Cupola furnace

Tliis ignition source includes sparks released from foundry cupolas, furnaces, and incinerators. 

Induction furnaces offer certain advantages over electric arc or cupola furnaces. An induction furnace emits 75 percent less dust and fumes, due to the less turbulent nature of the heating employed inside the furnace. When coupled with the use of relatively clean scrap material, the need for emission control equipment may be avoided. For more information on induction furnaces, refer to USEPA (1985), and Danielson (1973). 

Many different chemical treatment systems have been developed to reduce the leachability of lead and cadmium compounds in flue dust. These systems usually rely on stabilization/solidification, adsorption, chemical reduction, or pH control. Chemical reduction employing the use of metallic iron has been successful in reducing the leachability of lead to below EP-Toxicity levels. Adding a 5 percent by weight dose of iron filings to cupola furnace emissions control sludge, for instance, reduced lead leaching from 28.6 mg/1 to less than 0.1 mg/1 (Stephens 1984). 

The types of coke and by products (such as gas tar) differ with the type of carboni-azcion process. The coke obtd from high temp process is the least reactive and has the greatest structural strength. For these reasons, it is suitable for use as blast-furnace and cupola -furnace fuels. The coke obtd from low temp process contains considerable amt of liquid ingredients, but produces little smoke on burning. It is considered very suitable as a domestic fuel, because it is easy to ignite and, when... 

Cupola Furnace Explosion. A violent expln occurred in one of the cupola furnaces of Germany-, shortly after starting the blast. 

Water-cooled cupola furnaces several meters high and with shafts up to 1 m wide are used for the manufacture of rock and slag fibers. The raw materials are added alternately with coke. Metallic iron is formed from the iron-containing raw material and has to be regularly drawn off. 

Morawe, F., Enriching the blast of the cupola furnace with oxygen, Giesserie, 74, 132-155, 1930. 

Raw materials, including fluxes in lump and powder form foundry cokes for cupola furnaces deoxidants and refractories are normally stored under cover. Following delivery, handling is kept to a minimum. Powdered materials may be stored in sealed silos and conveyed pneumatically or kept and handled in sealed bags, as displayed in Figure 2.8. 

Figure 2.9 Schematic outline and miniature model of a (cold blast) cupola furnace [44, ETSU, 1993], [237, HUT, 2003]...

In order to optimise the efficiency of the cupola furnace, the combustion air may be preheated. 

Type Electric Arc Furnace Induction F. Induction F. Cupola Furnace Rotary f. 

Table 3.6 Unbumed top gas composition for cupola furnace [32, CAEF, 1997]...

The cupola furnace has the specific feature that the lining material (quartz-clay mixture) of the furnace at the melting zone only lasts for one melting campaign. The main part of the refractory is converted into slag. The amount to be taken out and disposed of as waste is much smaller than the applied amount. 

The melting of iron and steel in induction furnaces results in low emissions compared to the cupola furnace. Emissions due to the combustion of fossil fuel are especially prevented. An exhaust capture efficiency of up to 95 % is possible using special capture systems, such as side-draughts, movable hoods and partial covering of the furnace. Filtration of the off-gases is mainly performed using dry systems. Dust emission levels below 5 mg/Nm can be obtained [225, TWG, 2003]. Typical emission data are given in Table 3.14. 

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