Bioethanol Combustion in an Industrial Gas Turbine Combustor: Simulations and Experiments

Abstract

Combustion tests with bioethanol and diesel as a reference have been performed in OPRA's 2 MWe class OP 16 gas turbine combustor. The main purposes of this work are to investigate the combustion quality of ethanol with respect to diesel and to validate the developed CFD model for ethanol spray combustion. The experimental investigation has been conducted in a modified OP 16 gas turbine combustor, which is a reverse-flow tubular combustor of the diffusion type. Bioethanol and diesel burning experiments have been performed at atmospheric pressure with a thermal input ranging from 29 to 59 kW. Exhaust gas temperature and emissions (CO, CO2, O2, NOx) were measured at various fuel flow rates while keeping the airflow rate and air temperature constant. In addition, the temperature proflle of the combustor liner has been determined by applying thermochromic paint. CFD simulations have been performed with ethanol for flve different operating conditions using ANSYS FLUENT. The simulations are based on a 3D RANS code. Fuel droplets representing the fuel spray are tracked throughout the domain while they interact with the gas phase. A liner temperature measurement has been used to account for heat transfer through the flame tube wall. Detailed combustion chemistry is included by using the steady laminar flamelet model. Comparison between diesel and bioethanol burning tests show similar CO emissions, but NO^ concentrations are lower for bioethanol. The CFD results for CO2 and O2 are in good agreement, proving the overall integrity of the model. NO^ concentrations were found to be in fair agreement, but the model failed to predict CO levels in the exhaust gas. Simulations of the fuel spray suggest that some liner wetting might have occurred. However, this finding could not be clearly conflrmed by the test data.

Transient heat transfer between a turbulent lean partially premixed flame in limit cycle oscillation and the walls of a can type combustor

“…The effect of radiative heat transfer is therefore neglected. The choice to neglect radiation is supported by [23]; Furthermore calculations of estimated emitted and absorbed thermal power of radiation confirm that radiation is a relatively insignificant phenomenon in the explored cases. This calculation is given in the appendix A.…”

The impact of spray quality on the combustion of a viscous biofuel in a micro gas turbine

“…While reciprocating engines are very sensitive to problems such as clogging and delayed ignition, gas turbines have shown good potential to cope with alternative fuels. Experimental studies have shown that most common biofuels, such as bioalcohols and biodiesel, can already be burned in pure form in standard or slightly modified combustor designs without any significant problems [4][5][6][7][8][9].…”

Experimental investigation of spray characteristics of kerosene and ethanol-blended kerosene using a gas turbine hybrid atomizer

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