Investigation of the Flow Pattern in a Complex Inlet Duct of a Heat Recovery Steam Generator

Abstract

Numerical simulation and experimental study were conducted in order to analyze flow patterns and finally to find out appropriate alternatives for uniform flow in the transition zone of the vertical type Heat Recovery Steam Generator (HRSG) for a gas turbine combined cycle. To understand flow patterns in the interconnecting duct between the gas turbine exhaust and the inlet of the HRSG, flow measurement was conducted in a 1/20 scale-down model. Velocities were measured by pitot tubes on selected sections and uniformity of the flow was quantitatively evaluated. Water table test was also carried out to visualize the flow and to compare the flow patterns according to the selection of alternative shape design of the transition zone, which would lead to better uniformity of the flow in the duct. Numerical simulation by a commercial Computational Fluid Dynamics (CFD) code was performed to augment the model tests and to consider various ideas for better uniformity. Finally, selected alternatives for the uniform flow chosen from the numerical study were checked against in experiments.