Fixed-Bed Drying of Air Using Molecular Sieves

Abstract

The rate of drying of air in a fixed bed of molecular sieves was investigated. Exit air moisture content as a function of time was measured at several values of inlet concentration, flow rate, fixed-bed height, and bed temperature. Over-all, solid phase, and gas phase mass transfer coefficients and particle and pore diffusivities were calculated. The pore diffusion model of Vermeulen and Acrivos best reproduced experimental data and is recommended as a basis for design calculations.^he adsorption process for fixed-bed air drying can be * characterized using modifications of standard design procedures. Application of the mass transfer zone (MTZ)

The Kinetics of Adsorption of Methane and Nitrogen from Hydrogen Gas

“…The lack of dependence on pressure indicates that the diffusion mechanism in the adsorbent is either surface migration or Knudscn diffusion, or a combination of these, rather than bulk (or molecular) diffusion. Second, although the data show considerable scatter, it is obvious that k s is a function of Co' The large experimental scatter .in k s values is also apparent in the data of Eagleton and Bliss [7] as weH as that of Nutter and Burnet [13], and is principaHy due to the fact that the value of k s depends on the ratio of the slope of the In(l -C/C o ) VS. t curve to that of the In CIC o VS. t curve. Since, in many instances, these curves are not too linear, it is often very difficult to determine the best value of the slopes.…”

Adsorption of Normal Paraffins from Binary Liquid Solutions by 5A Molecular Sieve Adsorbent

“…The concept of a zeolite resistance also leads to a significant improvement in the interpretation of the data of Nutter and Burnet (1966) for air drying in a fixed bed of molecular sieves. Nutter and Burnet's calculated values of Dpore varied by a factor of 7 over a fourfold range of particle sizes, whereas Z)pore should be independent of the particle size.…”

Dynamic Sorption by Hygroscopic Salts. A Comparative Study

“…A survey of the literature shows intensive studies of silica gel (Bullock, 1965;Bullock and Threlkeld, 1966;Elstonalberg, 1939;Hubard, 1954;Simpson and Cummings, 1964). Molecular sieves (Barrer, 1964;Greismer et al, 1959;Hougen and Dodge, 1947;Nutter and Barnet, 1966), activated alumina (Eagleton and Bliss 1953;Fleming et al, 1964;Getty and Armstrong, 1964), and activated carbon (Allman et al, 1929) have received considerable attention. Work has also been reported on hygroscopic salts such as calcium chloride (Baxter and Starkweather, 1916;Baxter and Warren, 1911), barium oxide (Booth and McIntyre, 1930), and perchlorates (Hammond and Withrow, 1933;Lenher and Taylor, 1930).…”