A few years ago, Arkhangelsk Pulp and Paper Mill in Russia set out to modernize the washing plant in their bleached pulp production line. The reasons behind the decision were increased environmental requirements and the old drum filter battery becoming obsolete.
The installation of the new equipment started in summer 2014. All the work for the final assembly, connection and testing of the new system were performed during a two-week shutdown of the plant in October, which also saw the commissioning work completed.
Decision to go ahead without delay
“We’d had plans for the washing system for a long time, but somehow we had always put it off for future projects. Finally, in 2012 we decided that the project simply had to be implemented without any more delays. The existing washing plant was in poor condition and was deteriorating month by month,” says Pavel Smirnov, Director of Production Development.
“We selected two suppliers: Valmet and GL&V. After visiting a number of reference plants, reading feedback, and analyzing potential problems, we chose a Valmet TwinRoll press, which had a number of advantages that you can’t get from other suppliers.”
“We wanted to replace equipment, but we also wanted to optimize the consumption of water, steam, and bleaching chemicals. Therefore, we decided to install three TwinRoll presses, which could easily be fitted with oxygen delignification in future. This project was connected to the shutdown of the main production line; this meant that the project had to be completed within a strict period of time, because the line had to be restarted on time.”
Targets achieved
The new line has been working for more than eight months already. Pavel describes the results achieved in comparison with the previous washing plant:
“First of all, water consumption has been significantly reduced, and consequently, the amount of liquor sent to the evaporation station has also decreased. For this reason, one evaporation station can now be used to extend the capacity of other facilities. At the same time, we now have more precise control over the process, and we can easily change the process conditions depending on the prevailing situation. For example, if we want to adjust the amount of washing water (the dilution factor) and the amount of liquor for evaporation, we can easily do this now.
After several months of operation, the plant has already reached almost all the guaranteed values. The test period was completed in May, and all the process guarantees have been successfully fulfilled.
“We have been cooperating with Valmet for a long time, and so far, the experience has been extremely good. They have responded to all our requests. For example, during the commissioning works they worked 24 hours a day with many people involved. They always met our needs”.
“Long-standing plans come true”
Vadim Moseev, Line Manager of the bleached pulp production department, is also satisfied with the results of the modernization.
“This project brought our long-standing plans to fruition: the concentration of black liquor for evaporation increased significantly, and now it is never lower than 17.5%. This helps to reduce steam consumption for evaporation, and the washing results have improved as well. After excluding molecular chlorine some years ago, we had first-stage, low-consistency bleaching before the project. Now we’ve significantly increased the consistency of bleaching, which has given us the opportunity to decrease our overall water consumption as well,” Vadim Moseev points out.
“I’d particularly like to highlight the competence of Valmet’s specialists and give credit to their skills and knowledge of the process. Of course, there were problems as well. However, despite the language barrier, we always reached a common understanding. It was essential that the project was
implemented in a 14-day period from shutdown to the start-up of the digester. It was also important that we managed to arrange 24-hour work on the site. All the new equipment was successfully started by pushing the button – the result of excellent cooperation during the preparation and implementation of the project.”
Valmet’s TwinRoll presses are quite popular in Russia. There are more than twenty-five presses operating in large pulp mills around the country in a number of washing and bleaching, high consisteny refining and dewatering plants. Now they are also operating at Arkhangelsk Pulp and Paper Mill.
(First published in March 2015 issue of Forward, Valmet’smonthly customer magazine).
