本文選題：洗滌冷卻室　切入點：霧化　出處：《華東理工大學》2015年博士論文　論文類型：學位論文

【摘要】：本文以多噴嘴氣流床氣化的關鍵設備洗滌冷卻室為研究背景,對復合型洗滌冷卻室內(nèi)的流體流動特性及溫度分布進行了研究�？疾炝藲馑�、液體流速、霧化器數(shù)量等參數(shù)對床層內(nèi)壓降、液滴夾帶、霧化液滴粒徑及液滴濃度的影響。采用數(shù)值模擬方法建立了洗滌冷卻室內(nèi)部流場及溫度場數(shù)學模型,分析了復合型洗滌冷卻室的工程應用可行性。(1)依據(jù)工業(yè)數(shù)據(jù),對洗滌冷卻管內(nèi)高溫合成氣的溫度分布進行數(shù)值模擬研究。模擬結果表明在洗滌冷卻管入口處0-2m段降溫最快,3-6m段降溫較平緩,說明氣液間熱交換接近平衡。根據(jù)模擬結果,提出縮短洗滌冷卻管長度及增加噴霧冷卻霧化器的改進方案,以避免洗滌冷卻管出現(xiàn)堵塞等工程問題。并搭建了冷態(tài)實驗裝置,研究了氣速,液體流速等對床層內(nèi)壓降影響。研究結果表明：干塔狀態(tài)下,由于床層阻力影響較小,整個床層內(nèi)部的壓力分布較為均勻；濕塔狀態(tài)下,霧化液滴與氣體的錯流對床層壓降起到擾動作用,壓降比干塔時提高約50%。(2)對復合型洗滌冷卻室氣體出口處的氣相液滴夾帶過程進行了研究�？疾炝藲怏w速度、液體流速、降膜冷卻水流量、霧化器空間位置等因素對液滴夾帶分率的影響。研究表明：液滴夾帶分率隨床層表觀氣速、液體流速的增加均呈上升趨勢,而其在徑向上的分布相對較為均勻；液體流速增大能降低霧化液滴粒徑梯度,粒徑較小的液滴易被氣流夾帶,導致出口液滴夾帶分率有一定提高,但液滴在隨氣流運動過程中,小液滴會出現(xiàn)聚并,形成較大粒徑液滴而脫離氣流,因此液滴夾帶分率增量較小。霧化器數(shù)量增加加劇霧化液滴聚并,沉降液滴數(shù)量增多。霧化器數(shù)量從對稱兩個設置變?yōu)橥驅ΨQ四個時,液滴夾帶量降低約40%。液滴夾帶量受表觀氣速及液體流速影響較大,通過實驗數(shù)據(jù)獲得了液滴夾帶分率與條件參數(shù)的經(jīng)驗關聯(lián)式：(3)利用Malvern Spraytec測試儀對洗滌冷卻室內(nèi)霧化液滴的粒徑分布進行了測定。結果表明：液體流速增大促使液滴粒徑減�。粴饬魉俣仍黾哟偈瓜礈炖鋮s室氣體出口液滴粒徑增大。霧化器數(shù)量越多,液滴間劇烈作用導致液滴粒徑梯度變大�？拷F化器徑向r/R=0.3位置霧化液滴粒徑較大,洗滌冷卻室中心位置處較小。液滴在洗滌冷卻室軸向位置的分散主要依靠氣流的攜帶,隨著軸向距離的增大,氣體能攜帶的液滴粒徑逐漸變小,在洗滌冷卻室氣體出口處液滴能被氣流攜帶的臨界粒徑約為80～150μm。(4)采用等速取樣法,研究了洗滌冷卻室內(nèi)氣液兩相摻混過程中,霧化液滴濃度在床層內(nèi)分布。獲得了在不同霧化器數(shù)量及氣液流速條件下,洗滌冷卻室內(nèi)的霧化液滴濃度分布圖。研究發(fā)現(xiàn)液體流速的增大使流體錯流誘導效應增強,促進液滴向床層空間的快速擴散；而床層氣速的增大,則能增大氣液相所形成漩渦的能量,從而促進液滴向軸向擴散運動。四霧化器條件下同一空間位置的液滴濃度較兩霧化器增大將近一倍,但霧化液滴在洗滌冷卻室內(nèi)的分布更加均勻,即增加霧化器數(shù)量能消除床層內(nèi)死區(qū)。依據(jù)實驗結果獲得了洗滌冷卻室徑向位置霧化液滴濃度經(jīng)驗式：(5)采用數(shù)值模擬方法建立了復合型洗滌冷卻室內(nèi)傳質傳熱三維數(shù)值模型,研究了洗滌冷卻室內(nèi)的多相流動、傳質和傳熱等行為。模擬結果表明,單霧化器噴霧范圍有限,洗滌冷卻室溫度分布不均勻,降溫效果不佳。液體流速的增加使得霧化液滴粒徑減小,有利于熱量傳遞。在相同熱交換量下,隨著液體流速增大,氣體溫度降幅相應提高。對置噴霧冷卻,洗滌冷卻室上部空間內(nèi)霧化液滴的數(shù)量較多,保證了冷卻效果�？拷F化器軸向h/H=0.72處合成氣溫度最低。洗滌冷卻室底部,液相分率增高,霧化液滴換熱冷卻效果降低。流場內(nèi)氣液兩相錯流作用,提高了液相的蒸發(fā)效率,強化了傳熱和傳質的效果。
[Abstract]:In this paper the key device of scrubbing cooling chamber of multi nozzle entrained flow gasification as the research background, the characteristics of fluid flow and temperature distribution of the composite quench chamber is studied. The influences of the gas flow rate, liquid flow rate, the pressure drop of the bed number parameters of atomizer, droplet entrainment, effect of atomization droplet size and liquid droplet concentration. By using the method of scrubbing cooling chamber internal flow field and temperature field mathematical model numerical simulation, analyzed the feasibility of engineering application of composite scrubbing cooling chamber. (1) based on industrial data, numerical simulation of the temperature distribution of the scrubbing cooling tube in high temperature synthesis gas. The simulation results show that in the scrubbing cooling tube at the entrance 0-2m cooling is the fastest, 3-6M cooling slowly, the gas-liquid heat exchange near equilibrium. According to the simulation results, put forward to shorten the scrubbing cooling pipe length and increase improvement of spray cooling atomizer The case, in order to avoid scrubbing cooling pipe blockage and other engineering problems. And built a cold state experimental device, the influence of gas velocity, liquid flow rate on the bed pressure drop. The results show that under the condition of the tower, due to the small effect of bed resistance, the whole bed internal pressure distribution is uniform in the wet tower; under the condition of liquid droplets and gas flow on the bed pressure drop to disturbance, increased by about 50%. when the pressure drop Biganta (2) drop entrainment process exports to composite scrubbing cooling chamber gas gas liquid was studied. The effects of the gas velocity, liquid flow velocity, cooling water flow. Radial position factors on the rate of droplet entrainment. Research shows that the droplet entrainment rate increases with the superficial gas velocity, liquid flow rate increased, but the distribution is relatively uniform in the radial direction; the liquid flow rate increase can reduce