Crack in Boiler Shuts Down Wisconsin Power Plant

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Researched by Industrial Info Resources (Sugar Land, Texas). The Oak Creek Power Plant (located in Oak Creek, Wisconsin), owned by We Energies, a subsidiary of Wisconsin Energy Corporation (NYSE:WEC), shutdown a 318 megawatt coal-fired Unit 07 on March 18, 2007, due to a major fracture in the main reheat boiler header.

Plant officials have stated that they believe there are various factors as to why the fracture occurred. Mechanical erosion, along with chemical and thermal wear due to the loss of some refractory material, are part of the reason. Oak Creek also stated that previous tube leaks deemed non-critical did not force the unit offline.

Officials are saying that over a period of time thermal shock from rapid temperature changes in the header could result in cracking, because the crack could widen during cool down and expand when heated. When too much expansion occurs, blown tubes are subject to deterioration and cracking develops.

Oak Creek power plant officials acknowledge these problems are possible causes for the shutdown. In addition several of the side boiler tubes, which provide steam flow into the boiler, had become separated and weak, causing a breakdown of heat release. These tubes, when installed are usually attached as two in one, but had split and become separated.

Plant officials stated that before making repairs on the crack they will have to replace quite a few boiler tubes, which would take about one to two months. The plant will deal with the crack once the tubes are repaired. July is the projected return date for the unit. Estimated repair costs were still speculative due to the preliminary nature of the maintenance evaluation.

The station began operation in 1959 and has five units with a combined generating capacity of 1,153 megawatts. The plant currently consists of four coal-fired steam turbines that operate as base load and one natural gas-fired combustion turbine.

We Energies’ principal business is providing electric and natural gas service to customers across Wisconsin and the Upper Peninsula of Michigan. They serve more than 1.1 million customers.

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