Infrared imaging improves process monitoring and control

Paul Boughton
Continuous, real-time and on-line infrared imaging provides an important monitoring and control tool for a vast number of production and plant processes.

Thermal imaging technology supplied by Raytek has been crucial to the success of one customer whose business involves incinerating chemical industry waste.

To avoid any harm to the environment from chemical waste, Raytek's customer incinerates it in a rotary kiln at very high temperatures - up to 500°C.

To increase combustion efficiency, the kiln rotates at very slow speeds - typically 4 to 6 revs/h. Over time, the refractory brick protecting the kiln wall degrades and needs to be replaced. There is also the possibility that a single brick could fall, leading to a hotspot on the kiln shell and causing catastrophic failure.

Taking action too soon will negatively impact productivity, while waiting too long may put a high cost capital asset at risk.[Page Break]

Synchronising thermal imaging

The customer opted to install a Raytek CS210 system which is able to synchronise thermal imaging at speeds as low as 2 revs/h. In addition, as these kilns are typically quite short (10-15 m), the CS210 is specifically designed to detect each potential refractory loss across the shell lengths by providing a gapless sampling of pixels. The system helps process optimisation by detecting abnormal operating conditions such as faulty flame position, and reduces downtime by providing data to plan refractory replacement and avoid unscheduled maintenance.

As the operational life of the refractory is extended, each extra month on top of the original yearly maintenance saves the company EUR38,000.[Page Break]

Inspecting electrical equipment

Meanwhile Raytek parent company Fluke has launched five new IR cameras that are designed to be powerful yet easy to use. Of most interest to process engineers are the Ti110 and T1125 models (Fig. 1). These are aimed at process engineers who need to troubleshoot, maintain and inspect electrical and mechanical equipment and components.

Included among the cameras' capabilities are: IR Optiflex focus system for fast, easy to take, sharply focused, accurate images; IR-Fusion technology blends digital and IR images into a single image to precisely document problem areas; lightweight, designed for one-handed operation; rugged construction; multi-mode video recording to monitor processes over time and troubleshoot frame-by-frame; IR PhotoNotes annotation system to keep an exact record of equipment models, nameplates; and electronic compass, which saves precise location with the image.

Fluke has also announced a major expansion of its US service options with Fluke CarePlans, a series of extended warranty and calibration packages featuring priority service to ensure a new level of convenience for users of Fluke handheld instrumentation.

The gold and silver CarePlan packages offer comprehensive priority service and support, including extended factory calibration, extended warranties, and expedited shipping for 170 different Fluke tools.

With CarePlans, users can - for the first time - obtain Fluke calibration services and repairs directly from their regular distributor, making it easy to get best-in-class Fluke service.

"These CarePlans are about convenience and quality," said Clare Grehofsky, director of Fluke Service. "Our new CarePlan packages provide greater convenience and value, along with peace of mind for Fluke handheld test tool users."[Page Break]

Why thermal imaging?

Omega recommends that potential users ask themselves some important questions when considering thermal imaging technology. For example, why use a thermal imager in the first place?

According to the company, thermal imagers allow users to measure temperature in applications where conventional sensors cannot be employed.

Specifically, in cases dealing with moving objects, or a conveyor belt, or where non-contact measurements are required because of contamination or hazardous reasons such as high voltage, where distances are too great, or where the temperatures to be measured are too high for thermocouples or other contact sensors.

The thermal imagers provide an image which shows the temperature difference of the object being measured. Hot spots can be seen immediately versus traditional infrared guns which average the area being measured.[Page Break]


Another question that must be asked concerns the importance of resolution. Essentially, a higher resolution camera means that smaller problems can be found at greater distances - an important consideration on a large and complex process plant.

Then there is the application to be measured.

Here a number of important factors must be taken into consideration, including field of view (target size and distance), type of surface being measured (emissivity considerations), spectral response (for atmospheric effects or transmission through surfaces), temperature range and mounting (handheld portable or fixed mount). Other considerations include response time, environment, mounting limitations, viewing port or window applications, and desired signal processing.[Page Break]

Thermopile array detector

One solution recommended by Omega is its compact OSXL-101 IR thermal imaging sensor utilising a thermopile array detector.

