The place where fuel is burned in a kiln. Older kilns did not have a special structure; they were simply filled with goods and fired with wood at the entrance. As kilns advanced, various innovations were made to the kiln mouth. However, as fuels have changed from coal to fuel oil and gas, the combustion system has become more complex, but the fire opening has also become simpler. There are various types of fire exits, including those without a rostrum, those with a horizontal rostrum, those with a sloping rostrum, those with a staircase of rostrums, and those with a combination of the above. The number of fire openings and their sizes must be considered according to the size of the kiln, the shape of the kiln, the structure of the opening, the firing temperature, the firing time, the nature of the fuel, the strength of the ventilation, etc.
