Effects of Operating Conditions on Gas Release Thermal Consequences: a case study of the Trans- Saharan Gas Pipeline

Abstract

A recent study concluded that militant activities/insurgency constitutes the biggest threat to the proposed Trans-Saharan Gas Pipeline (TSGP) intended to traverse Nigeria, Niger and Algeria. Hence gas release is a credible source of concern. Using the potential leak of inventory from the TSGP as a case study; this paper assesses the Simplex Source Term and Multivariate Consequence Modelling approaches. Aspen HYSYS® platform was used to determine the average Molecular Weight and Lower Heat of Combustion of the gas mixture. Thereafter, the gas discharge rates for various leak scenarios were evaluated. The gas release rates and the flame length of the potential jet fires were initially estimated using Simplex Source Term Models which pay limited attention to operating conditions. Finally a more detailed follow-up study, accounting for a range of practical factors was conducted. A number of useful risk management metrics were determined. For example, the release rate for the 100mm leak is about 130.50 kg/s and 162.13 kg/s for scenarios with and without modifiers respectively. Similarly, the maximum flame lengths were found to be significantly different with values of 8m and 142m with and without modifiers respectively. The results show that the direct approach could be overly conservative, hence more expensive to implement.