Investigation of a Radial Turbine Design for a Utility-Scale Supercritical CO2 Power Cycle

Tala El Samad,Joao Amaral Teixeira,John Oakey

doi:10.3390/app10124168

Abstract

This paper presents the design procedure and analysis of a radial turbine design for a mid-scale supercritical CO 2 power cycle. Firstly, thermodynamic analysis of a mid-range utility-scale cycle, similar to that proposed by NET Power, is established while lowering the turbine inlet temperature to 900 ∘ C in order to remove cooling complexities within the radial turbine passages. The cycle conditions are then considered for the design of a 100 MW t h power scale turbine by using lower and higher fidelity methods. A 510 mm diameter radial turbine, running at 21,409 rpm, capable of operating within a 5% range of the required cycle conditions, is designed and presented. Results from computational fluid dynamics simulations indicate the loss mechanisms responsible for the low-end value of the turbine total-to-total efficiency which is 69.87%. Those include shock losses at stator outlet, incidence losses at rotor inlet, and various mixing zones within the passage. Mechanical stress calculations show that the current blade design flow path of the rotor experiences tolerable stress values, however a more detailed re-visitation of disc design is necessitated to ensure an adequate safety margin for given materials. A discussion of the enabling technologies needed for the adoption of a mid-size radial turbine is given based on current advancements in seals, bearings, and materials for supercritical CO 2 cycles.

Highlights

In compliance with the warnings of the Intergovernmental Panel on Climate Change [1] to limitCO2 discharges and keep the global temperature rise below 1.5 ◦ C, techniques for mitigating power generation emissions are being widely investigated; examples range from using non-conventional working fluids and increasing the efficiency of power plants to implementing carbon capture and storage (CCS) [2]
Suggestions from literature limit the applicability of radial turbines to cycles of up to
The criteria for that power level was proposed on the basis of closed supercritical CO2 (sCO2) cycles with lower operating pressures and temperature compared to conditions witnessed in cycles similar to the

Summary

Introduction

In compliance with the warnings of the Intergovernmental Panel on Climate Change [1] to limitCO2 discharges and keep the global temperature rise below 1.5 ◦ C, techniques for mitigating power generation emissions are being widely investigated; examples range from using non-conventional working fluids and increasing the efficiency of power plants to implementing carbon capture and storage (CCS) [2]. Oxy-combustion appears to be the most favourable CCS route because of the simple separation of carbon dioxide from the steam present in the flue gases [3]. The basis of this method is that a fuel is combusted with pure oxygen to produce a stream of exhaust gases consisting mainly of. With respect to unconventional working fluids, supercritical CO2 (sCO2 ) cycles are attracting growing interest due to the advantages associated with the fluid. The attractiveness of the use of sCO2 fluid is based on its availability and inertness as well as the consistently cited advantages of such power cycles [5]: .

Methods

Results

Discussion

Conclusion