Analysis and improvement of gas flow behaviour at the inlet duct of an industrial HRSG boiler through CFD modelling

Abstract

This work analyses and improves the distribution of the flow of flue gases along the inlet duct of two industrial Heat Recovery Steam Generation (HRSG) boilers. The inlet duct connection with the boiler casing presents a special configuration, being axial for one boiler and radial for the other. The study was carried out using a 3D Computational Fluid Dynamics (CFD) modelling. The flow uniformity improvement is studied considering the introduction of baffles, perforated plates and the Part Elimination and Lattice Search (PELS) method. The Root Mean Square (RMS) axial velocity is used to determine uniform flow distribution. Its value must be equal to or below 0.2 m/s. Nevertheless, the pressure drop in the boiler must not increase by 1 mbar as compared to the standard case. After analysing the 3D CFD modelling results, our conclusion is that, in an axial configuration, the PELS method and a perforated plate (TAD44A65) located at the inlet of the recovery zone can improve the fluid flow uniformity to 40 %. For the radial configuration, only a perforated plate (TAD44A65) located at the inlet of the recovery zone improves fluid flow uniformity to 43 %.

Keywords

• HRSG boiler
• Flow uniformity
• CFD
• Flow correction devices
• Combined cycle