The importance of industrial automation systems

Yokogawa

The importance of industrial automation systems, and the need for incredibly high quality systems which require little maintenance to improve operational efficiency at refineries.

What is the definition of a “High Quality Automation System”? The answer is subjective depending on your point of view.  As a refinery operator it could be simplified as a system which costs the least to install whilst giving the greatest increase in productivity by optimizing product consistency and volume.  Of course the ownership overheads need to be considered and the intended period for return on investment, however one thing is clear – the refinery will not be efficient without the automation system, even though it is a small percentage of the capital cost of the plant.  Quality comes at a price, but a lifecycle approach to calculating the cost benefits of the plant automation system from beginning to end and top to bottom may change the ownership view to one of “Value” rather than “Cost”.  A subjectively “High Quality” system can therefore be considered to be objectively “High Value”, where the value is a quantifiable measure of improvements in a number of Key Performance Indicators (KPIs) such as operating costs, product quality, product consistency, maintenance costs and process flexibility, plus reliability and timeliness of management information.

The achievement of these Key Performance Indicators is at the core of the latest refinery automation technology using intelligent instrumentation, advanced control, optimization, recipe management and enterprise level integration, yet the technology itself is more and more being considered as a commodity.  So what is it that makes one automation system different to another?

Holistic automation solutions

To answer this question we need to take a helicopters’ eye view of the subject.  The technology is one component of the total solution, which in turn is dependent on the organization surrounding it.  Even within the confines of a project, over the lifecycle of the system, hardware costs will be a minor part.  Extend that view to include product development and the need for the system manufacturer to accommodate legacy and new industry and international standards, maintain integration with other changing management systems whilst investing in innovations to add further value, then it can be seen that the differentiators are now more driven by the vision, commitment, investment and corporate attitude of the system provider.  In other words High Quality Automation Solutions require High Quality Automation Providers, possessing a lifecycle and long term commitment, preferably where this is their core business and focus. This is a Holistic approach to Automation Solution selection encompassing not only the system but its entire lifecycle and environment.

Operational efficiency

For the refinery, operational efficiencies arise from the automation system suppliers’ ability to understand how the process should be optimally operated, then to capture and embed that knowledge such that the process runs at high efficiency in all conditions regardless of human operator variances and changes in raw material quality.

The relationship between Low Maintenance and Operational Efficiencies could be reduced to a simple question of plant availability, however the latest automation technology provides more subtle solutions to provide efficiency improvements over and above this basic KPI.  Considering operational issues first, it is known that in many cases product quality and consistency can change depending on which human operators are on duty, therefore the automation system should provide the means to reduce these variances.  Studies have shown that 40% of incidents in process plants arise from human actions (or inactions), and that in some countries the number of process operators has reduced by over 30% despite production volume being increased over the same period.  To address this cost driven trend, the High Quality system needs to incorporate Advanced Operator Assistance functions to guide the refinery operator through both normal and abnormal operational conditions, thereby reducing commercial risk from product inconsistency, and ensuring corrective actions are actually correct.  This process for improving operational efficiency needs to be a cycle to allow continuous improvement as shown in figure 1, which means the automation system must provide the facilities to measure performance and support easy enhancements.

Figure 1 – Improvement cycle operational efficiency

The effectiveness of operator assistance can be measured in the first instance by on line analysis of tangibles such as the alarm traffic in the system and operator interventions (described later), with the results being used to further fine tune operations and operator training.  For a refining process which may regularly need to change the product attributes, or adapt to quality variances in the raw feed stocks, operational assistance can provide major commercial benefits in terms of the time taken to change the recipe and the amount of off-specification transitional product.  In fact the area of recipe management also provides scope for improved efficiencies and risk reduction if it is well integrated into the automation system.  A high quality system will easily combine regulatory and sequence based applications, and should not be dependent on external recipe management PC’s whilst the application is running as this can compromise production if the external PC fails. 

Advanced process control (APC)

Much has been written on this topic elsewhere, though it is a key factor in refining processes for cost reductions and product consistency.  There has been considerable analysis on the benefits of having the control loops optimally tuned and it is therefore a pre-requisite for a high quality system to be able to accommodate APC not only as a function but also as a system suppliers’ core skill.  When optimally tuned loops are achieved in combination with optimized operator actions then the maximum benefits are realized, therefore the system must be able to accommodate both these features.  The effectiveness of the APC is measureable by the improvement in the statistical spread of product quality over time and for a range of operating conditions and feed stocks.  As the spread becomes narrower then the mean operating points can be moved to a point closer to the target levels, thereby minimizing energy usage and raw products wastage.  If the operator actions are also optimized then the thresholds can be reduced further.

Alarm management

In recent years the importance of effective alarm management has been recognized and structured solutions promoted by publications such as EEMUA 191 (Alarm Systems - A Guide to Design, Management and Procurement), which in one country has become government recommended practice.  A high quality automation system adopts these proven recommendations and provides the tools to optimize the alarm handling to ensure operators are not swamped with distracting alarms.  This is particularly important when large control and safety systems are integrated (such as refineries) due to the different demands on alarm and event discrimination and resolution.  A common integration problem is the inability of control systems to retain the high resolution timestamp information required by the safety systems, making rapid identification of trip initiators difficult, which leads to increased deferred production.

High quality automation systems accommodate the high resolution (down to 1 millisecond) safety events (without replacing them with a lower resolution control system timestamp) and make the order of incidence clearly visible whilst consolidating those events with the process control alarm list.  Some systems require external (and often 3rd party) alarm management packages which adds hardware and interfaces (sources for faults), or the consolidated list is only available at engineering stations.  In summary, high quality automation systems provide consolidation and clear visualization of alarms from all integrated and connected applications with facilities to prevent flooding and operator overloading.  Figure 2 shows the basis of alarm consolidation in the Yokogawa Centum VP operator station.

