We have all seen the big chimneys in power plants. Why should they be designed so big?

What exactly is the "big chimney" of a power plant for? You may not believe it when you say it

Students who live in the suburbs must have seen big chimneys in their lives. They keep emitting black smoke all day, which makes the air quality worse and worse. There are such big chimneys around the power plant. What are they for? You may not even believe the answer.

First of all, some friends may hear the name of the chimney and take it for granted that it must be used to emit exhaust gas. Actually, it's not like this. Its professional name is cooling tower. As we all know, most power plants in China use thermal power to generate electricity, and fire will inevitably produce high temperature during combustion. If you don't use this cooling tower, you need a lot of cold water to control its temperature within a reasonable range, and the cost will go up at once. And now that water resources are so precious, it's really a waste to do such a thing.

As for why smoke comes out, it involves some junior high school physics common sense. As we all know, water exists in three ways: gas, liquid and solid. The water in the cooling tower is liquid, which will act as steam at high temperature. In our opinion, it is the big chimney that is exhausting.

In fact, this big chimney has another function, that is, it can recycle water resources. When the water vapor goes outside, it will liquefy into liquid water, which can be put into use again because of the different temperature and pressure inside.

In fact, its structure is far from being as simple as what we can see with the naked eye. There is also a reservoir outside it, and the liquefied water vapor will fall into this reservoir and be put into use after the water has accumulated to a certain extent. This design can reduce the cost and reduce the dependence on manpower.

The design of this chimney is also very interesting. The top is small, but the bottom is thick. In fact, this also takes into account the practicality, because the chimneys of power plants are generally relatively high, and 50 to 60 meters is the normal state. The chimney of this shape is more stable while saving cost, and there is no need to worry about collapse and other problems.

This design can also make the air flow faster. If the top and bottom are the same thickness, the pressure difference may not be so obvious, and the speed of gas flow will slow down, so its effect will be affected to some extent.

To sum up, the building next to the power plant, which is thin on the top and thick on the bottom, is not used to discharge exhaust gas, but the building with the same thickness at the bottom and top is used to discharge exhaust gas. Its main goal is to cool down.