Effects of organic silicon compounds on syngas auto-ignition behavior
Effects of organic silicon compounds on syngas auto-ignition behavior
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DOI：
10.1016/j.combustflame.2019.10.022
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发表时间：
2020-02
影响因子：
4.4
通讯作者：
R. A. Schwind;M. Wooldridge
中科院分区：
文献类型：
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作者：
R. A. Schwind;M. Wooldridge
硅氧烷是合成气原料中的重要杂质，也是燃烧合成中硅的重要来源。然而，对硅氧烷化合物的基本燃烧化学知之甚少。通过物理和计算实验，研究了三甲基硅醇和六甲基二硅氧烷这两种化学结构不同但又相互关联的有机硅物种对合成气自燃行为的影响。一种快速压缩装置被用来产生1010-1070atm K的温度和8-10.3atm的压力用于自动点火实验。在替代合成气混合物(CO和H_2的摩尔比为2.34：1，空气稀释水平，摩尔当量比为ϕ=0.1)中加入痕量TMO(摩尔数为100 ppm)或HMDSO(100 Ppm)的实验。点火延迟时间的测量表明，两种硅氧烷均能促进着火行为，与不含硅氧烷的合成气体混合物相比，TMO的着火延迟时间快约37%，HMDSO的着火延迟时间快约50%。对点火实验的结果进行了计算研究。由于这些有机硅化合物不存在详细的化学结构，因此我们研究了在H_2和CO体系中加入CH3、H和OH自由基的影响，以模拟硅氧烷在H_2和CO体系中潜在的快速分解。与没有自由基物种的H_2和CO混合物模拟相比，添加自由基使预测的点火延迟时间缩短，但模拟没有完全捕捉到实验中观察到的行为，这表明硅氧烷的化学比提供一个快速的自由基源要复杂得多。
Siloxanes are a significant impurity in syngas feedstocks and an important source of silicon in combustion synthesis applications. However, little is known regarding the fundamental combustion chemistry of siloxane compounds. The impact of two organic silicon species with different but related chemical structures, trimethylsilanol (TMSO) and hexamethyldisiloxane (HMDSO), on syngas auto-ignition behavior was investigated in this study using physical and computational experiments. A rapid compression facility (RCF) was used to create temperatures of 1010–1070 K and pressures of 8–10.3 atm for auto-ignition experiments. Experiments with trace concentrations of TMSO (100 ppm, mole basis) or HMDSO (100 ppm) were added to a surrogate syngas blend (CO and H2with a molar ratio of 2.34:1, air levels of dilution, with molar equivalence ratios of ϕ = 0.1). The measured ignition delay times showed both siloxane species promote ignition behavior with TMSO yielding faster ignition delay times by approximately 37% and HMDSO yielding faster times by approximately 50% compared with the reference syngas mixture which contained no siloxanes. A computational study was conducted to interpret the results of the ignition experiments. Because detailed chemistry does not exist for these organo-silicon compounds, the effects of the addition of CH3, H, and OH radicals to H2and CO mixtures were explored to simulate the potential rapid decomposition of the siloxanes in the H2and CO system. Addition of the radicals decreased the predicted ignition delay times when compared with the H2and CO mixture simulations without the radical species, but the simulations did not fully capture the behavior observed in the experiments, indicating the siloxane chemistry is more complex than providing a rapid source of radicals.