發(fā)布時(shí)間：2018-01-04 22:01

  本文關(guān)鍵詞：丁醇摻混的甲烷同軸擴(kuò)散火焰的實(shí)驗(yàn)和動(dòng)力學(xué)研究　出處：《中國(guó)科學(xué)技術(shù)大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 甲烷 丁醇 常壓層流擴(kuò)散火焰 同步輻射真空紫外光電離質(zhì)譜 燃燒反應(yīng)動(dòng)力學(xué)模型 多環(huán)芳烴 碳煙生成機(jī)理 laminarSMOKE

【摘要】：隨著人口和經(jīng)濟(jì)的增長(zhǎng),人類社會(huì)對(duì)于能源的需求也飛速增長(zhǎng),導(dǎo)致作為主要能源的石油和煤等化石燃料的急劇消耗。同時(shí)主要由碳?xì)淙剂辖M成的化石燃料的燃燒會(huì)導(dǎo)致嚴(yán)重的大氣污染問題,日益侵害著環(huán)境安全和人類健康。因此,為實(shí)現(xiàn)社會(huì)的可持續(xù)發(fā)展,高效清潔燃燒技術(shù)和可再生燃料的發(fā)展迫在眉睫。然而,雖然人類利用化石燃料的時(shí)間已達(dá)數(shù)千年之久,但對(duì)于其燃燒污染物生成機(jī)理的研究仍無(wú)法從根本上滿足燃燒污染物防治要求。另一方面,生物質(zhì)燃料是目前重要的可再生能源之一,多與化石燃料摻混應(yīng)用于內(nèi)燃機(jī)燃燒。丁醇與常用的乙醇相比具有更高的熱值、更好的發(fā)動(dòng)機(jī)兼容性和更加便利的存儲(chǔ)條件,是極富潛力的新型生物質(zhì)燃料。當(dāng)前對(duì)生物質(zhì)燃料排放的新型燃燒污染物及與碳?xì)淙剂蠐交旌蟮娜紵匦缘难芯可刑幊跫?jí)階段,難以滿足生物質(zhì)燃料的發(fā)展與應(yīng)用需求。因此,亟需研究生物質(zhì)燃料與碳?xì)淙剂系膿交烊紵捌浞磻?yīng)動(dòng)力學(xué)機(jī)理,為工程燃燒應(yīng)用提供理論指導(dǎo)。甲烷是清潔化石燃料天然氣的主要組分,也是最常見、動(dòng)力學(xué)模型發(fā)展最為成熟的碳?xì)淠Ｐ腿剂稀Ｒ虼吮菊撐倪x取甲烷作為同軸擴(kuò)散火焰的基礎(chǔ)燃料,研究碳?xì)淙剂先紵卸喹h(huán)芳烴(PAH)和碳煙等燃燒污染物的形成機(jī)理,以及丁醇異構(gòu)體的摻混對(duì)芳烴污染物產(chǎn)率的影響,特別著眼于實(shí)際燃燒中擴(kuò)散效應(yīng)和物質(zhì)分布不均勻性引起的污染物形成機(jī)理的改變。同軸擴(kuò)散火焰是一種非常接近實(shí)際燃燒狀態(tài)的實(shí)驗(yàn)室火焰,耦合了物質(zhì)擴(kuò)散和化學(xué)反應(yīng)對(duì)于火焰結(jié)構(gòu)的雙重影響,特別是易于形成多環(huán)芳烴和碳煙,是研究多環(huán)芳烴和碳煙形成機(jī)理的理想火焰。 在實(shí)驗(yàn)研究方面,本工作于國(guó)際上首次將同步輻射真空紫外光電離質(zhì)譜技術(shù)(SVUV-PIMS)應(yīng)用于同軸擴(kuò)散火焰結(jié)構(gòu)診斷,研究了不同氮?dú)庀♂尡壤某杭淄閿U(kuò)散火焰,以及四種丁醇異構(gòu)體以不同比例摻混的常壓甲烷擴(kuò)散火焰。實(shí)驗(yàn)采用石英探針對(duì)同軸擴(kuò)散火焰進(jìn)行取樣,取樣得到的燃燒產(chǎn)物由SVUV-PIMS技術(shù)進(jìn)行定性分析和定量測(cè)量。實(shí)驗(yàn)中,通過掃描光電離質(zhì)譜和光電離效(PIE)率譜,得到了燃燒物種的分子量和電離能信息,從而在同軸擴(kuò)散火焰中鑒別出了數(shù)十種分子量介于2至240之間的燃燒物種。除燃料、氧化劑和稀釋氣體外,還包括主要燃燒產(chǎn)物(H2、H2O、CO和C02)、自由基、穩(wěn)定的小分子中間體、單環(huán)芳烴(MAH)和多環(huán)芳烴。另外,通過在不同光子能量下掃描火焰的中心軸線位置,獲得了這些燃燒物種的摩爾分?jǐn)?shù)沿中心軸線方向的空間分布情況。 