Improving Biogas Purity: Methods Of Biogas Purification Through Chemical Absorption

Biogas, being a renewable energy source is mainly produced from organic matter and contains elements like methane, carbon dioxide, and traces of hydrogen sulfide. It is a great alternative to fossil fuel, but raw biogas needs to be treated before use since it contains high amounts of carbon dioxide which reduces its energy content and calorific value. It is important to purify biogas to increase its methane concentration to optimize its utilization as a fuel source.

Methods Of Biogas Purification Through Chemical Absorption

Various methods and techniques are to enhance the quality of biogas through chemical absorption, by using various techniques such as adsorption using molecular sieves, Pressure Swing Adsorption, and Vacuum Pressure Swing Adsorption.

These methods extract CO2 from the biogas and provide a purified stream with higher methane concentration by making use of the selective adsorption and desorption capabilities of different absorbents.

1. Pressure Swing Adsorption (PSA)

PSA is an advanced gas separation method which is Widely used in industrial applications, such as bio-gas purification plants. PSA works by changing the pressure within the adsorption bed, allowing for selective adsorption of the target gases and desorption of impurities.

It is a process by which carbon dioxide is adsorbed or desorbed by Molecular Sieve or Activated Carbon at varying pressure levels to separate CO2 from methane. Various adsorbents are used in this process including Molecular Sieve, Silica Gel, and Activated Carbon. Molecular Sieve is a popular choice for this process due to its low cost, large specific area, high pore volume, and high thermal stability.

2. Pressurized Water Scrubbing

One of the most common ways to treat biogas is by using pressure water. Pollutants such as CO2 and H2S can be adsorbed to a liquid solution efficiently using this process. Within the scrubber, the absorption takes place mainly on the packing media surface and happens when raw biogas enters the scrubber at the base of the column and moves up the column, while freshwater enters the column at the top and moves down the column over the packed bed. The packed bed, which is a plastic medium with a high surface area, allows for direct contact between the water phase and the gas phase in a counter-current absorption mode.

3. Removing Moisture From Biogas

It is necessary to remove excess moisture from the biogas, thus the gas cooling method is a simple way to capture moisture in biogas. As the gas cools, water vapor evaporates on the cooling coils, trapping it in a trap. Some amounts of Ammonia will also be removed in this process due to its high solubility in water and other soluble contaminants. High-performance and quality adsorbents are used to remove moisture and water vapor in this process which can efficiently remove moisture content from the biogas before usage and application.

Raw biogas cannot be used in its raw form and contains a variety of compounds aside from methane including H2s, N2, VOCs, H2O, and O2. To remove these contaminants various methods such as adsorption, water scrubbing, biofiltration, and refrigeration are employed. At present, the basic cleaning methods for biogas are absorption, Biofiltration, Water Scrubbing, and Refrigeration. 

If you're seeking high-quality adsorbents for biogas purification through chemical absorption, your search ends here. Since 1996, Molecular Sieve Desiccants has been a global supplier of premium adsorbents. We are recognized as an industry leader in providing top-notch moisture and oxygen solutions.