新型电容式蒸汽湿度传感器结构设计

针对高温高压湿蒸汽的湿度测量难度大、准确度低的难点,根据蒸汽与水的介电常数差异较大的特点,利用电容法测量湿度的原理,设计了一种同轴式圆筒形电容式传感器,可实现蒸汽湿度的在线测量。利用集成定时器NE555芯片,设计了外部测量电路对湿度信号进行测量,测量电路将电容量的变化转换成频率值,通过输出频率来反映蒸汽湿度。经标定后,该传感器既可直接测量气体的湿度,又可测量固体的水分含量。

Structure design of novel type capacitance sensor for steam humidity

In view of the character that humidity measurement for steam with high temperature and pressure is difficult and inaccurate, a coaxial cylindrical capacitance sensor is developed by capacitance method based on the fact that water and steam have great different permitfivities. By means of this sensor,on-line measurement of the steam humidity can be realized. The measuring circuit made with timer NE555 can transform the capacitance to frequency output, and then reflect the steam humidity with the frequency. The sensor can measure not only gas humidity but also the water content of solid materials after serious calibration.