The tail threading system is a very important process during pulp production resumptions. At this stage, stabilizing the dry sheet weight means faster production acceptance on the cutter, reducing process adjustment times for sheet quality parameters. With this challenge in mind, Suzano and ANDRITZ combined their expertise in studies and development of advanced controls with the exclusive technology of Metris UX, leading the Imperatriz Unit mill to improve the production process with greater availability of drying machines.

Metris UX is ANDRITZ's IOT platform that hosts several tools for management and optimization of processes and equipment. The platform is the result of years of knowledge and modern technologies that have been bringing excellent results to customers.

At Suzano, the implementation of advanced controls is related to what the company calls innovability, the union of innovation and sustainability. The projects developed with the ANDRITZ team are part of a routine that aims to facilitate the creation of new solutions and products. “Improvement management is applied in conducting initiatives that will help us achieve our goals. Strategic and priority projects are coordinated and reported within a regular project management routine. Within this routine are the projects developed with the ANDRITZ team”, points out Edson Hélio, Executive Production Manager at Suzano Unit Imperatriz.

Grammage control in tail threading

One of the main challenges facing the pulp industry today is precisely to combine cost with guaranteeing profitability and product quality.

In the case of the Imperatriz Unit, the project in partnership with ANDRITZ started looking at the downtime of the dryer, in which two machines operate. “There was a loss in machine availability due to the time needed to reach the finished product's moisture specification and a low assertiveness in the tail threading due to fluctuations in the sheet grammage”, explains Lucas do Nascimento, Production Consultant at Suzano Imperatriz Unit.

The mass balance control to stabilize the grammage was one of the important points for the project development, as it was previously done manually. "Thus, under the best process conditions, the average time to carry out the tail threading and have the production acceptance was relatively high and depending on the process conditions could be longer", comment Jhonatas Santos and Job Camargo, OPP Analysts of ANDRITZ.

Project development for the control of tail threading

In face of the identified scenario, we began to study the process and created a roadmap of actions and developments in drying, which would support the implementation of an advanced grammage control during the tail threading, which would be able to predict the final sheet grammage at the end of the dryer.

“We concluded that the time for process adjustments and production acceptance on the machines could be reduced with the application of artificial intelligence added to advanced process controls. In this way, the technology would be used to have the fastest production acceptance on the cutter, reducing process adjustment times for sheet quality parameters”, explains Heller Braga, Specialist in Automation and Process Optimization at ANDRITZ.

Suzano approved the idea and then the teamwork continued with the elaboration of a schedule of actions and scheduling of best moments to test the new technology. The first two tests generated adjustments. “The third opportunity came right after a machine shutdown. The Suzano and ANDRITZ teams, after analysis, identified that this would be a good time to test the project again and that's what we did”, says Heller Braga.

After the tests, the team analyzed four downtimes that were used as a reference, registered in November last year. With this, it was observed that the advanced control managed to reduce the passage time by approximately 40%. “At the Imperatriz Unit, the machines in the drying area are not designed to be a bottleneck for production. With the control, we were able to increase the machine's uptime and, consequently, the plant's operational stability”, says Production Consultant Lucas do Nascimento.

After the advanced controls, with the process being resumed more quickly, we reduced the machines' unproductive time. According to Edson Hélio, the results created a new milestone for the Imperatriz Unit. “We increased the availability of the machines, which allowed us to surpass previous monthly production records at the mill”, recalls the Executive Production Manager.

Advanced controls are a key part of the digital transformation process

Advanced process controls are the last instance before formalizing an autonomous industrial mill. They do not replace basic process control, but provide value to what exists. They use information about changing process conditions or constraint influences to make real-time improvements. The objective is to effectively transfer the operators' activities to the automation system.

At Suzano, advanced controls are part of the company's objective of being more and more protagonist and competitive. "Some of our commitments, such as, by 2030, increase exports of renewable energy by 50%, reduce the sending of waste to landfills by 10%, transforming them into by-products, and reduce by 15% the water collected by the industrial operations, have the collaboration of advanced controls that we have developed in our unit in recent years”, explains Edson Hélio.

An important moment to increase machine availability and stabilize grammage deviation in the Imperatriz Unit was the use of virtual sensors. These sensors are created in the Digital Twin application, existing in Metris. Digital Twin uses machine learning to understand the behavior of variables and create models that will be used to predict new soft sensor values. "Previous experiences and the proper use of data science allowed the correct understanding of the opportunities to be worked on, as well as the tools to be used", reports the Executive Production Manager at Suzano Unit Imperatriz.

The realization of this project, therefore, contributed to turning another page in the digital transformation of Suzano Imperatriz. But Edson Hélio reminds us that this movement is not just about embedded technologies. It also involves a new way of thinking. “We believe that digital transformation empowers people to use technology in an uncomplicated, intelligent and agile way”, concludes the Executive Manager.