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 Natural Gas is typically sourced long distances from consumers. For shorter distances (less than3000 km), transport by pipeline is generally used. For longer distances, it is more economical to transform the Natural Gas into Liquefied Natural Gas (LNG) for transport. One cubic meter of LNG is equivalent to 600 m3 of Natural Gas, making the volume to be transported much more attractive.
Bulk transportation of LNG is generally done using ocean-going LNG Carriers. This allows transport from the LNG loading terminal to the LNG receiving terminal. The receiving terminals have storage and vaporisation systems to allow Natural Gas to be fed into the local gas distribution system as required, according to consumption.
Since natural gas liquefies at cryogenic temperatures, i.e. temperatures well below -100°C, there is continuous boil-off of a small portion of the liquefied natural gas during transportation and storage This is termed natural boil-off gas (NBOG). Specialised equipment is required in order to handle this boil-off on both land and marine storage facilities. |
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The Applications
LNG Carriers
Cargo Handling and Fuel Gas supply systems
Cryostar has suitable equipment for LNG carriers of all propulsion types and vessel capacities. In addition, the engineering of different fuel gas supply systems can be undertaken.
Reliquefaction
Vessels which do not consume the natural Boil-off gas require a means to maintain safe cargo tank conditions and recover the NBOG. Cryostar’s famous EcoRel reliquefaction plants have been fitted to the world largest LNG carriers, Qatargas’ Q-Max series of vessels.
Regasification
For installation onboard regasification vessels or FSRUs. Cryostar has plants designed to use either steam or seawater as heating medium.
Land-based
Reliquefaction
Storage tanks which are used for long-term storage benefit from the installation of reliquefaction plants which can recover the natural Boil-off gas and return it to the tanks, allowing a zero send-out strategy to be followed.
Return Gas Blowers and BOG Compressors
Cryostar’s proven single stage compressors are used as gas blowers or multi-stage compressors for BOG compressors either designed according to our standard or in API 617 execution. Together with BOG compressors, BOG recondensing systems may be provided.
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The Equipment
Cryogenic Compressors
Electric motor or steam turbine driven single-stage or multi-stage cryogenic compressors complete with lube oil system, seal gas system, and accessories. These units can handle any type of cryogenic gas.
Heaters & vaporizers
Shell and U-tube design, all stainless steel, directly heated by saturated steam. The equipment consists of a single pass shell with stationary head, fully welded to the U-tube bundle. They are intended for cryogenic applications.
LNG Pumps
Cryostar offers a wide range of centrifugal or reciprocating cryogenic pumps available for LNG applications.
N2 Companders
A Cryostar design first delivered in 1996, this machine type combines of compressor and expander stages on the same gearbox and frame to produce the cold power required for liquefaction processes. |
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Processes
BOG Reliquefaction
Cryostar’s patented reliquefaction processes are based a Brayton cycle with nitrogen as an inexpensive and safe cooling medium. A compander produces the cold power and cryogenic heat exchangers are used to return the BOG to liquid form for return the storage tanks Full in-house process engineering, mechanical design as well as rotating machinery manufacture allows optimum matching of equipment to process.
LNG Regasification
Cryostar’s modular skid-mounted design is offered using one of three process, using steam or seawater as the heating medium.
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