Maximize Hydrogen Plant Efficiency With More Reliable Components

The bane of any hydrogen plant operation is downtime. Though necessary for maintenance, the best way to counter the losses incurred by downtime is to reduce their frequency. Although taking care of sensitive equipment is important and knowledgeable workers trained in their tools will reduce wear, durable components specifically selected for the unique challenges of hydrogen will keep a system up and running. To understand how to maximize hydrogen plant efficiency, it’s as important to discuss the underlying chemical and physical properties of the molecule as furnishing the components best fit to handle its conditions.

Accounting for Hydrogen’s Uniqueness in Hydrogen Plant Efficiency

Hydrogen has many unique properties that must be accounted for in any system. Most notable is its size: with an atomic radius of just 53 pm, hydrogen is difficult to contain. Its small size and general reactivity to many common metals also lead to embrittlement. Under high pressures, hydrogen’s solubility into the surrounding metal increases, which provides a vector for material creep and crack propagation. High-nickel concentration 300-series (iron-nickel-chromium alloys) stainless steels are able to introduce austenitic structures into the workpiece below the critical eutectoid temperature of mild steel; 316/316L austenitic steel possess excellent qualities for resistance to hydrogen embrittlement. These high-nickel stainless steel alloys are also able to better resist the transformation of austenitic to martensitic structures, which contributes to a weakening of the overall metal due to an increase in strain energy and provides localized pockets for hydrogen trapping as density decreases. The Swagelok Alternative Fuel Source Ball Valves are an excellent option for hydrogen plant efficiency; constructed from 316 stainless steel body and end connections, they are able to operate at pressures up to 6000 PSIG.

Hydrogen of course is not only the smallest atom, but it is also the lightest, and its incredibly minute molecular weight allows it to accumulate in the roofs and ceilings of closed facilities. Under normal circumstances, buoyancy is a positive attribute as it carries fugitive emissions away from operators and will not displace a breathable atmosphere. The concern with hydrogen accumulating in a closed container is due to its high flammability, which is able to combust rapidly in single-digit atmospheric mixtures. Furthermore, hydrogen fires burn at an exceptionally high velocity due to its mass and high diffusivity. 

One final complication is in hydrogen flame detection. Burning hydrogen emits no odour or smoke, and the dim blue colour of the flame is nearly invisible in the presence of ambient lighting. 

The Greatest Fugitive Emission Vector Is via Valve Stem

Valves are the greatest source of fugitive emissions with a near supermajority of leaks occurring at the valve stem. However, there are a variety of ball valve designs that can assist with leakage vectors. An important designation for any valve in a hydrogen plant is API 641 certification. The certification is granted to any quarter-turn valve that is able to withstand a battery of tests while maintaining a rate of emission less than 100 ppm. Stressors include temperature cycling and hundreds of open-close cycles while held at a constant high pressure. Polyetheretherketone, also known as PEEK, is a semi-crystalline thermoplastic that is able to withstand the distinct chemical characteristics of a pure hydrogen environment. For valve stems, Nitronic 50 is rated for hydrogen applications up to 20,000 PSIG.

Forming Strong Seals With Tubes And Fittings

Though tubing does not have the emission notoriety of valves, it is important to note how hydrogen can interact with the component considering the sheer preponderance of it in any industrial design. Hydrogen’s small size and high diffusivity endeavors it to escape via the smallest leak paths. Surface defects in tubing provide a likely path for escape; notably, the larger the outer diameter of the tube is, the greater the chance of sealing failures. To counteract the potential for leakage at seal points, heavier walls are recommended for tubing in hydrogen processes. The thicker walls provide more resistance to a ferrule during installation, allowing for any surface defects to tightly grip the tubing and coin out imperfections. Additionally, a tube support system helps to restrict the movement of components to prevent abrasions or punctures with the surrounding environment.

Ferrules form their own contribution to leak prevention. The FK Series includes a set of front-facing and back-facing ferrules. The front ferrules work to create a leak-tight seal, while the back seal enhances tube grip and dampens against vibration. The nut-body coupling as well as both sets of ferrules consist of 316 stainless steel alloys to protect against hydrogen embrittlement, reducing diffusivity into the material to lengthen product service life.

Small Emission Prevention Adds Up

Any point in a fluid system is a potential leakage vector. While the potential for emissions at any one of these components is potentially small, the prevalence of these components in the greater system offers a chance to reduce emissions and increase efficiency:

• Pressure relief valves: Failure can occur during reseating or if the valve fails to maintain the seal pressure near the set pressure.
• Flanges: In addition to size and pressure classes, the sealing face must fully interface with the tubing adapter for different face styles such as flat, raised, RTJ, and tongue-and-groove. 316/316L stainless steel material further inhibits fugitive emission release.
• Welding: Connectors can be welded, provided the connection is not necessary for safety, maintenance, or modular design. An orbital weld system could be an option for repeatable, high-quality welds.
• Sampling systems: A closed loop sampling system can return purged fluid to the inlet.

Proactive leak detection and repair will prevent maintenance downtime, avoid costly fines, and increase your industrial yields.

Maximize Hydrogen Plant Efficiency With Edmonton Valve & Fitting

To best increase hydrogen plant efficiency, all manner of leakage vectors must be considered and minimized. However, the number of components to consider results in an extremely daunting task. Whether your operation is in need of compressed gas leak detection to reduce costs and protect your operators or a new API 641-compliant component, consult with our Field Advisors to map out the solution to all of your hydrogen needs.