本文關鍵詞： 風排瓦斯 可燃極限 絕熱燃燒溫度 狹縫 淬熄長度 阻火器　出處：《中國科學技術大學》2014年碩士論文　論文類型：學位論文

【摘要】：風排瓦斯減排近年來逐步受到重視,為保障減排系統(tǒng)安全運行、消除安全隱患,需要對甲烷-氧氣-氮氣-二氧化碳的混合氣體進行可燃極限研究,以及對混合氣體被點燃后的阻火進行研究。因此,本文主要針對這兩方面展開相關工作,為工業(yè)安全及阻火器設計提供參考。 對于可燃極限方面,本文首先采用數(shù)值計算方法進行可燃極限預測,然后根據(jù)預測結果設計實驗測量特定配比下的可燃極限。 基于化學平衡方法,采用ChemKin軟件求解不同配比下混合物的絕熱燃燒溫度。選取臨界溫度1450K作為混合氣體是否可燃的判別標準,研究了氮氣、氧化碳摻入對可燃極限的影響,并對甲烷與二氧化碳按特定比例混合的情況進行了可燃極限預測。 在7L爆炸容器中,用光電傳感器檢測距離點火源100mm處是否有火焰信號,如果3次重復實驗均未記錄到火焰信號則認為混合物不可燃,否則認為是可燃的。據(jù)此對瓦斯突出后與空氣混合的情況進行了可燃極限測量,并根據(jù)實驗情況進行修正,得到了甲烷與二氧化碳按不同比例混合時在空氣中的可燃極限。 風排瓦斯減排系統(tǒng)中點火發(fā)生后,為阻止火焰在管道內(nèi)傳播,需要安裝合適的阻火器。常用的波紋板型阻火器,其狹縫為三角形截面。不同截面形狀的狹縫之間有對應的換算關系。本文通過對矩形截面狹縫內(nèi)火焰?zhèn)鞑ゴ阆ǖ膶嶒炑芯恳约安煌孛嫘螤瞠M縫內(nèi)火焰淬熄的數(shù)值模擬,為阻火器的選擇及設計提供參考。 在矩形截面激波管內(nèi),安裝分布有不同寬度狹縫的裝置,火焰經(jīng)過加速段后進入狹縫�；鹧孢M入狹縫時的速度通過改變預混氣體中甲烷的含量進行調(diào)節(jié)。本文采用高速攝影記錄下火焰在狹縫內(nèi)的傳播和淬熄過程,最終得到不同入口火焰速度下的淬熄長度-狹縫寬度關系,并給出了相應的經(jīng)驗公式。 采用Fluent對火焰在狹縫內(nèi)的傳播和淬熄進行模擬,以1000K代表火焰陣面,作為火焰熄滅的臨界溫度,定性分析了不同入口火焰速度、不同狹縫寬度、不同截面形狀對淬熄長度的影響。 本文研究所得的瓦斯突出在空氣中的可燃極限范圍為工業(yè)安全提供了參考依據(jù)；得到的火焰在狹縫內(nèi)的淬熄長度與火焰速度、狹縫寬度的關系,可以指導阻火器選擇和設計,具有重要的應用價值。
[Abstract]:In order to ensure the safe operation of the emission reduction system and eliminate the hidden dangers, it is necessary to study the combustible limit of the mixture of methane, oxygen, nitrogen and carbon dioxide. Therefore, this paper mainly focuses on these two aspects of the relevant work to provide a reference for industrial safety and the design of fire arresters. For the flammable limit, this paper first uses the numerical calculation method to predict the flammable limit, and then designs experiments to measure the flammable limit under a specific ratio according to the predicted results. Based on the chemical equilibrium method, the adiabatic combustion temperature of the mixture was calculated by ChemKin software, and the critical temperature of 1450K was selected as the criterion for judging the flammability of the mixture. The influence of nitrogen and carbon oxide on the combustible limit was studied, and the combustible limit was predicted when methane and carbon dioxide were mixed in a specific proportion. In a 7L explosion vessel, the flame signal is detected by photoelectric sensor at 100mm distance from the ignition source. If the flame signal is not recorded in the three repeated experiments, the mixture is considered not combustible. Otherwise, it is considered combustible. Based on this, the combustible limit of the mixture of gas outburst and air is measured and modified according to the experimental results. The combustible limit of methane and carbon dioxide in the air was obtained when the methane and carbon dioxide were mixed in different proportions. In order to prevent the flame from spreading in the pipeline after the ignition occurs in the system of reducing gas emission from the wind, suitable fire arresters should be installed. The commonly used corrugated plate type fire arresters are needed. The slit is a triangular section. There is a corresponding conversion relationship between the slits with different cross-section shapes. In this paper, the experimental study of flame propagation quenching in the rectangular section slit and the number of flame quenching in the slit with different cross-section shapes are carried out. Value simulation. It provides reference for the selection and design of fire arresters. In the rectangular cross section shock tube, the device with different width slit is installed. The velocity of the flame entering the slit is adjusted by changing the methane content in the premixed gas. The flame propagation and quenching process in the slit is recorded by high-speed photography. Finally, the relationship between quenching length and slit width at different inlet flame velocities is obtained, and the corresponding empirical formulas are given. The flame propagation and quenching in the slit were simulated by Fluent. Using 1000K as the critical temperature of flame quenching, different inlet flame velocities were qualitatively analyzed. The influence of different slit width and section shape on quenching length. The flammable limit range of gas outburst in air obtained in this paper provides a reference for industrial safety. The relationship between the quenching length of flame in the slit and the flame velocity and slit width can guide the choice and design of the flame arrester and has important application value.
【學位授予單位】：中國科學技術大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TD712

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