Bayer upgrades control and safety system at Norwich site
Norwich, UK – Bayer CropScience AG has competed a major system modernisation project at its UK site in Norwich manufactures intermediate bulk chemicals for use in herbicides.
The project centred on the to modernise the process control and safety system at a plant manufacturing p-cyanophenylacetate (CPA) – an intermediate material in herbicide production. The CPA plant is one section of a four-part production chain and runs a single stream, single product batch process with up to six different batches present in the plant at any one time.
The existing control and safety systems used on the CPA plant were proving increasingly expensive to maintain, and the outdated technology made it difficult and costly to keep site engineers trained to a level where they were confident to make process improvements.
Impending obsolescence in terms of components and parts also threatened Bayer’s ability to effectively support the existing systems into the future. In addition, in light of legislative changes, the site had also embarked on a programme to revisit legacy safety systems to ensure its previous excellent safety record would be maintained by continued strict adherence to best practice.
Any proposed control and safety system had to underpin Bayer’s strategy of continually improving its process technology, whilst maintaining high performance and ongoing environmental protection and safety.
To this end, the vendor evaluation sought an integrated control and safety system solution. As part of the evaluation of the safety instrumented system, an exercise was set in which all vendors were required to demonstrate how their system might meet the typical safety requirements for the project.
Siemens demonstrated how the application would be handled within a Simatic PCS 7 DCS solution and proposed the use of the Safety Matrix cause & effect tool to simplify the engineering of the Safety Instrumented System (SIS) aspect.
PCS 7 also won points in the evaluation process for its approach to licensing, ease of expansion, simple engineering and higher performance. Bayer appreciated Siemens’ flexible approach to working with other integrators and willingness to supply DCS hardware and software directly. Ultimately, a decision was made in favour of PCS 7 with integrated failsafe functions in combination with the Simatic BATCH management system.
The system solution comprises approximately 1200 I/O points and uses Simatic PCS 7 with integrated safety and Simatic Batch. Simatic Batch is S88 compliant with part of the project required to pass batch data through to the corporate manufacturing execution system.
The safety system is engineered using the Safety Matrix tool and is designed to support many aspects of the typical IEC61511 safety lifecycle. A client server architecture was used, with full redundancy of operator station (OS) servers.
A strong feature of PCS 7 with safety integrated that appealed to Bayer is the flexible modular redundancy (FMR) concept. Depending on the requirements of automation or safety, it is possible to define individual redundancy levels for the various layers in the automation hierarchy. This gives total flexibility at the controller, fieldbus and IO levels.
The benefit of this approach is that it delivers high plant availability – a fundamental consideration for this project. Also when considering the safety aspects of the overall system, the FMR concept means that all the differing voting requirements for Safety Instrumented Functions (1oo2, 2oo3 etc) have been easily accommodated, whilst downtime from spurious trips is minimised.
The new Bayer control system has an integrated approach to safety so that various safety applications can be implemented within the same overall system. This delivers a number of benefits for Bayer, such as cost savings resulting from the use of common engineering tools, reduced requirements for training and spares, as well as simplified maintenance procedures.
In addition, the cost of engineering is cut because data can be more readily passed between the control and Safety Instrumented System without additional hardware or configuration of communications gateways. Time synchronisation and Sequence of Events reporting (SOE) also become easier. All this has helped to achieve the overall objective of an integrated, single system giving a single window approach with complete process visibility for Bayer’s operators.
Integrated diagnostics and system-wide asset management tools give increased scope for improved asset optimisation of SIS assets. In addition to cost savings, integration offers Bayer the potential for use of more integrated tools, which in turn help reduce the possibility of systematic errors within systems.
By removing the need to interface disparate systems, data mapping is reduced and further risk of errors eliminated during the design and commissioning phase.
Bayer’s site safety engineers have found the Safety Matrix cause and effect configuration tool extremely useful. Since the tool generates the safety system logic directly from a cause and effect format, it significantly reduces engineering and testing time, and minimises the risk of errors.
Crucially, from Bayer’s point of view, it also makes subsequent change management straightforward. The cause and effect documentation produced within the engineering system becomes the master document for SIS logic, and also forms the basis for the operator displays.
One benefits achieved from the modernisation of the Bayer system has been improved visibility for the plant operators. The use of Sequential Flow Charts has simplified the engineering of sequences, and the built-in SFC visualisation makes it easy for operators to determine the exact status of the sequence and quickly troubleshoot any problems during normal batch operation.
Safety critical trips and interlocks are shown in a cause and effect format in the Safety Matrix Viewer which gives an intuitive way of assessing the status of the safety system, and the ability to integrate the information from the safety controllers has also been a significant benefit.
Finally, the use of a block structured, object-oriented approach enables the use of standard libraries for this plant and, subsequently, for other plants on the same site.
Simatic PCS 7 is used at Bayer CropScience plants in other countries, and these are often implemented and supported by a central engineering team working for Bayer Technical Services. The library approach will help deliver economies in engineering and make the various systems all the more supportable.
The major system project instigated between Bayer and Siemens has achieved its goal of developing a purpose-built, integrated control and safety system that is maintained by the Bayer manufacturing site personnel.
According to Siemens, the consistent use of library blocks ensures standard CFC and Faceplates across all plants. Batch control and data logging are communicated up to the site plant management systems, and the system is meeting exacting high availability targets.
The previously expensive plant maintenance costs and obsolescence issues have been removed and robust safety systems further enhanced, the vendor said. Most importantly, it added, it has given Bayer the flexibility ‘by design’ to operations resulting in real operational efficiencies aptly demonstrated through the significant production gains now being seen at the Norwich site.