How is coating identified?
Internal coating within the kiln can be identified by analysing the changes in kiln shell temperature during an operating campaign. Build-up of process material on the refractory surface is referred to as coating and this provides an insulating effect in addition the that of the refractory. This causes a reduction in the kiln shell temperature.
Thermoteknix Centurion kiln shell scanning systems have the required sensitivity to detect the small variations in kiln shell temperature caused by the coating and using a proprietary algorithm the coating thickness is estimated with a high degree of repeatability.
The coating thickness data can then be displayed for the entire kiln shell interior to present the kiln team with a detailed map of coating build ups.
Understanding the internal coating conditions enable the kiln team to identify and control problematic coating rings, unstable coating, refractory degradation or damage and non-ideal process conditions.
Why is brick information shown in kiln shell scanner software?
Accurate refractory bricking information is essential for the continuous optimisation of the refractory strategy developed by the kiln team.
As campaigns run, kiln temperature and coating data is continually collected for evaluation and analysis to determine how refractory products have performed in each zone of the kiln.
The WinCem software provides easy access to the refractories changes throughout the campaign across all zones of the refractory. Refractory which has not performed well is identified and revised bricking plans can be developed and validated.
How do the Centurion kiln shell scanners compensate for atmospheric conditions?
The rotary kiln shell emits different amounts of infrared radiation across a wide spectral range, the amount of radiation emitted is a function of the temperature of the steel shell. Accurate measurement of the kiln shell using non-contact temperature measurement relies on eliminating causes of measurement error such as atmospheric absorption between the heat source and the measurement system, in this case the infra-red detector within the Thermoteknix Centurion scanner system.
The atmosphere contains gasses and vapours which are capable of absorbing infra-red radiation. This means that natural variations in atmospheric conditions will cause a variation in the absorption of some of the infrared energy emitted by the kiln shell. The energy absorbed by the atmosphere reduces the total energy that can reach the measurement system which will cause a low reading.
Over the spectrum of infra-red emission there are bands of wavelength which can easily pass through the atmosphere without suffering significant attenuation. Thermoteknix Centurion scanners have an advanced band pass filter arrangement which rejects wavelengths that are subject to random weather or pollution related attenuation and only lets a tightly defined band of stable infra-red radiation into the measurement system. This ensures that the scanner system is not subject to measurement errors and is capable of providing reliable and repeatable data.
Why is detection resolution better than measurement resolution?
Detection resolution and temperature measurement resolution are industry standards for infrared kiln shell scanners. Measurement resolution reflects the larger spot size required with confidence to detect 95% of the energy from a given point on the kiln. Detection resolution detects 50% of the energy from that same point on the kiln, sufficient to detect hot spot formation, but not enough confidence to give accurate temperature measurement.
These resolution specifications are critical when comparing performance of different scanners. The lower the resolution number (typically specified in mrad), the more sensitive the scanner is and the more likely to measure temperature of a small hot spot on the kiln shell sooner rather than later.
How do Centurion kiln shell scanners achieve measurement repeatability over time?
Long term stability is an essential characteristic of a high performance measurement system. Long term stability ensures that data has high integrity and that shell temperature data can be usefully compared over extended periods of time. Both of these are critical to the evaluation and assessment of the refractory condition in the kiln.
The Thermoteknix Centurion incorporates two advanced, micro black body cavities in its design. These reference standards are maintained by high stability Platinum Resistance Thermometers (PRT) and provide a zero and span reference point that is extremely stable over very long periods of time, and are unaffected by ambient temperatures even over the Thermoteknix Centurion scanners exceptionally wide selectable operational range of -40°C to +70°C.
The reference black bodies are both measured by the system on each scanning rotation, up to 30 times per second. Coupled with the exceptional short term stability of the cooled MCT sensor the Centurion scanner system delivers high integrity data and an extended recommended calibration interval of 24 months.