DEAR Air separation equipment.If the molecular sieve bed is uneven and the thickness of the bed through which the airflow passes is different, the maximum temperature will not be reached at the same time at the outlet. Several peaks may appear after mixing, or the whole peak may be relatively flat, the peak temperature will decrease, and the shape of the cold blowing curve will also become "short and fat". In this case, heating and cold blowing to the specified temperature often takes longer.Expander, freezer, air precooling system and argon purification system shall be shut down by interlocking. If there is no shutdown, it should be stopped manually; stop the delivery of oxygen, nitrogen and other products, stop the removal of liquid oxygen, liquid nitrogen and liquid argon; close the water valve connecting the air precooling system with the outside. The rest are operated according to the requirements of normal shutdown. After the above operation, find out the cause of the fault and prepare for restart.
Low temperature valve is often flexible in normal temperature, low temperature is very tight, or even open. The main reasons for the valve stuck at low temperature are as follows: during installation, the pre stress is produced due to the unreasonable configuration of the valve and pipeline; or the valve position is changed due to the poor cold compensation capacity of the pipeline at low temperature; or the valve is deformed due to the lack of support at low temperature; or the valve is improperly fixed and the cold box is deformed at low temperature, which affects the concentricity of the valve stem and valve body.In the installation, there should be a firm support at the valve to prevent the valve from bending the valve stem with the displacement of the pipeline. The valve and the cold box can be fixed by elastic connection to prevent the valve rod from being deformed and not concentric with the valve body; during the naked cold period, the valve installation should be checked and adjusted in the cold state.
If the nitrogen content of argon fraction is high, the temperature difference in the condenser of crude argon column will be reduced, even to zero. In this way, the crude argon condenses less or does not condense, which makes the crude nitrogen tower unable to work normally. This will reduce the extraction of argon fraction and the velocity of updraft, resulting in liquid leakage from the tray.DEAR Air separation equipment.The cold insulation box is filled with insulation materials with poor thermal conductivity, such as pearlite and slag cotton, so as to reduce the heat transfer from the outside. In addition to the performance of insulation material, the thickness of filling layer and the insulation measures of support, the cold insulation condition is also related to the filling condition.In the process of putting the crude argon column into operation, firstly, the argon fraction is extracted to pre cool the crude argon column, and then the liquid air is gradually sent to the crude argon condenser. With the cooling of the crude argon column, the distillation condition of the crude argon column is gradually established. The sign is that the resistance of crude argon tower, the purity of crude argon and the extraction amount of argon fraction continue to increase until the normal index is reached. At the beginning, the main cooling liquid level may drop slightly, and with the establishment of crude argon column distillation, the main cooling liquid level will recover.
DEAR Air separation equipment.Water cooling tower is a kind of hybrid heat exchanger. The cooling water with higher temperature (about 35 ℃) from the air cooling tower flows downward from the top spray, and the sewage nitrogen with lower temperature (about 27 ℃) from the switching heat exchanger flows from bottom to top. The two are in direct contact, which is a complex heat transfer process with heat and mass transfer.DEAR Air separation equipment.Before filling molecular sieve, check the sieve bed to avoid molecular sieve leakage, otherwise it should be treated. There should be no oil and other sundries in the tank; the filling personnel should not wear work shoes with nails to avoid stepping on the sieve bed; they should wear clean work clothes without oil. Several standard height marks should be made in the middle part. First check the ring chamber, fill the aluminum glue to reach the standard height, and then fill the molecular sieve.Cold and hot fluid flow through different channels at the same time, and transfer heat through the baffle and fin, so it is called plate fin heat exchanger, also known as compact heat exchanger. It is the most widely used heat exchanger in today's air separation unit (except for high pressure).
