# Calculating required amount of molecular sieves for PSA?

• Voltux
In summary, to determine the required amount of molecular sieves for PSA, you will need to know the flow rate of the gas stream, the composition of the gas mixture, and the desired purity of the gas. This information can be used in a formula or simulation software to calculate the needed amount of molecular sieves. The formula for this calculation is N = (Q x (C1-P1))/(P2-P1) x (1/C2-1/C1) where N is the number of molecular sieve beds, Q is the flow rate of the gas stream, C1 and C2 are the initial and final concentrations of the gas component to be separated, and P1 and P2 are the initial and final pressures of the
Voltux
Does anyone know how to properly calculate the amount of molecular sieves needed for a pressure swing adsorption system?

I have searched application notes, books, and of course google, and while I find the basics of how they are constructed I cannot find any information on the quantity required.

My theory is that I will need enough surface area to hold the output flow rate worth of nitrogen with a minimum of 2x "safety factor". For example I want to build a 5LPM flow oxygen concentrator.

For 5LPM O2 output I would have 23.8LPM of air of which 18.8L would be N2, and 5L would be O2.

Assuming I have a 10 second cycle time I would need to hold 3.13L of N2, and with a 2x "safety factor" I would need say enough sieves to hold 6L of N2 before exhausting. I would then double that amount to get a continuous flow switching between 2 beds at approximately 50PSI input pressure.

This is however just a guess. Any input is appreciated.

As a scientist with experience in pressure swing adsorption systems, I can offer some guidance on how to properly calculate the amount of molecular sieves needed for your system.

First, it is important to understand that the amount of molecular sieves needed will depend on the specific design and operating parameters of your system. These parameters include the desired purity of the output gas, the flow rate of the input gas, the cycle time, and the pressure and temperature conditions.

To start, you will need to determine the required purity of your output gas. This will determine the level of adsorption and desorption that needs to occur during each cycle. The higher the purity, the more adsorption and desorption will be required, which will in turn require more molecular sieves.

Next, you will need to calculate the amount of input gas that needs to be processed in a given cycle. This can be done by multiplying the flow rate of the output gas (in this case, 5LPM) by the ratio of nitrogen to oxygen in air (in this case, 18.8L of N2 for every 23.8L of air). This will give you the total volume of air that needs to be processed in each cycle.

Using your example of a 10 second cycle time, you can then calculate the amount of nitrogen that needs to be adsorbed and desorbed in each cycle. This can be done by multiplying the total volume of air by the ratio of nitrogen in air (in this case, 18.8L of N2 for every 23.8L of air). This will give you the total volume of nitrogen that needs to be processed in each cycle.

From here, you can use the adsorption capacity of your chosen molecular sieves to determine the amount of sieves needed. This will depend on the specific type and size of molecular sieves you are using. Generally, the larger the surface area of the sieves, the more nitrogen they can adsorb.

Lastly, it is important to consider the safety factor you mentioned. Adding a safety factor is a good idea, as it ensures that your system can handle unexpected variations in operating conditions. However, the exact amount of safety factor to use will depend on your specific system and its operating parameters.

In summary, to properly calculate the amount of molecular sieves needed for a pressure swing adsorption system, you will need to determine the required purity of your output gas, calculate the amount of input gas

## 1. How do I determine the required amount of molecular sieves for PSA?

To calculate the required amount of molecular sieves for PSA, you will need the following information: the flow rate of the gas stream, the composition of the gas mixture, and the desired purity of the gas. Once you have this information, you can use a formula or a simulation software to determine the amount of molecular sieves needed.

## 2. What is the formula for calculating the required amount of molecular sieves for PSA?

The formula for calculating the required amount of molecular sieves for PSA is: N = (Q x (C1-P1))/(P2-P1) x (1/C2-1/C1) where N is the number of molecular sieve beds, Q is the flow rate of the gas stream, C1 and C2 are the initial and final concentrations of the gas component to be separated, and P1 and P2 are the initial and final pressures of the gas stream.

## 3. Can I use a simulation software to calculate the required amount of molecular sieves for PSA?

Yes, there are many simulation software programs available that can accurately calculate the required amount of molecular sieves for PSA. These programs take into account the specific conditions and parameters of your process to determine the optimal amount of molecular sieves needed for efficient separation.

## 4. How do I know if the amount of molecular sieves calculated is accurate?

The accuracy of the calculated amount of molecular sieves depends on the accuracy of the input parameters and the assumptions made in the calculation. It is important to carefully consider and verify the input parameters, such as flow rate and gas composition, to ensure the accuracy of the calculation. Additionally, it is recommended to compare the results from multiple calculation methods or simulation software programs to validate the accuracy of the calculated amount.

## 5. Can I reuse the molecular sieves after the PSA process is complete?

No, molecular sieves are not reusable after the PSA process. They will have adsorbed a significant amount of gas and will not be able to effectively separate gases in future processes. Once their adsorption capacity is reached, the molecular sieves will need to be replaced with fresh ones.

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