本文關(guān)鍵詞：濕法煙氣脫硫除霧效率和流場優(yōu)化的數(shù)值模擬研究　出處：《東南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 折流板除霧器 除霧效率 濕式電除塵器 流場優(yōu)化 數(shù)值模擬

【摘要】：環(huán)境形勢的日益嚴(yán)峻和環(huán)保要求的進(jìn)一步提高,使粉塵、酸霧等大氣污染物的治理日益受到人們的重視。除霧器作為燃煤電廠煙氣除霧的主要設(shè)備,其除霧性能好壞決定除霧后煙氣能否達(dá)到排放標(biāo)準(zhǔn)。為了研究提高除塵、除霧效率的有效方法,本文對燃煤電廠濕法脫硫系統(tǒng)中廣泛使用的折流板除霧器和近年發(fā)展起來的應(yīng)用在濕法脫硫塔后,在脫除PM2.5、硫酸霧、微細(xì)粉塵、汞金屬等方面取得了良好效果的濕式電除(霧)塵器進(jìn)行了數(shù)值模擬研究。分析了不同參數(shù)對折流板除霧器除霧效率的影響；研究了提高濕式電除塵器內(nèi)部流場均勻性的流場調(diào)節(jié)的常規(guī)方法和新方法。本文的主要研究內(nèi)容包括以下幾個方面：(1)針對目前燃煤電廠濕法脫硫系統(tǒng)中廣泛使用的折流板除霧器,本文利用歐拉—格朗日法對濕法脫硫折流板除霧器內(nèi)氣液兩相流動建立數(shù)學(xué)模型。參考已有實驗研究對本文所建立模型進(jìn)行驗證。通過模擬計算得到除霧器葉片間距、板型、流速對不同粒徑霧滴的分級除霧效率和總除霧效率的影響,得到不同粒徑霧滴的運動軌跡和捕集規(guī)律：流速在2-7 m·S-1,板間距在20,26,38mm范圍的梯形和三角形葉片除霧器,粒徑小于16μm的霧滴去除效率隨流速增加呈現(xiàn)不規(guī)律的波動,隨著板間距的增加而下降的趨勢不明顯,幾乎不受葉片形狀變化的影響；粒徑大于16μm的霧滴去除效率隨流速增加而增大,隨著板間距增加顯著下降；在板間距為38mm時,梯形板除霧效率大于三角形板,在板間距較小的情況下,兩種板型的性能相差不大；流速小于3 m·s1時,粒徑小于20μm霧滴的去除對氣流均勻性要求較高,氣流擾動增強利于小霧滴的碰撞聚并；流速高于3 m·S-1時,氣流擾動增強增加了小霧滴運動的隨機性,不利于小霧滴的碰撞聚并。(2)針對濕式電除塵器在工業(yè)應(yīng)用中存在流場分布不均導(dǎo)致的除塵、除霧效率降低等問題,本文以某電廠濕式電除塵器改造項目為案例,對濕式電除塵流場進(jìn)行了數(shù)值模擬計算,將模擬結(jié)果與現(xiàn)場實驗測試結(jié)果對比,驗證了模擬的準(zhǔn)確性。通過流場分析得到除塵器入口流量分配不均和電場區(qū)流場分布不均的原因,利用流場調(diào)節(jié)的常規(guī)方法,通過設(shè)置導(dǎo)流板,氣流分布板等措施,對入口煙道,進(jìn)氣喇叭等結(jié)構(gòu)進(jìn)行改造,使得入口流量分配均勻,電極迎風(fēng)面流場分布得到改善。分析得出：為使入口流量均勻分配,應(yīng)綜合采用以下措施：增加入口煙道寬度、在入口煙道轉(zhuǎn)彎處增設(shè)圓弧導(dǎo)流板、在聯(lián)箱內(nèi)增加斜導(dǎo)流板；圓弧導(dǎo)流板能對煙道內(nèi)的氣流流動起到良好的組織作用,進(jìn)氣喇叭的錐度不能過小,否則會引起氣流對濕式電除塵器內(nèi)部電場區(qū)的直接沖刷,且增加系統(tǒng)壓降；進(jìn)氣喇叭內(nèi)設(shè)置角度沿錐度較小一側(cè)傾斜的導(dǎo)流斜板,將氣流導(dǎo)向錐度較小一側(cè)區(qū)域,可改善由于喇叭原始結(jié)構(gòu)的缺陷造成的喇叭出口流場分布不均的問題；常規(guī)的流場調(diào)節(jié)方法雖然能在一定程度上改善氣流分布,降低流速峰值,其調(diào)節(jié)過程需要反復(fù)調(diào)試,且調(diào)節(jié)后的流場仍然無法滿足一些濕式電除塵器對流場均勻性的高要求。(3)基于數(shù)值模擬方法研究探討了一種調(diào)節(jié)流場均勻性的新方法,利用橫向和縱向隔板相互交錯在喇叭口內(nèi)形成梯形導(dǎo)流結(jié)構(gòu),根據(jù)喇叭出口截面某區(qū)域流量與對應(yīng)的喇叭入口該區(qū)域面積的關(guān)系,能夠分別在兩個方向?qū)瓤诔隹诮孛媪鲌鲞M(jìn)行調(diào)節(jié)。與常規(guī)方法相比能夠有效降低流速偏差,使電極迎風(fēng)面流速在2～3m/s的區(qū)域面積占78%,流速偏差達(dá)到0.19,提高目標(biāo)截面的流速均勻性；為了避免兩個方向的流量調(diào)節(jié)相互干擾,喇叭口內(nèi)的橫向隔板與縱向隔板的高度應(yīng)保留一定的高度差,差值根據(jù)喇叭尺寸確定；橫向與縱向隔板數(shù)量或梯形蜂巢結(jié)構(gòu)導(dǎo)流柵格的數(shù)目的設(shè)定,是根據(jù)對流場均勻性的要求來確定的,其數(shù)目越多,可實現(xiàn)的均勻性越高。
[Abstract]:The increasingly severe environmental situation and environmental requirements to further improve the management of dust, mist and other atmospheric pollutants has attracted more and more attention. As a coal-fired power plant flue gas demister main equipment in addition to fog, the fog removal performance determines whether in flue gas can reach the discharge standard after the fog. In order to study the effective method to raise the dust, mist in this paper, efficiency, widely used in coal-fired power plant wet FGD system in baffle demister and developed in recent years in the application of wet desulfurization tower, the removal of PM2.5, sulfuric acid mist, dust, and other aspects of mercury has achieved good results in wet electric dust collector (FOG) is simulated study on the analysis of the different parameters. Besides the effect of baffle mist mist removal efficiency; to study the wet electrical precipitator internal flow field of the conventional method of uniform flow field adjustment and new methods to study in this paper. The content includes the following aspects: (1) according to the current widely used in coal-fired power plant wet FGD system in baffle demister, the wet desulfurization baffle in gas-liquid two-phase flow in the mist, the mathematical model is established. Using the Euler Lagrange method experimental study on reference has been established in this paper to verify the model. Demister blade spacing plate, by simulation, velocity of different size droplet classification demisting efficiency and total efficiency of the demister, the motion trace of different particle size and droplet trapping Law: velocity in 2-7 m S-1, the distance between the trapezoidal plate in the range of 20,26,38mm and triangular blade mist eliminator the diameter of less than 16 m, the