Module Design and Construction

The stacked planar module design is readily used with any foil-based membrane because foils are available as flat sheet stock. This design is not so readily adapted 

The tube-and-shell, or tubular, membrane module is easily adapted for use with drawn tubular membranes as well as membranes that are made by depositing a thin permselective metal layer onto a porous tube support. There are three significant variants to this module design. One is based on the membrane tubes fixed to a header at each end of the membrane tube. The second is similar in that both ends of the membrane tubes are fixed to a header, but to the same header. In the second design, the membrane tubes are bent into a U shape, which can be easily done with small diameter metal tubes. The third is based on a single header, to which open sides of closed-one-ended membrane tubes are fixed. The closed-ends of the membrane tubes are suspended freely. This latter design is more common for commercial applications, due to free thermal expansion and greater membrane durability (see above discussion), whereas laboratory test-and-evaluation practices favor the first variant for its ease of assembly. If the membrane is a drawn, thin-walled tube, the membrane tube will usually be brazed to the header. This is more difficult if the membrane tubes are to be fixed at both ends to head- 

Regardless of the membrane module design, effective performance is dependent on rapid mass transfer at the feed side of the membrane. There are several comprehensive references on mass transfer [10], so it will not be addressed in detail here. However, one should consider mass transfer because it affects two design issues the manifolding of the feed stream to each membrane, and the feed channel design and dimensions. The detailed analysis of these issues differs somewhat when one considers stacked planar modules and tubular modules, but the fundamental objectives are quite similar. 

The configuration of the feed charmel is also important If one assumes that the entire feed stream is fed by serial flow through the membrane module, then one can calculate the residence time, or space velocity, for the feed gas as it passes over each membrane. In the worst case, the flow will not be turbulent, and diffusion will be the dominant means by which hydrogen will travel from any point within the feed channel to the membrane surface. Obviously, if hydrogen does not contact the membrane surface, it cannot permeate through the membrane. In this analysis, one needs to estimate the average rate of gas-phase diffusion of hydrogen relative to the residence time that the feed stream is in the feed channel. Cussler [11] has analyzed this type of problem and provides a simple equation to determine if diffusion will be sufficiently rapid  

Where X is the distance that hydrogen must diffuse to contact the membrane surface, D is the gas-phase diffusion coefficient for hydrogen at the temperature and pressure of operation, and t is the residence time for the feed stream in the feed channel of the membrane. If B is less than 1, then gas phase hydrogen diffusion is relatively fast on the time scale of interest, whereas if B is greater than 1, then the gas phase hydrogen diffusion is too slow. 

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This chapter will address the special considerations that apply to incorporating dense, hydrogen-permeable metal membranes into practical membrane modules for commercial and industrial use. It is organized to present a brief historical overview, a general review of hydrogen-permeable metal membranes, scale-up from laboratory test-and-evaluation membrane modules to commercial membrane modules, membrane module design and construction, and commercial applicability. 

We have shown that redox chromophores organized in LB films with resped to their orientation, alignment, or electronic interactions make very useful and specific photoresponses such as amplified fluorescence quenching, photocurrents controlled at the molecular level, photoinduced anisotropic eledrochromism, and photochemically modulated second harmonic generation. These results may contribute to facilitate the design and construction of novel photonic devices in the near future. 

Bundle Preparation. Packages of multifileiment yarns are backwound to prepare bundles necessary for the manufacture of a reverse osmosis module. A proprietary winder for this operation has been designed and constructed at Albany International Research Co. This device is capable of helically winding multifilament yarns into bundles around a mandrel. This is done in a manner such that the resulting bundle has uniform cylindrical dimensions and uniform fiber density. This minimizes channeling and optimizes exposure of membrane surface area. 

More recently, the second-generation molecular shuttle 374+ (Fig. 13.32) was designed and constructed.38 The system is composed of two devices a bistable redox-driven molecular shuttle and a module for photoinduced charge separation. In the stable translational isomer, the electron-accepting cyclophane 124+, which is confined in the region of the dumbbell delimited by the two stoppers Tj and T2, encircles the better electron donor tetrathiafulvalene (TTF) station. 

The success of EDR in water demineralization has apparently resulted from its greater tolerance of particulate and fouling matter compared to reverse osmosis greater forgivingness of process upsets greater tolerance for unskilled operators simplicity in design and construction of EDR stacks compared to reverse osmosis modules the ability to inspect, dean, or replace one membrane at a time the existence of a comprehensive global sales and... 

The number of modules present in the work envelope of a robot arm varies with the number of tasks it is to perform in a given process. Some modules can be as complex as self-contained workstations. Although most of the modules required for the different steps of the process can be provided by either the arm s, or an alternative, manufacturer, some users design and construct their own modules, either because of the specificity of the task or with a view to reducing costs. A detailed discussion of such custom modules is obviously beyond the scope of this chapter. What follows is thus a brief description in relation to solid sample handling. 

Today, major hopes are placed on the use of microelectromechanical systems (MEMS) for future NIR imaging schemes. In addition, individual submillimeter (50 X 50 gm ) modules that integrate an interferometer and a detector are becoming available [62] which, when arranged in arrays, will allow the design and construction of low-cost and robust hyperspectral imagers [63]. 

Our aim was to design and construct a mobile automated system, performing survey analyses at a rate of 1-5 analyses per hour on the hour."Figure 4" shows the operational principle of the instrument. It consists of compact module units, which may be arranged for specific applications and serve different needs (j, 2). 

Neither the practising analytical scientist nor indeed many analytical instrument makers would willingly embark upon ab initio design and construction of MMW oscillators or detectors. It is much more likely they would purchase the oscillator modules available from the specialist MMW component suppliers. This section aims to help the reader make an informed decision on the suitability of a device for the experiment being planned. 

The audit of the Service Jack 1 project is the only one of the fourteen reports to focus on the design and construction phase. Some new cranes, an office module and a larger accommodation module at Ekofisk field were to be constructed. A large part of the actual work was to be done in Indonesia. The inspection was conducted by interviews and documentary research at the supplier Master Marine s project offices in Oslo and Singapore, and through a visit to the production plant... 

This shows that all these systems have already left the experimental R D stage and become an economic reality. They have already demonstrated lower consumption of natural fossil fuels per unit of power generated and lower emission of greenhouse gases and other harmful products. Other advantages over thermal power plants are associated with fuel cell-based power plants. They can be produced in modules, from which power plants of different size and output can be put together. This attribute, known as scalability, facilitates the design and construction of plants adapted to specific local requirements. 

Recently, a reformer and membrane modules (RMM) test plant having the capacity of 20 Nm /h of hydrogen has been designed and constructed by Tecnimont KT near Chieti, in Italy. This plant is described in Chap. 10 of this... 

The demonstration house designed and constructed by NESTE (Helsinki, Finland) incorporates many building components and materials all made of plastic (75%), featuring see-through silica modules as window glass and crystal-silicon sun shades on the south facade to reduce summer cooling loads, while GE Plastic s living environments model... 

In this pap>er were presented first steps, which guide to the design and construction of a VHGT attached WDM triplex transceiver module TRx using polymer PLC hybrid integration technology. We report on the results measuring of the optical attenuation of the... 

Kuiper s group also described the design and construction of a camera module for use in a mobile phone by using this variable focus lens [21]. Figure 5.30 shows a cross section of the module and photographs of the... 

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