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“Our biggest challenge was space. We were replacing two old lines with one modern line with a live mill operating all around us.”
Matti Haukijärvi, UPM Vice President and Project Director.
When UPM Kymi began moving equipment and pouring new foundations for its chemical recovery plant upgrade, it was not entirely clear what they would find underneath the ground. A large portion of the new line was being built around – and over – the two existing lines that were over 30 years old and, by Project Director Matti Haukijärvi’s own admission, were “well worn out.”
Yes, there were a few surprises as old piping runs and electrical cables were uncovered during the demolition. But, each surprise was taken in stride by Haukijärvi and his team. The net result is a massive modernization project that was completed on-time, virtually on-budget, and with a very fine safety and environmental record. Haukijärvi, an understated Finn to be sure, regards the accomplishment as “a very good project.”
The investment of over € 340 million was one of the largest in Finland during the period from 2006-2008, and was designed to secure the long-term efficiency of Kuusankoski’s operations. “We have been producing sulphate pulp in this mill site since 1964,” says Haukijärvi. “This site has a grand history, having been involved in forest products since 1872.”
Focus on recoveryKuusankoski’s fiberlines were modernized when Andritz delivered a new continuous cooking system for the hardwood line in 1999 and retrofitted the old softwood digester with Downflow Lo-Solids® cooking technology in 2001. The upgrades also included Diamondback™ chip bins and a TurboFeed® chip feeding system. With the digesters running well, UPM next looked to eliminate the bottlenecks in the chemical recovery process. “Our equipment was considerably worn, the technology outdated,” says Matti Tikka, Project Manager for the new evaporation plant and the recovery boiler, and now a Production Manager for the new chemical recovery plant. Tikka, an 18-year veteran at Kuusankoski, knows well the mill’s strengths and limitations.
“The efficiency of the two old lines was suffering as maintenance and operating costs were creeping higher,” Tikka says. “Plus, the turbo-generators were undersized so that we could not take advantage of the potential bioenergy we could produce. Also, there were gains in environmental performance that we wanted to make.”
In March 2006, the UPM board approved the investment: two obsolete chemical recovery lines were to be replaced by a single modern one. Scheduled for start-up was the summer of 2008.
The targetsIn addition to updating the technology, there were specific targets for the project (named REC08) according to Haukijärvi. “We wanted to open up critical bottlenecks to improve pulp production, increase the utilization of biofuels, and double our bio-electricity production,” he says. “We also wanted to reduce fossil fuel-based CO2 emissions and improve our energy self-efficiency. We felt we could dramatically reduce NCG discharges and reduce overall air emissions levels by 15-20%.”
The project included a new seven effect evaporation plant from Andritz, an Andritz white liquor plant capable of generating 8500 m3/d of cooking liquor for the mill’s two digesters, and a new Diamondback™ chip bin with pre-steaming and reboiler for the softwood digester. In addition, UPM Kymi installed a new recovery boiler with a 113 MW backpressure extraction turbine-generator, an auxiliary boiler, a NCG-boiler, and new automation equipment.
Some new challengesThe construction of the new chemical recovery island was the biggest ongoing investment project not only for UPM, but also for the Finnish forest industry. As such, it had the full attention of UPM management and the local community. Energy-efficiency was an important aspect.
“Energy-efficiency has become a significant competitive factor for pulp and paper producers,” says UPM´s President and CEO Jussi Pesonen. “UPM has consistently improved its energy efficiency through investments in Finland and other countries.”
The project team challenged itself to improve other efficiencies including project organization, cooperation, safety, and start-up performance. “But the biggest challenge for us was the space limitation,” Haukijärvi says. “Everything was tight, with little or no room for laydown and staging in certain areas. Plus, the new chemical recovery island was being built virtually on top of the existing installations – at a time when the mill was in full production.”
“The Kymi mill continued to run flat out to meet market demands,” Tikka says. “In fact, the pulp mill set a production record during the time we were constructing the new plant.”
“We had six to seven months of pre-work before the machine erection could begin,” Haukijärvi says. “We planned our moves, demolished buildings, moved tanks, and relocated pipelines all while working around a live, operating mill. We were very concerned about safety with all this activity in a concentrated area, but I’m happy to report that there were no major incidents.”
