Necessity for LNG Energy Custody Measurement in China and How to Make It Credible

摘要

Recently several LNG receiving terminals have been built along the seacoast areas in China.Simultaneously some LNG terminals are in construction and a number of other terminals are in the schedule.Till now,most other LNG terminals are set the custody metering outlet the terminal after the LNG being regasified,and the natural gas metering is the volume measurement except for a few terminals.LNG unloaded from the vessel is level measurement and the onshore metering of LNG is used to contrast and check as a reference.While for the object metering method and essential measurement energy custody measurement is necessary.Firstly,this will ensure the veracity of the medium quantity; secondly,will differentiate independent function part measurement definitely and make interface clear to prevent dispute.So the factors to improve the precision and reliability of the energy measurement in each key links such as,LNG vessel measurement,LNG unloading measurement,processing boil-off gas measurement and regasified natural gas measurement shall be analyzed.The optimization methods to measure the temperature,the pressure,the level,the density,the medium components and the heating value are used.Then ensuring the measurement with suitable instruments of their accuracy,repeatability and reliability,the method to improve the parameter avoiding the error,and the system potential Uncertainty,optimum algorithm and program calculation,will be developed analyzed with details.