连续反应系统中陶瓷膜过滤特性研究

陶瓷膜组件具有较高的分离效率且稳定性好,本文是将多相反应器与陶瓷膜过滤组件组成连续装置,以期实现液固分离和操作的连续化,以空气-水-活性炭三相为研究介质,对其过滤特性进行研究,结果表明:陶瓷膜组件能够确保在较长时间内过滤的稳定性;过滤通量受过滤压力的影响较大,过滤压力越大过滤通量越大;过滤通量随着循环流量的增大而增大。     

陶瓷膜过滤受污NHD脱碳液的改进工艺研究

通过添加配料对受污NHD脱碳液中固体杂质进行改性处理,然后采用陶瓷膜对添加配料后的受污NHD脱碳液进行净化处理,研究了配料种类、添加量及跨膜压差等因素对过滤性能的影响,确定了添加配料后陶瓷膜过滤受污NHD脱碳液的最佳操作条件.试验结果表明:在室温、操作压力为0.10MPa的条件下,选用配料a、其添加质量分数为0.2%时,对受污NHD脱碳液进行净化处理,处理后受污NHD脱碳液的固体杂质去除率可达94.5%,且NHD脱碳液的吸收性能未变.     

陶瓷膜过滤技术的应用

简要叙述了GL陶瓷膜过滤的工艺流程、工作原理及应用效果。     

气升式陶瓷膜过滤装置处理油田含聚采出水

采用新型的气升式陶瓷膜过滤系统处理油田含聚采出水,通过气液两相流替代单一的液相流动,降低了陶瓷膜处理油田含聚采出水过程的能耗,系统考察了曝气孔大小、曝气量和跨膜压差对膜渗透通量的影响。结果表明,采用孔径为微米级的曝气头曝气使高压气体在多通道膜管内的分布更为均匀,进而有效抑制膜污染和浓差极化,延缓通量衰减。当曝气孔径为1 μm时,渗透通量达到最大,且曝气量从300 L·h^-1增加到600 L·h^-1时,通量显著增加。此外,跨膜压差对膜的渗透通量影响显著,当跨膜压差为0.4 MPa时,渗透通量最佳。陶瓷膜处理油田采出水的出水水质各方面指标数据较为稳定,达到5.1.1回注水标准。最后,计算讨论了气升式陶瓷膜过滤装置的吨水能耗。     

臭氧对陶瓷膜过滤特性的影响

为了提高陶瓷膜的通量和过滤效果,采用臭氧-陶瓷膜组合工艺对水厂源水进行试验,研究了臭氧对陶瓷膜通量和过滤效果的影响。试验发现:在源水中投加臭氧可使陶瓷膜通量有一定程度的增加,且膜孔径越大其增加幅度越明显。对于10 nm陶瓷膜,臭氧投加量为1 mg.L-1时通量最大,增加约25%～30%;对于100 nm陶瓷膜,臭氧投加量5 mg.L-1时通量最大,增加约40～55%。随着臭氧投加量的增大和运行时间的延长,10 nm和100 nm陶瓷膜的出水浊度基本不受影响,出水浊度均稳定,约0.07～0.10 NTU。投加臭氧对10 nm、100 nm陶瓷膜去除源水中UV254均有一定促进作用,10 nm陶瓷膜对UV254的去除率可增加约9%～18%,100 nm陶瓷膜对UV254的去除率可增加约3%～7%。     

气液两相流强化陶瓷膜过滤煤炭矿井水的研究

采用气液两相流工艺强化陶瓷膜过滤矿井水。研究了曝气与不爆气、曝气流量以及曝气头孔径大小对陶瓷膜通量的影响。结果表明,曝气对陶瓷膜通量影响较大,采用2 mm曝气孔、在曝气量为1.5~2.5 m3/h条件下的陶瓷膜运行效果比采用1.2 mm曝气孔、曝气量为0.8~1.1 m3/h的运行效果好。并在此基础上,考察了浓缩倍数对陶瓷膜通量的影响。     

