Rectangular hearths

There is no limit to the possible configurations of electric furnaces. They exist as single-phase or polyphase, a-c or d-c, and one to six or more electrodes. The furnace cross sections can be round, heart-shaped, oval, rectangular, or variations of each. Some furnaces, especially those for silicon production, have a rotating hearth and shell. 

Example 5 Radiation in a Furnace Chamber A furnace chamber of rectangular paraUelepipedal form is heated hy the combustion of gas inside vertical radiant tubes hningthe sidewalls. The tubes are of 0.127-m (5-in) outside diameter on 0.305-m (12-in) centers. The stock forms a continuous plane on the hearth. Roof and end walls are refractory. Dimensions are shown in Fig. 5-20. The radiant tubes and stock are gray bodies having emissivities of 0.8 and 0.9 respectively. What is the net rate of heat transmission to the stock by radiation when the mean temperature of the tube surface is SIG C (1500 F) and that of the stock is 649 C (1200 F) ... 

Samples were obtained from pithouse floor assemblages, the perpendicular debris arc found next to the hearth of a Late Archaic pithouse, later expedient hearth features situated in secondary pithouse fill, secondary debris fill in pithouses, from along the edges of later rectangular structures, and from an exterior ritual area. Future studies will include a sample of archaeological ochre recovered from each of the burial contexts where it was encountered. 

The steelmaking components of an open hearth furnace consist of a rectangular heating zone with a floor containing a long shallow depression of 200-500 tonnes capacity into which the charge is placed (Fig. 14.3). Gas or... 

Open>hearth Furnace. A large rectangular furnace in which steel, covered with a layer of slag, is refined on a refractory hearth it is heated by gas or oil, and operates on the regenerative principle which was first applied to this type of furnace by Sir Wm. Siemens in 1867 (hence the earlier name siemens furnace). The type of refractory lining depends on the particular steelmaking process used see acid open-hearth FURNACE, basic OPEN-HEARTH FURNACE and all-basic FURNACE. The process is now obsolete. 

The furnace is rectangular in shape with a shallow hearth and arched roof. The floor and roof slope down to the firing end, and the opposite end contains a feeding port where the feed mix is continuously or intermittently pushed into the furnace. A natural gas or oil burner flame extends to the... 

Bricks are commonly produced by refractories and come in standard and nonstandard shapes. Nonstandard shapes are costlier. Standard shapes include rectangular prisms, tapered bricks, and tubular sleeves. Some refractory materials are supplied in granular form. These are called pea-sized refractories and are used in furnaces. To make the top layer of a furnace hearth, these pea-sized refractories are thrown onto the hearth while hot. They also are mixed with hot tar as a binder and are used as a lining for furnace hearths. Running repairs are made from castables. These are plastic preparations that can be made in any shape they are dried and fired in situ. 

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