the fog The droplet size of the gradient, the smaller size of droplets easily by air entrainment, leading to the export droplet entrainment rate increased, but with the droplets in the air flow process, droplet coalescence will appear, the formation of large size droplets from the air, so the droplet entrainment rate increment a small increase in the number of atomizer. Increasing droplet coalescence and sedimentation, droplets increased in number. The number from the atomizer two symmetric set to four symmetric, droplet entrainment decreased about 40%. droplet entrainment by the superficial gas velocity and liquid velocity is affected by the experimental data obtained experience association type droplet entrainment rate parameters and conditions: (3) the scrubbing cooling chamber of atomized droplet size distributions were determined using the Malvern Spraytec tester. The results showed that the liquid velocity increases the particle size decreases; flow velocity increase gas scrubbing cooling chamber The outlet of the body of the droplet size increases. The atomizer amount is more, interaction between droplets leads to the droplet size gradient becomes larger. Near the radial position of r/R=0.3 droplet in spray atomizer of large particle size at the center position of the washing cooling chamber is smaller. Droplet in the scrubbing cooling chamber axial position dispersion mainly depends on the airflow carrying, with the increase of the axial distance, can carry the gas droplet size becomes smaller, the scrubbing cooling chamber gas outlet of liquid droplet can be air carries the critical particle size is about 80~150 M. (4) by isokinetic sampling method of scrubbing cooling chamber of gas-liquid two-phase mixing process, droplet concentration in bed layer distribution. Obtained in different number of nozzles and liquid velocities under the condition of droplet concentration distribution in scrubbing cooling chamber. The study found that increasing liquid flow rate of the fluid cross flow induced effect enhancement, promote the drop to the empty bed Fast diffusion between the bed; and the gas velocity increases, can increase the gas-liquid phase form a vortex of energy, so as to promote the droplet axial diffusion motion. The droplet concentration four atomizer conditions the same spatial position compared to the two increase of atomizer nearly doubled, but the atomized droplets in the washing cooling indoor distribution uniform, increase the number of nozzles can eliminate the bed dead. According to the experimental results obtained the scrubbing cooling chamber radial position of the atomized droplet concentration formula: (5) using the method to establish the value model of the composite quench chamber of mass and heat transfer in 3D numerical simulation of scrubbing cooling chamber of multiphase flow, heat transfer and mass transfer such behavior. The simulation results show that the single sprayer limited, scrubbing cooling chamber temperature distribution is not uniform. The cooling effect is poor. The increase of liquid velocity makes the droplet size decreased, favorable for heat transfer Delivery. In the same amount of heat exchange, along with the liquid flow rate increases, the gas temperature drop increased. Opposite spray cooling, a large number of droplets in the upper space of scrubbing cooling chamber, the cooling effect is ensured. Near the axial h/H=0.72 synthesis gas atomizer. The lowest temperature washing cooling chamber bottom, liquid chromatography rate increased. The droplet heat cooling effect is reduced. The role of gas-liquid two-phase flow in the wrong, improve the evaporation efficiency of liquid phase, strengthen the effect of heat and mass transfer.

【學位授予單位】：華東理工大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ051.5

【引證文獻】

相關碩士學位論文 前1條

1 管蕾;激冷式氣流床粉煤氣化爐模擬研究[D];華東理工大學;2016年

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本文編號：1590177