Firing furnace

A firing furnace comprising:

• a firing furnace main body having an internal passage from an inlet to an outlet;
• a first heating portion disposed in an upper portion of the internal passage;
• a second heating portion disposed in a central portion of the internal passage;
• a third heating portion disposed in a lower portion of the internal passage;
• a first transporting roller disposed between the first heating portion and the second heating portion;
• and
• a second transporting roller disposed between the second heating portion and the third heating portion,
• wherein a distance between the first heating portion and the second heating portion is greater than or equal to 1.2 times and less than or equal to 1.3 times a distance between the second heating portion and the third heating portion, and
• wherein in the firing furnace main body, a temperature rising zone, a temperature maintaining zone, and a cooling zone are sequentially arranged from the inlet to the outlet, a length of the cooling zone is longer than a length of the temperature rising zone, and a length of the temperature maintaining zone is longer than the length of the cooling zone,
• wherein the firing furnace main body includes a plurality of regions divided by partition walls, and
• wherein an average length of the regions included in the temperature maintaining zone is longer than an average length of the regions included in each of the temperature rising zone and the cooling zone,
• wherein the plurality of regions include a first region and a second region longer than the first region,
• wherein each of the temperature rising zone and the cooling zone includes a plurality of the first regions, and
• wherein the temperature maintaining zone includes the first region and the second region, the first region being disposed in a region adjacent to the temperature rising zone and the cooling zone.