[ valves ]
Industrial perspective on liquid hydrogen valves
Storage and transportation of hydrogen in liquid state offers several advantages . Liquid hydrogen ( LH 2
) has a higher density and requires a lower storage pressure compared to gaseous hydrogen . However , hydrogen turns into liquid at -253 ° C , which brings its own challenges . The very low temperature as well as the risk of flammability make it a challenging medium . Stringent safety measures and reliability are thus a must when designing valves for this application .
By Fadila Khelfaoui and Frédéric Blanquet , Velan
LH 2 applications
Currently , LH 2 is being used and explored in various special applications . The aerospace industry uses it for rocket launching and transonic wind tunnels . Under the umbrella of big science , LH 2 is essential in superconductivity applications , particle accelerators and nuclear fusion . Recently , with increasing demand for sustainability , LH 2 has become of interest as a source of fuel for heavier trucks and ships .
Valves play an important role in the successful operation of these applications . Reliable and safe operation of valves that form part of the LH 2 supply chain ecosystem ( production , transport , storage , and distribution ) is a necessity . determining valve design risk assessment . For optimum valve performance , design features and material selection are of utmost importance . There are challenges to be overcome when handling LH 2
. One such challenge is the deleterious effect of hydrogen on metallic materials . Combined with the very low temperature , valve materials need not only to withstand the attack of hydrogen molecules ( some degradation mechanisms are still a subject of debate in the scientific community ) but must also be able to perform at that temperature for a long service life . The current knowledge of non-metallic material compatibility with hydrogen is still limited . This gap in knowledge must be taken into consideration when selecting sealing materials .
Working with LH 2 is not easy . There are numerous challenges associated with it . Leveraging 30 years of field experience and technical expertise in supplying high performance valves down to -272 ° C , Velan has been involved in pioneering projects and is unequivocally well positioned to meet the LH 2 challenges .
Design challenges
Pressure , temperature , and hydrogen concentration are the primary factors when
Tight sealing is another key design performance criterion . Under thermal gradients resulting from temperature differentials of up to 300 ° C between the LH 2 and the surrounding environment ( at room temperature ), different valve components expand and contract by varying amounts . This discrepancy can result in detrimental leakage of critical sealing surfaces .
Sealing tightness at the stem is another design consideration . The transition from cold to
26 Hydrogen Tech World | Issue 9 | April 2023