Paper Technology Journal - Voith

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The author: Harald Selder, Stock Preparation Division News FROM Stock THE Preparation DIVISIONS Stock Preparation Division: New process technology for high quality deinked pulp Following comprehensive trials carried out in the pilot plant of the Voith Sulzer Stock Preparation Division in Ravensburg, Germany, UK Paper, a paper mill located in Kemsley, Great Britain, and belonging to the Fletcher Challenge Group, placed an order for the supply of a turn-key deinking plant for the preparation of recovered mixed office papers. The following is a report on the process installed at Kemsley. The report comprises the following sections: ■ Procedure in developing the system ■ Pilot plant trials ■ Project realization based on the results of the pilot plant trials. Procedure in developing the system Factors influencing the design of the plant Fig. 1 shows the factors of particular importance to the customer in designing his deinking plant. The two most impor- Chemicals Energy Finished stock requirements Plant design Control, instrument. and personnel costs 5 tant factors are the type of raw materials and the requirements for the finished stock. Other factors are fresh water consumption, the amount of rejects material and personnel as well as control and instrumentation costs. Combining personnel and control and instrumentation costs into one block is because of the close relationship between these two parameters. Experience generally shows that where control and instrumentation costs are high, personnel costs can be reduced to a certain extent. The two most important parameters of influence, finished stock requirements and grade of raw material, are now dealt with in detail. Finished stock requirements In Central Europe, UK Paper is one of the leading manufacturers of high quality, wood-free business papers, including copy papers. This exacting production program thus automatically places great demands on the raw material. The following lists the most important optical, technological and colloidal-chemical criteria for enabling the use of deinked pulp in UK Paper’s products: Type of raw material Amount of rejects Water consumption 1
2 6 Fig. 1: Factors influencing the design of the plant. Fig. 2: Characterization of recovered mixed office papers (after pulping and coarse screening). ISO brightness without UV luminance [%] Dirt speck area [mm 2 /m 2 ] Stickies [mm 2 /kg] Ash (575°C) [%] 70 65 60 55 6000 4000 2000 0 4·10 4 3·10 4 2·10 4 1·10 4 0 30 20 10 0 2s 2s Mean 59.7 1 2 3 Trial 4 5 Mean 2827 1 2 3 Trial 4 5 1 2 3 Trial 4 5 2s 2s Mean 13,580 Mean 20.6 1 2 3 Trial 4 5 ■ Finished stock brightness 80-85% ISO without UV luminance ■ Cleanness ✜10 ppm ■ Stickies ✜150 mm 2 /kg ■ Ash ✜5% ■ Freeness 420-370 CSF ■ Low/constant cationic demand ■ Low COD value. With the exception of freeness, ash and stickies content, the requirements are roughly the same as for virgin fibres. Raw material Following comprehensive research and studies carried out by UK Paper, the decision was made to use recovered mixed office papers from the London area. This decision was made on the basis of price, quality and availability. Technological characterization of recovered mixed office papers 5 pilot trials, each with 3 tonnes of recovered mixed office papers from London and surrounding areas, were carried out in the pilot plant facility of Voith Sulzer’s Stock Preparation Division in Ravensburg. This enabled an optical and technological characterization of this raw material to be made. In view of the large amount of recovered paper processed during these trials, the characterization results can be taken as representative. These comprise the characteristics of brightness, cleanness (expressed as the dirt speck area), stickies and ash. The characterization results are shown in Fig. 2. As regards brightness, the recovered mixed office papers have an average ISO value of 59.7% (without UV luminance). The standard deviation here is ± 5% ISO points. The average cleanness, expressed as specific dirt speck area, is 2827 mm 2 /m 2 . The fluctuations in cleanness are ± 1600 mm 2 /m 2 . As for stickies, the average contamination is 13,580 mm 2 /kg, with the values showing a standard deviation of ±11,600 mm 2 /kg. These large fluctuations are typical for recovered mixed office papers, and can be attributed to the varying content of self-adhesive (pressure sensitive) envelopes. The average ash content of recovered mixed office papers is 20.6% ± 5%, based on an incineration temperature of 575°C. These average values must now be set against the requirements placed on the finished stock. From this comparison the required system efficiency as illustrated in Fig. 3 is derived. As regards ISO brightness (without UV luminance), an average absolute increase of 22.8% points is necessary. With stickies, the required reduction is 98.9%, while with ash it is 75.7%. The highest required system efficiency concerns stock cleanness, where the reduction is 99.65%. To achieve these objectives, the stock preparation technician can use the following system modules. The process modules have, as Fig. 4 shows, very specific ranges in efficiency. As far as the increase in brightness is concerned, the
Page 1 and 2: 6 Paper Technology Journal News fro
Page 3 and 4: 2 The managers of Voith Sulzer Papi
Page 5: 4 Do you remember? Three years ago
Page 9 and 10: 6 7 8 Fig. 6: Improvement in cleann
Page 11 and 12: 10 The author: Peter Christmas UK P
Page 13 and 14: 2 12 Fig. 2: Development in deinked
Page 15 and 16: 4 14 Fig. 4: Cost structure. Table
Page 17 and 18: 16 The author: Helmut Berger, Wepa
Page 19 and 20: 5 6 7 18 Fig. 5: Stickies area in t
Page 21 and 22: 10 20 Fig. 10: Reduction in dirt sp
Page 23 and 24: 22 The Eltmann mill of the Palm pap
Page 25 and 26: 24 With a considerable total invest
Page 27 and 28: 32 The author: Bernhard Kohl, Paper
Page 29 and 30: 5 34 Fig. 5: Web run from bottom to
Page 31 and 32: 36 The author: Harald Weigant, Andr
Page 33 and 34: 3 4 38 Fig. 3: Waste water processi
Page 35 and 36: 6 40 Fig. 6: The control room. is p
Page 37 and 38: 42 The Paper Machine Division Board
Page 39 and 40: 44 producers of board and packaging
Page 41 and 42: 46 The authors: Franz Kayser, Micha
Page 43 and 44: 48 Fig. 4: Comparison of the blacke
Page 45 and 46: 50 Since Production of winders 1995
Page 47 and 48: 6 52 Fig. 6: TORO TD for Stora Gryc
Page 49 and 50: 10 11 12 54 Fig.10: TORO SD. Fig. 1
Page 51 and 52: 56 The authors: Alessia Gasparutti,
Page 53 and 54: 3 58 Fig. 3: Forming roll covered w
Page 55 and 56: 60 Kirsten Kolvenbach in conversati
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62 Service Center Heidenheim Tel. +
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2 3 64 Voith Sulzer Paper Technolog
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International PAPER TECHNOLOGY 2 Ba
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■ Established constantly sustaine
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Since 1980 eucalyptus has played a
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Joseph Michel and Jacques Étienne
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76 could not decide whether or not
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2 Paper Technology Journal Newsmaga
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