PLCs & PACs / Optimization / Asset Management

The New Era in Advanced Process Control

Source: AspenTech

By Robert Golightly, Sr. Manager, Manufacturing at AspenTech

Sep 05, 2014

Refineries and chemical companies are under constant pressure to improve throughput, save energy, meet operational constraints and improve time management Advanced technology delivers the most effective solutions for any process task or problem. As modern process plants become more complex Advanced Process Control (APC), in addition to basic process controls, is needed to meet the increasingly complex operational targets and customer demands.

Therefore, by optimizing their assets using advanced technology, industry leaders can expect to maximize process profitability and see a greater return on their investments. So, how can engineers ensure they have the right tools to better control and shape the economics of APC to meet business objectives?

Today, APC engineers need to exert tighter control of operations in order to squeeze out more production at lower cost from complex and demanding processes. Standard APC applications are typically built with an underlying assumption that the model developed by the engineer will always be accurate and properly structured. However, as process plant performance and economic objectives change, this may cease to be the case as the behavior of the process changes over time. Although a controller may be accurate enough when implemented, at some point in the future it may not be, so the aim should be to automatically detect this occurrence and correct it on a continuous basis.

Also Read "Advanced Process Control Ain't Easy"

When issues with model fidelity are detected, the tuning of the controller should also change to mitigate the potential negative impact. So, it is important that the engineer is equipped with valuable insight into process behavior and understanding of process characteristics.

Ultimately, it is the ability to shape the properties of the controller across testing, operation, maintenance and enhancement phases that will improve benefits, reduce the cost of ownership and mitigate risks associated with model accuracy issues.

The smart software

AspenTech’s Aspen DMCplus® software has been the industry standard for advanced process control software. Now, with a completely re-designed modeling environment and the introduction of AspenTech’s Adaptive Process Control solution, the process industries have a powerful new tool available to manage their operation with greater control that will deliver greater operational profitability – Aspen DMC3 software. This technology provides a complete range of economic trade-offs for managing step testing and model construction. Essentially, that eliminates the need to approach APC maintenance as a project and creates a continuous background process of assessing model quality, collecting current data and generating new models as the behaviour of the plant changes over time. The Adaptive Process Control initiative was born from a need to address the current problems associated with building and maintaining control applications. Smart software can detect, isolate and correct problems without increasing the burden on engineering staff. The key advantages of Adaptive Process Control capability over traditional sustained value approaches incorporate features that ensures the controller model is continually analyzed for accuracy, poorly performing areas of the model are identified, non-disruptive background testing collects new process data while the unit is being optimized and new data are monitored in real time and bad data are automatically identified and removed. By making it easier to generate data, manage step tests and produce results, APC becomes more accessible and efficient.

There is a crucial difference between the traditional approach to controller maintenance (sustained value) and Adaptive Process Control capability. With sustained value, revamping the controller is typically carried out as part of a lengthy and costly project. Under Adaptive Process Control, however, the clever controller is modified over time in a background process that is not disruptive to plant operations. Adaptive Process Control improves long-term profitability by reducing process variability and allows plants to be operated optimally. Refiners and chemical companies have seen great value returns in product yield improvement and minimized energy costs with financial pay-back within short time periods. For existing controllers, keeping applications running at peak performance is a big challenge. We are all aware that quicker and more efficient control projects improve the return on investment and, therefore, Adaptive Process Control opens up new opportunities to implement APC with this clever approach.

A new era

So what’s new? Today, the technology game has been taken to a new level. Aspen DMC3 software combines industry leading Aspen DMCplus technology with the most innovative tools for building and maintaining controllers – all in one place. This cutting-edge software provides the control engineer with the ability to modify the behavior of the controller based on the lifecycle needs (i.e. lifecycle needs defined by changing process plant performance and economic objectives). The new gain constrained model identification in this software leverages process knowledge to create more effective model predictive control applications.

Innovation and economics go hand in hand. On the one hand Aspen DMC3’s Adaptive Process Control solution provides a complete range of economic trade-offs for managing step testing and model construction. On the other hand, the robustness feature of this software provides the same ability to shape the performance of the controller when in optimizing control mode. By setting the robustness factor, the controller aggressiveness can be set by the engineer to mitigate the risk of poor model conditioning. Binary choices are replaced with a continuously variable scale giving fine control over the technical and economic trade-offs involved in APC. The benefits to companies are also significant and include better control to shape the economics of APC solutions to continuously meet changing business objectives. In addition, users can now shape the behavior of the controller during testing, model construction and deployment phases.

More power to the pocket

Operating a process with greater control increases efficiency and safety to improve product quality. Robust control provides risk mitigation against poor model conditioning. Innovative APC software allows plants to operate at the highest possible throughputs, maximize yield of highest value products and perform at the optimum energy usage possible.

Aspen DMC3 software marks a new era in APC technology. By mitigating model errors and improving the performance of control over time, this groundbreaking innovation optimizes the production process, eliminates waste and reduces the overall cost in the manufacturing process.

With this latest APC technology, implementation and maintenance of APC is no longer an arduous project, but more of a continuous program of improvement. The bottom line is that with this APC innovation, companies now have truly robust control and ‘cost-to-payback’ return on investment with dramatic and uplifting results.