Refiner plate clash detection using an embedded force sensor

Olender, D.; Francescutti, Paul; Wild, Peter; Byrnes, Peter

doi:10.3183/npprj-2007-22-01-p124-130

Cited by 3 publications

(5 citation statements)

References 3 publications

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“…An advantage of the RFS-based system is that it is a direct, rather than indirect, indicator of contact between the discs. The use of the RFS signals to predict clash is described in a separate report [19].…”

Section: Resultsmentioning

confidence: 99%

“…Data acquired from these sensors have elucidated many aspects of the refining process that have until now, been hidden. For example, these sensors have been used to observe the effect of rotor tram on bar forces [18], to make an estimate of the mean residence time of the pulp in the refining zone [4], and also to give advanced warning of plate clashes [19]. By recording many thousands of barcrossings and studying their distributions, the general character of these impacts has also been revealed, including how their regularity and magnitude can vary due to machine scale and stage of refinement [5,20].…”

Section: Introductionmentioning

confidence: 99%

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A piezoelectric force sensor for mill-scale chip refiners

Olender

Wild

Byrnes

2008

Proceedings of the Institution of Mechanical Engineers, Part E:

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Refiners are used in the pulp and paper industry to separate wood chips into individual fibres and to develop the morphology of fibres to be suitable for the type and grade of paper to be produced. Within a refiner are discs, at least one of which rotates at high speed and all of which are lined with radial patterns of bars on their opposed surfaces. A mixture of chips and water is accelerated radially through the space between the discs. Compressive and shear forces are applied to chips and fibres as the bars on the opposed discs cross each other. Experiments have shown that certain process variables can greatly affect the forces applied to chips or fibres when bars cross. These findings suggest that the contact mechanics of bar-crossings are a significant factor in the development of fibre properties. To investigate these contact mechanics in operating refiners, a piezoelectric-based sensor has been developed to measure the forces applied to the chips and fibres by the bars. The sensor replaces a small section of a refiner bar and is sensitive to both axial and tangential forces. The current paper describes the evolution of the design of this sensor from a proof-of-concept prototype for a laboratory-scale refiner to the latest generation sensor for a mill-scale refiner. Performance during the most recent mill trials is presented.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A piezoelectric force sensor for mill-scale chip refiners

Olender

Wild

Byrnes

2008

Proceedings of the Institution of Mechanical Engineers, Part E:

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“…Olender developed a piezo ceramic refiner force sensor (RFS) based on the work of Siadat et al [10]. Olender's sensor was installed in a mill-scale refiner and in a pilot-scale refiner in the Andritz research center in Springfield, Ohio in the USA [26] and at the Catalyst Paper Corp. mill in Port Alberni, BC [29]. The sensor replaces a short length (5 mm) of the stator bar and houses two piezo ceramic elements that generate electric charge, which is converted to a measurable voltage with a charge amplifier, when submitted to a force.…”

Section: Inletmentioning

confidence: 99%

“…Further, Olender investigated the prediction of plate clash based on force sensor data. They were able to detect plate clash events several seconds before a commercial accelerometer-based system in both refiners [29].…”

Section: Inletmentioning

confidence: 99%

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Effects of plate wear on bar forces and fiber properties in a mill scale LC-refiner

Aigner

Olson

Sun

et al. 2021

Nordic Pulp &Amp; Paper Research Journal

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A set of piezo electric force sensors is implemented in a 52-inch mill-scale low consistency refiner to explore the effect of refiner plate wear on bar force sensor measurements. The sensor replaces a short length of a stator bar and measures normal and shear forces applied during the passage of each rotor bar. In previous work with this type of force sensor, force profiles for individual bar passing events (BPE) were investigated. In the work presented here, force profiles for individual BPEs are identified based on key features in the time domain force data. The individual bar force profiles are classified as single peak events which feature one peak corresponding to the fiber compression force and as dual peak events corresponding to fiber compression force and the corner force. The bar passing events are then analysed, based on dual peak ratio and time to peak of the early peak in the dual peak events. Force measurements are evaluated over the full run time of a set of refiner plates. Findings are compared with refiner plate wear measurements and discharge fiber analysis. It is shown that the decrease in the prevalence of the corner force correlates with the wear of the leading edge of the refiner bars or bar rounding of the run time of the refiner plate. This is accompanied by a decrease in plate performance which is represented by a decrease in fiber length and freeness reduction for the same refiner load.

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Measurement and interpretation of spatially registered bar-forces in LC refining

Aigner

Olson

Wild

2020

Nordic Pulp &Amp; Paper Research Journal

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A high resolution rotary encoder and a piezo electric force sensor are implemented in a 16-inch laboratory-scale low consistency refiner to explore the effect of plate gaps on bar-force profiles. The sensor replaces a short length of a stator bar and measures normal and shear forces applied during the passage of each rotor bar. The rotary encoder data is used to locate the rotor bars relative to the stator bar in which the sensor is located. Previous work with this type of force sensor focuses primarily on the distribution of the maximum force measured during the passage of each rotor bar over the sensor or bar passing event, BPE. In this work, force profiles for bar passing events are registered to the position of rotor bars relative to the stator bar in which the sensor is located. These registered force profiles are measured for a range of plate gaps and two different pulp furnishes. The angular reference provided by the encoder makes it possible to generate mean force profiles. As force data for individual BPEs is highly variable, these mean force profiles have potential to shed light on the fundamental mechanisms of mechanical refining. For large gaps, there is a late peak in the force profiles that occurs toward the end of the bar passing event. For gaps that are less than the critical gap, below which fiber cutting occurs, there is an early peak in the force profiles that occurs at the start of the bar passing event. It is hypothesized that the early peak represents the corner force and, therefore, that corner force is causal in the onset of fiber cutting. To explore this hypothesis, a model is presented connecting corner force and friction force to the progression geometric variables during the bar passing event such as the bar edge length engaged at any point in the bar passing event and the area covered by the rotor bar on the force sensor at any point in the bar passing event.

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Refiner plate clash detection using an embedded force sensor

Cited by 3 publications

References 3 publications

A piezoelectric force sensor for mill-scale chip refiners

A piezoelectric force sensor for mill-scale chip refiners

Effects of plate wear on bar forces and fiber properties in a mill scale LC-refiner

Measurement and interpretation of spatially registered bar-forces in LC refining

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