Space atmospheric distillation column

The catalytic reactions were carried out at atmospheric pressure in a conventional flow reactor using a U-shaped quartz tube (0 10 mm) with a fixed bed catalyst. The catalyst was diluted with quartz beads. CH4 and H2O were mixed with N2 in the ratio of 1/2/2. The flow rate of CH4 and N2 was controlled with a mass flow controller (STEC SEC-400 Mark3). Distilled water was fed into the reactor with a liquid pump (Shimadzu LC-lOADvp) through a vaporizer. The space velocity changed from 6.0 x 10 to 3.0 x 10 ml h g-cat . The products were analyzed by three on-line TCD gas chromatographs with Porapak-Q and Molecular Sieve 5A columns. 

Example 18.6. A sieve-plate column operating at atmospheric pressure is to produce nearly pure methanol from an aqueous feed containing 40 mole percent methanol. The distillate product rate is 5800 kg/h. (a) For a reflux ratio of 3.5 and a plate spacing of 18 in., calculate the allowable vapor velocity and the column diameter. b) Calculate the pressure drop per plate if each sieve tray is in, thick with j-in, holes on a -in. triangular spacing and a weir height of 2 in. (c) What is the froth height in the downcomer ... 

Another column excellent for fractionating small quantities of liquids at atmospheric pressure is the concentric tube column. This column is constructed from two precision bore tubes mounted concentrically with a very small annular space between them. During the distillation, the vapors and liquid move through this annular space and fractionation occurs. These columns are characterized by low throughput rate and a very low HETP and holdup. Some typical data for a 30.5-cm column, 6.5 mm in diameter, operated at a throughput rate of 1.2 ml per min, are an HETP of 0.36 cm (85 plates per column) with a holdup of only 0.018 ml per plate. These characteristics make this column ideal for the fractional distillation of a few milliliters of a liquid or for the purification of an analytical sample. 

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