Demanding valve specifications are par for the course with LNG megaprojects. However, when Severn Glocon was commissioned for a valve that could stroke across a distance of 18” with a plug weighing more than 1 tonne in less than 2 seconds, a truly innovative approach was required.
Customer specifications for the compressor bypass control valve demanded that noise levels should be lower than 82 dBa. Initial calculations indicated that in order to achieve this, velocity would need to be limited to 1/3 of sonic (0.3 mach).
Achieving this with a traditional control valve would require an outlet of 64”. Such a valve would have been a global first, and the customer was reluctant to consider this option. So the engineering team decided to tackle the challenge from a different perspective. They discovered that while the noise reduction required a 64” outlet, the flow coefficient could be controlled by a 36” valve.
Following this discovery, the engineers designed a 36” angle valve fitted with a 2cc low noise trim. Then a 36” x 64” diffuser was bolted directly to the valve outlet. Three large steel baffle plates inside the diffuser controlled the flow, enabling outlet velocity to be maintained at lower than 0.3 mach, ensuring all customer requirements were met.
More information about this project is available via the link: http://www.severnglocon.com/wp-content/uploads/SG-A4-1pg-Casestudy-LNG-Australia.pdf