Automatic Laboratory Fractionating Column VICTOR C. SMITH,
ARTHUR L. GLASEBROOK', CHARLES R. BEGEMAN, AND WHEELER G. LOVELL
Research bboratorin Division, General Motors Corporation, Detroit, Mich. STILL POT AND HEAT CONlROL
A n automatic laboratory hactionrting column, one of a number used for some yean lor the analytical distillation 01 close-boiling hydrourbons, ir described in detail. It i s made almon entirely of cortosion-resistant metal, including a 10-foot vacuum jacket. The automatic features include control of heat input to the still pot, collection of the distillate in separate containers, and recording the volume of didillate and the distillation temperature. Adequate safety devices are provided. Using a modified removable Duhon packing, the column has 50-ml. holdup, 1200 ml. per hour throughput, and as high as 1 2 0 theoretical platn. Detailed drawings of the column i b d and of the electrical circuib for automatic control are included.
The still pots are made from polislied stainleu steel or Monel apheriral Uoats, 17.5 t o 22.5 cm. (7 to 9 inrhrs) in diameler, t u wliich Oangrd necks rn silver-soldered. The flange 13grooved fnr a roDDer Cmket and ran be bdtrd to the t,ottom of the column secure-&ai&t leaks. It is heated by an electric resistaoce element attachid directly to the bottom.^ To reduce the heat loss and make i t more constant, the entire still pot is surrounded by a lmeeed aluminum enclnsure. The details of the assemhlv are sh;b in Figure 3. The heat input to the pot is controlled by the presure drop across the column, or by the pressure in the still pot, since the usually operated atmospheric oressure. pressure. This columns are usuaUv ooerated rtt atmosnherio maintains a fairly "conitant constant rate of th6uihDut. thrauehDut. An inclined two-legged mercury manometer is used to &
