A planar annular sheet carries out the abscission ring, and then the planar annular sheet is pulled apart, which forms the helical fin 3. The relationship of the pulling length H of the planar annular sheet and the distance L between every two helical fins 3 is as follows: H/L=0.3-2.5. Compared with the casing tube structure of existing continuous helical fins, the heat transfer coefficient is the same, the resistance force is reduced by 35% or so, the manufacture and the fabrication are easy, the cost is lowered by 30% or so, and the installation is convenient.