In wood processing, biomass power generation, and papermaking industries, level measurement in wood sawdust silos has long posed significant challenges. This seemingly simple material presents three major level measurement pitfalls:
Measurement Challenges:
1. Dust Interference: Fine wood dust creates "measurement fog" during conveying, the flying dust poses a challenge to level measurement of wood chip.
2. Varying Angle of Repose: Fluctuations between 35°-55° depending on moisture content
3. Low Dielectric Constant (ε≈1.8-2.5) causing weak signal reflection
4. Bridging Phenomena: Fiber interlocking creates cavities and false level signals
Fiber interlocking creates cavities and false level signals
Limitations of Conventional level Measurement Technologies
- Ultrasonic Level Transmitters:
Dust absorbs acoustic waves, causing >15% measurement drift
When sawdust accumulates, the gaps are relatively large, and the measurement effect of
ultrasonic level gauge is poor.
- Submersible Pressure Transmitters:
Wood fibers entangle probes causing permanent damage. submersible pressure transmitters are used to measure liquid level , such as water, diesel, fuel oil , not suitable for wood chips.
80GHz Radar Level Transmitter: Revolutionizing Wood Chip Measurement
Utilizing Frequency Modulated Continuous Wave (FMCW) technology with 78-82GHz high-frequency microwaves. The 3.6mm wavelength (one-third of conventional 26GHz radar) combined with 12° narrow beam angle enables precise focusing:
1. High-frequency microwaves penetrate dust clouds
2. Narrow beam avoids wall interference
3. Dynamic surface tracking algorithm handles irregular surfaces
4. Echo enhancement technology compensates for weak reflections
|
Parameter
|
Ultrasonic
|
26GHz Radar
|
80GHz Radar
|
|
Dust Penetration
|
≤30%
|
≤50%
|
≤85%
|
|
Beam Angle
|
12°-15°
|
20°
|
3°-12°
|
|
Min. Dielectric Constant
|
N/A
|
≥2.0
|
≥1.5
|
|
Bridging Detection
|
None
|
Limited
|
Intelligent
|
Key Technical Specifications of wood chip level transmitter:
- Frequency Range: 78-82GHz (λ=3.6mm)
-Max silo level can reach to 120m
- Accuracy: ±2mm (even in 10m~20m high silos)
- Adjustable Beam Angle: 3°/6°/12° (software-configurable)
- Process Temperature: -40~200°C (with air purge interface)
- Antenna Materials: PTFE sealed/ceramic (anti-clogging)
- Signal Processing: 64 spectra/sec + AI echo pattern recognition
- Output 4-20mA, option with HART and MODBUS RTU
- Universal flange adjustment angle, suitable for solid measurement, flange size can be 3”,4”,5”6” and 8 inches.
Gimbal flange for solid wood chip measurement
Industrial Case Study:
A biomass power plant achieved after implementing 80GHz radar:
1. Measurement stability increased from 68% to 99.2%
2. Annual maintenance savings: CNY 400,000
3. Silo utilization improved by 22%
4. Eliminated bridging-related downtime
