What is a zigzag kiln?
A zigzag kiln is a continuous kiln for firing bricks and other heavy clay products, in which the fire travels along a zigzag path from chamber to chamber. It belongs to the same family as the Hoffmann ring kiln: the fire burns continuously and moves through the kiln, while the bricks stay where they are.
How it works
In a ring kiln the firing tunnel runs in a closed ring or oval. In a zigzag kiln the kiln space is divided by cross walls that leave an opening alternately at one side and the other. As a result the fire travels back and forth through the kiln and, depending on the design, also up and down.
The principle is the same as in other continuous kilns:
- Preheating: hot flue gases pass through the chambers ahead of the fire, drying and warming the unfired bricks.
- Firing: fuel is added in the chambers where the fire is, and the bricks are fired.
- Cooling: cold air flows through the fired chambers behind the fire, cooling the bricks while being heated itself as combustion air.
- Drawing and setting: cooled chambers are emptied and refilled, ready for when the fire comes round again.
Because the heat is reused like this, continuous kilns are far more economical than older clamps and intermittent kilns, which had to be heated up and cooled down for every load.
Application
The zigzag kiln is regarded as a variant or improvement of the ring kiln. The back-and-forth path fits a long firing channel into a compact, rectangular plan. Today you mainly come across the term in descriptions of historic brickworks and listed kiln buildings.
Related terms
- Hoffmann kiln
- Lime kiln
- Brick clamp
- Green brick
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