Why do factories build tall chimneys?

The main function of the chimney is to pull out fire and smoke, exhaust smoke, and improve combustion conditions.

When the temperature inside the chimney is higher than the temperature outside the chimney, the hot air inside the chimney will naturally rise along these chimneys due to its low density. The cold air outside the chimney will be supplemented by infiltration from the lower floors due to its high density, which forms a chimney. effect. The chimney effect is the result of the simultaneous action of the heat pressure caused by the temperature difference between the inside and outside of the chimney and the outdoor wind pressure. The former is usually dominant, while the heat pressure value is determined by the air density difference caused by the temperature difference inside and outside the chimney and the height difference of the air inlet and exhaust vents. Proportional. This shows that the higher the temperature inside the chimney is than the outdoor temperature, the higher the chimney, and the more obvious the chimney effect. Some data show that the vertical diffusion speed of smoke in the vertical tube well is 3-4m/s, which means the height is 50m. It only takes about 15 seconds for the fireworks to fly directly from the bottom to the top of the chimney.

In addition, strong winds at high altitudes facilitate the spread of smoke and dust, which is beneficial to reducing local pollution. But that's not the main thing. It is also not good for controlling pollution and cannot play a fundamental role.