The Feasible Research On Sub-reheater Of 670t/h Boiler By Double Sides Heat Transfer Enhancement Technology

There are 180 boilers with the capacity of 670 tons per hour produced by Dongfang Boiler Mill in China, However, the problem of the reheater in this type of boiler are abrasion and leaking by detonation in the tube, and the lower temperature of stream in general. The temperature of the tube went up and then the expenditure of expensive alloy increased by using extern spiral finned tube, which enhanced the external heat transfer. This text came up with a new designation at the first time, which used the three-dimension internal finned tube and the wave-like longitudinal internal finned tube to enhance the both internal and external heat transfer at the lower temperature side-the larger heat transfer coefficient side based on the using the extern spiral finned tube to enhance higher temperature side at the same time. The heat transfer resistances, heat transfer areas of the heat-exchanger, the temperatures of the tube and the changes of flowing resistance in every style of tubes could be calculated by analyses. By the both sides heat transfer enhanced designation with extern spiral finned tube and three-dimension internal finned tube, the results showed that the temperature of tube wall decreased about 35℃ , the quanlity of heat transfer at the equally area increased over 15%,and the use of expansive hot endurable alloy-12CrlMoV was largely decreased compared to designation only using the extern spiral finned tube, and also the loss of stream pressure beyond 30%. All of them could provide proofs for reforming the sub-reheater in boiler.