高温高压蒸汽相对湿度测量

Measurement of relative humidity for high-temperature and high-pressure steam

为推广工业生产中高温高压蒸汽相对湿度测量应用与温度100℃以上相对湿度测量国际单位制(SI)溯源,对国内外高温蒸汽湿度发生、相对湿度测量工艺原理以及对应测量范围的最新研究进行了概述。通过对比测量的方式对不同测量方法之间相对湿度测量偏差与不确定度进行了平行比较,并结合相对湿度测量SI溯源与测量技术特征进行了综合分析。对比实验得出,在露点温度127℃条件下,蒸汽膨胀法与微波谐振法对比测试偏差随相对湿度的增加逐渐增大,当相对湿度达70%时,测试偏差接近4%。蒸汽凝结法与气-汽混合法在露点温度128℃、相对湿度95%条件下,测试偏差≤0.5%,不确定度≤1%。4种测量方法均实现了露点温度100℃以上高温压力蒸汽相对湿度的有效测量。

In order to promote the application of high-temperature and pressure steam relative humidity measurement in industrial production and widely develop the traceability of the International System of Units(SI) of relative humidity above 100 ℃,this article summarizes the latest research on the preparation for standard humidity of high-temperature steam,the principle of relative humidity measurement technology and the corresponding measurement range.The measurement deviation and uncertainty between different methods were compared through comparative measurement,and a comprehensive analysis was conducted based on the traceability for relative humidity measurement and the technology characteristics.The comparative experiment shows that under the dew point temperature of 127 ℃,the test deviation between the steam expansion method and the microwave resonance method gradually increases with the increase of relative humidity.When the relative humidity reaches 70%,the deviation is close to 4%.Under the condition of dew point temperature of 128 ℃ and relative humidity of 95%,the test deviation and uncertainty between steam condensation method and gas-steam mixing method are not exceed 0.5% and 1%.The four measurement methods can effectively measure the relative humidity of high temperature and pressure steam with the dew point temperature above 100 ℃.