I got a sick feeling in my stomach every time I walked by our extractor feed pump. Fortunately, there were no safety hazards or other onerous situations waiting to occur. It just irked me that the pump was operating at full speed with its flow being throttled by a control valve located about one meter above the pump. Had the valve been located up in the structure (as was the case of its neighboring pumps), I would not have been so upset. But there it was … near the edge of the structure in full view for all to see. Maybe I’m sensitive, but all I could see was the electrical meter spinning unnecessarily. It took me years to change this, but let’s start at the beginning.
In general, considering the overall problem holistically and combining various technologies to achieve superior results interests me. If you think about it, this is what we do every time we apply instrumentation to a process. In my mind, it was egregiously wasteful to operate a pump at full speed to generate hydraulic energy only to dissipate that hydraulic energy across a control valve – especially when the control valve was located in plain sight at the pump discharge.
This practice was clearly wasteful and it would be much more efficient to control flow by reducing the speed of the pump and eliminating the control valve. Predicting the actual waste involved in this practice required a working knowledge of many technologies to include electrical, instrumentation, chemical, hydraulics, pumps, energy, electrical distribution, utilities, and the like. There were no books written that analyzed each aspect of the application of variable-speed drives in a practical manner. Further, my professional experience was limited to a few years, and I had not yet written any books or technical articles, nor had any teaching or expert witness experience.
Next month I will describe the road taken to show the amount of waste associated with this operation.
David W. Spitzer is a regular contributor to Flow Control with more than 35 years of experience in specifying, building, installing, startup, troubleshooting, and teaching process control instrumentation. Mr. Spitzer has written over 10 books and 150 technical articles about instrumentation and process control, including the popular “Consumer Guide” series that compares flowmeters by supplier. Mr. Spitzer is a principal in Spitzer and Boyes LLC, offering engineering, expert witness, development, marketing, and distribution consulting for manufacturing and automation companies. He can be reached at 845 623-1830.
