电厂锅炉单耗分析模型及其应用

Analysis Model for Unit Consumption of Power Boilers and its Application

根据单耗分析理论,将锅炉各受热面的工质吸热量视为不同的热产品,分析生产这些热产品所经过的从燃料到理论燃烧温度下的烟气热流,再到实际燃烧放热温度下的烟气热流,最后到热产品具有的工质热流共3个不可逆热力学过程及其附加燃料单耗,建立了一套完整的电厂锅炉单耗分析模型;并针对某超临界机组系统及其热力参数,在热力计算的基础上,进行了锅炉单耗分析.结果表明:工质在省煤器吸热获得热流是最小的,其效率最低;从理论上证明了锅炉省煤器的概念名不副实,它的存在成为燃煤火电机组发电效率进一步提高的制约因素.

Based on the theory of unit consumption analysis and taking the heat loads of various boiler heat surfaces as different heat products, a complete unit consumption analysis model has been set up by studying following three irreversible thermodynamic processes and their additional unit consumption of fuel, such as from the fuel exergy to heat exergy in gas at theoretical combustion temperature, then to heat exergy in gas at actually exothermic temperature, and finally to heat exergy in heat products. The model has been applied to the unit consumption analysis for an ultra supercritical boiler on the basis of thermal calculation. Results show that among all the heat exchangers, the heat exergy obtained by working medium from boiler economizer is the least, and its exergy efficiency is accordingly the lowest, which proves boiler economizer to be most uneconomic, indicating that the boiler economizer actually restricts the improvement of generating efficiency of fossil fuel-fired power units.