【作者】 卢珂；

【导师】 吴兆亮；

【作者基本信息】 河北工业大学 ， 化学工艺， 2015， 博士

【摘要】 泡沫分离技术是近些年发展比较快的分离技术,强化泡沫排液提高富集比是泡沫分离领域研究的永恒课题。塔壁在泡沫分离领域的研究,即塔壁对上升泡沫排液的影响及对泡沫分离效率的影响研究还未见报道。本文深入研究泡沫分离过程中塔壁排液行为,建立塔壁排液模型从深层次上揭示塔壁强化泡沫排液机理。开发了一种新型塔壁结构的泡沫分离塔,研究塔壁结构泡沫分离塔的分离性能,建立塔壁构件分离塔的富集比和回收率的预测模型。在此基础上考察了塔壁构件塔在处理实际染料废水和大豆蛋白废水的泡沫分离效果。实验结果表明塔壁与泡沫接触面积的增加强化了上升泡沫排液,降低了泡沫的出口持液量,加剧气泡聚并,提高了表面活性剂出口消泡液浓度。在低浓度、低气速、低的溶液粘度和大的分布器孔径下,塔壁强化排液效果更好。塔壁强化排液效果随着塔壁面积的增加而增加。依据通道理论和无因次排液模型建立了塔壁排液模型。模型分析表明在塔壁效应下,排液类型趋于节点排液是塔壁强化十二烷基硫酸钠(SDS)泡沫排液的主要原因;而塔壁强化牛血清白蛋白(BSA)泡沫排液是由壁面外通道数量的增加和排液类型趋于节点排液两方面因素造成的。塔壁构件泡沫分离塔对泡沫分离效率的影响研究表明,塔壁构件塔能够提高SDS和BSA的富集比,但同时回收率有所下降。在较小表面活性剂浓度、较小气速和较大分布器孔径下,塔壁构件更利于表面活性剂富集比的提高。p H偏离等电点时,塔壁构件提高BSA富集效果最好。塔壁构件位于泡沫相下部更有利于SDS泡沫排液,BSA则反之。随着塔壁构件长度和数量的增加,塔壁提高富集比能力增强。根据上升泡沫流体力学方程建立了连续泡沫分离过程中塔壁面积与富集比和回收率之间的函数关系式。模型计算结果与实验结果较为吻合。模型计算和实验结果表明排液速率的增加是富集比提高的主要原因。塔壁构件提高了SDS质量吸附流率和加速BSA气泡聚并也促使了各自富集比的提高,同时也是预测值和实验值存在偏差的主要原因。研究了塔壁构件泡沫分离塔对结晶紫模拟废水脱色、实际印染废水脱色和大豆蛋白废水处理的影响。实验结果表明,塔壁构件对实际物系的目标产物有很好的分离效果。在最佳操作条件下,塔壁构件实验塔的结晶紫富集比为16.5,是没有塔壁构件对照塔富集比的3.59倍。采用塔壁构件泡沫分离塔和二级泡沫分离技术以及Fenton试剂法处理实际印染废水,在最佳操作条件下,脱色率为86.5%,CODcr去除率80%,处理后的废水达到国家印染废水二级排放标准。采用塔壁构件分离塔以及二级泡沫分离技术处理大豆蛋白废水,在最佳操作条件下乳清蛋白富集比达到12.5,分别是垂直塔和斜塔富集比的1.65和1.47倍。综上所述,在泡沫分离过程中,泡沫分离塔的泡沫相塔壁面积的增加显著影响了泡沫排液过程,强化了泡沫排液,塔壁效应在泡沫分离过程中起着重要的作用。塔壁构件塔对于提高富集比是非常有效的,具有工业应用价值。更多还原

【Abstract】 Foam fractionation is a new fast-developing separation technology. It is an interesting topic in foam fractionation to enhance foam drainage and improve enrichment ratio. The wall effect on foam drainage and foam separation performances in foam separation has not been reported. In this paper, wall effect on foam drainage in foam fractionation was investigated. A wall drainage model was established for revealing the mechanism of wall effect in the enhancement of foam drainage. A foam fractionation column with wall internals was designed and its separation performance was investigated. Based on the hydrodynamics of rising foam, a model was established to determine foam separation performances using the column with wall internals. The column with wall internals was assessed for removing color from simulation crystal violet(CV) wastewater, real textile wastewater and recovering whey protein from whey wastewater.The results showed that the column wall had the performance of enhancing foam drainage. The increase of wall contact area in the foam phase significantly decreased the liquid holdup of the foam out of the column, intensified bubble coalescence and increased the surfactant concentration of the foam out of the column. The column wall had better performance in enhancing foam drainage at a lower surfactant concentration, air flow rate, liquid viscosity and a larger pore diameter of gas sparger. With increasing the wall internal number, the wall effect increased.The wall drainage model was obtained by the theory of Plateau channel and dimensionless drainage model. The theoretical model analysis showed that the increase of exterior Plateau channel number and transition from the channel-dominated drainage regime to node-dominate drainage regime contributed to wall effect in enhancing drainage of bovine serum albumin(BSA). The wall effect in enhancing drainage of sodium dodecyl sulfate(SDS) attributed to the transition of drainage regime.The effect of the wall internal on foam performance was investigated. The results showed that the column with wall internals had the higher enrichment ratio compared with the column without any wall internals. With decreasing surfactant concentration, volumetric gas velocity and increasing the pore diameter of the gas distributor, internal number, internal length, and pH deviating from the isoelectric point, the wall internal performance in improving enrichment ratio was intensified. Wall internals on the upper part of foam phase had the higher enrichment ratio than that on the lower part of foam phase for SDS. However, it was opposite for BSA.Based on the hydrodynamics of rising foam, a relationship between the wall area and the foam separation performance was obtained. The predicted enrichment values and recovery values were in good agreement with the experimental results. The theoretical model analysis showed that the increase of drainage velocity played a critical role in enhancing enrichment while bubble coalescence of BSA and a higher adsorption flux of SDS made slight contribution.The foam fractionation column with wall internals was assessed for removing color from simulation crystal violet wastewater, real textile wastewater and recovering whey protein from whey wastewater. The results showed that wall internals had good performance in the enrichment of target product in the actual systems. Under the suitable operations conditions, the enrichment ratio of CV was 16.5 by using the column with wall internals and it was 3.59 times higher than the column without wall internals. The two-stage foam fractionation technology with the column of wall effect and Fenton reagent were used in treatment of real dyeing wastewater. Under the suitable operations conditions, removal color efficiency reached 86.5% and removal CODcr efficiency reached 80%. The two-stage foam fractionation technology with the column of wall effect was used in the treatment of whey wastewater. Under the suitable operations conditions, the enrichment ratio of whey protein by using the column with wall internals was 12.5 and it was 1.65 times higher than the column without wall internals, 1.47 times higher than the inclined column.All above considered, the increase of wall area in foam phase had a significant influence on foam drainage in foam separation. Wall effect has play an important role in enhancing foam drainage and improving foam separation performaces. The column with wall internals can improve enrichment ratio effectively and has industrial application values.更多还原