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[che22m]

Please share your ideas on how to improve LPG accounting.

Abnormal gains/losses in LPG imports are incurred in our refinery. The bill of lading and the actual shore receipt would differ up to more than 0.5% (basing on kL@15°C) which is our set allowable limit. To account for the shore receipt, manual measurements in the receiving spheres are taken. Data from sphere are: liquid height, sphere temperature, and system pressure. The corresponding liquid and vapor LPG are then computed and compared to the figure in the bill of lading.

Initial findings suggest that these abnormal gains/losses were incurred because sphere measurements were taken during non-equilibrium stage (of the LPG inside the sphere). This conclusion is supported by the significant positive/negative variances between the system pressure and vapor pressure at the time when the measurements were taken. Moreover, as per actual survey, liquid height continued to rise/fall with time. Also, changes in the temperature and system pressure (although relatively small) were observed.

However, allowing sufficient time for the system to reach equilibrium would increase demurrage costs and is therefore not considered an option. In addition, the sphere can be affected by sudden changes in the environment due to absence of insulation. Hence, equilibrium state may be impossible to attain.

We are planning to use Coriolis Flow Meters, which could directly measure mass flow rate, in the future. However, until that time comes, we still have to deal with abnormal gains/losses in LPG imports. I would greatly appreciate all your comments. Thank you very much for even reading this.

Regards.