This article was printed in CONTROL's October 2009 edition.
By Juan Jorge Caceres, Alejandro Erazo, Marco Vidal Cruz, Mauricio Quintana M, Gunars Luks Guzman
To compete in the global pulping industry, pulp manufacturers need world class mills producing high-quality pulp efficiently and reliably. Profitability is challenging as material, energy and transportation costs rise. The environment must be protected, leading to ever stricter environmental and other regulations.
Celulosa Arauco met these challenges head-on by turning to digital automation when it built the world's largest smart mill in Nueva Aldea, Chile, capable of producing 856,000 air-dried tons of kraft cellulose per year. The digitally integrated mill achieved 93.6% of targeted production in its first six months of operation, on a monthly basis, and haswe since ramped up to full production according to plan.
A key factor in the mill's success is the use of the latest digital architecture and bus technology, which contributed to the fast start-up and continues to provide predictive diagnostics. "The plant automation technology used on this project has enabled us to improve safety and reduce emissions," said Gunars Luks Guzman, Mill Manager at Nueva Aldea. "We've also managed to maintain production at the targeted levels."
Celulosa Arauco is one of the world's largest forestry companies measured by plantation area and production of kraft wood pulp and sawn timber and wood panels. The company has combined annual capacity of approximately 3.1 million metric tons of bleached and unbleached kraft pulp. Its 610,000 hectares constitute the largest holding of forest plantations in Chile.
The pulp mill is actually phase two of the Nueva Aldea project. Phase one, consisting of a wood processing plant that includes a sawmill and plywood manufacturing plant, was put into operation at the end of 2004. Of the total project cost of $1.4 billion, $150 million was spent on phase one, $850 million was invested in the pulp mill, and $400 million on forestry and other indirect items. The mill includes two fiber lines, one for radiata pine and the other for eucalyptus.
The mill has brought many jobs to the region. An average of 3,300 people were working on site during construction, and the entire project will provide permanent employment for 1,200 people including 200 at the pulp mill.
Environment, Safety and Quality Are Top Goals
"The three most important goals of this plant are the protection of the environment, safety of our employees, and production quality," Luks said. Arauco chose equipment that complies with the Best Available Technologies (BAT) Directive of the European Union, which is required for pulp mills operating in Europe as of September 2007. Safety and environmental concerns have also led the plant to obtain 1SO/IEC 14000 and 18000 auditing and certification. Underscoring its environmental commitment, the plant pioneered in performing tertiary treatment of its effluent stream, which is carried out by only five other pulp mills in the world.
The Nueva Aldea mill also includes a biomass power plant which generates 30,000 kilowatts of electricity and supplies power to the local electrical grid as well as the mill. The biomass power plant is expected to reduce greenhouse gas emissions by a approximately 2.2 million tons of carbon dioxide through 2025. The United Nation's CDM Executive Board has issued approximately 240,000 tons of certified emissions reduction (CER) credits for the project, representing the CO2 equivalent saved each year.
Automation strategy is critical to the Nueva Aldea plant. The plant's management selected Emerson Process Management's (www.emersonprocess.com) PlantWeb digital plant architecture and DeltaV digital automation system. Training, simulation, start-up and commissioning were managed through Emerson and Arauco teamwork.
"The whole plant from beginning to end was automated from the moment we feed the logs into the chipper until a bale of pulp emerges at the end," said Alejandro Erazo, distributed control systems project engineer for Arauco. "Our objective was to use the most modern technology in the market and use it in the best way possible, to make each part of the project easier, from engineering to configuration to startup up the plant."
Mauricio Quintana, systems supervisor, added, "The fact that the automation system is built for digital bus technology allowed us to interconnect several types of networking protocols. Foundation fieldbus, for instance, was used for all the instrumentation, comprising the world's largest pulp mill installation of this technology. We used DeviceNet for motor control center, motor controls and other devices. Profibus was used for discrete remote I/O points and also to interconnect many PLCs."
Complete Digital Automation Solution
Emerson automation and service experts from Argentina and Chile worked with Celulosa Arauco to provide a completely integrated digital solution. Emerson wrote a functional description specification (FDS) for managing the automation of the project; Arauco delivered the FDS to vendors, who returned their digital configuration data for entry into the systems database. This proved valuable in efficiently integrating the work of a number of suppliers.
Emerson supplied the smart mill infrastructure built around its PlantWeb digital architecture and Foundation fieldbus networking. The solution integrates 3,300 Foundation fieldbus devices including flow, level, pressure and temperature instruments and valves with digital valve controllers. Predictive diagnostics information is collected from intelligent devices throughout the mill by predictive maintenance software that delivers alarms and data to operations and maintenance personnel.
In this completely integrated mill, the architecture and its digital system control more than 2,100 Rockwell Automation (www.rockwellautomation.com) E3 and E3+ motor control centers (MCCs) through DeviceNet, more than 3,500 discrete remote I/O points through Profibus DP, and more than 340 variable-speed drives though Profibus DP. The DeltaV system also interfaces with more than 15 PLCs through Profibus DP and special analyzers through Modbus. Emerson also provided Foundation fieldbus consulting, standard definitions and automatic database generation and other services.
