Research at Paprican focuses on retrofitting existing equipment for the best results
By Pulp & Paper Canada
PPC: Pulp and paper is a competitive business. What can be done to increase the speed and efficiency of the older machines in operation in Canada and to continuously improve product q...
By Pulp & Paper Canada
PPC: Pulp and paper is a competitive business. What can be done to increase the speed and efficiency of the older machines in operation in Canada and to continuously improve product quality?
Gauthier: New technologies and new concepts are required for the Canadian industry to remain competitive in the global marketplace. Paprican plays a major role when it comes to technology transfer and process optimization in the pulp and paper industry.
For example, in the past two years, on our pilot paper machine, we have completed trials for numerous clients. We have evaluated the performance of new equipment, tested new additives, production concepts, and products. These trials were performed for suppliers or for mills in collaboration with their suppliers.
PPC: Are there any particular trends in improving paper machines in the mills?
Gauthier: I don’t believe there are any trends but we do get special requests.
Paper formation is a big issue. At Paprican, we’re quite strong in this field and we do a lot of trials to optimize the formation.
We also get a lot of requests about fillers, from pulp and paper companies and from suppliers who are developing new products. Paper companies want to try or learn about the process. Some of the requests are about increasing the filler content in the sheet in order to reduce the fibre costs.
There’s some interest also in the press section as well but mainly in the forming section and the chemical additives.
PPC: Now in your answer you say that you are strong in the forming section. Why?
Gauthier: Because we have had a lot of projects in the forming section in the past few years and we are doing a lot of development. For two or three years now, we’ve been doing a project that is dealing with the low cost optimization of the forming section. We are still trying to develop completely new ways of forming.
We focus on trying to understand better the different elements we have in order to get the drainage in the forming section to improve. Our goal is to remove as much water as we can and also to get the best distribution of the fibres.
We have the collaboration of AstenJohnson on this project. JohnsonFoils, an AstenJohnson division, has some of their equipment installed on the machine. This equipment could be retrofitted into existing machines to bring it to the next generation. A mill desiring to evaluate the benefit of such a retrofit could come to Paprican and perform a trial on the pilot machine using their furnish and particular wet end chemistry.
PPC: Can you give us a specific example of a new process or concept that was tested on Paprican’s pilot machine and implemented in a Canadian mill?
Gauthier: There is a trend for papermakers to increase the filler content of the sheet to reduce the need for fibres and to improve the product quality. A new technology for increasing filler content, developed at Paprican and tested on our machine, is now used commercially. To be as representative as possible, we used the paper mill’s furnish and in some trials, even the whitewater was delivered from the mill. We refined the furnish on-site on our pilot-scale disc refiner that is connected to our stock system.
Several major chemical suppliers and paper producers also tested their product on our pilot paper machine. The desired outcomes were clearly defined: increase the filler content while maintaining the key paper properties desired by the mill.
The trials were successful both from the point of view of the supplier and that of the mill people because they helped to evaluate the potential savings in fibre supply for the mill while maintaining its product quality.
PPC: Can you give a specific example of a new technology that was tested on the pilot machine?
Gauthier: AstenJohnson tested a new fabric on the pilot paper machine.
Paprican’s pilot paper machine is a valuable tool to evaluate the drainage characteristics of different forming fabrics. It is relatively inexpensive compared to other available options, and allows our clients to operate in a low-risk environment.
Our pilot paper machine forming section is equipped with various whitewater collecting pans mounted with flow meters that are connected to our PI data acquisition system; this enables us to characterize the drainage profile while the paper machine is running.
Our pulp and paper-testing laboratory can also evaluate the physical properties of the paper produced on the pilot machine, including formation, fines distribution in the z-direction, and curl.
PPC: Your machine has a twin-wire former while several mills in Canada have Fourdrinier. Is there any technology installed on this machine that can be applied to older machines to increase their operating speed?
Gauthier: We have learned the details for paper formation mechanism by running trials on the pilot paper machine. These concepts could be applied to Fourdrinier machines as well. We know enough about paper formation to address questions related to formation on older machines. Our pilot machine has no open draw, since the sheet is fully supported from the forming section to the dryer section. In commercial machines, sheet breaks occur most frequently in the first open draw of the wet end. Depending on the age of the machine at the mill, the first open draw might be located after the first, second or third press. The transfer of an unsupported wet web through an open draw is undesirable, especially at higher machine speeds.
Paprican has developed a simple and inexpensive method for closing open draws between the presses, or between the last press and the dryer section of a paper machine. This technology is installed on our pilot paper machine.
The system consists of an air doctor that separates the sheet from the press roll, and a suction transfer roll that retains the sheet on the surface of the drying fabric.
The pilot paper machine can be used to investigate how this technology could be applied to a client’s mill to improve machine efficiency or to allow the use of a weaker furnish.
PPC: What are the benefits of testing a new concept at the pilot scale? Isn’t it more representative to rather implement the technology or optimize the process directly on the commercial machine?
Gauthier: Testing new concepts on Paprican’s pilot paper machine offers many advantages. Our pilot paper machine is highly flexible and reaches steady-state conditions much faster than commercial paper machines. In addition, we can better control the process than in a mill environment and it is easier to vary one condition at a time.
We have developed protocols for a two-day trial that can identify the best operating conditions in order to achieve the best paper formation possible. In those two days, we can evaluate more than 30 different operating conditions involving changes in jet impingement velocity, headbox consistency, vacuum levels, retention aid dosage, and other parameters.
