The migration and transformation mechanism of N in ammonia/coal volatile co-combustion: Experimental and quantum chemical calculation

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS
Ping Chen , Longxiang Qiao , Xiang Li , Mingyan Gu , Kun Luo , Xun Hu
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Abstract

It is very important to understand the NO formation characteristics and N conversion mechanism of ammonia/coal volatile combustion for low nitrogen combustion during ammonia-coal co-combustion. In this work, constant temperature furnace experiment and quantum chemistry calculation were used to study the migration and transformation characteristics of N for ammonia/coal volatile co-combustion. The experimental results showed that the ammonia blending ratio and temperature have significant effects on the formation of NO in volatile combustion. When the ammonia ratio was less than 10 %, volatile combustion preceded ammonia combustion, and unburned ammonia reduced part of NO at high temperature, so that the stable concentration of NO in ammonia/volatile combustion increased first and then decreased with the temperature increasing. The combustion performance of ammonia was enhanced with the further increase of ammonia blending ratio, and the stable concentration of NO in ammonia/volatile combustion gradually increased with the temperature increasing. The theoretical calculation showed that the ammonia/volatile co-combustion system firstly oxidized ammonia-N, and then oxidized C and N in the volatile. The addition of ammonia reduced the rate-limiting step barrier value of volatile-N oxidation about 53.11 kJ/mol or 99.11 kJ/mol, and promoted the formation of N-containing oxidation products in co-combustion system. The kinetic results showed that the rate-limiting step reaction rate of ammonia/volatile co-combustion system was about 2–4 orders of magnitude higher than that of pure volatile oxidation, and the formation rate of NO gradually increased with the increase of temperature. The theoretical calculation confirmed the experimental phenomenon and revealed the molecular mechanism of N conversion in ammonia/volatile combustion system.
氨/煤挥发性共燃烧中N的迁移转化机理:实验与量子化学计算
了解氨煤共燃过程中氨煤挥发性燃烧的NO生成特征和N转化机理对低氮燃烧具有重要意义。本文通过恒温炉实验和量子化学计算,研究了氨/煤挥发性共燃烧过程中N的迁移转化特性。实验结果表明,混氨比和温度对挥发性燃烧中NO的生成有显著影响。当氨比小于10%时,挥发性燃烧先于氨燃烧,未燃烧的氨在高温下还原了部分NO,因此氨/挥发性燃烧中NO的稳定浓度随温度升高先升高后降低。氨的燃烧性能随着氨掺比的进一步提高而增强,氨/挥发性燃烧中NO的稳定浓度随着温度的升高而逐渐升高。理论计算表明,氨/挥发物共燃系统首先氧化氨-N,然后氧化挥发物中的C和N。氨的加入降低了挥发性氮氧化的限速阶位值,分别为53.11 kJ/mol和99.11 kJ/mol,促进了共燃体系中含n氧化产物的生成。动力学结果表明,氨/挥发共燃烧体系的限速阶跃反应速率比纯挥发氧化体系高2 ~ 4个数量级,且NO的生成速率随着温度的升高而逐渐增大。理论计算证实了实验现象,揭示了氨/挥发性燃烧体系中N转化的分子机理。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of The Energy Institute
Journal of The Energy Institute 工程技术-能源与燃料
CiteScore
10.60
自引率
5.30%
发文量
166
审稿时长
16 days
期刊介绍: The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include: Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies Emissions and environmental pollution control; safety and hazards; Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS; Petroleum engineering and fuel quality, including storage and transport Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems Energy storage The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.
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