【作者】 张哲巅；

【导师】 肖云汉； 王岳；

【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， 2006， 博士

【摘要】 湿空气燃烧作为HAT、IGCC以及IGHAT等先进热力循环中的关键过程之一,其性能的优劣直接关系到热力循环系统的性能。因此本文针对构建循环的需要,对天然气和煤气化合成气在湿空气中的扩散燃烧进行了实验和数值研究,目的是更清晰、深入地理解湿空气燃烧的概念,从而对燃气轮机的湿空气燃烧操作和湿空气燃烧室的设计提供帮助。 首先研究了空气加湿对于火焰形态、尺寸和颜色的影响。通过实验研究发现,在加湿的同时增加燃料量,从而保持燃烧室出口温度相同的情况下,天然气火焰的尺寸随空气湿度的增加会大幅增加。而对于合成气火焰,空气加湿对于火焰尺寸的影响不明显。通过理论分析和数值模拟可以得知,空气加湿后氧浓度和流场的共同作用导致火焰尺寸改变。根据研究结果提出了改善甲烷—湿空气扩散火焰尺寸过大状况的措施,通过实验验证了该措施的可行性。 随后对湿空气扩散火焰的稳定性进行了研究。实验结果表明,甲烷—湿空气火焰的稳定性要比合成气—湿空气火焰差很多。通过分析和计算得出了甲烷火焰稳定性较差的原因,针对甲烷火焰提出了改善稳定性的措施,并且进行了实验验证。 最后对不同燃料湿空气燃烧的污染物生成和排放特性进行了研究。全尺寸燃烧室的实验结果表明,空气加湿对于碳氢燃料与合成气火焰污染物排放的影响不同,尤其是对CO排放的影响。针对在空气加湿影响CO排放方面存在的疑问,本文运用对冲扩散火焰从化学机理方面对其进行了计算分析。随后在模型燃烧室中对合成气—湿空气扩散火焰的CO排放机理进行了研究,发现CO排放并非随含空气湿量单调增加,而是先减后增。数值模拟的结果明确地解释了出现这种趋势的原因。 通过本文的研究,空气加湿影响扩散火焰和燃烧室性能的轮廓基本清晰。更多还原

【Abstract】 Humid air combustion is a key process of the advanced thermodynamical cycles such as HAT, IGCC and IGHAT, so its performance is directly related to the system performance of the thermodynamical cycles. Thus, according to the requirement of constructing the cycles, the diffusion combustion of natural gas and synthesis gas from coal gasification in humid air was studied experimentally and numerically. The purpose is to achieve more clear and deep understanding on the concept of humid air combustion and then help the operation on humid air combustion and humid air combustor design of gas turbines.First of all, the influence of humid air on flame shape, size and color was studied. It was found in the experiments that the size of natural gas flames significantly increased as the air became more humid under the condition the fuel flow rate was increased when increasing air humidity thus to keep the exit temperature of the combustor to be constant. While for the synthesis gas flames, the influence of air humidity on flame size is not so apparent. Via theoretical analysis and numerical simulation, it has been known that the change of flame size is induced by the comprehensive impact of the variation of oxygen concentration and flow field due to air humidification. On the basis of the previous study, a method for improving the condition that the size of methane-humid air flame is too large was proposed and the feasibility of the method was validated by experiments.Then the stability of diffusion flames in humid air was studied. The experimental results show that the stability of methane-humid air flames is much poor than that of synthesis gas-humid air flames. The reson of the poor stability of the methane flames was known via analysis and calculation. A method to improve the stability of the methaneflames was proposed and validated experimentally.Finally, the characteristics of pollutant generation and emission for the humid air combustion of different types of fuel were studied. The experimental results of a full-size combustor show that the influence of humid air on pollutant emission is different for hydro-carbon fuels and synthesis gas, especially on CO emission. Due to there exists some doubts on the influence of humid air on CO emission, the process was calculated and analyzed considering the chemical mechanism by using an opposed diffusion flame. Subsequently, the mechanism of CO emission of synthesis gas-humid air diffusion flames was studied by using a model combustor. It was found that the CO emission did not increase monotonically with air humidity. However, the CO emission would at first decrease and then increase. The results of numerical simulation clearly explained the reason of the exhibition of this trend.After the research work of the present study, the profile of the influence of humid air on diffusion flames and combustor performance becomes basically clear.更多还原