【摘要】：燒結(jié)工序作為鋼鐵工業(yè)產(chǎn)生SO2的主要來源，控制燒結(jié)煙氣中SO2的排放已經(jīng)成為我國環(huán)境保護和實現(xiàn)鋼鐵冶金行業(yè)持續(xù)發(fā)展的必然選擇。氨基濕法煙氣脫硫是目前應用較廣的燒結(jié)煙氣脫硫技術(shù)，但存在比較嚴重的“氨逃逸”現(xiàn)象，特別是對單塔氨法脫硫工藝來說，更為嚴重。本文根據(jù)某鋼鐵企業(yè)大型燒結(jié)機煙氣氨法脫硫塔運行情況，分析脫硫運行中存在問題，采用CFD技術(shù)對脫硫塔工藝運行參數(shù)及塔體幾何結(jié)構(gòu)變化對塔內(nèi)氣液流場的影響進行數(shù)值模擬研究，并通過與實際操作數(shù)據(jù)的對比對模擬結(jié)果加以驗證。 脫硫塔工藝運行參數(shù)優(yōu)化模擬結(jié)果表明：對于大型噴淋吸收塔宜選擇高位噴淋；綜合考慮塔內(nèi)液膜覆蓋效果、傳熱以及系統(tǒng)阻力情況宜選擇噴淋角度為90°或120°；煙氣入口流速的波動對塔內(nèi)流場的影響較大；在不考慮液滴蒸發(fā)的穩(wěn)態(tài)模擬系統(tǒng)下，煙氣入口溫度的變化對塔內(nèi)氣流分布均勻性與進出口壓損基本沒有影響，煙氣入口溫度越高，塔內(nèi)溫度降低的越快；提高液氣比可以促進傳熱、提高脫硫效率，但會降低塔內(nèi)流場的均勻性、增加阻力，在滿足環(huán)境保護要求的情況下，該脫硫系統(tǒng)液氣比控制在5~7L/m3較適宜。 脫硫塔幾何結(jié)構(gòu)優(yōu)化模擬結(jié)果表明：雙入口吸收塔相對于單入口吸收塔具有更好的氣流分布以及傳熱效果，同時，，切向雙入口可以避免直向雙入口時由于兩股煙氣對沖而造成煙氣局部過于密集的現(xiàn)象；對于大型脫硫塔，入口角度的改變對塔內(nèi)整個流場分布的均勻性及進出口壓損的影響不大，但是煙氣入口向下傾斜可以避免漿液池液位異常波動造成漿液進入入口煙道的情況，建議入口角度選擇10°左右為宜；煙氣入口區(qū)上方增設(shè)擋板可以有效隔擋噴淋漿液的進入以及有利于塔內(nèi)流場均布，檔板寬度宜取0.5m~1.0m，同時可以考慮設(shè)定一定傾角安置擋板；在入口段增設(shè)結(jié)構(gòu)簡單、操作簡便、呈階梯狀分布的導流板結(jié)構(gòu)可以改善塔內(nèi)氣流分布均勻性，促進傳質(zhì)傳熱；煙氣出入口同側(cè)且頂側(cè)出口方式下的塔內(nèi)流場相對合理。
[Abstract]:Sintering process is the main source of SO2 in iron and steel industry. Controlling the emission of SO2 in sintering flue gas has become an inevitable choice for environmental protection and sustainable development of iron and steel metallurgical industry in China. Amino wet flue gas desulfurization (WWFGD) is a widely used technology for flue gas desulfurization (FGD), but there is a serious "ammonia escape" phenomenon, especially for the single-tower ammonia desulfurization process. According to the operation of ammonia desulfurization tower in a large scale sintering machine of iron and steel enterprise, the problems existing in desulfurization operation are analyzed in this paper. The effects of operation parameters and geometric structure of the tower on the gas-liquid flow field in the tower were simulated by CFD technology, and the simulation results were verified by comparing with the actual operating data. The optimum simulation results of the operation parameters of the desulfurization tower show that the spray angle should be 90 擄or 120 擄for the large spray absorption tower, and the spray angle should be 90 擄or 120 擄for the comprehensive consideration of the effect of liquid film covering in the tower, the heat transfer and the resistance of the system. The fluctuation of flue gas inlet velocity has a great influence on the flow field in the tower, and the change of flue gas inlet temperature has no effect on the uniformity of air flow distribution and the pressure loss of inlet and outlet in the tower without considering the steady state simulation system of droplet evaporation. The higher the inlet temperature of flue gas is, the faster the temperature in the tower decreases. Increasing the liquid-gas ratio can promote heat transfer and increase the desulfurization efficiency, but it will reduce the uniformity of the flow field in the tower and increase the resistance, which can meet the requirements of environmental protection. It is suitable to control the ratio of liquid to gas in 5~7L/m3. The simulation results show that the double inlet absorber has better gas distribution and heat transfer effect than the single inlet absorber. Tangential double entrances can avoid the phenomenon of local concentration of smoke due to two streams of flue gas in the direct direction of double entrances; for large desulphurizing towers, The change of inlet angle has little effect on the uniformity of flow field distribution and the pressure loss of inlet and outlet in the tower, but the downward inclination of flue gas inlet can avoid the slurry entering the inlet flue caused by abnormal fluctuation of liquid level in the slurry pool. It is suggested that the inlet angle should be about 10 擄, that the addition of baffles above the flue gas inlet area can effectively block the entry of spray slurry and that the flow field in the tower can be evenly distributed, and that the width of the baffle should be 0.5 m or 1.0 m, at the same time, a certain inclination angle can be considered to set the baffle. The structure of the inlet section is simple and easy to operate. The flow field in the tower is relatively reasonable under the same side of the flue gas inlet and outlet and the top side exit mode, which can improve the uniformity of the air flow distribution in the tower and promote the mass transfer heat transfer.
【學位授予單位】：武漢科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X757

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