Research On The Calculation And Dynamic Character Of A Simulation Model For The Multi-pressure Heat Recovery Steam Generator

The dynamic character of the heat recovery steam generator is important in analyzing dynamic character of an advanced combined cycle. The dynamic character of steam temperature for the multi-pressure heat recovery steam generator is studied in this thesis.First, the dynamic mathematical models for the typical components of the heat recovery steam generator are built up on the basis of fundamental physical laws, which are composed of the single-phase region models(economizer,superheater and reheater) and evaporating zone model. The mathematical models of the typical components are established by the lumped-parameter approach. In the single-phase region the medial parameter is regarded as the characteristic parameter, in order to avoid "See-Saw", we can suppose that the derivative of medial parameter is equal to that of export parameter. Because the temperature and enthalpy of the fluid have the character of impressing one direction, while the pressure and flux have the character of impressing two directions, steam-water system can be divided into pressure-flux channel and enthalpy-temperature channel. We don't adopt the traditional method which regards the evaporating zone as one section to establish mathematical model, here, it will be divided into five sections.Second, sequential modular approach is applied to establish the dynamic mathematical model describing the connections of each model for the whole system of the heat recovery steam generator, how to use sequential modular approach to study the dynamic character of the heat recovery steam generator is great in this thesis. In the secondary modeling, "Hidden Euler" approach is applied to solve the nonlinear simultaneous differential equations, and the discrete nonlinear algebraic equations are calculated by "Newton-Raphson" numerical approach. Dynamic characteristic of a heat recovery steam generator is simulated and the result of simulation is analyzed as well. So applying sequential modular approach to study the dynamic character of the heat recovery steam generator is sound. Finally, sequential modular approach is applied to establish the dynamic mathematical model for the multi-pressure heat recovery steam generator in visual simulation environment. With the correlative models, we can simulate for the advanced combined cycle.