在模型研究方面,本工作發(fā)展了一個(gè)全新的丁醇燃燒反應(yīng)動(dòng)力學(xué)模型,由甲烷核心機(jī)理、丁醇子機(jī)理和芳烴子機(jī)理構(gòu)成。甲烷核心機(jī)理是在USC Mech Ⅱ機(jī)理的基礎(chǔ)上,結(jié)合最新C0-C4核心機(jī)理的理論和模型成果進(jìn)行深度發(fā)展而成的。丁醇子機(jī)理和芳烴子機(jī)理則是在本課題組之前的丁醇同分異構(gòu)體燃燒反應(yīng)動(dòng)力學(xué)模型和芳烴燃燒反應(yīng)動(dòng)力學(xué)模型的基礎(chǔ)上分別發(fā)展而成的,對(duì)芳烴子機(jī)理還進(jìn)行了一定的精簡(jiǎn),以確保數(shù)值模擬效率。本工作采用的模型研究思路是先利用甲烷和丁醇各自的基礎(chǔ)燃燒實(shí)驗(yàn)數(shù)據(jù)進(jìn)行模型驗(yàn)證,確保各部分子機(jī)理的準(zhǔn)確性,再開展同軸擴(kuò)散火焰數(shù)值模擬的策略。其中,兩類燃料的理想反應(yīng)器實(shí)驗(yàn)驗(yàn)證采用的是OpenSMOKE軟件,而同軸擴(kuò)散火焰的燃燒數(shù)值模擬采用的是國(guó)際上先進(jìn)的laminarSMOKE軟件。用于模型驗(yàn)證的甲烷和丁醇文獻(xiàn)實(shí)驗(yàn)數(shù)據(jù)包括火焰?zhèn)鞑ニ俣纫约傲鲃?dòng)管熱解、射流攪拌反應(yīng)器氧化、層流預(yù)混火焰和對(duì)沖擴(kuò)散火焰中的物種濃度等。在本工作的同軸擴(kuò)散火焰模擬工作中,還進(jìn)一步對(duì)芳烴子機(jī)理進(jìn)行了驗(yàn)證和發(fā)展。通過對(duì)模擬結(jié)果和實(shí)驗(yàn)結(jié)果進(jìn)行對(duì)比,結(jié)合相關(guān)文獻(xiàn)的研究成果,增加了必要的反應(yīng)路徑、剔除了不合理的反應(yīng)路徑、更正了不準(zhǔn)確的速率常數(shù),從而完善并優(yōu)化了丁醇燃燒反應(yīng)動(dòng)力學(xué)模型。 基于理想反應(yīng)器實(shí)驗(yàn)?zāi)M和同軸擴(kuò)散火焰的數(shù)值模擬結(jié)果,本論文對(duì)甲烷的燃燒過程進(jìn)行了詳細(xì)的動(dòng)力學(xué)分析。重點(diǎn)對(duì)同軸擴(kuò)散火焰中燃料的分解路徑、重要芳烴前驅(qū)體的生成與消耗路徑、苯和典型多環(huán)芳烴的生成路徑進(jìn)行了深入的生成速率分析和敏感性分析。結(jié)果表明,在甲烷擴(kuò)散火焰中心線上,甲烷主要分解產(chǎn)生甲基,由甲基的自復(fù)合反應(yīng)及其產(chǎn)物后續(xù)的分解反應(yīng)產(chǎn)生乙烷、乙烯等穩(wěn)定的C2小分子中間體以及乙基、乙烯基等C2活潑自由基。它們?cè)俜纸猱a(chǎn)生的乙炔會(huì)和甲基進(jìn)行復(fù)合反應(yīng),并最終反應(yīng)形成重要的芳烴前驅(qū)體——炔丙基,后者的自復(fù)合反應(yīng)是形成苯的重要路徑。在擴(kuò)散火焰的芳烴生長(zhǎng)過程中,苯和苯基是大多數(shù)芳烴物種生長(zhǎng)的起點(diǎn),特別是芐基和單環(huán)芳烴的生成直接依賴于苯基與C1-C2中間體的反應(yīng)�；鹧嬷械男》肿又虚g體,如乙炔、丙炔、丁二烯以及炔丙基、乙烯基等自由基,與苯、苯基和芐基等的反應(yīng)最終會(huì)形成雙環(huán)芳烴,例如萘和茚主要由苯、苯基和芐基與C2-C3中間體反應(yīng)得到。多環(huán)芳烴自由基,如茚基和萘基等在由雙環(huán)芳烴向更大的多環(huán)芳烴的生長(zhǎng)過程中起到重要的作用。與此同時(shí),在甲烷擴(kuò)散火焰中,隨著燃料端氮?dú)獗壤脑黾?燃料稀釋效應(yīng)引起了火焰溫度的下降,從而引起芳烴前驅(qū)體、苯和多環(huán)芳烴產(chǎn)量的明顯下降。這些都在本論文的各個(gè)章節(jié)中進(jìn)行了深入分析。 