Part-Load Operation of a Piloted FLOX® Combustion System

Abstract

A large operational envelope is a key requirement for modern gas turbines. Fuel staging is used here to improve the part load performance of an enhanced FLOX® type combustor. A swirl-stabilized pilot stage is integrated in the FLOX® burner and the results of high pressure lab-scale experiments at system relevant conditions are presented. The operational envelope of the piloted system could be extended by approximately 10%. Pressure scaling and variations of air preheat temperature and jet velocity describe fundamental characteristics of the piloted system. OH* chemiluminescence imaging is used to investigate flame shapes and the effect of the interacting flames. Emissions and pressure pulsations define limits, and optimum operation conditions of the combustor and show the influence of part load relevant parameters.

A criterion to distinguish autoignition and propagation applied to a lifted methane–air jet flame

“…The design complexity of modern combustors is constantly increasing -for example in land-based gas turbine applications, sequential combustion or axial staging concepts [1][2][3] involving Moderate or Intense Low-oxygen Dilution (MILD) [4], or Exhaust Gas Recirculation (EGR) architectures [5]. These technology step-changes are driven by the demand for lower pollutant emissions, higher efficiency and higher fuel and operational flexibility.…”

High Momentum Jet Flames at Elevated Pressure: B — Detailed Investigation of Flame Stabilization With Simultaneous PIV and OH-LIF

“…High momentum jet stabilized combustion systems provide an interesting alternative for gas turbines, replacing state of the art swirl stabilized combustors. These high momentum jet combustion systems, also termed FLOX ® -combustors [1,2], have been shown to operate reliable, load-and fuel-flexible with low pollutant emissions in a wide range of gas turbine relevant conditions [3][4][5][6]. Note that the term FLOX ® (flameless oxidation) is used for historical reasons and only refers to the kind of combustor and not to the kind of combustion (which is typically not "flameless" at gas turbine conditions).…”

Confinement-Induced Instabilities in a Jet-Stabilized Gas Turbine Model Combustor

“…In recent years, a series of jet-stabilized combustors based on the FLOX concept have been developed at DLR and have been the subjects of extensive experimental [1][2][3][4][5][6][7][8] and numerical studies [9,10]. The concept is regarded as a viable alternative to swirl-stabilized flames due to its high resistance to thermoacoustics and flame flashback [1], while also attaining high fuel flexibility and low NOx production [2].…”

“…Without alluding to the flameless [11], volume or mild combustion [12], FLOX combustors refer exclusively to combustors designed following a core principle: flames are stabilized by intense mixing of the reactants and products from strong flow recirculations created by high momentum jet(s) discharged into the combustor chamber. A series of combustors with various nozzle configurations have so far been tested (at either room or elevated pressures): (1) combustors operate with (partially) premixed air and gaseous fuels (mainly methane and hydrogen), and features either a single nozzle [3], linearly aligned multiple nozzles [5] or circularly arranged multiple nozzles with [4] and without a pilot flame [1,2,8]; (2) combustors operate with liquid fuels and incorporate either a single nozzle or multiple nozzles [6]. In particular, the single-nozzle FLOX combustor developed in Ref.…”

“…It was offset from the geometric center of the combustor chamber, creating an asymmetry in the front view ( Fig.1(b)). The off-center positioning of the jet was designed to imitate the situation around a single nozzle in a multi-nozzle FLOX combustor, where nozzles were commonly placed near the chamber wall, leading to the formation of a large recirculation zone to one side of the jets [2,4,5]. The combustor was mounted on a three-axis translation stage and could be positioned with regard to the diagnostics setup.…”