What is the principle of backflow incense?

Like our usual cooking smoke, cigarettes, and incense sticks, the smoke after burning is upward. As long as it is the dust of the fireworks produced by the combustion, the mass is greater than the specific gravity of the air, but there will be hot air during the combustion process. As these dusts rise, the smoke of the incense flow is so special that it needs to be realized with the help of a backflow furnace. The backflow incense burners are all dedicated incense towers with a small hole in the inside of the incense tower. There is also a small hole on the backflow furnace, just in time. It is aimed at the small holes on the incense tower, which is conducive to the outflow of smoke and isolates the hot air from the outside air. The smoke will be locked in the small holes in the incense tower. After cooling, the specific gravity of the smoke at this time will be reduced. Heavier than air, the smoke will flow down like running water. This is how backflow incense works.