FCBA and CTP at the 2009 ERGS seminar : exchange on mechanical pulping between experts

The Eminent Refiner Groundwood Scientists (ERGS) Association gathers 40 main scientists in the world working in the area of mechanical pulping and pulps.
The idea of creating such an association was launched in 1976 in Canada by Douglas Atack and Don May of Paprican (now FP Innovation), Alkis Karnis of Domtar Research, Mike Jackson of MacMillan Bloedel, Jan Hill of STFI (now Inventia), David Wild of Domtar and Ray Leask of Ontario Paper (more information in the attached document).

The emblem of the association is a northbound large-eared African elephant, Loxodonta Africana, for the following reasons:

• Loxodonta Africana is difficult, almost impossible to tame, showing a very strong self will,
• If training does succeed in taming the beast, the elephant and his keeper will become inseparable, working together in many case for the rest of their life,
• Elephants like very much to perform circuses,
• The elephant never forgets,
• Elephants become dangerous when aroused. Old bull elephants may become unruly and eventually deranged and in the wild, often become solitary outcasts from the herd,
• The female elephant however is usually placid.

A seminar is organised every two years in connexion with the International Mechanical Pulping conference.
Michel Petit-Conil, New Materials division Director at FCBA and Process-Pulps & Functional fibres Group Manager at CTP is a Regular Member of this association. Michael Lecourt, Project leader and expert in mechanical pulping at FCBA’s New Materials division was invited to this seminar to present a part of his recent work in mechanical pulping (results for the FCBA Orichip Project).

This year, the seminar was held in the Swedish ski resort of Åre at the end of May. 48 attendees from 9 countries participated to this seminar.

Presentations were given in the following sessions:

• Session 1: Energy consumption and effect on green house gas generation
• Session 2: Papermaking and Productivity & Quality
• Session 3: New and old raw materials – Future research needs and initiatives
• Session 4: International research focus

Presentations were given in each session and the main information is given as follows:

• The carbon footprint of P&B products
  (H. Muenster)
  
  It is now a new item. Ten elements to take into consideration: carbon sequestration in forests, carbon stored in forest products, GHG emissions from forest products manufacturing facilities, GHG emissions associated with producing fibre, with producing other raw materials/fuels and with purchased electricity, steam, heat, hot air and cold water, transport related GHC emissions, emissions associated with product use, with product end of life, avoided emissions and offsets. The carbon footprint of TMP produced at 2000 KWh/T can be between 0 and 1680 CO2/t, depending on the method of power generation. A reputed database indicates 397 kg CO2/t for market mechanical pulps and 320 for market NBSK.
  
  One tone of wood equals 500 kg carbon, i.e. 1833 kg CO2. If the product life is long (>100 years), carbon is removed the atmosphere. In mechanical pulping, the pulping yield must be considered and the way how the energy is produced. At the gate of a papermill, 1155, 766, 834 kg CO2/t for TMP, NBSK (non integrated), DIP, i.e. 920 for the paper (33/33/33% of each pulp). It is high value of burning lignin in the boiler to generate the energy. If the wood quantity is considered, 418, 766, 0 kg CO2/t for TMP, NBSK, DIP is obtained, i.e. 29 for paper sheet. If the wood is considered in building products, 1155, 766, 834 kg CO2/t for TMP, NBSK, DIP. The carbon footprint increases with specific energy in TMP production.
  
  
  
• LCA of magazine PM – Effect of different process & energy options to carbon footprint
  (K. Behm, KCL)
  
  Results from the European EcoTarget project.
  
