PROCESS CONTROL:
Measuring Temperature with Infrared Technology
Utilizing imaging radiometers to control process and monitor quality and safety of plant equipment is a reality now more than ever. As with any technology cost is a driving factor as well as return on investment. This paper will discuss a brief history and one specific system and briefly describe several others. Using imaging radiometers for process control is not new to the commercial and industrial community. The advent of microbolometer technology has revolutionized the infrared camera business.
1. Why this technology will continue to grow
Non-contact temperature measurement is the future. It impacts our lives every day of the week and most of the time we just do not realize it. From INFRARED motion sensors at traffic lights to the infrared motion sensors on our bedroom lighting, airport toilets, automated doors at the local grocery store or the faucets that turn on and off without a touch, infrared sensors impact our lives every day in a very helpful way!
Fact…Temperature is the number one form of measurement used in any process control application. As we get better at non-contact measurement and customers gain confidence, the technology will expand. Pressure and flow are also critical measurements as well, but temperature is far and away number one.
Infrared mechanical scanning technology has been around for years. Line scanner’s and line cameras utilizing this technology have been used for years in small numbers for specific process control applications, rotary kilns, steel and glass production. Two color point radiometers are in use in practically every steel mill in the world although there are a few small corporations who have still not embraced non-contact infrared technology. Based on my studies those hold outs have had some previous bad experience, due primarily to a lack of knowledge of the sales person introducing them to the technological capability of the systems, i.e.: emittance, wavelength, etc. Point radiometers are prolific in every industry. Competition has increased and driven the price down further than ever in the history of the business. This is happening with imaging radiometers now and will continue for years to come.
2. Let’s begin with a little recent history
1990 – Honeywell Research develops the microbolometer.
Mid 1990’s Rockwell, Boeing and Lockheed build the 1st microbolometer based imaging systems for military applications. In August of 1997, after 4 to 5 years of development Agema Infrared introduces the 1st hand held imaging radiometer. This 570 system sold for $49,950.00 and a software package was $6995.00, bringing the total average sale price of a system to almost $57,000.00 USD. I know this because I was one of the guys in the field selling these systems. In mid 1998 the Thermovision fixed camera system is developed and costs around $40,000.00 and is sold with software for about $47,000.00. It took Agema about six months to get the 570 handheld systems solid and stable, just as many new products today. The first hand held imagers were much noisier in terms of image quality and definitely in comparison with their PTSI, stirling cooled predecessors. Agema was 1st to build a radiometric system although Inframetrics was not far behind. Insight by FLIR managers at the time was seminal. The merger of FLIR, Agema, and Inframetrics helped put them where they are today. Agema was a wholly owned subsidiary of Spectra Physics. In a trade for 46% of FLIR ownership Agema was merged with FLIR. You see FLIR had not even begun development of the microbolometer technology and today they own approximately 75% of the world commercial market. These same systems are available today for under $20,000.00 and some smaller resolution systems for under $10,000.00.
3. Business fundamentals
Our company has successfully installed hundreds of cameras for fixed mounted process control applications. Many individuals selling systems do not want to push this technology because of lack of knowledge, but the primary reason is the short term financial gain. You see, selling a hand held system typically has a one day to one year sales cycle. A process job typically averages an eighteen month to thirty month sales cycle.
The other issue is the guy interested in the process control system is not the predictive maintenance manager, reliability manager, home inspector or the facilities manager. These are the guys typically visited during a hand held sales demonstration.
4. Infrared Camera System: General Description
Camera systems can be multiple or stand alone. A system can sound an alarm, ring a bell, or totally control a system. The system configurations differ based on the object wavelength, temperature, or if the object is moving or static. How many pixels do you need? Is image quality critical? What is the minimum spot size you need to measure. Each cameras 320 x 240 pixel array gives non-contact temperature measurement at 76,800 points for each camera. Real time images are transmitted from each camera by an Ethernet board located in each camera. The data is transmitted from each camera by a wireless antennae located on the unit structure and are received by an antennae located on top of the control room. A Cat 5 cable feeds the data to a single PC running real time alarming software. This wireless system reduced the over all system cost by eliminating the need to install conduit and pull wire.
