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開(kāi)口管道煤塵—甲烷預(yù)混火焰動(dòng)力學(xué)特性研究

發(fā)布時(shí)間:2018-04-13 19:00

  本文選題:煤塵-甲烷預(yù)混燃燒 + 火焰?zhèn)鞑ソY(jié)構(gòu); 參考:《武漢理工大學(xué)》2015年碩士論文


【摘要】:課題通過(guò)搭建煤塵-甲烷預(yù)混物燃燒火焰特性實(shí)驗(yàn)平臺(tái),結(jié)合高速攝像機(jī)、數(shù)據(jù)采集儀和溫度傳感器等,測(cè)量得到不同條件下煤塵-甲烷預(yù)混燃燒火焰?zhèn)鞑バ螒B(tài)圖、傳播速度、溫度等火焰?zhèn)鞑ヌ卣鲄?shù),并分析煤塵-甲烷預(yù)混燃燒火焰的傳播特性以及煤塵粒徑和甲烷濃度對(duì)混合物燃燒火焰?zhèn)鞑ヌ匦缘挠绊。得出以下結(jié)論:(1)煤塵-甲烷預(yù)混燃燒火焰?zhèn)鞑バ螒B(tài)以及燃燒強(qiáng)度與甲烷濃度以及煤塵粒徑密切相關(guān)。甲烷濃度為3.7%時(shí),火焰前鋒呈離散不規(guī)則狀態(tài),而當(dāng)甲烷濃度增大為4.5%、6.7%時(shí),火焰前鋒呈較規(guī)則的平面或拋物面;當(dāng)煤塵粒徑較小時(shí),燃燒火焰前沿較為規(guī)則連續(xù),且發(fā)出較為強(qiáng)烈的白光,表明燃燒較為劇烈,而隨著煤塵粒徑的增大,燃燒火焰前沿趨向于離散不規(guī)則狀態(tài),發(fā)出紅黃色光,表明燃燒強(qiáng)度降低。(2)在預(yù)混燃燒火焰?zhèn)鞑ミ^(guò)程中,甲烷燃燒火焰放熱和粒徑大小影響熱電偶溫度上升時(shí)間,但主要是甲烷濃度決定熱電偶溫度上升時(shí)間;煤塵粒子燃燒決定火焰溫度最大值。在煤塵粒徑較大(54-74μm)時(shí),不同甲烷濃度的溫度上升時(shí)間差別很大;煤塵粒徑減小時(shí),甲烷濃度為3.7%和4.5%的溫度上升時(shí)間差別不大,但甲烷濃度為6.7%的溫度上升時(shí)間差別較大;6.7%的甲烷濃度的火焰溫度在預(yù)混物點(diǎn)燃很短的時(shí)間內(nèi)及開(kāi)始上升。隨煤塵粒徑增大,由于煤塵粒子的反應(yīng)速率和釋放的能量都降低,火焰溫度整體隨煤塵粒徑增大而減小,但中間略有波動(dòng)。(3)火焰?zhèn)鞑ニ俣仁怯杉淄楹兔悍酃餐瑳Q定的,其中甲烷對(duì)火焰?zhèn)鞑ニ俣扔绊戇h(yuǎn)遠(yuǎn)大于煤粉,而煤粉的火焰?zhèn)鞑ニ俣入S粒徑的增大而減小,因此,當(dāng)煤粉粒徑小于30-38.5μm時(shí),甲烷濃度對(duì)預(yù)混火焰的傳播起主導(dǎo)作用,6.7%甲烷濃度的預(yù)混火焰?zhèn)鞑ニ俣冗h(yuǎn)遠(yuǎn)大于3.7%和4.5%甲烷濃度;當(dāng)煤粉粒徑大于30-38.5μm時(shí),煤粉粒徑開(kāi)始影響預(yù)混火焰的傳播特性,導(dǎo)致火焰?zhèn)鞑ニ俣冉档。同時(shí),課題分別采用單步化學(xué)反應(yīng)模型(the single kinetic rate model)和擴(kuò)散-動(dòng)力控制燃燒模型(the kinetics/diffusion-limited rate model)重現(xiàn)煤塵-甲烷混合物的預(yù)混燃燒過(guò)程。通過(guò)分析燃燒管道中煤塵-甲烷混合物的預(yù)混燃燒的火焰圖像以及火焰溫度,并結(jié)合數(shù)值模擬方法,得出以下結(jié)論:(4)由煤塵-甲烷預(yù)混燃燒的數(shù)值模擬結(jié)果表明,預(yù)混火焰的前鋒位置以甲烷燃燒為主,而對(duì)于煤塵粒子,小部分熱量在火焰前鋒內(nèi)釋放,但在火焰前鋒過(guò)后,煤塵粒子依然持續(xù)燃燒較長(zhǎng)的時(shí)間,并釋放出它的大部分熱量。(5)根據(jù)煤塵-甲烷預(yù)混燃燒火焰鋒面處的溫度和化學(xué)反應(yīng)速率數(shù)值模擬云圖可得到預(yù)熱區(qū)厚度。在不同實(shí)驗(yàn)條件下煤塵-甲烷預(yù)混燃燒火焰的預(yù)熱區(qū)厚度在2~16mm范圍之間,且隨煤塵粒徑的增大,火焰?zhèn)鞑ニ俣冉档?熱量傳播時(shí)間增加,在相同的熱傳導(dǎo)速率條件下預(yù)熱區(qū)厚度增加。隨甲烷濃度增大,甲烷燃燒反應(yīng)速率增高、釋放熱量增多,傳遞給預(yù)熱區(qū)的熱量增多,使得預(yù)熱區(qū)厚度增大。
[Abstract]:The characteristics of the flame combustion experimental platform blends to build coal - methane pre, combined with high speed camera, data acquisition instrument and temperature sensors, the measured under different conditions of coal - methane premixed combustion flame shape map, propagation speed, the flame propagation characteristic parameters of temperature, and the analysis of coal - methane premixed combustion flame and the characteristics of coal dust particle size and concentration of methane on flame propagation characteristics of combustion of the mixture effect. Draw the following conclusions: (1) the burning flame shape and combustion intensity and concentration of methane and coal dust particle size is closely related to pre mixed coal methane. Methane concentration is 3.7%, the flame front is discrete and irregular, and when the concentration of methane increase of 4.5%, 6.7%, the flame front had a regular plane or paraboloid; when the dust particle size is small, the flame front is regular and continuous, the strong white hair The light indicates that the combustion is more severe, and with the increasing of the size of coal dust particle, the flame front tends to discrete and irregular state, a red and yellow light, indicating that the combustion intensity decreased. (2) in the premixed combustion flame