含盐脱硫废水液滴群在低温烟道蒸发特性数值模拟研究

Numerical Simulation of Evaporation Characteristics for Salt-containing Desulfurization Wastewater Droplets in Low Temperature Flue

以含盐脱硫废水在某燃煤电厂330 MW机组空气预热器后烟道的喷雾蒸发过程为研究对象,采用离散相模型研究气液两相流动、传热传质和雾化液滴的蒸发,分析了烟气温度、烟气流速、脱硫废水含盐量、液滴直径对蒸发时间,喷雾含水量、蒸发质量的影响。研究表明:含盐脱硫废水蒸发末期,由于水与结晶盐的相互作用,蒸发速率减小;脱硫废水含盐量越高,蒸发越快,盐分由1.0增加至2.0%,蒸发时间减少0.02 s;液滴直径越大,蒸发结晶的固体越大,相同直径下含盐液滴蒸发时间比不含盐液滴蒸发越短;与不含盐液滴相比,液滴直径为60μm时两者完全蒸发时间基本相当,但液滴粒径180μm时,含盐液滴完全蒸发时间比不含盐液滴缩短0.3 s;温度越高,不同含盐量的液滴完全蒸发时间越接近。

Taking the salt-containing desulfurization wastewater spray evaporation process for research objects in the 330 MW coal-fired power plant flue duct after the preheater,Gas-liquid two phase flow,heat and mass transfer and atomized droplet evaporation were simulated by using discrete phase model(DPM).The relationship between evaporation time,spray water contenting,evaporation quality and droplet initial diameter,flue gas temperature,salt contenting in desulfurization wastewater and flue gas velocity was studied.The results show that the evaporation rate decreases at the end of desulfurization wastewater evaporation due to the interaction between water and crystalline salts.The higher the salt content of desulfurization wastewater,the faster the evaporation,salt content decreased from 1.0 to 2.0%and evaporation time decreased by 0.02 s.The larger the droplet diameter is,the larger the solid crystallized by evaporation is.The evaporation time of Saline droplets is shorter than non-saline droplets under the same diameter.Compared with the non-saline droplets,the evaporation time is almost the same when the diameter of the droplets is 60μm,but when the diameter of the droplets is 180 microns,the evaporation time of the Saline droplets is 0.3 s shorter than non-saline droplets.The higher temperature is,the closer evaporation time of droplets with different salt content is.