Membrane separation and Ultrafiltration-Zurich课件

Table 1: Membrane Materials for Various Applications
Flowsheet
Membrane separation flow patterns are parallel flow, series flow and two-stage flow. Parallel flow schematic is shown in Figure 5. It used when there is no need for a high selectivity in either the permeate or retentate. The advantage is that it if one of the stages gets clogged the entire process does not have to be stopped, where as in series or stage this is not the case. Series flow is depicted in Figure 6 and is used for high selectivity in the retentate. Two stage flow yields a higher selectivity in the permeate and is shown in Figure 7.
Membrane Separation
Table of Contents
Introduction … … … … … ..… … … … … … … … … … … … … … … … … … … … … … … ...1 FlowSheet. … … … … … ..… … … … … … … … … … … … … … … … … … … … … … … … .5 Process Operation … … … … … … … … … … … … … … … … … … … … … … … … … … .7 Limitations ..… … … … … … … … … … … … … … … … … … … … … … … … … … … … … 12 Decision Tree… … … … … … … … … … … … … … … … … … … … … … … … … … … … ..13 Theory on Design Parameters… … … … … … … … … … … … … … … … … … … … … .14 Properties … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … 18 Examples.. … … … … … … … … … … … … … … … … … … … … … … … … … … … … … ..19 Costs … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … 27 Alternatives … … … … … … … … … … … … … … … … … … … … … … … … … … … … … .29 References … … … … … … … … … … … … … … … … … … … … … … … … … … … … … .31
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CHE-396 Senior Design
♦ Porous Membranes
Membrane Separation
Porous membranes are used in microfiltration and ultrafiltration. The dimension of the pores (0.1~10um) mainly determines the separation characteristics. High selectivities can be obtained when the size of the solute is large relative to the pore size in the membrane. Microporous membranes are similar to porous membranes and differ in regards to pore dimension (50~500 angstrom). Refer to Figure 2.
Figure 2: Porous Membrane (separation of smaller species) ♦ Non-Porous Membranes These membranes are capable of separating molecules of the same size, gases as well as liquids. Non-porous membranes do not contain any macroscopic pores. The transport is determined by the diffusion mechanism, which means that components first must dissolve into the membrane and then diffuse through the membrane due to a driving force. Separation is due to differences in diffusivity and/or solubility. These membranes can be found in gas separation. Refer to Figure 3.
Feed Mixture
Retentate
Membrane
Permeate
Sweep (optional)
Figure 1: Basic Membrane Separation Although the majority of time the feed, retentate, and permeate are usually liquid or gas, they may also be solid. The optional sweep is a liquid or gas, used to help remove the permeate. Membrane Structures Because the membrane must allow certain constituents to pass through, they must have a high permeability to certain types of molecules. Membrane structures consist of the following three basic types:
Retentate
Feed
Permeate
Figure 5: Parallel Flow
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CHE-396 Senior Design
Membrane Separation
Feed
Retentate
Permeate
Permeate
Figure 6: Series Flow
Retentate Feed Retentate
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CHE-396 Senior Design Introduction
Membrane Separation
Membrane separation involves partially separating a feed containing a mixture of two or more components by use of a semipermeable barrier (the membrane) through which one or more of the species moves faster than another or other species. As shown in Figure 1, the basic process of the membrane separation involves a feed mixture separated into a retentate (part of the feed that does not pass through the membrane, i.e., is retained) and a permeate (part of the feed that passes through the membrane).
Materials Plyproylene Polysulfone Polyimide Polyamide Polyacrylonitrile Cellulose Membrane Separation Process Microfiltration (MF) Ultrafiltration (UF), Gas Separation (GS) Gas Separation Reverse Osmosis (RO) Ultrafiltration Microfiltration , Ultrafiltration, Reverse Osmosis
CHE-396 Senior Design
Membrane Separation
Membrane Separation and Ultrafiltration
Syed Ali Paul Boblak Efrem Capili Stanislav Milidovich
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CHE-396 Senior Design
Permeate
Figure 7: Two-Stage Flow
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CHE-396 Senior Design Process Operation
Membrane Separation Processes