Clay brick making machine-Brick machine-Baoshen brick making machine

Comparison between Hoffman kiln and tunnel kiln.

In a Hofmann kiln the bricks stay where they are and the fire moves around, but in a tunnel kiln the fire
remains stationary while the bricks move slowly through the tunnel. The fire is situated in the centre
and the bricks slowly proceed through the tunnel on a train or a conveyor belt, so that bricks which are
in the beginning of the tunnel are slowly being preheated by the fire further on, and bricks which have
passed the fire are allowed to cool down gradually.

Tunnel kilns are much more expensive to build than Hofman kilns, but they save on labour costs because
they can be highly automated – today they operate without a human in sight.

Still, in spite of all that high-tech, they are not more energy-efficient than Hoffman kilns – both
processes require around 2,000 kilojoules per kilogram of brick.

If compared to some improved versions of Hoffman kilns, a tunnel kiln is even less efficient. Moreover,
in modern brick production facilities all too often energy efficiency is sacrificed for speed and the
drying and cooling processes are fastened by means of extra energy inputs (see the specifications of a
modern tunnel kiln).

The reason for the existence of a tunnel kiln is that the production process is further accelerated,
resulting in a much larger output of bricks. This might as well be the most devastating aspect of modern
brick production, because there seems to be a correlation between the speed of production and the ease
with which we demolish buildings.