The AshScan DUO Low Energy Transmission (LET) analyser combines state-of-the-art nuclear and microwave technology with ground-breaking modelling and powerful statistical analysis. Installed on a conveyor belt, the AshScan delivers accurate, minute-by-minute data on percentage ash and moisture content present in the coal feed to the kiln. Combining the LET technology with microwave technology enable to measurement of both the ash content and moisture content in critical process streams to control drying process, improve the calcining and ultimately kiln efficiency in the production of clinker.
AshScan DUO Application in the Cement Industry
Coal is still the primary fuel used to deliver the energy required in the kiln firing process. The control of the fuel quality is an challenge for operations were reliance is placed on the data from suppliers to optimize the kiln firing process. The AshScan can provide critical ash and moisture analysis in real time to enable operators to make pro-active decisions on control parameters such as secondary fuel addition, burning zone temperature, drying and calcining, kiln speed and fuel rate to name but a few. The real time data on primary fuel quality enable operators to vary the kiln speed, fuel rate and the induced fan speed in any combination to maintain a proper burning zone temperature and constant kiln back-end temperature for any given input feed rate. AshScan provide specific benefits such as: Protection of equipment and personnel, stable kiln operation, maximum production rate coupled with maximum fuel efficiency and production of a consistent quality clinker.
AshScan DUO operating principle.
The AshScan utilises two radioactive sources. The technology is referred to as Dual Energy Transmission (DET) or Low Energy Transmission (LET). The addition of a low frequency microwave signal enable the measurement of moisture content in the coal.
LET analysers uses a Am-241 source which transmits “soft X-rays” at 60keV, which measures the density/atomic number of the ash forming elements within the coal. The higher the Ash content, the less 60keV rays will reach the detector. The second source Cs-137 transmits higher energy gamma rays at 660keV, which measures the bulk density of the coal and compensates for the bulk density and bed depth variations. If the Fe and Ca varies significantly within the coal, it will affect the accuracy of this analyser and introduce a shift in the calibration. E.g. wash plant receiving coal from 2 or 3 different mines with different Fe & Ca content. The analyser can store up to 16 different calibrations for different coal types, but it needs an input to know which coal is being feed at any given time, e.g. Coal from Mine A or B, etc. Accuracy is approx. 0.9 -1%
The AshScan has proprietary counting electronics, which is the fastest available on the market. The measurement and output has the fastest update time of less than 25 seconds.