Mathematical modeling, simulation and validation of a boiler drum: Some investigations

The boiler or steam generator is a widely-used energy conversion equipment across the industry to generate steam for power generation or utility purposes. Recently, there is an increasing demand to operate the thermal power plant boilers in more flexible and agile manner due to renewable energy penetration, excess generation capacity, online trading, etc. Mathematical models representing dynamic behavior of the power plant boilers across wide-range operational scenarios like start-ups and load-changes are necessary for such operability and control studies. However, boiler models suitable for such investigations are scarce in the literature. This paper presents a mixed standard lumped model representing the boiler-drum dynamics and a 1-dimensional distributed model based on two-phase thermal hydraulic stability code to represent dynamics of evaporator sub-system. The model is validated using wide-range operational plant data collected from a boiler unit of a combined cycle power plant. Besides, the performance of the proposed model is compared with other two well-known first-principle based models. The performance metrics used for comparisons are small range accuracy, wide-range accuracy, relative computational time and memory requirements. The proposed model is found to out-perform existing models, particularly for the wide-range dynamic operational scenario. •A first-principle mixed nonlinear mathematical model of the boiler is proposed.•A blend of lumped model of drum and 1-dimensional distributed model of evaporator.•Simulation results validated with diverse startup data from combined cycle boiler.•Investigated superiority of proposed model with two other nonlinear boiler models.•Results & metrics to choose modeling practice for boiler systems & controls domain.