Air Intake System Impact on Gas Turbine Performance

Abstract

Limitations of space and weight on offshore platforms have made gas turbines the main supplier of power in these installations. Particles escaping from the inlet air filtration systems cause fouling of the gas turbine compressor section and decrease the overall effciency of the engines. New focus on decreasing global environmental gas emissions has made the importance of optimal gas turbine operation increasingly important. This thesis documents gas turbine degradation mechanisms and evaluation of parameters for the detection of their impact on gas turbine performance. The impact of different economical parameters on gas turbine deterioration and expectations of their predicted future growth is presented. The deterioration rate of nine gas turbines with two different types of filtration systems were documented over representative time intervals from the year of 2009. Of these nine, three were of the model LM2500+ and six were of the model LM2500. One of the evaluated gas turbines has a daily online water wash routine. The calculated deterioration rates of this engine was found to be one third of the rate of the engine it was compared to. The finding is significant, although the gas turbines neither share the same type of filtration system nor elevation above sea level. By evaluation of documented deterioration rates and filter testing in the NTNU laboratory test rig, the filtration efficiency of filter type B was found to de- crease considerably during the time in operation. The deterioration rate in the evaluated time interval after the filter change showed a 35% decrease from the previous. Economical considerations are presented, and give a perspective on the achievable savings on environmental taxes, fuel consumption and the prevention of lost production due to decreased deterioration rates. Optimization of time between offline water wash is presented for the gas turbines on Facility X, and is calculated to be 397 hours versus the current practice of 2,000 hours.