When it comes to sustainable, clean, and renewable energy sources, Biogas has become increasingly popular due to its potential to transform the energy landscape through the harnessing of the energy potential of organic waste streams. But, the transition from raw waste materials to high-quality biogas is challenging. That’s where renewable energy biogas purification with the PSA / VPSA system comes in.
These remarkable advancements along with the usage of varied molecular sieves, can help transform the renewable energy industry scene. Today let us explore these two bio gas purification processes in detail and understand their differences and similarities.
Biogases are a type of gas formed when organic material, such as food waste or agricultural residues, cattle dung/municipal solid waste, sugarcane press, sewage treatment plant waste, mud, etc., decomposes in an oxygen-deprived environment, like in a compost heap or swampland.
This process is analogous to the recycling process of nature. The composition of bio gas is primarily composed of two components: methane, the positive component that can be used for energy purposes; and carbon dioxide, the harmful component.
Additionally, biogas may contain impurities or fillers, such as hydrogen sulphide, and a small amount of water vapor, which must be removed before it can be used to produce clean energy.
Though biogas is a fantastic well-known and accredited source of renewable energy, it's not always clean for immediate usage as it is produced by the active/anaerobic degradation of organic matter. When biogas is created in a bio gas plant, it contains many impurities and harmful and unnecessary particles/components/impurities that need to be filtered out before use. Thus, the purification process is essential to remove any impurities like moisture, carbon dioxide, hydrogen sulfide, etc.
When the purification process is done using molecular sieves, it can help rid the biogas mixture of different and numerous impurities by capturing them in their selective strainer structures and providing clean and pure methane gas as an end-product.
Molecular sieves can be recruited in processes such as PSA and VPSA to create biogas that is highly purified in nature and prepared to be reconstructed into clean energy ready for use in homes and industrial settings.
If you're looking for a system to purify your biogas, PSA/VPSA model is the way to go. It's a specially designed gas separation system that uses adsorbent to separate the gas. Adsorbents are like molecular sieves, with a tiny pore on their surface that allows them to selectively adsorb molecules like Co2 and N2 under a certain pressure.
Once it's adsorbed, it's regenerated by being depressurized. These PSA systems use this process to produce the purified methane-enriched gas over and over, repeating the process over and over. The process of biogas purification increases the concentration of methane and decreases the concentration of carbon dioxide in the biogas, resulting in increased calorific value.
The materials used for the adsorbent layer are activated carbon (PC) and zeolite (5a), both of which have been shown in research, to work best at the pressures and compositions tested.
Activated carbon molecular adsorbs mostly CO2 and CH4 and is placed at the bottom of the column for the feed inlet.
Zeolite, on the other hand, adsorbs N2 and carbon molecular and is placed on top of activated carbon. The length of each layer that corresponds to the carbon to zeolite ratio, is a key factor in the PSA/VPSA system.
The adsorption cycle of the pressure swing system is very complicated, as there are many steps in the cycle and interactions between the stages that undergo different operations. The purity of the VPSA system is higher due to the very low process gas flow-rate and the smaller plant size.
PSA and VPSA are both biogas cleaning methods, but they differ significantly in terms of the conditions under which they are performed.
Pressure Swing Adsorption/PSA- This method mainly works by varying the pressure in the process. The biogas goes through biogas beds filled with a special material called molecular sieve. The molecular sieve traps the unwanted gases in the biogas. When the molecular sieve is full, the pressure changes, and the unwanted gases are trapped and released. The process is repeated with two biogas beds as a tag team.
Vacuum Pressure Swing Adsorption/VPAS- On the other hand, VPSA uses vacuum power capabilities. When the pressure is minimized/reduced (for example, in a vacuum environment), the sieves collect the particulates or impurities. When they are full, the pressure returns to normal and the particulates are discharged out of the system.
Here are some of the top advantages of biogas:
With the increase in the advantages of biogas combined with the help of systems like PSA and VPSA, we're turning biogas into a cleaner and more powerful energy source. Make sure to use the best-quality, selective filters, molecular sieves for your needs, that can capture impurities, to make sure the process is efficient and useful.