A Short Introduction of Blade Cooling Mechanisms in Old Gas Turbines with the Aim of Proper Distribution of Temperature Profile

Abstract

Presently, old gas turbines are used in the industry of some developing countries without high tech, which face many problems in the field of thermal efficiency and output power. Typically, turbines operate in the temperature range of 1200 to 1500 degrees Celsius. Many studies have been done to increase the efficiency of such systems. The results show that this increase in temperature at the inlet of the gas turbine has negative consequences, such as increasing the thermal load of the turbine blades and thus reducing the lifetime of the blades. On the other hand, a damaged blade can cause serious damage to other blades as well as the main shaft and other parts in various ways and sometimes lead to complete failure of the turbine. Therefore, it is reasonable to consider cost reduction considerations, including maintenance. Hence, due to the limitation of thermal stresses for the continuous operation of gas turbine blades, the distribution of heat transferred to them must be controlled. In this regard, the presence of blade cooling mechanisms is necessary for its safe operation, because the operating temperature of the gas turbine is much higher than the allowable temperature of the blades. In addition to cooling the blades, cooling the shell and inlet nozzle of gas turbines is also extremely important. But since the blades are exposed to high-level stress and tension for a long time, their cooling is more important and sensitive. For this reason, in the present article, the authors tried to provide a short introduction to the efficient mechanisms in cooling the blades related to the old systems, whose effect is noticeable on increasing the lifetime of the blades.