Monthly Archive: September 2009

Sep
25

Exceptional Opportunities in Process Control – Live Process Flow Diagrams

The first document you have on a project is typically a process flow diagram (PFD). The PFD defines the process. It is the ultimate source of information and sets the plant performance and design. It is interesting to me that we really don’t know how well existing operations match the PFD. When I have posed …

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Sep
15

Exceptional Opportunities in Process Control – New Sensor and Valve Technologies

I spent the first 7 years of my career in instrument design and construction. After being responsible for the calibration, installation, and commissioning of instruments for a half dozen plants in the 1970s, I became painfully aware that the actual performance of the measurements and control valves was largely unknown. These were the days before …

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Sep
09

Exceptional Opportunities in Process Control – Sample Time

I hesitated at first to include sample time as one of the exceptional opportunities in process control because in most loops it is not issue. Then I realized I should give my perspective on the effect of sample time for the following reasons: (1) Since we live in a digital world, sampled data is the …

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Sep
02

Exceptional Opportunities in Process Control – Integrating Process Tuning and Performance

Unlike self-regulating processes that will line at a steady state after disturbances have died out, integrating processes will ramp until a physical limit is hit. The ramping response is caused by the lack of negative feedback (e.g. self-regulation) in the process as defined in Advanced Application Note 4. In other words an increase in the …

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