Pulp Screening Reject Recycle to Impregnation
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Solution Overview
Problem
Existing pulping methods generate a significant amount of reject fraction during the screening process, which requires separate treatment and increases energy consumption and equipment usage.
Innovation Solution
A method where at least part of the reject fraction from the screening step is directed back to the impregnating step or a preceding step, allowing for further processing and reducing the need for a separate reject treatment line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate reject treatment line is used to process reject fraction, then the reject fraction can be properly treated, but energy consumption and equipment usage increase
Solution Approach 1:
The patent merges the reject fraction back into the main process stream by directing it to the impregnating step or a preceding step. This eliminates the need for a separate reject treatment line, combining multiple process functions into a unified flow that reduces energy consumption and equipment requirements while maintaining effective reject fraction handling.
Solution Approach 2:
Instead of discarding the reject fraction to a separate treatment line, the patent recovers it by redirecting back to the impregnating step. This recovery approach allows the reject fraction to be reprocessed and integrated back into the productive stream, eliminating waste and reducing the need for additional treatment equipment.
2Reliability
If a separate reject treatment line is used, then reject fraction can be processed, but device complexity increases
Solution Approach 1:
The patent merges the reject fraction handling into the existing main process flow by redirecting it to the impregnating step. This eliminates the need for separate reject treatment equipment, reducing device complexity while maintaining reliable reject fraction processing through the integrated system.
3Use of energy by moving object
If reject fraction is directed back to impregnating step, then energy is saved and equipment usage is reduced, but the process flow becomes more complex
Solution Approach 1:
The patent recovers the reject fraction by redirecting it to the impregnating step, transforming what would be waste into a reusable stream. This recovery approach saves energy by avoiding separate treatment processes while the integrated feedback loop simplifies the overall process flow compared to maintaining separate treatment lines.
4Use of energy by moving object
If disc filter is dispensed with, then energy consumption is reduced, but dewatering capability must be maintained
Solution Approach 1:
The patent extracts the dewatering function from the disc filter by redirecting the reject fraction back to the impregnating step, where it is processed differently. This eliminates the need for the disc filter while maintaining effective dewatering through the alternative processing path, reducing energy consumption associated with disc filter operation.
Data Source
AI summary
According to an example aspect of the present invention, there is provided a method comprising: providing a pulp composition; screening the pulp composition to obtain an accept fraction and a reject fraction; and dewatering the accept fraction output from the screening by a screw press.