回转式空气预热器风烟焓增模型及其效率分析

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

回转式空气预热器作为大型电站锅炉的尾部受热面,分析其漏风量与机组效率之间的关系对整个密封系统改造具有现实的指导意义。基于工质热力循环,提出回转式空气预热器风烟焓增模型,分析回转式空气预热器的热力过程中漏风率对机组效率的影响,定量验证热端面的漏风量对机组效率的影响程度,得出漏风总量减小,并不能保证机组效率提高的初步结论。最后利用回转式空气预热器风烟焓增模型分析某电厂采用“VN”密封技术改造的合理性。

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.