Process Puzzler: Master a Musty Mess

Readers suggest how to deal with a contamination source.

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What is the moisture content of the seeds, i.e., the grain? A trip to the library showed that seeds protect a layer of moisture inside a resin barrier. I theorized that grinding released the moisture. So, I had the seeds ground and then measured the moisture in the trapped air in the container. The psychrometer jumped off the scale. In my report I recommended insulation and heat tracing. Because the duct was exposed to cold ambient air in its climb to the sixth floor, I recommended steam tracing rather than electric because of the heat demand. Also, electric tracing is four to six times more expensive to operate; actual costs depend on the source of electricity and the source of steam.
Dirk Willard, senior process engineer
Swenson Technologies, Monee, Ill.


Our company has been taken over. The new management wants to improve our energy efficiency and accuracy of our material balance (see Figure 1). They’d like to bring the balance to ±1% accuracy. Several flow meters yield questionable data: 1) an orifice meter measuring a wet gas (A in the figure); a vortex shedding meter with a tendency for fouling (B); a meter with a competing recycle line (C); a Coriolis meter with a gas problem (D); a vortex meter with startup difficulties because of gas entrainment (E); a Coriolis meter that measures product successfully (F); and a venturi tube meter that occasionally suffers plugged taps (G). The turndown on the process is about 3:1. How can we reduce our energy consumption and tighten our material balance?

Send us your comments, suggestions or solutions for this question by October 9, 2009. We’ll include as many of them as possible in the November 2009 issue and all on Send visuals — a sketch is fine. E-mail us at or mail to Process Puzzler, Chemical Processing, 555 W. Pierce Road, Suite 301, Itasca, IL 60143. Fax: (630) 467-1120. Please include your name, title, location and company affiliation in the response.

And, of course, if you have a process problem you’d like to pose to our readers, send it along and we’ll be pleased to consider it for publication.

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