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Interactions between electric arc furnace operations and environmental concerns


The use of oxygen and natural gas in the electric arc furnace can have positive as well as negative impacts on the cost of meltshop operations. The following general conclusions may be made: Oxy-fuel burners: centre dot Efficiencies of 40 to 60 percent may be achieved for good operations. For recommended burner rates, the increase in off-gas volume will be approximately 20 percent with a corresponding increase in off-gas heat load of approximately 33 percent. centre dot For operations in cold climates, the use of burners may lead to dew point problems in the baghouse. centre dot If sufficient excess capacity is not available in the direct evacuation system, the cost of modifications can be considerable (1 to 2 million dollars). Oxygen lancing: centre dot Typical energy input to the bath is 0.056 to 0.125 kwhr/scf oxygen with an average of 0.1 kwhr/scf. centre dot Optimum oxygen use is in the range of 1000 to 1250 scf/ton. centre dot Typically, 75 percent of the oxygen reacts with carbon to Produce CO. centre dot CO post-combustion can supply a significant amount of energy to the bath which, in turn, the heat load to the off-gas system. centre dot Lancing through the slag door can increase the fourth hole off-gas evacuation requirements by 100 to 200 percent and may result in higher NO_X production. centre dot High generation rates of CO may necessitate a post-combustion chamber in the direct evacuation system. centre dot If substantial amounts of CO are not captured by the direct evacuation system, ambient levels in the work environment may not be acceptable. centre dot Typically, up to 10 percent of the CO unburned in the furnace enters the secondary fume capture system during meltdown. centre dot For recommended lancing rates, the increase in off-gas volume will be approximately 35 percent, with a corresponding increase in off-gas heat load of approximately 80 percent. centre dot The effect of oxygen lancing on off-gas system requirements can be more severe than with oxy-fuel burners. If sufficient direct evacuation excess capacity is not available, the cost of system modifications can be higher (2 to 3 million dollars). Modern fume systems are now designed to minimize the formation of toxic gases and to insure that others are destroyed before exiting the system. Gas cleaning in a modern fume system entails considerably more than trapping and collecting particulates. With the tighter environmental restrictions expected in the future, it is expected that electric furnace operations will have to consider environmental concerns in conjunction with furnace operations. A variety of factors will affect the costs and processes necessary to maintain production and meet environmental restriction. Several new melting technologies have been developed with consideration given to environmental factors. Some have shown that a reduction in particulate emissions can be achieved. In terms of net emissions (ie, taking into account emissions in power generation as well as for steel-making), any technology that reduces electrical consumption will probably reduce net emissions. Thus, many of the new melting technologies are directed at both increased energy and environmental efficiency. The least expensive method of meeting emissions restrictions is to prevent these compounds from being present in the charge materials. Capture and treatment of pollutants is an expensive way of dealing with the problem. Tighter restrictions on feed materials will also affect productivity and operating costs. It will become necessary to weigh environmental considerations with operational concerns to establish an optimum that allows for low cost steel production while meeting emissions requirement. Environmental thinking must be integrated into operations to arrive at a low cost environmentally friendly steel production.......

【作者名称】: Jeremy A. T. Jones
【作者单位】: Senior process Engineer, Florida Steel Corp., Knoxville, Tenn.(At time of presentation)
【关 键 词】: Interactions between electric arc furnace operations and environmental concerns
【期刊名称】: Iron and Steel Engineer
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 108,663,362
【摘要长度】: 3,858
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