|LNG CUSTODY TRANSFER ANALYSIS
by Gas Chromatograph, Calorimeter and Densimeter
For LNG custody transfer it is now a common practice to determine the composition, density and WI by direct on line GC plus indirect lab analysis methods. A precise sampling according to the
SAMPLING PROBE and VAPORIZER
This superinsulation system is designed for providing thermal insulation by hight vacuum and enthalpy rise is controlled to be inferior of the subcooling degree.
In the vaporizer, LNG transformation in supercritical state eliminates fractionated vaporization which would generate fluctuations in the gas composition during
WI, composition and density measurements with better repeatability than 0.01 mj/m3 (ISO 6976) and reproductibility lab / process GC better than 0.15% (ASTM D1945)
SPOT & CHARGE SAMPLING SYSTEM
ISO 8943-1991: LNG continuous sampling method
ISO 8943-2004: draft of sampling with piston
EN 12 838: test to assess the LNG sampling
At vaporizer outlet sample gas is flow controlled and accumulated in constant pressure piston floating cylinder holder.
Purging device is operated for the removal of any residual gas from previous operations and the spot transportation containers are automatically charged every hour during the transfer in compliance with the fill and empty method Annex D of ISO 10 715.
Charge transportation containers at the end of transfer are automatically fed at 7 barg pressure within the same method.
The system processing is controlled via a solenoid valve actuator bus manifold and sampling sequence with alarm history are reported on the controller screen with data acquisition by keyboard. Customer data interchanges for maintenance acquisition and SCADA are supported by Data Highway through Modbus or other protocol.