Hearth furnace

Small loads are commonly processed in a box furnace. The product is placed on the furnace hearth through a door. Box furnaces may be single-ended or double-ended. A single-ended box furnace is usually used in an air atmosphere appHcation where the product can be removed hot from the furnace for cooling. A double-ended box furnace is usually used in a controlled atmosphere appHcation. In this case a water cooler is attached to one end. The product can be placed on the hearth (in the heat chamber) through the front door, then after the product reaches temperature, it is manually transferred into the water cooler for cooling before it is manually removed out the exit door on the other end of the water cooler. 

The 2.5-fold increase in gas generation causes the mix burden to give away as hot gases and Hquid empt from the furnace hearth. 

The prime requirement of any carbonaceous material used in the blast furnace hearth wall or bottom is to contain Hquid iron and slag safely within the cmcible, throughout extended periods of continuous operation, often up to 15 years. 

For practical reasons, the blast furnace hearth is divided into two principal zones the bottom and the sidewalls. Each of these zones exhibits unique problems and wear mechanisms. The largest refractory mass is contained within the hearth bottom. The outside diameters of these bottoms can exceed 16 or 17 m and their depth is dependent on whether underhearth cooling is utilized. When cooling is not employed, this refractory depth usually is determined by mathematical models these predict a stabilization isotherm location which defines the limit of dissolution of the carbon by iron. Often, this depth exceeds 3 m of carbon. However, because the stabilization isotherm location is also a function of furnace diameter, often times thermal equiHbrium caimot be achieved without some form of underhearth cooling. 

The principles pertaining to carbon blast furnace hearths apply as well to submerged-arc furnace hearths. In some processes, such as in d-c arc furnaces, the electrical conductance of carbon is a most important factor. The long life of carbon linings in these appHcations is attributable to carbon s exceptional resistance to corrosive slags and metals at very high temperatures. 

Car-bottom furnaces differ from standard types in that the charge is placed upon movable cars for running into the furnace enclosure. The top oi the car is refractory-lined and forms the furnace hearth. The top only is exposed to heat, the lower metal structure being pro-tec ted by the hearth brick, sand, and water seals at the sides and ends and by the circulation of cooling air around the car structure below the hearth. For use where floor space is hmited elevator furnaces serve similar purposes. 

Feuer, n. fire furnace, hearth, forge light (as for a signal), beacon. 

Feuerungs-anlage, /. furnace, hearth, fireplace, -bedari, m. fuel requirement, -gewolbe, n. furnace arch, -material, n. fuel, -bl, n. fuel oil. -raum, m. Feuerraum. 

Gestell, n. frame, stand, support, base, rack, bed, mount (of a blast furnace) hearth, gestem, adv. yesterday, gestemt, a. starred. 

Blast furnace hearth design, 72 762-765 Blast furnace ironmaking, 74 498-509 Blast-furnace lead smelting, 14 734-736 Blast furnace material balance, 14 504 Blast furnace plant, 14 506 Blast furnace refractory, carbon as, 72 761-765... 

The coils are hung at the top from an articulated rod provided with a counterweight or a system of springs. They are fitted at the bottom with guides enabling them to move in slides prorided in the refractory of the furnace hearth. In this way, the supports are sot directly exposed to the radiant heat and the tubes assume a position in which the stress is a minimum and where sagging cannot cause substantial deformation. Expansion is allowed for, and thermal shocks are easier to withstand, thus lengthening coil life. 

Carbon refractories. Carbon blocks used in the construction of blast-furnace hearths are made from dense coke possibly mixed with anthracite. Suitable grain-size fractions (up to 5—15 mm) are mixed with tar to a plastic mass which is shaped at elevated temperature by pressing or ramming. The products are fired without air at about 1400 °C in saggers covered with fine-grained coke. The carbonized tar produces a firm bond between the grains. Granular mixes arc also used in certain applications. 

Units Rotary furnace Hearth type furnace Shaft fiimace Crucible furnace ... 

To prevent that problem, coauthor Shannon exhorts furnace owners to use more and shorter zones, and to locate control T-sensors low in the furnace sidewalls so that they can more promptly detect changes in load temperature (not furnace temperature), and thereby react more promptly. T-sensors must be installed no higher above the furnace hearth than the thickness of the load pieces. 

Roof heat losses should be expected to be below 600 Btu/fAr, sidewalls below 325 Btu/ft hr, and furnace hearth or bottom below 450 Btu/ft hr. 

This decomposition will, if necessary, take place relatively slowly at quite low temperatures, with the production of the beryllium fluoride in a finely divided form. The furnace used, however, is designed specifically to allow decomposition primarily above the melting-point (797°C) so that the coarse product resulting can be handled more easily and is less subject to hydrolysis. The furnace hearth is constructed of graphite, over which the decomposing ammonium fluorberyllate is fed continuously at a rate of about 35 Ib/hr. The fused beryllium fluoride is tapped off in 60 to 80 lb batches at a temperature of 900°C. The ammonium fluoride and decomposition products (ammonia and hydrofluoric acid) are led away from the furnace to condensers and scrubbers for recovery. 

Air Ramming. US term for the process of shaping a refractory brick or furnace hearth with a pneumatic rammer. 

All-basic Furnace. Abbreviation for All-Basic Open Hearth Steel Furnace. The whole of the superstructure of such a furnace-hearth, walls, roof, ports, ends, is built of basic refractories These furnaces were introduced in Europe in about 1935, the object being to make it possible to operate at a higher temperature than that possible with basic O.H. furnaces having a silica roof. Alligator Hide. (1) A vitreous-enamelware fault in the form of severe ORANGE PEEL (q.v ) and tearing (q.v.) eauses include too-rapid drying and too-heavy applieation of enamel. 

For the standard reverberatory furnace, a batch of galena was added to the furnace hearth and was roasted with hand-rabbling for about two hours, in which time part of the lead sulfide was directly oxidised to lead sulfate. The resulting mixture of lead sulfate and unreacted lead sulfide was thoroughly mixed and the temperature of the furnace was increased. This allowed the roast reaction , as given in Equation 2.1, to take place, with copious emission of sulfur dioxide ... 

Following this step, molten lead bullion was tapped from the base of the furnace hearth as a crude impure or hard lead. 

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