选择性非催化还原脱硝温度窗口内尿素液滴的蒸发和转化特性

Evaporation and Conversion Characterizations of Urea-water-solution Droplets Within the Temperature Window for SNCR DeNO_x

主要围绕SNCR温度区间内尿素液滴的蒸发和转化特性开展研究。建立了尿素液滴蒸发和转化过程的在线观测实验系统和数据处理方法,可定量化描述蒸发和转化过程中的尿素液滴粒径变化。实验发现,尿素液滴在高温环境中主要经历了水分蒸发和尿素分解两个阶段,水分蒸发阶段的特征与单质水基本一致,尿素分解阶段的特征与单质尿素基本一致,在尿素分解阶段伴随有微爆现象。温度、尿素溶液浓度的增加会缩短尿素液滴第1阶段的标准化蒸发时间,加剧第2阶段的微爆现象,而液滴初始粒径对第1阶段的影响较小。

This study focused on the evaporation and conversion process of urea aqueous solution droplet and the process characterization in the temperature range for selective non-catalytic reduction（SNCR）.An in-situ observation system was built to study the evaporation and conversion of urea aqueous solution droplet.Based on the analysis of droplet photo,the droplet diameter variation can be quantified.The evaporation and conversion process of urea aqueous solution droplet can be divided into two stages.The first stage（water evaporation） is consistent with the simple substance water and the second stage is basically the same characteristics as evaporation and decomposition of pure urea particle.Increase in evaporation temperature or solution concentration shortens the characteristic time of the first stage and promotes the microexplosion in the second stage.Change in initial droplet size has little influence on the characteristics of the evaporation process in the first stage.