News information
Fan and fan frequency conversion
08-19
The air volume and air pressure of the fan used in the brick and tile roasting kiln need oxygen, and the heat transfer needs air. Every firing in the tunnel kiln1kg of mud requires 5m3~6m3 of air and generates 6.08~7.08m3 of flue gas at the same time. A common solid brick raw material is about 2.8kg, and 18.24m3~21.24m3 of flue gas is generated for every common solid brick burned according to 3kg. The average is calculated as 20m 3/brick. If the kiln is designed to produce 5000 ordinary solid bricks per hour, the minimum air volume of the fan should be 5000 × 20=100000 m3/hour.
What is needed in the kiln is flowing wind, which is not enough because the wind has to be blown from the kiln end to the drying chamber (belt) and discharged into the atmosphere, so thisThe wind of 100000 m3 must also have "strength". The wind pressure unit is "Pa" (Pa). For the primary yard burning tunnel kiln or the secondary yard burning kiln with artificial drying chamber, there should be 1100 Pa ~ 1300 Pa. The wind of the fan depends on the continuously rotating wind wing (blade) to force the air to flow. The faster the wind wing rotates, the more air volume and the greater the wind pressure. Its characteristics are:
Speed and air volume is proportional. That is, if the fan speed is reduced by half, the air volume is also reduced by half;
The speed is proportional to the square of the wind pressure, that is, if the speed drops by half, the wind pressure is only the square of 1/2, that is, 1/4;
The speed and shaft power is proportional to the cube, that is, if the speed is reduced by half, the shaft power only needs 1/8 of the original quota.
Therefore, when reducing the frequency of the fan, we must not only consider the air volume and electricity saving, but also take into account the wind pressure to avoid wind."It doesn't blow". The method is that every time the frequency conversion is lowered, a newspaper must be sucked on the brick pile of the kiln car about to come out of the kiln, indicating that the wind pressure is in place, the greater the suction, the greater the wind pressure. If the newspaper cannot be sucked, it means that the wind pressure is not enough, and the frequency conversion must be increased immediately and the air damper or damper must be used to adjust the air volume.
When using the Harbin air brake, whether it is a step gate or a bridge gate, the height of the first gate (the gate closest to the roasting) should be 1/5 the height of the remote gate (the gate closest to the kiln gate). 1/5 the bridge gate is the highest gate, the transportation gate should be the highest 2/5, and the principle of lifting first and then falling, and lifting slowly and falling should be adhered.
When shielding the brick stack at the end of the kiln to control the air and limit the oxygen, it should be noted that if the baking zone is at high temperature in the upper part, the upper part of the brick stack should be shielded. If the baking zone is at high temperature in the lower part, the lower part of the brick stack should be shielded.
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