Dynamic simulation of heat recovery boilers by using the sequential modular technique

摘要

As an introduction to this work the energy and power situation in Norway is described, and objectives and motivations for dynamic simulation of thermal power plants are highlighted. Also, the concepts of modeling and simulation are introduced. The dynamic characteristics of heat recovery boilers are outlined. Dynamic models for components in a heat recovery boiler is deductively developed by using conservation principles for mass, energy and momentum as a starting point. The rigorous models form complex equation systems. Therefore, knowledge about the dynamic characteristics of the system is used as a background for the simplifications and the development of final dynamic models of the boiler components (modules). The modules developed in this work are able to predict the behavior in the low frequency range: slow, thermal variations, load changes and start-ups. Independent modular simulation allow the modules to integrate independently. This is in contrast to modular equation oriented simulation where the total system is integrated by a common integrator. The concept of independent modules reduces model complexity considerably, and it is, therefore, specially attractive for start-up analysis, which until now has been a complicated task. Special aspects about the method; choice of information flow between modules, discontinuities, and algebraic loops, are paid special attention to in this thesis. To validate the models, test-data from a start-up of a 35 MW single-pressure boiler was provided by the company SIEMENS. A comparison with the measured data gives satisfactory results. 59 refs., 60 figs., 10 tabs.