発電用大型ガスタービン冷却空気流量のヒータ法による計測

抄録

In large gas turbines, the cooling air flow rate is an important parameter for analyzing the temperature and efficiency of the stators and the blades, so measurement is desired. However, ultrasonic flowmeters are difficult to use because the temperature of the measuring section usually exceeds 300°C, while insertion-type flowmeters are difficult to apply because they require modifications to the piping for installation and cause a pressure drop. In this study, an attempt was made to apply the heater method to the measurement of cooling flow rates. In this method, an annular heater is attached to the outside of the pipe and the temperature distribution along the pipe axis is measured using thermocouples. The temperature distribution is affected by the flow velocity of the fluid in the pipe. The flow velocity can therefore be analyzed from the temperature distribution in the pipe. Measurements were conducted for two kinds of cooling air pipe at an advanced combined cycle power plant. In one, cooling air is extracted from the 13th stage of a compressor and supplied to the 2nd stators of the gas turbine; in the other, cooling air is extracted from the 9th stage of the compressor and supplied to the 3rd stators of the gas turbine. As a result, it was clarified that the cooling air flowrate had a positive dependence on atmospheric temperature at the plant. The dependence was also compared to that of a tit 1,600 degrees centigrade-class combined cycle power plant, with a power output of 700 MW.