Oxidizer effects on ammonia combustion using a generated non-premixed burner

In the present study, the pure ammonia combustion in a model combustor is performed to seek ammonia-fueled applications. To this aim, effects of the oxygen enrichment with an oxygen concentration of 100% in the oxidizer on flame characteristics, temperature profiles and NO profiles during the ammonia combustion were evaluated in terms of excess air/ oxygen coefficients. Furthermore, in order to better understand the effect of an oxygen of 100% usage under the oxy-ammonia combustion conditions, the air-ammonia combustion has been studied as well and their results are compared and discussed each other. According to the results predicted, the oxidizer with an oxygen content of %100 provides better flame stability in the case of pure ammonia combustion. The most stable flame for oxy-ammonia combustion can be achieved when the excess oxygen coefficient is 1.0 or 1.2. Furthermore, the minimum NO levels emerge under the fuel-rich condition. Temperature and NO emissions decrease considerably under the air-ammonia combustion. However, except the fuel-rich conditions, flame stabilities are not satisfactory due to ammonia's flame speed under the air-ammonia combustion. Moreover, the air-ammonia combustion under the fuel-rich condition seems as a good option for obtaining the lowest NO levels. On the other hand, the oxy-enrichment condition is thought as a promising method for pure ammonia combustion provided that NO emissions should be optimized by using NO reduction methods.(c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, the combustion of pure ammonia in a model combustor was investigated to explore ammonia-fueled applications. The effects of oxygen enrichment on flame characteristics, temperature profiles, and NO profiles during ammonia combustion were evaluated, and compared with the combustion of air-ammonia mixture. The results showed that the use of an oxidizer with 100% oxygen content provided better flame stability in pure ammonia combustion. The most stable flame for oxy-ammonia combustion was achieved with an excess oxygen coefficient of 1.0 or 1.2, and the lowest NO levels were observed under fuel-rich conditions. The air-ammonia combustion resulted in a significant decrease in temperature and NO emissions, but flame stabilities were unsatisfactory except under fuel-rich conditions. The oxy-enrichment condition is considered a promising method for pure ammonia combustion, provided that NO emissions can be optimized with NO reduction methods.