超临界循环流化床锅炉屏式过热器吸热量偏差特性研究

Study on the Heat Absorption Deviation Characteristics of the Platen Superheaters in the Supercritical Circulating Fluidized Bed Boiler

超临界循环流化床(circulating fluidized bed,CFB)燃烧技术作为一种具有综合性优点的技术,被广泛应用,但其炉膛中屏式过热器爆管泄漏问题频繁发生,故有必要对其水动力特性及吸热量偏差特性进行研究分析。根据针对超临界CFB锅炉炉膛内屏式过热器所建立的复杂流动网络系统的数学模型,及屏式过热器出口汽温分布实炉测量数据,对热负荷进行反推,计算分析了河曲电厂350MW超临界CFB锅炉以及白马电厂600MW超临界CFB锅炉中屏式过热器流量分配、出口汽温分布及壁温特性,并计算得到了屏式过热器中吸热量热偏差系数分布。计算结果表明,屏式过热器吸热量及热偏差系数在近壁侧、近火侧较小,在受热面中部则二者较大,这是由于各处烟气颗粒浓度的不同而影响传热造成,对吸热量及传热系数的分析研究对超临界CFB锅炉的设计及优化改造提供了理论依据。

As a technology with comprehensive advantages, supercritical circulating fluidized bed(CFB)combustion technology is widely used. However, the leakage of the platen superheaters in the furnace frequently occurs, so it is necessary to research and analysis of thermal-hydraulic characteristics and heat absorption characteristics. According to the mathematical model of the complex flow network system established by the platen superheaters of the supercritical CFB boiler, and the actual furnace measurement data of the temperature distribution of the platen superheaters, the heat load was inversely deduced. The flow distribution, outlet steam temperature distribution and wall temperature characteristics of the platen superheaters in the 350MW supercritical CFB boiler of Hequ Power Plant and the 600MW supercritical CFB boiler of Baima Power Plant were calculated, along with the heat absorption distribution and the thermal deviation coefficient distribution. The calculation results show that the heat absorption and thermal deviation coefficient of the platen heating surface are smaller on the near wall side and the fire side, and the two are larger in the middle of the heating surface.This is due to the difference in the concentration of smoke particles. The analysis and research of heat absorption and heat transfer coefficient provide a theoretical basis for the design and optimization of supercritical CFB boilers.