To process a greater variety of materials and improve global competitiveness, Mitsubishi Chemical Corporation's Kashima Plant (Tobu Zone) and Mitsubishi Chemical Engineering Corporation contracted with Chiyoda Corporation in May 2004 to construct an additional fractioner for an ethylene plant. Yokogawa's CENTUM CS 3000 R3 was selected as the new control system. After carrying out an extensive study, the customers decided to employ ProSafe-RS as the emergency shutdown system instead of conventional relay-based systems in order to:
- Meet the IEC 61508/JIS C 0508 functional safety standards
- Proactively introduce leading edge technologies
- Accommodate the plant licensors' safety, reliability, and maintainability requirements
- Improve the monitoring and operation functions of the emergency shutdown system
The Challenges and the Solutions
By introducing the ProSafe-RS, the Kashima Plant improved safety, reliability, monitoring, and operation as follows:
- Dramatic improvement in plant safety through compliance with IEC 61508/JIS C 0508 SIL3
ProSafe-RS is certified to comply with the IEC 61508/JIS C 0508 (up to SIL3) international functional safety standards. This affirms that a plant will be securely shut down whenever a critical condition occurs, greatly improving plant safety.
- Achievement of high-level safety while minimizing erroneous trips
ProSafe-RS maintains plant safety at a high level while keeping to a minimum unnecessary trips triggered by a system's own abnormalities. Mitsubishi Chemical's system incorporates redundant CPU and I/O modules that can avoid almost all erroneous trips, contributing to increased reliability and plant availability.
- Improved centralized management of plant information through CENTUM CS 3000 R3 integration
Plant information can be centrally managed thanks to ProSafe-RS's capability to achieve true integration with the CENTUM CS 3000 R3, enabling ProSafe-RS inputs and outputs as well as system operation statuses to be monitored on CENTUM's human interface stations. Emergency operations can also be initiated on the CENTUM stations for better emergency preparedness.
Takayuki Aoyama, Team Leader of the Instrumentation Group at the Maintenance Technology Center, commented:
"Usually introducing a new thing takes time: you must collect various kinds of information about it, then study actual records, reliability, and technological factors. This is even more so when you consider introducing a product that is used to guarantee safety.
This is where ProSafe-RS comes in. Safety instrumented systems can be evaluated according to international standards and certified by a registered certification body. This spares users the trouble of conducting a feasibility study. The safety standards cover a wide range of items and are thorough about maintaining safety during the detailed design phases. As the system design utilized probability theory, engineers are better able to give a logical explanation of it to third parties.
Introduction of the new safety system was a big decision for us as the existing interlock used hardware relays. As we understood the standards as well as the configured actual hardware and software, however, we were convinced that the new system took safety into much greater consideration than conventional systems and that we had made the right decision.
Interlock-related equipment is growing more complex as it is required to ensure safety against all types of failures, and the same was true when panel instruments were replaced by distributed control systems (DCS). For this reason we employed the ProSafe-RS safety instrumented system. We also believe that the time is approaching when all hardware relays will be replaced by CPU-based systems."
Whether you produce petrochemicals, inorganics or intermediates, chemical companies are under cost and margin pressures to deliver products in a timely and efficient manner while maintaining safe and compliant operations. Additionally, chemical companies need to adjust to fluctuating feedstock and energy prices and to provide the most profitable product mix to the market.
Yokogawa has been serving the automation needs of the bulk chemical market globally and is the recognized leader in this market. With products, solutions, and industry expertise, Yokogawa understands your market and production needs and will work with you to provide a reliable, and cost effective solution through the lifecycle of your plant.
Chemical plants rely on continuous and batch production processes, each posing different requirements for a control system. A continuous process calls for a robust and stable control system that will not fail and cause the shutdown of a production line, whereas the emphasis with a batch process is on having a control system that allows great flexibility in making adjustments to formulas, procedures, and the like. Both kinds of systems need to be managed in available quality history of product, and to be able to execute non-routine operations. With its extensive product portfolio, experienced systems engineers, and global sales and service network, Yokogawa has a solution for every plant process.
Petrochemical companies’ needs are extremely diverse. To come out ahead in today’s highly competitive marketplace, producers are striving to improve quality and productivity. Yokogawa provides tailor-made solutions for these needs based on its long and wide-ranging experience in this field.
The ProSafe-RS is a Safety Instrumented System that is certified by the German certification organization (TÜV) to meet Safety Integrity Level (SIL) 3 specified in IEC 61508.
Our distributed control system (DCS) enables automation and control of industrial processes and enhanced business performance. Over 10,000 plants entrust Yokogawa DCS to deliver their production goals.
Contact a Yokogawa Expert to learn how we can help you solve your challenges.