3 Performance and Mechanical Equipment Standards

Combined cycle power plants and cogeneration plants all over the world require detailed specifications both from a performance as well as a mechanical point of view. The first decision is what type of combined cycle power plant should be built. Combined cycle plants are generally configured with each gas turbine and steam turbine driving a separate electrical generator. Since the two generators are on separate shafts, this configuration is called a multi-shaft combined cycle power plant. The term single-shaft combined cycle power plant refers to a configuration in which the gas turbine and steam turbine drive a single, common generator, with the various rotors connected by couplings to form a single shaft. These types of turbines are getting very popular in large plants around the world. The single-shaft combined cycle can be arranged in one of two ways: without a clutch or with a clutch.

The first step in designing a cogeneration or combined cycle power plant is the determination of the customers' requirements. Table 3-1 is a typical cogeneration questionnaire, and Table 3-2 is a typical questionnaire for the independent power industry, which should be answered so that a preliminary analysis can be made.