For the burner, if the combustion rate of the mixed gas is greater than the injection rate, tempering will occur.
It is difficult to defire, but the burner that is easy to temper will not have a wide combustion range. For example, if the flame hole is relatively large, it is easy to temper, so it is more difficult to handle. In order to prevent flashback, the following measures are usually taken:
① Make the flame hole small and deep, you can choose to increase the number of flame holes, and the combustion rate of the gas near the hole wall will be reduced due to the cooling effect of the flame hole wall. Multi-nozzle burners, etc., all belong to this method.
②If the heat received by the burner head is transferred to the inside of the burner, the unburned mixed gas will be preheated by this part of the heat. Therefore, ceramic materials with poor thermal conductivity are used to make the burner head, such as superheated burners and ceramic belt burners. Mouth and so on. In slotted radiant burners, the entire burner head, except the flame hole, is covered with a layer of ceramic fibers to increase the thermal insulation.
③ Cooling in the burner head at a distance away from the furnace body. Not only should the flame hole be small and deep, but also the burner head should be water-cooled or air-cooled, so that the cooling effect is greater. Usually the burner head is 10~25mm away from the furnace body. When using a premixed burner on the furnace.
④ For the burner with sleeve fire, because the sleeve fire is tempered first, reduce the flame hole of the sleeve fire (the slit is below 1mm) and cool it down to slightly reduce the speed of the sleeve fire, which is also good for preventing fire off.
⑤ When the primary air volume is reduced from 90% of the theoretical air volume to 70%, 50%, and 40%, the combustion rate will be reduced from 70cm/s to 50cm/s, 20cm/s, and 10cm/s, so it can be used to reduce primary air There are many examples in this regard by increasing the volume and increasing the amount of secondary air to prevent tempering. When using a premixed burner on the furnace, in principle, the primary air ratio is set to about 40%.
⑥If the injection speed is kept high, there will be no backfiring, but in this case, the adjustment range of the combustion amount will be narrowed. The internal pressure of the cup type radiant burner is usually above 25mmH2O.
⑦ The most fundamental measure Industrial burner to prevent tempering is to use a nozzle mixed burner (that is, burn while mixing in the burner part, gas and air).
The above are the countermeasures for the tempering of the burner during work. If you want to know more knowledge, please pay attention to Zhengzhou Bona Thermal Energy Co., Ltd.