Mixed gas systems

Equations (1.4), (1.5), and (1.6) can be applied only to single component gas systems. Next, we shall derive the corresponding equations for the mixed gas systems. In a phase under consideration there are many gases designated by 1, 2, 3, 4,. with n, n2, n, n, ..., rii,... moles (the mixed gas system is thermodynamically considered to be one phase except for special cases). The partial pressure of gas i , Pi, is defined as the product of the mole fraction of that species and the total pressure (P), namely... 

The relation between the partial molal free energy and the fugacity for the mixed gas system has been obtained. 

A. Boundary Between Well-Mixed Gas (System B) and Stagnant Liquid (System A)... 

Figures 9 and 10 show such single pulse measurements made in our laboratory for methane and methane in a mixed gas system (10). Since this early work broad band CARS has been developed and applied to more and more complex systems including single pulse...

Only the fugacity change with respect to pressure and temperature variation has been considered for the pure gases. For a mixed gas system, interactions between the different gas molecules and atoms must also be taken into account. The second virial coefficient, Bm(T), for a binary mixture between molecules 1 and 2 can be expressed as... 

FIG. 1—Schematic of a three-pollutant gas, flowing mixed gas system. 

Michaslis T.B. "Techniques to Detect Failure in Carbon Adsorption Systems," EPA Report340/1—80011, April 1980. USP 8,016,914 claims use of temperature to manage operation of twin adsorption beds — used for recovery of hydrogen from mixed gas systems. The claims include only operation of pressure swing systems for adsorption of hydrogen, and not recovery of solvents from activated carbon. 

Fig. 8.15 Density profiles of CH and in the DP with the pore mouth A (a) pure gas system, (b) mixed gas system (AP=0.5 MPa for pure gas, APjj=0.5 MPa for mixed gas, temperature 300 K). (From [11])...

For the CMS 800-2 membrane there is no theoretical tools and associated parameters to predict the permeability for the mixed gases. The only available ta are the permeability data for the ptrre gas and mixed gas system as shown in Table 8.23. 

Fignre 8.63 shows the prediction for the mixed gas system using the peremabili-ties evaluated by Eqs. (8.36) and (8.37) for Ultem 1000 and the permeabilites mentioned above for CMS 800-2. CO2 permeability as well as C02/CH ideal separation factor are plotted versus the total gas pressure. The data calculated by the transport models agree with the experimental data reasonably well. As expected the values calculated by the Bmggeman s model are generally higher than those calculated by the Maxwell model. 

Measurement of Oxygen Permeation in Mixed Gas Systems An Altemative to Gas Chromatography... 

The leak rate of the probe chamber prevented the determination of oxygen transport in-situ. If this leak rate could be minimized, instantaneous oxygen measurements would lend themselves to the study of systems as steady-state is approached. The time-lag method for estimation of the difftision coefficient could be extended to mixed gas systems. 

In order to control the oxygen partial pressure in the atmosphere, a buffer system, either CO2-CO, H2O-H2 or CO2-H2, was used. In the phase relationships in which (02) was controlled by means of mixed-gas system, P(02) measured with oxygen sensors was compared with P(02) calculated from the mixing ratios of COj/CO, H2O/H2 or CO2/H2. And when they were identical within experimental error, the phase relationships reported are given. It is almost meaningless to use the atmospheres of mixed gas systems which are not in equilibrium in the atmosphere for determining equilibrium oxygen partial pressure values of the solid phases, even if it is measured with a ( 2) sensor (Takayama and Kimizuka 1979). 

Example for the prediction of a membrane performance on the basis of IR studies for the mixed-gas system CO /CH on a ZIF-8 membrane. IR studies gave an adsorption selectivity of COj/CH = 3.5 and a diffusion selectivity C02/CH = 1.4. This results in a predicted membrane selectivity C02/CH = 4.9. Also Grand Canonical Monte Carlo calculations predict this selectivity. Independent permeation studies showed for the mixture CO /CH a selectivity of about 3.5 [45]. 

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