Cryostar’s latest 6-stage fuel gas compressor model CM6-200 has been successfully commissioned and tested on the first LNG Carrier fitted with XDF propulsion.
Cryostar’s latest 6-stage fuel gas compressor model CM6-200 has been successfully commissioned and tested on the first LNG Carrier fitted with XDF propulsion. The 180 000 m3 LNG vessel, delivered last month from SHI in South Korea, was the first of its kind to be delivered to an Owner. The vessel is equipped with WinGD X62DF main engines and Wartsila 34DF gensets. The compressors were designed to be able to ably manage the different fuel gas requirements for each engine type.
Although the configuration of machinery and systems represented something of a prototype for XDF, the gas trial was passed successfully with some minor tuning of control loops, allowing the system to operate as planned, for all engine loads up to the required 4 ton/hour. All alarm and safety functions performed as planned and load adjustments as well as full engine trip was successfully handled over a period of 11 days.
A wider than usual tank pressure range and very high methane content in the boiloff was managed without issues, while the full design fuel gas pressure was achieved. Higher inlet temperatures were also well handled, providing a very forgiving solution for the Cargo Engineer when handling heel-out or other extreme cases.
These ground-breaking machines follow in the footsteps of the highly successful 4-stage compressors fitted to a large proportion of the DFDE and TFDE vessel fleet.
Simple and oil-free
The integrally geared machines boast 6 compression stages in a triangular arrangement on both faces of the gearbox. Oil-free operation is assured, especially important when coupled with a reliquefaction plant. The skid mounted unit incorporates the lubrication, sealing and flow-control elements of the system, to make installation as simple as possible. Water inter- and after-coolers assist by reducing the power consumption while increasing the operation range. The current model line-up covers both X52DF and X62DF engine designs.
High speed shaft vibration and bearing temperature values remained below the acceptable thresholds for all operating cases demonstrating the robust behaviour of this centrifugal compressor. Seal gas consumption was in line with expectations set during the design stage.
Partner of choice
A total of sixteen CM6-200 compressors have been delivered to date and are currently being installed on vessels under construction, with a further 12 units on order, showing Cryostar to be the partner of choice for XDF propulsion.
Read the article online at: https://www.lngindustry.com/liquid-natural-gas/01092017/another-first-for-cryostar/