ISO/TR 11371:2013
(Main)Pulps — Basic guidelines for laboratory refining
Pulps — Basic guidelines for laboratory refining
ISO/TR 11371:2013 gives guidelines for the laboratory refining of various pulps intended for paper production including unifying terms and parameters for the simulation of industrial refining processes and laboratory refiners; treating pulp samples in a (semi) continuous operation in contrast to quasi-stationary laboratory beating equipment such as the PFI mill or Valley Hollander; evaluation of chemical market pulps under close-to-reality conditions in terms of refining intensity and refining energy consumption; optimizing of fibre furnishes in terms of cost, quality, and energy requirements; and this Technical Report only considers refiners operating at low consistency.
Pâtes — Lignes directrices pour le raffinage de laboratoire
General Information
Relations
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 11371
First edition
2013-10-15
Pulps — Basic guidelines for
laboratory refining
Pâtes — Lignes directrices pour le raffinage de laboratoire
Reference number
ISO/TR 11371:2013(E)
©
ISO 2013
---------------------- Page: 1 ----------------------
ISO/TR 11371:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 11371:2013(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Basics of pulp refining . 1
3 Terms, abbreviation and definitions . 2
3.1 Machine parameters. 2
3.2 Refiner fillings parameters . 3
3.3 Refining process parameters . 3
3.4 Definition of refining intensity . 3
4 Laboratory refining procedures . 6
4.1 Pulp preparation. 7
4.2 Refining system . 8
4.3 Measurements . 9
4.4 Sample evaluation .10
4.5 Parameters .11
4.6 Maintenance .11
4.7 Quality assurance.11
5 Summary and guidelines .12
Annex A (informative) Trial Report .13
Annex B (informative) Report on pulp testing .15
Bibliography .17
© ISO 2013 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TR 11371:2013(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 6, Paper, board and pulps, Subcommittee SC 5.
iv © ISO 2013 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 11371:2013(E)
Introduction
It is well known that the current standardized methods (PFI, Valley, Jokro, …) for refining/beating have
only limited value in the evaluation of chemical pulps. They were originally developed for quality control
purposes and have no counterpart in real mill operations.
The biggest shortcomings involved are the following:
— refining mode (energy consumption, refining intensity) is different from mill-scale refining processes;
— no possibility to adjust refining parameters for specific pulps;
— no direct measure for specific energy consumption.
These well-known standardized methods have fairly good reproducibility and repeatability and the
equipment is easily handled. Nevertheless, many laboratories have replaced these methods by the use
of so-called simulating laboratory refiners, which allow the evaluation of pulps for various mill-scale
refining applications. No uniform methods for simulating refining have so far been established on an
international scale.
© ISO 2013 – All rights reserved v
---------------------- Page: 5 ----------------------
TECHNICAL REPORT ISO/TR 11371:2013(E)
Pulps — Basic guidelines for laboratory refining
1 Scope
This Technical Report gives guidelines for the laboratory refining of various pulps intended for paper
production including:
— unifying terms and parameters for the simulation of industrial refining processes and laboratory
refiners;
— treating pulp samples in a (semi) continuous operation in contrast to quasi-stationary laboratory
beating equipment such as the PFI mill or Valley Hollander;
— evaluation of chemical market pulps under close-to-reality conditions in terms of refining intensity
and refining energy consumption;
— optimizing of fibre furnishes in terms of cost, quality, and energy requirements;
— this Technical Report only considers refiners operating at low consistency.
2 Basics of pulp refining
Chemical pulps are seldom suitable for a specific end use as such. Refining is the most important process
where the fibre properties are tailored to meet the demands of various paper and paperboard products.
The main target of refining is to improve the bonding ability of the fibres to enhance runnability and
to give the paper good printing properties. Other targets can be, for example, to shorten fibres which
can be too long, to give good sheet formation or to develop specific paper properties such as porosity or
optical properties.
The most common refining method for chemical pulps is to treat the pulp suspension with metallic
bars at low consistency. The bars are attached to a stationary element (stator) and to a rotary element
(rotor). The pulp fibres pass through the gap between the rotor and the stator receiving impacts with
varying number and intensity. In industrial refiners, the refining elements (fillings) can be disks, cones,
or cylinders.
The fibres are affected by refining in several ways; the most common ones are as follows:
— cutting of the fibres;
— formation of fines by removing parts from fibre walls;
— external fibrillation giving the fibres a “hairy” look;
— internal changes in the fibre wall (internal fibrillation, swelling, or delamination);
— straightening or curling the fibre;
— creating or removing kinks, nodes, or microcompressions in the fibre wall;
— dissolving or leaching out colloidal material into the water phase;
— redistribution of hemicelluloses in the fibre wall from the interior to the exterior parts;
— formation of a gelatinous layer at the fibre surfaces.
© ISO 2013 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/TR 11371:2013(E)
As a result, the fibres become more flexible and conformable and their bonding area is increased. This is
reflected in the pulp and sheet properties as follows:
— water removal in sheet forming is decreased (drainage resistance increased);
— strength properties promoted (tensile properties, burst, Z-directional strength, fracture toughness
are increased);
— tear strength is increased or decreased depending on fibre characteristics and the extent of refining;
— structural properties (bulk, air permeability, and absorbency) are decreased;
— optical properties (light-scattering ability, opacity) are decreased, brightness only slightly.
