Kilns

A kiln is a furnace oven or heated enclosure used for burning or firing brick or other clay material

Brick kilns can be classified into four categories, on the basis of how they are operated:

1. Intermittent or periodic kilns that consist of a single firing chamber. The intermittent kins are loaded with green bricks, which are fired and allowed to cool before unloading, in preparation of the next loading and firing. This type of kiln is capable of firing only one loading of bricks at a time

2. Semi-continuous kilns where two or more intermittent kilns are inter-connected by flues and dampers to allow the heat from the cooling bricks in one kiln to dry and pre-heat the bricks in another. The kilns are alternated being unloaded once the heat from the cooling bricks has been used to dry and pre-heat the bricks in the second kiln that is then fired up to top temperature

3. Continuous kilns where the firing zone moves through the bricks in the kiln without stopping. Green bricks are loaded in front on the firing zone and fired bricks removed behind it. These kilns run day and night, with the fire never going out, except for seasonal or maintenance stoppages.

4. Tunnel Kilns in which the bricks are placed on trollies and move through the hottest part of the kiln at a predetermined rate. This is a form of continuous kiln, but with stationary rather than moving firing zone

Kilns can be further subdivided into the three main classes, based on how they actually work:

A. Up-draught kilns where the heat travels naturally by convention, from the area of combustion up through the bricks

B. Down-draught kilns where the heat of combustion is drawn down through the bricks by the use of a chimney or forced draught system

C. Horizontal/Cross-draught kilns where the heat of combustion is drawn sideways through the bricks by the use of a chimney or forced draught system

from Gate Publication: The Basics of Brick Kiln Technology, Tim Jones, 1996

Click here to hear Alec Bank's recollections......

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