ObjectiveThe petrochemical industry is one of the key industries to promote the high-quality development of China's economy. Petroleum gas is colorless and odorless, so it is not easy to be detected by the staff when it leaks in small amounts, and there is a potential safety hazard. In recent years, petrochemical enterprises have an increasing demand for detection and location of petroleum gas leaks, and at the same time, they have put forward the detection requirements of high reliability, high sensitivity and high stability, which has promoted the research and development of related technologies and instruments of high-performance gas leak detection equipment to become the focus of research at home and abroad. Infrared spectral imaging technology has attracted extensive attention in the field of oil and gas leak detection technology due to its advantages of large range, long distance, rapid location of leakage source, and dynamic and intuitive vision. At abroad, although the advanced infrared spectral imaging system has excellent performance, its key technologies and products are expensive, and some technologies are blocked. At home, although progress has been made in the research of infrared spectral imaging technology, there are still challenges in achieving rapid response and automatic detection, reducing system cost, and improving system detection sensitivity and accuracy. Therefore, it is necessary to study the infrared spectral imaging detection components for oil and gas leaks.
MethodsAccording to the specific needs of the petrochemical industry for oil and gas leakage detection technology, the principle of infrared spectral imaging technology is applied to carry out the research of spectral imaging detection components. Through the analysis of the test principle and the screening of petroleum gas spectral lines, the target study band was determined (Fig.2). Based on the spectroscopic characteristics of the miniature multi-order Fabry-Perot (F-P) filter, combined with high-precision exponential lithography and etching processes (Fig.7), a multi-channel bandpass filter covering the long-wave infrared spectrum was designed and developed. Combined with the application scenario of oil and gas leak detection, the selection of image sensors and device coupling were completed (Fig.9), and finally a set of infrared spectral imaging detection components for oil and gas leak detection (Fig.10) was developed and tested and evaluated (Fig.12). The imaging detection component was used to build a detection system (Fig.13) to detect the standard gas concentration of methane, the main component of oil and gas. The theoretical detection limit concentration of the system was obtained through data processing and analysis (Fig.17).
Results and DiscussionsAn 8-12 μm long-wave infrared F-P cavity filter was designed (Fig.4), and the device was fabricated by high-precision exponential lithography and etching (Fig.7). Finally, an infrared spectral imaging detection component with more than 10 spectral bands, a spectral range of 8-12 μm, and a spectral resolution better than 0.5 μm was obtained (Fig.10). A petroleum gas leak detection system was built, and the system calibration was completed by detecting standard gases, and the theoretical detection limit concentration of the system reached 5.4% (Fig.17).
ConclusionsInfrared spectral imaging detection technology has shown great potential in the field of oil and gas leak detection due to its high efficiency, accuracy and non-contact characteristics. Based on the semiconductor processing technology, the thin film structure of the F-P cavity of the progressive cavity was designed, and the filter of the long-wave infrared band progressive cavity was prepared by applying the wide-response narrow-band high extinction ratio filtering technology and high-precision exponential lithography etching technology. It has the advantages of low cost and high efficiency in mass production. Combined with the application scenario of oil and gas leakage detection, the image sensor is selected. The bonding scheme of the long-wave infrared spectral multi-channel bandpass filter and the uncooled vanadium oxide long-wavelength surface array detector was designed, and finally a set of infrared spectral imaging and detection components for oil and gas leakage was developed, with more than 10 spectral bands, the spectral range covering 8-12 μm, and the spectral resolution better than 0.5 μm. The imaging detection component is used to detect the main components of oil and gas as standard gases, and the theoretical detection limit concentration of the system reaches 5.4%. It provides strong support for the further research and development of spectral monitoring technology and equipment for the leakage of oil and gas hazardous chemicals suitable for enterprise sites.