EMISSION CONTROL
• Diverse applications : Beyond production , hydrogen offers a wide range of potential applications . In the transportation sector , hydrogen fuel cells are a promising alternative to internal combustion engines . Fuel cells combine hydrogen and oxygen to produce electricity , powering the vehicle with zero tailpipe emissions . Hydrogen can also be used in stationary applications for power generation , particularly when paired with renewable energy sources like solar or wind . Here , hydrogen acts as a form of energy storage , providing a buffer for times of low renewable energy production . Additionally , hydrogen has established applications in various industrial processes , such as steel production and ammonia synthesis . In these applications , hydrogen can help to decarbonize industries that are traditionally reliant on fossil fuels .
Unique challenges of hydrogen for valves
While hydrogen offers a promising path towards a clean energy future , it presents unique challenges for valves compared to traditional fluids , necessitating careful consideration of material selection , design features , and operational practices . 1 . Hydrogen embrittlement : One of the most significant concerns is hydrogen embrittlement . This phenomenon occurs when atomic hydrogen diffuses into the metal lattice of a valve component , weakening the material and increasing its susceptibility to cracks and fractures . Over time , this can lead to catastrophic valve failure , resulting in loss of containment and release of hydrogen under pressure . The risk of embrittlement varies depending on the specific material , its microstructure , and the pressure and temperature of the hydrogen gas being contained in the valve / pipeline . Stainless steels , a common choice for valves in many applications , are particularly susceptible to hydrogen embrittlement . To mitigate this risk , valve manufacturers are exploring alternative materials like nickel alloys ( e . g ., Monel , Inconel ) and special highpurity steels with enhanced resistance to hydrogen diffusion .
2 . Minimizing leakage : Another critical challenge is the minimization of fugitive emissions . Due to its small molecular size and high diffusivity , hydrogen gas can readily leak through even
Hydrogen zero emissions .
the smallest clearances . These leaks not only represent a loss of valuable energy but also pose a potentially major safety hazard . To combat this , valve designs for hydrogen applications often incorporate features like metal bellows or diaphragm seals , which minimize the potential leakage paths . Furthermore , advanced gland packing materials specifically designed for hydrogen compatibility , such as graphite-based or PTFE-based materials , are being developed to optimize leak tightness . Leak detection methods are crucial in hydrogen applications . Traditional methods like soap bubble testing are ineffective with hydrogen due to its low viscosity . Alternative methods , such as acoustic emission testing and tracer gas surveys , are becoming increasingly important for identifying and quantifying leaks in hydrogen valve systems .
3 . Designing for a flammable gas : Hydrogen gas is highly flammable and explosive when mixed with air in specific concentrations . This necessitates a rigorous approach to safety considerations in valve design , material selection , and operation . Valves for hydrogen applications are often designed to minimize potential ignition sources by employing features like spark-resistant materials ( e . g ., beryllium copper , aluminum bronze ) and avoiding components and materials which are prone to frictional heating .
4 . Material selection : Choosing the right material for hydrogen valves requires a balance of several key properties . Resistance to hydrogen embrittlement is paramount , as discussed earlier . However , the material must also possess adequate strength and mechanical properties to handle the pressures and stresses encountered in different hydrogen applications . For instance , valves used in high-pressure hydrogen storage require materials with exceptional strength and fatigue resistance , such as high-strength stainless steels ( e . g ., 316L , 347 ), nickel alloys ( e . g ., Monel , Inconel ), or titanium alloys . Furthermore , special considerations need to be taken for sealing mechanisms at high pressures . Traditional packing materials may not be suitable due to increased wear and tear . Alternative sealing technologies , such as metal-to-metal seals or self-energizing designs , are being explored to meet the demands of high-pressure hydrogen applications . Corrosion resistance is another important consideration . The specific choice of material may depend on the presence of impurities or contaminants within the hydrogen stream , as these can accelerate corrosion . For example , in applications where hydrogen is produced from steam methane reforming , the presence of sulfur compounds may necessitate the use of more corrosion-resistant materials like stainless steels or nickel alloys . The operating temperature can influence material selection , as some materials exhibit superior properties at specific temperature ranges .
5 . High-pressure hydrogen : The trend towards utilizing high-pressure hydrogen for transportation and storage presents
56 Valve World June 2024 www . valve-world . net