Design of the steam turbine for small scale power plant

Abstract

The aim of this study is to design a steam turbine for a small scale steam power plant and industrializes the design, the turbine driven by the energy of coconut shells; a renewable energy source with lower cost, as the source of energy. The study was concentrated on steam cycle, type of turbine, requirements of a perfect output power of the turbine, design and operation, turbine rating, elements of the turbine and steam condition. In addition analysis was done on on-going small scale power plane projects in Sri Lanka. In this Impulse turbine design we consider steam turbine blade stress failure (tensile and bending stress partly) due to the centrifugal force as a result of high rotational speeds and partly due to high pressure, temperature and speed steam loading. And we consider the blade efficiency and the angle for blade design parameter. The steam cycle was designed according to the available data and the turbine calculations were done by using trial and error method using ASME turbine design manual, Solid work and the software ANSYS. Over view of the project design is: Available power of the plant 100kW, isentropic efficiency 80 , Cycle power output 115kW, Turbine output 122.5kW, Gear efficiency 90%, Generator efficiency 90%, generator speed 3000rpm, turbine blade length 200mm, blade radius 300mm, Nozzle diameter 3.15mm, maximum angle of nozzle 63.09˚, shaft length 240mm, Shaft diameter 40mm,shaft speed 3000rpm,rated load 680N, Inlet Flow rate 0.144 kg/s, Cycle efficiency 25.2 ,Overall efficiency 19 , Water tube boiler Efficiency 80%, Inlet pressure 30 bar, Design pressure 32.4 bar, Overall heat transfer coefficient 235.06 W/m²°C.