A Microsoft Access application was developed to provide output for configuring the digital automation system directly through an ODBC connection. Information on all system I/O interface cards, Foundation fieldbus cards and devices, Profibus devices, DeviceNet devices and single I/O channels was captured in the application. Indexing and integrity checking was performed to detect possible errors and loss of data.
A simple form provided the ability to assign I/O interface cards according to availability of their respective carrier slots. Once the I/O slots were loaded, the form was used to allocate Foundation fieldbus, Profibus or DeviceNet segments to available interface ports. A subform showed the list of devices attached to any selected segment. With all the buses assigned to corresponding I/O card ports, the final step was to create tables for bulk export to the DeltaV digital automation system.
The application provided the option to select which type of objects to import into each process. Special reports were created for hardware integration and system configuration. Others with more detailed information, such as physical location for each signal in control cabinets, device settings, instrument ranges, etc., were used for software configuration.
This automated approach to the database generation greatly reduced the amount of time required for configuration, resulted in an error-free database population and provided a source of information that was re-used for documentation and training, simulation and test sheets.
Digital Technology Speeds Configuration and Start-Up
"A very good example of the benefits of digital bus technology is provided by the intelligent motor control configuration," Erazo said. "In previous projects where we had no intelligent motor controls (MCC), configuration of a complete MCC for 30 motors could take two weeks to one month. Now it takes just half a day to do the same job.
"Configuring a valve is also much faster than before. On previous projects, we could spend up to half a day trying to get a valve to move to the chosen setpoint as part of the calibration process. Today all we have to do is press a button and it self-calibrates. If a problem ever occurs with the valve, we can get the diagnosis immediately. By using Foundation fieldbus and the diagnostic capabilities of the predictive maintenance software, we can quickly determine whether the problem is with the actuator or the transmitter, or if it's only a calibration problem."
Juan Jorge Cáceres, maintenance manager, adds, "A key advantage of the predictive maintenance software is the amount of information it provides. It tells us the state of calibration and if there is a malfunction, such as an actuator problem in a valve, so that we can fix it before it forces us to shut down parts of the plant. The advanced diagnostics also help us prevent damage to the environment and increase the utilization of the plant."
Erazo added: "Digital bus technology makes it possible to do our diagnostic and often our repair work from the main control areas rather than on the ground. Wireless networks enable our technicians to go all over the plant with their laptops, testing equipment much faster than in the past. We had practically no errors in the digital automation system, and we started up the plant successfully and quickly. The technology made configuration of the plant easier."
To further ensure smooth start-up, Emerson performed off-line testing using high-fidelity simulation to validate operations and configuration and to familiarize operators.
"We checked all the logics programmed in the digital system for the different areas, area by area, together with the vendor of the associated machine," said Erazo. "We did it by simulating the real process in the plant, so that we could be 100% certain that the logic was good, and we wouldn't have any problems during start-up.
In addition to simulator training, operators found consoles easy and intuitive. "I didn't take a training class on how to operate with the system, but it turned out not be necessary," commented Marcos Vidal, superintendent in the mill's liquor area. "That's because the system is very easy to operate. It's very similar to Windows. Built-in diagnostics make it easy to detect and determine the cause of problems."
Project Has Met Its Goals
"Our priorities are the safety of our people, the environment and production," Quintana said. "The system, along with all the associated connectivity tools, diagnostics, smart controls etc., has helped us achieve these goals. The system is open and provides a wide range of connectivity so in the future it will allow us to continue developing and expanding, and taking advantage of the communication standards in the market."
"Start-up at Nueva Aldea went according to plan," Luks said. "From the beginning, we began to plan the installation of the equipment from the point of view of risk matrices. We assessed all the risks that each stages of the operation could face, from receiving and start-up to production at the factory. This created a level of concern and attentiveness that has made it possible to operate not only without major accidents. but practically without any incidents at all.
"We adopted a gradual start-up curve that meant we had control of the processes at all times, maintaining as top priority personal safety and environmental protection, and we were able to achieve our goals," continued Luks. "Our environmental performance is so good that we will soon be able to generate additional revenues by entering the carbon offset market. The equipment and control technology used have helped us achieve prime quality from the first days of plant operation."
Luks concluded, "The plant is designed to turn out 856,000 tons of cellulose a year. By April, we reached 93.8% of that target on a monthly basis. Digital technology has helped us reach this production level while maintaining the safety of our people and of the environment. As with all projects, this one demanded much dedication and energy on the part of all the participants. Despite the huge scope of this project, it was completed on time largely due to the great support we received.
"Following the successful start-up, we have continued to increase our output in a sustainable way allowing Nueva Aldea to become a development pillar for the entire region."
Juan Jorge Caceres, Alejandro Erazo, Marco Vidal Cruz, Mauricio Quintana M, and Gunars Luks Guzman are all employees of Celulosa Arauco Nueva Aldea.