Carbon dioxide permeability feed pressure

Fig. 15.10 Carbon dioxide permeability of the isotropic HPC matrix versus feed pressure [13]...

Figure 8. Permeability of Lexan polycarbonate to carbon dioxide at 35 °C as a function of C02 partial pressure.Qo, in the presence of 117 mm. Hg of isopentane in the feed , pure C02 Q...

Figure 11.15 The effect of an addition of hexane to a mixture of methane (90%) and carbon dioxide (10%) at a feed pressure of 1025kPag. (a) CO2 permeability, (b) CH4 permeability, (c) CO2/CH4 selectivity. Reprinted with permission from Ind Eng Chem Res., The effect of hydrocarbons on the separation of carbon dioxide from methane through a polyimide gas separation membrane by Hasan, R., C. A. Scholes, C. W. Stevens and S. E. Kentish, 48, 5415-5419, Copyright (2009) American Chemical Society...

Gas permeation systems typically use hollow-fiber or spiral-wound membranes, although hollow-fiber systems are more common tBaker. 2004k Cellulose acetate membranes are used for carbon dioxide recovery, polysulfone coated with silicone rubber is used for hydrogen purification, and conposite membranes are used for air separation. The feed gas is forced into the membrane module under pressure. Retentate, which does not go through the membrane, will become concentrated in the less permeable gas. Retentate exits at a pressure that will be close to the input pressure. The more permeable species will be concentrated in permeate. Permeate, which has passed through the membrane, exits at low pressure. The operating cost for a gas permeator is the cost of conpression of the feed gas and the irreversible pressure difference that occurs for the gas that permeates the membrane. A typical hollow-fiber unit will contain 5000 m membrane area per m at a cost of approximately 200/m. ... 

We want to separate carbon dioxide contaminating methane using a cellulose acetate membrane. The mixture is perfectly mixed on both sides of the membrane. The methane mole fraction in the feed (high-pressure gas) is y(CH4) = 0.90. The permeate pressure is 1.5 atm. At 35 °C ancl 20 tm, the permeability... 

Gas permeation experiments were carried out for carbon dioxide, oxygen and nitrogen. The method used to measure the gas permeability was the constant pressure or variable volume method. For the measurements a home-made system was used [32]. It comprised a two-compartment flat sheet permeability cell. The feed stream circulates in the bottom compartment tangentially to the composite films and permeates through them to be collected in the top compartment where a flowmeter is connected. Due to the asymmetry of the composites the permeation experiments were carried out both for the top and bottom surfaces of the composite films facing the feed stream. 

As an example, the permeability to carbon dioxide of the isotropic HPC matrix is shown in Fig. 15.10, as a function of feed pressure. It was observed that the permeabilities decrease in the order of F(C02) > F(02> > F(N2>. The higher CO2 permeability is probably due to the relative high solubility of this gas in the HPC matrix when compared with O2 and N2. The permeability of CO2, O2 and N2 increases linearly with the upstream pressure and it is always higher for the bottom surface. The data collected in Table 15.2 show that HPC matrix (0% w/w HPC) has... 

An equimolar mixture of carbon dioxide and nitrogen is separated by a module containing composite membranes with an I DM toplayer with a thickness of 1 pm. The feed pressure is = 2.5 bar and the penneate pressure Pp = 0.5 bar.. The feed rate is q = 36 np (STP)/h. The permeability for the two gases is Pqqj = 81 Barrer and = 5.3 Barrer, respectively. Assume that perfect mixing occurs at feed side and permeate side. 

Of the two developing membrane processes Usted in Table 3, gas separation and pervaporation, gas separation is the more developed. At least 20 companies worldwide offer industrial membrane-based gas separation systems for a variety of applications. In gas separation, a mixed gas feed at an elevated pressure is passed across the surface of a membrane that is selectively permeable to one component of the feed. The membrane separation process produces a permeate enriched in the more permeable species and a residue enriched in the less permeable species. Important, well-developed applications are the separation of hydrogen from nitrogen, argon, and methane in ammonia plants the production of nitrogen from air the separation of carbon dioxide from methane in natimal gas operations and the separation and recovery of organic vapors from air streams. Gas separation is an area of considerable current research interest the munber of applications is expected to increase rapidly over the next few years. 

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