A distributed fuel injection enabled approach for two-zone combustion of methane-ammonia-air mixtures

Document Type

Conference Proceeding

Publication Date

1-1-2023

Abstract

A number of initiatives are underway to minimize greenhouse gas emissions caused by the use of hydrocarbon fuels in power generation, which is a major contributor to global climate change. Ammonia is considered a prospective replacement for hydrocarbon fuels, whose application to commercial combustion systems is impeded by its NOx emission and by combustion stability concerns. A two stage combustion approach, with rich and lean equivalence ratio, has shown to significantly decrease the NOx emission levels, which forms the objective of the current work. This ongoing work has considered premixed combution of methane-ammonia-air mixtures using experiments and simulations. The experimental approach utilizes a two-stage combustor, where combustion is based on rich-lean combustion approach (RQL method). The primary stage includes a swirler with novel distributed fuel injection, while the second stage includes a radial secondary air injection module. The corresponding numerical simulations have been performed using a chemical reactor network. The numerical simulations were conducted for a range of primary (1.1 − 1.3%) equivalence ratio and methane/ammonia mixture fractions (0 − 70%), with secondary stage equivalence ratio set at 0.5. From the results, a minimum of 55% decrease in NOx levels can be expected in two-stage approach, in comparison to a single stage combustor. The injection of cold air in second stage had not effect on thermal performance of the combustor. The trend of major NOx generation pathways were similar in primary and secondary stages, but they differed in specific reaction mechanisms with maximum reaction rate. This differences could be attributed to differences in inlet composition and inlet temperatures, at the primary and secondary stages. The overall goal of the current work will be to explore and demonstrate means of achieving optimal combustion of ammonia-methane-air mixtures, using a two-zone combustor approach, to minimize NOx emissions, while ensuring complete reactant conversion and associated energy release.

Publication Source (Journal or Book title)

AIAA SciTech Forum and Exposition, 2023

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