droplet removal efficiency decreased with the increase of flow rate in irregular fluctuations decreased with increasing trend of the plate spacing is not obvious, hardly affected by leaf shape change; particle size larger than 16 m fog Droplet removal efficiency decreased with the increase of flow rate increases, with the increase of plate spacing decreased significantly; the plate spacing is 38mm, trapezoidal plate demisting efficiency is greater than the triangular plate, the plate spacing is smaller, the performance of two plate types had little difference; flow rate is less than 3 m - S1, the diameter of less than 20 m droplet the removal of the airflow uniformity higher, air turbulence enhanced collision to small droplet coalescence; flow rate is higher than 3 m - S-1, the increase of airflow disturbance random droplet movement, is not conducive to the collision of small droplet coalescence. (2) for removal of wet electric dust collector has the flow field distribution in industry application in the poor, in addition to the fog and low efficiency, in a power plant wet electrical precipitator retrofit project as a case of wet ESP flow field is simulated, the simulation results and experimental test results verified the simulation of quasi Sure. The flow field analysis by flow distribution in ESP entrance and uneven electric field causes the uneven distribution of the flow field, the conventional method using the flow field in the control by setting the guide plate, the airflow distribution board and other measures of entrance flue of intake horn structure, the entrance flow distribution, flow field distribution of the windward side electrode improved. Analysis shows that: in order to make the entrance flow uniform distribution, should adopt the following measures: increase the flue entrance width, adding arc guide plate in the corner entrance flue, increasing inclined guide plate in headers; arc guide plate can flow in the flue gas flow on the organizations have played a good role, air horn does not taper too small, otherwise it will cause the flow of direct erosion of wet electric dust collector of internal electric field area, and increase the system pressure drop; angle along a small inlet horn side inclined taper Guide board, one side of the air guide taper smaller area can be improved due to the defects of original horn horn outlet flow field structure of the problem of uneven distribution; conventional flow field regulating method although can improve the flow distribution in a certain extent, reduce the peak velocity, the adjusting process requires repeated debugging, and still can not be adjusted flow meet some of the wet electrical precipitator flow field uniformity requirements. (3) numerical simulation method to study a new method for adjusting the flow uniformity based on the horizontal and vertical baffles are mutually staggered to form trapezoidal diversion structure on the bell mouth, according to the relationship between horn outlet section a regional flow and the corresponding speaker entrance the area of the region, can be respectively in the two directions of the bell flow at the exit section. The adjustment can effectively reduce the velocity deviation compared with the conventional method, the electrode of attack The wind velocity in the area of 2 ~ 3m/s accounted for 78%, flow rate deviation reached 0.19, the goal of improving the uniformity of the velocity in cross section; in order to avoid the two direction regulating the flow of mutual interference, the transverse clapboard and a longitudinal baffle the bell mouth height should retain a certain height difference, the difference according to the number of horizontal and horn size determination; the number of longitudinal baffle or trapezoidal honeycomb structure diversion grid set, according to the flow field uniformity requirements to determine, the number of the more uniformity can be achieved more.

【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X773

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