發(fā)布時(shí)間：2018-02-14 02:58

  本文關(guān)鍵詞： 局部通風(fēng) 陣發(fā)性污染源 非穩(wěn)態(tài)過程 濃度分布 因素分析　出處：《西安建筑科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：在轉(zhuǎn)爐添加鋼水、渣車倒料和焦?fàn)t作業(yè)等工業(yè)生產(chǎn)過程中,往往存在不連續(xù)釋放污染物的污染源,也即陣發(fā)性污染源。由于污染源的間歇性釋放,其所產(chǎn)生污染物濃度分布是非穩(wěn)態(tài)的,且污染物的產(chǎn)生量也是不穩(wěn)定的,因此在實(shí)踐中不好控制。本文在數(shù)值模擬計(jì)算方法驗(yàn)證的基礎(chǔ)上,以一氧化二氮(N2O)為示蹤氣體,利用Fluent軟件研究了在局部排風(fēng)系統(tǒng)作用下該類污染源所產(chǎn)生非穩(wěn)態(tài)污染物濃度場的變化規(guī)律。首先,根據(jù)課題組實(shí)驗(yàn),通過對溫度場實(shí)驗(yàn)與模擬數(shù)據(jù)的誤差分析完成了穩(wěn)態(tài)模擬計(jì)算方法的驗(yàn)證,在此基礎(chǔ)上,通過對排風(fēng)系統(tǒng)(局部與全面通風(fēng))污染物濃度的誤差分析實(shí)現(xiàn)了非穩(wěn)態(tài)模擬計(jì)算方法的驗(yàn)證。其次,分析了非穩(wěn)態(tài)過程(該過程主要包括散發(fā)穩(wěn)定與衰減階段)初始流場、排風(fēng)系統(tǒng)與典型空間點(diǎn)(人員靜坐、站立時(shí)口鼻高度以及高空作業(yè)高度)濃度變化規(guī)律,以及散發(fā)穩(wěn)定階段局部排風(fēng)系統(tǒng)瞬時(shí)捕集效率,且對衰減階段排風(fēng)系統(tǒng)濃度變化進(jìn)行了公式擬合。最后,分析了污染源強(qiáng)度(污染物濃度和氣流速度)與局部排風(fēng)量對非穩(wěn)態(tài)過程排風(fēng)系統(tǒng)與典型空間點(diǎn)濃度變化的影響。本文工作得到如下主要結(jié)論:(1)在散發(fā)穩(wěn)定階段,排風(fēng)系統(tǒng)污染物濃度隨著時(shí)間的變化先增加后趨于穩(wěn)定,且全面通風(fēng)系統(tǒng)濃度曲線達(dá)到穩(wěn)定的時(shí)間滯后于局部排風(fēng)系統(tǒng)濃度曲線;在衰減階段,排風(fēng)系統(tǒng)污染物濃度呈負(fù)指數(shù)規(guī)律衰減。(2)在非穩(wěn)態(tài)過程中,污染源污染物濃度和氣流速度與局部排風(fēng)量單因素變化時(shí),排風(fēng)系統(tǒng)污染物濃度曲線變化規(guī)律一致。分析結(jié)果表明采用一氧化二氮(N2O)為示蹤氣體研究排風(fēng)罩捕集特性時(shí),示蹤氣體的濃度不宜過大;污染源氣流速度越大,散發(fā)穩(wěn)定階段濃度曲線變化越迅速,衰減階段初期變化越明顯,同一時(shí)刻濃度值越大,相較而言,污染源氣流速度對全面排風(fēng)系統(tǒng)濃度變化規(guī)律的影響較小;在某一時(shí)刻,排風(fēng)系統(tǒng)濃度隨著排風(fēng)量的增大而減小,且局部排風(fēng)量越大,濃度曲線達(dá)到穩(wěn)定狀態(tài)的時(shí)刻越早,衰減階段曲線變化越平緩。(3)在散發(fā)穩(wěn)定階段,污染源氣流速度越大,某一時(shí)刻空間點(diǎn)污染物濃度越大;隨著局部排風(fēng)量的增加,某一時(shí)刻空間點(diǎn)污染物濃度降低。在衰減階段,隨著時(shí)間的增加空間點(diǎn)濃度先穩(wěn)定后降低。
[Abstract]:In the process of industrial production, such as adding molten steel to converter, slag car feeding and coke oven operation, there is often a discontinuous pollutant source, that is, a paroxysmal pollution source. The concentration distribution of pollutants produced is unstable and the amount of pollutants produced is unstable, so it is difficult to control in practice. In this paper, based on the verification of numerical simulation method, nitrous oxide (N2O) is used as tracer gas. The variation of unsteady pollutant concentration field produced by this kind of pollution source under the action of local exhaust system is studied by using Fluent software. Based on the error analysis of temperature field experiment and simulation data, the steady-state simulation method is verified. Based on the error analysis of pollutant concentration in exhaust system (local and total ventilation), the unsteady simulation method is verified. Secondly, the initial flow field of the unsteady process (which mainly includes the stage of emission stability and attenuation) is analyzed. The variation law of concentration between exhaust system and typical space points (person sit-in, mouth and nose height and altitude when standing), as well as instantaneous capture efficiency of local exhaust system in the stage of distribution and stabilization, The variation of exhaust system concentration in attenuation stage is fitted by formula. Finally, The influence of pollution source intensity (pollutant concentration and airflow velocity) and local exhaust air volume on the concentration variation of unsteady process exhaust air system and typical space points is analyzed. The main conclusions in this paper are as follows: 1) at the stage of distribution and stabilization. The concentration of pollutants in exhaust system increases first with time and then becomes stable, and the time of concentration curve of overall ventilation system lags behind that of local ventilation system. The concentration of pollutants in exhaust air system attenuates in a negative exponential law. (2) in the process of unsteady state, the concentration of pollutants, the velocity of air flow and the amount of local exhaust air are changed by single factor. The analysis results show that the concentration of tracer gas should not be too large when using nitrous oxide N _ 2O) as tracer gas to study the capture characteristics of exhaust hood, and the air velocity of pollution source is higher. The faster the concentration curve changes in the stable phase of emission, the more obvious the change in the initial stage of attenuation is, and the greater the concentration at the same time. Compared with the change of concentration in the overall exhaust system, the air velocity of the pollution source has less influence on the variation of the concentration of the total exhaust system at a certain time. The concentration of exhaust system decreases with the increase of exhaust air volume, and the larger the local exhaust volume is, the earlier the concentration curve reaches the stable state, and the more gentle the decay phase curve is, the more the air velocity of pollution source increases at the stage of emission stabilization. The higher the concentration of pollutants is at a certain time, the lower the concentration of pollutants is at a certain time with the increase of local exhaust volume. At the attenuation stage, the concentration of space point first stabilizes and then decreases with the increase of time.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X51;TU834

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 蔡浩;控制污染物擴(kuò)散的應(yīng)急通風(fēng)關(guān)鍵問題研究[D];同濟(jì)大學(xué);2006年

相關(guān)碩士學(xué)位論文 前3條

1 劉金;室內(nèi)空氣品質(zhì)與流場關(guān)系的研究[D];南京理工大學(xué);2003年

2 張瑋;高大空間室內(nèi)污染物控制的數(shù)值模擬與研究[D];華北電力大學(xué)（河北）;2009年

3 朱奮飛;帶回風(fēng)系統(tǒng)中室內(nèi)污染物動態(tài)濃度分布規(guī)律研究[D];清華大學(xué);2009年

，

本文編號：1509717