An integrated theoretical fouling model for convective heating surfaces in coal-fired boilers

Particulate fouling on convective heating surfaces in coal-fired power plant boilers could lead to significant efficiency deterioration and frequent unit outages. In this paper, a new integrated particulate fouling model is presented by considering the combined suspended particles deposition and the fouling removal processes. A pre-deposited medium, rather than the tube wall, is taken as the target surface, while considering its internal microstructure, surface morphology and mechanical properties. To understand the processes of particle deposition and removal in inertial impaction, three fouling criteria are proposed in this paper by defining critical sticking angle and critical velocities. Some influential parameters, such as the interfacial adhesion energy and the fouling porosity, were studied, which revealed good prediction precision of the fouling model. Based on the fouling model presented in this paper, a computation fluid dynamics simulation was implemented to reconstruct the distribution of particulate fouling and the characteristic of fouling growth on economizer tubes.