Large Eddy Simulation of a Multiple-Injection Dry Low NOx Combustor for Hydrogen-Rich Syngas Fuel at High Pressure
Large Eddy Simulation of a Multiple-Injection Dry Low NOx Combustor for Hydrogen-Rich Syngas Fuel at High Pressure
复制标题
高压富氢合成气燃料多次喷射干式低氮氧化物燃烧室的大涡模拟
DOI：
10.1115/gt2016-58119
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Teruyuki Okazaki
中科院分区：
文献类型：
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作者：
K. Yunoki;Tomoya Murota;T. Asai;Teruyuki Okazaki
煤基综合气化联合循环（IGCC）技术的成功发展要求燃气轮机能够实现富氢合成气的干式低氮氧化物（NOx）燃烧，以实现低排放和高电厂效率。因此，我们一直在开发一种用于富氢合成气燃料的多喷嘴燃烧器，以实现高效率和低环境负荷。该燃烧器由带有多个气孔和燃料喷嘴的穿孔板组成。多个气孔与燃油喷嘴同轴布置。该燃烧器是基于预混燃烧的概念，通过将燃料和空气在每个空气孔中快速混合，并使用多个燃料-空气射流将燃料分散。这种快速混合可以通过获得均匀的贫预混燃烧来减少NOx排放，并且尽管富氢合成气燃料的火焰速度很高，但可以防止闪回。为了确认这一燃烧器概念，必须详细了解燃烧场中发生的非定常现象。然而，在高压下测量它们是困难的。同时，计算流体力学（CFD）能够研究高压高温燃烧场下各种排放和温度的详细分布。本文的目的是利用CFD对这一概念进行验证。燃烧器可以通过控制混合来改变预混燃烧和非预混燃烧之间的燃烧形式，因此预混燃烧和非预混燃烧并存的燃烧场是复杂的。因此，我们开发了一种混合湍流燃烧（HTC）模型，适用于非预混和预混火焰。HTC模型与火焰进程变量（FPV）模型和火焰传播模型混合。FPV模型是基于层流小火焰的概念。火焰传播模型考虑了火焰拉伸效应、扩散增强效应和火焰表面积增加速率。紊流模型采用基于局部尺度间平衡假设（LISEA4）的动态子网格尺度（SGS）大涡模拟（LES）。将湍流燃烧模型和湍流流动模型编程到基于OpenFOAM库的仿真工具中。我们通过仿真工具验证了该燃烧器用于富氢合成气燃料的概念。模拟结果表明，燃料与空气在气孔内快速混合，利用HTC模型确定了该多喷燃烧器的燃烧形态为预混燃烧。此外，多重喷射燃烧器具有较高的火焰稳定性。气孔内无高温区，燃烧器附近保持高温。因此，多重喷射燃烧器可以保持火焰稳定性，没有任何闪回。
The successful development of coal-based integrated gasification combined cycle (IGCC) technology requires gas turbines capable of achieving the dry low-nitrogen oxides (NOx) combustion of hydrogen-rich syngas for low emissions and high plant efficiency. Therefore we have been developing a multiple-injection burner for hydrogen-rich syngas fuel in order to achieve high efficiency and low environmental load. This burner consists of a perforated plate with multiple air holes and fuel nozzles. The multiple air holes and the fuel nozzles are arranged coaxially. The burner is based on the concept of premixed combustion configured by mixing fuel and air in the each air hole rapidly and dispersing fuel with multiple fuel-air jet. This rapid mixing can reduce NOx emissions by getting homogeneous lean premixed combustion, and preventing flashback despite the high flame speed for hydrogen-rich syngas fuels. The unsteady phenomena that occur in the combustion field should be understood in detail in order to confirm this burner concept. However, their measurement under high pressure is difficult. Meanwhile computational fluid dynamics (CFD) is able to investigate the detailed distributions of various emissions and temperature even though under combustion fields of high pressure and high temperature. The purpose of this paper is to validate this concept of the multiple-injection burner by using CFD. The burner can change the combustion form between premixed and non-premixed combustion by controlling the mixing, so the combustion field coexisting with premixed combustion and non-premixed combustion is complicated. Therefore, we have developed a hybrid turbulent combustion (HTC) model applicable to both non-premixed and premixed flames. The HTC model is hybridized with the flamelet progress variable (FPV) model and a flame propagation model. The FPV model is based on the laminar flamelet concept. The flame propagation model considers the flame stretch effect, diffusion enhancement effect, and increasing rate of flame surface area. The turbulent flow model adopts large eddy simulation (LES) with a dynamic sub-grid scale (SGS) based on the local inter-scale equilibrium assumption (LISEA4). Both the turbulent combustion model and turbulent flow model were programmed into a simulation tool based on the OpenFOAM library. We validated the concept of this burner for hydrogen-rich syngas fuel by using the simulation tool. The simulation results showed the rapid mixing of fuel and air in the air holes, and by using HTC model we confirmed that premixed combustion is the combustion configuration of this multiple-injection burner. In addition, the multiple-injection burner has high flame stability. There is no zone of high temperature in the air hole and high temperature is maintained near the burner. The multiple-injection burner can thus maintain flame stability without any flashback.