How Can We Better Control an Exotherm?


A reader asks, "We have to hold tight temperature control on a highly exothermic suspension polymerization process in order to maximize reaction rates. We tried using PID on the catalyst flow, but temperature fluctuation was too high. We added PID control to the cooling water, and can now control the temperature within 5C, but now the batch time is too long. What can we do to achieve tighter control on this kind of process?"

This is our second edition of Process Puzzler, the department we introduced last month for readers who are wrestling with a particular process problem or question and need expert advice.

Any question or problem related to manufacturing and process operations in a chemical plant is fair game. Send it to us. We'll print it here, post it on our Web site, and ask readers to help by sending in answers and solutions.

We're counting on you, and on the knowledge and experience of the Chemical Processing community, to make today's toughest process and equipment problems disappear. Answer the call of "comrades in need" with solutions, suggestions, anecdotes of past experiences, and whatever wisdom you can share. You may need help from your peers when you meet with a thorny problem or question in the future.

Answers to this month's question will appear in the October issue. The question we posed in July will be answered in September.


Send us your comments, suggestions, or solutions for this question. We'll include as many of them as possible in the October 2003 issue and post all of them on our Web site. Send visuals, too -- a sketch is fine. E-mail us at or mail to ProcessPuzzler, Chemical Processing, 555 W. Pierce Rd., Suite 301, Itasca, IL 60143. Fax: (630) 467-1120.

Please include your company, location, and title in the response.

And, of course, if you have a process problem you'd like to pose to readers, send it along and we'll include it as soon as possible.

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