1.1 poor quality of molecular sieve
Molecular sieve is a kind of adsorbent for separating nitrogen and adsorbing oxygen. Its quality directly affects the performance and purity of nitrogen generator. The anti dust, moisture-proof ability, strength and adsorption of high-quality molecular sieves are better than those of general molecular sieves, while the service life of low-quality molecular sieves is shorter, which aggravates the pulverization during operation.
1.2 molecular sieve filling is not solid
There is no professional filling vibration equipment when filling molecular sieve in nitrogen generator, which leads to low filling density of molecular sieve in nitrogen generator. When the nitrogen generator is running, the compressed air flow rises through the bottom of the tank, the oxygen is absorbed by the molecular sieve, and then the nitrogen is transported to the downstream pipeline. Due to the frequent impact of air flow, the internal molecular sieve wear intensifies, and the material level of molecular sieve gradually decreases. When it falls to the lower limit of the top cylinder, the cylinder will no longer press the molecular sieve and limit the operation, thus accelerating the pulverization of molecular sieve, resulting in the powder passing through the filter screen and emptying with oxygen enrichment.
1.3 air source pressure
The purified compressed air enters into the bottom of the nitrogen generator tower, and the pressure of the gas source affects the working condition of the nitrogen generator. Due to the high frequency of pressurization and decompression of PSA nitrogen production equipment, the impact of pressurized gas on molecular sieve is very serious, resulting in the wear of carbon molecular sieve. Therefore, the pressure and flow rate of gas source should be strictly controlled. If the air source pressure is too high, the impact of the air source on the molecular sieve is large at the moment when the pneumatic valve is opened, which increases the friction between the molecular sieves. When the molecular sieve is fully adsorbed, the static friction is relatively large at the moment when the pneumatic valve is closed. If the gas source pressure is too low, the time for the molecular sieve to absorb oxygen to reach saturation is longer. In other words, the working time for the nitrogen generator to output qualified nitrogen is longer, and the friction time between molecular sieves is longer, which accelerates the pulverization of molecular sieves.
1.4 the pneumatic valve is not tight
The pipeline of nitrogen generator is equipped with pneumatic quick opening butterfly valve group, pressure equalizing valve group, exhaust valve group and vent valve group. If any valve group is not closed tightly, air leakage may produce air flow in another nitrogen generator which is not working temporarily. The surge of air flow will also increase the static friction between molecular sieves and aggravate the pulverization of sub sieves.
1.5 failure caused by high intake water and oil gas
The air source at the front end of the nitrogen generator is equipped with multi-stage filtration facilities and drying facilities. This set of equipment mainly includes the air source purification system composed of cold dryer, over efficiency filter, alumina heating dryer and precision filter.
The filter element and alumina ceramic ball in the gas source purification system need to be replaced regularly. The damage or untimely replacement of the filter element will lead to water and oil gas in the gas source, but water and oil are the most important factors affecting the quality and service life of molecular sieve.
1.6 the top cylinder is not tight
Low pressure of instrument air, cylinder damage and low material level of nitrogen generator are the reasons for the top cylinder not to be pressed tightly. When the top cylinder is not pressed tightly, the cylinder will no longer restrict the molecular sieve. The air flow will give the molecular sieve more space to move, increase the impact force between molecular sieves, accelerate the pulverization of molecular sieve, seriously affect the firmness of the internal structure of the equipment, and aggravate the damage of the internal components of the equipment.
1.7 broken filter screen and coconut mat
Due to the impact of air flow and molecular sieve for a long time, the middle part of filter screen and coconut mat was damaged, resulting in molecular sieve falling into the tank bottom and leaking with the oxygen enriched discharge pipe. If the damaged filter screen and coconut mat are not replaced in time, it will form a vicious circle, affect the purity and flow of product gas, and seriously affect the stability and safety of equipment operation.
