Laser-based Remote Sensing of Gas Distribution Leaks

摘要

A novel, semi-conductor laser-based remote sensing technique for the detection of natural gas leaks at the ground level is described. A dual-laser, differential absorption arrangement is used to inspect a horizontal line on the surface similar to a bar code scanner. The real-time line-scan display is co-aligned and overlaid on a conventional video camera image of the area under inspection. This allows the operator to see the exact position on the surface being probed. The system is designed to detect gas leaks with methane concentrations in the 5-10 ppm-m range at distances up to 30 meters. Preliminary performance results of a prototype Laser Line-scan Camera (LLC) will be reported in the paper. The field-of-view of the prototype LLC system emanates from a rotary turret from the top of a van, which allows to detect either forward or sideways leaks from natural gas distribution systems. Initial test results are for controlled releases of methane gas at various distances from the van in the backyard. Leak detection limits versus van speed are also investigated and will be reported.