回转式空气预热器风烟焓增模型及其效率分析

1前言回转式空气预热器的缺点是漏风率大,漏风使能量损耗,回转式空气预热器效率由于漏风而降低,整个机组的效率也受到影响。在1963年,Frass和Ozisik指出1],空气预热器的漏风量将影响锅炉效率和汽轮机的输出功率。Bejan等人提出漏风量直接影响的是空气预热器换热效率2],对机组

An Air-and-Flue Gas Enthalpy-increase Model for a Rotary Air Preheater and an Analysis of the Preheater Efficiency

Rotary air preheaters usually serve as tail heating surfaces of large-sized utility boilers.An analysis of the relationship between their air leakage rate and boiler unit efficiency plays a major role in guiding the modification of the whole seal system for a preheater.Based on the thermodynamic cycle of a working medium,an air and flue gas enthalpy-increase model for a rotary air-preheater is presented for analyzing the impact of air leakage rate in preheater thermal process on the boiler unit efficiency.Furthermore,the extent of the impact of air leakage from the hot end on the boiler unit efficiency is verified quantitatively.A preliminary conclusion has been reached that the reduction of total air leakage can not guarantee an increase in boiler unit efficiency.Finally,the rationality of a technical modification for a power plant by adopting "VN" seals is analyzed by using the air and flue gas enthalpy-increase model of the rotary air preheater.