Packed blast furnace

Noncatalytic packed bed reactors have been discussed separately in other sections of this article. They include blast furnaces, convertors, roasting furnaces, rotary kilns, and gasifiers. 

C = coefficient of heat conductivity measured in heat units per unit time per unit of packing volume per deg temperature difference usual units are cal per sec per deg C per cc m = a constant for limestone packings, m = 0.0073 for iron ore, 0.0105 anthracite and other coals, 0.0050 blast-furnace charge, 0.0072. The values are in metric units. q = volume of gas flow per unit-time per square unit of cross-sectional packing area, expressed as liters per sec per sq cm T = temperature, deg abs, C = fractional voids (dimensionless) d = diameter of particles, cm... 

Furnas also derived equations for conditions simulating blast-furnace practice. These equations permit the calculation of the steady-state temperature at any point within a column through which the packing and a hot gas move counter to each other. Furnas assumed that the solids entering the column were at zero deg C. His equations giving the temperature at any point in the column -distant from the bottom are ... 

Carbon Refractories. These refractories, consisting almost entirely of carbon, are made from a mixture of graded coke, or anthracite, pitch and tar the shaped blocks are fired (packed in coke). The fired product has an apparent porosity of 20-25% crushing strength 50-70 MNm-2 R.u.L. (350 kPa), 1700°C thermal expansion (0-1000 C), 0.65%. The principal use is in the lining of blast furnaces, particularly in the hearth and bosh (cf. plumbago). 

Physically, the blast furnace is a packed bed into which a mixture of coke and specially prepared ore (sinter or pellets) is charged at the top and a hot air blast is blown through tuyeres located at the bottom. The descending iron oxide is made to react with the reducing gases (principally CO) produced by the reaction between the hot blast and the coke, ultimately yielding blast furnace hot metal that is tapped from the lower end of the furnace. 

The next development was the application of hand, or foot, operated bellows to provide an air blast to the hearth, which enabled the smelting site to be more conveniently located near ore supplies. The furnace was constructed as a short, square shaft with a bottom opening for the bellows and to allow metal and slag to run out. The shaft was packed with charcoal and ore. An example of this type of furnace is the Catalan Eorge, introduced in Spain about 700 AD. 

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