High sensitivity infrared camera expedites plant leak detection
A FLIR Systems infrared camera for detecting gas leaks has attracted interest, with around 150 units sold since marketing started in the US in mid-2005 and in Europe last fall.
Most of the FLIR ThermaCAM GasFindIR systems sold have gone to refineries and petrochemical plants. Major oil and gas companies are among those that have acquired the camera, including BP, ExxonMobil, Pemex, Petro-Canada, and Shell. But operators of offshore installations and reception/processing terminals for gas from offshore fields also are potential customers.
According to product manager Johan Tegstam, the three main reasons for using GasFindIR are preventing product loss, safety, and protection of the environment.
Infrared imaging makes it possible to “see” gas and volatile organic compounds (VOCs) that are invisible to the human eye. This is done through the use of a spectral filter designed to transmit in the region of the infrared spectrum that coincides in wavelength with the vibrational/rotational energy transitions of VOC molecular bonds.
The camera looks for the wavelength of infrared “heat” emitted by the gas it has been set up to detect. If the gas is present, it appears in real time on the camera display as a plume of smoke, says Tegstam.
FLIR’s 2.6 kg (5 3/4 lb) GasFindIR camera simplifies scanning for gas leaks.
GasFindIR, which scans at 25 Hz PAL, or 25 images a second, is a hand-held unit weighing 2.6kg (5 3/4 lb). It easily scans large areas for gas leaks in a short period of time.
‘Smart’ leak detection
The camera is capable of very high detection sensitivity. For example, it can detect leaks as small as 0.4 g (0.01 oz) per hour for butane and propane, and 0.6 g (0.02 oz) for ethane, as has been verified in independent laboratory tests conducted at 3 m (10 ft) distance using standard optics.
Such optical imaging using infrared cameras has lifted leak detection and repair (LDAR) to new efficiencies, for which reason it has been dubbed “smart” LDAR. The technology provides a number of benefits compared with the standard “sniffer” technology based on the use of a toxic vapor analyzer (TVA).
When sniffing for leaks, the inspector has to approach close to the point being inspected. If there is a leak of an invisible but toxic gas, the inspector can be exposed. Each point or location where a leak might occur has to be inspected individually. Given that a refinery or petrochemical plant might have between 100,000 and 1 million points, this makes inspection a massive task.
According to an estimate by the Environmental Protection Agency (EPA) in the US, an inspector using the TVA method surveys an average of 500 valves in an eight-hour shift. A team of eight inspectors might take three months to survey a medium size refinery, says Tegstam.
Moreover, many points are difficult or even impossible to access. In windy conditions it is difficult to make an accurate estimate of the size of a leak. So, the method is time-consuming, costly, and, in several respects, unsatisfactory.
The same considerations apply to the use of TVAs to inspect natural gas transmission facilities. Pilot programs in this sector have detected failed rupture disks, crankcase vent leaks, and numerous vent stack leaks, Tegstam says. Vent stack leaks are notoriously difficult to detect with TVAs due to their inaccessibility.
In contrast, GasFindIR can scan a wide area of plant containing multiple points from a single vantage position. According to Tegstam, the camera makes it possible to inspect 3,000 points an hour, making it possible for two people to survey completely a medium size refinery in two weeks.
The EPA has responded positively to the arrival of the new technology and, in conjunction with industry and researchers, has set about developing standards for a smart LDAR inspection program.
The two technologies are not mutually exclusive, Tegstam says. Many companies use them in tandem, employing GasFindIR to detect leaks and sniffer technology to evaluate them in greater detail.
The camera also can be equipped with a longer focal range lens for distance surveillance such as conducting pipeline surveys from a helicopter. A number of US gas transmission companies, including El Paso Natural Gas and Western Gas Resources, already have acquired the camera.
Several unsolicited inquiries have been received from offshore operators, among others, according to Erik Ødegård, Presisjons Teknikk’s product manager, thermography. Such users are among those targeted in Norway by FLIR’s distributor, Presisjons Teknikk, which has its own GasFindIR demonstration unit.
In addition to enhancing safety and protecting the environment, GasFindIR also can deliver an economic boost. Service companies in the natural gas transmission business have documented cases in which over $2 million in annual savings have accrued from tackling as few as five leaks detected by the camera.
GasFindIR has been certified for the detection of a wide range of gases, including benzene, ethanol, ethylbenzene, ethylene, heptane, hexane, isoprene, MEK, methane, methanol, MIBK, octane, pentane, 1-Pentane, propylene, ,toluene and xylene, as well as butane, ethane, and propane.
As a next step, the company plans to extend the technology to detecting other chemicals and gases that currently fall outside GasFindIR’s 3-5 μm waveband.
For more information, contact Johan Tegstam, FLIR Systems. Tel +46 8753 2500, fax +46 8753 2364;[email protected], www.flir.com; or Erik Ødegård, Presisjons Teknikk AS, tel +47 2340 4147, fax +47 2340 4142; [email protected].
