Economic comparison of transverse and longitudinal flow hollow fiber membrane modules for reverse osmosis and ultrafiltration

The presently used hollow fiber membrane modules consist of a bundle of fibers in a cylindrical polymer or metal shell parallel to the shell axis. The feed solution flows either through the lumen or at the outside parallel to the fibers. This paper compares the performance of these modules with a new transverse flow module where the hollow fibers are positioned perpendicularly to the flow direction. For both types of modules the product costs are calculated for desalination by reverse osmosis and Dextran concentration by ultrafiltration. These calculations are based on literature data. The main conclusion is that the application of the tr‘ansverse flow module is only attractive if the permeation resistance is mainly determined by the hydrodynamics (ultrafiltration) and not attractive if the membrane permeability is the main resistance (reverse osmosis).     

Aciplex—F4111与Aciplex—F4112膜主要指标的对比分析

从三友集团冀东化工公司离子膜烧碱的生产实践出发,把日本旭化成公司生产的Aciplex—F4111与Adplex—F4112膜的主要性能绘制成图并进行了对比分析,为同行业选择膜时提供参考。     

Nafion全氟离子交换膜与Aciplex-F离子交换膜的比较

对Ｎａｆｉｏｎ全氟离子交换膜及Ａｃｉｐｌｅｘ－Ｆ离子交换膜的性能包括操作条件、预处理,及商务保证条款进行比较,系统地介绍了该两种离子膜的相同点与不同点,为氯碱厂选择采购离子膜产品提供依据。     

凯膜及陶瓷膜技术应用的比较

介绍了凯膜技术、陶瓷膜技术在一次盐水精制中的应用情况及陶瓷膜的发展前景。     

凯膜及陶瓷膜技术应用比较

介绍了凯膜技术、陶瓷膜技术在一次盐水精制中的应用以及陶瓷膜的发展前景。     

内压式超滤膜与外压式超滤膜的工程应用分析比较

根据内压式超滤膜和外压式超滤膜组件在冶金污水回用处理工程中的实际应用,从运行参数、出水水质、清洗周期等方面对两者进行了综合分析比较,同时分析了超滤膜污染的成因、工艺优化采取的措施。结果表明,外压式超滤膜跨膜压差的稳定性和产水透过率优于内压式超滤膜,2种膜的产水水质接近,外压式超滤膜的化学清洗周期是内压式超滤膜的3倍,外压式超滤膜更适用于大流量冶金污水反渗透脱盐的预处理。     

Analysis of hollow fiber reverse osmosis membrane module of axial flow type

Several analyses of hollow fiber reverse osmosis (RO) modules in which permeate water flows from the outer to the inner side of the membrane have been attempted over the past 20 years. In our previous work, an FCP (Friction Concentration Polarization) model showed good agreement with a wide range of actual performance data of a hollow fiber RO membrane module of radial flow type. In this work, this analytical model was applied to axial flow type hollow fiber modules. The performance of the axial flow type module with high packing density of hollow fibers was analyzed, taking into consideration the axial concentration profile in the module. It was confirmed that this model showed good agreement with experimental data for an axial flow type RO membrane module. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

改善膜表面流动状态防治膜污染技术的研究进展

介绍了各种改善膜表面流动状态防治膜污染技术的原理和研究进展,对这些技术的优缺点进行了分析比较,并阐述了相关膜污染防治技术的应用前景和研究方向。     

Cement particle flocculation and breakage monitoring under Couette flow

Freshly mixed concrete is a suspension of cement and aggregate particles dispersed in water. To secure the desired quality of freshly mixed concrete, understanding its rheological behavior, which depends on its flow rate, is necessary. A number of chemical and physical factors influence the rheology of freshly mixed concrete, and the flocculation of cement particles is thought to cause thixotropy and shear thinning. This study proposes a rheometer coupled with a laser backscattering device, which allows us to simultaneously measure the viscosity and the size distribution of cement clusters in cement paste suspension. The laser backscattering instrument measures the cluster size distribution and monitors its growth or breakdown, while the parallel-plate rheometer measures its rheological properties. As a result, the change of cement grains was continuously observed with the change of shear stress under specific strain rates of 1 s^− 1, 10 s^− 1, and 100 s^− 1.     

High throughput membrane emulsification using a single-pass annular flow crossflow membrane

Membrane emulsification has the potential to revolutionize the energy-efficient production of uniform emulsions and dispersions, relevant to diverse fields from pharmaceutical active ingredient controlled release particles to Fast Moving Consumer Goods. A novel highly robust single-pass continuous phase crossflow system has been developed providing dispersed phase concentrations up to 40% vol/vol and dispersed phase fluxes up to 5,730 L m⁻² hr⁻¹, from a single 100 mm long membrane tube. Extensive results of two oil-in-water systems (vegetable oil and PolyCaproLactone dissolved in DiChloroMethane) and one water-in-oil system (sodium silicate solution) are reported, using hydrophilic and hydrophobic membranes respectively. Mathematical models are validated enabling comprehensive engineering analysis of processes including predicted droplet size, membrane pressure drops, and energy requirement for dispersion production. Surfactant depletion, pore utilization, and droplet interaction at the membrane surface were investigated to provide a comprehensive analysis of the capabilities of novel annular-flow membrane emulsification for high throughput emulsion generation.     

