High Consistency Pulping Flow Control
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Solution Overview
Problem
Conventional high consistency pulping methods often result in variable brightness and yield in recycled paper products due to over-pulping, which leads to irrecoverable brightness loss and difficulty in ink removal, as the fine inks reattach to fibers from frictional forces, making it challenging to produce high-quality pulps with low dirt content.
Innovation Solution
A method involving a pulping vessel with a rotor and flow sensors to monitor and control poloidal slurry flow, maintaining it above a lower threshold by adjusting energy input and viscosity through variable power and water addition, ensuring optimal pulping conditions to avoid over-pulping and maintain high yield and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high consistency pulping is used to increase productivity and reduce energy consumption, then pulping efficiency improves, but over-pulping occurs causing brightness loss and ink reattachment
Solution Approach 1:
The patent implements a feedback control system using flow sensors to monitor poloidal slurry flow in real-time during high consistency pulping. The sensor signals are fed to a controller that adjusts rotor power to maintain optimal flow conditions, preventing over-pulping while maximizing pulping efficiency. This closed-loop feedback mechanism enables precise control of the pulping process.
Solution Approach 2:
The patent dynamically changes operating parameters during pulping by adjusting rotor power based on monitored poloidal flow conditions. The system transitions from fixed-parameter pulping to variable-parameter pulping, where power input is continuously modified to maintain optimal flow velocity and direction, thereby controlling brightness and preventing ink reattachment while maintaining high productivity.
2Productivity
If increased energy input is applied to improve ink breakup, then ink removal efficiency improves, but fiber damage increases and brightness is lost
Solution Approach 1:
The feedback control system monitors poloidal flow conditions and adjusts rotor power accordingly, enabling precise control of mechanical energy input. This prevents excessive energy application that would cause fiber damage while maintaining sufficient energy for effective ink breakup. The system automatically reduces power when optimal flow conditions are achieved.
Solution Approach 2:
The patent employs dynamic power adjustment during the pulping cycle rather than constant high power input. The rotor power varies continuously based on real-time flow sensor feedback, creating an optimized energy input profile that maximizes ink breakup efficiency while minimizing fiber damage through controlled mechanical stress.
3Loss of energy
If poloidal flow is not maintained during pulping, then energy consumption decreases, but pulping quality deteriorates with variable brightness and yield
Solution Approach 1:
The feedback control system continuously monitors poloidal flow and adjusts rotor power to maintain optimal flow conditions throughout the pulping cycle. This ensures consistent pulp quality and brightness while avoiding energy waste from excessive power application. The system only consumes additional energy when flow conditions deviate from optima.
Solution Approach 2:
The patent optimizes energy consumption by dynamically adjusting rotor power parameters based on actual flow conditions rather than maintaining constant high power. The system changes power input levels to match process requirements, reducing energy waste during phases where optimal flow is already achieved while maintaining quality consistency.
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 approach effectively produces high-quality pulps with low ink content and high brightness by controlling energy input and viscosity, reducing the risk of over-pulping and enhancing the efficiency of ink breakup and fiber throughput, thereby improving the overall quality and yield of recycled paper products.
Implementation Method 1
monitoring poloidal slurry flow in the pulping vessel
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method of pulping wastepaper includes providing a pulping vessel with a rotor and at least one flow sensor to measure slurry flow within the pulping vessel. The pulping vessel is charged a slurry (wastepaper and water), the amounts of wastepaper and water being such that the slurry has consistency in the range of from 10% to 30%. The wastepaper charge in the pulping vessel is pulped at a pre-selected power level while monitoring poloidal slurry flow; water may be added when the poloidal flow falls below a predetermined lower threshold flow value to reduce viscosity and restore poloidal flow within the pulping vessel. Doppler velocimetry is a preferred method of monitoring pulp flow. In a particularly preferred construction the rotor has a variable power drive. The inventive method is especially useful for making high quality, high brightness furnishes from wastepaper which varies from batch to batch.