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Microwave Measuring System, LB 356-456 Micro-Moist
Moisture Content in Coal is an important parameter:
Preparation-Regulate Moisture Content
Handling-Dust-Ice
Transport-Weight
Trading-Weight
Calorific Value
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Microwave Measuring System, LB 356-456 Micro-Moist
• Microwave Transmission Techniques are the most accurate method of determining moisture content of Coal
• Attenuation/Area Weight
• Phase Shift/Area Weight
• Phase Shift and or/Attenuation
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Microwave Measuring System, LB 356-456 Micro-Moist
Attenuation measurementcan provide accuracy up to 1wt% moisture
Temperature dependence error
Bulk Density dependence error
Particle size dependent error
Conductivity dependent error
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Microwave Measuring System, LB 456 Micro-Moist
Phase Shift Measurement:or (Combined Attenuation and Phase Shift)
Independent of Temperature of Coal
Independent of Particle Size variations
INTEGRAL Area Weight Compensation
Accuracy of 0.2 wt% moisture achievable
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Principle of Operation
Microwave Measuring System, LB 356-456 Micro-Moist
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Microwave Measuring System, LB 354-356-456 Micro-MoistThe choice of 2.7-3.4 GHz frequency range:
• Measurement of bulk, not surface. This provides a representative measurement
• The temperature coefficient of free water crosses zero at 3 GHz
• Attenuation due to ionic conductivity (salt content,…) is reduced at higher frequencies
• Frequency analysis over the frequency range provides phase measurement greater than 360 deg with plausibility control
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Microwave Measuring System, LB 356 Micro-Moist
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Microwave Measuring System, LB 356 Micro-Moist Coal Preparation Plant:
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Microwave Measuring System, LB 356 Micro-Moist
Coal Preparation Plant management reported precision of 0.4% moisture (one sigma RMS)
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Microwave Measuring System, LB 456 Micro-Moist
Product Improvements:
• Reference cable can be replaced by short link if To constant
• PT-100 Temperature Compensation with direct connection
• Detector to Evaluation Unit uses FSK (Frequency Shift Keying)
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