| dc.description.abstract | Global demands for petrochemicals and green hydrogen usage are on the rise and are expected to continue for at least the next decade. Green hydrogen liquefiers are needed for the worldwide reduction of greenhouse gases and global commitments to net zero by 2050. Hydrogen is a long-term energy carrier and storage solution, and with renewable energy costs shrinking overall, green hydrogen production via electrolysis is increasingly becoming a viable solution. As a result, the demand for turbomachines to carry out cryogenic hydrogen services is growing. Radial inflow turbines, or turboexpanders, have been used in hydrogen-rich applications in the petrochemical industry since the early 1960s. Hydrogen, or hydrogen-rich gas applications, require special turbomachines. Oil-free solutions are preferred, with high peripheral speed designs and low operating temperatures (22 K is required for liquefaction). In this technical brief, the authors discuss turboexpanders designed for hydrogen service, featuring high enthalpy drop (head), high impeller tip speed, rotor-bearing system, material selection to avoid hydrogen embrittlement and material suitability for deep cryogenic temperatures. Turboexpander loads, varying from small friction to booster compressor or generator loads, are covered. In particular, the authors present the challenge of matching high flow coefficient booster impellers with low flow coefficient turboexpander wheels in hydrogen applications. | |
