ESTIVALE 99: answers questions, shows technical innovations
August 1, 1999 By Pulp & Paper Canada
Where is R&D going in these times of consolidation? Is the pulp and paper industry ready to answer the demands of the third millenium? Do you get your money’s worth out of your DCS? These questions, a…
Where is R&D going in these times of consolidation? Is the pulp and paper industry ready to answer the demands of the third millenium? Do you get your money’s worth out of your DCS? These questions, and more, were asked and, in most cases, answered during the 21st edition of the Estivale Technological Conference held once again in Quebec City’s, June 2 to 4.
Attendance was unexpectedly high at this year’s conference, which featured three roundtables, three technical sessions and two training sessions which opened the program on June 2. Interestingly enough, the Raimbault Demontigny prize for the best technical presentation was awarded to two papers. In fact, the judges (Louis Sabourin, Kruger Inc., Claude Daneault, Universit du Qubec Trois-Rivires [UQTR]; and Pierre Bellerose, Hercules Canada) thought at least four papers deserved to be rewarded. “In these depressed times, there is definitely something to be said about salvation of our industry through innovation. We had great innovation examples during this conference,” Sabourin remarked.
Jean-Noel Cloutier and Michael Paleologou, Paprican, shared the Raimbault Demontigny with Rmy Simard, Daishowa. Simard discussed how to better control residual inks in deinked pulp with a sensor tailored to Daishowa’s needs. Two important parameters are carefully monitored at Daishowa to ensure high pulp quality in the deinking mill: brightness and residual ink (ERIC 950). Both are measured off-line with the Technibrite Colorimeter following standard methods and also on-line with three brightness sensors (flotation feed, flotation accept and final pulp).
Internal studies proved that the residual ink has negative impact on sodium hydrosulphite consumption. When residual ink increases, the TMP has to be overbleached to compensate for lower paper brightness. This is why the authors were interested in an on-line residual ink measurement to identify sources of variation (recycle paper quality, operation parameter). “In addition, we knew that an on-line residual ink measurement sensor would be very useful to follow the quality of our deinked pulp operation, as well as to optimize the overall operations,” Simard said.
Since no such sensor was available on the market, Daishowa and BTG worked together on developing an on-line sensor capable of measuring residual ink continuously. The research paid off because a mathematical model was developed using the optical readings of the existing sensor and data from the lab. Continuous on-line readings are now done with precision.
Selective Recuperation of Essential Chemical Products in a Kraft Mill was also awarded the Raimbault Demontigny prize. The paper was presented by Jean-Noel Cloutier, who reminded the audience that chemicals such as sodium sulphate, sodium hydroxide, sulphuric acid and oxygen are essential to the operation of bleached kraft pulp mills while the presence of sodium chloride is undesirable. Two new technologies for the recovery of these chemicals have been recently developed at Paprican and are now available for commercialization.
Sodium chloride, which accumulates in the electrostatic precipitator dust of the recovery boiler, can be removed by selectively adsorbing it onto a resin bed, which excludes sodium sulphate and carbonate. The chloride-free sodium sulphate and carbonate can then be converted into sodium hydroxide, sulphuric acid, oxygen and hydrogen by using electrolysis, a membrane-based electrochemical process. These two technologies not only allow mills to improve the control of their chemical balances, but can also be integrated to existing chemical recovery systems.
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The 18 technical papers presented were grouped in three sessions: Papermaking, Pulping and Environment. Paprican researchers prepared one-third of the papers presented, a testament to the key role of the Institute in the pulp and paper industry and in R&D.
At the Papermaking session Thursday morning, Jean Hamel, Paprican, shared the results of a study on run-ahead. This is a problem that occurs with printing presses when the web in contact with the metallic band decelerates faster than the roll or when the web stops completely but the roll continues to rotate. This leads to a bubble or bunching of paper layers on the ingoing side of the bands which will break the web.
A model was developed to characterize run-ahead which accounts for press operating conditions, and paper and roll properties. According to the model, run-ahead depends on the following press parameters: wrap angle, deceleration rate and unwinding tension.
