News
The 24th Leask Survey:

Tough times continue to haunt Andritz and Metso Paper (Metso Paper is the new name for Valmet, previously, the old Sunds Defibrator), the two remaining manufacturers of mechanical pulp refining equipm…

Tough times continue to haunt Andritz and Metso Paper (Metso Paper is the new name for Valmet, previously, the old Sunds Defibrator), the two remaining manufacturers of mechanical pulp refining equipment. Over the past three years, less than 1500 tonnes per day (t/d) of design tonnage have been sold annually. However, there is a glimmer of hope for better times ahead. Sales of mechanical pulping are showing an improvement for the first two months of 2001.

This year’s survey covers the years 1998, 1999 and 2000 as well as the first two months of 2001. The sales for 2001 are not included in the annual tonnages, but are shown to indicate the upward trend for the coming year.

The replies for the survey showed a purchase in 1998 of nine high consistency refiners by five mills situated in China, Sweden, France, Iran and Canada. Three low-consistency refiners are also included for reasons of process description. Details are included in Table I.

Sales for 1999 included 15 high-consistency refiners and two low-consistency refiners to six mills in the United Kingdom, Switzerland, Canada and Finland. See Table II for the details.

In 2000, there were 10 sales of high-consistency refiners for three mills in Iran, Finland and Sweden. Details are provided in Table III.

Finally, to indicate the possibility of a turn around, 2001 sales to date are included in Table IV. There were nine high-consistency refiners and one low-consistency refiner sold to six mills in China and Sweden.

These orders amounted to a design tonnage of 1187 adt/d in 1998, 1380 adt/d in 1999, and 967 adt/d in 2000. The total design capacity for TMP and associated high-yield mechanical pulping processes is now 112 359 adt/d or about 41 million adt/y. Figure 1 shows the cumulative production of refiner mechanical pulps from 1974 to the year 2000. The year-to-year change in tonnage is illustrated in Fig. 2. These increases are the lowest consecutive increases recorded since the survey was started.

I must interject a word of caution about the daily production figures. As can be seen in the tables, a number of refiners are replacing existing older refiners and, while I have tried to capture the incremental change in capacity, this is not possible in all cases. The other area of possible inaccuracy is accounting for the shutdown of existing mechanical pulping equipment for a variety of reasons. For example, I know of two mills that have reduced TMP production, replacing it with increased use of deinked pulp. These mills will totally stop production of TMP in the future and use a 100% deinked pulp furnish. However, these decreases in daily tonnage are offset by the ability of operators to push production above design without purchasing new refiners. One mill I was involved with has taken a plant designed for 660 adt/d to over 800 adt/d with minor equipment changes and then obtained a further increase in production to over 900 adt/d by the addition of three low-consistency refiners.

Nevertheless, there are some interesting trends. The size of refiners has increased with motors up to 32 MW now being used on Metso Paper refiners and up to 28 MW on Andritz refiners. Energy reduction is a priority as shown by the installation of Andritz’s RTS process and Metso Paper’s Thermopulp process at a number of mills. The use of third-stage refining either at high- consistency or low-consistency is common. This is done for a number of reasons. First, greater tonnage can be made on a single line of refiners, which is less expensive than adding another line when a comparatively small amount of extra tonnage is needed. Second is pulp quality. Fibre cutting, often a problem in second-stage refiners, can be reduced or eliminated by using a third-stage refiner to apply more energy to the pulp. Finally, low-consistency refining allows either incremental capacity or an increase in pulp quality for lower energy expenditure.

Metso Paper reported the sale of 10 new PGW grinders, Table V. Additionally, mills are installing improvements and upgrades especially the Water Jet Stone Conditioning System. Nearly 130 grinders are now equipped with this system. The Water Jet System uses 36 000-psi water to efficiently clean the pulp stone surface, eliminating or reducing the need for sharpening with a steel burr.

New developments

Andritz Inc.: Andritz continues to conduct research and development activities related to low-energy refining. The development of high-intensity process configurations, which combine high disc speeds in both refining stages (RTS2) with new refiner plate geometries, is an ongoing effort to reduce the energy consumption of pressurized refining to comparable levels with groundwood processes. Andritz’s chip conditioning system described in the 23rd Annual Leask Survey has been demonstrated in a commercial installation. The resulting pulp had higher tear and was lower in COD, pitch chemicals and anionic carryover for the pine furnish. Development of “direct blow” technology from the primary refiner to the secondary refiner feed has permitted increased levels of fibre heating (i.e., higher pressure) in the secondary refiner. The lower retention times at system pressure allow the pulp to retain good optical properties at elevated pressures. The low-energy/high-consistency refining processes have also been combined with improved mainline low-consistency refining (LCR) technology to further minimize energy consumption requirements. Andritz also conducts research and development activities related to chemimechanical pulping systems for softwood and hardwood species.

Metso Paper: Development in TMP continues to focus on reducing capital and operating costs through increased capacity and reduced specific energy consumption from larger refiners. The large RGP 82 CD refiner is now proven at 32 MW, Table I, with an excess of 770 adt/d of newsprint quality TMP pulp being produced in a single line of refiners. The improvements in refining efficiency due to these increased pulping capacities result in energy savings as does low-consistency refining in third-stage refiners. New refiner segment design has also helped reduce energy use in recent years. A number of mills are operating exclusively with low energy segments.

