冷凝式空气加热器回收燃天然气锅炉排烟余热的分析

Analysis of Reclaiming Residual Heat of the Flue Gas of Gas-fired Boiler with a Condensing Air Heat Exchanger

文章对用空气来回收燃气锅炉排烟中水蒸气汽化潜热的冷凝式空气加热器,以加热器内烟气中的水蒸气开始冷凝处的烟气和空气的温差Δtx为变量,计算分析了锅炉最终排烟温度、加热的空气量、空气回收的热量、锅炉热效率与加热器面积大小变化的关系,为选择利用空气来回收燃气锅炉汽化潜热提供理论依据。以陕北天然气为例,如果将30℃的空气加热到120℃,计算结果表明,温差Δtx从25℃减少到0℃时,最终排烟温度略微降低约2℃,相应的加热的空气量增大1.5倍,而加热器的面积急剧增大到无穷大,锅炉效率提高的极限为4.67%,此时潜热占总回收热量的28.6%。

In this paper,for condensing air heat exchanger which reclaim latent heat of the exit flue gas of gas -fired boiler by air,At, ,which is the temperature difference of the flue gas and the air on the point where water vapor of the exit flue gas begin to condense in the heat exchanger,is used as variable, the variational relation of the last exist flue gas temperature, the quantity of air heated, heat recovered by air, the thermal efficiency of boiler and heat exchanger area is analyzed and calculated. It can provide the scientific basis for reclaiming the steam latent heat of gas - fired boiler with air. For a Shanbei natural - gas - fired boiler,when the air temperature is heated from 30℃ to 120℃ and the temperature difference △tx is reduced from 25℃ to 0℃ ,the calculational result show that the last exist flue gas temperature drop about 2℃ ,the heated air quantity is increased 1.5 times, the heat exchanger area rapidly increased to infinitude, here the high -point of thermal efficiency of boiler is increased by 4.67%, rovered latent heat is 28.6% of total amount of recovered heat.