Nothing Like the Real Thing

Sept. 16, 2003

The most fun we have developing content for this magazine happens when we find fellow chemical process plant comrades who are willing to talk about the ways they're making newer technologies work for them.

I ran into more examples of that recently at Perspectives 2003, a day-and-a-half conference anchored around hanging out with users of Coriolis flowmeters, and hosted by Micro Motion.

Coriolis? You say you haven't run into many application examples of Coriolis use?

Actually, Coriolis technology adoption is doing pretty well in the CPI and the conference provided some nice examples of it. Here's one of the best.

Donald Dunn is senior IEA & controls engineer at Equistar Chemicals in Channelview, Texas. He's been struggling to accurately control sulfuric acid flows in a three-stage alkylation process.

Produced as an alternative to MTBE for gasoline, alkylate is the product of reacting light olefins with isobutane in the presence of sulfuric acid. Feed stock impurities set off competing reactions that produce acid-solubles. This requires adding fresh acid continuously to the reaction.

"The key is accurate acid use," said Dunn. "Our 3-in. mag meter didn't provide flow control at [required] pipe velocities below 1 ft./sec., so acid use erred on the side of overuse." If acid strength falls below 88 percent, polymerization reactions overwhelm the process and it becomes an "acid runaway." Overuse meant acid strength leaving the third stage was around 94 percent instead of an ideal 88 percent to 89 percent. This is a costly safeguard.

"We finally tried a 3-in. Coriolis meter, which gave us increased turndown, a low pressure drop, and online density monitoring," said Dunn. "That meant we could infer acid strength directly from the density readings."

Continuous density reading,"that was big break. Because acid strength was now always known, the additions were controlled well enough to drop the exit stream acid concentration to 89 percent to 90 percent. "The cost savings on acid alone paid for the entire project in less than 10 months, and the savings can exceed $1 million annually," reported Dunn. He's also seen better yields since the process can run a bit slower and not prematurely push hydrocarbs through.

All in all, a nice example of leveraging the multivariable measurement benefits from Coriolis meter technology.

Changing gears, I can't let this month's column get away before I introduce you to Agnes Shanley, our new managing editor.

Agnes comes to us with a solid record of experience and involvement in our industry. With a B.S. in Chemistry and Life Sciences, she's well schooled in the fundamentals. For more than 15 years she has reported on, analyzed and written about all the major CPI issues of the times.

She debuts this month in Reaction (pg. 9), with no-nonsense look at the congressional wheel spinning that continues to thwart workable plant security legislation.

By Joe Feeley, publisher and editor in chief

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