EXECUTIVE SUMMARY

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EXECUTIVE SUMMARY

The present thesis reports about the field of the co-firing technique applied on existing coal-fired power plants. In particular, it focuses on the variations that co-firing retrofit has on boiler performances.

The work, held at KEMA Nederland B.V., had the goal to develop a new version of an existing model for the simulation of boilers, used to predict the effect of co-firing on their thermodynamic performances. The new model is meant to replace the one actually employed by KEMA that, despite being accurate and reliable, requires a relatively long execution time.

Initially, with the aim to define the co-firing technique, the state-of-art and the main challenges, associated with the simultaneous combustion of coal and biomass, have been analyzed. Successively, the work focused on the realization of a new boiler model, starting from the existing version, based on a novel conceptual approach. The predicting methods of the new model presents a faster computational structure, based on the effectiveness method, that accounts for the effects that the flue gas properties have on radiative and convective heat transfer phenomena.

The new model was finally validated by comparing its predictions from some simulations of a 1600 MW

pulverized coal-fired boiler, with the predictions given by the existing model, under the same operative conditions.

The comparison has confirmed the correct approach used for the new model. The new

version is able to predict boilers performances with an accuracy close to the model used

by KEMA, reducing, at the same time, the computational effort sensibly.