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BRIEFS
u u u u u Reynolds number of the oxygen flow in the viscous region, and the rate of increase of the flame height decreases with the onset of the turbulent region. The flame height also decreases with an increase in the mass velocity ratio of oxygen and hydrogen. The combustion efficiency is greater than 99.98%, and the operation is smooth and free of any explosion. Such a burner with hydrogen velocity of 300 feet per second and a mass velocity ratio of oxygen to hydrogen of 5 has been designed for 10 normal cubic meters of hydrogen per hour and has been in trouble-free operation for more than 1000 hours.
Dipak Gufita, P. G. Deshfiande, and S. N . Bashyam, Chemical Engineering Division, Atomic Energy Establishment, Trombay, Bombay, India IND.ENG.CHEM.,PROCESS DESIGN DEVELOP. 3,70-73 (1964) KINETICS OF CATALYTlC XYLENE HYDRODEALKYLATION
Catalytic xylene hydrodealkylation proceeds in two steps : xylene to toluene, then toluene to benzene. The consecutive reactions are both characterized as first-order with respect to the aromatic and half-order in hydrogen. Xylene demethylates much more readily than toluene, and the rate constants relative to toluene determined for use in reactor sizing are: o-xylene, 4.6; rn-xylene, 2.6; $-xylene, 2.4; ethylbenzene, 2.2; and grouped isomers 2.7. Benzene-toluene-xylene distribution relationships have been derived which are dependent only on charge stock composition and independent of operating conditions. Xylene conversion will normally be in the 90 to 99 mole % range in practical applications. Operations are sirnilat to the Houdry Detol process for toluene demethylation in that the same catalyst and similar operating conditions apply. Hydrogen consumption and temperature rise are higher than for toluene because of the two methyl groups.
A. H. Weiss and L. C. Doelfi, Houdry Process @ Chemical Co., Linwood, Pa. IND.ENG.CHEM.,PROCESS DESIGN DEVELOP. 3,73-78 (1964)
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KINETICS OF THERMAL DEALKYLATION OF ALKYLNAPHTHALENES
The thermal dealkylation of 1-methylnaphthalene, 2-methylnaphthalene, 1,6-dimethylnaphthalene,and 2,3,6-trimethyinaphthalene with hydrogen a t 611 O to 688' C., 300 to 900 p.s.i.a., and hydrogen-alkylnaphthalene feed mole ratios of 2.2 to 7.9 indicates a first-order mechanism with respect to alkylnaphthalenes and half-order with respect to hydrogen. The reactions of l-methylnaphthalene and 2-methylnaphthalene to form naphthalene appear reversible, while the reactions of trimethylnaphthalene to form dimethylnaphthalene and dimethylnaphthalene to form monomethylnaphthalene appear to go to completion with no noticeable equilibrium. A possible reaction mechanism has been proposed, from which rate equations for the principal reactions involved have been derived.
John C. Bixel, Lavaun S. Merrill, Jr., V. Dean Allred, and Alvin L. Benham, Marathon Oil Co., Littleton, Colo. IND.ENG.CHEM.,PROCESS DESIGN DEVELOP. 3,78-84 (1964) FUNDAMENTAL STUDIES O N ANODIC PROTECTION. ALLOY 20 IN SULFURIC ACID
The anodic polarization behavior of Alloy 20 in sulfuric acid was investigated by potentiostatic techniques, and the effect of acid concentration and temperature on the shape and relative position of the anodic polarization curve with reference to the current and potential coordinates was evaluated. Acid concentrations from 3 to 96% H2SO4 were used in the temperature range 20" to 127' C. An increase in acid concentration up to 6470 H&Od displaces the polarization curve toward more cathodic potentials and higher current densities. An increase in temperature results in higher current densities and slightly more cathodic potentials. Particular emphasis was placed on the interpretation from an engineering viewpoint of the anodic polarization parameters, such as critical current, passive current, etc., as affected by changing acid concentration and temperature. Z. A. Foroulis, ESSO Research and Engineering Go., Madison, N . J. IND.ENG.CHEM.,PROCESS DESIGN DEVELOP. 3 , 8 4 8 8 (1964)
MAGNEHELIC@ ESSURE GAGES give d e a d read o u t - n o t a p p i n g n e c e s s a r y In MAGNEHELIC gages, magnetic linkage is used in place of troublesome mechanical linkages for exceptionally responsive, consistently accurate indication of differential pressures in air and non-corrosive gases. Pointer movement is inertiafree and drift-free. There is virtually no hysteresis. Highly resistant to shock and vibration. Choice of 30 standard ranges from 0-0.5" water to 0-5 psi in a single case size. Full details in Bulletin A-20 available on request. WRITE FOR BULLETIN A - 2 0
P. 0. BOX 373-J Circle
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A.363
MICHIGAN CITY, INDIANA
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VOL. 5 6
NO. 1
JANUARY 1964
71
