1、 ISO 2013 Pulps Basic guidelines for laboratory refining Ptes Lignes directrices pour le raffinage de laboratoire TECHNICAL REPORT ISO/TR 11371 First edition 2013-10-15 Reference number ISO/TR 11371:2013(E) ISO/TR 11371:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All
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4、ed iii 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 .
5、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/TR 11371
6、: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
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12、ary information The committee responsible for this document is ISO/TC 6, Paper, board and pulps, Subcommittee SC 5.iv ISO 2013 All rights reserved ISO/TR 11371:2013(E) Introduction It is well known that the current standardized methods (PFI, Valley, Jokro, ) for refining/beating have only limited va
13、lue 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 proc
14、esses; 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
15、 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 Pulps Basic guidelines
16、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) co
17、ntinuous 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 co
18、st, 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 de
19、mands 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
20、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 f
21、ibres 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: cutti
22、ng 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 microcompr
23、essions 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. TECHNICAL REPORT ISO/TR 11371:2013(E) ISO 2013 All rights
24、reserved 1 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 (
25、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-scatter
26、ing 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 4.14.3. 3.1 Machine parameters Term Abbreviation Unit Definition Installed motor power P m kW Installed motor p
27、ower of refiner main drive Total load power P tot kW Measured power requirement of the refiner, with the fill- ings applied, under refining conditions, in the presence of a fibre suspension constant gap No-load power P 0 kW Power requirement for friction and pumping. Measured in water or fibre suspe
28、nsion in defined conditions for flow and open gap Net refining power P net kW Difference between total load power and no-load power Refiner rotational speed n 1/min, 1/s Revolutions of the refiner rotor per minute/second Average peripheral velocity v m/s Velocity of the rotor at the outer diameter o
29、f the refining zones of the refining elements at a defined refiner rota- 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 ISO/TR 11371:2013(E) 3.2 Refiner fill
30、ings parameters Term Abbreviation Unit Definition Refiner fillings Tools used for pulp refining, including a stationary ele- 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 e
31、lement of refiner fillings Fillings segment Removable or exchangeable part of rotor or stator Bar Element cast, fabricated or machined onto the fillings surfaces which provide for pulp refining and transport of fibre suspension Bar width bw mm Width of a single bar on bar top Number of bars Total nu
32、mber of bars on the refiner fillings (rotor or sta- tor) Fillings sector Area of refiner fillings segment the sector or cluster angle, in which the bars/grooves are paired. Many sectors added to one another make a full disc. Bar angle Arithmetic average of the minimum and maximum angle between the m
33、iddle line of a certain bar and radial lines over the start and end point of the bar Average cutting angle Sum of the average rotor bar angle and the average stator bar angle Cutting edge length CEL km/rev, km/s Total length of all bar edges in kilometers either per revo- lution in the running refin
34、er or per second in the running refiner at a defined refiner rotational speed Cutting length factor CLF m/s/rpm Total length of all bar edges in meters per second in the running refiner at a refiner rotational speed of 1 rpm Grooves Channels between bars Groove width gw mm Width of the groove, synon
35、ymous with bar spacing Groove depth mm Distance between the upper edge of the bar and base plate/base cone surface Bar material and sharpness There are various types of plates (cast, fabricated, and machined) having different metallurgy (supplied by the manufacturer). Bar sharpness greatly affects t
36、he refining result and should be checked regularly. 3.3 Refining process parameters Term Abbreviation Unit Definition Refining gap mm, m Distance between the top surface of rotor and sta- tor bars Refining time min, s Period of time from the start of refining to sam- pling or interval between two sa
37、mplings 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- sumption SRE kWh/t Net refining energy consumption related to the oven-dry mass of fibres treated 3.4 Definition of refining intensity The
38、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
39、 ISO 2013 All rights reserved 3 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
40、 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). 0(1) where SRE specific refining energy (kWh/t o.d.); total load power (kW);
41、P 0 no-load power (kW); net refining power (kW); f flow (m 3 /h); c consistency (t/m 3 ). 0(2) where SEL specific edge length (J/m); total load power (kW); P 0 no-load power (kW); net refining power (kW); n rotation speed (revs/s); number of rotor bars; number of stator bars; l bar length (km); CEL
42、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
43、the energy per unit bar length per bar crossing.4 ISO 2013 All rights reserved 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 re
44、sult. 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 refining impact (IL), see F
45、ormula (3). (3) where SSL specific surface load (J/m 2 ); SEL specific edge load (J/m); IL bar width factor (m). The bar width factor is calculated from the bar width and the angular setting of the bars, see Formula (4). (4) where IL bar width factor (m); rotor bar width (m); stator bar width (m); a
46、verage intersecting angle (). The specific surface load theory works better than the specific edge load theory when similar refiners with varying fillings are compared. Both theories still have weak points, but both offer practical tools in selecting fillings and other refining parameters. 3.4.3 Mod
47、ified edge load (MEL) Meltzer et al. developed the modified edge load theory (see Reference 4), where the traditional specific edge load was corrected by factors taking the bar and groove width and cutting angle into account. The modified edge load (MEL) is calculated according to Formula (5). (5) w
48、here MEL modified edge load J/m bar width mm groove width mm cutting angle ISO 2013 All rights reserved 5 ISO/TR 11371:2013(E) 3.4.4 C-factor theory The C-factor theory developed by Kerekes (see Reference 5) is probably the most comprehensive one to date. As for other theories, it is based on the assumption that the specific refining energy can directly be related to the number of impacts and to the intensity of each impact, see Formula (6). (6) where E specific refining energy N number of impacts l specific energy/impact The C-factor repre
