Liquefied Gas Carrier

Home page||| LNG handling ||| LPG handling||| Other Gas products||| Fire & Safety||| Emergency response |||

The compressed natural gas (CNG) emerging as new gas technologies - CNG carriers

Transporting The Compressed Natural Gas (CNG): Compressed Natural Gas (CNG) has been developed as a shipping concept, relying on the high pressure containment technology used in conventional pressure vessel CNG storage and in pipeline systems to provide a form of concentrated gas storage which can be fitted onboard ships.

The CNG concept that has been around for a long time, seeks to offer savings by removing the need for the expensive onshore refrigeration trains required for LNG. However, CNG still needs separate gas conditioning and process systems to get the production gas segregated and suitable for transportation. A separate LPG processing and transportation system is also needed.

Although gas demand is growing, a simple development approach, with appropriately lower CAPEX and OPEX, is required to serve the smaller or “stranded” reserves. Hence, there has been a re-emergence of CNG proposals.

Processing is still required to condition the natural gas for shipment as CNG. Condensates, NGL’s and water are removed from the product before it is able to be compressed for storage in marine transportation containers. Like LNG, the LPG’s are processed and shipped separately.
LNG ship at sea
Fig:LNG carrier underway

Proponents of CNG have tested various combinations of pressure and temperature in an attempt to achieve optimal volumetric efficiency compared to containment system mass and cost. It is reported that CNG technology offers refrigerated compressed storage systems typically operating at 1800 psig at -20°F (-29°C), or pressure only systems operating at 3000 to 3600 psig at atmospheric temperatures in order to achieve compressed volumetric storage ratios in the order of 250 to 300 times the natural gas density at STP.

Yet, CNG systems have not yet entered full commercial development. Equipment development and economic costs are some of the major hurdles being addressed by various groups attempting to develop this technology, over the past 10 years.

The practicality of the proposed patented process solutions and offloading the CNG product from storage, at the required volumetric ratio levels previously mentioned, are proving to be energy intensive and time consuming to realize. The energy value of the production gas is not realized at market. Commercial implementation of this technology has been slow to emerge as there are no compelling economics.

In general, the largest vessel designs proposed will deliver 0.7 to 1.0 BCF of CNG product. Published figures concerning their economic realm of operation appear to place CNG ships in coastal or regional, as opposed to mid or trans-ocean service.

Related article:

Benifits of compressed gas technology

Transporting economically viable compressed gas liquids from remote fields

Advantages of the dual fuel diesel electric propulsion & crew training

Increased Cargo Capacity for LNG ships & Advantages of the dual fuel diesel electric propulsion

Procedure for transporting remote gas

Defining various gas carrier types

Fuel flexibility of LNG ships

LNG ship spillage risk

LNG shipment

Initial Cool Down of cargo tanks

Leaks on the Cargo System, Continuous Flow - how to prevent

LNG tank leaks and immediate action by gas carriers

Leaks from a Loading Arm due to Tidal or Current Effects

Minor or major leaks from LNG tanks

Procedures for LNG cargo loading

Procedures for LNG cargo discharging

// Home page/// LNG handling /// LPG handling/// Sea transport /// Gas products///

Cargo work ///Fire precautions ///Health hazards ///Safety Precautions

///Emergency response ///

Copyright © Liquefied Gas All rights reserved.

The content published in this website are for general reference only. We have endeavoured to make the information as accurate as possible but cannot take responsibility for any errors. For latest information please visit . Any suggestions, please Contact us !

///Links &Resources // Terms of use/// Privacy policy///Home page///