reverberatory furnace - Applications and comparison with blast furnace, History

A furnace in which the contents are not heated directly by the burning fuel, but by hot flames diverted by the roof of the furnace so as to play down on the material to be heated. Although mainly known in steel making, it is also used in other processes such as glass making or ceramics.

A reverbatory furnace is a metallurgical or process furnace which characteristically isolates the material being processed from contact with the fuel, but not from contact with the combustion gases. The reverberatory furnace can be contrasted on the one hand with the blast furnace, in which fuel and material are mixed in a single chamber, and, on the other hand, with crucible, muffling, or retort furnaces, in which the subject material is isolated from the fuel and all of the products of combustion including gases and flying ash. It has been stated in some contexts that the reverberatory furnace also typically separates the material from the hot gases, but this does not seem to be the case in general.

Applications and comparison with blast furnace

The applications of these devices fall into two general categories, metallurgical melting furnaces, and lower temperature processing furnaces typically used for metallic ores and other minerals.

A reverberatory furnace is at a disadvantage from the standpoint of efficiency compared to a blast furnace due to the spatial separation of the burning fuel and the subject material, and it is necessary to effectively utilize both reflected radiant heat and direct contact with the exhaust gases (convection) to maximize heat transfer.

Reverberatory furnaces (here usually called air furnaces) were formerly also used for melting brass (i.e.

History

The first reverberatory furnaces were perhaps in the medieval period, and were used for melting bronze for casting bells. Sir Clement Clerke and his son Talbot built cupolas or reverberatory furnaces in the Avon Gorge below Bristol in about 1678. In the following decades, reverberatory furnaces were widely adopted for smelting these metals and also tin.

In the 1690s, they (or associates) applied the reverberatory furnace (in this case known as an air furnace) to melting pig iron for foundry purposes. This was used at Coalbrookdale and various other places, but became obsolete at the end of the 18th century with the introduction of the foundry cupola, which was a kind of small blast furnace, and a quite different species from the reverberatory furnace.

The puddling furnace, introduced by Henry Cort in the 1780s to replace the older finery process, was also a variety of reverberatory furnace.