A PRACTICAL APPROACH TO MODELLING LNG TRAIN DESIGN FOR MINIMIZING MEASUREMENT AND ALLOCATION UNCERTAINTY

摘要

Our ability to measure accurately has formed the basis of trade in all industries. As a consequence, the performance of measurement systems will affect the profitability of any business. In the Oil and Gas Industry measurement systems are used for fiscal and custody transfer purposes, for process plant operations and for plant efficiency monitoring. It is of great importance therefore that these systems are engineered, operated and maintained to industry standards and within equipment specifications. This paper highlights the implications of measurement uncertainties on LNG product allocations and how, through a study of these uncertainties and the implementation of a Measurement Upgrade Enhancement Project, the final Allocation Uncertainty was more than halved. The study addressed each of the metering elements associated with the allocation process and identified which of these had the greatest impact (and/or required attention). The measurement upgrade addressed issues affecting key meter performance such as flow profile effects and valve noise with respect to ultrasonic measurement. A major factor in the success of the project was the use of a Measurement Exposure Model (MEM) which determined the measurement uncertainties associated with key metering points, and the impact they had on the final LNG Product Allocation. By using the MEM to focus on the effect of these measurement uncertainties, unnecessary modifications/upgrades were avoided and savings made in the overall project.