Steam Turbines

Abstract Energy conversion from thermal form (heat) to mechanical form (force or torque) are generally done through the fluid medium of either water/steam or air/gas. Cogeneration and combined‐cycles plants have become more popular in recent years due to their higher overall plant efficiency. Most turbines are designed at the high‐power condition (but not the maximum power) and are required to operate at a constant speed for some variation of output power. In a combined‐cycle power plant, the hot gas exhausted from a shaft power gas turbine is used to generate steam to drive a steam turbine. It can generally be designed such that the required equipment can be selected from the existing models (including gas turbine, steam turbine, and heat recovery steam generator (HRSG)). For the steam turbine driving an electric generator, the shaft rotating speed has to be constant in order to generate electrical output of constant frequency.