Managing Process Plants for Failure

  • December 19, 2011
  • Feature
The Dilemma of Real-Time Optimization (RTO) and Advanced Process Control (APC)
December 2011
By Bill Lydon, Editor
Companies are looking for ways to improve efficiency and profits but the use of and Real-Time Optimization (RTO) including Advanced Process Control (APC) is still limited.   Why?
One argument is that RTO requires an investment without a guarantee of success. I find it interesting that companies with this attitude often are the ones that are willing to spend hundreds of thousands to hire high priced business consulting firms to analyze and explore a range of business improvements including, “streamlining operations” (translation = cut experienced people), and “strengthening the value-added role of purchasing” (translation = beat down costs). In addition, companies are busy doing “financial engineering” to increase shareholder value through realignment of corporate financial structures, strategic mergers, acquisitions, and alliances. One major business consulting firm states, “We use growth and financial-restructuring levers to help improve stagnant stock prices.”  However, there are some leadership companies that are leveraging real engineering using RTO to improve efficiencies for competitive advantage. These companies generally view RTO as a competitive weapon and will not openly discuss successes.
RTO and APC have been around for some time now and can improve plant operating efficiencies in a wide range of applications. So why is it only being used in a limited number of applications? In the past, the cost of computer processing power was a major barrier to using RTO.  This has changed dramatically.   RTO and APC are established technologies and offered by a number of suppliers.
Perspectives from Charles R. Cutler, PhD
Charles R. Cutler, PhD and recognized industry expert, provided an excellent background, update and professional opinion on the topic at ISA Automation Week 2011 (October 17–20, 2011).   Cutler holds a BS degree in Chemical Engineering from Lamar University and a Ph.D. in Chemical Engineering from the University of Houston. He worked for Shell Oil Company for 23 years in a variety of assignments in refineries, chemical plants, research, and central engineering. In 1984, he started his own company and was the CEO and president for 12 years until it was sold to Aspen Technology in 1996. Cutler currently spends most of his time with his new company where he is active in several technical areas including development work that has resulted in patents for methods of improving advanced control.  
In his presentation at ISA Automation Week, Cutler discussed how Real-Time Optimization (RTO) was met with great enthusiasm in the mid-1960s and gave way to frustration in the 1970s. The reason most of the early real-time optimization projects failed included computers that were slow/unreliable, hard to program software, and inadequate modeling tools. Another issue has been over zealous sales and marketing teams that communicated a minimized need for the number of high quality experienced engineers required to maintain the RTO system after it is installed. This is a common pattern when new technology is introduced.
Control Problems
Physical processes in many industries are non-linear due to a number of factors. In some cases, a process may have been initially linear and efficient but changes in a range of factors over time create unavoidable instability. Cutler stated the major opportunities are to use RTO to overcome operating problems where process equipment is not being operated for maximum profit.   For example, operators cannot determine optimal setpoints due to a number of factors including complex multi-input, multi-output relationships, operating constraints, nonlinear relationships, changing process dynamics, unmeasured disturbances, unknown relationships, frequently changing production targets, and incoming feedstock variability. To illustrate the need for advanced control, Cutler gave the example of a controller with 25 manipulated and 40 controlled variables, with only one limit on a variable, noting there are 6.5 * 1017 possible combinations of constraints.
Cutler asserts that RTO needs to be applied for companies to be competitive but it takes a shift in a company’s management, operations, and engineering thinking to make investments.   High quality experienced engineers are required to install and maintain these systems. The trend in most companies in the USA and Europe has been to reduce engineering staff to a minimum. The idea of committing engineers to maintaining a large system is not consistent with minimizing staff.  Cutler asserts that if management understood the amount of money they are leaving on the table, these engineers would be the very last place they reduced staff. The problem here is most of the people in senior management positions do not understand the potential. Unless the senior management of corporations is willing to add technical people and change the culture in their companies, advanced process control will not succeed in the long term and companies will continue to lose unrealized profits.
Cutler made another important point that models which are developed in the process of applying RTO become the repository of a company’s best technology and operating experience. 
Note: ISA Members can see the presentation by Charles R. Cutler, PhD and others presenters from ISA Automation Week 2011 by logging into the website
Thoughts & Observations
Using technology as a competitive weapon should be a fundamental management strategy to leverage knowledge. There needs to be cultural change to make this happen but, as Cutler points, out most of the people in senior management positions do not understand what goes on in their processes and the potential to be gained from better control.
A lot of time and energy is being spent on the consideration of migrating older control and automation systems to newer ones. While there is a time for this, a better return on investment in many cases may be to add RTO/APC.

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