根據(jù)甲烷擴(kuò)散火焰中的經(jīng)驗(yàn),在甲烷摻混丁醇同分異構(gòu)體擴(kuò)散火焰中我們保持了在兩種不同丁醇摻混比例條件下火焰碳流量的恒定,這使得火焰溫度和主要產(chǎn)物的摩爾分?jǐn)?shù)在兩種情況下幾乎完全一致,從而凸現(xiàn)出丁醇摻混比例提高所引起的燃燒中間體濃度的顯著變化。芳烴的生成隨著丁醇摻混比的提高體現(xiàn)出較強(qiáng)的規(guī)律性,苯、甲苯、茚、萘等芳烴的濃度隨丁醇摻混比例的提高而不斷提高。在甲烷及丁醇摻混的甲烷火焰中,多環(huán)芳烴的主要生成路徑均是苯、苯基和芐基與小分子中間體之間的反應(yīng),即苯是這一系列火焰中芳烴生長(zhǎng)過程的起點(diǎn)和最重要的多環(huán)芳烴前驅(qū)體。丁醇的添加對(duì)甲烷同軸擴(kuò)散火焰中苯和多環(huán)芳烴的生成具有促進(jìn)作用,并且隨著丁醇異構(gòu)體分子支鏈復(fù)雜程度的增加而加強(qiáng)。在火焰中丁醇主要通過單分子解離反應(yīng)和由H原子或甲基進(jìn)攻引發(fā)的H提取反應(yīng)產(chǎn)生燃料分子自由基,后經(jīng)β解離形成小分子碳?xì)浠蚝趸衔�。這些中間體或繼續(xù)分解或和甲基反應(yīng)形成芳烴前驅(qū)體,從而影響芳烴在不同丁醇異構(gòu)體摻混的火焰中的濃度。就C6以下碳?xì)渲虚g體而言,丁醇同分異構(gòu)體的添加對(duì)其主要分解產(chǎn)物濃度的影響最為明顯,例如正丁醇對(duì)C2中間體影響巨大,而叔丁醇則主要影響C3和C4中間體。因?yàn)樵诙〈紦交斓募淄榛鹧嬷?苯的生成路徑存在著較大的共性,絕大部分來(lái)自于炔丙基和C3物種的復(fù)合反應(yīng),而叔丁醇和異丁醇這兩種支鏈結(jié)構(gòu)的丁醇異構(gòu)體相比正丁醇和仲丁醇這兩種直鏈結(jié)構(gòu)的能夠更直接有效的提供C3中間產(chǎn)物,因此在它們摻混的甲烷火焰中生成了更多的苯。此外,炔丙基和乙烯基乙炔復(fù)合生成的甲苯能分解成芐基,這是另一種重要的芳烴前驅(qū)體。仲丁醇和叔丁醇相比另外兩種丁醇異構(gòu)體更容易分解產(chǎn)生1,3-丁二烯和乙烯基乙炔等不飽和C4烴類。因此,它們各自比擁有相同碳鏈結(jié)構(gòu)的另一種異構(gòu)體更容易生成甲苯和芐基。同時(shí),多環(huán)芳烴的生成依賴于苯、苯基和芐基與C1-C3等小分子中間產(chǎn)物的多步加成或復(fù)合反應(yīng),容易生成苯和甲苯的火焰更容易產(chǎn)生多環(huán)芳烴,這是丁醇摻混的同軸擴(kuò)散火焰中芳烴生長(zhǎng)路徑的共同特點(diǎn)。所以最終我們?cè)趯?shí)驗(yàn)和數(shù)值模擬結(jié)果中一致發(fā)現(xiàn)芳烴生成濃度的趨勢(shì)是：叔丁醇異丁醇仲丁醇正丁醇。
[Abstract]:With the development of economy and population, the human society is the rapid growth of the demand for energy, resulting in sharply as the main energy consumption of oil and coal and other fossil fuels. At the same time, mainly composed of hydrocarbon fuel in the combustion of fossil fuels will lead to serious air pollution problems, increasingly harming the environment and human health. Therefore, for realize the sustainable development of the society, the development of efficient and clean combustion technology and renewable fuels imminent. However, although the human use of fossil fuels has