Venting channel system

Sherman, M. P., S. R. Tiezsen, W. B. Bendick, W. Fisk, and M. Carcassi. 1985. The effect of transverse venting on flame acceleration and transition to detonation in a large channel. Paper presented at the 10th Int. Coll, on Dynamics of Explosions and Reactive Systems. Berkeley, California. 

Membrane gas-separation systems have found their first applications in the recovery of organics from process vents and effluent air [5]. More than a hundred systems have been installed in the past few years. The technique itself therefore has a solid commercial background. Membranes are assembled typically in spiral-wound modules, as shown in Fig. 7.3. Sheets of membrane interlayered with spacers are wound around a perforated central pipe. The gas mixture to be processed is fed into the annulus between the module housing and the pipe, which becomes a collector for the permeate. The spacers serve to create channels for the gas flow. The membranes separate the feed side from the permeate side. 

In the case of flash degassing, the polymer solution is first heated under pressure to above the boiling point of the volatile components and decompressed directly into the ZSK. The polymer and solvent (monomer) spontaneously separate from each other inside the ZSK and the majority of the volatile components are released via the back venting system. Depending on the pressure and the temperature, up to 90% of the solvent can be removed in this way. Efficiency depends on the temperature of the polymer solution at the feed intake, the pressure drop in the back vent, and the material properties of the feeding system. The back vent is located upstream from the polymer or polymer solution feeding port (see Fig. 10.2). In this case, there is no melt in the screw channel so that the entire screw cross-section is available for the removal of gas or vapors. 

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