烟气热回收与净化耦合系统换热与吸收性能实验研究

Experimental Study on Heat Transfer and Absorption Performance of Flue Gas Heat Recovery and Purification Coupling System

节能提效和减污降碳是实现碳达峰与碳中和的重要技术路径,针对排烟热损失大、烟气净化过程中能耗物耗高、运行成本高等问题,搭建烟气热回收与净化耦合实验系统,研究烟气与吸收液直接接触换热及吸收净化过程中,吸收液分别为水与NaOH溶液时,不同液气比和被加热水流量对烟气热回收和吸收净化性能的影响及其规律。结果表明:在烟气平均进口温度为146℃、平均水蒸气质量含量6.3%、液气比3~11 L/m^(3)条件下,吸收液为水时烟温降到41.3~47.2℃,烟气余热回收的节能率为8.9%~12.1%,随被加热水流量增大而提高,随液气比增大提高到一定程度后趋于平缓;在烟气进口SO_(2)质量浓度为730 mg/m^(3)、吸收液分别为水和NaOH溶液时,对SO_(2)吸收率分别为21.2%~46%和43.9%~60.9%,吸收率和余热回收的节能率均随液气比增大提高到一定程度后增速变缓;烟气余热回收降低出口烟温,有助于提高烟气净化效率;应综合考虑节能与净化及水泵能耗等确定最佳液气比。实验系统兼具节能与净化功能,为烟气净化协同余热回收技术开发和工程应用提供参考。

Energy saving and efficiency improvement,pollution reduction and carbon reduction are important technical paths to achieve carbon peak and carbon neutralization.Aiming at the problems of large heat loss of flue gas,high energy and material consumption and high operation cost in the process of flue gas purification,this paper establishes a flue gas heat recovery and purification coupling experimental system to study the direct effects of different liquid gas ratio and heated water flow on flue gas heat recovery,absorption and purification performance and their laws during the direct contact heat exchange between flue gas and absorption solution,and the absorption and purification process when the absorption solution is water and NaOH solution respectively.The results show that when the average inlet temperature of flue gas is 146℃,the average water vapor mass content is 6.3%,the liquid-gas ratio is 311 L/m^(3),and when the absorption liquid is water,the flue gas temperature drops to 41.347.2℃,and the energy-saving rate of flue gas waste heat recovery is 8.9%12.1%.And itincreases with the increase of heated water flow and tends to be flat when the liquid-gas ratio increases to a certain extent.When the SO_(2) concentration at the flue gas inlet is 730 mg/m^(3) and the absorption solution is water and NaOH solution respectively,the SO_(2) absorption rate is 21.2%46%and 43.9%60.9%respectively.The absorption rate and energy-saving rate of waste heat recovery increase to a certain extent with the increase of liquid-gas ratio,and then the growth rate slows down.Flue gas waste heat recovery reduces the outlet flue gas temperature,which helps to improve the flue gas purification efficiency.The optimal liquid gas ratio shall be determined by comprehensively considering energy saving,purification and water pump energy consumption.The experimental system has the functions of energy saving and purification,which provides a reference for the development and engineering application of flue gas purification and heat recovery technology.