Experimental and Numerical Investigation of Ultra-Wet Methane Combustion Technique for Power Generation

Abstract

Using steam as heat carrier and working media has merits to increase electric efficiency up to 60% and decrease NOx emission to single-digit compared to dry gas turbine cycles. These attribute to the physical properties of steam as having high heat capacity to reduce local flame temperature, and hence reduce emissions by inhibiting thermal NOx forward reaction rate. In this work, ultra-high steam content with steam-to-air mass ratio up to 40% is premixed with methane air mixture before entering a swirl-stabilized HP-burner for combustion. Significant change of flame from V-shape (attached) to M shape (detached) is observed through a transparent combustion chamber. The measurement of chemiluminescence OH* is conducted with an intensified CCD-camera band-pass filtered at 320nm. Large eddy simulation is used to capture reacting flow features. Reasonably well agreements between experimental data and numerical results are obtained for both attached and detached flames in terms of OH* distribution. Distributed flame front is clearly identified with LES for wet methane combustion associated with 35% steam-to-air ratio corresponding to a high Karlovitz number flame. Slightly unstable combustion is observed when steam-to-air ratio exceeds 40% featuring an onset of flame blow-off. Interaction between precessing vortex core and the flame is presented at different level of steam dilution, and conclusions are drawn regarding flame stabilization. The in-depth understanding of ultra-wet combustion is an important step towards the use of sustainable, steam-diluted bio-syngas for electricity production.

Characterization of Distributed Combustion of Reformed Methanol Blends in a Model Gas Turbine Combustor

“…It is worth pointing out that this burner configuration has previously been studied numerically on the wet combustion of methane [33,32,34]. The setup of mesh and boundary conditions generally follows the previous work.…”

“…Li et al [27,28] studied MILD combustion using LES/PaSR model and found that autoignition and flame-like structures both play important roles in the combustion. Duwig's group conducted a sequence of works [29,30,31,32,33,34]. Duwig et al studied a propane-air fuelled flameless burner using LES with detailed chemistry.…”

“…The present work is one of a series of studies [32,33,34] focusing a better understanding of wet combustion technology and its application in gas turbines. This paper aims to fill in these knowledge gaps to facilitate the use of methanol in gas turbine and better understand the combustion properties of large alcohols.…”

Characterization of Distributed Combustion of Reformed Methanol Blends in a Model Gas Turbine Combustor

“…Li et al [27,28] studied MILD combustion using LES/PaSR model and found that autoignition and flame-like structures both play important roles in the combustion. Duwig's group conducted a sequence of works [29,30,31,32,33,34]. Duwig et al studied a propane-air fuelled flameless burner using LES with detailed chemistry.…”

“…The present work is one of a series of studies [32,33,34] focusing a better understanding of wet combustion technology and its application in gas turbines. This paper aims to fill in these knowledge gaps to facilitate the use of methanol in gas turbine and better understand the combustion properties of large alcohols.…”