盐水中沉淀物对气升式陶瓷膜过滤性能的影响

采用化学沉淀法进行盐水精制是氯碱工业的关键过程之一.今采用陶瓷膜脱除盐水中的沉淀物,考察了气升条件下盐水中化学沉淀物(CaCO3、BaSO4、Mg(OH)2)对陶瓷膜过滤过程的影响.结果表明,曝气对三种体系均可显著提高膜的渗透通量,含CaCO3盐水体系的膜通量与含BaSO4体系相当,是含Mg(OH)2体系膜通量的1.5倍;当曝气量大于300 L?h?1时,进一步增大曝气量对含CaCO3、BaSO4体系的盐水渗透通量影响不大,但可使含Mg(OH)2体系盐水渗透通量提高50%以上;跨膜压差与通量基本呈线性增大关系,跨膜压差对CaCO3、BaSO4体系通量的影响大于对Mg(OH)2体系的影响;固含量增大,由于体系黏度显著增大,使三种体系的膜通量均呈下降趋势,含Mg(OH)2体系的通量下降最大.对盐水中沉淀物的分析结果表明,方解石相的CaCO3颗粒分散均匀,粒径为16.08μm,表面电势为?16.5 mV;重晶石相的BaSO4颗粒粒径在2.18μm左右,表面电势为?33 mV;而无定形的Mg(OH)2颗粒粒径分布宽,平均粒径1.59μm,表面电势为?18 mV.由于粒径与荷电性的双重作用,使得CaCO3、BaSO4体系膜过滤阻力相近,小于Mg(OH)2体系的膜过滤阻力;钙镁离子共沉淀中,随着钙离子量的增大,膜过滤通量增大.     

微也民陶瓷膜过滤的阻塞状况及再生方法

通过对平板陶恣膜为过滤介质的动态旋叶压滤机的微波实验，研究了阻塞系数Ｋ的影响；对陶瓷膜的再生效率进行了探讨，提出了有效的再生方法；显示了用瓷膜作为动态旋叶压滤机过滤介质的优越性。     

气升式陶瓷膜过滤过程的气液两相流模拟

采用VOF双流体模型对19通道气升式陶瓷膜过滤装置进行气液两相流的流体动力学模拟,研究了曝气孔直径和曝气量对气升式陶瓷膜过滤装置的气含率、环流液速、膜面剪切力及膜管内湍流强度的影响,模拟结果与实验结果的误差在5%~10%之间。结果表明,气升管与降液管的气含率都随曝气量增大而增大,随曝气孔直径减小而增大;环流液速、膜面剪切力及膜管内的湍流强度都随曝气量增大先增大,当曝气量达到400L·h^-1时其增大趋势变缓。通过实验和模拟比较了3种不同孔径的曝气头,环流液速与曝气孔的直径关系不大,仅与曝气量相关,但曝气孔直径越小,其膜面剪切力越大,越有利于过滤过程的进行。     

陶瓷膜过滤技术在煤制乙二醇工艺中的应用

介绍了陶瓷膜过滤技术在煤制乙二醇工艺中应用,通过试验和分析,采用微孔陶瓷膜过滤器较好的解决了煤制乙二醇过程中微细颗粒精密过滤技术难题,提升煤制乙二醇成品的品质。     

气升式陶瓷膜装置过滤钛硅分子筛悬浮液

为克服膜污染,提高膜通量,文章将曝气引入到陶瓷膜过滤过程中,计算了曝气量对液相循环流速、气含率以及膜面剪切力的影响。采用气升式陶瓷膜过滤装置,以平均孔径为200 nm的ZrO2陶瓷膜为分离介质,考察了固含量(质量浓度)、曝气量、跨膜压差对钛硅分子筛悬浮液固液分离性能的影响。结果表明:曝气量增大,液相循环流速和气含率随之增大;曝气量在416—2 333 mL/min内,气液二相流流型为弹状流,气弹区膜面剪切力是液弹区的3—10倍。陶瓷膜对钛硅分子筛的截留率为100%;当固含量为1%时,曝气量由100 mL/min增大至850 mL/min,膜稳定通量增大了33%,进一步增大曝气量,通量开始下降。膜的稳定通量随着固含量的增大而降低。当曝气量为850 mL/min,固含量为1%时,跨膜压差由0.1 MPa增大至0.2 MPa,稳定通量降低了41%,但进一步增大跨膜压差到0.3 MPa时,稳定通量又表现出增大趋势。对膜过滤阻力的计算分析结果表明:曝气作用能减轻浓差极化,但不能消除滤饼与膜孔堵塞污染。     

Experiment and calculation of filtration processes in an external-loop airlift ceramic membrane bioreactor

