Reimagining flow control for efficient, low-noise LNG production

Liquefied natural gas (LNG) production relies on precise flow control to maintain stable and efficient operations. While the industry has matured significantly over the past 50 years, many facilities still depend on valve technologies that can create operational challenges when managing varying feed gas conditions.

Feed gas is often supplied from multiple sources, each operating at different pressures and flow rates. These variations place significant demands on inlet flow control valves, affecting rangeability, stability and overall plant performance. Recent advances in valve design are helping LNG operators address these challenges while improving efficiency and reducing operational risks.

Noise remains a significant challenge across LNG production facilities. Compressors, pumps, turbines, heat exchangers and venting systems all contribute to overall site noise levels. While some equipment can be enclosed or insulated, controlling noise generated by valves is often more complex.

As control valves regulate flow, rapid changes in gas velocity, pressure and direction create turbulence within the valve and downstream pipework. These conditions can generate vibration and elevated noise levels that affect both equipment performance and the surrounding environments.

The issue has become increasingly important as industrial facilities and residential areas are located closer together. In some cases, noise generated during LNG loading and unloading operations has led to complaints from nearby communities, highlighting the importance of addressing noise at its source.

IMI previously supported a major LNG producer in the Caribbean operating four liquefaction trains with a combined capacity of approximately 11.5 million tonnes of LNG per year.

The operator identified challenges with its feed-gas flow-control valves. The feed gas line had already been sized at 24 inches, while the specified linear-motion globe valve would have required a significantly larger 36-inch valve to meet flow coefficient (Cv) requirements.

To address this, IMI developed a new approach based on a quarter-turn ball valve design. The solution combined the valve's inherently higher flow capacity with a customised multi-stage trim incorporating patented DRAG™ technology, originally developed to manage high-pressure drops in severe-service applications.

The resulting dBX Shield™ rotary control valve was designed to improve flow control performance while minimising issues associated with pressure fluctuations, velocity changes and excessive noise.

Feed gas control applications typically require multi-stage trim designs, making them well-suited to DRAG™ technology. Integrating this technology into a trunnion-mounted quarter-turn ball valve represented a significant design advancement.

Compared with traditional globe valve solutions, the design offers:

Advances in additive manufacturing have further improved the design. The DRAG™ trim element can now be optimised more efficiently, allowing design refinements without major changes to the overall valve architecture.

Today, the dBX Shield™ valve can reduce noise levels significantly in suitable applications, in some cases achieving levels as low as 60dB.

Following routine inspections and asset integrity assessments, the LNG producer replaced an existing linear control valve on one feed gas line with a 24-inch reduced-bore dBX Shield™ valve.

The upgrade delivered improvements in:

Subsequent inspections and performance reviews led to additional orders for deployment on further liquefaction trains within the facility.

IMI has been investigating and applying additive manufacturing technologies since 2010, particularly for the production of DRAG™ trim components.

Additive manufacturing provides several benefits, including:

The technology is widely adopted across industries such as aerospace, medical, automotive and industrial manufacturing, where complex component geometries are required.

Within IMI, additive manufacturing supports the production of advanced flow control components that would be difficult or inefficient to manufacture using conventional methods.

The gas industry continues to focus on reducing fugitive emissions in line with standards including:

Fugitive emissions can occur through static and dynamic sealing points within valves. Quarter-turn valve designs generally offer strong sealing performance throughout their operating life, making valve selection an important consideration as operators work to reduce emissions and improve environmental performance.

Further information on these standards is available from the International Organization for Standardization (ISO).

More than 160,000 DRAG™ trims have been installed worldwide in severe-service control applications, alongside over 14,000 isolation valves used in critical service environments where safety, reliability and performance are essential.

To maximise the benefits of additive manufacturing, IMI developed a specialised DRAG™ flow control element geometry that enables efficient production while overcoming machine size limitations.

The trim is manufactured from Inconel 718, selected for its suitability for both additive manufacturing and demanding operating conditions. The design allows each trim to be engineered to meet specific customer process requirements while maintaining key valve capabilities, including:

The valve delivers rangeability of up to 1000:1 while managing noise, velocity and kinetic energy in accordance with recognised control valve sizing methodologies.

For LNG feed gas and gas pipeline applications, this approach can reduce infrastructure requirements, eliminate the need for multiple valves in certain installations and deliver significant weight savings compared with traditional globe control valve solutions.

Explore IMI's flow control solutions for demanding process applications:

This article discusses potential operational benefits that may be achieved through the application of advanced valve technologies. Actual performance will depend on operating conditions, system design and application-specific requirements.

A version of this article was originally published in LNG Industry magazine in August 2024