EXPERIMENTAL INVESTIGATION OF THE COMBUSTION CHARACTERISTICS OF A DOUBLE-STAGED FLOX~® -BASED COMBUSTOR ON AN ATMOSPHERIC AND A MICRO GAS TURBINE TEST RIG

摘要

To establish micro gas turbine (MGT) systems in a wide field of CHP applications, innovative combustion concepts are needed to meet the demands for low exhaust gas emissions, high efficiency and reliability as well as high fuel flexibility. A promising technology for future MGT combustion is the FLOX~® concept. The goal of the presented work is to prove the feasibility of a double-staged, FLOX~®-based MGT combustion system on a MGT test rig. The paper reports a reliable operating behavior of a Turbec TWO MGT in combination with the new FLOX~®-based combustion chamber utilizing natural gas. The measured exhaust gas emissions are compared for different configurations of the combustion chamber and the standard Turbec system. It is shown that the carbon monoxide emissions are reduced whereas the nitrogen oxide emissions exceed the emission levels of the standard MGT burner. However, they still fall far below the German legal limits. For helping to interpret the results of the MGT combustion system, the double-staged combustor is compared to a single-staged FLOX~® burner on basis of atmospheric measurements. Here, it is shown that the margin to lean blow-off is substantially increased by the fuel staging. Moreover, it is demonstrated that the exhaust gas emissions of the double-staged combustor could be kept at a similar very low level by applying the staging. Additionally, the overall reaction regions are reported by OH~* chemiluminescence imaging as a function of burner air number. Based on this atmospheric study the transfer to MGT conditions is made and appropriate measures are derived to optimize the exhaust gas emissions of the MGT FLOX~® combustion system.