二次再热锅炉再热器调温方式选择研究

Study on Selection of Temperature Regulation Mode of Reheater in Double-reheat Boiler

针对投产二次再热机组锅炉再热汽温普遍低于设计值的问题,各锅炉制造厂根据自身二次再热锅炉的炉型及燃烧特点,研发了不同的再热器调温方案。对锅炉负荷、过量空气系数、给水温度、燃料性质、受热面污染情况等因素影响蒸汽温度进行介绍分析,本文以再热系统可以采用的汽温调节方式分为烟气侧调节和蒸汽侧调节两大类进行研究分析,对比介绍了2种方式下的各种调节方案,如蒸汽侧改变蒸汽的焓值来调节汽温,比较常见的是喷水减温、蒸汽旁通、汽-汽热交换器等;烟气侧调节通过改变锅炉内辐射受热面和对流受热面的吸热比例或改变流经受热面的烟气量来调节汽温,常见的有烟气挡板、改变火焰中心位置、烟气再循环等。同时,结合国内锅炉燃烧工况、入炉煤质、投资成本等综合考虑,提出适合二次再热锅炉特点的再热器调温方案,使再热器汽温能够在规定范围内波动,与设计值相差不大,再热器汽温偏低问题基本得到解决。

In view of the problem that the reheating steam temperature of the boiler of the double-reheat units in production is generally lower than the designed value,all boiler manufacturing plants have devel. oped different reheater temperature regulation schemes according to the furnace type and combustion character. istics of their own double-reheat boilerS. The factors affecting steam temperature,such as boiler load,ex. cess air coefficient,feed water temperature,fuel properties,pollution of heating surface and so on,are in. troduced and analyzed. In this paper,the steam temperature regulation modes which can be used in reheat system are divided into flue gas side regulation and steam side regulation are studied and analyzed,and two kinds of regulation scheme are compared and introduced. If the steam side changes the enthalpy value of the steam to regulate the steam temperature,the more common are the water spray temperature,steam by. pass,steam-steam heat exchanger,etc. Flue gas side regulation can adjust steam temperature by changing the heat absorption ratio of radiant heating surface and convection heating surface or changing the amount of flue gas passing through the heating surface,such as gas baffle,change the flame center location,gas recir. culation,etc.. At the same time,taking into account the domestic boiler combustion conditions,coal quality and investment cost,a reheater temperature regulation scheme that suitable for the characteristics of the re. heat boiler of double-reheat is put forward,so that the steam temperature of the reheater can fluctuate with. in a prescribed range,and it has subtle difference of the design value,the problem of low steam tempera. ture of reheater is basically solved.