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Water cooled elements
Water cooled elements with protective cover are elaborated. Cover promotes decrease of panel oxidation, crack formation and heat loss.

EAF charge
A new technology base and approptiate equipment for carbon-thermal reduction of iron containing technogeny wastes is elaborated in order to utilize these wastes in capacity of part of the EAF charge.

EAF off gas suction elbow
EAF off gas suction elbow with a system of primary dust removal is elaborated. It provides a possibility of metal charge burning decrease due to partial return of heavy particles into the EAF.
Durability of water-cooled elements

Water-cooled elements (WCE) producers usually indicate life time of their units a few thousand heats. But in much cases these data isn’t grounded as necessary. Actually life time of the WCE depends on thermal and mechanical properties of panel material, thickness of the pipe wall, but mainly on exploitation conditions, and defines by experience in each case. Main reasons of WCR wear are the next.

1.The cracks caused by thermal stress. It is a consequence of temperature drop on section of the pipe, arising under action of heat flux, passing from working space of the furnace to water. The cyclicity of pressure connected with thermal cycles of the furnace operation, promotes development of the phenomenon of low- cycle to fatigue. In practice it is shown in formation of cross-section cracks of the WCE and accordingly leaks of water after 1-6 thousand heats. A heat flux passing to water - complex function of electrical arc furnace (EAF) technology parameters and WCE design. The most objective information on a passing heat flux can be received from thermal balance of the WCE on the basis of data about the flow rate and heating of water, its thermal capacity and the area of heat exchange surfaces.

2. An overheat of a working surface of a pipe above temperature 500-600 С (for carbon steel) at which arising in a wall cooled from within by water thermal stress reach a limit of fluidity of a material. Presence on a cooled surface of a pipe of a layer of salts of rigidity depositions, and is especially low-heat conductive products of corrosion, thickness of 0,5 mm and more at passage to water of a settlement het flux can cause heating of a surface of a pipe to temperature 800-1000 С and more (see figure). The thermal stress arising in a wall of a pipe, lead to formation of cross-section cracks. It is necessary to arrange for exception of corrosive attack of water, and the most effective kind corrosion inhibitor should be defined in each concrete case by practical consideration.

3. Burning by parasitic arcs of WCE pipes in process of the EAF operation. The given factor has casual character and is connected with infringements of rules of heat burdening and hit of not electro-conductive materials in a zone of arcs.

4. Oxidation of a working surface of a pipe by an atmosphere of the furnace. The given factor is constantly operating for all categories of WCE.

5. Abrasive deterioration of WCE working surface. It is characteristic for suction elbows, post combustion chambers and ducts where the high-speed stream dusty gas takes place.

рис. 1

Generalizing told, it is possible to result the parameters of stability proved by practice of steel-made WCE operation in the big metallurgy: 0,7- 4 thousand heats for suction elbow; 1-6 thousand heats for panels of the roof, walls (without taking into account burnings by arc) and EAF post combustion chambers; 8-13 thousand heats for frames of the casing and roofs of the EAF; more than 10 thousand heats for the dust removal chambers and ducts; 3-12 thousand heats for ladle-furnace roof and vacuum treatment unit screens; 0,5-2 thousand heats for the central part of the EAF roof. Concerning to stability of copper –made WCE, used in some designs of the wall panels working in contact with foaming slag (intensive technology in the EAF), and in the roofs of eccentricall bottom tapping device of the EAF, now are not present sufficient statistically a trustworthy information.

Our Company has original technique of experimental definition of the residual resource of WCE, operating in concrete conditions.
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