Performance assessments and simulations of ROT (radial outflow turbine) for back-pressure turbine generator system

Abstract

The high pressure steam is regulated by the Pressure-Reducing Valves (PRVs) to suit the various industrial process; however, this, inevitably leads to economic and energy losses. In this study, PRV is replaced by a back-pressure turbine generator comprising a Radial Outflow Turbine (ROT). The structural characteristics of the ROT, such as the easy adjustment of the tip clearance, make it possible to control the steam properties. The steam with selectively reduced pressure (and temperature) can be provided to users. The blade geometry of the ROT is designed using a commercial software. The numerical prediction of the fluid properties is carried out using a real fluid model in ANSYS-CFX. The simulation results are compared with the experimental results obtained under the same off-design conditions. The tip clearance (100, 300 and 500 mu m) are applied as a parameter to investigate the change of performance and to adjust the properties of the discharged steam. The experimental results show that the maximum electrical power produced at the minimum tip clearance is 12.8 kW, and the temperature and pressure differences tend to decrease with increasing tip clearance. These results demonstrate the potential of the ROT as a PRV and energy recovery device in back-pressure turbines. (C) 2021 Elsevier Ltd. All rights reserved.