Ed Kochanek
Infrared Training Center
FLIR Systems, Inc.
25 Esquire RoadNorth Billerica, MA 01862
978-901-8000 www.flir.com/thermography/americas/us/
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Abstract
Faulty equipment and poor maintenance practices often lead to excessive gas emissions that can result in lost revenue, environmental damage, regulatory fines, and compromised plant and public safety. Finding unknown leak sites allows for better preventive maintenance planning and repair, thus reducing overall tank emissions. This paper will discuss the latest infrared imaging technology which utilizes a special infrared detector and cold filter to help quickly visualize invisible gas leaks in real-time. We will also discuss how optical imaging can be used to aid in the detection and reduction of hydrocarbon gas emissions from storage tanks.
1-Pentene, 5.6g/hr | MEK, 3.5g/hr | SF6, 0.026g/hr |
Benzene, 3.5g/hr | Methane, 0.8g/hr | Toluene, 3.8g/hr |
Butane, 0.4g/hr | Methanol, 3.8g/hr | Xylene, 1.9g/hr |
Ethane, 0.6g/hr | MIBK, 2.1G/HR | |
Ethanol, 0.7g/hr | Octane, 1.2g/hr | |
Ethylene, 4.4g/hr | Pentane, 3.0g/hr | |
Heptane, 1.8g/hr | Propane, 0.4g/hr | |
Isoprene, 8.1g/hr | Propylene, 2/9g/hr | |
Other gases that can be detected (leakage rates to be determined) |
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Acetic Acid (C2H4O2) | Anhydrous Ammonia (NH3) | Butadiene (C4H6) |
Carbon Monoxide (CO) | Chlorine Dioxide (ClO2) | Dichlorodifluoromethane (FREON-12: CCl2F2) |
Ethyl Cyanoacrylate (Superglue: C6H7NO2) |
Many other gases that exhibit absorption at IR wavelengths can also be detected. |
IR Usage Considerations
Up to this point, the focus of this paper has been on storage tanks and components in petrochemical plants. However, IR imaging technology can be applied to a large number of other applications. A few of these are pictured in Figure 5. The flare stack dump valve application (upper left in Figure 5) deserves additional comments.
Flare stacks are one way of reducing the amount of VOC emissions into the atmosphere. The EPA requires continuous monitoring of the stack to ensure that combustion has taken place to prevent unburned hydrocarbon emissions. As mentioned earlier, optical imaging is one way of monitoring the stack flame. Visible light cameras can work is some applications, but in others, the gas being burned renders the flame invisible. Furthermore, visible light cameras cannot see unburned gases that are exiting the stack. FLIR developed its GF Series cameras to detect both burning and unburned gases. When a stack flame is present, it shows up in the camera image as a higher temperature against a background of sky or clouds. There will also be an apparent temperature difference between unburned gases and the background. In either https://irinfo.org/articleofmonth/images/, the camera can output its data and images to a control room via USB communications and/or HDMI in the https://irinfo.org/articleofmonth/images/ of video images.
Figure 5. A few of the many applications served by IR cameras designed for gas detection.
Still, it’s important to recognize the necessary conditions that will allow IR imaging to detect fugitive gases. The primary conditions and qualifications for successful detection of gas leakage with an IR camera are listed in Table 2. These conditions are far from being restrictive. Like any other precision instrument, an IR camera must be used properly to take advantage of its full capabilities. It is often used as the first line of defense against fugitive emissions, and in conjunction with TVAs and/or hi-flow samplers to quantify the magnitude of a leak.
Table 2. Conditions and Qualifications for Successful Leak Detection with an IR Camera
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Advantages and Benefits of IR Imaging
There are several advantages in the use of IR imaging technology for gas leak detection. IR cameras are lightweight, highly portable, robust instruments. For example, construction of the FLIR GF Series cameras is based on a design that is used in military field operations. Camera setup and use involves simple pushbutton operation. The FPA and filter used in a camera can detect a broad spectrum of gases. The camera displays real-time video images that make gas leaks more obvious. Individual video frames can be extracted as stills for use in reports.
In addition, there are several practical advantages to IR imaging in maintenance operations. An IR camera can be used to scan a large area of plant real estate as a first step in gas leak detection. This greatly shortens the process of finding individual leaks compared to the use of sniffers. IR scans are also much safer in that they minimize the use of ladders and exposure of maintenance personnel to toxic gases. Nevertheless, they can easily trace a leak directly to its source, providing a visual confirmation of exactly where it originates. Moreover, that visual image is stored in camera memory (i.e., built-in video recorder), creating a record of the leak and its subsequent repair. Some of these cameras also have an embedded GPS capability, which helps maintenance crews locate the component that needs repair.
These advantages lead to a number of economic benefits for companies adopting IR imaging technology. First and foremost, it finds more leaks and finds them quicker to reduce product loss and the risk of fires and explosions. Similarly, it reduces the chance of getting an EPA citation for emitting VOC’s into the atmosphere. Because it’s safer than many other leak detection technologies, the risk of OSHA citations is also reduced. When IR scans are incorporated into a predictive/preventative maintenance program, they make maintenance personnel more productive and lower costs. Reporting software and formal training in IR imaging technology can further increase its cost effectiveness.
About the Author
Ed Kochanek is Director of Sales for the Eastern Region of the U.S. for FLIR Systems, Inc., North Billerica, Massachusetts. His education includes a BS Degree in Commerce and Engineering from Drexel University, and he has over 10 years of experience in IR imaging technology.