On the Performance and Operability of GE’s Dry Low NO_x Combustors utilizing Exhaust Gas Recirculation for Post-Combustion Carbon Capture

摘要

The capture and sequestration of CO_2 will be necessary to mitigate CO_2 emissions from fossil fuel (coal, oil, natural gas or biomass) power generation facilities in a carbon constrained world. Post combustion carbon capture is a viable technology alternative to reduce CO_2 emissions from power plants in the short term. The CO_2 concentration in the exhaust gases of natural fired power plants can be increased through exhaust gas recirculation (EGR). A joint CO_2 Capture Project (CCP) and GE study of the Best Integrated Technology (BIT) shows that EGR enables reduced exhaust gas flow to the post combustion capture plant and cost of the CO_2 capture. This paper describes the experimental work performed at General Electric Global Research Center in order to better understand the risks of utilizing EGR in combination with dry low NOx (DLN) combustors. A research combustor was developed for exploring the dry low emissions capability of nozzles to operate in low O2 environment. A series of experiments have been conducted at representative gas turbine pressures and temperatures, in an EGR test rig. Exhaust gas generated in a first stage, at pressure, is used to vitiate the fresh air to levels determined by cycle models. Experimental results include the effect of applying EGR on operability, efficiency and emissions performance under conditions of up to 30% EGR (low oxygen). Our findings confirm the feasibility of EGR for enhanced CO_2 capture, exceeding the expectations of operability and combustion efficiency predicted by models. In addition, we confirm benefits of NOx reduction while complying with CO emissions in Dry Low NOx Emissions combustors under low oxygen content oxidizer.