Essroc, formerly Coplay Cement, is a wet-process cement plant in Frederick, Md., that produces 350,000 to 400,000 tons of cement annually using two 400-foot rotary cement kilns.
Dust is produced in these kilns at a rate of 120 tons during a normal, 24-hour period, and this dust must be removed from the kiln’s exhaust gases. A portion of the dust is collected and sold for industry and agriculture, but the majority of it is recycled through a process called insufflation, transforming it into product. The insufflation rate can be varied by the cement control operator to match the chemistry of the cement in the kiln.
The original pneumatic conveying lines were plagued by constant plugging and surging problems. Upgrading the systems pumps and compressors didn’t eliminate plugging in the system’s long-radius sweep elbows, and elbow wear-through became a problem as well. Then the plant gave 5-inch, cast-iron Smart Elbow deflection elbows a try.
“This eliminated most of the remaining line-plugging problems,” said Ken Gillespie, Essroc process engineer. “I can only recall perhaps two or three plugging problems for the last couple of years. The wear problem was eliminated completely. As far as I can tell, none of the Smart Elbow units has been replaced for any reason.”
The system plugs now only when very high insufflation rates are chosen, Gillespie said, adding that the elimination of wear and downtime have resulted in substantial savings for the company.
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