Innovating dry gas seals for the hydrogen economy
As we look for ways to cut carbon emissions in hard-to-abate industries, hydrogen has become widely recognised as one of the cleaner solutions to power the world.
Some petrochemical and process industries are already using hydrogen in their processes, but are also exploring ways to incorporate hydrogen into their applications. Routinely installed in centrifugal compressors used for gas transfer and distribution networks, dry gas seals are vital to these initiatives. Although the principles of dry gas sealing do not change with hydrogen, renewable hydrogen introduces certain dynamics that require innovative solutions. Understanding the challenges of hydrogen and intermittent production is essential to unlocking the potential of dry gas seals in the evolving field of hydrogen technology.
Mechanical seals for high-speed hydrogen gas compression
Designers look at various process parameters when selecting a dry gas seal for a centrifugal compressor. Operating speed is particularly pertinent for hydrogen service.
At its simplest, a centrifugal compressor uses rotating impellers to compress process gas. The lighter a gas, the faster the rotational speed needed to achieve the desired compression (assuming the compressor design is maintained). Most compressors are compatible with natural gas, which is primarily methane. Hydrogen has a molecular weight much lighter than methane and requires extremely high impeller-tip speeds to reach usable output pressures. This “need for speed” challenges the material-strength limits of many components, including dry gas seals.
A possible solution is to limit rotational speeds by implementing additional compressor stages. However, this often isn’t feasible due to rotor dynamic issues.
John Crane has a robust portfolio of dry gas seals. We also have experience with dry gas seal designs for high impeller-speed service.
As a member of Hydrogen Europe, one of the world’s leading hydrogen industry associations, John Crane is committed to accelerating the growth and deployment of the hydrogen economy. We are developing innovative materials and testing new sealing and support systems, including technologies that tackle hydrogen gas compression.
Mechanical seals for intermittent hydrogen production
Most hydrogen production taking place today is powered by fossil fuels, often natural gas. Although emissions-free hydrogen production is possible with renewable power sources like wind and solar, renewable inputs are notoriously inconsistent. If it’s not windy or the sun isn’t shining, compressors may have to start and stop multiple times daily — significantly impacting seal longevity.
At rest, a dry gas seal has two rings touching. They push off during operation as a thin layer of gas forms between the two rings, letting them run without contact. The more a compressor starts and stops, the more often the ring faces briefly touch, causing friction.
The actual duration of ring contact depends on the application. During start or stop, a single-shaft compressor may need up to five minutes of coast time, whereas an integrally geared compressor may only require 30 seconds.
Material selection for dry gas seals is critical to resisting friction. For example, a carbon-based primary ring can be relatively friction-tolerant due to carbon’s self-lubricating properties. However, a mating ring of silicon carbide or tungsten carbide may benefit from a specialised coating to increase durability when put into intermittent service.
John Crane has a legacy of pioneering dry gas seal technology. Our engineers are evaluating the effectiveness of various ring material pairings by using a test loop to simulate the conditions of intermittent service and investigating the effects of hard-soft or hard-hard dry gas seal ring combinations. For cases where contact is a concern, John Crane can directly incorporate a coating into manufacturing to prolong seal life, which in turn enhances reliability.
We also provide John Crane Sense®, which provides visibility to the remaining lifespan of a seal. Sensors embedded directly into the dry gas seal itself provide near real-time data for a comprehensive understanding of seal health. Data-driven insights into the current condition of a dry gas seal aid with maintenance planning, downtime prevention and, ultimately, enhanced visibility into a dry gas seal’s remaining lifespan.
Partner with the dry gas seal experts
A growing number of new players and projects are emerging in the low-carbon hydrogen space. There’s no standardised path forward, and the industry is exploring all technologies to power the energy transition.
At John Crane, we have extensive experience with hydrogen and more than 5,000 seals, filters, couplings and systems in service, enabling some of the world’s most innovative clean hydrogen facilities. As we endeavour to progress towards a net zero future, we are investing heavily in dry gas seal technology that will support the renewable hydrogen economy.
Contact John Crane today to discover how our dry gas seals can support your hydrogen initiative.