Air sparging is recognized as an effective way to increase permeate flux in membrane filtration processes. The application of air sparging with an external-loop airlift ceramic membrane bioreactor was studied at different gas flow rates, biomass concentrations and suction pressures. A 180% increase in permeate flux was obtained while filtering a 2 g/L activated sludge wastewater suspension with the airlift cross-flow operation for U_g=0.21 m/s. The mechanism of flux enhancement in the case of slug flow in tubular membrane was discussed. The region near the gas slug was divided into three different zones: falling film zone, wake zone and remaining liquid slug zone. Air sparging significantly lowered cake thickness and consequently cake resistances for the wake region and the falling film region. A novel model combining hydrodynamic of gas-liquid two-phase flow and cake resistance was developed to simulate the process. The model was validated with experimental data with an error of 8.3%.     

Viscoelastic behavior of ceramic suspensions with carrageenan

Aqueous gelcasting of ceramic suspensions with carrageenan is one of the novel ceramic shaping techniques that have received considerable attention during the last few years. The ability of carrageenans to form cold-setting reversible gels in aqueous media is responsible for the body formation step. In this work the rheology and viscoelastic behavior of these systems is studied. Zirconia (TZ-3YE) suspensions with a solids loading of 67 wt.% (i.e. approximately 25 vol.%) and three different carrageenan concentrations (0.7, 1.0 and 1.3 wt.%, related to the free water content in the suspension) were prepared. The temperature dependence of the dynamic storage and loss moduli is determined by oscillatory shear rheometry. The concentration dependence of melting and cooling cycles (ranges 50–63 and 29–37 °C, respectively) is considered and analyzed. The results are interpreted in terms of linear viscoelasticity and the gelation step is discussed in relation to the mechanism of body formation.     

Filtration process cost in submerged anaerobic membrane bioreactors (AnMBRs) for urban wastewater treatment

The objective of this study was to evaluate the effect of the main factors affecting the cost of the filtration process in submerged anaerobic membrane bioreactors (AnMBRs) for urban wastewater (UWW) treatment. Experimental data for CAPEX/OPEX calculations was obtained in an AnMBR system featuring industrial-scale hollow-fiber (HF) membranes. Results showed that operating at J₂₀ slightly higher than the critical flux results in minimum CAPEX/OPEX. The minimum filtration process cost ranged from €0.03 to €0.12 per m³, mainly depending on SGD_m (from 0.05 to 0.3 m³·m^?2·h^?1) and MLSS (from 5 to 25 g·L^?1). The optimal SGD_m resulted in approx. 0.1 m³·m^?2·h^?1.     

Effect of length of branched-chain of PAA-g-MPEO on dispersion of CaCO3 aqueous suspensions

The viscosity of CaCO₃/poly(acrylic acid) grafted methoxyl poly(ethylene oxide) (PAA-g-MPEO) aqueous suspensions was influenced by length of the branched-chain and content of PAA-g-MPEO. The viscosity of CaCO₃/PAA-g-MPEO suspensions first decreased and then increased with increasing length of branched-chain of PAA-g-MPEO at the same PAA-g-MPEO content. The viscosity of CaCO₃ suspensions containing PAA-g-MPEO with short branched-chain ([`(M)]<sub>n</sub> \bar{M}_{n}  = 200 g/mol and 600 g/mol) decreased with increasing the PAA-g-MPEO content. However, the viscosity of CaCO<sub>3</sub> suspensions containing PAA-g-MPEO with long branched-chain ([`(M)]_n \bar{M}_{n}  = 1500 g/mol) increased with increasing the PAA-g-MPEO content. The size distribution of CaCO₃ particles in CaCO₃ suspensions containing PAA-g-MPEO with the short branched-chain became narrower and the average size decreased with increasing length of the branched-chain. This is due to the steric hindrance of branched-chain of the PAA-g-MPEO adsorbing on surface of the CaCO₃ particles increased with increasing length of the branched-chain. The size distribution of CaCO₃ particles in CaCO₃ suspensions containing PAA-g-MPEO with the long branched-chain had two regions, and the average size increased compared with that of CaCO₃ particles in the CaCO₃ suspensions containing PAA-g-MPEO with the short branched-chain. This is due to the flocculation of fractional CaCO₃ particles induced by “tangle” between the long branched-chain of PAA-g-MPEO adsorbing on surface of CaCO₃ particles.