Hoffman’s Kiln

This type of kiln is generally circular in shape but may also be rectangular and is covered with a roof. It is constructed above ground level. It has 8 to 24 chambers with a chimney at the center. Each chamber has a doorway which can be closed. Every chamber is also connected by means of the flue, which can be opened or closed, leading to the central chimney. At the top of each chamber, fire holes with covers are provided to feed fuel. Hoffman’s kiln is consists of 12 chambers.

It is a continuous kiln which works in all seasons. But it involves a very high initial cost so it is rarely used in India.

When chamber 1 is loaded with raw bricks, the burnt up bricks in chamber 2 are unloaded. The fresh air entering through the opened doors of chamber 1 and 2 gets heated by the bricks cooling in chamber 3 to 6 while the fuel in chamber 7 and 8 is burning. The hot gases coming from the burning chambers pass through the raw bricks loaded in chamber 9 to 12 and helps in drying them before burning. An iron gate is fixed at the end of chamber 12 and hot gases thus pass through the flue into the chimney. Usually, this type of kiln has a compartment with sizes of 12 m length, 5 m width and 2.5 m height, which can produce about 20000 bricks per day.

This type of kiln has a low fuel cost and having more percentage of good bricks. In the kiln, we get 80 to 90 % 1^st class bricks.