The operator is by far the most important person in the control room having the most intimate knowledge and “hands on” experience with the process. Engineers who are most successful with process improvements realize they need to sit with and observe what operators are doing to deal with a variety of situations. Process engineers tend to recognize this need more than automation engineers. Improvements in operator interfaces, alarms, measurements, valves, and control systems are best accomplished by a synergy of knowledge gained by meetings between research, design, support, maintenance and operations where each talk about what they think are problems and opportunities. ISA Standards and Virtual Plants can provide a mutual understanding in these discussions.
The most successful process control improvement initiative at Monsanto and Solutia used such discussions with some preparatory work on what the process is actually doing and capable of doing. An opportunity sizing that detailed gaps between current and potential performance estimated by identifying the best performance found from cost sheets and from a design of experiments (DOE) most often done by a virtual plant due to increasingly greater limitations to such experimentation in an actual plant. After completion of the opportunity sizing, a one or two day opportunity assessment was held led by a process engineer with input sought and given by operations, accounting and management, marketing, maintenance, field and lab analyzer specialists, instrument and electrical engineers, and process control engineers. Marketing provided the perspective and details on how the demand and value of different products is expected to change. This knowledge was crucial for effectively estimating the benefits from increases in process flexibility and capacity. Opportunities for procedure automation and plantwide ratio control making the transition from one product to another faster and more efficient were consequently identified. Agreement was sought and often reached on the percentage of each gap that could be eliminated by potential PCI proposed and discussed during the meeting. A rough estimate of the cost and time required for each PCI implementation was also listed. The ones with the least cost and time requirements were noted as “Quick Hits”. To take advantage of the knowledge and enthusiasm and momentum, the “Quick Hits” were usually started immediately after the meeting or the following week.
Synergy can be maximized by exploring a wide spectrum of scenarios in a virtual plant that can run faster than real time and discussed in training sessions. Every engineer, scientist technician, and operator should be involved. If necessary this can be done at luncheons. Any resulting Webinar should be recorded including discussions. See the Control article “Virtual Plant Virtuosity” and ISA Mentor Program Webinar Recordings for this and much more in terms of gaining and using operational, process and automation system knowledge.
Webinar recordings should focus on the level of understanding needed and achievable in the plant and not what a supplier would like to promote. The ability of operators to learn the essential aspects and principles of process, equipment, and automation system performance should not be underestimated. We want to ensure the operator knows exactly and quickly what is happening being able to get at the root cause of a problem preemptively preventing poor process performance and SIS activation. Operators need to be aware of the severe adverse effect of deadtime. Fortunately, operators want to learn!
Finding the real causes of potential abnormal situations is critical for improving HMI, alarm systems, engineering, maintenance and operations. Ideally there should be a single alarm of elevated importance identifying the root cause (e.g., state based alarm) and the operator should be able in HMI to readily investigate conditions associated with root cause. Maintenance should be able to know what mechanical or automation component to repair or replace. Engineering should design procedure automation (state based control) to automatically deal with the abnormal situation.
Often the very first abnormal measurement is an indication of root cause. However, the abnormal condition should be upstream and the measurement of the abnormal condition should be faster than the measurement of other problems that occur as a consequence or coincidence. This is a particular concern for temperature because thermowells lags can be 10 to 100 seconds depending upon fit and velocity. For pH, the electrode lags can range from 5 to 200 seconds depending upon glass age, dehydration, fouling and velocity. There is also the deadtime associated with any transportation delay to the sensor. Finally, an output correlated with an input is not necessarily a cause and effect relationship. I find that process analysis and some form of a fault tree diagram and investigating relevant scenarios in a virtual plant as most useful.
Sharing useful knowledge is the biggest obstacle to success. The biggest obstacle can become the biggest achievement.