  Focus in the changes in the magazine paper mill. Use of standards SFS-EN ISO 14040 and 14044. Integration of low-energy for mechanical pulping (20% energy savings). Indicators: wood, chemicals, energy, water, products, … Consideration: Swedish mill, Swedish energy and heat production profile, fluidised bed boiler and steam turbine for the energy produced at the mill. Consideration of chemicals, energy production, paper production, pulp production, sawmill, transport and wood harvesting in the simplified flowsheet of LWC system. Very favourable corresponds to >15% changes. If oil is considered as auxiliary fuel, increase in air emission (CO2, NOx, SO2), lower heat produced at TMP but less electricity purchased and less wastes. It is not as a good change for a 20% TMP energy reduction. The increase in CO2 is 1.3% in Europe with this new technology. If wood residues are considered as auxiliary fuel, less air emissions (CO2, SO2). For the carbon footprint (1 kg CH4= 25 kg CO2 eq, 1 kg N2O=298 kg CO2 eq), the new technology in LWC production decreases the carbon footprint. Consequences of decreasing energy in TMP depend on auxiliary fuel.
  
  
  
• Forest as a resource – Most important profile area of Mid Sweden University/FSCN and research program on an energy combination with mechanical pulp based product as a core
  (P. Engstrand, Mid Sweden University)
  
  Pulp and paper industry is capable of producing products of very high value, with high raw material yields, where the product is recycled, based on green chemicals, of production of large energy production. The objective is to develop a concept of mechanical pulping based industry combine that is sustainable from all possible angles, create new products of high economic values (chemicals, fibre based products and energy), minimise the negative effects. It is the concept of biorefinery adapted to mechanical pulping. Gasification of mechanical pulping wastes in combination with forest residues to produce hot water and electricity. In Sweden, very high demands in sustainable methods and environmental issues. Different projects are under progress: new chemicals from mechanical pulping process, energy efficient refining methods, gasification of forest and process reject biomass, fractionation and stratified forming, sustainable forest production, integrated systems analysis, new fibrebased products, paper chemistry in mechanical pulp based production systems (Presentation commerciale).
  
  
  
• Industrial possibilities of bio-refineries with mechanical pulping by-products
  (C. Sandberg, Holmen Paper)
  
  How about refiners and grinders if electronics replace paper ? We need to be innovative.
  Biorefinery in Google: 170000 hits. Biorefinery + mechanical pulping: 500 hits. An area of interest. Two examples:
  In connexion with the Braviken, papermill, paper will become a by-product for the mill if we consider the production of electricity, flue gas, pellets, bio-gas and sawn wood. This will become a reality very soon. There are potentials to save energy and to have good energy balance. Consideration of low-energy TMP but with less steam, larger boiler (bio-fuels) to produce more green electricity.
  Interests in bark: flovonoids, lignans,… Acid hydrolysis pre-treatment with removal of hemicelluloses, which could become value-added products. New TMP line with MSD system followed by double disc refiner and roll press. At the output of MSD and roll press, there are chemicals that could be recovered from these effluents. Use of fibres in bio-composites: potential for the mill of 700 000 tons, especially in car components. New potential products: food packaging to replace plastics, replace cotton fibres. Plastics represent 36% in packaging versus 42% for paper.
  
  
  
• “Semper metam contingimus” – From one stone to a mountain
  (O. Ferritsius, Metso)
  
  To find the maximum of energy efficiency in processes. In the last IMPC, 55% of the papers deal with energy-freeness = mechanical pulp, which can be simplified in E=mc² (!!). 5 fundamental properties for TMP: shives, colour, length, bonding and resin. Communication must be taken into consideration. Pulp is produced from wood chips through the refiners. We have to consider the production of individual fibres with a specific distribution. Depending on the refiner system, the fibre distribution is different, giving a fingerprint of the process. Bonding indicator is directly correlated to tensile index. The consideration of fibres in wood and after processing is of importance. Future process: double disc refiner in first stage, fractionation/screening and post-refiner (counter-rotating refiner) to maintain the same fingerprint to the pulp produced. We can apply high amount of energy to produce flexible fibrillated fibres without changing the pulp fingerprint. This will increase the energy efficiency. There is a good relationship between wideness and bonding indicator: the higher the wideness, the higher the bonding indicator. The pulp producer must become a fibre designer (Présentation phylosophique et fondamentale).
  
