Variable Speed Refiner Control for Pulp Quality and Energy Efficiency
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Solution Overview
Problem
Traditional refiner control systems are slow to react to variations in pulp quality and energy input, leading to inconsistent pulp quality and inefficient energy use, as they rely on limited measurements such as specific energy and motor load, which do not account for spatial energy consumption or local process conditions.
Innovation Solution
Implementing a variable speed motor control system with sensors in the refining zone, using multivariable control methods to adjust motor speed and inlet pressure, allowing for continuous optimization of pulp quality and energy use based on real-time internal and external state measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional refiner control systems use limited measurements (specific energy and motor load), then the control system is simple, but the pulp quality consistency deteriorates and energy efficiency worsens
Solution Approach 1:
The patent implements a feedback control system that continuously measures multiple process variables (temperature, pressure, flow rates, motor load, specific energy) and uses this information to adjust refiner operations in real-time, thereby improving pulp quality consistency while maintaining reasonable system complexity through systematic feedback loops
Solution Approach 2:
The patent introduces intermediate measurement devices (sensors for temperature, pressure, flow rates) that mediate between the physical refining process and the control system, providing comprehensive data about internal and external states without requiring direct complex measurement of all process parameters
2Loss of energy
If refiner control systems react slowly to variations in pulp quality and energy input, then the control system is simple, but the energy efficiency deteriorates and pulp quality consistency worsens
Solution Approach 1:
The patent implements continuous measurement and control of multiple process variables (temperature, pressure, flow rates, motor load, specific energy) rather than periodic or delayed measurements, ensuring that energy optimization actions are taken continuously based on real-time process conditions, thereby improving energy efficiency and control response speed
3Use of energy by moving object
If traditional control systems rely on limited measurements, then the measurement system is simple, but the energy efficiency deteriorates
Solution Approach 1:
The patent segments the measurement system into multiple independent sensors measuring different process variables (temperature, pressure, flow rates, motor load, specific energy) rather than using a single comprehensive measurement device, allowing precise measurement of internal and external states without requiring overly complex single-point measurement systems
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 stabilizes pulp quality and reduces energy consumption by enabling precise control of refiner speed and pressure, optimizing energy input and maintaining consistent pulp quality across varying production speeds.
Implementation Method 1
The bars act with shear forces that defibrate and defibrillate chips or further refine the already produced pulp
Implementation Method 2
Each motor is provided with a variable speed controller arranged to manipulate the speed of the motor continuously
Implementation Method 3
measuring, alternatively estimating, one or more process variables representing external states outside of the refiner for the process section and determining a value for said one or more process variables
Data Source
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AI summary
A method is described for controlling a process section for refining fibrous material such as wood pulp, cellulose pulp and the like. The process section has a refiner driven by a motor of which the speed is variable. Using a multivariable control method the process may be optimised for energy by varying the rotation speed of the refiner. The process section may also have 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 may also comprise measuring, alternatively estimating, one or more process variables representing external states outside of the refiner (?1,Q1) for said process section and measuring, alternatively estimating, one or more values representing one or more internal states (?1) inside said at least one first refiner, and by calculating a change for said at least one manipulated variable (u1) for said at least one refiner using said measurement of an internal state (?1) of said at least one refiner and a measurement of said one or more process external states (n1,Q1) for said process section by means of a mathematical process model.