How to judge carbon molecular sieve is out of work?
Time:2025-06-25
The methods for determining the failure of carbon molecular sieves include the following:
* Shelf life and performance degradation: The performance of carbon molecular sieves will degrade by approximately 5% annually. If the shelf life is long and the performance significantly decreases, regular maintenance or replacement may be necessary.
* Decreased nitrogen production: If the nitrogen production of the nitrogen generator significantly decreases, it may be caused by the aging of carbon molecular sieves.
* Decreased water removal effect: By detecting the moisture content in the treated gas or liquid, if a significant increase in moisture content is found beyond the expected range, it may indicate the failure of the molecular sieve.
* Slow adsorption rate: Under the same conditions, it is observed that the rate of water adsorption significantly slows down, with a significant difference compared to new molecular sieves.
* Difficulty in regeneration: After normal regeneration, it is found that its water removal ability has not been effectively restored when used again, or multiple regenerations are needed but the effect is still poor.
* Abnormal physical state: There are obvious physical damages such as breakage and pulverization, which may affect its adsorption performance.
What are the factors that affect the failure of carbon molecular sieves?
1、Quality of carbon molecular sieve
The higher the grade of carbon molecular sieve, the better its manufacturing process and material quality, resulting in a relatively longer shelf life.
2、Usage environment
* Temperature and humidity: High temperature and humidity environments can accelerate the aging process of molecular sieves and shorten their service life.
* Pollution level: If molecular sieves are exposed to oil pollution or other harmful gases for a long time, their adsorption capacity and performance will gradually decrease, affecting their service life.
* Working pressure: Excessive work pressure may cause damage to the structure of molecular sieves, thereby shortening their service life.
3、Usage frequency and load
Adsorption capacity: The more gas molecules adsorbed by the molecular sieve, the more saturated its adsorption capacity will gradually become, requiring more frequent regeneration processes, which will increase its wear and shorten its service life.
Running time: Long term continuous operation will accelerate the fatigue and aging of molecular sieves, especially under high loads.
4、Maintenance
Regular maintenance: Regular maintenance and upkeep of carbon molecular sieves, such as cleaning, regeneration, and inspection, can extend their service life.
Replacement cycle: According to the recommendations and usage of the equipment manufacturer, regularly replace aging molecular sieves to ensure the normal operation of the equipment and high purity of the gas.
How long does it take to replace carbon molecular sieves?
Under normal 24hour’s operation, the replacement cycle of carbon molecular sieves is usually 3-5 years. If used under better conditions, the lifespan can be at least 5-8 years. However, if the compressed air quality is poor, the replacement cycle may be shortened to 3-5 years.
Air adsorption dryers are familiar in the chemical industry, and their core components are adsorbents , such as activated alumina, molecular sieves, silica gel. They adsorb water and gas through a porous structure, and their performance affects the drying effect directly. As the adsorption regeneration cycle progresses, the adsorption capacity gradually decreases and needs to be replaced regularly to ensure stable system operation.
The replacement cycle is usually 3-5 years, but it needs to be adjusted based on the following factors:
1. Frequency of use: High frequency use will accelerate the saturation of the adsorbent, and the cycle needs to be shortened; Long term high load operation will accelerate the decline of adsorbent performance;
2. Environmental humidity: The higher the humidity of the inlet air, the greater the adsorption load and the corresponding decrease in lifespan; High temperature, high dust and other harsh environments may require early replacement.
3. Operating parameters: Abnormal pressure or increased dew point temperature may indicate adsorbent failure.
Meanwhile, during work, it is important to pay attention to the following matters:
1. Monitoring indicators: Regularly monitor the dew point temperature at the outlet, and if it continues to exceed the standard, check the status of the adsorbent.
2. Replacement operation: Thoroughly clean the adsorption tower during replacement to avoid mixing of new and old adsorbents; The filling should be evenly compacted to prevent air flow short circuits.
3. Selection matching: The new adsorbent should be consistent with the prototype number to ensure that the porosity and mechanical strength meet the requirements.
4. Regeneration inspection: After replacement, verify the regeneration effect and confirm that the heating temperature and cooling time are normal.
So how to choose the right adsorbent for an adsorption dryer?
1) Molecular sieve: It is a crystal structure with uniform pore size and strong adsorption ability for water molecules, especially suitable for precision industrial scenarios with dew point below -60 ℃. However, due to its low strength, it is easy to be pulverization under high-intensity compressed air impact, so it can only be used in small quantities in traditional twin tower adsorption dryers.
2) Activated alumina: It is a high-strength adsorbent and the most widely used adsorbent in adsorption dryers currently. It can withstand the high-pressure impact of compressed air without powdering. Excellent performance in moderate humidity environments, suitable for places with dew point below -40 ℃, with a regeneration temperature 30-50 ℃ lower than molecular sieves.
3) Silica gel adsorbent: It’s getting less and less in compressed air drying. It is only suitable for drying at room temperature and is used in pressure dew point environments of -20 ℃.
In terms of drying performance, molecular sieves are much stronger than activated alumina, but the replacement cost is higher. Therefore, before choosing which adsorbent, it is necessary to understand the user's requirements or expectations for dew point, so as to choose the best solution that can meet the user's requirements and reduce the cost of use.
