Yinzhou Paper's rebuild for better quality test liner

Yinzhou Paper was established in 1988, and previously had 24 sets of small machines. They have experienced more intense competition as larger Chinese players have entered the market. “Because of our continued rebuilds and upgrades in these years, Yinzhou has became the current competitive company it is", says Li Weier, Chairman of Yinzhou Paper, who is satisfied with the good results. 

“As our partner, Valmet provided advanced equipment to make us more competitive.” Li Weier, Chairman of Yinzhou Paper

Having a mindset for continuous improvement, the management team decided that the linerboard quality of Dongguan’s PM 1 and PM 2 needed a boost. “We had frequent customer complaints regarding the evenness and CD profiles of our test liner, so we decided to replace the headboxes,” says Wang Zhentao, GM of Yinzhou Paper. The existing headboxes were made locally with a design speed of 500 m/min. The mill increased the machine speed to 750 m/min through day-to-day optimization, but the headboxes couldn’t keep up with the higher speed, leading to quality problems.

Better quality test liner

The solution for improved end product quality was two OptiFlo dilution headboxes and two sets of advanced QCS control system. They were installed for the bottom ply of the three-ply linerboard machines in February 2016. “Before the rebuild, the CD profiles on both machines were very poor. Our target for the CD profile variation was about 6 g/m², which we have basically achieved now,” says Production Manager Peng Guojun about the results of the rebuild.

“The two-sigma value of CD profiles was about 2.5 before. Now it is between 0.5 and 0.8, which has achieved the goals of the rebuild,” explains GM Assistant Xiong Pengju.

“Our customers are now satisfied with the end product quality. We see that investing in technological upgrades is necessary, and it benefits us through improved product quality and production cost savings,” Li concludes happily.

Unexpected savings

“We also got unexpected results that are very satisfying,” says Wang Zhentao excitedly. “After installing the new headboxes, we’ve had fewer paper breaks. Last month, we had only eight breaks, whereas we used to have around 50. We also consume less steam, monthly values have gone down from 1.65 tonnes per tonne paper to 1.55 tonnes. Our raw material costs have also fallen, as the new headboxes can produce the same quality from lower-quality fibers, but with a much higher yield.”

“Another obvious difference was that the rebuild enabled us to convert PM 2 to produce paper with a lighter basis weight of 110–130 g/m², and the running speed increased by 30 m/min,” Xiong adds.

“After installing the new headboxes, we’ve had fewer paper breaks. We also consume 7% less steam. Our raw material costs have also fallen, as the new headboxes can produce the same quality from lower-quality fibers, but with a much higher yield.” Wang Zhentao, GM of Yinzhou Paper

Short 86-hour shutdown

The shutdown of both machines to install the new headboxes was planned carefully to minimize the needed downtime, it took only four days from shutdown to start-up. “Thanks to our combined efforts, the project started up ten hours ahead of time,” says Peng and acknowledges the good service attitude of Valmet personnel.

“Technical stability was one of the most important things we considered when choosing suppliers. Valmet met our strict requirements”, says Xiong. “The headboxes are good in many aspects, such as low pressure loss, good formation, and they are easy to operate. The profile adjustment control system is cutting-edge as well.”
 

Better runnability, web uniformity and quality with automation

Yinzhou Paper’s PMs were equipped with Valmet DCS and QCS control, which helped a lot in getting the results they wanted. They also selected Valmet IQ scanners and profilers to replace their old installations, and performance has improved, with better runnability, web uniformity and quality.

“Personally, I think Valmet IQ Scanner is perfect,” says Chen Yongfa, Automation Manager. ”First of all, it has stable runnability, the system interface is easy for the operator. Secondly, its design is very good. The special floating bridge bearing design allows thermal expansion without beam distortion. The filtered air purge system also ensures temperature stability and maintains internal cleanliness. Thirdly, it can provide high precision and fast response. Fourth, dilution control uses dynamic automation mapping tools and corrects the actuator and web response area mapping quickly and accurately,” he continues.

“By using Valmet IQ scanner and profiler, the basis weight, moisture, and caliper are also better and automatically controlled. It also provides precise CD control, helps in achieving the paper quality requirements. The two-sigma value of BW has improved by 64%,” Chen Yongfa explains.

Expensive or worth it?

Investing in paper production is always a big decision. The dilemma is, whether to choose the solution that has the cheapest price tag or the one with most value and return on investment? Yinzhou Paper has their own philosophy: “Good things are always expensive, but you seldom regret your choice,” Li says.

Wang shares Li’s opinion, adding, “Great equipment produces good products, but it is meaningless if we seek only the lowest investment price. If the headbox runs with bad formation, it might cause paper breaks, or bad paper quality, which leads to energy and wasted work and so on, we’re all good at that math,” Wang smiles. “So if all the core components are as good as possible, then energy consumption and all other costs savings are totally different.”

“The results of the project show that our decision to choose Valmet as our partner was very wise. After this rebuild, the quality of our products has improved significantly, which makes it possible to raise our prices. Improving competitiveness is very important to us. As our partner, Valmet provided advanced equipment to make us more competitive,” confirms Li again.

The customers of Yinzhou Paper are now satisfied with the test liner quality. The company sees that investing in technological upgrades is necessary and it benefits them through improved product quality and production cost savings.  

Want to learn more about how to plan a successful rebuild? 

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