F. Greg Shinskey is a legend in the field of process control. His writings and teachings have helped thousands of control engineers establish better control over the process. John Gerry, president and founder of ExperTune, credits Shinskey for core technology in ProcessApex, the new unit optimization software release from ExperTune. "We have worked closely with Greg for years. His distillation control knowledge is incredibly deep, and we have worked very hard to capture that knowledge in software form," Gerry says.
Shinskey's mark on the ProcessApex software is apparent. In his book, Distillation Control, Shinskey offers advice for the most efficient ways to control column compositions. In ProcessApex, the software serves up the appropriate set of Shinskey's equations and advice as recommendations for the best control strategy.
ProcessApex provides diagnostics and advice for unit operation improvement by combining real-time metrics with Shinskey's process control knowledge. The latest version of ProcessApex allows users to track, benchmark and manage the performance of distillation columns using real-time data from the control system and Shinskey's equations.
With its intuitive web-based interface, ProcessApex builds on the strength of ExperTune's PlantTriage Control Loop Monitoring software—the clear presentation of performance data directly from real-time sources. It then adds the capability to track performance in pure economic terms, and to benchmark the performance between similar distillation columns company-wide. Both technical and business-related performance are measured, including metrics such as yield, efficiency, specific energy costs, material balance, energy balance and opportunity gaps.
The opportunity gap assessments help drive column efficiency. The opportunity gap is, in effect, a suggested setpoint change for the process. ProcessApex determines this gap by looking at the real-time control performance of the column, comparing performance variables to operating specifications and reporting the expected economic value of making the change.
ProcessApex also makes use of ExperTune's process modeling capabilities by providing a model of column performance, in the form of a relative gain array, showing the relationships between the various parts of the column. This information is useful for process understanding and can lead to efficient design of more complex control strategies.
Benchmarking allows comparisons between columns or between sites. ProcessApex allows three distinctly different benchmarking approaches—benchmarking a column against its own performance over time; against similar columns under current operating conditions; and against similar columns over time.
One innovative display in ProcessApex is the "bubble chart" used to show more complex performance relationships. For example, to determine where to add capacity, use a bubble chart showing unit cost, excess capacity and column throughput. The column with the lowest cost, highest throughput and just enough excess capacity is probably the right one for the job. Rather than commission a complex engineering study, process engineers can quickly take a look at the bubble chart.
The new distillation capability starts with real-time evaluation of material and energy balance. Tolerances for balance closure can be adjusted based on the historical performance of the individual column.
ProcessApex requires minimal configuration. George Buckbee, vice president of product development at ExperTune, says, "ProcessApex effectively adds context to the flood of DCS data, so users can focus on one or two critical issues, rather than scanning hundreds of data points."
At a time when many companies are suffering from a loss of technical mastery, ExperTune says it's found a way to bring a world-class technical master into plants worldwide.