Exhaust Gas Recirculation Performance in Dry Low Emissions Combustors

Abstract

In a carbon constrained world there is a need for capturing and sequestering CO2. Post-combustion carbon capture via Exhaust Gas Recirculation (EGR) is considered a feasible means of reducing emission of CO2 from power plants. Exhaust Gas Recirculation is an enabling technology for increasing the CO2 concentration within the gas turbine cycle and allow the decrease of the size of the separation plant, which in turn will enable a significant reduction in CO2 capture cost. This paper describes the experimental work performed to better understand the risks of utilizing EGR in combustors employing dry low emissions (DLE) technologies. A rig was built for exploring the capability of premixers to operate in low O2 environment, and a series of experiments in a visually accessible test rig was performed at representative aeroderivative gas turbine pressures and temperatures. Experimental results include the effect of applying EGR on operability, efficiency and emissions performance under conditions of up to 40% EGR. Findings confirm the viability of EGR for enhanced CO2 capture; In addition, we confirm benefits of NOx reduction while complying with CO emissions in DLE combustors under low oxygen content oxidizer.

Effect of Change in Fuel Compositions and Heating Value on Ignition and Performance for Siemens SGT-400 Dry Low Emission Combustion System

“…The benefit of NOx reduction by using normal MCV fuels was widely reported [1,[9][10][11][12][13][14], for example; 20% reduction with 35% N2 in the fuel [1], 40% reduction with 50% N2 in the fuel [2] and about 50% reduction with 35% CO2 in the fuel [6]. NO^ is also sensitive to the selection of diluents, generally more NOx is produced if N2 is selected as diluent [7,9].…”

“…Another factor may be due to a change in chemical reaction by adding CO2 or N2 in the reactant. Also with the presence of CO2 and/or N2 in the fuel, the reactant becomes less active due to the reduction of oxygen concentration in the reactant [11]. This suppression effectively reduces the size of the O/H/OH radical pool [22] and suppresses the formation of NOx.…”

Feasibility of Selective Exhaust Gas Recycle Process for Membrane-based CO2 Capture from Natural Gas Combined Cycles – Showstoppers and Alternative Process Configurations

“…CO 2 , H 2 O)  Increase in concentration of gases with kinetic activity (e.g. CO 2 ) limiting full oxidation of intermediate species  Decrease in temperature  Increase in pressure Experiments performed in laboratory conditions for conventional EGR (3-5 vol% CO 2 in combustor inlet gas) indicate that 16% O 2 concentration is a limit to ensure complete combustion and limit CO emissions [6][7][8][9]. However, no experimental data is available for S-EGR conditions where CO 2 concentration in the combustion inlet gas is around 9-18 vol% depending on the process design and membrane performance.…”

Effect of Change in Fuel Compositions and Heating Value on Ignition and Performance for Siemens SGT-400 Dry Low Emission Combustion System

“…The benefit of NOx reduction by using normal MCV fuels was widely reported [1,[9][10][11][12][13][14], for example: 20% reduction with 35% N 2 in the fuel [1], 40% reduction with 50% N 2 in the fuel [2] and about 50% reduction with 35% CO 2 in the fuel [6]. NOx is also sensitive to the selection of diluents, generally more NOx is produced if N 2 is selected as diluent [7,9].…”

“…This suppression effectively reduces the size of the O/H/OH radical pool [22] and suppresses the formation of NOx. Also with the presence of CO 2 and/or N 2 in the fuel, the reactant becomes less active due to the reduction of oxygen concentration in the reactant [11]. For industrial lean premixed system the unmixedness is a factor that can affect NOx.…”