Water cooling tower is a hybrid heat exchanger. The purpose is to lower the temperature of cooling water in the cooling tower after cooling the air, so that the air cooling tower can be recycled. Different types strive to enhance heat transfer, improve cooling effect, and at the same time, flow resistance should be as small as possible, so that water is not easy to scale.
The structure of water cooling tower selected by large air separation plant in our country roughly has the following types:
1) stuffing tower. In the early stage, it was a Laci ring with porcelain. Its heat transfer effect was good and the resistance was not big. However, when it is used in the process of self-clearing low pressure, because the switching system is switched once every few minutes, when the switching is emptied, the impact of airflow on the porcelain ring is relatively large, which is easy to cause the damage of the porcelain ring and increase the resistance. Some are also changed into plastic rings to increase the strength. Currently at 6000 ~ 40000m3A new type of stuffing tower is used on the air separation plant of/h, which adopts Alpha ball ring or common ring and ladder ring. It has the advantages of large flux, small resistance, good heat transfer effect and good strength. The temperature difference of heat transfer at the hot end is about 0.5 ℃, and the negative temperature difference of effluent (the temperature of water is lower than that of nitrogen) can reach 4 ~ 9 ℃, depending on the gas-liquid ratio.
2) swirling plate. It is composed of several metal structure swirling Tower plates. This kind of structural resistance is very small and will not be damaged. It has been used as an improved type for quite a long time. But the heat transfer effect than packed tower.
3) sieve tower. The tower plate adopts drench Tower plate with larger aperture and hole spacing. Both nitrogen and water pass through the sieve hole. Since the water cooling tower does not work continuously and stably, the cooling effect is not ideal enough, so it is no longer used now.
