严寒地区燃气锅炉烟气余热回收的计算分析

Calculation and Analysis on Recovery of the Waste Heat of the Flue Gas in Gas Boiler in Cold Region

本文以东北地区燃气供热锅炉为研究对象,对烟气余热回收进行了系统的计算分析,详细分析了天然气及其燃烧后产生烟气的组分.基于稳态分布下的烟气定值定压比热,建立了数学模型,概述了过量空气系数对烟气露点温度的影响,并计算分析了烟气经不同程度的冷凝降温后,显热与汽化潜热的回收变化.结果表明:当过量空气系数恒定时,排烟温度越低,回收热量越多,锅炉效率亦越高,但过度追求降低排烟温度则会导致经济成本的增加.

Taken the gas heating boiler in Northeast China as the research object in this paper,the systematic calculation and analysis on the recovery of waste heat from flue gas in boiler was made.The components of natural gas and its flue gas were analyzed in detail.The mathematical model was established based on constant value of specific heat at constant pressure of the flue gas under the steady state distribution.The effect of the excess air coefficient on the dew point temperature of the flue gas was outlined,and the variation of recovery sensible heat and latent heat of vaporization of the flue gas was calculated and analyzed after the flue gas cooled by different degrees of condensation.The results show that while the excess air coefficient is constant,the lower the exhaust flue gas temperature,the more heat recovery and the higher the boiler efficiency is,but the excessive pursuit of reducing exhaust flue gas temperature will lead to the increase of economic costs.