Segmented Screw Pipe for Cellulose Pulp Feeding and Dewatering
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Solution Overview
Problem
Existing plug screw feeders in the pulp and paper industry face inefficiencies in both feeding and dewatering cellulose pulp/chips, particularly when using spiral screw pipes, which compromise dewatering efficiency and are not compatible with slotted plug pipes with straight bars.
Innovation Solution
A screw pipe design with bars inclined at an angle that decreases from the inlet to the outlet end, transitioning from helical to substantially parallel, allowing for efficient feeding and enhanced dewatering, and compatible with slotted plug pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spiral bars are used in the screw pipe, then feeding efficiency is improved, but dewatering efficiency deteriorates
Solution Approach 1:
The screw pipe is divided into multiple sections along its length, with each section having bars at different angles. The first section has bars inclined at a larger angle for feeding, while subsequent sections have bars at progressively smaller angles for dewatering, allowing both functions to be performed in sequence
Solution Approach 2:
Different sections of the screw pipe are given different local characteristics - the inlet section has highly inclined bars optimized for feeding, while the outlet section has nearly parallel bars optimized for dewatering, with intermediate sections providing a gradual transition
2Productivity
If spiral screw pipes are used, then feeding effect is improved, but compatibility with slotted plug pipes deteriorates
Solution Approach 1:
The screw pipe is segmented into sections with varying bar angles, with the final section having bars that are substantially parallel to the longitudinal axis, matching the configuration of slotted plug pipes and ensuring compatibility between components
Solution Approach 2:
The bar angle configuration transitions dynamically from highly inclined at the inlet to substantially parallel at the outlet, allowing the screw pipe to adapt its characteristics along its length to match different downstream components
Data Source
AI summary
A screw pipe unit intended to cooperate with and at least partly enclose a screw in a plug screw feeder for cellulose chips/pulp is provided. The screw pipe unit comprises a plurality of openings for filtrate dewatered from the chips/pulp in the screw pipe when the plug screw feeder is in operation. The screw pipe is, on at least a portion of its inner surface, provided with bars inclined with respect to the longitudinal axis of the screw pipe. The angle of inclination of the bars decreases in the longitudinal direction, from a first portion of the screw pipe unit with maximum inclination to a second portion of the screw pipe unit with bars substantially parallel to the axis, the second portion being further away from the inlet end of the screw pipe unit than the first portion.