Compact Membrane Systems

Since the pioneering work of Tehennepe et al. [152] in 1987, many efforts have been made filling the polymeric matrix with zeolites in order to improve their stability. There are several companies that offer pervaporation organic membranes and composite membranes such as Sulzer Chemtech [153]. Commercial pervaporation and vapor permeation installations utilize polymeric membranes, like PVA (Sulzer Chemtech), polyimide (Vaperma), per-fiuoropolymers (MTR and Compact Membrane Systems), and polyelectrolytes (GKSS) or ceramic membranes, like zeolite A (Mitsui, Mitsubishi, Inocermic) and silica... 

The third polymer hsted in Fig. 7.4 has a very different structure in comparison with the polyacetylenes. The Teflon AF2400 is a perfluorinated random copolymer composed of 13 mol% tetrafluoroethylene and 87 mol% 2,2-bis(tri-fluoromethyl)-4,5-difluoro-l,3-dioxole. Its extraordinarily high gas permeabiUty was first described by Nemser and Roman [287]. Composite membranes fabricated from this polymer are currently being tested on a pilot scale by Compact Membrane Systems, Wilmington. An attractive application seems to be the production of oxygen-enriched or oxygen-depleted air for mobile diesel engines [288] and the separation of supercritical carbondioxide [289]. 

Compact Membrane Systems website, http //www.compactmembrane.com/... 

Dry Nitrogen Seal. The dry gas seal for the offshore platforms and LNG terminals use portable inert gas generators to reduce the emission of the greenhouse gases like methane. Compact membrane systems have been designed by various vendors for use in these hazardous environments. 

Ion-selective electrodes are membrane systems used as potentiometric sensors for various ions. In contrast to ion-exchanger membranes, they contain a compact (homogeneous or heterogeneous) membrane with either fixed (solid or glassy) or mobile (liquid) ion-exchanger sites. 

Fig. 27. A Principle of a plant for Cr(III)/Cr(VI) oxidation and electro-dialytic Fe-removal [90] B Compact electrolysis-membrane system (Photograph supplied by Heraeus Elektrochemie)...

The construction and preparation of these electrodes were described in chapter 3.1. The modern version of this electrode, produced by Radelkis, Budapest, is a compromise between the original construction described by Pungor etal. [310,311, 313] and a system with a compact membrane. Electrodes with silver chloride, bromide and iodide are manufactured. According to the manufacturer these electrodes should be soaked before use for 1-2 hours in a dilute solution of the corresponding silver halide. They can be used in a pH region from 2 to 12 and the dFisE/d log [X ] value is approximately 56mV. These electrodes can be employed for various automatic analytical methods (see chapter 5). They can readily be used in mixtures of alcohol with water, for example up to 90% ethanol and methanol and up to 4% n-propanol and isopropanol [196]. In mixtures of acetone-water and dimethylformamide-water, they work reliably only in the presence of a large excess of water [197]. 

A glass membrane in an electrolyte solution cannot be taken to be a homogeneous system in the direction perpendicular to the surface. When the membrane is in contact with the solution, water molecules can enter it and form a 5-100 nm thick hydrated layer [319]. The formation of this hydrated layer is actually a condition for good functioning of the glass electrode. The basic characteristics of the glass structure probably do not change in the hydrated layer, but the cation mobility increases considerably compared with the compact membrane interior... 

Any dialogue on meat flavor development and deterioration requires a brief discussion of muscle structure. Muscle has a highly compact and complex multicellular structural organization (Figure 2). Individual muscle cells contain numerous mitochondria and nuclei. They also contain contractile elements as the bulk of their structure. While the sarcoplasm of muscle (the aqueous non-organellar component) is small compared to the cytoplasm of non-muscle cells, it does have a highly evolved system of membranes called the SR/L representing an acronym for sarcoplasmic reticulum/lysosomal membrane system (11). The SR/L surrounds each contractile element (Fig. 9-13 in 12 Fig. 7-10 in 13). The close proximity of the SR/L to the contractile proteins situates the proteins in a location that is optimal for their hydrolysis by lysosomal hydrolases (12, 13). 

The pretreatments, described above, that deliver a particulate-free stream at 38 °C to the amine system provide a ready-made feed for processing via membrane modules. This feed can be used with simple and efficient membranes, new structured sorbents, membrane + structured sorbent hybrid systems or more advanced super H2 selective membranes. These membrane systems can simplify and condense the flow sheet in Figure 7.10, thereby enabling a more compact plant with less piping and associated maintenance concerns. 

FIGURE 17 Compact nitrogen enrichment membrane system. (Courtesy Air Liquids.)... 

Figure 8.1 Shows the projected performance of an RO membrane system with ideal, marginal and inadequate pretreatment.1 After an initial period over which time new membranes stabilize performance, a system with ideal performance will show only a slight decline in performance with time due to compaction and the inevitable fouling and scaling that will occur despite good pretreatment and system hydraulics. Marginal pretreatment exhibits more rapid decline in performance than the system with ideal pretreatment. Initial cleaning may be able to revive most of the performance, but after time, foulants and scale that were not removed become irreversibly attached to the membrane and cannot be cleaned away. The RO system with inadequate pretreatment will show very rapid decline in performance that typically cannot be recovered by cleaning the membranes. An RO system with less than ideal pretreatment faces frequent cleaning intervals and short membrane life. Frequent cleaning and membrane replacement costs money, time, and the environment.

Ishida, T. et al., R D of compact detritiation system using a gas separation membrane module for the secondary confinement, Fus. 

Membrane systems give a compact and modular constmction, which occupies less floor space in comparison to the conventional treatment systems. This becomes extremely attractive in the land-scarce countries such as Japan and Singapore. 

Since the first industrial developments in cross-flow MF in early 1980s, significant progress was achieved with ceramic membranes presently, affording new products with improved permeate flux, separation selectivity, and system compactness. Effectively, monolithic and hollow fiber elements have resulted in a significant increase in membrane surface to volume ratio, closer to the compactness of polymeric membrane systems. Ceramic nanofilters are able... 

This chapter will describe some of the market forces driving m brane growth in natural gas treatment, explore some of the competing technologies to CA membranes, examine membrane compaction and the implication to long-term performance, report both recent laboratory and field studies with CA membranes and comment on some of the technical challenges and trends existing today in natural gas treatment with membrane systems that would benefit from future research and development activities. 

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