Of vapor-gas mixtures

In the separation of vapor/gas mixtures, rubbery polymers, such as silicone rubber, can be used to permeate the more condensable vapor components, or glassy polymers can be used to permeate the smaller gases. Although glassy, gas-permeable membranes have been proposed for a few applications, most installed plants use... 

M.-D. Jia, B. Chen, R.D. Noble, and J.L. Falconer, Ceramic-zeolite composite membranes and their application for separation of vapor/gas mixtures, 7. Membrane ScL 90 (1994). 

Adiabatic saturation temperature Final temperature reached by a small quantity of vapor-gas mixture into which water is evaporating. It is sometimes called the thermodynamic wet-bulb temperature. 

The catalytic vapor-phase oxidation of propylene is generally carried out in a fixed-bed multitube reactor at near atmospheric pressures and elevated temperatures (ca 350°C) molten salt is used for temperature control. Air is commonly used as the oxygen source and steam is added to suppress the formation of flammable gas mixtures. Operation can be single pass or a recycle stream may be employed. Recent interest has focused on improving process efficiency and minimizing process wastes by defining process improvements that use recycle of process gas streams and/or use of new reaction diluents (20-24). 

When moisture films are formed, water vapor can accelerate the corrosion rate. Hence, it is necessary to maintain the temperature above the dew point of the gas mixture by at least 20°C, to prevent the formation of moisture films. A temperature of 130°C or above, at atmospheric pressure, can be used for all mixtures of HCl gas and water vapor because the a2eotropic boiling point is 108.6°C. The boiling point of a2eotropic mixtures can be used as a guide at other pressures (see Table 6). 

In engineering appHcations, the transport processes involving heat and mass transfer usually occur in process equipment involving vapor—gas mixtures where the vapor undergoes a phase transformation, such as condensation to or evaporation from a Hquid phase. In the simplest case, the Hquid phase is pure, consisting of the vapor component alone. 

Example 6 Solvent Rate for Absorption Let us consider the absorption of acetone from air at atmospheric pressure into a stream of pure water fed to the top of a packed absorber at 25 C. The inlet gas at 35 C contains 2 percent by volume of acetone and is 70 percent saturated with water vapor (4 percent H2O by volume). The mole-fraction acetone in the exit gas is to be reduced to 1/400 of the inlet value, or 50 ppmv. For 100 kmol of feed-gas mixture, how many Idlomoles of fresh water should be fed to provide a positive-driving force throughout the pacldug How many transfer units will be needed according to the classical adiabatic method What is the estimated height of pacldug required if Hqq = 0.70 m ... 

Physical and Chemical Properties - Physical State at 15 X and I atm. Liquid Molecular Weight Mixture Boiling Point at I atm. 310 - 395, 154 - 202, 427 - 475 Freezing Point Not pertinent Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 0.93 1.05 at 25°C (liquid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat cf Combustion (est.) -17,600, -9,800, -410 Heat of Decomposition Not pertinent. 

A. Bras, G. H. Design of Gooler-Gondensers for Vapor-Gas Mixtures—11, Chem. Eng, p. 238, May (1953). 

The total pressure can be regarded as a sum of the parts furnished by the individual pressures exerted by each of the components of the gas mixtures. The pressure exerted by each of the gases in a gas mixture is called the partial pressure of that gas. The partial pressure is the pressure that the gas would exert if it were alone in the container. In the example of Figure 4-3, the total pressure in the third bulb is 113 mm. The partial pressure of water vapor in this bulb is 20 mm and the partial pressure of air is 93 mm. 

TVP [True vapor-phase] A thermal cracking process in which vaporized petroleum oil is contacted with a hotter gas such that the temperature of the gas mixture is approximately 500°C. Used in the 1930s, but supplanted by various catalytic cracking processes. 

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