Samsung Petrochemical Co. Ltd. (SPCL), a major Korean petrochemical company, produces 700,000 tons per year of purified terephthalic acid (PTA) at its Daesan plant. PTA, a white powder substance that is produced by oxidizing and refining para-xylene, is a precursor to polyethylene terephthalate (PET), a polyester material that has excellent thermal resistance and wear resistance and is widely used as a substitute for natural cotton fibers and in film packaging, beverage bottles, tire cords, paints, adhesives, and other applications. As of 2010, global annual demand for PTA stood at 39 million tons, and is expected to continue growing by 7% a year until 2016. Growth is especially strong in Asia, particularly China and India. (Source from Petrochemical Industries in ASIA 2013 issue)
SPCL is striving to improve safety at this plant and wants to reduce operator workload and ensure consistent product quality by automating complex operations. To achieve these aims, Yokogawa Korea installed the Exapilot operation efficiency improvement package and integrated it with the plant's existing CENTUM CS 3000 production control system (PCS). With these new systems in place, the SPCL plant is operating flawlessly.
Overview of PTA production process
The Challenges and the Solutions
Up until 2000, SPCL was using the CENTUM CS PCS and an advanced process control (APC) package. Around this time, Exapilot was installed and used on a trial basis, as part of an effort to improve quality control in each department and ensure more efficient production. Within the company's quality control (QC) activity, four different production groups received prizes for their efforts in using this package to automate manual procedures.
When SPCL upgraded from CENTUM CS to CENTUM CS 3000, it extended the use of Exapilot to all other operations throughout the plant, including the startup and shutdown of three oxidation reactors. Prior to the introduction of Exapilot, emergency shutdowns of the reactors were particularly labor intensive, requiring operators to carry out many different manual operations such as ramping down the set points for the reactor temperature controller, opening and shutting valves, transferring intermediate chemicals to temporary storage tanks, and carrying out various other recovery processes. Similarly, many different manual operations were necessary to start up the reactors. Exapilot automated the execution of all these procedures and allowed operators to monitor and confirmed these operations while they were in progress. Safer operation and greater consistency in product quality are available now.
Another very labor intensive operation involved the treatment of the plant's wastewater. The filters used in the separation process need to be cleaned by means of carbon purification. This takes up to eight hours, needs to be done two or three times per day, and requires the manipulation of 15 valves per filter. This process has also been automated using Exapilot, resulting in reducing operator workload.
Assignment of the Internal switches of Exapilot
Jun Ho Hwang of Associate Daesan Maintenance Team, commented, "First of all, our company pays careful attention to quality control, and every department is striving to make improvements in this area. Our group aims to improve efficiency by automating manual procedures as much as possible. This helps to ensure safe operations 24/7, to reduce operator work load, and to ensure the consistent product quality."
He added, "All of our operations are managed by Exapilot. Only the interlocks have been implemented through the CENTUM CS 3000 system. APC software and the Exaplog event analysis package have also been introduced to bring added improvements in efficiency. Maintenance engineers have assigned a total of 160 internal switches for Exapilot configuration, and all the logic is implemented by the skilled operators. So the know-how from the skilled operators is transferred by Exapilot to younger operators. Our central control room is quiet and our production operations have been going smoothly."
Central control room (CENTUM CS 3000 and Exapilot displays)
Chemische fabrieken zijn afhankelijk van continu- en batch-productieprocessen die elk verschillende eisen stellen aan een besturingssysteem. Een continu proces vereist een robuust en stabiel besturingssysteem dat niet faalt en de productielijn doet stilvallen. Bij een batchproces ligt de nadruk ligt op een besturingssysteem dat een grote flexibiliteit biedt bij het aanpassen van o.a. formules en procedures. Beide soorten systemen moeten worden beheerd naar aanleiding van de productiegeschiedenis rond de kwaliteit van het product, en in staat zijn om niet-routinematige werkzaamheden uit te voeren. Met een uitgebreide productportfolio, ervaren systeemingenieurs en wereldwijde verkoop- en servicenetwerk heeft Yokogawa een oplossing voor elk fabrieksproces.
De behoeften van petrochemische bedrijven zijn zeer divers. Om voorop te blijven lopen in de huidige, sterk concurrerende markt, streven producenten naar verbetering van kwaliteit en productiviteit. Yokogawa biedt op maat gemaakte oplossingen voor deze behoeften op basis van haar lange en brede ervaring op dit gebied.
The all inclusive Platform for Advanced Control and Estimation brings multi-variable control, quality estimation, complex custom calculations, and operator user interface design all into one application; in doing so, dramatically reducing deployment time and simplifying maintenance for robust performance.
Procedural Automation (Exapilot) provides a flexible methodology to capture, optimize and retain procedural knowledge in a process plant while meeting requirements in reliability, flexibility, and lifecycle costs.
De DCS maakt automatisering en controle van industriële processen en verbeterde bedrijfsprestaties mogelijk. Meer dan 10.000 fabrieken vertrouwen op Yokogawa DCS om hun productiedoelen te bereiken.