Research on passive wide-band uncooled infrared imaging detection technology for gas leakage

Aiming at the requirements of gas detection in petroleum, petrochemical, power equipment and air pollution monitoring, some key technologies in passive uncooled gas leakage infrared imaging detection system are analyzed. Based on the gas absorption line intensity and absorption peak position in the standard infrared database, the key components such as MW and LW infrared optical lens and wide band uncooled infrared focal plane detector are optimized. Considering the imaging signal-to-noise ratio and signal contrast, the filter used in several typical gas detections is analyzed, and an online and handheld gas leakage infrared imaging detection system capable of detecting multiple gases is designed. Theoretically, it is possible to detect gas with characteristic absorption in the range of 3-14 μm. The imaging effects of carbon dioxide gas, methane gas and sulfur hexafluoride gas with absorption peaks in MW and LW bands were measured. The test results show that the uncooled infrared gas detection system designed in this paper not only has good imaging detection ability for sulfur hexafluoride gas and ethylene gas (near 10.5 μm) with large absorption intensity and absorption peak in conventional LW band, but also for methane gas (near 7.5μm or 3.3μm) and carbon dioxide gas (near 4.2 μm) with absorption peak in unconventional LW band. In the laboratory environment, with the black body as the background, the gas flow rate is controlled by the gas mass flow meter to observe the imaging detection effects under different temperature differences and different flow rates. When the target and background temperature difference is 5K, the gas detection ability is ≤100mL/min.