The sensor measures real time temperature and a thermal image up to 300°C. Ethernet connectivity allows the sensor to communicate with the PC running the application software or customers' LAN.

In monitoring mode the temperature data is outputted continuously by a command from the PC. In capturing mode the temperature data is outputted row-by-row horizontally by a command from, for example, a PLC.

Up to four sensors are able to connect to a PC via LAN and viewer software allows users to monitor thermal images, measuring temperature and alarms.

Meanwhile Arc imagers from Land Instruments are a range of general purpose thermal imaging cameras which are rugged enough to withstand heavy industrial applications, while compact enough for use in R&D and automation. Arc is a high resolution radiometric thermal imager providing detailed thermal images with what the company describes as unsurpassed temperature accuracy.

Arc is available with two temperature ranges (-20- 500°C and 100-1000°C), four lenses, two frame rates and three software variants to meet exact user requirements.[Page Break]

Data processing

Sophisticated data-processing is performed within the Arc camera. Connection to an I/O module is made via standard industrial Ethernet, offering stand-alone operation for a smarter image. Arc is supplied as standard with Arc Viewer software, which enables visualisation of the thermal data, while Viewer+ offers configuration of the Smart Camera features and LIPS allows full analysis, recording and playback of thermal data.

The range of four lenses enables viewing of any target, at any distance with outstanding image clarity. Coupled with this is the wide ambient temperature operating range making Arc suitable for everything from bench top monitoring to the most demanding industrial applications. Arc also uses remote motorised focus allowing quicker installation and safer and convenient operation.[Page Break]

Ladle refractory

In addition, the company's new Vessel Manager monitors ladle refractory condition for greater safety and control in molten metal operations.

Designed for steel mills, copper smelters and other molten metal processes, the system includes multiple thermal imaging cameras positioned to view the entire exterior surface of a molten metal ladle.

The use of refractory lined vessels (ladles) to transport molten iron and steel is commonplace in steel plants world-wide. Over time, the refractory condition degrades until it must be re-lined.

Traditionally, the timing of these re-lines has been based on previous experience and best practise information from the plant's Refractory Manager. However, this mechanism can be unreliable and break-outs have occurred, causing severe damage to plant, personnel injuries and lost revenue due to production delays.

Temperature information is collected each time the ladle passes a measurement station, allowing assessment of the extent and distribution of wear to the lining. The system's software creates actionable records for each ladle.[Page Break]

Preventing problems

In particular, Vessel Manager data helps prevent two serious problems: accurate statistical measurement of lining wear allows managers to set realistic relining schedules, reducing both the cost of too-frequent maintenance and the risk of break-outs; constant measurement of temperature changes helps identify ladles that are threatening to fail earlier than predicted, sounding an alarm and lessening risk of plant damage and worker injury.

By identifying the exact location of unexpected hot spots in a particular ladle, the system allows some partial re-linings to extend the life of the ladle.[Page Break]

High-resolution infrared OEM modules

Infrared (IR) specialist Xenics has launched new high-resolution IR OEM modules and outdoor camera systems.

XenicsCores is a new family of high-resolution IR OEM modules offering easy integration and excellent image quality. The first two members are the Xenics Short Wave module XSW-640 and the Xenics Thermal Module XTM-640. These compact uncooled OEM modules are lightweight, low-power consuming and easy to integrate in a customer's application via the universal QTE connector. Longer detection, recognition and identification distances are possible thanks to the small size of the pixels of the detector.

The SWIR module XSW-640 is based on an uncooled InGaAs array of 640 by 512 pixels with 20 µm pixel pitch and measures only 45 x 45 x 24mm. It is optimised for the detection of shortwave infrared radiation between 0.9 and 1.7µm wavelength which can be extended into the visible spectrum down to 0.6 µm. With a sensitivity of less than 90 noise electrons, the XSW is optimised for active and passive night vision.

The LWIR module XTM-640 is based on an uncooled microbolometer array of 640 by 480 pixels with 17 µm pixel pitch and measures only 45 x 45 x 32 mm. It is optimised for the detection of thermal IR radiation between 8 and 14 µm wavelength and achieves a high thermal sensitivity of 50 mK. Such small size, weight and power (SWaP) are essential for portable applications.

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