污水流量监测中流量计的选择

由于污水具有流量变化大、含有杂质、具有导电性和腐蚀性的特点,导致其流量计的选择比较复杂。从被测对象、流量计性能、安装条件、使用环境、经济成本等方面,对电磁流量计、超声波流量计、V锥流量计进行了对比分析,为污水流量监测过程中流量计的合理选用提供参考。     

Microfluidic modeling and simulation of flow in membrane microreactors

We study the development of a mathematical model that describes isothermal microfluidic steady flow in a membrane microreactor, i.e., a silicon microreactor that houses a permeable membrane in one wall. The model employs the Navier-Stokes equation with appropriate boundary conditions for fluid permeation through the membrane and velocity slip at the walls to account for high Knudsen number. The model equations are solved analytically using finite Fourier transforms. The model solution is used to evaluate the effect of fluid permeation through the membrane and the Knudsen number on the velocity profile and pressure drop. For the simplified cases of no permeation and/or no slip, the derived solution is in excellent agreement with published experimental and theoretical results available in the literature. The utility of the model is illustrated by applying the results to a membrane microseparator used to separate hydrogen from the other effluents in a microreformer.     

旋转流管式微滤膜的流场探测及分离性能研究

利用水力旋流器原理采用切向进料使膜器环隙产生旋转流,为探明旋转流场的特征,应用PIV(粒子图像测速技术)测试系统进行了实测,结果表明环隙中存在起强化过滤作用的类Taylor涡。在此基础上对旋转流场进行了过滤分离实验,以探讨旋转流场中的进料方式、悬浮液质量分数和操作压力对过滤的影响。研究发现由于存在旋转流和二次涡流的剪切强化作用使得在相同工况下旋转流过滤的稳定通量达到普通轴向流的4—10倍,这表明旋转流过滤是一种有效的膜过滤强化方法之一,由此为进一步探讨旋转流膜过滤强化机理,减少浓差极化和膜污染提供实验依据。     

Hybrid membrane and conventional processes comparison for isoamyl acetate production

Four process alternatives for the production of isoamyl acetate, by the liquid phase esterification of acetic acid with isoamyl alcohol, were evaluated by simulation in terms of product purity, energy integration and economics. The analysis involves a transition from conventional (two structures that use acetic acid or alcohol in excess) to hybrid membrane process (two distillation–pervaporation hybrid systems). Acetate recovery is identified as a crucial factor to minimize energy costs in all considered processes. For conventional processes, the amount of energy required for separation, at low acetate recovery levels, is considerably lower if acetic acid is used in excess. For the hybrid processes, there is an optimum value of acetate recovery that minimizes the total required heat duty and membrane area. Hybrid distillation–pervaporation process allows obtaining the specified product purity with lower energy requirements and more economical tradeoffs than the considered conventional processes. The economic optimum design maximizes energy savings and minimizes total annualized costs. After optimization and energy integration, the best process alternative includes, in a hybrid system, one packed bed reactor, two pervaporation units and a distillation column.     

A comparison of submerged and sidestream tubular membrane bioreactor configurations

This paper provides an improved understanding of the effect of sidestream (SS) and submerged (Sub) MBR configurations on hydraulic and biological system performance for a tubular membrane geometry. Effects of key flow parameters, these being aeration rate (U_G) in the Sub MBR and cross flow velocity (CFV) in the SS MBR, on fouling behaviour have been assessed during short-term flux-step experiments. Both synthetic and real sewage feeds have been used. Series of tests carried out with both feeds indicate the similar fouling behaviour observed for Sub and SS MBRs operated at U_G of 0.07-0.11 m s⁻¹ and CFV of 0.25-0.55 m s⁻¹ respectively. Analysis of the TMP-based parameters determined from the flux-step experiments show the effect of U_G in Sub configuration to be greater than those of CFV in SS MBR, and to be more efficient at higher fluxes (up to 97% decrease in fouling rate for U_G increased from 0.02 to 0.2 m s⁻¹, at 291 m⁻² h⁻¹). The influence of MBR configuration on biomass characteristics was also assessed by acclimatising the biomass at three MLSS concentrations for both configurations and revealed the carbohydrate contained in the biomass supernatant to be a possible indicator of fouling for MBR operation.