December, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
IO
1321
per gram of air, ozonizer efficiency is no longer dependent on absolute humidity. Table I (runs 103-113) shows the conditions under which such tests were made, and Figure 4 illustrates the results obtained. It is evident that relative humidity does not effect ozonizer efficiency; in future tests involving temperature variations, only absolute humidity must be controlled.
9
ACCURACY OF TEST DATA 7
Several experimental procedures were tried and discarded before the procedure described wa8 chosen. I n spite of the obvious failure to account for noncorrection of the gas laws in Equation 1 and the possibility of supersaturation in the humidity controlling traps, the method gave reproducible results throughout a series of ninety runs. The procedure was checked by actually freezing out the water in a liquid nitrogen trap and weighing the amount of water found in a measured quantity of air. The results showed that less than 5% error was experienced by relying on the equation and method, if not less than four cold traps in series were used. If' care waa taken to keep the traps from filling with water or ice, the error remained fairly constant and, because the determination was concerned with only comparative results and not absolute yield values, the method was considered sufficiently accurate for the determination of the effect of water vapor on ozonizer efficiency.
'> -E
0
3
% 4
w
a w 3
2
CONCLUSION
The general effect of water vapor on ozonizer efficiency has been known by practically all designers of ozone equipment, and large installations usually include air drying provisions. This paper provides curves illustrating the effect of absolute humidity over a large range of humidities, to enable the engineer to predict in advance how much drying will be required for ozone equipment. It has been shown that variance in generating capacity and current density does not materially affect the shape of the curves. Relative humidity does not influence ozonizer efficiency and may be disregarded if absolute humidity is controlled.
I
Mq Os/ Hr.
1
100
Figure 4. Influence of Relative Humidity on Ozonizer Yields Data from run8 103-113
water per gram of air and corresponds to a dew point of approximately -17" C. From a practical standpoint, therefore, the air used in industrial ozonizers shduld be dried to a dew point of -17" C. for highest efficiency. Greater absolute humidities result in greatly decreased efficiencies, as shown by the sharp slope of the curves above 0.001gram of water per gram of air. EFFECT OF RELATIVE HUMIDITY ON YIELD AT LOW ABSOLUTE HUMIDITIES
I
It was of interest to determine whether relative humidity would effect ozonizer efficiency, because, in later tests to be made on temperature influence,, if the relative humidity effect were unknown it would make interpretation of results difficult by introducing two variables. I n order to study the effect of relative humidity, the tests must be made with ozonizer temperature constant and with absolute humidity either constant or noneffective. Figure 3 shows that, below an absolute humidity of 0.001 gram of water
TABLEI. CONDITIONE FOR TESTRUNS Runs Primary volts Primary amperes Secondary volts Secondary amperes Generating area,.sq. in. 0 aoniser constant temp.,,
24-78 118.0 0.810
c.
6000.0 0.006 260.0 20.5
76-83 118.0 0.310 8000.0
86-101 118.0 0.800
210.0 10.0
210.0
0.005
6000.0 0.005
5.1
103-113 118.0 0.310 6000.0 0.008
210.0
-56.0
LITERATURE CITED
(1) Armour Research Foundation, Chern.Eng. News,22, 2101 (1944). (2) Dawson, W.J., Ry. EEec.Engr., 31, 251-9 (1940). (3) Ewell, A. W., Ref&. Eng., 27, 131 (1934). (4) Forbes, G. S., and Heidt, L. J., J. Ana. Chem. SOC., 56, 1671-6 (1934). (5) Keyes, F. G.,and Smith, L. B., Refrig. Eng., 27, 127-30 (1934). (6) Thorp, C.E., C h m . Eng. News, 19, 686 (1941). (7) Ibid., IND.ENQ.CHEY.,ANAL.ED., 12, 209 (1940). (8) Warburg, E., and Leithauser, Ann. Physik, 20,743 (1906); 23, 209 (1907).
Viscosity of Pine Gum-Correction With reference to our article which appeared in the May, 1946, issue (page 555), our attention has been called to an article entitled "Production of Clean Gum Rosin" by W. C. Smith in INDUSTRIAL AND ENGINEERING CHEMISTRY, Volume 26, pagee 408-13 (1936). On page 411 of this article there are graphs showing the Engler visccsity of water-free long-leaf and slash pine gums of original turpentine content and these gums diluted to 30 and 40y0turpentine and covering temperature ranges up t o 100' C. We regret that through an unfortunate oversight we made no reference to Smith's article. W. J. RUNCKEL AND I. E. KNAPP NAVALSTORES RESEARCH DIVISION U. 8. DEPARTMENT OF AQRICVLTURE NEWORLlhNS, IJA.
