Cleaning: Before compressing hydrogen, the gas must be purified and free of impurities, including water vapour, oxygen, and hydrocarbons, which can cause safety hazards. Molecular sieves or other filtration systems are used for purification.
Cooling: Hydrogen is typically cooled to near room temperature (around 25 degrees Celsius) to facilitate compression and reduce the risk of ignition caused by high temperatures. This is achieved through heat exchangers or refrigeration units.
Compression: Hydrogen compression involves using specialised compressors designed for high-pressure gas handling. There are two main types of compressors used:
- Reciprocating compressors: These compressors use a piston to compress the gas in a cylinder, similar to the piston in an engine. They are suitable for low to medium pressure compression.
- Centrifugal compressors: These compressors use a high-speed rotating impeller to increase the hydrogen's pressure through centrifugal force. They are used for higher pressure compression.
Multi-stage compression is often used, where hydrogen undergoes multiple stages of compression to reach the desired pressure. Intercooling between stages is employed to remove the heat generated during compression.
Storage: Compressed hydrogen is typically stored in high-pressure vessels or tanks suitable for containing the gas safely. These vessels are made of strong materials such as steel or composite materials and designed to withstand the pressure of compressed hydrogen.
Precautions: Hydrogen compression requires strict adherence to safety guidelines due to its high flammability and potential for explosions. Adequate ventilation, leak detection systems, and safety protocols are implemented to minimise risks during the compression process.
