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运行的电站锅炉中大多数采用蒸汽再热。再热器常由许多并联光管,在单烟道或多烟道中作水平和垂直布置,构成单个的组件。从提高蒸汽循环效率角度来看,再热器需要设计成承受高温(540～575℃),因此再热器布置在高烟温区,如在辐射过热器后或为烟道中的第一级对流受热面(图1)。对设计来说,要求小的蒸汽压降(△ρmax=2～3公斤/厘米~2)和较低的蒸汽压力是限制因素。这些情况就要求设计者选用低的质量流速和大的管径,而结果是管壁向再热蒸汽的放热系数降低。在高热负荷区的再热蒸汽受热面,如出口段的壁温较高。此处采用
The majority of power station boilers operated were steam reheated. Reheaters often consist of many parallel light pipes, arranged horizontally and vertically in a single or multiple stack to form a single unit. From the viewpoint of increasing steam cycle efficiency, the reheater needs to be designed to withstand high temperatures (540-575 ° C) so that the reheater is placed in a high-temperature zone, such as after the superheater is radiated or the first stage convection in the flue Heating surface (Figure 1). For the design, a small vapor pressure drop (Δρmax = 2 to 3 kg / cm 2) and a lower vapor pressure are the limiting factors. These circumstances require the designer to choose a low mass flow rate and a large diameter, and the result is a decrease in the exothermic coefficient of reheat steam from the tube wall. In the high heat load zone reheat steam heating surface, such as the outlet section of the wall temperature is higher. Used here