Dixon rings

For vacuum distillations the maximum allowable pressure drop will be determined by the process requirements, but for satisfactory liquid distribution the pressure drop should not be less than 8 mm water per m. If very low bottom pressures are required special low pressure-drop gauze packings should be considered such as Hyperfil, Multifil or Dixon rings see Volume 2, Chapter 4. 

The effect of an increasing flow of liquid with 3 inm Wilson spirals is shown in Fig. 105. A very favourable pressure drop relationship is found with wire gauze e.g. Dixon) rings, as can be seen from Fig. 106 and 107. The figures plotted are average values obtained with a number of different test mixtures. 

Rings Usually made of glass of an appropriate size for the column but can be made of porcelain, stainless steel, aluminum, copper, or nickel. Depending upon design they can be termed Raschig, Lessing, or Dixon rings... 

In the present work, the mass transfer performance characteristics of CO2 into aqueous monoethanolamine (MEA) and diethylenetriamine (DETA) solutions were investigated in an absorption eolumn paeked with a Dixon ring at 303 K and at atmospheric pressure. The mass transfer performance was investigated in terms of volumetric overall mass transfer eoefSeient (.SIgUv). Predictive correlations of for CO2 absorption into MEA and DETA were sueeessfiilly developed. The predicted K(ya values were in relatively good agreement with the experimental values with AAD of 14% (for MEA) and 16% (for DETA). 

The experiments were conducted in an absorption column, which is made of acrylic plastic and enwrapped by thermal insulation material. A Dixon ring (made of 304 stainless steel) was filled into the column. In order to minimize the unlavorable effect of wall flow, a liquid re-distributor was placed in the middle of packed bed. Besides the packed column, auxiliary equipments including air compressor, CO2 cylinder, gas mass flow meter with 1% accuracy (model CS200, Beijing Sevenstar Electronics Co., LTD), constant liquid-flow pump with 0.3% accuracy (model BTl-300, Shanghai Qi Te Analytical Instruments Co., LTD), thermostatic water bath with 1 K (model HHS-11-... 

In this paper, the mass transfer experiments of the absorption of CO2 in aqueous MEA and DETA solutions were carried out in a laboratory using randomly Dixon ring packed columns. The absorption performance was evaluated in terms of overall mass transfer coefficient Kqg ). The predictive correlation proposed by (Kohl and Nielsen, 1997) [4] for predicting the Kqo of MEA can be applied to a packed column containing a Dixon ring with an AAD of 14%. A new mass transfer correlation was successfully developed for predicting in DETA-CO2 absorption with an AAD of 16%. 

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