The liquid oxygen surface of condensing evaporator of air separation plant manufacturer is required to be kept at a certain height (data provided by the design and manufacture unit), so as to strengthen heat exchange and ensure operation safety. The heat transfer process of condensing evaporator is the process of condensing gas nitrogen to release latent heat and transfer heat to liquid oxygen to vaporize it into gas oxygen. The moisture content of the air into the tower of the air separation plant manufacturer is determined by the distillation system according to the heat balance of the tower. Because the heat transfer temperature difference of the main heat exchanger is larger than that of the switching heat exchanger, the heat transfer area needed to transfer the same heat can be reduced, so the length of the non switching plate fin heat exchanger is generally shorter than that of the switching heat exchanger. The most common leakage place of switching heat exchanger of air separation plant manufacturer is weld, especially the joint between head and pipe. The causes of leakage are mostly manufacturing and installation quality problems, and also related to maintenance. The working condition of the switching heat exchanger is poor. It is not only impacted by the alternating air flow, but also the air temperature changes greatly. In the long-term operation, the weak part is easy to leak.
Using low temperature liquid to cool other normal temperature equipment, the irreversible loss is large, and the use of cooling capacity is not reasonable. Moreover, the equipment will produce large thermal stress, which has an impact on the service life. Compared with the stage cooling method, the operation time of the expander is shorter under the condition of higher inlet temperature, so it can not give full play to the characteristics of the larger refrigeration capacity of the turbo expander under high temperature, and the start-up time is relatively longer. For a certain amount of gas, in a certain volume, its pressure (absolute pressure) is directly proportional to the temperature (thermodynamic temperature K). At the end of oxygenation, the temperature T1 of the cylinder is higher, and the measured pressure P1 is also the pressure at a higher temperature. After a few hours, when the temperature drops to T2, the pressure must also drop. This is not necessarily due to the leakage of the air valve.
According to the statistics of the air separation plant manufacturer, besides the condensing evaporator, there have been explosions in other parts. Including: lower part of liquid air inlet of lower tower; Liquid air adsorber; Tray at liquid air inlet of upper tower; Liquid oxygen discharge pipe; Liquid oxygen pump; Oxygen channel at cold end of switching heat exchanger; Acetylene separator after auxiliary condensing evaporator, etc. Water cooling tower is a kind of hybrid heat exchanger. The purpose is to lower the temperature of the cooling water in the cooling tower after cooling the air, so that it can be recycled in the air cooling tower. Different types are to strive to enhance heat transfer, improve cooling effect, while the flow resistance should be as small as possible, so that water is not easy to scale. In order to make the main cooling precooling complete, the gas in the main cooling channel must be unblocked in the cooling stage. Therefore, it is necessary to open the pure liquid nitrogen control valve, close the liquid nitrogen return valve and the sewage liquid nitrogen control valve, and use the cold air from the lower tower to cool through the main cooling nitrogen channel.
