Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Gas flow measurement under high pressure flowing conditions: Analysis of the uncertainty of the reported measurement at standard conditions
Submission Author:
Marina Mosckem , ES
Co-Authors:
Marcio Coelho, Rogerio Ramos, Marina Mosckem
Presenter: Marina Mosckem
doi://10.26678/ABCM.COBEM2017.COB17-1606
Abstract
It is common for regulations to require natural gas flow measurement to be reported on a volumetric basis. Therefore, the measurement should also be reported at a specific pressure and temperature, referred to as standard conditions. In Brazil, petroleum and gas measurements must comply with ANP/Inmetro Ordinance 01/2013, which states the following standard conditions: 1 bar, 20°C. When the flowing conditions are not the same as the standard ones, the measurement must be corrected for the standard condition by means of thermodynamic Equations of State – EOS. Thus, the measurement reported in the standard conditions carries a portion of uncertainty relative to this operation, whose value depends on the temperature and pressure, as well as on the chosen EOS. The main goal of the work is to evaluate this parcel of the uncertainty, especially in critical flowing conditions. Some typical natural gas compositions were selected and the following flowing conditions: 50 bar, 4°C. Results obtained by means of Monte Carlo simulation show that the measurement reported at the standard conditions carries a portion of uncertainty generally greater than 1.0 percentage points, only due to the necessary correction just commented. It is a significantly high value, especially if we take into account that Brazilian regulation states a maximum of 2% for fiscal measurements, for example.
Keywords
gas flow measurement, Measurement uncertainty, Monte-Carlo simulation, equation of state, flowing and standard conditions
