空气分级燃烧煤粉炉中H2S生成的详细反应机理研究

The air staged combustion technology can effectively reduce NOx emissions for pulverized coal boilers. However, a strong reducing atmosphere is formed in the fuel-rich area of the furnace. The atmosphere promotes the formation of high concentration H2S, which easily causes the serious high temperature corrosion of the water wall. In order to control the formation of H2S, it is very necessary to reveal the reaction mechanism of H2S formation and its kinetics principle. Currently, it is not comprehensive or accurate of the global reaction mechanism of H2S formation during air staged combustion, and moreover, there is not a specialized study on its detailed reaction mechanism and its kinetics principle is not clear. It cannot provide for the sufficient theoretical basis for controlling H2S formation. In view of this, the detailed reaction mechanism of H2S formation will be investigated in this project by applying an air staged combustion experimental furnace, Chemkin and Fluent, and using the experiment, theoretical analysis and numerical simulation devices. During this project, the global reaction mechanism will be clarified, and based on this, the detailed reaction mechanism and reduced reaction mechanism will be established. Furthermore, the controlling elemental reaction of H2S formation will be pointed out and the kinetics principle of H2S formation will be revealed from the free radical level. The implementation of this project is expected to provide the scientific basis for the pulverized coal boiler to control H2S formation and prevent the high temperature corrosion.

空气分级燃烧技术能够有效降低煤粉锅炉的NOx排放，但同时也在富燃料区形成了强还原性气氛，促进了高浓度H2S的生成，容易引发水冷壁的高温腐蚀。为控制H2S的生成，阐明H2S生成的反应机理及其动力学原理十分必要。当前，有关空气分级燃烧过程中H2S生成的总包反应机理还不够全面、准确，而且也没有针对H2S生成的详细反应机理进行研究，其动力学原理尚不清晰，不能为控制H2S生成提供充分的理论依据。鉴于此，本项目将利用空气分级燃烧煤粉炉实验装置、Chemkin以及Fluent模拟软件，采用实验表征、理论分析和数值模拟相结合的方法，开展空气分级燃烧煤粉炉中H2S生成的详细反应机理研究，阐明H2S生成的总包反应机理，并在此基础上构建H2S生成的详细反应机理和简化反应机理，找出H2S生成的控制基元反应，从自由基层面揭示H2S生成的动力学原理。本项目的实施可望为煤粉锅炉控制H2S生成、防止高温腐蚀提供科学依据。

空气分级燃烧技术能够有效降低煤粉锅炉的NOx排放，但同时在富燃料区形成了强还原性气氛，促进了H2S的生成，容易引发水冷壁的高温腐蚀。为找出控制H2S生成的有效方法，必须从自由基层面揭示H2S生成的动力学原理。详细反应机理考虑了各种自由基的相互作用，并详细描述了基元反应的动力学参数，可从自由基层面揭示H2S生成的动力学原理。然而，目前尚无针对空气分级燃烧过程中H2S生成的详细反应机理的专门研究。鉴于此，本项目利用空气分级燃烧煤粉炉实验装置、Chemkin以及Fluent等模拟软件，采用实验表征、理论分析和数值模拟相结合的方法，开展H2S生成的详细反应机理研究，阐明了空气分级燃烧过程中H2S生成的总包反应机理模型，并构建详细反应机理模型；进行了敏感性分析和生成速率分析，建立了H2S生成的简化反应机理模型，获得了H2S生成的重要基元反应和关键自由基。在此基础上，提出了多孔壁风耦合空气分级的煤粉燃烧技术，不仅能够抑制H2S的生成，而且降低了NOx排放、提高了燃烧效率。本项目的实施，从自由基层面揭示了H2S生成的动力学原理，为燃煤锅炉控制H2S生成和高温腐蚀防控提供理论依据。