Chimney construction precautions

"The higher the chimney, the better the smoke ability", "the higher the air pressure is smaller" these two sentences are correct, but the higher the chimney smoke ability is not because the higher the air pressure is smaller, if it is really caused by this reason, let alone the air in the chimney will flow upward, that is, the air on the ground will all run up.

Any object created in the atmosphere (including the air itself) is subject to buoyancy from the air, but why can the air remain balanced (regardless of the phenomenon of blowing) and not rise? That is because the air is not only affected by the rising float, but also by its own gravity, usually the upward buoyancy of the air and its own downward gravity is equal, so it maintains balance.

But the smoke discharged from the chimney is hot air at a very high temperature, and the higher the temperature, the more it rises, and the gravity per unit volume becomes smaller, because the buoyancy does not change, and the gravity of the hot air becomes smaller, so the smoke floats up, rushes up, and when the temperature becomes cold for a while, the smoke spreads horizontally. If you stand on a mountain in the countryside when there is no wind (preferably in the early morning and evening) and watch the fireworks of farmers in the valley, you can see this phenomenon, which is very spectacular.

Why should the chimney be high? Because the higher the chimney, the more hot air in the chimney, the greater the total buoyancy force it is subjected to, the greater the pressure generated by the buoyancy force, and the stronger the smoke discharge capacity. Is it OK to make the chimney bigger instead of taller? Of course not, if you only make the chimney big and not high, the smoke by the buoyancy will also become larger, and proportional to the cross-sectional area, but the pressure = pressure/force area, pressure, area are proportional to the increase, the pressure actually does not change, the suction of the lower part of the chimney will not become larger, this reason is related to the lift of the pump only with the vertical height of the water pipe, It has nothing to do with the horizontal distance.