Combined cycle power plant utilising pressurised fluidised bed coal combustors (PFBCs) have, of necessity, to be designed to suit the particular gas turbine chosen. The gas turbine characteristics set not only the design point but also the turndown available. The interactions between the gas cycle, the combustor and the steam cycle are different to those normally associated with combined cycle plant.
This paper describes the methods available when designing for plant operation at off-design conditions. It is shown how available techniques are capable of meeting commercial plant requirements for start-up, rates of load change and turndown.
