Four basic principles of green brick stacking in tunnel kiln

To ensure that the outer surface of each brick is in contact with air as much as possible, each brick can evenly exchange heat with the wind, so that the internal fuel can absorb as much oxygen as possible and burn fully, the following points must be achieved:

1. The green bricks shall neither be stacked too crowded to prevent the wind from moving, which will not only anoxic combustion, but also reduce the output; Nor could they be stacked too loose, which will blow away the heat, increase the coal consumption and reduce the output. Taking ordinary solid brick (overall dimension 240mm * 115mm * 53mm) as an example, it is generally considered that every 1m ³ of kiln room could be stacked 230 ~ 240 pcs bricks, which is called kiln density. When producing perforated bricks and hollow bricks, first convert the shape volume into the number of ordinary solid bricks according to the multiple of ordinary solid bricks (called ordinary brick coefficient), and then calculate the yard kiln density according to the kiln chamber space volume occupied by a kiln car. Since porous bricks and hollow bricks have holes and can also be ventilated, the kiln density calculated by standard conversion can be increased to 280 pieces / m ³~ 300 pieces / M ³， this is the reasonable kiln stack density.

2. After entering from the exit end of the tunnel kiln, the air moves along the longitudinal direction. In order to reserve enough air duct, the sum of the gap (air duct) between all bricks on the cross section of the billet stack and the total area of the gap between both sides of the billet stack and the kiln chamber shall not be less than 50% of the cross-sectional area of the kiln chamber. Ensure adequate ventilation area. Practice has proved that it is difficult for the wind to pass through the narrow joint with a width of less than 15mm. Therefore, the width of the reserved joint (air duct) between two adjacent bricks, especially the large surface of bricks, shall not be less than 40mm.

3. Because a wide side gap (50mm ~ 80mm) has to be reserved between the billet stack and the kiln wall, a wide air duct is formed. Too much air flows through, which contributes to the tendency of fire concentration in the middle. For tunnel kilns with a width of less than 3.3m, a middle air duct with a width about equal to the sum of the side gaps on both sides should be reserved in the middle of the billet stack, so that the same air volume flows through the middle. For wider kilns, more middle air ducts should be reserved, and the widest one in the middle (no more than 180mm) should be narrowed to both sides in turn. The total width of the air duct should be greater than the sum of the side gaps between both sides of the billet stack and the kiln wall. Due to the ventilation along the billet and the fire blocking of the horizontal billet, the lowest layer under the billet stack can only stack along the billet to increase the air volume at the bottom and prevent the primer from moving. This is the appropriate air volume distribution.

4. The wind can transfer heat only when it is in close contact with the brick surface. Therefore, when stacking the kiln, the outer surface of the brick must be exposed as much as possible, especially the large surface of the brick. It must not only be exposed, but also the gap between the two adjacent large surfaces shall not be less than 40mm to facilitate ventilation, which is the maximum heat transfer area.