INDUSTRIAL AND ENGINEERING CHEMISTRY
2628 t~
W,
= fraction of feed vaporized in the flash distillation = fraction of charge remaining in the pot, in a true boiling
point distillation of feed composition W L = fraction of charge remaining in the pot, in a true boiling point distillation of liquid product
W , = fraction of charge remaining in the pot, in a true boiling point distillation of vapor product z f ( a ) = composition distribution function for feed z( a) = composition distribution function for liquid product y( a) = composition distribution function for vapor product
Vol. 43, No. 11
LITERATURE CITED
(1) Bowman, J. R.,IND.ENG.CHEM.,41, 2004 (1949). (2) Ibid., 43,0000(1951). (3) Bowman, J. R.. and Edmister, W. C., paper presented before the Am. Inst. Chem. Engrs., Houston, Tex., 1950. (4) Bowman, J. R., and Edmiater, W. C., paper presented before the Am. Inst. Chem. Engrs., Minneapolis, Minn., 1950. RECEIVED June 28, 1950. Presented before the Division of Industrial and Engineering Chemistry a t the 116th Meeting of the AMERICAN CHEIICAL SOCIETY, Atlantic City, N. J.
Constant Pressure MercuryI
W. M. CAMPBELL’ UNIVERSITY OF ILLINOIS, URBANA, ILL.
In a research problem of the Fischer-Tropsch process it was necessary to collect a gas sample at constant pressure over a period of several hours. A mercury-sealed gasometer was the simplest apparatus, but a method had to be developed to compensate for pressure changes during the filling of the hell. The present paper deals with the method used. With a carefully constructed gasometer the gas pressure remained constant (within the accuracy of gas measurements) over the whole travel of the bell. This device could be used in any situation where a gas had to be collected slowly at constant pressure, and where mercury was the only sealing liquid which could be used.
and number of lengths of tubing are used, the gas pressure re. mains constant regardless of the amount of gas in the bell. To reduce friction, the pulleys and drum are provided with
CAS CONNECTION --CORD
+CORD
I
N THE study of reaction kinetics with a flow system, it is often necessary t o collect the product gases continuously over extended periods. A floating bell gasometer is convenient for this purpose. If the flow ratcs are to be kept constant, however, the gasometer must provide a constant back pressure, regardless of the position of the bell. With mercury as the sealing liquid this presents a problem, which is overcome by the device shown in Figure 1. The gasometer tank was constructed from a 5.5-inch length of 4-inch standard iron pipe, to which a base plate and inner inverted bell were welded. The floating bell was made by cutting the bottom from a Xo. 2l/2 fruit can, dissolving off the tin, lacquering the joints, and clamping a ring on the center of the top. A bell made in this way has a very thin wall, which makes the pressure compensation easier. The weight on the top of the bell and the fixed counterweight connccted to it by the counterbalancing cord are adjusted to give the desired pressure in the gas space. To maintain this pressure constantly, the counterbalancing cord is wrapped around a drum 1.5 inches in diameter and 3.75 inches long, on which several lengths of thin rubber tubing filled with mercury are wrapped. As the bell rises, this mercury-filled tubing unwinds and provides a greater tension on the balancing cord. When the correct size
* Present address, National Research Counoil, Chalk River, Ontario, Can.
COMPENSATOR
+MERCURY
-
Figure 1. Constant Pressure Mercury-Sealed Gasometer
needle bearings. To make these, phonograph needles are sol, dered into the ends of the drum and into the pulleys. The needlec are then rested in cone-shaped depressions in the ends of adjustable brass screws. RECEIVED M a y 31, 1951.