  
  
• Modern process optimisation for maximised productivity and quality at the papermachine
  (J.P. Bousquet, Metso)
  
  The main objectives of mechanical pulp producers are to reduce capital and operating costs achieved by maximising the production rate, decrease the number of equipment in a process line, reduce the specific energy consumption and increase yield. Softwood TMP driven by cost and quality: minimise the number of HC refiners, use of LC reject refining if the reject rate is lower than 10%, LC refining in a single stage with 90 kWh/t, small hole screening. Hardwood BCTMP driven by cost: reduce the amount of equipment and process steps, increase the use of LC refining if the recovery of chemicals is not critical.
  
  There are now solutions to reduce energy consumption: reduce operating process disturbances with advanced control systems, refiner segment development, operation at higher production rates, use of LC refining at different stages of the process. Other conditions/technologies claiming decreasing energy are not ready. For LC refining, to replace a HC refining and to reach a given freeness, several LC (3.5%) refining stages are needed, even if the energy consumption is decreased and the fibre cutting is also increased, especially in the low freeness range. No impact on shives generation. Lower tensile and tear indexes are obtained. For tear index, the decrease with freeness is less sensible. Same porosity and scattering coefficient.
  
  
  
• Impact of the water management in refiners on the TMP process
  (M. Lecourt, FCBA)
  
  Mechanical pulp production is based on the use of wood and electricity. A third relevant factor is water introduced in pulping process: it will impact on fibre separation mechanisms and as a consequence on pulp quality and energy consumption. This work focused on water introduced into refiners. Indeed, water could be either: dilution water injected between refiner plates, or wood water. Moreover, it could be free water, located in lumens or water bonded to cellulose or hemicelluloses, located through the fibre walls.
  
  Thus, various tests were performed on a 12” pressurized pilot refiner in order to determine how water could impact on refining process and pulp quality, depending on its origin.
  Firstly, nine different conditions were considered during defibering stage. Norway spruce chips were fresh, immerged in water or dried. This resulted in 3 different dry matter contents. Meanwhile, three dilution water flows were considered. Results on defiberised pulps were rather similar in terms of fibre and shive morphology. Higher energy consumption was measured at low water content conditions. Then, pulps were refined in similar ways. Dilution water flow impacted energy consumption balance between first and second stages: the more the dilution water flow in the 1st stage, the worst defiberised the fibres and the more the energy needed during refining to reach a given freeness. As a consequence, it resulted in more shives, shorter fibres and finally a lower tear index. Dilution water flow was the parameter of most importance as it changed pulp rheology and behaviour in the plate gap. Chip dry matter content led to more limited changes.
  
  Secondly, a given defiberised pulp was refined under pressure at various consistencies. Some water was added in order to reach three dry matter contents. During refining, dilution water flows were given 3 different values. As a consequence, 9 different conditions were tested.
  
  Origin of water did not present any impact on pulp properties. Relative consistency in refiner casing was the only parameter of importance. The more the water content and the more the cutting phenomena. It was attributed to more fibre to bar contacts. Meanwhile, fibre bonding potential was better-developed and tensile index improved.
  
  
  
• Study of the energy balances and flow conditions in blow lines in two-stage mill scale refiner line
  (T. Tienvieri, UPM)
  
  The paper is available in the IMPC proceedings.
  
  Flow rate is measured by using a radioactive tracer. Pulp in 1st stage refiner blow line is 8 m/s whereas in the 2nd stage, it is 27 m/s. The share of recovery steam heat power of the refiner power is 80% by calculation, whereas the mill indicates 75-77%, i.e. reliable measurements. The steam flow speed is quite low in the blow line of the 1st refiner. With the radioactive tracer into the fibres, the pulp flow is measured at 3 m/s. The share of wet fibres flow is only 1%. If the blow line flow speed at 8 m/s is so low that capacity increase is possible. This low speed maintains a good cleanliness of the blow line. Some condensation occurs, cleaning also the pipe.
  
