In front of the molecular sieve purifier, in order to reduce the temperature when the processed air enters the purifier, the whole low pressure oxygen generator is mostly equipped with nitrogen water precooling system, including air cooling tower and water cooling tower. In the air cooling tower, the air flows from the bottom to the top of the tower and enters into the molecular sieve purifier. The water sprays from the top of the tower to contact and mix with the air to cool the air, the air cooling tower is equipped with multiple penetrating sieve plates or stuffing to increase the gas-liquid contact area. In order to separate water, there is a water capture layer on the top of the tower. When the air velocity in the air cooling tower is too fast, there is too much water or too much water spraying, and the automatic adjustment of water level fails, water inflow accidents of the molecular sieve purifier will occur.
For example, a 30000 m 3/h oxygen generator in a factory, after the air compressor stops automatically, the pressure inside the air cooling tower drops, and when the air compressor starts again, water inflow accident of the molecular sieve purifier occurs. The reason is that the automatic water level regulating valve and the check valve of backwater system are out of order. When the air compressor stops automatically, the air inlet of the air cooling tower is filled with water at the check valve of the air compressor outlet, and the air compressor starts again. When the air enters from the lower part of the air cooling tower, press all the water into the air cooling tower, make the middle water level of the air cooling tower rise to the top and then enter the molecular sieve purifier along the exit pipe.
When the molecular sieve purifier enters water, the pressure of the molecular sieve fluctuates from high to low, the resistance of the adsorber rises, and the curve changes after heating and cold blowing. Among them, the most obvious one is the temperature drop after cold blowing, and the flat head peak appears. The longer the curve distance of Pingtou peak is, the more water is poured into the molecular sieve.
In order to prevent water inflow accident of molecular sieve purifier, attention should be paid to the operation:
① The air cooling tower should be operated according to the operating procedures. Air should be supplied first, and water should be supplied after the pressure rises and becomes stable;
② The gas volume cannot be increased or decreased suddenly;
③ Keep the water level of the air cooling tower;
④ The amount of water spraying should not be too large;
⑤ The water quality should meet the requirements, lower the inlet water temperature and reduce the scale.
After the water inflow accident occurs, the working condition of the air cooling tower should be handled first, the water supply of the water pump should be stopped, and the water level of the air cooling tower should be lowered and restored to the normal working condition. At the same time, reduce the production of the air separation plant to reduce the load of the molecular sieve, and activate the molecular sieve. When activating, pay attention to using large airflow to cool blow first. Heat again when the free water is blown clean. If the activation operation is not successful, only the molecular sieve can be replaced.
