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Flushless Seal Boosts Uptime for Ethanol Producer

Tue, 09/09/2003 - 10:50am
The Abengoa Bioenergy Corp. ethanol fuel plant in York, NE, is one of three U.S. facilities formerly operated by Wichita-based High Plains Corp. that produces 85 million gallons of ethanol a year. It earns $42,000,000 annually and uses more than 19 million bushels of local grain.

That type of demand requires that production run at the height of efficiency. And while the plant's harsh environment was expected to take a toll on processing equipment, a one-day life-span for a crucial seal was unacceptable.

"Most of our seals last 60 to 120 days before failing," says Russell Konwinski, Abengoa's maintenance manager and an eight-year company veteran. "But one seal lasted only one day before leaking. It was obvious that we needed something much more reliable."

While the poor-performing seal was a problem, the scenario was complicated by the physical product created at the facility: a sticky, yellow corn mash containing 30% to 35% solids that typically required double seals. But installing a pressurized seal support system that would extend seal life was expensive and time consuming. The potential to dilute the process fluid with barrier water escaping the seal added complications.

In spring 2002, Konwinski and pump technician Russell Shockey learned about the John Crane Type 5870 flushless single-cartridge seal. According to the Morton Grove, IL-based company, the key selling point of the 5870 single-seal is its flushless attribute and its ability to accept pump cavitations, dry running and air-bind operation. To Konwinski and Shockey, it seemed a cost-effective solution for Abengoa because the seal needed no external seal-support system, tank reservoir or barrier fluid. Moreover, it had the potential to be more effective: The open-profile, abrasive-resistant sealing faces positioned near the impeller would allow maximum cool-running and clog-free performance. A large O-ring would prevent process-fluid fibers or solids from causing seal hang-ups. Konwinski knew that external-seal water-flush support burdens a system with extra liquid that must later be removed to create a final product. The 5870 seal can maintain better control and use less water, which was another route to lower operating costs.

Since Abengoa was in the process of changing pump styles, Konwinski says it made sense to incorporate the new seal. A complete pump system, including the factory preassembled, single-cartridge seal design, was installed in a few hours, tested and in service for a trouble-free startup. Following this, two more seals were installed on larger pumps in July and November. According to Konwinski, all have incorporated the grease-style quench and are exceeding performance expectations.

From a cost standpoint, Konwinski says the seal quickly paid for itself. "The cost of a double seal, as well as the cost and manpower associated with a flush system quickly adds up," he says. "We are pleased with this solution and are happy to report that everything advertised about the product is true." The seal has reduced maintenance and downtime, he says, which Shockey believes is a key benefit. "Now we can install a seal and not have to support it with maintenance except for the grease quench," he says.

Additionally, the new seals have reduced product cost since the company is not consistently ordering new seals. Abengoa also will not have to purchase new pumps or resize existing pumps due to under-performing seals.

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