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“In 1996, we rebuilt a large tunnel kiln used for firing ceramic products,” says Alan Dull, senior project engineer. “Over roughly an eight-year period, the ductwork had deteriorated. When we first started looking for new ductwork, we wanted a maintenance-free product with a 10-year minimum life and an 800?C application. We were also looking for resistance to chemical attack.”
Enter Danser Inc. and its Vacuduct® product, a metal-jacketed and vacuum-formed ceramic fiber insulation. “We had worked with Danser numerous times over the past 20 years,” says Dull. “Additionally, Swindell Dressler, the company that supplied the tunnel kiln, had used Danser as ducting insulation subcontractors for years. So we were familiar with them and confident about their level of work.”
Getting StartedAccording to Vic Davis, Danser’s general manager, each Vacuduct project is different, but having complete measurements and drawings is the most important first step. The ductwork for Corning’s tunnel kiln has a 30-in. inside diameter and involves multiple connections—so accuracy was vital.
“The vacuum-formed ductwork is not that easily altered in the field, so we want to make sure that everything’s measured properly,” explains Davis. “Not only is the duct more difficult to alter, but precision also saves time because we install everything rather quickly.”
While the company’s team can visit sites to take measurements prior to installation, most of the ductwork is manufactured according to customer-supplied drawings. “[For this job,] Swindell Dressler designed the routing of the ductwork,” says Davis. “They gave us the drawings, and then we took those drawings and made our shop fittings match where they wanted the duct to go.”
In addition, Corning also had a new exhaust system installed. For this portion of the project, Danser handled the drawings and design. “We gave Danser a sketch of the off-takes and exhaust system we wanted fabricated,” explains Dull. “And they came down and took field measurements, then went back to their office and designed the system.”
InstallationFrom shutting a kiln down, cooling it and then heating it back to temperature, installing new ductwork can be an extremely time- and cost-intensive project. “Depending on what type of kiln it is, it might take three days to cool down and three days to bring it back up—and that can mean a lot of wasted fuel and product,” says Davis. Danser’s installation crew has discovered a way to eliminate those problems by installing the ductwork while the kiln is still in operation.
“We make up all the ductwork, and [the manufacturer] temporarily shuts down a fan where we’re going to replace the ductwork or maybe back-drafts the kiln so that the heat, instead of going up, is being pulled back down through the kiln,” explains Davis. “Then we’ll take the ductwork off, put [the Vacuduct lining] in and get [the kiln] back up and going. They don’t lose any time, or product.” Accuracy in measurement and design plays an even more important role in this type of installation. “This really is hot work,” laughs Davis. “We have to make sure everything fits before we start pulling ductwork off!”
Says Dull, “We couldn’t take the kilns down to install new ductwork—we had to maintain operation. Danser installed it with the kiln still hot, going through a 500?C-plus crown to make the off-takes. This was a great benefit to us because we didn’t have to shut down our operations to have the new ductwork installed. That’s one of the reasons we decided to go with Danser on this and other projects—their field installation crew is absolutely fantastic. They were also able to accomplish the work in a relatively short period of time—they worked around the clock, 24 hours a day for three or four days to get the system installed. It probably would have taken a week and a half or more without that level of dedication.”
Positive Results“As far as we know, Vacuduct has performed to our expectations,” says Dull. “We have not gone back in and analyzed the condition of the ducts, but all indications are that they’re okay. We have no hot spots on the outside.”
And the Vacuduct installation has done more for Corning than just solve the ductwork problem. “The design of the new ductwork has enabled us to process materials that we had not previously been able to, allowing us to expand our product line,” says Dull. “Danser designed around existing constraints to put the equipment in place in very confined areas under adverse conditions. Without this level of customization, we would not have been able to expand our product line.”
For More InformationFor more information about Corning, Inc., contact the company at One Riverfront Plaza, Corning, NY 14831; (607) 974-9000; or visit www.corning.com.
For more information about Vacuduct, contact Danser Inc. at Route 50, Murphytown Rd., P.O. Box 4098, Parkersburg, WV 26104; (304) 679-3666; fax (304) 679-3354; e-mail email@example.com; or visit www.vacuduct.com. More information about Vacuduct can also be found in the article “What’s Inside Your Ducts,” CI February 2001, pp. 45-48.