DESIGN AND MODELING OF AN 80 BAR OXY-COMBUSTOR FOR DIRECT FIRED SUPERCRITICAL CO2 APPLICATIONS

Abstract

As supercritical CO₂ power cycles for fossil energy power generation continue to generate interest, there are significant issues and unanswered questions regarding injector design, flame stabilization, wall heat transfer, CO emissions, combustion dynamics, and other combustion phenomenon. For natural gas, direct-fired cycles with carbon capture it is believed that computational fluid dynamics (CFD) modeling will play an essential role in the combustor design process. To accurately model turbulent reacting flows at these unique conditions, experimental data are needed to validate CFD codes and sub-models and are currently lacking at conditions relevant for these cycles. This paper presents the conceptual design and CFD simulations of an experimental 80 bar oxy-combustion facility and test article currently under construction at National Energy Technology Laboratory (NETL). The facility is targeted towards the testing of a single-injector, direct-fired sCO₂ combustor at the 100 kW thermal output level. While these conditions do not reflect the actual Allam cycle operating conditions (300 bar) they are viewed as a stepping stone in the model validation process at supercritical conditions. Reynolds Averaged Navier-Stokes as well as Large-Eddy Simulation are used to model the turbulent combustion process and aid in the design of the combustor and injector. Process parameters including oxidizer preheat temperature and combustor flowrate are investigated.