Modelling, simulating and optimizing boiler heating surfaces and evaporator circuits

A model for optimizing the dynamic performance of boiler have been developed. Design variables related to the size of the boiler and its dynamic performance have been dened. The object function to be optimized takes the weight of the boiler and its dynamic capability into account. As constraints for the optimization a dynamic model for the boiler is applied. Furthermore a function for the value of the dynamic performance is included in the model. The dynamic models for simulating boiler performance consists of a model for the ue gas side, a model for the evaporator circuit and a model for the drum. The dynamic model has been developed for the purpose of determining boiler material temperatures and heat transfer from the ue gas side to the water-/steam side in order to simulate the circulation in the evaporator circuit and hereby the water level uctuations in the drum. The dynamic model has been developed as a Differential-Algebraic-Equation system (DAE) and MATLAB has been applied for the integration of the models. In generalMATLAB has proved to be very stable for these DAE systems. Experimental verication has been carried out at a full scale plant equipped with instrumentation to verify heat transfer, circulation in the evaporator circuit and water level uctuations in the drum.