濕法FGD系統(tǒng)石灰漿池射流攪拌動力學(xué)研究
發(fā)布時間：2018-08-02 19:22
【摘要】：在現(xiàn)階段我國電力行業(yè)仍以燃煤為主燃料,隨之而來的SO2污染問題不容小覷。在我國,燃煤電場對于SO2的吸收以濕法煙氣脫硫?yàn)橹?代表方式為石灰石/石膏脫硫法。為了實(shí)現(xiàn)對SO2的充分吸收,就需要混合攪拌設(shè)備運(yùn)行良好,但是由于廣泛使用的側(cè)進(jìn)式攪拌系統(tǒng)造價高、易泄露且存在安全隱患等問題,故將旋轉(zhuǎn)射流系統(tǒng)引入濕法煙氣脫硫吸收系統(tǒng)中以克服以上缺點(diǎn)。本文在前人基礎(chǔ)上對旋轉(zhuǎn)射流系統(tǒng)加以完善并將其引入石灰漿池攪拌系統(tǒng),以蒲城600MW漿池建立幾何模型,分別在氣液及液固兩相工況下研究了旋轉(zhuǎn)射流器自轉(zhuǎn)角速度與射流出口速度對漿池流場的影響,并將兩相模擬結(jié)果與三相模擬結(jié)果加以比對,探究第三相的出現(xiàn)對流場所產(chǎn)生的影響。在氣液兩相工況中,氧化空氣分布的優(yōu)劣依賴于近壁面處的橫向分布速度與Z向速度的綜合作用。隨著自轉(zhuǎn)角速度的增加,氧化空氣的分布呈現(xiàn)出先趨于良好后趨于惡化的狀態(tài)；隨著射流出口速度的改變,氧化空氣分布趨于良好,但是當(dāng)速度高于50m/s之后,持續(xù)優(yōu)化現(xiàn)象并不十分明顯。在液固兩相工況中,隨著自轉(zhuǎn)角速度的增加,石灰石顆粒相濃度呈現(xiàn)出遞減趨勢,這是由于射流長度隨自轉(zhuǎn)角速度的增加而呈現(xiàn)出先增后減的趨勢,從而導(dǎo)致在近壁處的橫向分布速度呈現(xiàn)出先增后減的趨勢,進(jìn)而導(dǎo)致混合漿液與原純液相混合不足。隨著射流出口速度的增加,射流長度有所增加,從而使橫向分布速度增加,且由于總體流量的增大,漿池內(nèi)大循環(huán)加劇,從而使混合作用進(jìn)一步增強(qiáng),石灰石顆粒相濃度愈發(fā)接近射流出口處濃度。通過氣液兩相、液固兩相與氣液固三相工況進(jìn)行對比,結(jié)果表明氣液固三相工況中氧化空氣VOF高于氣液兩相工況,這是由于固相的出現(xiàn)使三相工況中的橫向分布速度趨于整體平緩,占優(yōu)勢體積的向下液流為氧化空氣的橫向分布提供了重要作用；液固兩相中石灰石顆粒相VOF高于三相工況,這是由于在中部向下液流流速基本相同的情況下,三相工況中近壁處混合液流橫向速度偏低而Z向速度偏高,導(dǎo)致未能與純液相充分混合,而導(dǎo)致三相工況下石灰石顆粒相濃度偏低。
[Abstract]:At the present stage, the power industry of our country still uses coal as the main fuel, and the SO2 pollution problem should not be underestimated. In China, wet flue gas desulfurization (FGD) is the main absorption of SO2 in coal-fired electric field, and limestone / gypsum desulfurization is the representative method. In order to fully absorb SO2, it is necessary for mixing equipment to run well, but the widely used side-feed mixing system is easy to leak and has some problems, such as high cost, easy leakage and hidden danger of safety, etc. Therefore, the rotary jet system is introduced into the wet flue gas desulfurization absorption system to overcome the above shortcomings. In this paper, the rotating jet system is improved and introduced into the lime slurry mixing system on the basis of predecessors, and the geometric model of Pucheng 600MW slurry pool is established. The effects of rotation angle velocity and jet exit velocity on the flow field of slurry tank were studied under the condition of gas-liquid and liquid-solid two-phase operation, and the results of two-phase simulation and three-phase simulation were compared. Explore the impact of the third phase of the presence of convection sites. In gas-liquid two-phase operation, the distribution of oxidized air depends on the combination of transverse velocity and Z-direction velocity near the wall. With the increase of rotation angular velocity, the distribution of oxidized air tends to be good first and then tends to deteriorate. With the change of jet velocity, the distribution of oxidized air tends to be good, but when the velocity is higher than 50m/s, the distribution of oxidized air tends to be good. The phenomenon of continuous optimization is not very obvious. In liquid-solid two-phase operation, the phase concentration of limestone particles decreases with the increase of rotation angular velocity, which is due to the increase of jet length with the increase of rotation angular velocity. Therefore, the transverse distribution velocity at the near wall shows a tendency of increasing first and then decreasing, and then leading to the insufficient mixing of mixed slurry and pure liquid phase. With the increase of the velocity of jet outlet, the length of jet increases, which makes the velocity of transverse distribution increase, and because of the increase of overall flow rate, the large circulation in the slurry pool intensifies, thus the mixing effect is further enhanced. The concentration of limestone particle phase is closer to the concentration of jet outlet. Through the comparison of gas-liquid two-phase, liquid-solid and gas-liquid-solid three-phase working conditions, the results show that the oxidized air VOF in gas-liquid-solid three-phase operation is higher than that in gas-liquid two-phase operation. This is because the appearance of solid phase makes the velocity of transverse distribution in three-phase operation tend to be smooth, and the dominant downward flow of liquid provides an important role for the transverse distribution of oxidized air, and the VOF of limestone particle phase in liquid-solid phase is higher than that in three-phase condition. This is due to the fact that the transverse velocity of the mixed liquid flow near the wall is lower and the Z-direction velocity is higher in the three-phase working condition when the downward flow velocity in the middle part is basically the same, which results in the failure to be fully mixed with the pure liquid phase. The phase concentration of limestone particles is low under three-phase working conditions.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X773