The original thinking was to conduct the project in two phases: with the evaporators, recovery boiler, and turbine-generator coming on-stream in August 2008 and the white liquor plant in February of 2009. However, as work proceeded, it was decided to start all the processes together and do it over the summer of 2008.
JIT constructionOn paper, it looked like a “normal” white liquor plant delivery to Jorma Vento, Andritz’s Project Manager for Chemical Systems. “However, on-site we could see there would be significant chall-enges due to the space limitations.”
Without space inside the mill for material laydown or staging, the coordination with sub-suppliers was extremely critical for large components. “We had Just-In-Time construction where components were transported to the site and lifted directly into final position,” Vento says. “It is amazing that we were able to accomplish this without an accident and to keep the schedule.”
The level of cooperation and coordination during this project was really quite remarkable according to Vento. “All the suppliers had to work around an operating mill,” he says. “The project managers from all the suppliers would come together on a regular basis and try to foresee problems. We would share information with each other about our erection plans to avoid, for example, trying to put two large cranes in the same area.”
Tapio Lintunen, Project Manager for the Andritz evaporators, faced similar challenges. In addition, the weight limitations on local highway bridges precluded Andritz from delivering the evaporator vessels completely assembled. “The largest vessels (9.5 m diameter) weighed too much to be brought in as single units,” Lintunen says. “So, we had to do the final assembly on-site.”
Only two shutdowns were planned for the switchovers from the old systems to the new. A five-day shutdown occurred in August 2007, followed by a three-day shut in May 2008 for the final intecon-nections. The commissioning and start-up occurred exactly on schedule and “perfectly” according to Lintunen. “UPM gave us very high marks for the start-up as our team did a tremendous job.”
Reusing waterAccording to Tikka, there are only proven technologies at Kuusankoski. “We don’t take risks on equipment that we can’t rely on,” he says, “but something new is always welcome.” He cited several Andritz technologies that impressed him with regards to key environmental issues.
One is the condensate segregation and stripping capabilities of the seven-effect evaporator plant from Andritz. According to Sanna Semi, a Sales Engineer with Andritz, most mills normally utilize two or three of the condensate streams from the evaporators. Kuusankoski uses four. “We’re reusing every drop of water that we can,” is how Tikka puts it.
Two of the condensate streams are routed to the fiberline and two to the fiberline and to the recausticizing.
According to Lintunen, “The mill tells us they use 80% of all condensates from our plant as if it was hot washing water in the fiberline and recausticizing. The purity of the condensates is very high.”
Another rather unique aspect of the evaporators is the high dry solids content of the black liquor. “This plant has our liquor heat treatment integrated into the last concentrator in the evaporator train,” Lintunen says. “The concentration of the firing liquor is 85% dry solids, which allows the boiler to generate more energy at lower emissions.”
Another technology cited by Tikka is the chip pre-steaming system with a reboiler that Andritz installed on Kymi’s softwood digester. “With this closed system, not only are we more energy-efficient, but we’ve eliminated any gases escaping to the atmosphere,” Tikka says. “It’s very clean and very efficient.”
A new feature, not involving water consumption, but still environmentally centered, is the new Andritz LimeFire™ burner on the lime kiln. “This is a new design that we originally tested at this mill about four years ago,” says Markku Lankinen, Sales Manager for Andritz. “It reduces NOx emissions by 30% by utilizing an internal turbocharger for flame shaping.”
Best performerHaukijärvi, Tikka, and the rest of the project team managed 50 civil contracts and 100 machine delivery and erection contracts simultaneously to achieve an on-time start-up for the chemical recovery modernization. Not an easy task, but “all part of the job” according to Haukijärvi.
Tikka, too, is very satisfied with the results. “The Andritz systems are producing high dry solids black liquor for the generation of energy from biomass,” he says. “The white liquor quantity and purity to the cooking plant is excellent. And, we’re operating within our environmental limits. “
According to UPM, the investments in the Kymi mill put it in an even better position to become the best performer in the industry.
