Membrane systems design manufacturers

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. 

The selection of whose software program to use depends entirely on which membrane manufacturer is specified by the customer. Each RO system designer may have a favorite program that they use to provide projection information should the membranes of choice not be specified. In most cases, it makes sense to run several programs and compare/contrast the differences among them to find which membrane performance meets the requirements of the specific application. 

System design plays a role in determining acceptable recovery by an RO. Flow rates per pressure vessel, recovery per module, and BETA values must all be taken into account when considering acceptable recovery by the RO system (see Chapters 9.4, 9.5, and 9.6). The higher the recovery of the RO system, the closer concentrate flow rates and individual module recoveries come to reaching limits recommended by membrane manufacturers. 

Membrane processes are used to filter liquids. Instead of conventional filter materials (e.g. filter cloth, filter candles,) microporous membranes are employed with molecular size pores. First the industry had to learn how to manufacture membranes with controlled pore sizes. To optimise the filtration capacities specific filter structures had to be designed in which the liquid followed well defined flow patterns on one side of the membrane. Many different systems were developed for the varied applications, all having their advantages and also disadvantages, i.e. plate modules, tubular modules, spiral wound membranes, etc. Research and development in this field is far from being exhausted. Today membrane systems are available which are sufficiently resistant to chemical, mechanical and thermal stress. They are produced from plastic... 

The use of membranes to produce power is an exciting new area for the industry. Although intellectually appealing, commercialization will require significant manufacturing and system design advances. 

The service, backwash and cleaning cycles described above are general in nature and depend on each membrane manufacturer s system design. 

Electrolytic systems of direct and membrane cell design have been employed. However, this technology is not a major factor in current manufacturing practice. 

Diversity of Membrane Eiements and Configurations Currently, all membrane manufacturers offer their own design, size, and configuration of membrane elements and systems. The membrane systems differ by the type of filtration driving force (pressure versus vacuum), the size of the individual membrane elements, the size of the membrane vessels, the configuration of the membrane modules, the type of membrane element backwash, and the type of membrane integrity testing method and other factors. 

There have been a number of cell designs tested for this reaction. Undivided cells using sodium bromide electrolyte have been tried (see, for example. Ref. 29). These have had electrode shapes for in-ceU propylene absorption into the electrolyte. The chief advantages of the electrochemical route to propylene oxide are elimination of the need for chlorine and lime, as well as avoidance of calcium chloride disposal (see Calcium compounds, calcium CHLORIDE Lime and limestone). An indirect electrochemical approach meeting these same objectives employs the chlorine produced at the anode of a membrane cell for preparing the propylene chlorohydrin external to the electrolysis system. The caustic made at the cathode is used to convert the chlorohydrin to propylene oxide, reforming a NaCl solution which is recycled. Attractive economics are claimed for this combined chlor-alkali electrolysis and propylene oxide manufacture (135). 

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