本文編號：2160476
[Abstract]:At the present stage, the power industry of our country still uses coal as the main fuel, and the SO2 pollution problem should not be underestimated. In China, wet flue gas desulfurization (FGD) is the main absorption of SO2 in coal-fired electric field, and limestone / gypsum desulfurization is the representative method. In order to fully absorb SO2, it is necessary for mixing equipment to run well, but the widely used side-feed mixing system is easy to leak and has some problems, such as high cost, easy leakage and hidden danger of safety, etc. Therefore, the rotary jet system is introduced into the wet flue gas desulfurization absorption system to overcome the above shortcomings. In this paper, the rotating jet system is improved and introduced into the lime slurry mixing system on the basis of predecessors, and the geometric model of Pucheng 600MW slurry pool is established. The effects of rotation angle velocity and jet exit velocity on the flow field of slurry tank were studied under the condition of gas-liquid and liquid-solid two-phase operation, and the results of two-phase simulation and three-phase simulation were compared. Explore the impact of the third phase of the presence of convection sites. In gas-liquid two-phase operation, the distribution of oxidized air depends on the combination of transverse velocity and Z-direction velocity near the wall. With the increase of rotation angular velocity, the distribution of oxidized air tends to be good first and then tends to deteriorate. With the change of jet velocity, the distribution of oxidized air tends to be good, but when the velocity is higher than 50m/s, the distribution of oxidized air tends to be good. The phenomenon of continuous optimization is not very obvious. In liquid-solid two-phase operation, the phase concentration of limestone particles decreases with the increase of rotation angular velocity, which is due to the increase of jet length with the increase of rotation angular velocity. Therefore, the transverse distribution velocity at the near wall shows a tendency of increasing first and then decreasing, and then leading to the insufficient mixing of mixed slurry and pure liquid phase. With the increase of the velocity of jet outlet, the length of jet increases, which makes the velocity of transverse distribution increase, and because of the increase of overall flow rate, the large circulation in the slurry pool intensifies, thus the mixing effect is further enhanced. The concentration of limestone particle phase is closer to the concentration of jet outlet. Through the comparison of gas-liquid two-phase, liquid-solid and gas-liquid-solid three-phase working conditions, the results show that the oxidized air VOF in gas-liquid-solid three-phase operation is higher than that in gas-liquid two-phase operation. This is because the appearance of solid phase makes the velocity of transverse distribution in three-phase operation tend to be smooth, and the dominant downward flow of liquid provides an important role for the transverse distribution of oxidized air, and the VOF of limestone particle phase in liquid-solid phase is higher than that in three-phase condition. This is due to the fact that the transverse velocity of the mixed liquid flow near the wall is lower and the Z-direction velocity is higher in the three-phase working condition when the downward flow velocity in the middle part is basically the same, which results in the failure to be fully mixed with the pure liquid phase. The phase concentration of limestone particles is low under three-phase working conditions.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X773
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