Online Measurement System
Online measurement system
An innovative temperature measurement technique which:
- is a non-intrusive optical method
- has an accuracy of 0.5%
- has precision of +/- 5°C
- is suitable for moving targets
- has a large stand-off distance
- robust coating application
- is a mobile system
- can remotely observe
- can be tailored for low and high temperature regimes (400° Celsius to 1550° Celsius)
What can be measured?
The proposed sensor coating system is capable of measuring temperatures on-line with accuracies of less than 5°C in different temperature ranges. The temperature measurement capability in a realistic environment was recently demonstrated on static and rotating components with material temperatures of up to 800°C and a precision of +/- 5°C. The accuracy around 650°C is estimated to be less than 0.5% with data acquisition times of currently ca 1s. These measurements have been carried out at a distance of 400mm. STS believes that, in the same conditions, a maximum distance of 2 meters between the probe and the measured target can be achieved taking the probe out of the hot area and thus minimising the need for extra cooling.
How does it work?
The Sensor Coating works by adding small amounts of dopants into standard Thermal Barrier Coatings (TBCs) commonly used on hot section components. When illuminated with (UV) light, the Sensor Coating phosphoresces, providing information about temperature, erosion and phase changes of the coating (also see Technology Fundamentals). Measurements can be carried out on static or moving components. It is a “smart” multi-functional material with a built-in sensor that can be used in jet engines and power generation turbines with possible applications in other areas. The luminescence is collected by a purpose built unique optic system which delivers the temperature reading in a digital format throughout a microprocessor. The detection system is remotely controlled through an Ethernet link which enables the operator to be located away from the system.
The coating can be applied as a thick thermal barrier coating (>100 µm), but also as a ‘sensing only’ coating which would be a much thinner coating (ca. 15 to 25µm) than a standard thermal barrier coating
When the technology meets the needs...
Today, pyrometry is the only available technique for precise temperature measurement. However, pyrometry comes with great uncertainties when operated in harsh environments, e.g. changing emissivity, stray light from other sources and fouling of optics & surfaces. The STS online measurement system demonstrated precision (+/- 5°C) comparable to commercial pyrometers but has shown higher accuracy (0.5%). By combining the accuracy and the precision, STS’s technology is the ideal technique when temperature becomes a critical parameter of an application. STS’s technique merges the advances observed in the development of today’s high temperature protective coatings with advanced acquisition systems. The observation of the luminescence life time decay is processed through a customised fitting algorithm to give the best accuracy and precision without being disturbed by black body radiation or other stray light.
Tested in a real environment – the Rolls-Royce VIPER 201 test vehicle
Southside Thermal Sciences successfully conducted a gas turbine engine test on a Rolls-Royce VIPER 201 using its fully patented sensor coating technology to measure temperatures online. The work was conducted under the project ‘SeCSy - Sensor Coating System’ which was co-financed through the Technology Strategy Board (TSB) and was in cooperation with RWE npower, LAND Instruments and Cranfield University. The VIPER gas turbine is owned by STS and has been specifically modified to enable optical access. Temperature measurements were carried out on nozzle guide vanes, in the combustion chamber and on rotor blades rotating up to 13,500 rotations per minute.
The gas stream temperature was measured, uncorrected for radiation and air flow, ca 45mm in front of the NGV and shows a very noisy signal. Temperatures in the gas stream are expected to be higher than the temperatures in the component
(featured in Modern Power Systems, Dec 2010)
STS was able to demonstrate the application of its system on a high speed rotating turbine blade at 13500 rotations per minute. Once the laser has excited the coating the phosphorescence spot on the turbine blade travels with ca 350 meters per second (a full circuit on an Olympic running track is 400m in distance. Hence, the turbine blade would take only a little longer than 1 second to go from start to finish!). The figure below shows the undistorted life time decay of the phosphorescence at that speed bridging the distance of 50mm in less than 140 microseconds. The signal is observed from a safe distance of 400mm using the STS OPETS probe. The temperature is above 400°C for this application.
Stand-off distance of the optic 400mm on this occasion, enabling real remote measurements.
For the detection of temperatures on moving parts the life time decay of the phosphor can be customised depending on speed and expected temperature range.
Where else can the online temperature system be used?
Nuclear power applications, automotive, metal or chemical processing facilities and many other fields have similar requirements for temperature detection in harsh environments. STS’s system is suitable for precise and accurate temperature measurements where traditional methods can fail. STS’s system is applicable for static or moving targets and using the OPETS probe, surface scans can also be performed.
For more information about your specific application do not hesitate to contact us.
