The demand for rapid changes in power generation is increasing and thus leading to a requirement for the quick start of the boiler from the cold state. However, one has to be careful to not heat it too rapidly, as it might lead to material failures. This example uses a moderately complex nonlinear boiler model that captures the key dynamical properties.
The nonlinear drum boiler model has three control inputs: feedwater flow rate, heat input and position of a valve at the steam outlet. The feedwater needs to be controlled so that the water level inside the drum is kept at its set point. A PI control loop is added for this purpose.
Complete drum boiler model, including evaporator and supplementary components.
Analyze Thermal Stresses
In the following plot, you can observe that as the startup time is shortened, the thermal stresses operating on the boiler walls increase. The gray-dashed curves are not within the tolerable thermal stress limits. For this model, a startup time of about 3000 seconds is required for safe operation.
Use the Wolfram Language to carry out parametric analysis.
The magnitude of the thermal stress should be below 10 for safe operation.