122nd NATIONAL ACS MEETING
DIVISION OF GAS AND FUEL CHEMISTRY
Electric Probe Developed for Analyzing Turbulent Flames • High-temperature aid to jet engines?
combustion
chambers—
• Active center theory describes many aspects of absorptive power of activated carbon • Annealing carbon black decreases modulus properties of compounded rubber "•"DEVELOPMENT of an electrical probe *~* which shows no response in a laminar flame b u t gives a signal in a flame where both ionization and turbulence are pres ent may be used to determine flame boundaries and degree of turbulence, and has a number of important industrial pos sibilities. T h e probe described b y G. A. J. Voetclink, Phillips Petroleum C o . , at the Symposium on Chemistry of Combustion, consists of a ceramic-tipped metal probeconnected to an amplifying circuit. This is the only type of flame-measuring instru ment which is insensitive to temperature, and it seems promising a s an indicator for control of blowout in jet engines and to prevent the flames from reaching the tur bine blades. Other applications may be in industrial safety devices on large burners, as a fire-detecting device in aircraft, and in analyzing combustion processes in in ternal combustion engines.
• High-Temperature
Combustors
Metal combustion chambers in jet en gines are limited in temperature resistance and t e n d to lower flame propagation rates and blowofF velocities. Attempting to de liberately reduce these difficulties, Alex ander Weir, Jr., of Michigan University's Aircraft Propulsion Laboratory, has de veloped experimentally a simple ceramiclined tube which performs favorably and has been operated at temperatures in ex cess of 3000° C. Hydrocarbon-Air Combustion. The symposium was a natural followup to a similar program on theoretical aspects of combustion held jointly with t h e Division of Physical and Inorganic Chemistry at the New York meeting in September 1951. Five papers presented b y members of t h e NACA Lewis Flight Propulsion Labora tory summarized results of a program of determining fundamental data on combus tion of hydrocarbon-air mixtures. Some of the general conclusions were that flan ιinability limits of hydrocarbon-air mix tures can b e predicted within an average deviation of 6 % ; all variations of condi tions in burning benzene-air mixtures which tend to replace exhaust gases around
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the outer cone with air or to increase dif fusion of oxygen into the outer cone, en hance burning properties and decrease smoking tendencies; slow oxidation of b o t h ethane and propane can be induced w i A free methyl radicals from t h e dissociation by light of either azomethane or acetone.
• Active Centers Depict Adsorptive Powers T i m e of activation, type of oxidizing giis used, temperature, and presence of mineral substances are all important condi tions affecting the specific adsorptive powers of activated carbons. T h e pore theory, explained J o h n \V. Hassler, W e s t Virginia Pulp a n d Paper Co., does not satisfactorily account for some variations in adsorptive power. Although the evi dence is entirely circumstantial, Mr. Has sler thinks that the active center theory provides a convenient method for describ ing many aspects of specific adsorptive powers. This theory assumes that adsorp tion occurs only on specific areas, or ac tive centers, on the carbon surface, that t h e carbon atoms in these centers a r e ar ranged in distinctive patterns each with specific adsorptive power, and that activa tion conditions determine t h e types of ac tive centers. Increasing improvements in manufacturing tailor-made activated car bons, h e said, arc allowing production of carbons with equal adsorptive powers, or with emphasized adsorptive powers for particular substances.
• Property Improvement By Carbon Annealing Just like steels, carbon blacks have had their properties improved by annealing. Such treatment over a temperature range of 1000° t o 3000° C. was reported b y W . R. Smith of Godfrey L. Cabot. Property improvement of carbon blacks is always of marked interest to t h e rubber industry, and preliminary tests in compounding rubber with these blacks indicate a marked de crease in modulus properties, b u t a very small loss in resistance to abrasive wear.
Fundamental Carbon Studies. Results CHEMICAL
of several fundamental studies of the prop erties of carbon w e r e presented b y workers at Perm State with C. C. Wright, Penn State, who was also symposium chairman. Variation in time of preheating gas-baked carbon or graphite with helium or argon was shown to have negligible effect on subscciuent reaction rates of t h e carbons with carbon dioxide during the constant rate period. Variation of the nitrogen pre heat time on the other hand, according to data presented b y P. L . Walker, Jr., de creased t h e reaction rates. Changes of interlayer spacing of artificial graphite were shown b y I I . A. McKinstry to be practically linear with temperature change. Changes in interlayer binding have in significant effect on carbon gasification rates. Coal Chemistry Investigations. Humic acids continue to occupy the attention of a number of investigators. Successful ap plication of polarography to study of coal oxidation products was found by A. F. Cody, Penn State, to confirm results pre viously obtained by other methods. Dis tinct and separated w a v : s obtained by S. R. Milliken, also of Penn State, for products of the different oxidation meth ods, indicate that polarography has gen eral applicability in studying t h e composi tion of humic acids from coal. I n the same group of studies II. L. Lovcll has investi gated the actioii of ultraviolet light on humic acids a n d has shown t h a t some of the materials produced are sublimablc, in dicating the possibility of using the mas* spectrometer as an aid in further studies. From a less optimistic viewpoint, G. R Yohe, Illinois State Geological Survey, ha* conducted work indicating that the coa' humic acids may not b e as rich a source of information on the chemistry of coal a? has been previously assumed. Dr. Yohc bases his conclusions on the oxidation ol a number of alkyl-substituted phenols anc the two naphthols under conditions similai to coal oxidations. T h e nature of the prod nets causes some doubt to be cast on th< theory that reactions producing humi< acids are entirely degradative, and sug gests that they may well include new link ages formed during oxidation. Ignition Acceleration by Ammoniun Nitrate. Use of 4% of a 5N ammoniun nitrate solution emulsified in fuel oil as ai ignition accelerator was reported by I. Cor net, University of California. Appreciable shortening in ignition delay time result* he said, outlining experiments with a CF1 Diesel engine. Mr. Cornet suggested tha the use of water as a coolant in the forn of a n aqueous emulsion fuel has not beei reported before and that this might hav limited application in such equipment a gas-turbine powered patrol boats. Mucl interest was shown in this prescntatior but doubts w e r e raised concerning coi rosion problems, effect of water on fuc quality, and emulsion stability. Previou related work done by others h a s met wit little success.
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ENGINEERING
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