Figure 2 – Alarm consolidation and management

As described earlier, the inclusion of advanced features must be accompanied by the means to measure their contribution and effectiveness.  In the case of alarm management, the system must provide facilities to allow measurement of alarm and operator traffic in the system, and to quickly identify persistent alarms.   Visual representation of this KPI allows rapid identification of imbalances and quantities, which can be compared with reference profiles to quickly identify the nature of the operational deficiency.

Figure 3 – Analysis of alarms vs operator actions

An example of such analysis is shown in figure 3 where the upper and lower traces represent alarms and operator actions respectively.  In this example the balance is not optimal.

Adverse operations

It should not be forgotten that the refinery is not always running in optimal production mode, there will be times when adverse conditions and events will require the process to be interrupted and even shutdown.  This means that the automation solution has to include safety and protection systems which can be complex for some operations, particularly where both batch and continuous sequences are involved.  In emergency situations operator assistance may extend to automatic intervention, whereby the process is driven or restricted to predefined states if operator actions are not being effective, ultimately the process may be automatically put into a stable safe state by an integrated protection system.  Most automation systems can provide control and protection functions, however the measure of quality and efficiency arises from the level of integration of these functions whilst maintaining the necessary segregation to satisfy safety standards.  A high quality system allows the use of smart instrumentation for both control and safety functions with easy access to diagnostic information in a common maintenance environment without the need for excessive hardware and communications networks.  By this measure, should adverse conditions arise, the speed with which faults can be detected, compensated and corrected reduces deferred production from unnecessary shutdowns.

Most automation solutions providers claim to provide Integrated Control and Safety Solutions. The solutions may functionally appear the same between systems, however the high quality solution will rely on less ancillary equipment to gather and distribute diagnostic data or to provide the necessary interaction between critical and non-critical functions. For refining operations this interaction between control and safety functions is necessary to ensure efficient recovery of the process after a trip, especially nuisance trips during a sequential process.

Process diagnostic support

For optimal maintenance the automation equipment must naturally be reliable such as not to fail in the first place, achieved by embedded capabilities, but it should also be able to provide more than just system fault reporting and remote maintenance.  The inclusion of Process Diagnostics provides the means to predict and respond to fault conditions in the process interfaces, or even the process itself, without the need for human presence or manual intervention, for example the use of Impulse Line Blockage Detection/Clearance and valve Partial Stroke testing. Much has been written about such features, however in general terms a high quality system is based on a technology platform capable of accommodating these and other emerging features and functions easily and with minimal disruption to the running system.

Data vs information

Business decisions require information, and information requires data.  High Quality automation systems can provide huge amounts of data from all levels of the system, more data than can be realistically processed by the human owners and operators therefore the data must be transformed into useful information for the intended users.  Such data should be considered to be a business asset and needs to be manageable like any other asset.  The automation system should provide a reliable platform for this business asset and formulate the data to usable information by all relevant stakeholders in the refinery.

For example the refinery maintenance department may have traditionally relied on technical status based information for corrective maintenance and schedule based preventive maintenance, however the current automation technology generates efficiencies by providing Condition Based Maintenance and predictive failure reporting, minimizing the level of schedule based activities with corresponding cost reductions. In contrast, the refinery management team requires their information in the form of production figures, productivity and forecasts which also need to be available on the business network, though the data is derived from equipment connected to the control system network.  This highlights another value related issue very relevant to the system quality, namely system security.

Security

Security is becoming more predominant an issue for automation systems, as threat levels increase whilst the solutions become more aligned with Information Technology based “open” solutions, including wireless communications at the plant level.  Systems must be secure without being inaccessible by management, therefore a great deal of effort is expended by the system providers to embed protection and firewalls.  The effectiveness of these protection measures is due to a combination of the technology and the manufacturers’ commitment, and it is a continuous development process.  There have been demonstrations of how major automation suppliers systems could be compromised without the operator being aware.  In other cases the systems have been subjected to independent world leading security test houses and scored highly on security resilience.  As a value measure, this is a clear indication of automation system quality and should be a key value selection criterion.

Conclusion

High quality automation systems can be seen to be essential for refinery operations based on the attributes and performance indicators described, with “Quality” being mapped to system “Value” on a number of parameters summarized as follows:

• Operational Efficiency via Advanced Operator Assistance and APC
• Improved product consistency with narrower statistical distribution
• Energy and product savings by operating closer to boundaries
• Improved recipe changeover
• Capture of best operator practices
• Reduced operational risks
• Integrated protective functions
• Abnormal operation assistance to avoid unnecessary shutdowns
• Secure yet accessible data and information
• Reduced ownership costs
• Smart equipment support for Control, Safety and packaged plant
• Remote and Condition Based Maintenance
• Process diagnostics
• Holistic Evaluation
• System and Product Lifecycles
• Proven long term vendor commitment to reduce obsolescence
• Vendor adoption of emerging standards and methodologies
• Vendor commitment to R&D and alignment with end user aspirations

The High Quality Automation System is the enabling technology platform for the optimization of the core business objectives, for the lifecycle of the refinery.  The link between “low maintenance” and “operational efficiency” is clear though the “efficiency” differentiator is also heavily driven by operational factors to improve product consistency, allowing product quality to be achieved at operating levels closer to the quality boundary. This makes the automation system a critical element of the refinery business plan reinforcing the need to consider selection as a “Value” based holistic process.