PSA Hydrogen Unit

Hydrogen is the most abundant element in nature with various applications in industry. Hydrogen can be found in most substances such as water, fat, oil, hydrocarbons, acids, ammonia, disinfectants, etc. This material is widely used in oil and gas, food, pharmaceutical, metal, chemical, ammonia production, glass making, electronics, analysis devices, etc. industries. Also, hydrogen is used as a clean fuel of the future.

Various processes are used to produce hydrogen in the industry, some of which are:

• electrolyze
• Methane reforming
• Cracking of heavy hydrocarbons
• Cold plasma
• PSA (Pressure Swing Adsorption)

PSA process is used to purify hydrogen to reach the desired purity. In the following, we will briefly review this process.

Purification and purification process of hydrogen gas by PSA method

PSA (Pressure Swing Adsorption) process can be used to recover and purify hydrogen from a mixture of different gases. Because the gas entering the towers is a combination of different gases with different mass percentages, different adsorbents are used in separate layers for better purification.

Absorbent materials used in absorption beds are usually: active alumina, active carbon, silica gel and Molecular sieve. Due to the size of different holes, specific surface and different surface properties, these materials have different absorption ability compared to the materials in the input gas composition. Active carbon is used to absorb oils, silica gel is used to absorb hydrocarbons, Molecular sieve is used to absorb moisture, CO, CO2 and active alumina is used to absorb moisture.

The equipment used in the process includes the input gas tank, purification towers, production hydrogen storage tank and storage tank for other gases. The gas enters the towers under pressure, after the absorption process is completed, the inlet valve to the tower is closed and the tower regeneration process begins. During the recovery process, absorption towers are usually depressurized and discharged in several stages. This cycle continues in all the towers, and finally, during this process, hydrogen with the required purity is produced.

The schematic of the process is as follows: