Dow DERAKANE NEWS
The proper waste containment system is a vital part of the power industry, particularly coal plants that deal with various types of toxic and corrosive waste streams
In the past, lignite-burning power plants often used dirt-lined or clay-based pits to store wastes such as carbon-containing acids, or inorganic acids and caustics. However, such pits are now believed to provide insufficient protection for corrosive applications.
Therefore, Houston Light and Power (HL&P) now installs fiberglass-lined concrete storage basins for corrosive waste applications, according to Dale Wright, lead engineer for the utility’s Jewett, Texas plant.
One of the basins is an organic retention pond that contains mostly organic cleaning waste, which is then pumped out for onsite disposal according to Wright. The largest pond is for inorganics that contain some metal cleaning waste. Prior to being discharged, the inorganics are circulated through a waste treatment system. There is also a chemical equalization basin for demineralizer wastes and other chemicals wastes, explains Wright.
HL&P’s Limestone plant in Jewett, TX, specified storage basins lined with fiberglass after a successful application at the Parish plant in Thompson, TX.
“Based on our experience at the Parish power plant, we believe fiberglass-lined concrete basins are the best suited for this type of application,” says Lewis Cathey, a project specialist for HL&P. The fabricator for the basins on both projects was Wil-Cor, Inc., of Houston. Specifications for the storage basins called for either a bisphenol resin or a vinyl ester resin to be used. “The vinyl ester resin was selected for chemical resistance, elongation, and workability properties in elevated temperatures. The surface temperatures sometimes exceeded 100 F at the time of construction,” according to Fred Wilson, president of Wil-Cor. “We needed a quality dependable resin.”
According to Wilson, there are three basins lined with Derakane, 411-45 Vinyl Ester Resin, at the Jewett plant, constructed with more than 150,000ft2 of concrete. Expansion joints known as Omega® joints, developed for concrete expansion and contraction by Wil-Cor were used for this project. “The design of the FRP Omega joint was developed to solve the problem of water and acid migration through existing expansion joints, as well as construction of the concrete in excess of one inch due to temperature change,” explains Wilson.
Today, as the Environmental Protection Agency attempts to monitor the storage of corrosive liquids, the fiberglass-lined basins, that have been in service since 1986, have proven “worthwhile from both price and safety standpoint,” says Wilson.
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