3 Terms, abbreviation and definitions
The refining is affected by machine, refiner fillings, and process parameters listed in 4.1–4.3.
3.1 Machine parameters
Term Abbreviation Unit Definition
Installed motor power P kW Installed motor power of refiner main drive
m
Measured power requirement of the refiner, with the fill-
Total load power P kW ings applied, under refining conditions, in the presence of
tot
a fibre suspension – constant gap
Power requirement for friction and pumping. Measured in
No-load power P kW water or fibre suspension in defined conditions for flow
0
and open gap
Net refining power P kW Difference between total load power and no-load power
net
1/min,
Refiner rotational speed n Revolutions of the refiner rotor per minute/second
1/s
Velocity of the rotor at the outer diameter of the refining
zones of the refining elements at a defined refiner rota-
Average peripheral velocity v m/s tional speed. Sometimes defined as the velocity of a point
at half-length of the refining zones of the refining elements
at a defined refiner rotational speed.
2 © ISO 2013 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TR 11371:2013(E)
3.2 Refiner fillings parameters
Term Abbreviation Unit Definition
Tools used for pulp refining, including a stationary ele-
Refiner fillings ment (stator) and a rotating element (rotor) in the form of
a plate or cone with bars and grooves
Rotor Motor-driven (rotating) element of refiner fillings
Stator Stationary element of refiner fillings
Fillings segment Removable or exchangeable part of rotor or stator
Element cast, fabricated or machined onto the fillings
Bar surfaces which provide for pulp refining and transport of
fibre suspension
Bar width bw mm Width of a single bar on bar top
Total number of bars on the refiner fillings (rotor or sta-
Number of bars
tor)
Area of refiner fillings segment – the sector or cluster
Fillings sector angle, in which the bars/grooves are paired. Many sectors
added to one another make a full disc.
Arithmetic average of the minimum and maximum angle
Bar angle ° between the middle line of a certain bar and radial lines
over the start and end point of the bar
Sum of the average rotor bar angle and the average stator
Average cutting angle °
bar angle
Total length of all bar edges in kilometers either per revo-
km/rev,
Cutting edge length CEL lution in the running refiner or per second in the running
km/s
refiner at a defined refiner rotational speed
Total length of all bar edges in meters per second in the
Cutting length factor CLF m/s/rpm
running refiner at a refiner rotational speed of 1 rpm
Grooves Channels between bars
Groove width gw mm Width of the groove, synonymous with bar spacing
Distance between the upper edge of the bar and base
Groove depth mm
plate/base cone surface
There are various types of plates (cast, fabricated, and
machined) having different metallurgy (supplied by the
Bar material and sharpness
manufacturer). Bar sharpness greatly affects the refining
result and should be checked regularly.
3.3 Refining process parameters
Term Abbreviation Unit Definition
Distance between the top surface of rotor and sta-
Refining gap mm, µm
tor bars
Period of time from the start of refining to sam-
Refining time min, s
pling or interval between two samplings
Flow f l/h, l/min, l/s Fibre suspension flow through the refiner
Refining intensity l Various ways to describe (see formulas)
Specific (net) energy con- Net refining energy consumption related to the
SRE kWh/t
sumption oven-dry mass of fibres treated
3.4 Definition of refining intensity
The refining result achieved for a pulp depends on many factors as mentioned earlier. Several models
and theories, the first ones dating back to over a century, have been developed to describe the refining
action. Usually they are based on describing refining by two factors: specific energy and refining
© ISO 2013 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/TR 11371:2013(E)
intensity. The specific energy is relatively easily measured but varying approaches have been used to
describe the intensity.
3.4.1 Specific edge load (SEL)
The specific edge load theory published by Brecht et al. (see Reference [2]) is based on the idea that all the
refining energy is transferred to the fibres by the bar edges. The parameters calculated are the net energy
consumption, SRE [Formula (1)], and specific edge load describing the intensity, SEL [Formula (2)].
PP− P
totn0 et
SER= = (1)
fc× fc×
where
SRE specific refining energy (kWh/t o.d.);
P total load power (kW);
tot
P no-load power (kW);
0
P net refining power (kW);
net
3
f
flow (m /h);
c
3
consistency (t/m ).
PP− P P
tot 0 netnet
SEL= = = (2)
nZ××Zl× nC× LF CEL
rst
where
SEL specific edge length (J/m);
P total load power (kW);
tot
P no-load power (kW);
0
P net refining power (kW);
net
n
rotation speed (revs/s);
Z number of rotor bars;
r
Z
number of stator bars;
st
l
bar length (km);
CEL cutting edge length (km/s);
CLF cutting length factor (km/rev).
The specific edge load is still the most common way to describe refining intensity. It is a “machine
intensity”, well known to work well when identical refiners are compared with the same pulps and
refining conditions. It is in essence the energy per unit bar length per bar crossing.
4 © ISO 2013 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/TR 11371:2013(E)
3.4.2 Specific surface load (SSL)
The specific surface load theory developed by Lumiainen (see Reference [3]) is based on the idea that,
in addition to bar length, bar width also affects the refining result. The energy is transferred to pulp
fibres not only during the short edge-to-edge contact phase but also during the edge-to-surface phase.
The specific surface load (SSL) value is obtained by dividing the specific edge load (SEL) by the bar width
factor, length of the r
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.