【作者】 王智化；

【导师】 岑可法； 樊建人； 周俊虎；

【作者基本信息】 浙江大学 ， 工程热物理， 2005， 博士

【摘要】 随着我国经济社会的快速发展，能源与环境问题日益凸现。我国以燃煤为主的能源格局在相当长的一段时期内不会出现大的变化，而燃煤过程中产生的NO_x，SO₂，Hg等污染物对我国大气环境日益构成严重危害。目前针对各污染物开展逐一治理的做法不但浪费投资，而且增加额外运行费用，借鉴发达国家成功经验，开展燃煤多种污染物一体化协同脱除的研究具有重要意义。 针对目前我国脱硫正大量采用成熟湿法烟气脱硫WFGD技术，本文的研究主要以NO_x控制为侧重点，同时考虑与SO₂，Hg，HCI，HF等污染物的同时脱除。在对煤粉再燃、SNCR等机理研究的基础上，结合我国国情，提出了以污染物同时脱除、高效率、低投资、低运行成本为目的的多种技术有机组合应用新思路。国内首次提出了利用臭氧氧化结合碱液吸收的多种污染物一塔多脱新技术，并对炉内控制结合臭氧尾部多脱技术在300MW机组进行了初步方案设计，为我国污染物脱除领域提出了一条新的解决方案。针对扩散、混合过程对于各污染物控制过程中的重要影响，本文利用并行计算的方法，结合详细基元反应对二维反应射流进行了直接数值模拟，其中H₂／N₂火焰主要与加州大学Berkley分校Cabra博士的试验进行对比，以验证我们开发的并行反应射流程序的正确性，在此基础上对污染物脱除过程中O₃氧化NO_x过程进行了直接数值模拟，并对反应射流中涡的结构性状、运动特性以及合并撕裂过程进行了分析。 本文首先采用微观分析的方法对神华煤燃烧过程中燃料型NO_x的析出动态过程进行了跟踪分析，结果发现挥发份NO_x是燃料型NO_x的主要生成形式，占66.17～74.87％，高温条件下挥发份析出速率快，煤粉颗粒周围局部还原性气氛加强，NO_x析出总量减少，试验中1200℃相对1100℃和1000℃析出总量最少。挥发份析出时刻的氧量气氛对于挥发份NO_x的生成具有重要影响，本文首次引入挥发份化学当量比SRV的概念对其进行表征，传统一次风采取SRV=1.0～1.25的配风比例显然不利于低NO_x的控制，要有效抑制NO_x的生成，应在满足输送条件的基础上，至少控制SRV＜1.0。 在煤粉再燃机理研究过程中，采用管式炉微观堆积燃烧过程与沉降炉悬浮燃烧相结合的手段，对煤粉再燃微观机理、煤粉细度、再燃比例、温度、气氛等进行了分析。微观试验结果发现煤粉再燃过程呈典型的三阶段分布：1)．再燃煤粉早期NO_x生成过程，2)．挥发份均相还原过程和3)．焦炭非均相还原过程。第一阶段NO的生成与第三阶段焦炭非均相还原过程与O₂关系不大，而挥发份的均相还原对于环境O₂非常敏感，并且对于NO_x脱除作用最大，试验发现O₂量8％（SRV=1.27）是NO还原有效与否的分界线，要取得有效的脱硝效果O₂至少应小于5％（SRV＜0.8）。沉降炉中进行的试验结果表明：最佳再燃比例为20～25％，最佳再燃温度为1300℃，最佳再燃区化学当量比在0.8～1.0，再燃过程中的气氛控制比再燃比例更加重要，再燃区停留时间应在0.4～0.6s为更多还原

【Abstract】 With the rapid development of Chinese economic, the Energy and Environmental problems come up to the surface. Coal combustion is the main energy source in China recently and in the near future. Emissions such as NO_x, SO₂ and mercury during coal combustion is extraordinary harmful to our atmosphere. So far, individual control of pollutions is not only larger investment, but also additional application expenses needed. In view of successful experience from the developed countries, it is significantly important for simultaneous removal of multi-pollutions.With an eye on WFGD technology application in large scale as a method to desulfurization control for the present, this paper focuses on the NO_x removal, and multi-pollution control such as SO₂, Hg, HCl, HF are also concerned simultaneously . On the basis of coal Reburning and SNCR reaction mechanism research and the situation of our country, the paper brings out a new method which utilized the combination of some technologies for the purpose of multi-pollution removal, high efficiency, low investment and low consumption. It is first mentioned that using ozone oxidization to simultaneous control flue gas multi-pollutions in one alkali absorption tower. The initial proposal for multi-pollution control using ozone technology on 300MW power plant was carried out. This combination method for multi-pollutions control in furnace an in the flue gas brought a new solution for the pollution control. Regarding to the impact of diffusion and mixing on the pollution control process, two-dimension reaction jets flow was simulated using detail reaction mechanisms in direct numerical simulation （DNS） method. The purpose of H₂/N₂ jet flame was to confirm our parallel reaction DNS program by comparison with Cabra’s experiment. And then, the O₃/NO reaction jet was realized for pollution control process research. The vortex structure, shape, movement, combination and avulsion were also investigated.Firstly, the paper explored microcosmic method to analyze the fuel-NO_x emission process from Shenhua coal. Results show that the volatile-NO_x is the main component, which is 66.17～74.87% in the total NO_x. Higher temperature will accelerate the emission speed of volatile in coal particles, which will enhance the consumption of oxygen near the particle surface. This process will strengthen the fuel-rich condition at the moment of volatile combustion, which is believed benefit for low NO_x formation. In our experiment, the combustion condition at 1200℃ has the lowest amount of NO_x emission compared to 1100℃ and 1000℃. This paper first-adopts SRV to qualify the atmosphere of the volatile combustion moment. The traditional boiler design method at SRV=1.0～1.25 primary air更多还原