4-stage Gas Compressor - Cryostar

4-stage Gas Compressor
for Dual Fuel Engine Gas Supply on DFDE LNG Carriers
Electric motor driven four-stage
cryogenic/warm compressor, with
variable diffusor vanes on first stage,
complete with lube oil system, seal gas
system, and accessories.
Typically this machine delivers up to
5’500 m3/h of boil-off gas with an inlet
temperature as high as -20°C, at a
delivery pressure of 6.5 bar a.
The unit is installed on a single, rigid
skid, with bulkhead, bulkhead seal and
heavy-duty gearbox.
For marine applications full certification
is included.
Key Advantages of Cryostar 4-stage Boil-off Gas Compressors:
Compact, space saving arrangement
Simple onboard integration, and access for operation and maintenance.
Rigid heavy-duty skid
Proper stability of the motor/compressor arrangement, for trouble-free operation.
High efficiency and performance
Smaller motor sizes squeeze cost and assure economic operation.
Advanced, oil-lubricated bulkhead seal
Accessibility for shaft alignment, no sealgas consumption, reliability and safe operation.
Integrated local panel
Cabling and tubing done in the factory thus reduced installation cost for the shipyard.
Process Integration with the Cargo Handling System
Cryostar provides a combined, well-integrated package with the Gas Heaters/Vaporizers.
IAS Integration
As an option, serial link to IAS, or fully redundant integration with selected IAS vendor.

4-Stage and 2-Stage relative performances : discharge pressure & flow range
Pressure for 100% engine load
6.5 bara
Approximate curves
4.5 bara
~ < 2 bara
-120°C
-100°C -80°C -60°C
-40°C -20°C 0°C 20°C 40°C
Design Capacity & Rangeability
Recycle 4-stage Cryo 40 ~ 100%
Traditional 2-stage Cryo 25 ~ 100%
0 1’300 2’600 3’900 5’200 6’500 m3/h
4-Stage BOG Compressor operation envelope – key facts:
Full 6.5 bara pressure from -140 to -20 degC WITH NO SPRAY PRECOOLING REQUIRED !
HEEL-OUT OPERATION possible to DF engines
And also
Massflows down to 500 kg/h are possible
More than 4 bara at +40 degC
No VFD speed control
Limited recycling
Water cooling
No continuously running pumps for spray precooling
Retrofit of 4-stage compressor in place of 2-stage compressors is also feasible
Applications:
For LNG carriers,
as Fuel Gas compressor to maintain the cargo tank pressure while supplying boil-off gas as fuel to the dual
fuel engines and/or gas combustion unit during the voyage.
For land - based plants
these units are supplied as Cryogenic Compressors, without bulkhead and designed according to API617 if
required (with separate lube oil system for special purpose oil systems).
CRYOSTAR SAS - BP 48 - Zone Industrielle - F-68220 Hésingue - France
Phone: +33 389 70 27 27 - Fax: +33 389 70 27 77 - sales@cryostar.com - www.cryostar.com