time for thousands of years, but the research on its combustion pollutant formation mechanism is still not fundamentally meet the requirements of prevention and control of combustion pollutants. On the other hand, biomass fuel is one of the most important renewable energy and fossil fuel combustion. Mixing for butanol and ethanol compared with common higher calorific value, better start Machine compatibility and more convenient storage conditions, is a new type of biomass fuel has the potential to study. The new combustion emissions of pollutants of the biomass fuels and hydrocarbon fuel mixed combustion characteristics is still in the primary stage, it is difficult to meet the development of biomass fuels and application. Therefore, an urgent need to study biomass fuels and hydrocarbon fuel the mixing and combustion reaction mechanism, to provide theoretical guidance for the engineering application of combustion. Methane is a major group of clean fossil fuel gas, which is the most common, the most mature model of hydrocarbon fuel based fuel dynamics model development. This paper selects the methane as coaxial diffusion flame, combustion of hydrocarbon fuel in polycyclic aromatic hydrocarbons (PAH) formation mechanism and soot combustion pollutants, and butanol isomers of the mixing effect on the yield of aromatic hydrocarbons, with particular emphasis on The actual combustion diffusion effect and the material caused by the uneven distribution of pollutant formation mechanism. The change of coaxial diffusion flame is a kind of very close to the actual laboratory flame combustion status, coupling material diffusion and chemical reaction double effects on flame structure, especially the easy formation of polycyclic aromatic hydrocarbons and soot, is an ideal flame formation mechanism research polycyclic aromatic hydrocarbons and soot.
