提出一种降膜直接接触式烟气余热回收方案。在喷淋区布置多块竖直降膜板，低温喷淋水在上方喷下来，在降膜板上形成液膜，在重力的作用下向下流动。饱和湿空气向上流动，与液膜直接接触，实现热质交换。采用数值模拟的方法研究喷淋水的流量、湿空气的流速、湿空气的温度和降膜板的高度等对余热回收效果的影响。结果表明：增加喷淋水流量和降膜板高度或降低湿空气流速和进口温度有利于提高换热效率和冷凝率。搭建了降膜直接接触余热回收实验台，并与空喷淋塔进行了比较。在实验范围内，与空喷淋塔相比，降膜直接接触余热回收使换热效率提高20.0%～23.2%，模拟与实验数据的最大误差为3.1%，证明模拟结果可靠。

A heat recovery method by using falling film direct contact method is presented.Several vertical plates for falling film are arranged in the spray field.Low temperature water sprays on the upper of the plates.The water film spreads on the plate and flows down under the gravity.The saturated moist air flows up and directly contacts with the water film.So the heat and mass are exchanged.A numerical simulation is adopted to research the effects of spray water flow,moist air velocity,moist air temperature,and plate height on the heat recovery.The results show that the increase of the spray water flow and the plate height or the decrease of the moist air velocity and the moist air temperature can improve the heat transfer rate and the condensation rate.An experimental system for examining the heat recovery of the falling film and direct contact method is set up.The heat recovery of a hollow spray tower is considered.The numerical results show that the heat recovery of the falling film and direct contact method can be improved 20.0%～23.2% in comparison with the hollow spray tower in the present experimental range.The maximum difference between the model and the experiment is 3.1%,hence the numerical method is validated.

TK124

国家自然科学基金(51576059)；河北省自然科学基金(E2015202272)