Classifier Assembly Guide Vanes for Vertical Roller Mill Airflow Control
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Solution Overview
Problem
Vertical roller mills face challenges in efficiently classifying ground material due to the impact of air currents and turbulence generated by rotors or classifier baskets, especially in larger mills with higher throughput, which affects the overall airflow and efficiency of the classifying units.
Innovation Solution
A classifier arrangement with guide vanes around each classifier, directing process air and crushed material particles to influence the angle of attack, capturing rejected particles in an open profile to guide them back to the grinding plate for regrinding, and optimizing airflow direction using guide vanes and chutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of roller mills is increased to process higher capacities, then throughput of ground material is improved, but air currents and turbulence generated by rotors negatively impact overall airflow and classifying efficiency
Solution Approach 1:
Guide vanes are introduced as intermediary elements between the process air source and the classifier rotors. These guide vanes mediate the airflow by directing it along specific paths, reducing turbulence and harmful air currents while maintaining the high throughput capacity of larger roller mills.
Solution Approach 2:
The invention changes the parameters of airflow by using guide vanes to control velocity distribution, flow direction, and turbulence intensity. This allows the system to maintain high productivity while modifying the airflow characteristics to reduce negative impacts on classifying efficiency.
2Ease of operation
If guide vanes with closed profiles are used to direct process air onto the rotor, then airflow direction is controlled, but rejected particles cannot be captured and must be scattered throughout the classifier space
Solution Approach 1:
The guide vanes are designed with open profiles that serve multiple functions: directing process air onto the rotor for efficient classifying and simultaneously capturing rejected particles. This multi-functionality eliminates the need for separate particle management systems, reducing device complexity while maintaining operational ease.
Solution Approach 2:
The open profile design converts what would normally be a harmful scattering of rejected particles throughout the classifier space into a beneficial concentration and guidance of these particles to specific areas, improving overall system efficiency and simplifying particle management.
3Productivity
If multiple classifiers are arranged in the same spatial plane to increase throughput, then classifying capacity is improved, but interference between adjacent classifiers affects performance
Solution Approach 1:
Each classifier is equipped with its own dedicated guide vane arrangement, providing localized airflow control. This local quality approach ensures that each classifier operates independently with optimized airflow patterns, preventing interference between adjacent classifiers while maintaining high overall classifying capacity.
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
Enhances the efficiency of the classification process by reducing disturbances and improving the classifying result while minimizing energy consumption, allowing for smaller, identical classifiers to be combined for higher throughput.
Implementation Method 1
directing the process air, which is used to transport the ground material crushed by the grinding rollers to the classifiers, specifically onto the rotor or classifier basket by means of guide vanes. This allows the angle of attack of the process air, and thus of the crushed material particles transported with it, to be influenced
Implementation Method 2
particles rejected by the rotor because they are not yet sufficiently sized can be captured in the open profile and then guided by gravity to the lower section of the classifier
Data Source
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AI summary
The invention relates to a classifier assembly (10) for a vertical roller mill, comprising at least two classifiers (12). Each classifier (12) has an active rotor (14) which is rotatable about an axis of rotation (16). The axis of rotation (16) is oriented at least at an angle of 50° to the vertical. The invention is characterized in that, around each classifier (12), a guide-vane assembly (30) at least partly surrounding the classifier and having at least one guide vane (32) is provided. The guide vane (32) has a profile (34) which is open toward the axis of rotation. The invention also relates to a vertical roller mill having a classifier assembly according to the invention.