PSA adsorption time

Thank you, hx－Qingfeng. The adsorption time you mentioned refers to the entire duration of the adsorption cycle, and I know that. What I want to ask is, for example, in the timeline example you gave, how are the times t1 and t2 determined? You can’t just say that as long as there’s space at this time, it’s fine, right? I think it has something to do with the adsorption capacity of the adsorbent and the intake air? Please give me some advice.

“In PSA, is it assumed that the adsorption of the adsorbate by the adsorbent occurs instantaneously? ” No ； Since adsorption and desorption occur simultaneously, the adsorption time refers to the time required to reach dynamic equilibrium under certain pressure and temperature conditions, as indicated by the constant level of the adsorbate at the inlet and outlet.

Q&A: I believe that mastering dynamic balancing is a process that combines theory and practice. Theory: The adsorption time specified by the manufacturers is not necessarily the optimal one; it is merely a reference value. By understanding the principles behind it, you will dismiss such times as unimportant. The key is to depend on the actual PSA operation conditions. Practice: I have a question – if the regeneration effect of the adsorbent is poor, then how should its adsorption time be calculated? For example, in pressure swing adsorption, a poor vacuum level can affect the effective adsorption capacity of the adsorbent bed, which in turn leads to poor regeneration of the adsorbent. Therefore, the PSA adsorption time can only serve as a theoretical reference value.

Blood pressure hasn’t been reduced enough； When vacuuming is performed, if the vacuum level is insufficient, the regeneration effect is poor.

1. It is determined based on the adsorption capacity of the adsorbent. 2. While ensuring product quality, the adsorption time should be extended as much as possible to increase the yield of the product

When setting the time, it is essential to ensure that the pressures at each step are balanced; thereafter, the adsorption time is extended according to the required product concentration. Taking the time on the 3rd floor as an example, this process should be the 8-2-3-V sequence, that is, a total of 8 columns are used, with 2 columns undergoing adsorption simultaneously, followed by 3 pressure equalization steps and 1 vacuum pumping step. The time steps are only T1 and T2. T1 time refers to the average first time, average third time, and final rise time, while T2 refers to the average second time and vacuum pumping time. When setting T1, a margin of 2–3S can be added while ensuring pressure balance across all towers; this time should represent the minimum value for T1 ； When setting T2, the shortest time should be sufficient to meet the vacuum level requirements. To improve the product yield while maintaining product quality, the T1 and T2 times can be appropriately increased. When product quality cannot be ensured in the shortest possible time, adjustments should be made to aspects such as processing volume, adsorption pressure, and desorption pressure. Two concepts: Adsorption time generally refers to the time required for the adsorption process in a single tower; in the example given, this is 4T1. Adsorption cycle: The time it takes for one tower to complete the processes of adsorption, desorption, and pressure increase; in some contexts, this is also referred to as cycle time or adsorption cycle time, which equals (T1+T2)*8

The adsorption time is generally determined by the capacity to adsorb impurities, the penetration time of the adsorbent, and the standard (purity) to be achieved. Adsorption cannot actually be seen to occur in an instant. The so-called adsorption equilibrium is actually a dynamic equilibrium; that is, at any given moment, the amount of substance absorbed by the adsorbent is equal to the amount released, thus achieving a dynamic equilibrium.

How is the adsorption time determined and calculated?