Unobstructed Screen Grid for High Pressure Feeder
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Solution Overview
Problem
Conventional high pressure feeders (HPFs) experience reduced efficiency and capacity due to obstructions in the low pressure outlet flow, caused by misalignment of the screen grid and divider bar, leading to blocked liquor flow and decreased chip filling in the rotor.
Innovation Solution
The solution involves expanding the slotted area of the screen grid to cover the entire low pressure outlet, removing the center bar in the liner, and creating a gap between the divider bar and the screen grid to ensure unobstructed liquor flow, with wider slot openings (8-25 mm) and a shortened divider bar to enhance fluid flow and chip processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the screen grid has a narrow solid section aligned with the divider bar to minimize flow obstruction, then the alignment is optimized when the rotor is in the initial position, but the alignment becomes misaligned when the rotor moves axially to compensate for wear, causing flow obstruction
Solution Approach 1:
The patent changes the geometric parameters of the screen grid by replacing the narrow solid section with a wide solid section that has a larger width than the divider bar. This parameter change ensures that the screen grid maintains proper alignment with the rotor outlets over the entire axial movement range, preventing flow obstruction while accommodating rotor wear compensation
Solution Approach 2:
The screen grid is divided into distinct functional sections: a wide solid section for stable alignment with the rotor outlets, a first slotted section for liquor discharge, and a second slotted section for additional flow capacity. This segmentation allows each section to perform its specific function optimally while maintaining overall alignment stability
2Ease of manufacture
If the screen grid has dual screen grids with slots that do not extend continuously over the entire area to simplify construction, then manufacturing is easier, but solid sections obstruct the low pressure flow of liquor, reducing efficiency and capacity
Solution Approach 1:
The patent implements continuous slotted sections that extend across the entire width of the screen grid, allowing uninterrupted liquor flow from one side to the other. This continuous slotted design eliminates the flow obstructions caused by discrete, non-continuous slots while maintaining manufacturing feasibility through standardized construction methods
3Manufacturing precision
If the center solid portion of the screen grid and divider wall are aligned with the center of the rotor to minimize initial flow obstruction, then initial alignment is optimized, but axial movement of the rotor causes misalignment and flow obstruction
Solution Approach 1:
The patent changes the dimensional parameters of the solid section from narrow to wide, creating a tolerance zone that accommodates axial rotor movement. The wide solid section's larger width provides a buffer that maintains proper alignment even when the rotor shifts axially to compensate for wear, thereby increasing adaptability while preserving manufacturing precision
Data Source
AI summary
A rotary high pressure feeder for feeding cellulosic fibrous material including: a rotor rotatable about an axis and comprising at least one pocket having a conduit extending through the rotor in a direction perpendicular to the axis and having end openings at opposite ends of the pocket, wherein each of said end openings of each pocket functions as both an inlet and outlet depending upon an angular position of the rotor within a housing; the housing encloses said rotor and said housing includes a low pressure inlet port and a low pressure outlet port radially opposed to the low pressure inlet port, and a high pressure inlet port and a high pressure outlet port aligned horizontally, wherein the ports are arranged on the housing for registry with the end openings of at least one pocket, and a screen grid seated in or adjacent to the low pressure outlet port, wherein the screen grid includes an array of screen slots and bars forming a uniform pattern of slots and bars extending without interruption across an entirety of the low pressure outlet port.