The CFD Modeling of Heat Recovery Steam Generator Inlet Duct

The axial velocity and temperature distributions at the outlet section of inlet diffuser of Heat Recovery Steam Generator (HRSG) channel should be uniform as much as possible to avoid overheating of first rows of boiler heat exchangers tubes. Due to flow properties and angle of inlet diffuser, providing a uniform outlet velocity profile is impossible without using a correction device. A proposed design should be checked to satisfy the outlet velocity and temperature requirements. In current study, the abilities of computational fluid dynamics have been assessed to obtain the crucial profiles without the experimental difficulties. Regarding the special characteristics of flow and geometry, numerical solution may not be performed without taking some techniques into the CFD modeling. The actual HRSG inlet channel incorporates one perforated plate to correct the flow and three burner elements inside its wide-angle diffuser. Investigations have shown that the perforated plate and heat exchanger modules can be modeled by porous jump boundary condition and the burner elements by radiator faces respectively. Realizable k-e with non-equilibrium wall function seems to be the most optimum turbulence model for solution of the problem. KeywordsHRSG; Inlet Duct; Flow Correction; Diffuser; CFD