Continuous production of Hoffman kiln
Continuous production of Hoffman kiln
The Hoffmann kiln is a so-called “continuous kiln” – it burns 24 hours a day, 7 days a week, 365 days a
year (except when it goes down for maintenance). Before its invention, bricks and tiles were fired in
so-called “periodic kilns”. This method was very time-consuming because it is essential to ensure that
ceramic materials are not heated up and cooled down too fast. This meant that the fire had to be increased
very slowly and carefully, and that the baked bricks had to remain in the oven several days after the
fire was extinguished. During this whole period, the periodic oven could not be used to bake a new stack
of bricks. Moreover, the structure itself had to be heated up every time, and during the firing process
most heat was lost through the chimney or the roof, wasting large amounts of fuel.
The original Hoffmann kiln was circular in plan with a large chimney placed at the centre (illustration
above), but this shape was abandoned quickly for an elliptical outline, and ultimately a rectangular
shape with two parallel tunnels built side by side, connected by curved tunnels at either end
(illustration further below). The chimney could be in the middle, or next to the building. A rectangular
kiln saved space, was easier to operate and allowed for a more homogeneous air circulation.