Effect of associated gas utilization on the creep life of gas turbines employed for power generation application

Abstract

Utilizing associated gas (A-Gas) in gas turbines for power generation applications would greatly solve some of the acute power challenges Nigeria is faced with over the years. However, utilizing A-Gas to generate a given power demand, would necessitate the engine fired with associated gas to consume more fuel; thereby causing the engine to operate at elevated turbine entry temperatures, which may affect the creep life of the turbines. This study investigates the effect of associated gas utilization on the creep life of gas turbines. GasTurb details 5.1 was employed to model the A-Gas fuel, while GasTurb 11 was used to model and simulate the performance of the aero-derivative gas turbine engine fired with natural gas and associated gas separately. The input and output gas path parameters obtained from GasTurb simulations which include mass flow rate, Pressure ratio, turbine entry temperature, engine rotational speed, power output etc. were used as input to size the HP turbine Blade. Larson Miller parameter and blade metal temperatures obtained for different sections of the blade were used to estimate the time to failure of the HP turbine blade for the two conditions (blade of engine fired with natural gas and A-gas separately) investigated. The results show that the estimated time to failure of the HP turbine blades for engine fired with natural gas is 49,821.4 h as against 33,158 h for the one operated with A-Gas fuel.