【作者】 胡宏斌；

【导师】 黄伟光； 徐纲；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2011， 博士

【摘要】 随着我国节能减排政策的实施,国家对钢铁行业的能耗提出了具体的目标。如何实现低热值气体燃料的高效利用将成为钢铁企业节能减排的关键。低热值气体燃料在燃烧过程中遇到的主要问题是：热值较低使得燃料点火困难,燃烧稳定性较差,容易发生熄火现象。非平衡等离子体助燃技术具有解决低热值气体燃料点火困难以及燃烧不稳定问题的潜力。非平衡等离子体助燃技术是在工作气体(燃料、氧化剂或者可燃混合气)中进行放电,利用产生的非平衡等离子体的化学活性提高燃料的点火性能及燃烧特性的技术。本文的研究目的是利用放电产生的非平衡等离子体改善低热值气体燃料的燃烧特性以提高其点火可靠性和燃烧稳定性。本文首先设计了一种适用于助燃低热值气体燃料的等离子体发生装置,研究了该装置的放电特性和规律,分析了放电过程中各种活性基团的种类、产生过程及其相互之间的反应机理。随后利用该装置产生的等离子体对低热值气体燃料进行助燃,研究了低热值气体燃料的点火性能、熄火极限、火焰传播速度、燃烧效率、火焰形态等重要参数在等离子体助燃的影响下的变化规律。而后采用数值模拟的方法进一步深入研究了等离子体对于低热值气体燃料的点火过程和燃烧过程产生的影响,分析其影响机理。在对等离子体助燃进行实验研究和数值模拟的基础上,作者对等离子体助燃的机理进行初步的归纳和总结。最后本文把等离子体助燃技术与目前燃气轮机中普遍采用的旋流扩散燃烧技术相结合,设计了一种能够助燃旋流火焰的等离子体发生装置,研究了旋流火焰在等离子体助燃下的燃烧特性,为等离子体助燃技术向工程实用方向发展打下了基础。本文的研究中得到的主要结论包括：1、通过介质阻挡放电的方式能够产生大体积、高密度、富含活性粒子的非平衡等离子体；2、在非平衡等离子体的助燃下,低热值气体燃料的燃烧特性得到了显著的改善,主要体现在：点火可靠性增强、熄火极限拓宽、火焰传播速度增大、火焰根部的燃烧更加稳定、火焰中心区域的温度更高；3、非平衡等离子体助燃的机理可以归纳为温升效应和化学效应；4、在等离子体旋流器的作用下,火焰的旋流强度增大,燃料和空气的掺混更加充分,燃烧稳定性和燃烧效率都得到提升。更多还原

【Abstract】 As the implementation of the policy of "energy saving and emission reduction" by the government, the steel industry need to find a more efficient way of using of low-BTU gas fuels. Low-BTU gas fuel is difficult to be ignited, and the flame is extremely unstable, and easily blown off. Non-equilibrium plasma assisted combustion technology might be a potential way to achieve reliable ignition and flame stabilization. Non-equilibrium plasma is generated by an electrical discharge through working gas (fuel, oxidant, or combustible mixture). The production of atoms, ions, and active radicals can significantly promote the process of chemical reactions.This paper mainly focuses on reliable ignition and flame stabilization of low-BTU gas fuels through the use of non-equilibrium plasma generated by an electrical discharge. First, an electrical discharge is designed to generate plasma. We learn the characteristics of the discharge, and analyze the production of active species in the discharge field. Then, we use the plasma generated by the discharge assisted the combustion process of low-BTU fuels. The changes of ignition ability, blow-off limits, flame speed, combustion efficiency and flame structure are observed. In order to analyze the influence of plasma deeply, we establish the numerical model of plasma assisted combustion process. Based on results of experiments and numerical simulation, mechanisms of plasma assisted combustion are ascertained. Finally, a plasma swirler is designed and the experiments are carried out to verify the feasibility of using plasma swirler to control diffusion flame.Main conclusions in this paper are below:1. Dielectric barrier discharge (DBD) can generate large volume, high concentration non-equilibrium plasma at atmosphere pressure.2. With the support of DBD plasma, the combustion characteristics of low BTU-fuels are improved a lot, including:more reliable ignition, wider blow-off limits, increased flame speed, and higher flame temperature.3. Mechanisms of plasma assisted combustion are ascertained to be results of raise of temperature and acceleration of chemical reactions.4. The plasma swirler can enhance combustion stability through ionizing the air to produce active free radical and promoting the swirling air.更多还原