Vertical Roller Mill Flow-Constricting Rings for Woody Biomass Grinding
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Solution Overview
Problem
Existing vertical roller mills face issues with ungrinded materials passing through the flow-constricting flow path at a predetermined flow velocity, which affects the efficient grinding and expulsion of woody biomass.
Innovation Solution
A vertical roller mill design featuring a flow-constricting flow path formed between a first and second flow-constricting ring, with an adjusting mechanism to control the gap dimension between them, ensuring that the flow velocity is optimized to prevent ungrinded materials from passing through while allowing grinded materials to be effectively transported.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow path area is reduced to increase flow velocity for improving woody biomass transport, then the exhaust performance is improved, but ungrinded materials can pass through the flow-constricting flow path
Solution Approach 1:
The flow-constricting structure is divided into multiple segments (first flow-constricting ring with outer peripheral portion and inner peripheral portion, second flow-constricting ring) that create a multi-stage flow path. This segmentation allows progressive constriction of the flow path, increasing velocity in stages while maintaining sufficient gap dimensions at each stage to prevent ungrinded materials from passing through.
Solution Approach 2:
Different portions of the flow-constricting rings have different gap dimensions tailored to their specific functions. The outer peripheral portion has a first gap dimension optimized for velocity increase, while the inner peripheral portion has a second gap dimension that prevents ungrinded material passage. This local differentiation of gap dimensions resolves the contradiction between velocity enhancement and material retention.
2Manufacturing precision
If the gap dimension in the flow-constricting flow path is reduced to prevent ungrinded materials from passing, then grinding quality is improved, but flow velocity decreases and woody biomass transport is hindered
Solution Approach 1:
The flow path constriction is achieved not only by reducing gap dimensions but also by extending the flow path length in the radial direction. The outer peripheral portion of the first flow-constricting ring extends radially outward, creating a longer flow path that compensates for larger gap dimensions. This dimensional approach allows maintaining larger gaps for material retention while still achieving sufficient velocity increase through path length extension.
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 design effectively inhibits the passage of ungrinded materials through the flow-constricting flow path, ensuring that only grinded biomass is transported, thereby improving the efficiency and effectiveness of the grinding process.
Implementation Method 1
a transport mechanism that forms an air flow for transporting, to the exhaust pipe, grinded materials obtained by grinding the materials to be grinded by the grinder
Implementation Method 2
a flow-constricting flow path that is provided between the grinder and the exhaust pipe and narrows a flow path area for the air flow, wherein the flow-constricting flow path is formed between a first flow-constricting ring provided in the center portion of the housing and a second flow-constricting ring provided to protrude from the housing toward the center portion of the housing
Data Source
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AI summary
A vertical roller mill (1) includes a housing (2), a chute (3) that supplies materials to be grinded to a center portion of the housing (2), a grinder (4) that is provided below the chute (3) and grinds the materials to be grinded, an exhaust pipe (9) that is provided above the grinder (4), a transport mechanism (6) that forms an air flow for transporting, to the exhaust pipe (9), grinded materials grinded by the grinder (4), and a flow-constricting flow path (10) provided between the grinder (4) and the exhaust pipe (9) and narrows a flow path area for the air flow, in which the flow-constricting flow path (10) is formed between a first flow-constricting ring (20) provided in the center portion of the housing (2) and a second flow-constricting ring (30) provided to protrude from the housing (2) toward the center portion of the housing (2).