Media-agitation Pulverizer Agitator Design for Grinding Media Circulation
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Solution Overview
Problem
Conventional media-agitation type pulverizers face issues with segregation of grinding media, leading to unstable operation and excessive wear of agitating and separating members, especially at high flow rates and high viscosity concentrations.
Innovation Solution
A media-agitation type pulverizer design featuring a cylindrical grinding chamber with a rotary agitating means and a grinding media separating means, including a circular hub member, annular end plate, and grinding media scraping-out members, with a grinding media circulation opening that allows for a wide open ratio of 50-90% to prevent segregation and wear, and a screen-type separating means with a support member to facilitate smooth media flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the circulation flow rate of material slurry is increased or the material slurry has high viscosity and high concentration, then the pulverization efficiency is improved, but the grinding media are segregated in specific regions causing a rise in internal pressure and precluding stable operation
Solution Approach 1:
The grinding chamber is divided into a first region (outer peripheral portion) and a second region (central portion) by the agitating shaft. The separating device is specifically disposed in the second region to create segmented zones with different functions, allowing grinding media to be retained in the central region while enabling efficient circulation in the outer region.
Solution Approach 2:
The agitating shaft acts as an intermediary structure that both agitates the grinding media and provides a pathway for media circulation. The shaft's rotation creates centrifugal force to prevent segregation while its central cavity allows media to flow from the outer region to the inner region, mediating between the conflicting requirements of high circulation and stable operation.
2Productivity
If the circulation flow rate is increased, then the pulverization efficiency is improved, but the solid content fixedly adheres to recesses in the agitating shaft and the outer peripheries undergo uneven wear
Solution Approach 1:
The agitating shaft is designed with recesses that are strategically positioned and shaped to prevent solid content adhesion before it becomes a problem. The rotation of the shaft creates continuous motion that prevents fixed adhesion, and the recesses are designed to facilitate easy removal of any adhered material, addressing the wear issue before it significantly impacts service life.
Solution Approach 2:
The agitating shaft rotates at controlled speeds to create dynamic conditions that prevent solid content from fixedly adhering to recesses. The rotation generates centrifugal force that keeps grinding media in motion and prevents deposition, while the dynamic movement allows for uniform wear distribution rather than localized uneven wear.
3Reliability
If a separating device is disposed in the cavity formed in the end portion of the agitator shaft, then the separating device is protected from collision with grinding media, but the device complexity increases
Solution Approach 1:
The separating device is merged with the agitating shaft structure, where the shaft's central cavity and rotational motion serve dual purposes: protecting the separating device from grinding media collision while simultaneously agitating the media and enabling circulation. This integration reduces overall device complexity compared to having separate protective structures.
Solution Approach 2:
The agitating shaft performs multiple functions: it agitates the grinding media, provides structural support for the separating device, enables media circulation through its central cavity, and protects the separating device from collision. This multi-functionality eliminates the need for additional separate components, reducing device complexity while maintaining reliability.
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
The design prevents solid content adhesion and uneven wear, ensures stable operation without pressure rise, and enables large-flow-rate circulation by effectively circulating grinding media and reducing segregation and wear on the separating members.
Implementation Method 1
by an action of centrifugal force of the agitating means, a flow causing the grinding media and material slurry inside the agitating means to be led to the outside of the agitating means is formed
Data Source
AI summary
[Problem] To resolve segregation of grinding media to thereby enable a large-flow-rate circulation operation while reducing wear of an agitating member and a grinding media separating member. [Solution] In a media-agitation type pulverizer, the agitating means comprises: a circular plate-shaped hub member (26) fixed to an end of a rotary drive shaft located inside a grinding chamber, wherein the rotary drive shaft extends front the side of one end of the grinding chamber into the grinding chamber; an annular end plate (28) disposed in spaced-apart relation to the hub member in an axial direction of the rotary drive shaft; a plurality of agitating members (30) fixed between the hub member and the end plate at circumferential intervals, in a posture where each of them protrudes radially outwardly from respective outer peripheries of the hub member and the end plate; and a plurality of grinding media scraping-out members (31) each extending radially inwardly with respect to the outer peripheries of the hub member and the end plate, wherein an open region as a part of an outer periphery of the agitating means other than thicknesses of the agitating members and the grinding media scraping-out members is formed as a grinding media circulation opening (22a) for circulating the grinding media from an inside to an outside of the agitating means, and wherein an area ratio of the grinding media circulation opening to a circumferential plane between opposing surfaces of the hub member and the end plate of the agitating means is set to 50 to 90%.