Grantee Research Project Results
Final Report: Handheld Laser-Based Sensor for Remote Detection of Gas Leaks
EPA Contract Number: 68D99063Title: Handheld Laser-Based Sensor for Remote Detection of Gas Leaks
Investigators: Frish, Michael B.
Small Business: Physical Sciences Inc.
EPA Contact:
Phase: I
Project Period: September 1, 1999 through March 1, 2000
Project Amount: $69,997
RFA: Small Business Innovation Research (SBIR) - Phase I (1999) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , SBIR - Monitoring , Small Business Innovation Research (SBIR)
Description:
This project demonstrated the feasibility of developing a new hand-held optical tool which will facilitate detection and location of toxic or hazardous gas leaks in petrochemical refineries, chemical processing plants, natural gas production facilities, and natural gas distribution pipelines. The tool is based on Tunable Diode Laser Absorption Spectroscopy (TDLAS), a sensing technology that is rapidly gaining acceptance in industrial environments for detecting releases of selected gases. When fully engineered the tool is expected to resemble a large flashlight. It illuminates a distant surface with laser light and measures the amount of target gas along the line of sight transited by the laser beam.Unlike other types of portable gas detectors, this laser-based device does not need to be immersed within the gas leak. This is of value in, for example, chemical and petrochemical settings that operate tanks and pipelines containing hydrogen fluoride, hydrogen sulfide, ammonia, or methane. The plant operator may receive an indication from an area sensor that a leak has occurred, but the sensor cannot pinpoint the source of the leak. The novel laser-based sensor would allow plant personnel to isolate the source of a leak while remaining outside the perimeter of the processing area where the hazardous gas is highly concentrated. Thus, the risk to plant personnel is reduced, and by enhancing the speed with which leaks can be located, the risk of an incipient failure becoming a catastrophic failure is reduced significantly.
Another application for the hand-held TDLAS gas sensor is municipal natural gas pipeline leak surveying. Natural gas distribution and service companies continually survey gas pipelines to detect small leaks and correct them before becoming dangerous. Currently, this process is labor intensive, requiring an individual to either drive or walk over every buried natural gas pipe. A laser-based device that can rapidly survey off-road pipelines has great appeal because it would eliminate or minimize the need to walk along these pipes. The device could also be valuable for usage by first responders to determine if an area is safe for occupation or to localize the source of a leak after natural disasters causing pipeline ruptures. The specific technical objective of the Phase I research and development effort was to experimentally demonstrate that a portable TDLAS transceiver, sensing laser light that is transmitted through a gas cloud and scattered back to the transceiver from ordinary topographic surfaces beyond the gas cloud, without the use of a retroreflector or retroreflective material, can usefully sense gas leaks. Quantitatively, the goal was to demonstrate that the instrument can sense a specific target gas with a path-integrated concentration yielding a laser absorbance on the order of about 2 x 10-5, by detecting from a distance of about 20 m only the laser radiation scattered from surfaces located behind the leak source without a dedicated retroreflector. This corresponds to an ability to locate toxic or hazardous gas leaks resulting in path-integrated concentrations of, for example, 0.4 ppm-m of hydrogen fluoride, 2 ppm-m of methane, or 40 ppm-m of hydrogen sulfide. Such sensitive detection is more than adequate for many of the envisioned applications.
To perform these experimental evaluations, a breadboard prototype of the device was built. The prototype was assembled using primarily TDLAS equipment already available in Physical Sciences Inc.'s (PSI's) laboratory, and was suitable for evaluation of key parameters including signal-to-noise ratio as a function of distance between the transceiver and illuminated surface, sensitivity to target gas as a function of distance, and linearity of response to target gas concentration. The sensor was built of three primary components: 1) a laser source and control electronics; 2) a transceiver; and 3) receiver electronics. The laser source and control electronics, as well as the receiver electronics, were assembled primarily from commercially-available laboratory equipment. The Phase I effort focused on the design, assembly, and testing of an optical transceiver that could be built in a lightweight and compact fashion while providing the desired sensitivity, and evaluating the feasibility of manufacturing a product based on this design at a cost acceptable to the target markets.
The breadboard apparatus was used for: 1) demonstrating that the detected optical power behaves according to predictions; 2) demonstrating linear response to target gas concentration; and 3) determining the minimum measurable target gas concentration at a selected distance. The ability to detect a methane plume from a simulated pipe leak against a variety of backgrounds was also demonstrated.
Summary/Accomplishments (Outputs/Outcomes):
The Phase I work showed that it is indeed possible to develop a hand-held TDLAS system that projects a laser beam onto surface or objects located up to 20 m away, receives laser light backscattered from that target, and deduces the concentration of a specific gas within the optical path. The breadboard hand-held TDLAS transceiver demonstrated a noise equivalent spectral absorbance of about 8 x 10-5.While significant improvement is anticipated in advanced designs, the system signal-to-noise ratio achieved in Phase I exceeds the requirements for the envisioned applications. For example, the minimum path-integrated concentration of methane that can be detected with the Phase I apparatus in 1 second with unity signal-to-noise ratio is less than 10 ppm-m. The ability was demonstrated to use the device to unambiguously detect methane leaks from a point outdoor source, with the laser beam scattered from a wide variety of topographic surfaces.
Estimates of manufacturing costs for producing this device in volumes suitable for the envisioned markets show that a sales price of less than $10,000 per unit is feasible. A brief survey of the target market indicates that this price should be acceptable, providing a rapid payback because of reductions in labor costs when the sensor is utilized.
Conclusions:
The Phase I technical effort has demonstrated the feasibility of developing the innovative TDLAS hand-held optical tool for detecting and locating hazardous gas leaks, and the Phase I commercialization study has identified a significant market for this technology. This work has provided a solid foundation for advancing to Phases II and III. Relationships have been formed with potential customers for this technology and with other firms that wish to manufacture and market the technology to those customers. These customers and manufacturers have agreed to help guide the development process and evaluate the technology during Phase II. They have further agreed to commit additional commercialization funds pending successful Phase II technical and market evaluations.Supplemental Keywords:
Leak Sensing, Leak Locating, Remote Sensing, Laser Spectroscopy, TDLAS, Natural Gas., Scientific Discipline, Air, Toxics, Ecosystem Protection/Environmental Exposure & Risk, Sustainable Industry/Business, air toxics, Chemistry, Monitoring/Modeling, Technology for Sustainable Environment, New/Innovative technologies, Engineering, Chemistry, & Physics, monitoring, remote sensing, gas detector, air pollutants, laser based emissions monitoring, HAPS, hazardous air pollutants, power plants, detect, toxic emissions, hazardous emissions, air pollution, optical sensor, gas leak, optical detectors, industrial air pollution, portable device, industrial boilers, laser based optical sensor, hazardous air pollutants (HAPs), spectroscopic, power generation , laser absorption sensors, measure, sensor technology, power generation, sensorsSBIR Phase II:
Handheld Laser-Based Sensor for Remote Detection of Gas LeaksThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.