In the experiment, the technique on ionization mass spectrometry for the first time the international synchrotron radiation vacuum ultraviolet light (SVUV-PIMS) applied to the coaxial diffusion flame diagnosis structure, atmospheric methane diffusion flame with different nitrogen dilution ratio of atmospheric methane, and four butanol isomers with different proportion of mixed diffusion flame experiment using quartz. Probe to sampling the coaxial diffusion flame, combustion product sampling by qualitative analysis and quantitative measurement by SVUV-PIMS technology. In the experiment, by scanning photoionization mass spectra and photoionization efficiency (PIE) spectrum, the combustion species of molecular weight and ionization energy information, resulting in the coaxial diffusion flame identified dozens of the molecular weight between 2 to 240 species combustion. In addition to fuel, oxidant and dilution gas, including main combustion products (H2, H2O, CO and C02), free radicals, small molecules in the stable Intermediates, mono cyclic aromatic hydrocarbons (MAH) and polycyclic aromatic hydrocarbons. In addition, the spatial distribution of mole fraction of these combustion species along the central axis is obtained by scanning the central axis of the flame at different photon energies.
In this model, we developed a new butanol combustion reaction kinetics model by methane core mechanism, form mechanism and mechanism of sub sub butanol aromatics. Methane core mechanism is based on USC Mech II mechanism, combined with the latest C0-C4 core mechanism theory and the model results are the depth of evolution. Butanol and aromatic sub sub mechanism is the foundation mechanism before the research group of the butanol isomers combustion reaction kinetics and aromatic hydrocarbon combustion reaction kinetics respectively on the development and mechanism of aromatic sub also carried out some simplification, to ensure the efficiency of the numerical simulation. The research ideas used in this model is the first use of methane and the butanol combustion experiment data to validate the model, to ensure the accuracy of each part of the sub mechanism, and then carry out numerical simulation of the diffusion flame in the coaxial strategy. Experiment two, ideal reactor fuel is used in OpenSMOKE software, and the coaxial diffusion flame combustion numerical simulation using the international advanced laminarSMOKE software for model validation. The methane and butanol experimental data including flame propagation velocity and flow tube pyrolysis, jet stirred reactor oxidation, laminar premixed flame and the species concentration in flame diffusion. In this work the coaxial diffusion flame simulation, further on the aromatic sub mechanism was verified and developed. Through the comparison of simulation results and experimental results, combined with the research results of related literature, increase the reaction path necessary, eliminating the unreasonable reaction path correct, rate constants are not accurate, so as to improve and optimize the butanol combustion reaction kinetics model.
The numerical simulation results of ideal reactor simulation experiment and coaxial diffusion flame based on the detailed analysis of the dynamics of the combustion process of methane decomposition. The key path of the coaxial diffusion flame fuel path, production and consumption of aromatics precursors, the generated path of benzene and polycyclic aromatic hydrocarbons are the typical formation rate analysis and the sensitivity of in-depth analysis. The results show that the methane diffusion flame center line, mainly due to decomposition of methyl methane, ethane produced by the decomposition reaction of composite reaction and its products following methyl, vinyl stable C2 small molecule intermediates and ethyl vinyl, C2 active radicals. They then decompose acetylene and methyl for the complex reaction of aromatic precursor and eventually formed by reaction of propargyl -- important, since the latter complex reaction is an important path to the formation of benzene in expanding. Aromatic powder flame growth process, benzene and phenyl is the starting point for most aromatic species growth, especially the formation of benzyl and monocyclic aromatic hydrocarbons depend directly on phenyl and C1-C2 intermediate reaction. Small molecule intermediates in the flame, such as acetylene, methylacetylene, butadiene and Que Bingji, vinyl and other free radicals, and benzene. The reaction of phenyl and benzyl will eventually form bicyclic aromatic hydrocarbons, such as naphthalene and indene obtained mainly by benzene, phenyl and benzyl and C2-C3 intermediates. Polycyclic aromatic hydrocarbon free radicals, such as indenyl and naphthyl in growth process by PAHs to polycyclic aromatic hydrocarbons in greater play an important role. At the same time, the methane the diffusion flame, with the increase of fuel nitrogen proportion end, fuel dilution effect caused by the decrease of flame temperature, causing the aromatic precursors, benzene and polycyclic aromatic hydrocarbons yield decreased significantly. These are the various An in-depth analysis is carried out in the chapter.