  
  
• Future prospects of mechanical pulping
  (A. Vehniäinen, UPM)
  
  Work carried out during its former position at KCL. AV is now working on nanocellulose at UPM. A lot of work has been done to decrease the energy consumption for the same pulp quality since the 80’s. It is important to understand better the fibres. If fibres are considered, pay attention at enzymatic treatment , chemical treatment on the fibre properties. Modifying grinding surface allows to reach the same tensile at 30% less energy. Fibre properties, such as fibre cutting, fibre wall reduction, are important to act on defibration action and effects. Several concepts to reduce specific energy consumption are ready for use. For significant energy savings, development of new pulp types and furnishes with altered properties is needed. The 70-85% yield range must be revisited, in associating biorefinery, new fibre products and new techniques. It is not possible to stop to work in energy savings in mechanical pulping, but this energy must be used in an efficient way.
  
  
  
• Summary of the international mechanical pulping development in connection to future research needs
  (J. Hill, Norske Skog)
  
  In 1980, wood cost dominates the production costs. In 2006, equal consideration for wood and energy costs. Norske Skog has 7 spruce TMP mills, 5 pine TMP mills and 4 DIP all over the world. Need for mechanical pulps and recycled fibres in Europe in 2007 to 2020, 50 to 70 and 14 to 20 millions tons, respectively. Stability for total virgin pulps. Which fibre to be used for what, in a maximised value creation. Today, wood and energy represent 50% of the newsprint cost structure. In the future, they will represent almost 75%.
  
  Fibre separation needs less than 250 kWh/t but fibre development for publication papers is higher than 1500 kWh/t. The challenge is to use energy appropriately for process and to select the fibre fractions to be used. Return on electrical energy reductions in 2 years: at 75 €/MWh, 6 M€ for 10% savings, 12 M€ for 20% and up to 18 m€ at 30%. The higher the electricity cost, the higher the return.
  
  For process design, development has been frozen by the traditions of big consultants. The challenge is to improve the competence level of all involved. Add new steps in the process is favoured on redesign the process. Project started Energy efficient mechanical pulp research initiative (E2M?)started 2 years ago (Holmen, UPM, Stora Enso, Norske Skog): BAT approach directed towards energy optimisation, operational strategies on aggressive fibre developments, increased bleaching competence, system closure and quality of white waters, impact of polymer character of fibres and its implication on energy demand, CTMP, fibre flow in steam phase.
  
  
  
  Asis’s growing demand for paper & board products. New challenges to mechanical pulping?
  (E. Viljakainen, Asian Institute of technology, Pulp and Paper Technology)
  
  Presentation of AIT: 50 years old. Plantations of eucalyptus trees, cropped every 4 years. This wood will be used for pulp and paper production and for energy and heat. About a quarter of global recovered papers is captured by Asian countries.
  Characterisation of the specialty pulp from leaf fibres (sisal and abaca). Very high cellulose content and very low lignin content. No silica problem in such fibres. For abaca leaf fibres, L/D is 300:1 and for sisal leaf fibre 180:1, compared to 100:1 for softwood fibres. To reduce GHG, energy should be based on renewable energy sources (bio-material, wood waste, nonwood residue/waste). In Asia, to reduce GHG, loca raw materials should be favoured and used for specific products. Mechanical pulping must be considered from these raw materials.
  
  
  
• An outlook of the future mechanical pulp capacity and research need development in China
  (G. Fang, Pulp and Paper R&D Center, Chinese academy of Forestry)
  
  China has become the first pulp and paper producer in 2008 with 84 million tons, higher than in the USA. The raw materials used for the mechanical pulp production are fast-growing wood, residues, chip mixtures from poplar (77%), eucalyptus (18%) and pine/fir. Utilisation de la pâte mécanique pour journal, magazine principalement (présentation très générale).
  Mechanical pulping from nonwood is growing but application limited to board.
  
  
  
• Welcome to China for the 2011 IMPC
  (Y Ge & M. Zhang, Department of International cooperation and exchange, Chinese Academy of Forestry & Shaanxi University of Science and Technology)
  
  China is the biggest market for pulp and paper industry. Mechanical pulping is a big challenge due to environmental regulations in China. Chinese Academy of Forestry is collaborating with US2B (Bordeaux). Proposition to organise the next IMPC at Xian where important pulp and paper facilities and universities are located.

An official dinner closed the seminar during which new ERGS members were elected after an official vote and an humoristic speech.