How can this problem be reduced? Different “recipes” are proposed: increasing the wrap angle between the braking band and the paper roll, reducing the rate of deceleration, reducing the web tension on the press and/or increasing the wound-in tension. The key factors to consider are the static, paper to paper coefficient of friction and the dynamic coefficient of friction between the paper and the band material.
It was then on to press rolls as C.B. Thompson, Paprican, discussed surface roll characterization using microscopy. Knowledge of the surface condition of press rolls is important for efficient paper machine operation. Thompson and his team have developed a quick and easy technique for taking precision replicas of roll surfaces. These can then be examined in the laboratory using optical or electron microscopy. The technique has been used on granite and ceramic-coated press rolls. Replicas give unique insights into the nature and behavior of press roll surfaces that would otherwise appear similar in terms of touch, visual appearance or surface roughness. For example, an extensive network of pits, pores and depressions that lie below the doctored surface, characterizes ceramic-coated press roll surfaces. These features form convenient sites for the accumulation of pitch, stickies, and fibre debris, and account for the industry’s perception that ceramic rolls are harder to clean than granite rolls.
Another paper that caught the delegates’ attention was a feasibility study using asbestos in paper, presented by Sylvain Duquette, CSPP, Trois-Rivires. The development of papers fabricated with an asbestos basis has been done with the objective of producing a product that is heat, light, moisture and time-proof. One of the advantages of these papers made with an asbestos base is that, if burned, the information printed on it remains readable. Research on the subject is leading to the production of different papers. Efforts are being concentrated on the production of a permanent paper meeting international standards both in toughness and conservation. Trials have been done to produce a paper with a higher basis weight for artistic use.
Other papers presented at that session were: Control strategies at the wet end of paper machines, presented by Richard Proulx of BTG; The construction of a twin-wire forming device at McGill University to study both retention and drainage, presented by Christopher Hammock, Paprican; and TSO-TSI profiles: Tools to evaluate paper machine performance and paper quality, by Michel Gratton, Abitibi-Consolidated.
Subjects discussed at the Pulping session also covered a wide area of subjects, from deinking to chip freshness control. In fact, Abitibi-Consolidated, Belgo Division, equipped its wood receiving area with a new device which measures wood chip brightness. Stphane Deshaies, from the Belgo Division, explained that the mill established relationships between the brightness of the chips and their quality, thereby building a way to classify the chips depending on their anticipated yield.
With this new tool, installed on a parallel conveyor to the one bringing the chips into the pulping process, the mill was able to improve its control on raw material used for newsprint production. “With the results, we can qualify the chips, based on numerical data, ” Deshaies specified. “We can control the level of bleaching agents required; we can optimize the chips blend to obtain different levels of quality; and we will classify the chips according to wood q
uality and essence.” Belgo was even able to reduce its production cost, while reducing variability of the final product quality.
Other than the winning paper from Rmy Simard, two papers dealt with deinking. According to Gilles Dorris and Yuxia Ben, Paprican, ink redeposition during repulping may be a contributing factor to pulp darkening during deinking of water-based inks and aged inks. The severity of this redeposition problem was established with a model system consisting of virgin TMP pulp and a commercial water-based ink. After mixing both, a hyperwashing treatment was used to determine the amount of ink bound to long fibres.
The team found that a change in concentration of calcium, fatty acid, mineral oil and ink binder had a negligible effect on ink redeposition. On the other hand, increasing pulp consistency, repulping and storage times, rotor speed, power input and ink concentration all increased the concentration of redeposited ink particles. Dispersed ink particles and small aggregates in the pulp were found to adsorb predominantly on the surface of the fibre lumen.
A paper presented at the same session examined the effect on pulp characteristics of an extraction of pretreated Jack pine chips prior to a two-stage alkaline peroxide thermomechanical process. It was presented by Robert Lanouette, UQTR, in cooperation with Jacques L. Valade and K.N. Law, also from UQTR. Another study, presented by Sophie Veilleux, from Bowater Gatineau, measured macro stickies and optimizing the deinking process for old papers. One paper looked at the experience of Abitibi-Consolidated, Alma, QC with Statistical Process Control (SPC).
