As previously stated, modulating flow using a variable speed drive to vary pump speed is more energy efficient than installing a control valve on the pump discharge. In a control valve installation, the pump generates hydraulic pressure, some of which is dissipated across a restriction (the control valve) to manipulate flow.
click for more...
Last month I suggested the hypothesis that liquid ammonia enters the unit with bubbles, causing the liquid ammonia ultrasonic flowmeter to break its ultrasonic circuit, incorrectly measure zero flow, and (in turn) cause the reactor to scram (shut down). Installing a section of jacketed pipe to cool the liquid ammonia upstream of the flowmeter reduced the number of scrams substantially.
click for more...
In addition to over 35 years of experience as an instrument user, consultant, and expert witness, David W Spitzer has written over 10 books and 250 articles about flow measurement, level measurement, instrumentation, and process control. David (with Walt Boyes) is the author of seven Consumer Guides to various industrial flow and level technologies. David teaches his flow measurement seminars in both English and Portuguese.
Spitzer and Boyes, LLC publishes the Industrial Automation INSIDER that is an independent subscription newsletter for industrial automation and process control system users, installers and suppliers world-wide, giving a monthly update on the continuing evolution, development and convergence of automation technologies.
Spitzer and Boyes, LLC provides engineering, technical writing, training seminars, strategic marketing consulting, distribution consulting, and expert witness services worldwide, and can be contacted at +1.845.623.1830 or www.spitzerandboyes.com.