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I N D U S T R I A L A N D ENGINEERING CHEMISTRY
otherwise no heat balance could be obtained. This gives an accurate and easy method of operation control. Figure 6 is a similar diagrammatic sketch of another type, which operates on a slightly different principle. The gases enter at the left near the top and go through the pipes of heat exchangers 1, progressing downward, and arrive a t the bottom of the converter a little below 400' C. From there they pass upward through the adiabatic converters 2, and heat exchangers 1, to the air dilution converter 3, and finally out through the top heat exchanger. In the converter 3 they are cooled 6and diluted by auxiliary air entering through ducts 7 , and controlled by valves 8 and 9. Pmfl The prelimiBLOU€R nary adiabatic converters a n d heat exchangers o p e r a t e in t h e same way as the trays and coils in the previous conv e r t e r . More than one adiabatic converter will usually be necessary toFigure 6-Diagrammatic S k e t c h of an Air Dilugether with ..the tion Converter 1-Heat exchangers 6-By-pass valves corresponding 2-Adiabatic converters 7-Auxiliary air lines 3-Air dilution converter 8-Auxiliary air valves heat exchangers 4-Hollow perforated grids 9-Main auxiliary air in order that the 5-Contact mass valve temDerature mav be kept down and that equilibrium be not to; closely a i proached. On account of the air dilution occurring later in the process, the initial concentration of SO2 should be about 8 per cent. At conversions up to 12 per cent, and of the 02, about 70 per cent this higher concentration of SO2 partially compensates for the loss due to the lowered reaction rate resulting from too rich a mixture; but above this point the concentration becomes important and auxiliary air is necessary. Heat balances may be made on the various sections in exactly the same way as in the previous converter. A L typical set of conditions is shown below:
6p-J -
Initial SO2 = 12 per cent; 0 2 = 8 per cent Gases entering at bottom, 393" C. Gases leaving first adiabatic converter, 550" C., 45 per cent converted Gases entering second adiabatic converter, 463' C. Gases leaving second converter (adiabatic), 550' C., 70 per cent converted Gases entering heat exchanger below air dilution converter, o.?-lo
r. L.
Gases leaving this heat exchanger, 307" C . Gases leaving second heat exchanger, 393" C.
Reese' gives experimental results obtained from a threesection converter where cooling was obtained by radiation. Although the data are not complete, it will be noticed that the temperatures employed by him in converter practice are approximately those shown in Figure 3. The officers and executive committee of the Division of Chemistry and Chemical Technology of the National Research Council for the year 1925-1926 are: chairman, William J. Hale; vicechairman, s. C. Lind; executive committee, William J. Hale, S. C. Lind, William McPherson, H. S. Miner, James F. Norris, C. L. Reese, and E. W. Washburn.
Vol. 17, No. 6
A Vacuum Door' By Robert F. Mehl and Donald P. Smith PRINCETON UNIVERSITY. PRINCETON, N. J.
D U R I N G an ipvestigation upon the preparation of very pure alloysZ it became necessary to devise a piece of apparatus for rapidly and safely admitting a gas into a high vacuum system. The presence of stopcocks in such a system is a source of continual annoyance because of leaks, and the piece of apparatus described herein has eliminated this trouble. The tube A connects the apparatus to the system. While the system is being evacuated, the mercury in B is drawn up through tubes C and D. Tube D is a drawn-steel tube of about 4 mm. inside diameter, and is contained within C, a stout tube of 12 mm. inside diameter. D is centered in C by means of bent wires conveniently placed. When the evacuation of the system is complete the mercury in C and D is held a t barometric height above the mercury in B. C and D are about 80 cm. long; when at its highest the mercury in these tubes stands a short distance below bulb G. The gas to be admitted into r the system is led through tube E , which is given great freedom of motion by means of two Vshaped bends placed a t right angles. The constricted end of E is placed within the enlarged opening of tube I), and the gas, the flow of which is controlled by means of a reducing valve, is caused to flow in a slow, steady stream. The small bubbles of gas enter D and rise slowly, increasing in size as they rise. F , the end of the steel tube D, is plugged, and just below the plug the tube is drilled with about a dozen 2-mm. holes distributed a t random. As the bubbles rise they force ahead sections of mercury, which finally reach F. At this point the mercury and the gas discharge horizontally into the large bulb G. The gas enters the evacuated system through A and the mercury falls into C, which by virtue of its large diameter permits the mercury quickly to adjust its height in accordance with the new messure existing in the system. When the apparatus is running correctly, the mercury-gas lift works smoothly and continuously. A spasmodic action may be corrected by an adjustment of the reducing valve. H is an auxiliary tube, concentric to C and D, under which E is placed until the bubbling is correctly adjusted or until the cleansing system, placed between the reducing valve and E , is operating satisfactorily. D is made of steel instead of glass so that i t will not break during the slight jarring produced by the discharge of mercury and gas a t F. This arrangement also takes care of any change in pressure that might occur in the system, the gas escaping through B in the case of an increase in pressure, or the mercury rising in C and D in the case of a decrease in pressure. 1 2
Received March 5, 1925. Mehl, Trans. A m . Electrochem. SOL,Preprint, October, 1924.
