Developing a Justification for a DCS Migration

Rockwell

THERE are many trends emerging in the process automation space and the chemical processing industry. However, most of the industry thought leadership around plant modernisations is focussed on a few significant developments. First is the demand for smarter assets and the ability to utilise data to drive real-time decision making is accelerating. It is no longer something nice to have but is becoming a necessity. Second, the cost of collecting and aggregating data is at all-time lows. Third, we are seeing a huge challenge in maintaining the human capital to operate and maintain operations.

The engineering skills gap in the UK has been well documented, with many consultants such as Deloitte and PwC pointing to this issue. Deloitte reports the skills gap may leave an estimated 2.4m positions unfilled between 2018 and 2028, resulting in more workers leaving the industry versus coming in. Often that tribal knowledge that is leaving the gates is not easy to replace.

One solution to this dilemma is to improve asset utilisation by modernisation of control systems. Often the success of moving to a modern distributed control system (DCS) is much more than simple technology or a platform play. To get the project started, good planning justification, scope management and industry knowledge are all critical to success.

Navigating the role as an automation professional is difficult, and it gets more difficult every day. It is especially difficult when dealing with legacy systems. According to ARC advisory group, US$65bn worth of automation is reaching end of life. Of that, US$12bn is 25 years old. The Plant Engineering Maintenance survey found that 40% of the respondents said that the leading cause of downtime for them was ageing equipment.

Beyond downtime, legacy equipment is not the only thing impacting performance. One of the biggest challenges is the retirement of the Baby Boomers generation which is predicted to give up work in the coming years. Moreover, we are having trouble with Millennial retention. According to the Deloitte Global Millennial Survey 2019 only 28% of the 13,516 respondents questioned expect to stay with their employers for the next five years.

It is not only migration from old legacy DCS systems that will benefit from a migration to a modern DCS, but also those who operate on traditional PLC and SCADA systems. Those disconnected systems are not designed and ready made for digital platforms like PlantPAx DCS does. This system helps producers make more informed decisions based on the mapping of data structures and pre-generated reports in real-time to transform to a connected enterprise. Another advantage is that a modern DCS follows bespoke standards to comply to security regulations with testing and documentation, full versioning of control blocks and build in security requirements for least privileged user access.

The need for migration

There are external factors at play as well. Kaspersky has indicated that in 2017, 54% of companies experienced an industrial control system security incident. Alongside these facts and figures, daily life is a series of questions about asset utilisation, data visualisation, new standards, new regulations, and IT/OT convergence. Many of those conversations can lead to requests that the legacy system may not be able to even accommodate. It is forcing operators to consider migration. But migration is daunting because it often represents a once-in-a-generation level of change.

As automation professionals, we all have issues to solve that are often legacy system related, and they become the drivers that push us to pursue migration. Obviously, the priorities will vary but there are common issues such as poor documentation, cybersecurity, resource losses, system failures, system limitations, and new standards and technology.

DCS is for process systems and these can be continuous or batch systems. The focus is on controlling process loops such as temperatures, levels, pressures, conductivity to a certain setpoint in narrow bands. In other words, if the process is facing a problem, the system must react in a quick and fast way to control this and take subsequent emergency actions to correct it. The reliability of the process control system is paramount that will warrant the safety and influence the risk of a plant.

Discrete control systems, like packaging lines or assembly lines are sequence driven, but have mostly only digital inputs and outputs to give feedback if the clamp is completely open or closed or to start the conveyor. In these processes we see high numbers of I/Os and we need to have very fast response times. This is the world of the PLC; a traditional DCS system cannot handle the amount of I/O and its response is too slow.

The DCS migration route is crucial to remain competitive in difficult markets that suffer from low margins or high competition like the chemical industry is. PlantPAx Model Predictive Control (MPC) from Rockwell Automation is designed to drive maximum performance in the face of these challenging control situations. For more than 25 years, MPC has proven its ability to address control problems like these where a proportional-integral-derivate controller simply does not maximise controller performance. By utilising more robust process models that account for significant process interactions, PlantPAx MPC stabilises process variability and enables the control loops to be pushed closer to process constraints while maintaining an acceptable margin of safety. Even though it is hardware-based, PlantPAx MPC is a full-featured solution capable of handling the most challenging and advanced process control problems. It can manage multiple objectives and process loops while assuring that plant constraints are monitored and enforced.

Other sectors such as such as food and beverage, and consumer packaged goods, cement, metals or oil and gas will also reap benefits of this.

Meeting business needs

The first thing we must do is stop thinking of migration as a goal. Migration is the path to the goals our companies are going to need to release funding to meet. Companies do not release money for better or new equipment, that is not what drives them. They will release money for investments that are aligned with company strategies or business needs that they have. What you need to do is look at presenting your migration as a path to business outcomes that your company wants. If you do that then the chance of you getting funding is going to go up dramatically. One of the first steps should be to identify desirable outcomes that result from your migration.

To justify a migration programme, we must draw a correlation between the migration drivers and the business outcomes that the company desires and cares about. Moreover, we must use those business drivers to show that the cost required for migration will achieve a reasonable return on investment (ROI). This is calculated by taking how much you will gain from the investment and subtracting the amount that you are investing, and then dividing by that same amount. It will return a percentage figure and most companies are looking for ROI in the 25–40% range.

One of the key elements of ROI is the cost of investment. So how do we measure that? When we talk about migration we are usually talking about total installed cost (TIC) and that represents all the project-related costs such as project management, planning and budgeting, engineering and design, testing, training, installation, commissioning and startup, and purchased labour and materials. However, when you talk about ROI, or justification, or costing it is not just TIC that you should be looking at. When we take the TIC and we add in the lifecycle costs associated with maintaining that system and operating it over a period, we call that total cost of ownership (TCO). Lifecycle costs are repeating costs and that means that we must look at TIC over a finite period, 10, 15 or 20 years.

TCO is important as it allows you to compare solutions and options on more than just the basis of what it will cost you to put it in the field. If you are only looking at TIC, then you are going to miss the potential that one of your solutions that you are evaluating is going to cost you a lot more in the long run through maintenance higher costs or training, more expensive spares. When you are looking at justifying a system and comparing options you need to look at both TIC and TCO.