Density-weighted vapor velocity

The superficial, density-weighted vapor velocity, k , is used to size the diameter of distillation columns, absorbers. Section 4. 8, gas-liquid separators or knock out pots, Section 5.1, and face velocity to demisters, Section 9.1. For convenience, values of k are given in Table 4.1 for different applications. 

The model includes parameters for relative volatility a, vapor velocity v, tray spacing flow constant kv, flooding factor //, vapor py and liquid pL densities, molecular weight MW, and some known upper bound on column flow rates FmaX. 

Flooding at the density ratio-weighted superficial vapor velocity, k factor, of 0.1 m/s. 

Grayish metal hexagonal close-packed crystal system, lattice constant, a=2.286 A and c=3.584 A density 1.85 g/cm permeable to x-rays highly ductile modulus to weight ratio very high, elastic modulus 44.5 x 10 at 25°C (for hot-pressed block and sheet) melting point 1,287°C vaporizes at 2,471°C sound transmission velocity 12,600 m/sec reflectivity (white hght) 55% thermal neutron absorption cross-section 0.0090 barns/atom electrode potential, Be/Be2+(aq) 1.85 V electrical resistivity 3.36 x 10-i° ohm.m (at 20°C). 

For vapors, the velocity used will depend on the operating pressure and fluid density the lower values in the following ranges will apply to high molecular weight materials ... 

Fiv = L/G- Dv/A dimensionless, in which L is the liquid rate (weight units) G is the vapor rate (weight units) is the vapor density Di is the liquid density (same units as vapor density) if below about 0.005, is considered to be on the low side. It is possible under such conditions for the high cap-slot velocities to pick up a major fraction of the liquid on the tray and blow it into the exit downcomer, thus bypassing good contact in the active zone of the tray. 

The molecules in a gas have a kinetic energy of X where m is the mass and v is the velocity, or equal to X kT where k is Boltzmaim s constant and T is the temperature in degrees Kelvin. At room temperature X equals 0.025 (Xo) eV. When these molecules strike a surface, they exert a pressure that is measured as force per unit area. The pressure exerted at a given temperature and gas density depends on the atomic/molecular weight of the gas molecules. The pressure is the sum of the forces exerted by all particles impinging on the surface if there is a mixture of gases or of gases and vapors, then each gas or vapor will exert a partial pressure and the total pressure will be the sum of their partial pressures. Molecular... 

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