Abstract: Molten salt frozen-wall is proposed as an option for protecting the metallic walls from corrosion by a layer of frozen salt which can prevent gas and liquid medium contacting with metallic wall. Accurate monitoring and controlling the thickness of frozen wall is the key for its successful application. Different on-line thickness detection methods were studied in the condition of frozen-wall forming and maintaining,and results were compared and analyzed with the thickness measured by mechanical caliper. For temperature gradient calculation method the result is more accurately in a state of balance than that in the unsteady condition,but it need to layout applicable thermocouples. The thickness of frozen wall also could be detected by cooling heat calculation method,which using outside heat exchange amount and metal wall temperature,its advantage is that there is no need for additional equipment,but its stability and accuracy depends on the amount of cooling heat,Online image can reflect thickness of frozen wall visual,but it need to be equipped with stable and reliable high temperature camera system. Because molten salt frozen-wall will be used in airtight condition which there is no water and oxygen,these on-line methods should be further researched and evaluated in the real system.

Key words: molten salt, corrosion, frozen-wall, heat transfer, measurement

摘要： 熔盐冷冻壁防腐蚀技术是采用凝固熔盐层阻止气液介质与金属器壁直接接触，冷冻壁厚度的准确监测及控制是其成功应用的关键。本文以混合硝酸盐熔盐为实验介质，研究了冷冻壁形成及维持过程中不同在线厚度监测方法，并与机械卡尺的直接测量值进行对比分析。结果表明，温度梯度推算法在非稳态及厚度较小时误差较大，在平衡维持态时则能较准确地判定厚度，但需要设置合适的热电偶组；冷却热量推算法可通过外夹套换热量及换热壁面温度推算冷冻壁厚度，但其稳定性及准确性取决于冷却量的精确衡算，其优点是不需增加额外设备；在线图像处理法能比较直观地反映冷冻壁厚度，但需要配备稳定可靠的高温摄像系统。鉴于未来熔盐冷冻壁应用是在无水无氧密闭容器中，这几种在线监测方法在真实高温熔盐化学体系的适用性还有待于进一步研究和评估。

关键词: 熔盐, 腐蚀, 冷冻壁, 传热, 测量