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Metris OPP optimizes Suzano Jacareí's digester and generates greater stability in the process

Suzano's Jacareí Mill saw the cooking process being standardized with Metris OPP. Learn how ANDRITZ's advanced controls were able to reduce the standard deviation of the Kappa number and to increase pulp mill productivity.

© Suzano

The Kappa number is one of the most important factors for pulp quality and paper composition. It is like this in all mills in Brazil and it could not be different for Suzano's Jacareí. The mill located in the city of Jacareí (SP) has a capacity of 1,070 kADT/year, has one digester and two bleaching lines. With the optimization carried out by Metris OPP in the mill's digester, it was possible to stabilize the cooking process and reduce the use of chemicals. André Luiz Guimarães, Pulp Production Manager at Suzano Jacareí, considers this project a game changer in the sector. “In fact, when we manage to translate all the variability into a control, which is the main output of a pulp mill, the Kappa number, that's fantastic.”

André Luiz Guimarães

Controlling Kappa is a challenge because it is the main variable in the cooking process and involves controlling temperature, levels, charge, alkali and so on. “Usually, we are very reactive. The operation sees the results and sometimes takes action in terms of temperature or load, it is very much in the hands of the operation”, says André Guimarães.

Prior to Metris OPP, there was bigger process variability, with conventional control loops not operating in an integrated manner and with frequent operator’s actions in order to make adjustments related to the variations. In this sense, an opportunity for operational standardization was identified. Then the long-standing partnership between Suzano Jacareí and ANDRITZ came into action. André Guimarães describes with great satisfaction the results of the challenge accomplished together. “The operator sets the desired output value and the entire digester controls it, which is something extremely complex, since it contains many variables, starting with wood variation. The variability of wood itself brings a variability in control as well. So, the fact that we were able to fit all of this into a model and automate it is amazing.” 

Implementation of Metris OPP in Suzano Jacareí's digester 

The solution implemented by the Metris OPP team in the Suzano Jacareí’s digester began with the formation of the Suzano/ANDRITZ team. Then, logical sequential steps were defined, and the team set the main objective: to stabilize Kappa as a control response variable. “Normally, the controls do not have this range and are restricted to indirectly control the kappa by the stabilization of the residual alkali and by the cooking temperature”, explains Wanderlei Pereira, Executive Manager of Industrial Processes at Suzano Jacareí.

The success of this project, therefore, was to go beyond the conventional and carry out the final Kappa control of the digester pulp discharge.

“When we have this control and reduce variability, all the other control loops that come ahead tend to be more stable as well. This happens because we are talking about the first process, which is the cooking process”, summarizes André Guimarães.

Thinking about the Kappa control for the digester, the group completed other steps until reaching the final objective. The project presented a new proposal to control levels for the impregnation vessel and digester in early November 2019.

Adriano Ramos

"We have already been making parameter adjustments in other control loops that could impact the performance of future Kappa control", says Adriano Ramos, Optimization Specialist at ANDRITZ. In December, the liquor and chip levels were stabilized, and the team moved on to the residual alkali controls and consistency control of the digester discharge.

In December, the liquor and chip levels were stabilized, and the team moved on to the residual alkali controls and consistency control of the digester discharge. 

Integration and persistence to generate new perspectives with Metris OPP 

In just a few months, it was possible to notice the integration and persistence of the team, summing up the knowledge of the ANDRITZ team with the people in charge of operating the plant and the process consultants from Suzano Jacareí.

Carolina

“The teams operated in an extremely collaborative way, with frequent work meetings, technical coherence and an effective implementation strategy.”, recalls Carolina Jardim, Process Consultant at Suzano Jacareí.

Suzano Jacareí focuses on exports. About 90% of the mill's capacity is destined to Europe and Asia, mainly China. In the European scenario, Suzano Jacareí has ​​the exclusive status of being the only producer of TCF pulp in Brazil, which corresponds to around 20% of the allocation of pulp production. Throughout its history, it has been supported by ANDRITZ's analytical maintenance service for about 20 years and since 2010, it has used ANDRITZ digital solutions, with good performance and always achieving its goals. 

Digital solutions in partnership with ANDRITZ have been instrumental in making Suzano a benchmark in the sector. “When we talk about process stability, in the not-too-distant past, the high variability that we had was not a problem, as the customers were not so demanding,” says André Guimarães. Nowadays, the whole world is more connected, an element that brings customers and companies closer. 

