【作者】 何春红；

【导师】 刘家祺；

【作者基本信息】 天津大学 ， 化学工艺， 2005， 博士

【摘要】 炼油厂在向贮油罐、油槽车、油罐车装卸油品时产生大量挥发性有机蒸汽（VOCs）,必须加以回收利用。目前所采用的有机蒸汽的回收方法都有各自不足之处,采用膜法分离回收VOCs具有高效、节能、操作简单和不造成二次污染等优点。本文以回收油品装卸过程产生的有机蒸汽为研究内容,对中空纤维复合膜、气体膜分离技术和数学模型进行了研究。本文选取了4种中空纤维基膜、3种硅橡胶涂层材料,采用浸渍涂敷法制备了多种中空复合膜。考察了硅橡胶浓度、催化剂用量、交联剂用量等因素对复合膜分离性能的影响,得到了最佳制膜配方和制膜条件。采用热处理的方法对基膜进行了改性,结果证明基膜的物理结构对复合膜的分离性能有影响,并且得到不同基膜的最佳热处理条件。实验结果表明以经过393.2K、12min热处理的PVDF为基膜和RTV-107为涂层制备的复合膜分离效果较好。采用扫描电镜、红外光谱和XPS等表征方法对硅橡胶涂层、基膜以及中空纤维复合膜的结构和性能等进行了剖析。考察了原料气的压力、原料气流速、原料气浓度、操作温度和透过气压力等工艺操作参数对RTV-107/PVDF复合膜气体分离性能的影响,得到最佳工艺条件下正己烷、正庚烷的渗透速率分别为1.4×10^-7、1.5×10^-7 mol/（m²·s·Pa） ,正己烷/氮气、正庚烷/氮气的分离因子分别为90、474。制备了填充型复合膜,考察了不同填充剂类型、用量对膜性能的影响。填充剂的加入提高了膜对正庚烷的选择性,增大了正庚烷的渗透速率,降低了氮气的渗透速率,同时适量的填充剂可明显增大膜机械强度。研究了基膜形态结构对分离性能的影响,建立了改进的DGM模型,提出基膜的双结构模型,考察了基膜致密层有效孔隙率ε/τ、努森扩散系数K₀以及涂层厚度等对复合膜传质阻力的影响。对采用RTV-107/PVDF自制中空纤维膜组件的有机蒸气回收工艺过程,建立了逆流设计型数学模型。研究了原料气压力、透过气压力、原料气处理量、透余气浓度等不同操作条件和分离要求对膜面积的影响。并对中空纤维复合膜有机蒸气回收的气体膜分离中试装置进行了初步设计,提出了中试装置设想和实验流程。更多还原

【Abstract】 Volatile organic compounds （VOCs） produce a large amount of waste emissions when the processing plants load, unload the oil onto the tanks, fuel tankers and oil tankers. The recovery of Volatile organic compounds has been under scrutiny. However, most existing techniques for organic vapor emissions control have so far proved to be unsatisfactory. Membrane technology which has high efficiency, economy, simple operation and no secondary pollution is expected to provide an alternative to the recovery of VOCs. In this study, the preparation of hollow fiber composite membranes, gas membrane separation and the mathematic model of mass transfer were investigated.Firstly, the hollow fiber composite membranes were prepared by dip-coating method with 4 kinds of hollow fibers as the substrate layer, and 3 kinds of silicone rubbers as the coating layer material. The effects of some factors, which include the silicone rubber, catalyst and cross-linker concentration of composite membrane on gas separation performance were discussed. The heating treatment was applied to enhance the separation performance of some membrane, which shows that the physical structure of base membranes has effect on the separation performance of composite membrane. The suitable conditions for heating treatment and preparing the composite membrane were found, and the composite membrane of RTV-107/PVDF got the best performance with the base membrane heating treatment under 393.2K and 12 minute. The structure and properties of silicone rubber, base membrane and hollow fiber composite membranes were analyzed by SEM, IR and XPS methods.Secondly, the effects of feed pressure, feed flow rate, feed concentration, permeate pressure and operating temperature on the gas separation performance also investigated. The permeabilities of n-hexane and n-heptane were 1.4×10^-7、1.5×10^-7 mol/（m²·s·Pa） respectively and the separation factors of n-hexane/nitrogen and n-heptane/nitrogen could be 90、474 respectively.The third, filled-type composite membrane was prepared. The effect of species and amount of filling agents on the gas separation performance was also discussed. The permeabilitiy of n-heptane and the separation factor of n-heptane/nitrogen were improved when the composite membrane was filled with filling agents. Otherwise, the mechanical performance of silicone rubber filled with suitable fillings was increased. Then a two-layer model based on DGM model was presented to describe the influence of the porous support layer of the composite membrane on the gas separation performance. The effect of the base membrane structure parameters such as effective porosityε/τ, morphological parameter K₀ and the thickness of coating on gas separation properties were also discussed.Lastly, for RTV-107/PVDF hollow fiber membrane, a countercurrent-flow design model was established which can describe VOCs/N₂ separation process. This mathematical model was based on the gas linear flow rate and could be applied in more gas separation processes, which was better than the model in most references. The simulation using the model is performed by changing the operating conditions and the optimum operating factors and the required membrane area are investigated. Then the design proposal of this technique for industrial application was brought forward.更多还原