Model library
 |
The model library for the components of the steam cycle is shown in Fig. 2. This library consists of components for the steam turbine, pump, condensator, boiler, generator etc (Fig. 2). Also a library has been created for the hybridization components: a gas turbine and a burner as well as for the solar circle consisting of a heliostat field, a storage device and a receiver (Fig. 2).
Each component consists of input, output and parameter variables. For instance variables that are delivered from one component to the next are pressure, temperature, mass flow, enthalpy of the fluid. In addition, for certain components power or heat is a value that is used for calculation. The models are based on thermodynamic theory using assumptions to simplify the calculations. The assumptions are made in a way that the physical behaviour and a reasonable accuracy are maintained. The main reason for the simplification is to achieve a fast simulation for one year.
Steam Cycle
The main steam cycle components are the HRSG, the feed water pump, the steam turbine and the condenser. The HRSG consists of three stages the economiser, the evaporator and the superheater. Beneath the calculation of the generated saturated steam, the evaporator transmits the feed water demand to the pump by a signal. The last component of the boiler provides superheated steam for the turbine. The heat transfer is calculated with the input conditions of the hot air or exhaust gas by using the method of effectiveness of heat transfer. The turbine and the pump model using an inner efficiency to evaluate the output enthalpy and the power that is produced or consumed. Efficiencies can be set to a constant value or provided by a characteristic diagram. After the steam is expanded by the turbine it is condensed in the condenser. It is assumed that the water leaving the condenser is saturated. The conversation of energy and a constant temperature difference between the steam and the cooling water delivers the temperature rise of the cooling water.
