Materials And Coatings For Turbomachinery In Hydrogen Applications

Abstract

Centrifugal compressors are commonly utilized for hydrogen compression in refineries for critical applications, and a potential “Hydrogen Economy� to lowering the carbon footprint on a worldwide scale will require compression of hydrogen to even higher pressures. Provided that the temperature is kept below 200°C (392°F), relatively standard materials that are currently utilized in hydrogen compression and transportation can be utilized at pressures up to 69 MPa (10 ksi). There is an extensive service history of centrifugal compressors which utilize carbon steel casings in a hydrogen environment, and API 941 has recognized that standard carbon steel can be used at these conditions. Carbon steel is used for the pressure-containing components such as the process piping and the centrifugal compressor casing. Higher strength steels can be used for the rotating components provided that they have a maximum yield strength of 827 MPa (120 ksi). While this provides a method to compress the hydrogen for transportation and storage, the yield strength requirement limits the maximum performance of the compressor and results in the need for more compression stages or additional compressors to be utilized to achieve a desired storage or transportation pressure. Efforts are underway to find a material with a higher strength that it suitable for hydrogen compression.