The Physics

The Gas Cloud Imaging (GCI) camera technology is based on infrared absorption spectroscopy; different gases have different absorption signatures, which are distinct within the infrared region. Figure 1 shows absorption signatures for three example hydrocarbon gases.

Most hydrocarbons show a strong absorption feature in the 3.2 to 3.5 um range due to a C-H molecular stretching mode centered there—this is the “functional group” spectral region for hydrocarbon gases. The longwave spectral region (7.5 – 14 um), on the other hand, is called the “fingerprint region” due to the fact that each gas species demonstrates a substantially different spectral shape. Most infrared gas detection cameras operate only in the mid-wave infrared range (functional group region), the GCI, however, operates in the long-wave infrared, making it possible to differentiate and quantify.

Rebellion Photonics is the only company able to offer a real-time continuous monitoring and alarming system because we have truly unique hardware. While conventional spectral cameras acquire an image by slowly scanning across a scene, the GCI acquires an image, and the spectral signature at each pixel, simultaneously. Figure 2 provides a visual comparison between the two methods. Not only does Rebellion’s hardware allow for faster measurement, but it also improves sensitivity, so that measurements that were previously starved for light are now possible.

Unlike infrared cameras, Rebellion’s GCI not only detects gases in the infrared but also their unique spectral signature. This allows the system to automatically remove false alarms such as steam, rain, snow, clouds, moving people, cars, etc. Each of these sources generates an emission/absorption signature that is substantially different from that of the hydrocarbon gases—their “fingerprints” are different.

The Rebellion Difference

The standard technology for continuous hydrocarbon leak detection is currently a mesh network of point monitoring sensors. While sensitive at very short range, they cannot provide details about the leak source or plume trajectory. Plus, they require the gas plume to physically reach the sensor, which often occurs long after the leak has started. Just one of our Gas Cloud Imaging (GCI) cameras is equivalent to over 4 million line detectors at equivalent sensitivities, allowing your operators to detect leaks faster and more efficiently than ever before.

Infrared cameras are gaining in popularity but have their own pitfalls. They cannot be used for continuous monitoring because all of them require human interpretation to determine the presence of a gas cloud. For example, infrared cameras cannot differentiate between steam and other gases, which leads to many false alarms. Furthermore, the infrared camera systems cannot determine the concentration of the gas, and therefore cannot be calibrated to alarm only at specific thresholds.

Rebellion Photonics’ Gas Cloud Imaging system is a one-of-a-kind, fully automated gas leak detection system that is compatible with all major DCS and alarm systems. The snapshot GCI system utilizes proprietary hyperspectral imaging technology with advanced detection algorithms to pinpoint and quantify leaks. With the ability to distinguish between a huge variety of chemicals, our GCI system is the next generation for leak detection and monitoring at all points of the petrochemical industry.