propagation, flame heat and particle size effect of thermocouple temperature rise time of methane combustion, but mainly the methane concentration determines the thermocouple temperature rise time; coal dust combustion to determine the maximum flame temperature in coal dust. The larger particle size (54-74 m), different methane concentration temperature rise time difference; dust particle size decreases, methane concentration is 3.7% and 4.5% of the temperature rise time had little difference, but the methane concentration is 6.7% the temperature rise time difference; 6.7% of the methane concentration in the premixed flame temperature are ignited in a very short period of time and began to rise. With increasing diameter of coal dust particle, the reaction rate and the release of dust particles Energy is reduced, the temperature of the flame with the dust particle size decreases, but slight fluctuations. (3) the flame propagation velocity is determined by methane and coal, the effects of methane on flame propagation speed is far greater than that of pulverized coal, and the flame propagation velocity of pulverized coal with the particle size decreasing, therefore, when the coal the particle size is less than 30-38.5 m, the pre mixed flame propagation of methane concentration plays a dominant role, 6.7% concentration of methane premixed flame propagation speed is far greater than the 3.7% and 4.5% methane concentration; when the particle diameter is larger than 30-38.5 m, the propagation characteristics of pulverized coal particle size began to influence the premixed flame, the flame propagation speed reduced. At the same time, paper by a one-step chemical reaction model (the single kinetic rate model) and diffusion kinetic control combustion model (the kinetics/diffusion-limited rate model) to reproduce the coal - methane mixture premixed combustion Burning process. Through the analysis of the combustion pipe in coal - methane mixture premixed combustion flame image and flame temperature, and combining with numerical simulation, draw the following conclusions: (4) numerical simulation by coal - methane premixed combustion. The results show that the forward position of premixed flame in combustion of methane, and for coal dust particles small part of the heat release, the flame front, but after the dust particles in the flame front, still continue to burn for a longer time, and most of the heat release of it. (5) according to the flame temperature and chemical reaction rate can be obtained by numerical simulation of cloud thickness preheating zone combustion of blended coal methane in coal - pre. Under different experimental conditions of methane premixed combustion flame preheating zone thickness in the range of 2~16mm, and with the increase of the diameter of coal dust particle, the flame propagation speed is reduced, the heat transmission time increases, in the same heat conduction velocity The thickness of preheating area increased with the increase of methane concentration, and the rate of methane combustion increased, the amount of heat released increased, the heat transferred to the preheating area increased, and the thickness of preheating area increased.

【學(xué)位授予單位】:武漢理工大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2015
【分類(lèi)號(hào)】:TD714.5;O643.21

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