泡沫法团聚细微颗粒物的实验研究及数值模拟

发布时间：2018-03-02 06:02

  本文关键词： 泡沫法 团聚剂 细微颗粒物 团聚机理 数值模拟　出处：《青岛大学》2017年硕士论文　论文类型：学位论文

【摘要】：泡沫法团聚细微颗粒物属于化学方法团聚细微颗粒物的一种,主要是利用各种化学试剂通过化学反应或化学键作用促使细颗粒凝聚变为大颗粒团。泡沫法不同于雾化液滴法,主要是通过雾化喷嘴使得添加发泡剂与稳泡剂的团聚液,雾化成大量气泡和液滴,形成的泡沫增大了团聚液与含尘气流接触的比表面积。随着粉尘细微颗粒物不断碰撞气泡并粘附在气泡表面,导致气泡破碎,进而团聚细微颗粒物。首先进行粘附细微颗粒物所需气泡条件的研究,对气泡直径与团聚颗粒物的能力进行估算。通过CCD拍摄精细雾化喷嘴喷出的团聚液泡沫流动过程,利用MATLAB处理图片,得出雾化气泡直径和密度(截面上数量)大小。结果表明,采用同一喷嘴,发泡剂(十二烷基苯磺酸钠)和稳泡剂(椰油酸二乙醇酰胺)的添加增强了团聚液雾化液滴形成气泡,增加了雾化泡沫的数量;以PAM(非离子型聚丙烯酰胺)为团聚剂的溶液形成的气泡直径偏小,且雾化后液滴和气泡的数量密度大,粒径主要分布在小于200μm范围;XTG(黄原胶)团聚液气泡直径偏大,CMC(羧甲基纤维素钠)团聚液气泡直径介于两者之间。0.2%CMC团聚液气泡直径均匀,气泡和液滴数量多;在轴向距喷嘴25cm处,气泡破碎和聚合趋于稳定;喷嘴直径0.5mm时,气泡直径大多分布在100~300μm粒径范围,符合理论计算的团聚PM2.5的气泡条件;随着溶液温度的升高,直径在0~300μm内的气泡颗粒数量明显增大。其次,通过自行设计建立的实验系统进行实验研究,分析泡沫团聚剂种类、浓度、温度,喷淋层数及除雾器层数等因素对细微颗粒物脱除效率的影响。实验发现泡沫团聚剂能有效的将烟气中细微颗粒物粘附团聚形成颗粒团。在PAM、CMC和XTG三种团聚剂中,XTG的团聚作用最为明显;经0.1%XTG团聚液喷淋团聚后的排气中经孔板除雾器颗粒物浓度降低为10.6 mg/m3;XTG团聚液在80℃下,对细微颗粒物团聚后脱除效率最高,排烟颗粒物浓度为9.4 mg/m3;增加喷淋层数可以有效的减少团聚除雾后尾气中颗粒物浓度;增加孔板除雾器数量对团聚效果影响不大。最后,结合实验中的进出口参数,利用Fluent软件中的PBM模型进行数值模拟研究。仅对喷淋段与顺流段进行模拟。参照实验结果来调整模型及其参数,获得符合实验工况的流动模拟,从而分析得到泡沫法团聚细微颗粒物的机理;随泡液比的增加,颗粒物团聚作用更为明显,气泡对团聚起主要的作用;团聚液粘度增大对颗粒物团聚起促进作用,但过大会影响雾化从而影响团聚。本研究的泡沫团聚细微颗粒物的机理是满足所需气泡条件下,细微颗粒物不断粘附浸没在气泡表面,当团聚了颗粒物的气泡上重力与表面张力间平衡破坏后,气泡破碎,细微颗粒物聚合为大颗粒团,固相粒径增大,利于后部的除雾器或除尘器脱除颗粒物。
[Abstract]:Foam agglomeration of fine particles belongs to one of the chemical methods of agglomeration of fine particles. It mainly uses a variety of chemical reagents to make fine particles agglomerate into large particles by chemical reaction or chemical bond action. Foam method is different from atomization liquid drop method. Mainly through atomizing nozzles, the agglomerates with foaming agent and foam stabilizer are added to atomize a large number of bubbles and droplets. The resulting foam increases the specific surface area of the agglomerate in contact with the dust-containing airflow. As fine particles of dust continuously collide with the bubble and adhere to the surface of the bubble, the bubble breaks up. Then the fine particles were agglomerated. Firstly, the bubble conditions needed to adhere to the fine particles were studied, and the bubble diameter and the ability of agglomeration particles were estimated. The foam flow process of the agglomerates ejected from fine atomization nozzles was photographed by CCD. The diameter and density of atomized bubbles (number of sections) are obtained by MATLAB. The results show that the same nozzle is used. The addition of foaming agent (sodium 12 alkylbenzenesulfonate) and foaming stabilizer (coconut oil diethanolamide) enhanced the atomizing liquid droplets of agglomerates to form bubbles and increased the number of atomized foam. The bubble diameter formed by the solution of PAM (non-ionic polyacrylamide) as agglomeration agent is small, and the number density of droplets and bubbles after atomization is large. The diameter of the bubble in XTG agglomeration is larger than 200 渭 m. The diameter of CMC (sodium carboxymethyl cellulose) agglomeration is between the two. The diameter of the bubble is uniform, the number of bubbles and droplets is large, and the diameter of bubbles and droplets is more than 25cm from the nozzle, and the diameter of the bubble is larger than 200 渭 m, and the diameter of CMC (sodium carboxymethyl cellulose) agglomeration is between the two. When the diameter of the nozzle is 0.5 mm, the bubble diameter is mostly distributed in the diameter range of 100 渭 m to 300 渭 m, which accords with the theoretical calculation of the bubble condition of agglomeration PM2.5, and increases with the increase of solution temperature. The number of bubble particles in the diameter of 0 ~ 300 渭 m is obviously increased. Secondly, through the experimental system designed by ourselves, the types, concentration and temperature of foam agglomerators are analyzed. The effect of spray layer number and mist layer number on the removal efficiency of fine particles was studied. It was found that foam agglomeration agent could effectively agglomerate fine particles in flue gas to form particles. The agglomeration effect was the most obvious. After spray agglomeration with 0.1% XTG agglomeration solution, the concentration of particulate matter decreased to 10.6 mg / m ~ (3) XTG agglomerate in the exhaust gas from the porous plate precipitator. At 80 鈩，

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