Improving Control Performance

Today is the final day of the 2018 Emerson Exchange conference. The last session I’m attending is on Control Performance with Emerson’s James Beall, Courtney (Eddie) Lane, Dirk Thiele and Aspentech’s Alex Kalafatis.

Control Performance Experts Panel at Emerson Exchange

After the panel introduced themselves, Dirk opened the panel with a poll question, “How would you rate the overall control performance in your plant?” More than 50% indicated that it needed improvements with a third saying it’s good enough. A small sliver said it was very good.

Accenture and ARC Advisory group consider advanced control and analytics are two technology areas driving digital transformations among manufacturers. The biggest area holding these manufacturers back are cybersecurity considerations.

Dirk noted that around 50% of the control loops underperform their capability and advanced process control is underutilized in many areas. Control performance metrics will be integrated into the Guardian Portal for users of Emerson control and safety systems.

Eddie discussed procedure automation with operational procedures and procedure automation. He likened them to batch controls but are administrative controls for continuous processes. Examples exclude startup procedures, manual inputs into the process. They capture the best practices in an operation to improve situational awareness, unify the understanding of how these procedures are performed, keep process knowledge in employee turnaround, enforce best practices, reduce human error, and realizing performance gains from closing the gap between average and best performance.

The ISA106 model includes three subdomains: requirements, implementation and map to physical process. It defines the concept of a task, or something that has a command, performs the command, and verifies that the command has been performed. An implementation module implements these tasks in the proper sequence.

To perform procedure automation, start with defining and capturing process, procedures, policies, safety considerations and personnel tasks. Interpret and design the procedures. Implement and test the designs through simulated testing, and then operate and audit the performance of the online procedures.

Eddie shared an example of a procedure in a coker drum. The site was looking for better situational awareness of the manual operation. Operators were prompted to perform tasks such as opening manual valves or checking various operating parameters as they were swapping operations between drums.

ISA106 defines state-based control that has inputs, transition functions, the current state, an output function, and outputs. It is one of the best techniques to have operations match the documentation of what should occur. For example, a pump may have the states of offline, shutdown, startup and running. State-based procedures can improve startups, overall throughput, operator interventions required and alarm annunciations. It’s best to put the state-based control within the control system if possible.

James next spoke about advanced regulatory control and embedded model predictive control (MPC). This is usually one of the projects that can have the highest return on investment (ROI). There are benefits to have in throughput, energy costs, product inventories, quality variations and equipment availability.

James illustrated a lube refinery 2-day project that returned $245K per year and a 10-day payback. It included adding some feedforward control, gain scheduling and MPC.

Some of the technologies in the DeltaV system to support control performance include Intelligent Controller Tuning (DeltaV InSight), Adaptive Control (DeltaV Adapt) and MPC (DeltaV Predict), Neural Networks (DeltaV Neural), and Fuzzy Logic (DeltaV Fuzzy) all with process model calculations as a base level feed. James shared a trick where one plant ran DeltaV InSight while the plant was starting up to learn the dynamics of the loops as operators made changes to the control loops during the startup process.

PID has many advanced features including feedforward, dynamic reset limits, wireless PIDPlus blocks, and more. James next spoke about embedded MPC with several examples that had hundreds of thousands of dollars in return on investment from a few-week project. Examples were in steam recovery, distillation columns, compressor controls and cracking furnaces. Good applications include constraint override, deadtime compensation, and disturbance rejection.

Alex next came up to define advanced process control (APC) as controlling based upon a model of the process. There can be so many interacting variables that regulatory control cannot reach optimal operational performance. He noted that the 3rd generation of dynamic matrix control (DMC), adaptive control has been added to help maintain the benefits delivered by advanced control over time by recognizing changes in the process that need to cause adjustments in the model.

For more on advanced process control and the consultants who can work with you to assess, apply and quantify the benefits visit the DeltaV Advanced Control and Operational Certainty areas of Emerson.com.