Vertical Mill Roller Stability Control via Bed Height Feedback
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Solution Overview
Problem
The existing methods for controlling vertical mills in the concrete and coal power industries face complexity due to indirect and nonlinear relationships between control variables such as grinding pressure, air flow, and particle fineness, making it difficult to maintain optimal grinding bed stability and efficiency.
Innovation Solution
A method that continuously measures the mechanical condition of the roller and grinding bed stability, using motion equations to calculate stability and adjust control variables like grinding pressure and product flow to maintain a predefined nominal condition, facilitating direct adaptation of control variables and monitoring for potential malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If control variables (grinding pressure, air flow, sifter speed) are adjusted to maintain nominal grinding bed conditions, then grinding bed stability is improved, but the control system complexity increases due to indirect and nonlinear relationships between variables
Solution Approach 1:
The patent implements a feedback control system where measured parameters (grinding bed elevation, particle fineness, particle volume) are continuously monitored and compared against nominal values. The control variables are automatically adjusted based on deviations from nominal conditions, creating a closed-loop system that maintains grinding bed stability despite the nonlinear relationships between variables.
Solution Approach 2:
The patent changes the control approach by introducing a new parameter - the stability parameter derived from mechanical condition monitoring of the roller. This parameter provides a more direct indication of grinding bed stability, allowing for simpler control adjustments compared to trying to directly control the indirect and nonlinear relationships between traditional control variables.
2Productivity
If multiple control variables are continuously adjusted to maintain nominal grinding conditions, then grinding efficiency is improved, but the risk of control errors and malfunctions increases
Solution Approach 1:
The feedback mechanism continuously monitors the stability parameter and adjusts control variables only when deviations from nominal conditions are detected. This reduces the risk of erroneous adjustments while maintaining grinding efficiency, as the system responds only to actual deviations rather than continuously adjusting all variables.
Solution Approach 2:
The control system is designed to automatically detect and correct deviations from nominal conditions without external intervention. The system monitors its own performance through the stability parameter and self-adjusts control variables, reducing the complexity of manual control and minimizing human error while maintaining high grinding efficiency.
3Measurement precision
If direct measurement of grinding bed stability is implemented, then control precision is improved, but measurement and detection difficulty increases due to the indirect nature of stability parameters
Solution Approach 1:
The patent uses the mechanical condition of the roller as an intermediary parameter to indirectly measure grinding bed stability. Instead of attempting to directly measure the complex stability of the grinding bed, the system monitors the roller's mechanical condition (vibrations, forces) which serves as a proxy indicator, simplifying the measurement process while maintaining precision.
Solution Approach 2:
The patent replaces direct mechanical measurement of grinding bed stability with indirect measurement through roller mechanical condition monitoring. By substituting direct stability measurement with roller condition monitoring, the system achieves precise stability assessment through easier-to-measure mechanical parameters of the roller.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for more precise and automatic control of the grinding process, improving the stability and efficiency of the grinding bed, reducing the risk of mill instability and enabling real-time adaptation of control variables for optimal operation.
Implementation Method 1
at least one roller (7) which rolls on the grinding body (3) under a grinding pressure (Fn)
Implementation Method 2
a grinding bed height (x) of the grinding bed (9) between the grinding body (3) and the roller (7) is continuously measured
Implementation Method 3
the stability of the grinding bed (9) is continuously determined from the mechanical condition of the roller (7)
Data Source
AI summary
A method for grinding a grinding material in a mill including a grinding body and at least one roller which rolls on the grinding body under a grinding pressure, wherein the grinding material is fed in a stream of grinding material, forms a grinding bed between the grinding body and the roller and is crushed in the grinding bed by the roller, wherein a grinding bed height of the grinding bed between the grinding body and the roller is continuously measured, and wherein the mill is controlled based on control variables to achieve a predetermined nominal condition, wherein the control variables include at least the grinding pressure and the stream of the grinding material and the nominal condition includes at least one nominal value for the grinding bed height, wherein a mechanical condition of the roller and therefrom a stability of the grinding bed are continuously determined.