应用于天然气的近红外CO气体分析系统的实验研究

Experimental research on near-infrared CO gas analysis system for natural gas

基于CO气体分子在1.56μm处的泛频吸收带,结合波长调制技术和谐波检测技术,采用长光程气体吸收池,研制了一种应用于天然气的CO浓度分析系统。该系统主要由激光器驱动模块(压控恒流源和温度控制电路)、Herriot型气体吸收池气室、锁相放大电路等信号处理模块构成。利用混合模拟气站模拟天然气环境,配备不同标准浓度的CO气体,经实验验证,该分析系统的最低检测下限5.6 ppm(1 ppm=10^(-6)),浓度为0.05%的CO气体的相对误差小于2%;对于10%浓度的标准CO气体的相对误差小于1.8%。当被测CO气体浓度在0～100 ppm范围时,其系统检测灵敏度为0.09 mV/ppm;同采用QCL(Quantum Cascade Laser)的CO检测系统相比,该系统具有性价比高、适用于复杂油气开发场合等优势,在石油化工天然气领域具有很大的应用价值。

A CO concentration analysis system for natural gas was developed based on the diffuse absorption band of CO gas molecules at 1.56μm,combined with wavelength modulation and harmonic detection techniques.A long light path gas absorption cell was used to analyze CO concentration.The system was mainly composed of laser driving module(voltage-controlled constant current source and temperature control circuit)gas chamber of gas absorption cell and phase-locked amplifying circuit and other signal processing modules.A hybrid simulated gas station developed by the laboratory was used to simulate the natural gas background with different standard concentrations of CO gas.The experimental results show that the minimum detection limit of the system is up to 5.6 ppm;the relative error of CO gas with 0.05%concentration is less than 2;and the relative error is less than 1.8%for standard CO gas with 10%concentration.When the range of CO concentration is 0-100 ppm,the detection sensitivity is 0.09 mV/ppm.Compared with the CO detection system of the quantum cascade laser,the system has the advantages of high performance-to-price ratio,suitable for complex oil and gas development,and has great application value in the field of petroleum,chemical and natural gas.