【摘要】 喷雾液滴蒸发特性是实现电厂脱硫废水零排放烟气蒸发技术的关键。利用数值模拟的方法对气液两相流过程中涉及影响液滴蒸发特性的喷雾液滴平均粒径(分布特征)、传热传质等影响因素进行分析,建立喷雾液滴群烟气蒸发传热传质模型,获得了喷雾液滴群蒸发规律及运动特征。分析结果表明:模拟喷雾粒径情况下,液滴加热迅速,完全蒸发的关键控制步骤取决于液滴表面蒸汽气相组分浓度Ci,s与烟气中蒸汽气相组分浓度Ci,∞的浓度差,相同的烟气蒸发环境下,不同粒径组都呈现出初期快速蒸发和后期缓慢蒸发2个明显的阶段,在相同最大粒径范围下(最大直径100μm),细颗粒群(平均粒径24μm)主体段蒸发时间最短(0.3 s达到80.1%的蒸发质量比),粗颗粒群(平均粒径84μm)蒸发质量比最大(0.6 s达到95%的蒸发质量比)。更多还原

【Abstract】 Evaporation characteristics of spray droplets are crucial for implementing zero discharge and smoke-gas evaporation technology of desulfurization wastewater in power plants.The factors that affect evaporation characteristics in the process of the gas-liquid two-phase flow,such as average particle size(distribution characteristics) of spray droplets and heat and mass transfer,were analyzed with the numerical simulation method.A model of heat and mass transfer for the smoke and gas evaporation of spray droplet groups was established.Also,the evaporation rules and movement features of spray droplet groups were obtained.The results show that in the situation with simulated spray particle size,the heating process of droplets is quick; the key for complete evaporation depends on the gradient between the gas-phase component concentration Ci,sof vapor on the surface of the droplet and that of vapor in the smoke,namely Ci,∞,In the same gas and smoke evaporation environment,there are two distinct phases for particle groups with different sizes,namely quick evaporation at preliminary phase and slow evaporation at later phase.In the same range of maximum particle sizes(the maximum diameter is 100 μm),the main section of fine particle groups(the average particle diameter is 24 μm) have the shortest evaporation time(the evaporation ratio reaches 80.1% within 0.3 s),while the coarse particle groups(the average particle diameter is 84 μm) have the largest evaporation ratio(the evaporation ratio reaches 95% within 0.6 s).更多还原