Design of membrane systems

Marriott, J. and E. Sprensen, The optimal design of membrane systems. Chemical Engineering Science, 2003, 58(22) 4991 5004. 

The focus in the thin film research impact area is to develop a fundamental understanding of how morphology can be controlled in (1) organic thin film composites prepared by Langmuir Blodgett (LB) monolayer and multilayer techniques and (2) the molecular design of membrane systems using ionomers and selected supported liquids. Controlled structures of this nature will find immediate apphcation in several aspects of smart materials development, particularly in microsensors. 

Kev>erse Osmosis (RO) Membranes A type of membrane system for treating oily wastewater is currently undergoing commercialization by Bend Research, Inc. The system uses a tube-side feed module that yields high fluxes while being able to handle high-sohds-content waste streams (Ref. 25). Another type of reverse osmosis technique is being designed to yield ultrapurified HF recovered from... 

CHAPTER ELEVEN Design of membrane-separation systems... 

EJ-Haiwagi, M. M. (1993). Optimal design of membrane hybrid systems for waste reduction. Sep. Sci. TechnoL, 28(1-3), 283-307. 

Muralikrishnan, G., Crabtree, E., and El-Halwagi, M. M. (1996). Design of Membrane Hybrid Systems for Pollution Prevention." AIChE Spring Meeting, New Orleans, LA. 

The only feasible procedure at the moment is molecular dynamics computer simulation, which can be used since most systems are currently essentially controlled by classical dynamics even though the intermolecular potentials are often quantum mechanical in origin. There are indeed many intermolecular potentials available which are remarkably reliable for most liquids, and even for liquid mixtures, of scientific and technical importance. However potentials for the design of membranes and of the interaction of fluid molecules with membranes on the atomic scale are less well developed. 

A different but very important area of chemical engineering in the life sciences involves the design and manufacture of health care systems for diagnostic or therapeutic purposes. Consider the example of controlled release drugs or dermal penetration drugs. Here the emphasis is on the system rather than on the compound. The design of these systems requires an understanding of reactions, kinetics, fluid mechanics, and membrane systems. 

Several field test studies have been undertaken utilizing the SEPAREX process in a 2-in. diameter element size Due to the modular configuration of membrane systems, a full size system can be directly designed from the test results with a small pilot plant. Although the flow rates for a pilot unit are considerably lower than might be encountered in a full-size system, all process parameters such as product purities, pressure drop, product recoveries, optimum pressure and temperature, membrane area required and series/parallel arrangement of the elements can be directly determined. 

Plate-and-frame modules were one of the earliest types of membrane system. A plate-and-frame design proposed by Stem [110] for early Union Carbide plants to recovery helium from natural gas is shown in Figure 3.38. Membrane, feed spacers, and product spacers are layered together between two end plates. The feed mixture is forced across the surface of the membrane. A portion passes through the membrane, enters the permeate channel, and makes its way to a central permeate collection manifold. 

Ole Jentoft Olsen (DSS Danish Separation Systems) presented a large-scale industrial example on using ultrafiltration for the production of antibiotics. Within 15 hr, a volume of 100 metric tons of biomass was processed. The design of membrane module, operational conditions, and the overall plant were presented, along with detailed cost considerations for this process. 

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