A PHYSICS-BASED DYNAMIC MODEL FOR BOILERS, PART 1: MODEL DEVELOPMENT AND VALIDATION

This paper is the first part of a two part study that develops, validates and integrates a one-dimensional, physics-based, dynamic boiler model suitable for application with model based control. Part 1 of this study extends and validates the existing, higher order modelling framework of Badmus et. al. [1] to boilers. This requires derivation of particular, one-dimensional forms of the equations for heat, mass and momentum transfer in single (liquid and gas) phase and two phase fluids with real fluid properties. The so-called 'forcing term' mapping functions in these equations only require knowledge of steady state system behaviour, and so can be obtained from steady state measurements throughout the boiler system. Additional models are also presented for other boiler components, including the steam drum in sub-critical boilers. The overall framework is then used to develop and validate a model of a GW scale, sub-critical boiler in an operating,. electrical power plant. Overall, the model achieves reasonable agreement with the power plant dynamics during normal transient operations, including acceptable tracking of the drum dynamics and the steam at the boiler outlet. As such, this modelling framework appears suitable for developing models of sufficient fidelity yet retain an appropriate form for model reduction using singular perturbation analysis techniques, as demonstrated in Part 2 [2] of this study.