Study on the Influence Law of Gas Pressure on Methane Concentration Measurement
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Shen Kai, Liu Yanbao
The measurement accuracy of the infrared methane concentration sensor is greatly affected by the gas pressure. There is a large error between the measured value and the true value, when measuring under negative pressure of the underground gas drainage pipeline. The Methane concentration measurement experiment under negative pressure of 40～90KPa (absolute pressure) has been conducted in laboratory. The influence of gas pressure on methane concentration measurement was analyzed by the results. And then a nonlinear-segmentation pressure compensation model for negative pressure was worked out according to experiment data. The errors of measured methane concentration value after compensation were under ±0.05%CH4 in the range of 0 to 1%CH4 and under ±7.0% of truth-value in the range of 1% to 100%CH4. The research results show that the pressure compensation model could adapt the negative pressure of gas extraction system, and meet the requirements of methane concentration measurement in the pipe for gas extraction.
Gas pressure, gas extraction, methane concentration, influence law, compensation model