Refiner Plate Sensor Array for Pulp Quality Control
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Solution Overview
Problem
Traditional control systems for refiners in the pulp and paper industry are slow and lack reliable control over pulp quality, as they primarily rely on specific energy or motor load measurements, which do not provide sufficient information about local process conditions, leading to difficulties in maintaining consistent pulp quality at minimum energy input.
Innovation Solution
The method involves using a plurality of sensors on a refiner plate to measure and estimate internal and external process variables, employing mathematical process models described by nonlinear differential equations, Laplace transforms, or transfer functions to manipulate variables and optimize pulp quality, with a focus on internal states like temperature and pressure measurements within the refining zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional control systems use specific energy or motor load measurements, then the control system is simple to implement, but the control precision and reliability of pulp quality is insufficient
Solution Approach 1:
The patent introduces temperature and pressure sensors as intermediary measurement devices that indirectly reflect the refining zone conditions and pulp quality state. These sensors act as mediators between the complex refining process and the control system, providing measurable parameters that correlate with pulp quality without requiring direct measurement of quality attributes. This resolves the contradiction by enabling precise quality control through intermediary physical parameter measurements.
Solution Approach 2:
The patent replaces traditional mechanical/specific energy-based control measurements with thermal and pressure field measurements. By substituting motor load measurements with temperature and pressure sensor data from the refining zone, the system achieves more direct and reliable quality control information. This substitution enables better control precision while maintaining manageable system complexity through standardized sensor technologies.
2Speed
If traditional control systems rely on motor load measurements, then the measurement system is simple, but the response speed and accuracy of pulp quality control is slow
Solution Approach 1:
The patent places temperature and pressure sensors directly in the refining zone to measure process conditions at the point of action, before the pulp exits the refiner. This preliminary measurement of internal zone conditions allows the control system to detect and respond to process changes immediately, rather than waiting for downstream quality measurements. This resolves the contradiction by enabling fast response through advance measurement of critical process parameters.
Solution Approach 2:
The patent implements a feedback control loop where temperature and pressure measurements from the refining zone are continuously monitored and used to adjust refiner operations in real-time. This closed-loop feedback system enables rapid response to process deviations, improving both control speed and accuracy by continuously comparing actual conditions with target values and making immediate corrections.
3Manufacturing precision
If traditional control systems use average specific energy measurements, then the measurement is easy to obtain, but the ability to handle spatial variations and non-linearities in the refining zone is insufficient
Solution Approach 1:
The patent divides the refining zone into multiple measurement locations by placing several temperature and pressure sensors at different positions within the zone. This segmentation of the measurement system allows detection of spatial variations in process conditions that would be averaged out by single-point measurements. The segmented measurement approach enables precise control of pulp quality consistency by identifying and correcting local process deviations.
Solution Approach 2:
The patent transitions from single-point average measurements to multi-dimensional spatial measurements by distributing sensors throughout the refining zone. This adds the dimension of spatial resolution to the measurement system, enabling detection of non-linearities and local variations in temperature and pressure fields. This dimensional expansion of measurement capability directly improves manufacturing precision by revealing and controlling previously undetected process variations.
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 enables faster and more accurate control of pulp quality and energy input, handling non-linearities and spatial variations, resulting in improved controllability and energy efficiency compared to traditional methods.
Implementation Method 1
measuring, alternatively estimating, one or more values representing one or more internal states inside said at least one first refiner, wherein said at least one first refiner comprises a plurality of sensors arranged in a predetermined position on a refiner plate of said at least one first refiner
Implementation Method 2
measuring, alternatively estimating, one or more values representing one or more internal states inside said at least one first refiner
Implementation Method 3
The static refiner plate 3, or stator, is usually pushed towards the rotating one 4, or rotor... The grinding zone or as it is often called the refining zone... The bars act as knives that defibrillate chips or further refine the already produced pulp
Implementation Method 4
When refining wood chips or previously refined pulp the refiner plates are typically pushed against each other to obtain a plate gap of approximately 0.2-0.7 mm
Implementation Method 5
HC refining has three phases; chips/pulp, water and steam... In an HC refiner, fibers, water and steam is also transported in the troughs between the bars... both water and steam may exist together with chips/pulp in the refining zone
Data Source
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AI summary
A method is described for controlling a process section for thermo-mechanical pulp (TMP) refining. The process section has at least one first refiner having a plurality of sensors arranged in a predetermined position on a refiner plate of the at least one first refiner. The method comprises measuring, alternatively estimating, one or more process variables representing external states outside of the refiner Formula (I) for said process section and measuring, alternatively estimating, one or more values representing one or more internal states states Formula (II) inside said at least one first refiner, and by calculating a change for said at least one manipulated variable (u 1 ) for said at least one refiner using said measurement of an internal state Formula (II) of said at least one refiner and a measurement of said one or more process external states Formula (I) for said process section by means of a mathematical process model.