ASSESSMENT OF GAS TURBINE'S COOLING SYSTEMS INTEGRATED WITH BOTTOMING CYCLE

摘要

With the everlasting increase in the population, a huge surge in the electricity consumption can be noticed. Thus, the power and electricity generating power plants need to augment their performance to cope with this uprising problem. The main goal for most gas turbine power plants is to increase their efficiency and performance which can be achieved by increasing the turbine inlet temperature (TIT). However, increasing the TIT requires cooling of the turbine blades to extend its lifetime and avoid thermal stresses and oxidation rates. Usually, there are two routes to improve the turbine blade cooling, either scientist focus on the parameters that effect the cooling process such as the film cooling effectiveness, shape of holes and angle of injection, or the problem is approached from a thermodynamic point of view. It is well known that the air used to cool the turbine blades is bled from the compressor which causes a severe penalty on the thermodynamic efficiency and power output of the gas turbine. This paper main objective is to improve the gas turbine performance by lowering the temperature of the coolant lines bled from the compressor for turbine blade cooling resulting in a reduction in the amount of coolant mass flow rate required for turbine cooling which will reduce the penalty on the overall efficiency increasing it. For this purpose, three different configurations of Maisotsenko desiccant cooling systems were proposed to cool down coolant lines as well as the inlet air temperature. Optimization analysis was performed to determine the best operating parameters of the gas turbine as well as the cooling systems. Sensitivity analysis was conducted as well to investigate the effect of various variables on the gas turbine overall efficiency and the coolant mass flow rate. The results showed an increase in the overall efficiency from 42.57% to 43.83%, reduction in the amount of coolant mass flow rate that is bled from the compressor from 4.584 kg/s to 3.607 kg/s and in the cooling fraction from 4.72% to 3.9%.