Reaction Characteristics of Coal/NH<sub>3</sub> Co-combustion Affected by the Highly Preheated Temperature under MILD Combustion Mode

LUO Junwei; ZHANG Zewu; ZHA Xiaojian; ZHAO Zhenghong; YANG Long; ZHANG Liqi

doi:10.6054/j.jscnun.2023060

Journal of South China Normal University (Natural Science Edition) > 2023 > 55(5): 31-38. > DOI: 10.6054/j.jscnun.2023060

LUO Junwei, ZHANG Zewu, ZHA Xiaojian, ZHAO Zhenghong, YANG Long, ZHANG Liqi. Reaction Characteristics of Coal/NH₃ Co-combustion Affected by the Highly Preheated Temperature under MILD Combustion Mode[J]. Journal of South China Normal University (Natural Science Edition), 2023, 55(5): 31-38. DOI: 10.6054/j.jscnun.2023060

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Reaction Characteristics of Coal/NH₃ Co-combustion Affected by the Highly Preheated Temperature under MILD Combustion Mode

1.
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
2.
Wuhan Boiler Energy Engineering Co., Ltd., Wuhan 430074, China

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Received Date: July 05, 2023
Available Online: January 21, 2024

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Abstract

Abstract

Co-combustion of coal blending with NH₃ is a promising technology to realize the large-scale CO₂ reduction in coal-fired plant. To offset the poor flammability of coal/NH₃ blend, an advanced moderate or intense low-oxygen dilution (MILD) combustion technology is implemented in coal/NH₃ co-combustion. The effects of the six different preheated temperatures from 1 173 K to 1 923 K on coal/NH₃ co-combustion under MILD mode are clarified based on the computional fluid dynamic software, i.e., ANSYS-FLUENT. Results show that, as the preheated temperature increases, the ignition of coal/NH₃ co-combustion is in advance. When the preheated temperature increases from 1 173 K to 1 923 K, the peak value of the furnace temperatres are increased from 1 823 K to 1 930 K, and the ignition times are in advance by 21.9%, and the ignition temperature and burnout time are reduced by 26.1% and 22.2%, respectively. These findings indicate that the high temperature can improve the ignition and burnout of coal/NH₃ co-combustion. In addition, the NO_x conversion ratio is increased from 2.78% to 3.25%, which is attributed to the decrease in the proportion of NO_x reduction (the decreases in the proportion of NH₃+NO pathway is from 38% to 30%). Although the highly preheated temperature is favorable to the ignition of coal/NH₃ co-combustion, it leads to an increase in fuel nitrogen conversion. Therefore, the regulation of the ammonia combustion reaction becomes the key to stable combustion and NO_x reduction. In the high temperature environment, reducing the local oxygen concentration in the reaction zone (e.g., air-staged combustion), promoting the reduction of NH₃ to NO, and inhibiting the conversion of NH₃ to NO will be expected to achieve stable combustion with low NO_x emission during coal/NH₃ co-combustion affected by the highly preheated temperature.
- low carbon combustion,
- coal/NH₃ co-combustion,
- preheating temperature,
- NO_x conversion

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References (23)

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