Groundwood research is also continuing at Metso Paper. A new pressure grinder is under development; log batches are fed into the side of the grinder pocket. Continuous grinder loading is also being studied at the pilot scale. It is expected that a continuous feed grinder will have a production capacity that will be 60 to 70% higher than today’s highest capacity grinders.

Research institutes

The consolidation in the pulp and paper industry has not just affected the paper companies and vendors but also the research institutes. However, the research institutes have maintained a dynamic range of work and are using joint ventures for major undertakings.

Centre Technique du Papier (CTP) France: The high-yield pulping research group is undertaking a number of interesting projects. The effect of changing the lignin content of poplar trees by genetic modification was found to have a direct effect on pulping behaviour and pulp quality. The use of ozone in the eye of the refiner to enhance accessibility to the fibres is being evaluated in terms of energy consumption and pulp quality. New possibilities in high-yield mechanical pulp bleaching are being tested based on bleaching techniques developed for chemical pulps. Mechanical pulp fibres from different TMP processes were characterized in terms of fibre dimensions and morphological characteristics (fibrillation, relative bonded area, fibre distribution, etc). Finally, a screening modelling project is in progress. Different screening conditions (rotor type, basket, etc) are being compared and studied.

The Finnish Pulp and Paper Research Institute (KCL) and the Swedish Pulp and Paper Research Institute (STFI): KCL and STFI have joined forces for a three-year mechanical pulp research program (2000 – 2002). Eka Chemicals, Holmen, Metsliitto-Group, Myllykoski, Stor
a Enso and UPM-Kymmene finance the program. The program, which at this point includes 11 joint projects, focuses on two major areas:

Mechanical pulping processes with minimum energy consumption;

Utilizing the complex nature of mechanical pulp for optimal cost performance.

Although the know-how generated is restricted to the six financing companies, other companies will benefit from the joint program, as the program develops further ways to use the pilot plant and testing facilities at both institutes. Thus, it will be easier to use pilot equipment at both institutes for the same contract work: TMP and screening at KCL and the FEX paper machine at STFI. Also, the program is developing fibre testing methods, with the objective to simplify today’s varying techniques used for testing fibre properties.

Institute of Paper Science and Technology (IPST): There are two on-going high yield projects at IPST. One is an effort to develop technologies for photo stabilizing high yield pulps. Recent studies have shown that a mild acetylation can enhance the photo bleaching properties of mechanical pulps when they are irradiated with office light. The research is directed towards exploring the fundamental chemical processes involved in photo bleaching CTMP.

The second effort is to develop a bond area measurement based on the well-established Ignamson and Thode wet-pressing procedure for chemical pulps. The key technology that makes the technique possible is the use of hot platens in the pressing procedure. Current efforts are directed towards understanding the role of fines in the bonded area measurement and eliminating error from fines and fibrils bonding to fibres in a manner that does not enhance interfibre bonding.

New Zealand Forest Research Institute – PAPRO Division: PAPRO is continuing to expand its international business through the provision of improved processing strategies to industry.

Concepts may be tested in refining and screening trials performed in PAPRO’s Fiber Processing Plant. Within its research program, new pulping and screening concepts are being evaluated. Concurrently, there is an increasing emphasis on the understanding of the role of fibre quality in developing superior paper and print quality. Both research areas are integrated within the wider molecular biology, materials knowledge and supply chain management programs of PAPRO’s parent organization. This integration allows both (a) improved process concepts to be derived from a knowledge of fundamental fibre behaviour and (b) optimal fibre to be genetically selected and grown from a knowledge of the requirements of the paper.

Pulp and Paper Research Institute of Canada (Paprican): Paprican’s mechanical pulping research can be divided into several areas including: novel methods of pulp production, bleaching, yellowing inhibition, fractionation and the interaction between pulp and fibre characteristics and paper properties. The yellowing inhibition technology moved a step closer to commercial implementation with the successful execution of a mill-scale trial in partnership with Ciba Specialty Chemicals. Mechanical pulping capabilities are being expanded with the start-up of two new pilot plants in early 2001. Andritz has supplied a TMP pilot plant, which consists of a 22-in. diameter pressurized refiner with an impregnation screw for chemical treatment. The fractionation pilot plant will employ the latest advances in screening and cleaning technology. Combined with existing equipment, Paprican has the capability to go from logs or chips to pulp to finished paper on its new pilot paper machine. This will allow both member companies and other clients to explore the potential of new pulping and fractionation technologies in value-added mechanical printing grades by measuring not only pulp and fibre characteristics but also final paper properties.

Adrian Barnet, Abitibi-Consolidated, is now project manager, Groundwood Improvement Project, Lufkin, TX.

Table I. Refiner orders 1998

TABLE II. Refiner orders 1999

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TABLE III. Refiner orders 2000

TABLE IV. Refiner orders 2001 (January & February)

– Number of refiners

– Power MW/ refiner

TABLE V. Grinder orders