A result of this proximity is a greater demand related to the process control. “The better and more stable our controls, the less variability we get in the pulp and the less variability in the machines. It's a win-win chain. Process stability already exists for a long time and all mills are focusing on it. Today, with these new technologies, we have made huge advances and have made Suzano a reference in terms of stability”, summarizes production manager André Guimarães. 

Last adjustments in the optimization process of Suzano Jacareí's digester, H factor control and Kappa control 

The industrial automation process in Suzano Jacareí's digester continued in 2020. The world hardly knew what was to come that year: the Covid-19 pandemic. In Brazil, the biggest in the last 100 years. Overcoming challenges and working safely, the project continued with frequent work meetings, technical coherence, and an effective implementation strategy. 

In April, the team began H factor control. A few months later, in June, Kappa control was finally turned on and digester optimization completed the last stage. Improvements were identified in the pulp production process as well as in the quality of the final product. 

With the optimization implemented, it was possible to achieve results such as an increase in the yield, a reduction in the alkaline load and a reduction in the percentage of rejects in the pulp discharged from the digester. The main goal was also achieved: the reduction of the Kappa standard deviation, which was below the best market references. 

“The stability of the Kappa number in the cooking process is critical for the subsequent step, pre-bleaching and bleaching. Any variation in the Kappa number can directly affect the consumption of bleaching chemicals and/or the physical-mechanical properties of the pulp”, analyzes Carolina Jardim. 

Metris OPP also helped significantly in Suzano Jacareí's operational routine, as the industrial optimization made the operators' work easier. These professionals, who worked on the digester controls manually, were interviewed and participated in training on the proposed new controls. This way, at the end of the project, operators gained time to focus on other parts of the process and development plans.

Wanderlei David Pereira

“We have been in partnership with ANDRITZ for several years, with successful projects to optimize and reduce process variability, in addition to the search for autonomous systems with reduced operator interventions and the operator acting as an analyst”, recalls Wanderlei Pereira.

Of course, all this generates an important financial gain, but the Suzano team was also able to notice the positive aspects of a much better level of control on a daily basis. “When you have the equipment running in a more stable way, it's much better. If not, there are fluctuations all the time, such as a valve in the output control opening more or opening less and the pump or motor load, sometimes higher, sometimes lower. This causes fatigue in the equipment and can result in some type of maintenance problem”, explains André Guimarães.

Metris OPP breaks paradigms and takes another step towards control autonomy at the Suzano Jacareí mill 

The project carried out with the Metris OPP at the Suzano Jacareí mill represented a paradigm shift in terms of process variability and took an important step towards control autonomy. This happens because the variability of the process is related to the main raw material of a pulp mill: wood. 

The cost of wood is one of the most important in the budget for pulp production. The lower the variability, the less fiber degradation and the more cellulose is extracted. “With the same volume of wood entering the system, it is possible to extract more pulp from it, because it degrades less”, explains the Pulp Production Manager André Luiz Guimarães. “Having less variability, hemicellulose chains and even cellulose chains are not degraded. All of this is preserved along the cellulose chain, which prevents it from ending up in the liquor cycle, turning into energy and steam. That is not the focus, the focus is to transform wood into cellulose”, he adds. 

For the Executive Manager of Industrial Processes at Suzano Jacareí, Wanderlei Pereira, the main benefits of Metris technology are the adaptability in using the operator's knowledge through multivariable and integrated controls, and the customization with the equipment's capabilities without suffering significant changes of new investments. 

Adriano Ramos points out that the Metris platform was used in the analysis and monitoring of controls. The Optimization Specialist mention three factors of the ANDRITZ technology that were decisive for the final result of the project. “The differentiators were the advanced control tool that provides control blocks that allow handling of process dead time, Fuzzy logic and MPC controllers.” 

Carolina Jardim confirms the quality of the work carried out and projects the future of Metris OPP technology at Suzano Jacareí: “The Metris technology is spectacular and adds a lot to the entire operational experience. It will be a win-win, no doubt. For sure brought us maturity, broke paradigms. And there is still a long way to go. ” 

From now on, the idea is to keep building BIG APCs for integrated control of complete processes. With the partnership of ANDRITZ, Suzano Jacareí drives the future of mill’s autonomous control and keep moving with open doors for innovation creating new perspectives for development. 

According to André Guimarães the biggest challenge is having an integrated island. “Suzano already has some initiatives in this regard, one of them at Suzano Jacareí. With the integrated islands, as one depends on the other, it is possible to take the digester, washing, delignification areas and integrate these with the evaporation area. With this, it is possible to balance the organic level and inorganic level, all the generated volume of liquor. It is a very cool job that is directly connected to the balance of the plant as a whole”, concludes the Production 

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