电容传感器动态检测金属锡熔融液面的应用研究

Application Study of Capacitance Sensor in Dynamic Measuring Molten Tin Surface

在综述电容传感器工作原理和结构特点的基础上,依据传热学原理,提出了用陶瓷作为电容测微仪三层电极绝缘材料的新方法,提高了高频(4 MHz)平面变极间距型电容传感器在高温(700℃)环境下对于熔融态金属液面检测的灵敏度和准确度。通过对大量的动态试验测试数据的分析和计算,建立了电容传感器的输出信号与其相对锡液面的高度之间的对应关系。通过对电容传感器测试系统进行非线性补偿,解决了浮法玻璃在线CVD镀膜反应器相对于锡槽内高温熔融态锡液面位置在线测量的难题。测试结果表明,在熔融态金属锡液上方25 mm的有效量程内,动态测量的误差可达到±0.1 mm,系统工作可靠。

The working principle and the structure characteristic of the capacitance sensors have been summarized. Based upon the principle of heat conduction a new method that the pottery is used for the insulation material between the three electrodes of the capacitance sensor is put forward. So the accuracy and the sensitivity for the measurement of a molten tin surface are increased with the new capacitance sensor at the environment of high temperature of 700℃. Through analysis and calculation on a large number of dynamic measuring data, the corresponding relationship between the output signal of the capacitance sensor and the molten tin surface is established. A non-linear compensation is applied to the capacitance sensor system, therefore a key measuring problem that how to measure the gap between a CVD coating reactor and the molten tin surface in the production of floating glass coating has been solved. The test result proves that the dynamic measuring accuracy is reached 0.1 mm within the effective range of 25 mm above the molten tin surface. It also shows that the measuring system is reliable and feasible.