基于颗粒界面修饰的悬浮液粘度调控方法

发布时间：2019-01-07 07:25

【摘要】：本文以水煤浆气化技术为背景,为制得高浓度低粘度的水煤浆,研究了颗粒表面性质及添加剂对颗粒悬浮液粘度的影响。针对日益严重的水污染问题,研究了工业废水中的常见成分对制浆的影响。论文的主要研究内容及结论如下:系统研究了第二液体对颗粒悬浮液粘度的影响。发现随第二液体含量的增加,悬浮液的粘度和屈服应力表现出先减小后增加再减小的趋势。利用荧光染料标记第二液体,在激光共聚焦显微镜下观察悬浮液的微观结构。发现随第二液体浓度的增加,悬浮液出现三种状态,即分散态、团簇态和胞囊状态。三种状态对应了粘度的非单调趋势。低阶煤的孔隙发达,制备浆体时水会进入煤颗粒的孔隙中形成内水,从而引起颗粒间的自由水减少,煤浆粘度增高,难以制备高浓度水煤浆。实验发现干燥的煤颗粒从空气中吸潮,可使浆体粘度大幅下降。通过浆体的可压缩性实验发现吸潮的水分将少量气体密封到颗粒的孔隙中,使制浆过程中颗粒吸入的水分减少。基于实验和表征,提出了封孔效应的理论,即低阶煤颗粒具有大量极性官能团,预吸潮的水分通过氢键作用于孔口内壁,如同"瓶塞"将颗粒的孔口密封,有效阻止了来自溶剂的水分向煤颗粒孔隙内扩散。从空气中预吸潮的水分还可提高第二液体的作用,使得浆体粘度进一步减小,为低阶煤制浆提供了新的思路。研究了工业废水中的常见成分——小分子含氧有机物,对水煤浆粘度的影响。发现添加小分子有机物会导致对水煤浆的粘度的增加。借助激光共聚焦显微镜、红外光谱和接触角测量等表征手段。发现在浆体中,煤颗粒的疏水性表面吸附了小分子含氧有机物,亲水性增强,从而导致水化膜增厚,自由水减少。因此,含小分子有机物的有机废水不利于水煤浆制备。表面活性剂广泛存在于生活和工业污水中,为研究其对水煤浆的影响,实验以空心玻璃微珠悬浮液为模型,研究微量表面活性剂对悬浮液的影响。发现阴离子表面活性剂可使空心玻璃微珠悬浮液从粘性流体变为膏状,流动性急剧恶化。通过对悬浮液微观结构表征发现,微量的阴离子表面活性剂降低界面张力,产生微小气泡。颗粒聚集在气泡周围,在气泡间膜内形成空间阻碍,并减缓排液,有利于气泡的稳定。微小气泡作为第三相,在悬浮液中发挥了不优先润湿颗粒的第二液体的作用,并使悬浮液处于团簇状态,粘度和屈服应力显著增加。此膏状悬浮液属可逆的亚稳定体系,长时间静置后膏状结构因排液而被破坏。
[Abstract]:Based on coal water slurry gasification technology, the effects of particle surface properties and additives on the viscosity of coal water slurry with high concentration and low viscosity were studied in this paper. The influence of common components in industrial wastewater on pulping was studied in view of the increasingly serious water pollution problem. The main contents and conclusions of this paper are as follows: the effect of the second liquid on the viscosity of the suspension is studied systematically. It is found that the viscosity and yield stress of the suspension decrease first and then decrease with the increase of the second liquid content. The second liquid was labeled with fluorescent dye and the microstructure of the suspension was observed under confocal laser microscope. It is found that with the increase of the second liquid concentration, there are three states in the suspension, that is, the dispersed state, the cluster state and the cytosolic state. The three states correspond to the non-monotone trend of viscosity. Due to the developed pores of low-rank coal, water will enter the pores of coal particles to form internal water, which leads to the decrease of free water between particles and the increase of viscosity of coal slurry, which makes it difficult to prepare high concentration coal water slurry. It is found that dry coal particles absorb moisture from air and decrease the viscosity of slurry. Through the compressibility experiment of the slurry, it is found that the moisture absorbed by moisture absorbs a small amount of gas to the pores of the particles, which reduces the moisture absorbed by the particles during the pulping process. Based on the experiments and characterization, the theory of sealing effect is put forward, that is, the low-rank coal particles have a large number of polar functional groups, and the pre-moisture absorbed water acts on the inner wall of the orifice through hydrogen bonding, which is similar to the "bottle plug" which seals the pore opening of the particle. It effectively prevents the diffusion of water from the solvent into the pores of coal particles. The moisture preabsorbed from the air can also increase the effect of the second liquid and further reduce the viscosity of the slurry, which provides a new way of thinking for the low rank coal pulping. The influence of small molecule oxygen-containing organic compounds on the viscosity of coal water slurry was studied. It is found that the addition of small molecular organic compounds can increase the viscosity of coal water slurry. By means of laser confocal microscope, infrared spectrum and contact angle measurement, etc. It is found that the hydrophobic surface of coal particles adsorbs small molecular oxygen-containing organic compounds in the slurry, and the hydrophilicity increases, which results in the thickening of the hydration film and the decrease of free water. Therefore, organic wastewater containing small molecular organic compounds is unfavorable to the preparation of coal water slurry. Surfactant widely exists in domestic and industrial sewage. In order to study the influence of surfactant on coal water slurry, the influence of micro surfactant on suspension was studied by using hollow glass microbeads suspension as a model. It is found that anionic surfactants can change the suspension of hollow glass beads from viscous fluid to paste, and the fluidity deteriorates rapidly. The microstructures of suspensions were characterized by microamounts of anionic surfactants, which reduced the interfacial tension and produced micro bubbles. The accumulation of particles around the bubble, the formation of space in the interbubble membrane, and slow down the flow of liquid, which is conducive to the stability of the bubble. As the third phase, the micro bubble plays the role of the second liquid which does not give priority to wetting particles, and makes the suspension in the cluster state, and the viscosity and yield stress increase significantly. The paste suspension is a reversible substable system, and the paste structure is destroyed after long statics.
【学位授予单位】：华东理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ536

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