Membrane Modules for Gas Separations

A two step reformer and membrane modules (RMM) test plant having the capacity of 20 N m h has been designed and constructed to investigate at an industrial scale level the potentialities of this kind of architecture. At a reaction temperature of 620 °C, steam to carbon ratio of 4.8 and a membrane temperature of 430 °C, an overall yield of 59% is achieved. By properly 

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Design of Membrane Modules for Gas Separations The advantages of spiral-wound modules are ... 

Figure 19.6. Gas permeation equipment and performance, (a) Cutaway of a Monsanto Prism hollow fiber module for gas separation by permeation, (b) Flowsketch of a continuous column membrane gas separator, (c) Composition profiles of a mixture of C02 and Oz in a column 5 m long operated at total reflux [Thorman and Hwang in ( Turbak, Ed.), Synthetic Membranes II, American Chemical Society, Washington DC, 1981, pp. 259-279],...

The goal of the model for membrane unit for gas separation is to predict the flow rate and composition of retentate and permeate streams, for a given feed stream containing n components, membrane type and area, and permeate pressure. Here, the process boundary and variables are limited to one of the membrane modules shown in Figure 4.5. In this section, the solution-diffusion mechanism is used to predict the separation behavior of the membrane. In the development of a membrane model, it is assumed that the process is at steady state, pressure is constant on feed side, and permeability of a component through the... 

Ahmad, R, Lau, K.K., Lock, S.S.M., et al. (2015) Hollow fiber membrane model for gas separation systems experimental validation, process simulation and module characteristics study. Journal of Industrial and Engineering Chemistry, 21,1246-1257. 

Figure 13.8 Schematic representation of membrane reforming reactor integrated with a gas turbine (1) Combustion chamber (2) hydro-desulfurization unit (3) convective furnace (4) and (5) membrane modules for H2 separation (6) H2 compressor.

Abstract This chapter focuses on the operating experience and the results obtained from experiments carried out at a natural gas steam reformer plant integrated with Pd- and Pd-Ag-based membrane modules for hydrogen separation. The plant is based in Chieti Scalo, Italy, and was developed within the framework of an Italian research project entitled Pure hydrogen from natural gas reforming up to total conversion obtained by integrating chemical reaction and membrane separation . 

The efficiency of membrane separation increases with the permeability and the selectivity. Thin membranes are economic, since according to Equation (2.1) the gas flow is inverse proportional to the layer thickness. However thin polymeric films, which have favorable permeability and selectivity, are too weak to withstand the high pressure difference between permeate and retentate side. The economic breakthrough set in with the production of ultrathin compound polymeric membranes. These are designed as hollow fibres with a thick porous back-up layer for mechanical stability and a thin dense non porous membrane layer for gas separation. The porous layer only has a slight influence on gas separation. These hollow fibres are combined in a bundle, which is arranged in a cylindrical container [2.13]. Several of these bundles, also called modules, can be added to... 

Another field of interest is to create close-packed SURMOFs for use in membranes with high separation performance. Guo et al. created nano-HKUST-1 membranes on an oxidized copper grid that showed a high permeation flux and excellent permeation selectivity for H2 over CO2, N2, and CH4. More recently, Caro et al. and Brown et al. prepared a series of improved nano-ZIF-8, nano-ZIF-7, nano-ZIF-90, and nano-ZIF-22 membranes that exhibited much better selectivities for H2, by choosing nanoMOFs whose pore dimensions were close to the size of 50,86,87 xhey also formed nano-ZIF-90 membranes on polymeric hollow-fiber supports to fabricate high-surface-area membrane modules. The gas separation factors, permeances and selectivities of the polymeric-supported nano-ZIF-90 membrane indicated that it should be able to separate liquid alkanes (Figures 7a-f) ... 

Fig. 23. Two types of hollow-fiber modules used for gas separation, reverse osmosis, and ultrafiltration applications, (a) Shell-side feed modules are generally used for high pressure appHcations up to - 7 MPa (1000 psig). Fouling on the feed side of the membrane can be a problem with this design, and pretreatment of the feed stream to remove particulates is required, (b) Bore-side feed modules are generally used for medium pressure feed streams up to - 1 MPa (150 psig), where good flow control to minimise fouling and concentration polarization on the feed side of the membrane is desired.

See also Gas separation adsorption adsorbents for, 1 612 coal gasification, 6 824 commercial separations, l 618t hollow-fiber membrane modules for, 15 823... 

High-pressure gas separation, hollow-fiber membrane modules for, 15 823 High pressure liquid chromatography (hplc), 9 234 21 275 in herbicide analysis, 13 312 polymer analysis using, 19 566 High-pressure methanol, production process, 16 300-301 High pressure methods, specialized, 13 430-431... 

Low polarity plasticizers, 74 479 Low power package, 74 863 Low pressure catalytic processes, 20 151 Low pressure chemical vapor deposition (LPCVD), 5 807, 811-812 Low-pressure gas separation, spiral-wound membrane modules for, 75 823-824 Low pressure hollow-fiber membranes, 76 24-26... 

Figure 4.16 An illustration of a counter-flow module for the separation of nitrogen from air. Directing the permeate to flow counter to the feed sweeps the permeate side of the membrane with a flow of oxygen-depleted gas. This increases the oxygen flux and decreases the nitrogen flux through the membrane...

The development of high-flux anisotropic membranes and large-surface-area membrane modules for reverse osmosis applications in the late 1960s and early 1970s provided the basis for modem membrane gas separation technology. The first company to establish a commercial presence was Monsanto, which... 

Polymeric flat sheet membranes are easy to prepare, handle, and mount. For gas separation, the flat sheet membranes are composites with a selective polymer coated on a support. A commercial configuration that has been quite successful for hydrocarbon vapor recovery is the Borsig envelope type module (see Figure 4.19) [107]. Packing densities for flat sheet membranes may be in the range of 100 00 m /m [1]. 

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