According to the experience of methane diffusion flame, mixed butanol isomers in a diffusion flame we kept under two different conditions of mixing ratio of butanol flame carbon flow constant in methane mixing, the mole fraction of the flame temperature and the main products in the two cases are almost identical, which highlights the significant content of butanol change the concentration of combustion intermediates caused by improving the mixing ratio. The formation of the aromatics with butanol mixed ratio increase reflects the strong regularity, benzene, toluene, naphthalene and other aromatic indene, with butanol mixed proportion and constantly improve. The methane and methane flame in butanol mixing, mainly generated the path of polycyclic aromatic hydrocarbons are benzene, between phenyl and benzyl with small molecular reaction intermediates, namely benzene is the starting point of growth process of a series of aromatic hydrocarbons in the flame and the most important PAHs precursor. The addition of butanol On the formation of methane CO diffusion benzene and polycyclic aromatic hydrocarbons in the flame has a promoting effect, and increases with the increasing of the molecular complexity of the butanol isomers branched. Butanol in flames by unimolecular dissociation reaction induced by H and atomic attack or methyl H extraction reaction to produce fuel radicals, after the formation of small beta dissociation molecular hydrocarbon or oxygen-containing compounds. These intermediates or continue the decomposition or reaction of methyl aromatics and the formation of the precursor, thus affecting the concentration of aromatic hydrocarbons in different butanol isomers mixing flame. C6 following hydrocarbon intermediates, butanol isomers of the effects on the main decomposition products of concentration is most obvious, for example n-butanol is the intermediate of C2 impact, and tert butyl alcohol mainly affects C3 and C4 intermediates. Because methane flame in butanol mixing in the path of benzene has a greater total Of complex reaction comes from the vast majority of propargyl and C3 species, and butanol isomers of branched chain structures of these two kinds of tert butyl alcohol and isobutyl alcohol compared to n-butanol and butanol these two kinds of straight chain structure more directly and effectively provide the intermediate product of C3, so the methane flame in their mixing in generation more benzene. In addition, propargyl and vinyl acetylene compound generated by toluene can be decomposed into benzyl radical, which is another important aromatic precursor. Butanol and tert butyl alcohol compared to the other two butanol isomers more easily decomposed into 1,3- butadiene and vinyl acetylene and other unsaturated hydrocarbons. Therefore C4 each of them, than the other isomers with the same carbon chain structure facilitates the formation of toluene and benzyl. At the same time, the PAHs formation depends on benzene, phenyl and benzyl C1-C3 and small molecule intermediates of multi-step addition or composite reaction, easy to A benzene and toluene flame more prone to polycyclic aromatic hydrocarbons, which is coaxial mixing diffusion characteristics of butanol aromatic growth path flame. So in the end we in the experimental and numerical simulation results consistently found that the concentration of aromatic trend: tert butyl alcohol butanol isobutanol n-butanol.

【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TK16

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 李玉陽(yáng);芳烴燃料低壓預(yù)混火焰的實(shí)驗(yàn)和動(dòng)力學(xué)模型研究[D];中國(guó)科學(xué)技術(shù)大學(xué);2010年

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本文編號(hào)：1380255