Methods to Reduce Molecular Sieve Powdering

Reasonably design the gas distributors for adsorption tower inlet and outlet to evenly distribute the gas, allowing compressed air to diffuse rapidly after entering the adsorption tower. This reduces the gas flow velocity and minimizes the impact on the carbon molecular sieve. If the gas distribution is poor, the compressed air will excessively impact the local carbon molecular sieve, and prolonged impact over the years is likely to cause powdering of the molecular sieve. During pressure equalization, the molecular sieves at the top and bottom of the adsorption tower are subjected to instantaneous impact. Therefore, the gas outlet distributor of the adsorption tower needs to be redesigned to reduce the impact on the top carbon molecular sieve during pressure equalization.

When loading carbon molecular sieve, compact it after every 30-40 cm of loading to eliminate excessive voids formed by natural pouring, and prevent "bridging" and large voids in the bed layer. It is strictly forbidden to fill the adsorption tower at one time and then vibrate it, as this makes it difficult to ensure a dense bed layer. When the adsorption tower is in operation, the gas flow will scour the bed layer, causing the carbon molecular sieve near the "voids" to move back and forth, leading to powdering.

Prolong the pressure equalization time. In traditional processes, pressure equalization is too fast, usually ending within 1-2 seconds. The adsorption pressure of domestic nitrogen generation equipment is generally ≥7 bar. When pressure equalization ends, the pressure in the adsorption tower rises rapidly by 3.5 bar, causing excessive impact on the local carbon molecular sieve. It is recommended to limit the flow in the pressure equalization pipeline to extend the pressure equalization time to 4-6 seconds.