Brown Stock Washing Control Using Refractive Index Dosing
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Solution Overview
Problem
Existing brown stock washing processes lack effective methods to accurately quantify total black liquor carryover, particularly the organic fraction, leading to inefficiencies in bleaching and increased chemical consumption.
Innovation Solution
Measure the refractive index and conductivity of brown stock to determine total dissolved solids, allowing for precise control of drainage aid and defoamer dosing, thereby minimizing black liquor carryover and optimizing bleaching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual control or pounds per ton control is used for wash aid dosing, then operation simplicity is maintained, but measurement precision of black liquor carryover and washing effectiveness deteriorates
Solution Approach 1:
The patent replaces manual mechanical control systems with optical measurement systems (refractometer and conductivity meter) to automatically measure black liquor carryover. This substitution enables precise quantitative measurement of organic and inorganic fractions without requiring complex manual intervention or pounds-per-ton calculations.
Solution Approach 2:
The patent introduces refractive index and conductivity measurements as intermediary parameters to indirectly quantify black liquor carryover. These measurements serve as mediators between the physical state of brown stock and the control system, enabling precise measurement without directly analyzing black liquor composition.
2Productivity
If constant wash aid flow rate is used, then ease of operation is maintained, but productivity and washing effectiveness deteriorate due to inability to respond to process changes
Solution Approach 1:
The patent implements a feedback control system where refractometer and conductivity meter measurements continuously monitor brown stock composition, and the control system automatically adjusts wash aid pump flow rates in response to measured changes. This closed-loop feedback enables productivity optimization while maintaining ease of operation through automated control.
Solution Approach 2:
The patent transitions from static constant flow rate control to dynamic flow rate control that automatically adjusts wash aid dosing based on real-time measurements of brown stock characteristics. This dynamic adjustment optimizes washing effectiveness and productivity while the automated system maintains ease of operation.
3Measurement precision
If no measurement of organic fraction is used, then device complexity is reduced, but measurement precision of total black liquor carryover deteriorates
Solution Approach 1:
The patent segments black liquor carryover measurement into two distinct components: organic fraction (measured by refractive index) and inorganic fraction (measured by conductivity). This segmentation allows precise measurement of total carryover by summing the two fractions, while using simple, separate measurement devices rather than a single complex instrument.
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
Enhances bleaching efficiency by accurately measuring organic and inorganic fractions, reducing chemical consumption, and improving papermaking process efficiency.
Implementation Method 1
measuring a refractive index of the brown stock
Implementation Method 2
measuring a conductivity of the brown stock
Data Source
AI summary
A method of treating brown stock in a brown stock washing process is provided. The method includes measuring a refractive index of a brown stock; and dosing an additive to the brown stock according to at least the refractive index of the brown stock. A system for controlling dosing of an additive to a brown stock washing process is also provided. The system includes a refractive index measurement device; a controller configured to receive data provided by the refractive index measurement device and transform the data into additive addition output instructions; and an additive delivery unit configured to receive and execute the additive addition output instructions from the controller.