Grinding Unit Mass Monitoring via Mill Shell Vibration Analysis
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Solution Overview
Problem
Current methods for measuring mass changes inside grinding units, such as ball mills, are unreliable due to interference from noise and vibrations, and direct measurement is hindered by dust and convection-based material transport, leading to inaccurate energy consumption optimization in industrial processes like cement production.
Innovation Solution
A method involving a storing unit and measuring devices to determine mass flows and changes within the grinding unit using established mass balances and state estimation techniques like Kalman filters, allowing for accurate observation and control of mass changes, even in complex processes with undetermined models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microphones are used to detect noise and vibration of the mill shell, then mass changes inside the grinding unit can be observed, but measurement accuracy deteriorates due to air gaps and interference from neighboring noise sources
Solution Approach 1:
The patent introduces accelerometers as intermediary sensors that measure vibrations directly on the mill shell, converting mechanical vibrations into electrical signals that can be processed to determine mass changes, thereby avoiding the air gap problem of microphones
Solution Approach 2:
The patent replaces the acoustic measurement system (microphones detecting sound waves through air) with a direct mechanical measurement system (accelerometers detecting vibrations on the mill shell), eliminating the harmful air gap and improving measurement reliability
2Reliability
If microphones are attached directly to the mill shell wall, then measurement reliability improves, but measurement accuracy deteriorates due to unpredictable influence on different frequencies
Solution Approach 1:
The patent employs dynamic signal processing techniques including Fast Fourier Transform (FFT) to analyze the frequency spectrum of vibrations in real-time, allowing the system to adapt to changing operating conditions and identify the specific frequency signature corresponding to mass changes
Solution Approach 2:
The patent utilizes the mechanical vibrations of the mill shell itself as the measurement medium, analyzing the characteristic vibration patterns and frequency spectra that change with mass variations, thereby achieving accurate measurements while maintaining reliability
3Loss of energy
If grinding optimization systems are implemented to monitor mass changes, then energy consumption can be optimized, but measurement accuracy deteriorates due to dust and convection-based material transport
Solution Approach 1:
The patent uses the mill shell as an intermediary structure that transmits vibration information from the grinding media and material to the accelerometers, allowing indirect measurement of mass changes without direct exposure to the harsh internal environment
Solution Approach 2:
The patent replaces direct internal measurement methods with external vibration-based measurement, substituting the need to physically access the grinding chamber with a non-intrusive method that measures through the mill shell, thereby avoiding dust and convection interference
Data Source
AI summary
A system and method are disclosed for observing a change of mass inside a grinding unit as a part of a grinding process with a storing unit. The change of mass is derived from a mass balance for the grinding unit and a mass balance for the storing unit.