We have also installed numerous systems using twisted pair and fiber optics to transfer data.
The software allows each camera to monitor numerous locations simultaneously and even integrate these systems into the unit total control PLC. The system can show multiple camera feeds on a single or multiple monitors. Screen choices allow display of data in multiple formats and on user selectable screens. If you want to view camera # 4 simply select camera # 4.
Multiple color scales from white hot to dark cold are available. Viewing temperature over time, histograms, 3-D displays of each image are available at the touch of a finger. Temperature ranges can change automatically and be exported to Excel. Multiple lens options are available as well as enclosure options to fit your environment.
Monitoring of these vessels is a safety and process control issue. Outdoor temperatures on the structure can exceed 120 F and we have some systems installed in environments where temperatures reach -40 F.
Process control utilizing single or multiple cameras has evolved into a mature process and the cost of these systems has come down dramatically. The systems can be easily interfaced into plant SCADA systems and installation is quite easy. To date we have not had to replace even one operating camera and we have systems that have been running continuously for almost 7 years in some locations.
Applications:
- Steel Mills
- Glass Manufacturing
- Plastics Manufacturing
- Plywood Manufacturing
- Baked Goods (Cookies)
- Potato Chips
- Candies
- Cooked Meats
- Small Aircraft Imaging through fog
- Astronomy
- Spectroscopy
- Airport Security
- Border Security
- Asphalt (Highway construction)
- Oil Slicks
- Gas Imaging
- Injection Molding
- Marine vision systems
- Automobile Vision Systems
- Tank Level Systems
- Weather Imaging
- Medical Imaging
- Aircraft Imaging
- Bridge Structure Imaging
- Welding Process Imaging
- Crop Imaging
These are just a few applications but they are all real applications for which thermal imaging cameras are being used today. Below I have described one high temperature application and briefly mention several others. Everything on the planet emits infrared radiation so imaging anything is possible.
One such application is measuring simulated reentry temperatures of the Space shuttle tiles at NASA Johnson’s Space centers Arc Jet vacuum chamber. We are measuring calibrated temperatures up to 3000 C. We are currently designing a system to measure to 6000 C calibrated and 10,000 C uncalibrated. An electron beam is fired into the large vacuum chamber where a mock up of the space shuttle nose and wing leading edge are sitting. Natural gas is introduced in volume through a large stainless steel tube and the electron beam ignites the gas causing it to accelerate. The velocity reaches approximately 23,000 MPH, simulating earth reentry speed.
We are also measuring temperatures of McDonald hamburger patties as they are cooked by the thousands in large process ovens in Oklahoma, Goodyear tires are measured during high speed and endurance testing applications, Glass windshields are being tested as well as wire continuity in rear windshields (for defroster quality control), Starburst candies (to insure the wrappers do not adhere to tightly to the candy), Folgers coffee (no one likes drinking burned coffee), Snickers and Milky Way bars (at Mar’s candy are measured prior to packaging). We are thermally testing the quality of 2.6 million bottles twelve ounce Budweiser beer bottles per day, looking for glass globs and bird swings that might be swallowed by you or a friend while you’re out on a Saturday night.
In Conclusion
New applications will emerge. Safety and quality control will increase dramatically due to this emerging technology. Thermal imagers and imaging radiometers are here to stay and as costs continue to come down they will become not only more prolific, but an industry standard. The primary cameras Infrared Camera’s Inc. sells for process imaging applications are the ICI 7384, ICI 7320, and the ICI 7640.
For more information about Process Control Thermal Imaging Applications please choose an article below:
Incredible Thermography Applications in Condition Monitoring
|