Friday morning’s session on environment featured its share of innovative research. Besides Jean-Noel Cloutier’s winning paper, the judges were very interested by a plasma-assisted sludge oxidation process (PASO) which was developed at the Hydro-Quebec Laboratory of Electrochemical and Electrical Technologies (LTEE) for the treatment of conventional press sludge containing at least 20% organic material.
The organic material is destroyed continuously in the presence of air at atmospheric pressure and at a moderate temperature of 600C to produce dry, sterile and odorless ashes that have potential value. The process presented by Claude B. Laflamme, Raynald Labrecque and Jean-Paul Bernier of LTEE, confines the oxidation energy to evaporate water and to heat gases, resulting in an electrical consumption below 100 kwh per tonne of humid sludge. The key element is the use of a low power plasma torch that catalyses the oxidation reactions, otherwise difficult to obtain at such temperatures and sludge humidity. The cost of a 400 kw installation capable of treating 100 t/d of sludge, is valued at $840 000. A payback of two years is possible when compared to a composting system/solution.
Daniel Turcotte, Papier Masson, described the integrated, single-window management system for hazardous material now in place at the mill. The system has enabled the mill to comply in a simple and constant manner with standards and legislation such as the Workplace Hazardous Material Information System (WHMIS). The system also ensures better risk management and prompt attention to the health and safety of workers.
David Durham, Daishowa Quebec, discussed the sludge pressing problems encountered at that mill (and in many others). The Quebec Forest Industries Association, in partnership with the CRIQ (Quebec Industrial Research Center) and Daishowa developed and evaluated a new 24-in. sludge press prototype which can operate at low ratios of primary sludge. The sludge press produced a sludge at 30% dryness using a mix of 55% primary sludges and 45% secondary sludges. And it was determined that the mill could gain another 2% dryness by using a 48″ sludge press.
Other issues examined at this session were the
— Environmental benefits from modifications to treatment and production processes in the P&P industry during the 1990’s, by Pierre Martel, Tibor Kovacs, Brian O’Connor, Sharon Gibbons and Ron Voss, Paprican; and
— the successful odor management program, now in place at James Maclaren Industries, Thurso, QC, by Christian Ledoux, James Maclaren Industries.
Participants discussed applied research versus “pure” research and suppliers’ R&D versus institutional R&D such as Paprican. One amusing comment was made by Donald Cayouette, vice-president at Kruger Inc., who said “Paprican is like an all-you-can-eat buffet: you pay $8.95, but whether you eat for $2.95 or $16.95 is really up to you.”
The roundtable on The future of paper presented an opportunity to expose a problem that paper mills are trying to avoid but which is very real: low quality. Pierre Rioux, vice-president, Imprimerie Quebecor, emphasized that the quality of paper produced is too low and cannot follow higher quality expectations from printers’ clients. “Their ever increasing demands in high quality printing paper is not met by the mills right now,” he repeated. “We have to compensate with very high quality inks and dyes.”
Patrice Mangin, director of the CTP in Grenoble, France, also gave his view on the future of paper. He said that Canadian fibre is not an advantage anymore, at least not in Europe. Other countries are producing an excellent quality of paper with lower quality fibre. He also said that the biggest challenge for the industry as a whole is to reduce the continuous improvement and production processes to the lowest cost possible.
As for the roundtable on DCS, it appears mill users do not feel they are getting their money’s worth. “When paying for a DCS system, you feel like you are getting a Cadillac but in fact we are getting the performance of a Volkswagen,” joked Stephane Rousseau, vice-president, production St. Laurent Paperboard. Other complaints: mills have to update the whole software when in fact they only use 2% of its functions. Users depend on third parties (suppliers) to update their DCS. Learning a DCS system is a never-ending process since changes happen all the time; and some systems are still not user friendly and are difficult to learn. Nonetheless, speakers and participants agreed that the cost of non-quality (going without a DCS) is far greater than living with those systems.
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