The benefits for a mill are enormous as such a trial on a commercial paper machine would be quite expensive, very difficult to monitor effectively, and even almost impossible to perform.
PPC: What makes Paprican’s pilot paper machine unique?
Pikulik: Paprican’s pilot paper machine is the only high speed twin-wire machine in North America. The machine was designed as a slice of a commercial machine but as a tool for papermakers. With its advanced chemical addition system, fines recovery and on-line charge and retention measurement it is particularly suitable for wet end chemistry trials.
Gauthier: For paper machines, most of the issues are tied to reducing water usage through closing up the white water system. Paprican’s pilot paper machine was des
igned to address challenging questions for paper machine operation related to progressive system closure. This gives a significant research capability as we can operate for our clients anywhere in the range of 100% open (no system closure) to 100% closed.
Trials require team work and our team has several years of experience working together, running the pilot paper machine, and is supported by experts in all fields. Our team supports the client running the trial in designing an experimental plan to ensure that the work performed met the clients’ objectives and desired outcomes. Team meetings with the clients evaluate the results after each run day and ensure the customers get the most out of the next trial day.
PPC: Can you describe the pilot paper machine?
Gauthier: One unique feature of Paprican’s pilot paper machine is its forming section. The forming section can rotate, enabling us to simulate any former configuration from 100% roll forming to 100% gap forming or any combination of the two.
The press section consists of a three-nip press followed by a fourth press (shoe press). Only the second nip is mandatory to transfer the sheet from the forming section to the dryer section. The web can be pressed one, two, three or four times so that our press section can simulate any press configuration.
The machine has no open-draw which allows us to run any type of grade. It is fully equipped with a chemical addition system permitting to simultaneously add up to eight different chemicals on the machine. Our PI data acquisition system acquires all relevant operating conditions including vacuum levels, headbox and white water consistency, ashes, cationic demand, and conductivity.
Our dryer section comprises two Papridry(TM) units, allowing the achievement of drying rates one order of magnitude higher than a conventional dryer while improving paper surface properties.
PPC: I noticed the dryer section is somehow different from conventional dryer sections. Can you tell more about it?
Gauthier: Papridry(TM) is a new drying concept developed at Paprican and scaled up from the laboratory to the pilot machine. In this method, the wet sheet arriving from the press section is pressed onto the surface of a large-diameter, steam-heated cylinder.
The drying rate is further increased by impingement of a hot combustion gas in the hood surrounding the cylinder. With the installation on our pilot machine, we routinely obtain drying rates ten times greater than those found on a commercial cylinder dryer.
Furthermore, the sheet dried in this way is denser, smoother, and has better print quality than a conventionally-dried sheet.
The concept is now ready for the first commercial application. It offers excellent opportunities for retrofitting existing machines, to improve their drying capacity or the surface properties, or to upgrade the machine by installing a soft calender or a size press within the existing dryer section without changing the position of the reel.
Pikulik: While major innovations were introduced in papermaking operations such as forming pressing and calendering, drying remained essentially unchanged throughout 200 years of paper machine development. Papridry can revolutionize drying of paper and board by providing an order of magnitude higher drying rate and improved product quality.
We currently have a three-way contract between Paprican, GL&V who has the license to supply the machine part for this technology, and ABB Drying (today Andritz), licensed to supply the hoods and air system. If a company were interested, we would add their mill to this group to look at their potential opportunities. Paprican has already carried out simulations a potential installation. Replacing five drying cylinders with one three-metre diameter unit would increase the machine capacity by 20%.
PPC: Now a lot of interest in Canada has been in the calendering. Have there been any developments in that section?
Gauthier: We do have a laboratory calender and we have done a lot of development on that machine but it is not on-line yet.
We know pretty well the effects of the nip in a soft calendar versus that in a hard calender and how to optimize the operation to get the same finish but limit the strength losses of the paper. It is important to achieve the same surface finish but the higher strength means that you can reduce your refining (and reduce the energy cost) or reduce the amount of raw fibre in your furnish.
PPC: Because energy is such a huge question these days, could you tell me if the improvements that companies have asked for lead to a higher usage of energy or not?
Gauthier: On the pilot paper machine projects, we are looking at progressive system closure because there is a lot of warm water that is lost in the mills. We are able to close the system by taking this warm water and using it to preheat other streams of water. So this is one thing that we can evaluate on the machine and it also has benefits for the environment.
PPC: You say that there are about 240 people working here. Are they working only in response to requests or is there ongoing research into improving the product for pulp and paper companies?
Gauthier: The Paprican Research Program Committee, made up of people from both mills and from Paprican, decide where we should go for the next four years or eight years with research projects. This core research program covers different areas, from tree genetics to final products. The research projects do not answer specific questions that the mills ask, but are designed to answer strategic questions concerning future technologies or future products.
Work done on specific issues and specific questions asked by member mills are done on a contract basis and the results are confidential to whomever is asking for our services.
PPC: Let’s say if the supplier tests something and it works here, can they can continue to develop and market it?
Gauthier: Yes, I think that’s why they actually come here. Some of the suppliers are really convinced of what they are doing and have tried their product in mills before coming here. But there are a lot of variabilities in the mill that can affect the benefits analysis of a new product or equipment.
They like to come here because we have good control of our pilot machine. What we are doing is not only focussing on the production of the paper; we are really trying to understand the process and focus on the trial objective. I know that some of those suppliers have used the results obtained on the pilot machine as a marketing tool.
PPC: Thank you for your time.P&PC