Conical Grinding Roll Retrofit for Vertical Spindle Pulverizer Reliability
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Solution Overview
Problem
Existing bowl mill pulverizers face reliability issues with journal bearing longevity and require costly, time-consuming upgrades to increase coal throughput, which often result in safety concerns and inefficient grinding due to the limitations of toroidal grinding rolls and journal assemblies.
Innovation Solution
The retrofitting of a vertical spindle pulverizer with a conical grinding roll and inclined bull ring segments, along with a journal assembly featuring improved pivot shafts, stop bolts, and a bearing arrangement, allows for increased capacity and reliability by enhancing attrition grinding and reducing maintenance complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing toroidal grinding rolls and journal assemblies are used, then the pulverizer can operate with simple structure, but the journal bearing reliability deteriorates over extended periods and capacity is limited
Solution Approach 1:
The patent changes the geometric parameters of the grinding roll from toroidal to conical shape, and modifies the journal assembly structure with improved pivot shafts and bearing arrangements. These parameter changes enable better load distribution and reduced friction, thereby improving journal bearing reliability while maintaining operational simplicity
Solution Approach 2:
The patent transitions from toroidal (doubly curved) grinding rolls to conical (singly curved) grinding rolls. This curvature change simplifies the journal assembly structure while improving contact characteristics and reducing stress concentrations, leading to enhanced bearing reliability
2Productivity
If the size of grinding rollers is increased to increase coal throughput capacity, then capacity is improved, but complete removal and replacement of existing machinery is required which is time consuming and expensive
Solution Approach 1:
Instead of replacing entire grinding rollers, the patent applies local modifications to the journal assembly components (pivot shafts, bearings, locking mechanisms). These localized improvements enable capacity enhancement through optimized grinding mechanics rather than simply increasing roller size, avoiding complete machinery replacement
Solution Approach 2:
The patent divides the journal assembly into separable components (pivot shaft, bearings, locking mechanism) that can be independently upgraded. This segmentation allows for incremental improvements to capacity without requiring complete removal and replacement of the entire grinding system
3Ease of manufacture
If conventional journal assemblies are used, then the pulverizer structure remains simple, but maintenance complexity increases over extended periods due to reliability issues
Solution Approach 1:
The patent introduces adjustable and replaceable components in the journal assembly, including modular bearings and locking mechanisms. These dynamic features allow for easy maintenance and repair operations without compromising the overall structural simplicity of the pulverizer
Solution Approach 2:
The patent extracts critical maintenance-prone components (bearings, pivot shafts, locking mechanisms) as separate replaceable parts. This extraction allows for targeted maintenance and repair of only the necessary components, reducing overall maintenance complexity while preserving structural simplicity
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 solution achieves a 20-40% capacity improvement with reduced maintenance costs and enhanced safety by optimizing the grinding zone, improving the reliability of the journal assembly and pulverizer, and addressing issues like grinding roll skidding and particle distribution.
Implementation Method 1
The inclined bull ring segments are configured to register with a grinding surface of the conical grinding roll
Implementation Method 2
a journal assembly featuring improved pivot shafts, stop bolts, and a bearing arrangement
Implementation Method 3
a journal assembly featuring improved pivot shafts, stop bolts, and a bearing arrangement
Data Source
AI summary
A method of upgrading a vertical spindle pulverizer includes the steps of removing a cover from a journal opening in a housing of the pulverizer to access a grinding zone of the pulverizer, removing a first journal assembly having a toroidal grinding roll from the pulverizer through the journal opening, removing a plurality of toroidal table segments from a grinding table of the pulverizer, installing a plurality of inclined bull ring segments on the grinding table, installing a second journal assembly having a conical grinding roll in the pulverizer, and replacing the cover over the journal opening. The inclined bull ring segments are configured to register with a grinding surface of the conical grinding roll.