In the plate type 6000m3 / h air separation plant, the air flow is only 33000m3 / h, while the annular flow is 5200m3 / h, resulting in air liquefaction at the cold end of the switching heat exchanger. When the circulating flow is reduced to 3400m3 / h, the gas distribution of each unit is reasonable, and the liquefaction phenomenon disappears. In addition, it is also related to the performance of liquid air subcooler, liquid nitrogen subcooler and liquefier. The main ignition sources of air separation plant manufacturers are as follows: 1) the solid particles of explosive impurities rub against each other or against the vessel wall; 2) Electrostatic discharge. When there are a small amount of ice particles and solid carbon dioxide in liquid oxygen, static charge will be generated. When the carbon dioxide content is 2 × 10-4～3 × 10-4, the electrostatic potential can reach 3000V; 3) Gas wave shock.
When the oxygen yield decreases, the oxygen purity will increase, and the argon rich region will move up, that is, the argon content in the argon rich region of the distillation section will increase, while the argon content in the argon rich region of the stripping section will decrease. This is because on the same tray, the total content of oxygen, argon and nitrogen in the gas phase should be 100%, and the total content of oxygen, argon and nitrogen in the liquid phase should also be 100%. In case of failure, the manufacturer of air separation unit shall deal with it in time; Pay close attention to the operation of the refrigerator. In case of short-term failure, which causes the air outlet temperature to rise, the switching cycle of the adsorber should be shortened in time, and the failure should be eliminated in time; When starting the air compressor, the pressure rise should be carried out slowly to prevent the air speed from being too high.
With the decrease of the argon fraction extraction, the reflux ratio of the upper tower decreases correspondingly, and the oxygen purity increases, so the nitrogen content in the argon fraction decreases correspondingly. As a result, the temperature difference of the condensing evaporator will expand, the fraction extraction will automatically increase, and the nitrogen content in the argon fraction will increase. This repeated change makes the crude argon column unable to work normally. The most likely leakage place of the switching heat exchanger is the weld, especially the joint between the head and the 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.
Temperature method. When the leakage occurs between the air channel and the polluted nitrogen channel, the temperature in the middle will change obviously, and the leakage unit can be determined from the temperature change. Moreover, the amount of air intake will also increase. Repair welding shall be carried out after identifying the leakage position. If it is an individual channel leakage, the channel can be sealed. When serious leakage cannot be solved, the heat exchanger unit shall be replaced. The range of temperature change of air separation plant manufacturers is proportional to the temperature difference, so it also reflects the size of the temperature difference. When examining the temperature difference between the hot end and the cold end of a cold accumulator, it is necessary to measure it strictly, instead of using the temperature amplitude to replace the temperature difference. The temperature of the middle part or the middle part of the pump is also changing in a switching cycle, which is usually measured before switching.
Cold running loss Q3 (or Q3). The interior of the air separation unit is in a low temperature state. Although the cold insulation box is filled with insulation material, because the external environment temperature is higher than the internal temperature, more or less heat will be transferred to the interior. The heat from the outside is actually that the same amount of cold energy of the low temperature gas is not fully utilized. Because of the heat from outside, the temperature of low temperature gas will rise. If we want to keep the internal temperature stable, we must try to bring the incoming heat out of the device, that is, we need to consume the same amount of cold energy, which is called "running cold loss". The air separation plant manufacturer shall close the oxygen regulating butterfly valve and fully open the dirty nitrogen and pure nitrogen regulating butterfly valve. Turn off steam source of steam heater. Cut off the power switch of electrical equipment and make it in the start position. After finding out the cause of the power failure and eliminating the fault, make preparations for the start-up.
