Following the trends of integrating intermittent renewable energy into the electrical grids, design processes and tools for thermal power plants are changing. Utility-scale boilers are complex thermodynamic systems, which consist of components like combustors, heat exchangers, pumps, or valves. These components are well understood in principle and can be described with fundamental physical equations such as mass, energy, and species balances as well as heat transfer, and pressure loss correlations. Evolving computational performance and transient system simulation tools allow the coupling of these components and the creation of system models which support the design process to adapt to the energy market trends.
The paper will give insights into the underlying modelling approaches and assumptions for a commercial, 540MW boiler design process. System model validation for a wide load range will be shown based on plant measurement data. The paper will cover the implementation of an innovative dual-fuel combustion model, which allows switching from 100% coal operation to 100% natural gas operation. In addition, ramp-rate studies will be presented, affecting critical operational data such as temperature differences in critical headers causing thermal stress. The presented approach serves plant designers, owners, and operators to increase safety, reduce commissioning times and maximize output.