Graph-based network modeling and simulation of condensers in once-through cooling water system under the effect of biofouling formation

Abstract This paper presents the modeling and simulation of a once-through steam condenser system dominated by biofouling in order to describe the behavior of an entire cooling system in power plants. A biofilm deposition model was fitted with experimental data and expanded in order to consider the effect of the temperature and substrate concentration. The proposed model is able to describe the behavior of the system during a fixed operation horizon where the effects of the temperature and water quality are associated to a biofouling rate model. The modeling employs a graph-based network approach to include in the analysis the pump water supply, the associated pipes, and the steam condenser itself. The fouling analysis encompasses thermal and hydraulic effects, i.e. the model can describe the impact of the fouling layer in the reduction of the overall heat transfer coefficient, but also in the increase in the flow resistance associated to the reduction of the free flow area and the increase of surface roughness. The importance of adopting the proposed model is demonstrated by the analysis of two different scenarios: a short-term simulation corresponding to the beginning of an operational run and a long term simulation of two years of operation.