Emerging valve designs for high-performance lng liquefaction

The Liquefied Natural Gas (LNG) market has experienced sustained growth since the early 2000s. In 2000, LNG accounted for approximately 26% of global natural gas trade. By 2023, this figure had increased to around 45%, with continued upward momentum expected.

The United States is a key driver of this expansion, with liquefaction capacity forecast to more than double over the next five years, reaching approximately 169 million metric tonnes by 2027. While other major producers such as Qatar remain significant contributors, the trend underlines LNG’s long-term role in global energy supply.

This growth reinforces the importance of robust specification across LNG liquefaction processes, particularly in critical equipment such as valves used in feed gas dehydration systems.

Feed gas dehydration is one of the most critical stages in LNG production. The performance of molecular sieve systems used in this process is highly dependent on valve reliability, tightness, and operational consistency.

During operation, wet natural gas passes through vessels containing solid desiccant material, which removes water content. Effective dehydration is essential because any residual moisture can freeze during liquefaction, leading to blockages and potential damage to downstream piping and equipment.

Thermal regeneration cycles are required to restore the desiccant’s performance. Valves located at the top and bottom of dehydration vessels enable flow direction changes during these cycles. These components operate under demanding conditions, including:

These conditions can contribute to unplanned operational interruptions. Industry reports have highlighted the significant financial impact of LNG plant downtime. For example, analyst estimates suggest that even a few days of unplanned outage annually can result in multi-million-dollar losses, reinforcing the importance of correct valve selection and specification.

Rising stem ball valves (RSBVs) are widely used in molecular sieve systems due to their roto-translatory motion, which combines rotation and axial movement. This design supports operation under thermal cycling conditions and provides improved resistance to wear from solid particles.

Conventional ball and gate valve designs are typically less suited to this application due to:

Despite their advantages, RSBVs present operational considerations. Their more complex construction can result in:

These factors have led operators to reassess the total cost of ownership (TCO), particularly in environments with volatile operating conditions.

Correct valve specification in feed gas dehydration systems requires careful consideration of operating conditions and system design. Key technical requirements include:

Regeneration gas temperatures typically range from 200°C to 350°C, meaning valves are exposed to significant thermal cycling over their service life. Material selection, tolerance design, and sealing performance are therefore critical to long-term reliability.

As LNG production expands and operators seek improved lifecycle performance, alternative valve designs are being considered alongside traditional RSBVs. The focus is increasingly on compactness, maintainability, and reduced total cost of ownership.

Double eccentric segmented ball valves are designed to reduce friction through a cam-style motion that avoids continuous rubbing between sealing surfaces. This makes them suitable for demanding molecular sieve service conditions.

Key characteristics include:

These features can improve maintainability and reduce downtime in LNG dehydration applications.

Triple eccentric metal-seated butterfly valves are also gaining adoption in molecular sieve service. Their design enables sealing contact only at final closure, reducing wear during operation.

Key advantages include:

One example design is IMI’s MV series, which uses a one-piece body and integrated shaft-disc arrangement to improve mechanical integrity and simplify maintenance requirements.

As LNG infrastructure continues to expand globally, reliability in critical process equipment becomes increasingly important. Even relatively small components, such as valves, can have a significant impact on production continuity when operating in severe service environments.

Unplanned downtime remains a key cost driver in LNG production, with operational disruptions often resulting in substantial financial losses across the value chain. This reinforces the importance of selecting valve technologies engineered for high-cycle duty, thermal stability, and resistance to abrasive media.

Feed gas dehydration is a critical stage in LNG liquefaction, and valve performance is central to ensuring operational efficiency and plant reliability. While rising stem ball valves remain widely used, emerging designs such as double eccentric segmented ball valves and triple eccentric metal-seated butterfly valves offer alternative approaches that address challenges around maintenance, footprint, and lifecycle cost.

As LNG demand continues to grow, correct specification and collaboration between plant operators and equipment suppliers will remain essential to achieving reliable, efficient production.

More information on LNG process expertise.

A version of this article was originally published in Hydrocarbon Processing magazine in 2023.