A sensitive carbon monoxide sensor for industrial process control based on laser absorption spectroscopy with a 2.3 μm distributed feedback laser

Carbon monoxide (CO) is a ubiquitous atmospheric trace gas produced by natural and anthropogenic sources. It can be used as a quantitative marker to help us understand the different production processes. A near-infrared laser absorption spectroscopy of 2.3 mu m based in-situ, real-time and continuous CO sensor equipment is developed for the exhaust pipeline of furnace. High sensitivity is accomplished utilizing the ratio between the second and first harmonic signals detection (WMS-2f/1f). The analyzer is housed in an explosion-proof enclosure and installed at both sides of the pipeline with a diameter of 2.1 m. The measured gas temperature inside the pipeline reaches around 400 K. The results primarily show a more linear response and less error, the measurement precision and the minimum detection limit are 0.42 ppm and 1.29 ppm (1 sigma), simultaneously. Evaluation of the data suggested a dynamic range from 3.87 ppm to 1.3% based on the 3 sigma rule and maximum absorbance of one. An operator can analyze the industrial production process clearly, that is, the measured CO concentration is negatively correlated with excess oxygen (O-2) by observing the measurement results within 10 h. Meanwhile, the measurements of the real targets show that the sensor has great applicability and potential for exhaust pipeline and combustion control systems.

Automated summary

This article introduces a CO sensor based on infrared absorption spectroscopy for measuring exhaust gases in furnace pipelines. The sensor has high sensitivity and linear response, and can be used to analyze industrial production processes. It has great applicability and potential for use in exhaust pipelines and combustion control systems.