發(fā)布時(shí)間：2018-07-17 21:42

【摘要】：國(guó)內(nèi)燃機(jī)電廠普遍存在啟動(dòng)過程、低負(fù)荷工況下冒黃煙的問題,值班擴(kuò)散火焰污染物排放高是主因。蒸汽稀釋降低值班火焰污染物排放是一種可行的解決途徑。本文從零維分析入手,研究了蒸汽稀釋比和稀釋均勻性對(duì)天然氣擴(kuò)散火焰污染物生成的影響;采用三維模擬分析手段參數(shù)化研究了天然氣/蒸汽混合裝置關(guān)鍵結(jié)構(gòu)影響;最后,基于某值班擴(kuò)散燃燒器,實(shí)驗(yàn)研究了蒸汽稀釋天然氣擴(kuò)散燃燒的火焰結(jié)構(gòu)、污染物生成等特性。本論文主要工作如下:(1)基于CHEMKIN軟件平臺(tái)構(gòu)建了化學(xué)反應(yīng)網(wǎng)絡(luò)模型,建立了天然氣/蒸汽摻混不均勻度(Spatial Mixing Defficiency,SMD)模型,采用零維模擬手段定性分析了蒸汽稀釋比和稀釋SMD對(duì)CO、NOx生成的影響規(guī)律。結(jié)果表明,隨蒸汽稀釋比增加,NOx生成受到抑制,而CO生成增加;相同蒸汽稀釋比下,隨蒸汽稀釋SMD增加,CO、NOx生成均呈增加趨勢(shì),結(jié)果體現(xiàn)了改善天然氣/蒸汽摻混均勻性能的重要性。(2)針對(duì)天然氣和蒸汽的摻混裝置,選用SV靜態(tài)混合器結(jié)構(gòu)形式,數(shù)值模擬分析了混合單元數(shù)、混合單元傾角及混合單元間間隙對(duì)摻混性能的影響。確定了靜態(tài)混合器優(yōu)選結(jié)構(gòu)方案:混合單元數(shù)5,混合單元葉片傾角45°,混合單元間無間隙。(3)針對(duì)某應(yīng)用于燃?xì)廨啓C(jī)燃燒室的值班擴(kuò)散噴嘴,采用數(shù)值模擬結(jié)合實(shí)驗(yàn)研究的方法,研究了蒸汽稀釋比和稀釋均勻性對(duì)擴(kuò)散火焰特性和污染物排放的影響。結(jié)果表明,隨稀釋比增加,天然氣擴(kuò)散火焰OH強(qiáng)度變?nèi)?火焰結(jié)構(gòu)趨于緊湊,CO增加、NOx降低,但隨稀釋比進(jìn)一步增加,NOx減排收益降低,且火焰穩(wěn)定性下降;相同蒸汽稀釋比下,通過靜態(tài)混合器降低蒸汽稀釋SMD后,擴(kuò)散火焰結(jié)構(gòu)近似無變化,但反應(yīng)區(qū)OH峰值信號(hào)強(qiáng)度減弱,NOx、CO均呈下降趨勢(shì)。實(shí)驗(yàn)結(jié)果驗(yàn)證了改善蒸汽稀釋均勻性對(duì)值班擴(kuò)散火焰減排的有效性。本研究結(jié)果可為天然氣燃?xì)廨啓C(jī)解決啟動(dòng)過程中冒黃煙問題、拓寬低NOx工況范圍提供理論依據(jù)和實(shí)驗(yàn)數(shù)據(jù)參考。
[Abstract]:The problem of yellow smoke emission under low load condition and high pollutant emission from duty diffusion flame are the main causes of the start-up process in the power plants of internal combustion engine in China. Steam dilution is a feasible way to reduce the discharge of flame pollutants on duty. In this paper, the effects of steam dilution ratio and dilution uniformity on the formation of natural gas diffusion flame pollutants are studied, and the key structure of natural gas / steam mixing unit is parameterized by means of three-dimensional simulation analysis. Based on a duty diffusion burner, the flame structure and pollutant formation of steam diluted natural gas diffusion combustion were studied experimentally. The main work of this thesis is as follows: (1) based on the CHEMKIN software platform, the chemical reaction network model is constructed, and the spatial mixing efficiency SMD model is established. The effects of steam dilution ratio and diluted SMD on the formation of COO _ (no _ x) were qualitatively analyzed by means of zero dimensional simulation. The results showed that the formation of no _ x was inhibited with the increase of steam dilution ratio, and the formation of CO _ x increased with the increase of SMD at the same steam dilution ratio, and the formation of CO _ (no _ x) increased with the increase of SMD. The results show the importance of improving the homogeneity of natural gas / steam mixing. (2) for the mixing device of natural gas and steam, SV static mixer is selected and the number of mixing units is numerically simulated. The influence of the mixing angle and the gap between the mixing units on the mixing performance. The optimal structure scheme of static mixer is determined: the number of mixing units is 5, the blade inclination angle of mixing unit is 45 擄, and there is no gap between the mixing units. (3) for a duty diffusion nozzle used in a gas turbine combustor, a numerical simulation method combined with experimental study is adopted. The effects of steam dilution ratio and dilution uniformity on diffusion flame characteristics and pollutant emission were studied. The results show that with the increase of dilution ratio, the OH intensity of natural gas diffusion flame becomes weaker, the flame structure tends to be compact and CO increases and no _ x decreases, but with the increase of dilution ratio, the emission reduction income of no _ x decreases, and the flame stability decreases, and at the same steam dilution ratio, When the SMD was reduced by static mixer, the diffusion flame structure was almost unchanged, but the peak signal intensity of OH in the reaction region decreased and no _ x _ (10) CO decreased. The experimental results demonstrate the effectiveness of improving the uniformity of steam dilution on duty diffusion flame emission reduction. The results of this study can provide theoretical basis and experimental data reference for natural gas turbine to solve the problem of yellow smoke during start-up and to widen the range of low no _ x working conditions.
【學(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院工程熱物理研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM621;TK471

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本文編號(hào)：2131021