A CFD study by means of Fluent® software is presented. Aim of the fluid-dynamics analysis is the optimization of the air supply ducts of a steam generator, which is under construction in Abu Qir, Egypt, by Ansaldo Caldaie SpA. The steam generator has a capacity of 660 MWel and can be fed by fuel oil or by natural gas.
The CFD study covered the area from the FD fan to the air foils inlet, upstream of the air boxes. The study modeled the effect of the presence of two exchangers (aerotermo steamair and rotary Ljungström exchanger, which are in charge of the air pre-heating) onto the flow field and onto the thermal field in the ducts. By means of User Defined Functions, the real velocity profile induced by the fan was considered as boundary condition at the inlet of the computational domain.
The results highlighted the criticality of the studied geometry: the initial configuration induced velocity nonuniformity at the exchangers entrance, flow separation and massive recirculation, thus increase of the pressure drop beyond the project expected values, which had been estimated by a one-dimensional analysis.
Then a new configuration was designed, by including suitable conveyors, which improved the fluid dynamics of the ducts, in terms of pressure drop and performance. |
22-23 October 2012 Pacengo del Garda 
