ABSTRACT

The pressurized oxy-fuel combustion is a promising CO₂ capture technology for its further reduction of CO₂ capture cost. In order to study the combustion behaviors of hydrocarbons under different pressures and atmospheres, a methane/air jet flame is used as the simulation target, with modifications on its oxidizer species and operating pressure. A Large Eddy Simulation (LES) with a tabulated chemistry model is employed, whose lookup tables are constructed by using a 2-D counterflow diffusion flame under different atmosphere and pressure conditions. The original flame with detailed experimental data is used for the validation of the model accuracy, and the simulation results show good agreement with the experiments. The detailed profiles of the temperature, species, and mixture fraction are analyzed. Compared with the air-fired, the flame in the oxy atmosphere is shorter and thinner. Important species and radicals are compared. The comparison shows that under elevated pressure, the differences caused by oxy atmosphere is similar to those found under atmospheric pressure. With the elevation of pressure from 0.1 MPa to 1.5 MPa, the flame height becomes smaller while the radial width is larger near the inlet, which can be observed in both air-fired and oxy-fired conditions. Under elevated pressures, the flame temperature changes slightly, but CO production increases noticeably in the fuel-rich regions.

摘要

加压全氧燃烧是一种很有前景的CO ₂捕集技术，可进一步减少CO ₂捕获成本。为了研究碳氢化合物在不同压力和气氛下的燃烧行为，以甲烷/空气喷射火焰为模拟目标，对其氧化剂种类和操作压力进行了修改。采用了带有表格化学模型的大涡模拟 (LES)，其查找表是通过在不同气氛和压力条件下使用二维逆流扩散火焰构建的。使用带有详细实验数据的原始火焰对模型精度进行验证，仿真结果与实验吻合较好。分析了温度、物质和混合分数的详细剖面。与空燃相比，氧气气氛中的火焰更短更薄。比较重要的物种和自由基。比较表明，在升高的压力下，氧气气氛引起的差异与大气压下的差异相似。随着压力从 0.1 MPa 升高到 1.5 MPa，火焰高度变小，而在入口附近的径向宽度变大，在空气燃烧和氧气燃烧条件下都可以观察到。在升高的压力下，火焰温度略有变化，但在富含燃料的地区，CO 产量显着增加。