Fehlerbetrachtung bei der Messung der theoretischen Bodenzahl von Destillationskolonnen

Structured packing efficiency—Vital information for the chemical industry

“…b Range 0-900 • C. uum range, absolute deviations amount to about 0.002. This difference seems to be very small but it results in deviations for the calculation of the number in theoretical stages of up to 2%, as can be shown using the method of Deibele and Brandt (1985).…”

“…It can be concluded, e.g. from Deibele and Brandt (1985), that the error is usually low provided the assumptions are met, the concentration range the measurement is made in is restricted, the number of stages is properly chosen and good parameters have been used for evaluation. In the pressure range mentioned above, an error of 1% can be expected from uncertainties in available (measured) relative volatility data, errors <0.5% will have to be expected if the concentrations during measurement are limited to the range 9-91 mol% and a theoretical stage number around 20 is chosen (Adrian, 2009).…”

Proposal for a Viscous Test Mixture—Densities, Viscosities, and Vapor–Liquid Equilibrium Data of the Binary Mixture 2-Methyl-2-butanol + 2-Methyl-1-propanol

“…The number of effective separation stages is extracted following the approach of Fenske–Underwood. To satisfy the underlying assumptions of this approach, the component system has to meet a comprehensive set of criteria: both constituents should be well-defined pure components available at high purity to eliminate trace effects of high or nonboiling impurities specifically racemic systems should be avoided relative volatility should be in the range of 1.1 ≤ α = ( y / x ) 1 /( y / x ) 2 ≤ 2.0, to allow for a reasonable separation with 15 to 20 theoretical stages , complete miscibility should be given over the full concentration and temperature range boiling temperatures at p ≥ 2 kPa should be in the range of 30 to 150 °C VLE should be close to ideal, i.e., α being almost constant over the column height liquid phase viscosity at separation conditions should be around 0.5 mPa s to 10 mPa s with a small concentration but pronounced temperature dependency no viscosity increasing nonboiling components should be added to avoid concentration of the nonboiling component near the vapor−liquid interface. Otherwise the local viscosity instead of the bulk viscosity as well as concentration polarization had to be considered the liquid phase should show Newtonian flow behavior components should have a low hazard potential with respect to EHS issues to ease experimental procedures the melting point should be below 40 °C price and availability of the candidates should be acceptable Using the data bank of CHEMCAD, Chemstations, the viscosities resulting from the boiling temperatures in the pressure range from 2 to 100 kPa have been calculated.…”

“…relative volatility should be in the range of 1.1 ≤ α = ( y / x ) 1 /( y / x ) 2 ≤ 2.0, to allow for a reasonable separation with 15 to 20 theoretical stages , …”

“…Hence, among the remaining alcohols and diols combinations have been identified, giving a relative volatility in the range stated above. The relative volatility may not be too high to achieve a high accuracy in the determination of separation efficiency . Hence, at sufficient bed heights, given accuracies of VLE data and the measurement of the composition of a sample, the separation factor of a potential test system may not be too high.…”