Siemens VAI Metals Technologies received orders to inspect the existing hot-blast stoves at four production sites of U.S. steel producers and to propose repair and upgrading measures. The objective was to increase the hot-blast temperature and capacity as well as to improve the overall energy efficiency. The total order value of these projects is approx. 12 million U.S.-dollars.
Hot-blast stoves provide hot blast for the blast furnace process. Blast furnace top gas is used as the main energy source. Regular inspections and modernizations are important for an energy-efficient operation of hot-blast stoves.
For one U.S. producer, Siemens VAI was commissioned to carry out a process analysis for the hot-blast stove of one of the company's blast furnaces in preparation for a planned modernization in 2010. For the second blast furnace, which currently provides approximately 70 percent of production, Siemens VAI had already developed a new hot-blast stove design and delivered three stoves that have been in operation since the beginning of 2008.
At a second steel mill, Siemens VAI developed a new design for one of the stoves which will be installed in the course of 2009. A second stove also designed by Siemens VAI has been in use since the beginning of 2008. It is capable of providing hot blast temperatures of up to 1200 °C, which will be necessary after the planned blast furnace reline.
At a third site, Siemens VAI previously provided a stove design for one of the blast furnaces and supplied key components for a stove that was commissioned in late 2006. The current order includes the design of a second stove for the same blast furnace as well as the design of another stove for a second blast furnace. It is expected that these stoves will be rebuilt in 2010 and 2011.
An extensive reline of a blast furnace of a midwestern U.S. steel producer was performed in late 2008. Upon inspection by Siemens VAI, it was found that the stoves were in poor condition and could not sustain the operating parameters required for blast furnace operation. Siemens VAI prepared a repair plan that included defining refractory supply requirements and an accelerated installation schedule which would allow the stoves to be brought on line to support blast furnace production. This support service was critical to maintain the production capability of the blast furnace.