Measurement of Density in Custody Transfer Systems. (eBook)

Published Date

January 1975

Measurement of Density in Custody Transfer Systems. (eBook)

(Excludes any applicable taxes)

This paper discusses three techniques for measuring custody transfer density, all using prorietary techniques. (13pp)

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The principal LNG Custody Transfer measurements are cargo level and cargo density. Accurate capacitance level gauging systems developed specifically for the purpose have been in regular LNG base-load service for many years. The measurement of LNG cargo density is of equal importance because the value of the cargo is nearly proportional to density, which varies with the source of the gas, the duration and the conditions of transit and the temperature at which the cargo is delivered.

On a single route, variations of several per cent may be encountered. For various sources and route conditions, density variations may exceed 20%. For several important reasons it has become established practice to make the Custody Transfer measurements in the ship tanks. Measurement in the ship tanks permits determination of density, an opportunity which is lost after the cargo is mixed into the contents of the shore tanks. From simultaneous measurements of level and density in the static volume of liquid, the mass can be computed accurately and without actually transferring the cargo.

Measurements before and after transfer determine the delivered mass independent of pressure changes or heat transfer from piping and pumps. Measurement accuracy in several small tanks is greater than in a single large tank. The same instrumentation system can be employed for purchase at the source and for sale at delivery, and can be the subject of agreement by all parties to the transactions.

Three techniques for the measurement of custody transfer density will be discussed. All are being supplied by Foxboro/Trans-Sonics for LNG transportation projects.

Paper Delivered by:
RL Blanchard (Foxboro/Trans-Sonics Inc.USA)

Prepared for:
Gastech Paris 1975

For over 45 years, the Gastech Exhibition & Conference has been at the forefront of the international gas and LNG market. This world-renowned event is regarded as the most significant meeting place for gas and LNG professionals, where the global industry gathers to do business.

Gastech hosts major IOCs, NOC’s, global utility companies, EPC contractors, shipbuilders, pipeline companies, manufacturers, distributors, technology and service providers, all who play an active role in the global energy value chain.

Title: Measurement of Density in Custody Transfer Systems. (eBook)
Product Code: 4433g045
Published Date: January 1975

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