Because contemporary human living standards are closely related to the consumption of energy and water. The rapid increase in the global population makes it difficult to estimate the consumption of fresh water and energy. At present, our country has entered a period of severe water shortage. In order to ensure the sustainable development of the national economy, the issue of rational use of freshwater resources and effective conservation of freshwater resources is imminent. To protect the existing precious freshwater resources is to ensure the necessary living conditions for mankind. "When the well is dry, we know that water is expensive." Water conservation in power plants for large water users has become more and more urgent.

The air-cooling technology of power plants has become a hot topic in the construction of power plants. The cooling system of air-cooled units can save more than 97% of water, and the whole plant can save about 65% of water. Generally, 1m3/s of water can build a 1 million kilowatt wet-cooling unit, while the construction of a 1 million kilowatt air-cooled unit only needs 0.35m3/s of water. However, an air-cooled unit equipped with an air-cooled system requires a high one-time investment and a large standard coal consumption for power generation. The short period in summer also limits the output of the unit, which is not conducive to mass adoption.

Therefore, the use of air-cooled (dry-cooled) and water-cooled (wet-cooled) dry-wet combined cooling systems in power plants is a solution to the above two aspects and is a development trend of unit cooling systems. The combined dry-wet cooling system unit can not only exert the advantages of air-cooled units, but also maintain the advantages of wet-cooled units in saving investment, with high economic efficiency and unlimited output in summer. It is very suitable for water saving in variable working conditions, low load water saving at night and water saving in winter.

Dry and wet combined cooling systems can be divided into three categories: sub-built combined cooling systems, combined combined cooling systems and combined dry and wet heat dissipation surfaces compacted together combined cooling systems. Today, we mainly introduce the combined cooling system of dry and wet heat dissipation surfaces that are compacted together.

The dry and wet heat dissipation surfaces are compacted together with a joint cooling system. The dry and wet heat dissipation surfaces are compacted together and the combined cooling system is suitable for three operating modes: dry and wet combined operation or dry and wet separate operation. When the dry type is operated alone, according to the water level in the water distribution tank, many water spray devices of different lengths installed in the tower water distribution tank are controlled not to spray water to the cooling components within a certain range, and these cooling components operate in a dry manner; When the wet type is operated alone, the water spray device is controlled to operate in a certain mode; when the dry and wet modes are operated at the same time, the distribution of the dry and wet heat dissipation surfaces is realized by the regulating valve installed outside the tower. Only when the regulating valve is opened and the circulating water enters the water distribution tank equipped with a high-efficiency dewatering device, it can operate in wet mode. Otherwise, the regulating valve can be closed and it can only operate in wet and dry mode. The cooled circulating water is collected in a storage tank and then sent back to the condenser. The top of the tower is equipped with an exhaust-type axial flow cooling fan to cause air flow.