Justifying a system upgrade

27 February 2023

Roel Mulder explains some of the process problems that might indicate the need for a process control system upgrade and talks about the benefits that modern systems can offer.

Modernisation of process control and safety systems is frequently required when production capacity is expanding, or when the exchange of production data is needed for cloud-based analytical programs. Most distributed control systems (DCS) and safety instrumented systems (SIS) are expected to operate for many years and so strategical investment will be required, with the implementation of open technologies that can be supported for several decades. Extensions to existing control systems may also initiate an upgrade to the latest supported architecture. 

Making the transition to a modern distributed control system can be extremely challenging, requiring justification of capital expenditure, selecting the right supplier, implementing the solution and creating a roadmap for the future. Experienced support is needed to ensure success, especially if migrating to a control system from a different vendor to the one already installed or projects requiring hot cross overs.

Most control system modernisation projects are initiated when ageing hardware starts to become unreliable, affecting production availability, quality, throughput and profitability. However, other signs of an outdated control system could be that production costs keep rising, production is inflexible, business systems lack meaningful plant floor production data, and obsolete system support costs continue to increase. All of these issues will drive the need for system modernisation. Plant operators are generally tasked to do more with the assets they have. However, when systems become obsolete, hardware is difficult to source and costly to support, making a system migration necessary. 

Justification for modernisation will depend on the existing situation in terms of condition and performance and functionality provided by the current DCS. Operators within the chemical industry, for example, will be keen to increase productivity and throughput. That is often hampered by an aging control system – with unreliable hardware and software often causing periods of downtime and frequent maintenance. Modernisation helps eliminate those issues, while providing a range of benefits, such as high-performance interfaces that incorporate human centred design and alarm rationalisation. This helps operators to control the plant more efficiently, identify issues more quickly, make improved decisions, reduce errors and increase overall productivity. 

Modern functionality such as remote access to critical control system data, enhances operator efficiency further, allowing issues to be addressed immediately and contributing to improvements in plant safety and throughput.

Modern DCS can provide state-based control that helps to increase production efficiency by transitioning from a reliance on operators to fully automated control sequences that ensure consistency and process optimisation. Advanced process control, process learning and adaptive control functionality enable optimisation of interactive processes and reduced variability under changing process conditions. This helps to reduce operator requirements, increase throughput and lower energy consumption.

For companies in the life sciences industry, ageing control technology can prevent consistent, fully documented and optimised production. By modernising the control system and manufacturing software they can eliminate operator interventions that introduce variability and extensive documentation; enable efficient and compliant, fully automated electronic record keeping; and simplify system maintenance and standardisation across their facilities.

The starting point for most projects is establishing how much configuration will be required to modernise the existing system. Emerson can offer a software tool that analyses the controller configurations of legacy process control systems, safety instrumented systems and PLCs. A detailed configuration report then helps support the decision on moving forward with a DCS modernisation. 

Although control system modernisation processes and procedures are clearly defined, project options range from ‘rip and replace’ of the existing DCS, to a connect solution which keeps some of the existing controller and I/O in place and provides new operator workstations and the ability to expand new areas with hardware. This connect method also provides a way to switch over control to the new system in small increments.

Roel Mulder is Director System Migration & Modernisation Europe at Emerson.

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