增压富氧煤燃烧烟气凝结换热的计算

摘要

For the convective condensation heat transfer of flue gas with a few water vapors produced by pressurized oxy-coal combustion in vertical tube, investigation and calculation were carried out by theoretical analyzing method. Heat transfer mathematical model was set up by modified film model and Nusselts condensation theory. Calculations were performed for condensation heat transfer at different wall temperatures, Reynolds numbers and water vapor fractions. Results show that with the increase of wall temperature, the condensation rate of flue gas, heat flux and condensation film thickness decrease. And with the increase of Reynolds number of the mixture gas, the condensation rate of flue gas and heat flux increase too, while the condensation film thickness decrease. With the decrease of water vapor fraction,the condensation rate of flue gas and heat flux decrease too, while the decrease of condensation film thickness is not obvious.%针对含有少量水蒸气的增压富氧煤燃烧产生的烟气在竖直管内的对流凝结换热进行了分析研究.利用修正的膜模型与Nusselt凝结理论建立了换热数学模型,并对不同壁面温度、不同雷诺数和不同水蒸气份额下烟气的凝结换热进行了计算.结果表明:壁面温度升高时,烟气的凝结速率、换热流率和凝结液膜的厚度均减小;混合气体的雷诺数增大时,烟气的凝结速率和换热流率增大,凝结液膜的厚度减小;烟气中水蒸气的份额减小时,烟气的凝结速率和换热流率减小,凝结液膜的厚度减小不明显.