INDUSTRIAL AND ENGINEERING CHEMISTRY BIBLIOGRAPHY
Adam, N. K., and Dyer, J. W. W., J . Chem. SOC.,127, 70-3 (1925). Adams, R. I., and Marvel, C. S., Univ.IZZ. BUZZ.20, (8) 54 (1922). Adkins, H., and Folkers, K., J . Am. Chem. SOC.,53, 1095-7 (1931). Ibid., 54, 1145-54 (1932). Allen, C. F. H., Ora. Smthesis. 20, 67-70 (1940). American Instrument Co., Catalogue 41, 59 (1941). Arnold, H. R., and Lazier, W. A., U. 8. Patent 2,116,552 (May 10. 1938). Bachmann, W. E., J . Am. Chem. S O ~55,1179-88 ., (1933). Ibid., 55, 2827-30 (1933). Ibia., 56, 963-5 (1934). Baur. F. J., Jr., and Brown, J. B., Ibid.. 67,1899-1900 (1945). Bent. H. E.. and Keevil. N. B.. Ibid.. 58. 1367-71 (1936). Blatt, A. H., “Organic Syntheses”, Vol. 11, p, 154, New York, John Wiley & Sons, Inc., 1943. Ibid., Vol. 11,p. 317. Ibid., Vol. 11, p. 372. Bohme, H. T.,A.-G., Brit. Patents 346,237 (Sept. 23, 1929), 358,721 (Nov. 27, 1929), and 359,188 (Dec. 9, 1929); French Patent 703,844 (Oct. 18, 1930); German Patents 568,628 (May 8, 1929), 577,037 (May 31, 1933), and 591,057 (Jan. 16, 1934). Bouveault, L., and Blanc, G., Compt. rend., 136, 1676-8 (1903), 137, 60-2, 328-9 (1903); Bull. SOC. chim., 131 31, 666-72, 1203-6 (1904); French Patent 338,895 (Jan. 27, 1903); German Patent 164,294 (July 5, 1903); U. S. Patent 868,252 (Oct. 15, 1907). Bowden, S. T., and John, T.,J. Chem. SOC.,1940,213-16. Burton, H., and Ingold, C. K., Ibid., 1929,2022-37. Campbell, K. N., and Campbell, B. K., Chem. Revs., 31, 77-175 (1942): Carbide and Carbon Chemicals Corp., “Synthetic Organic Chemicals”, 12th ed., p. 10 (1945). Carothers, W. H., Hill, J. W., Kirby, J. E., and Jacobson, R. A., J . Am. Chem. SOC.,52,5279-88 (1930). Chablay, M. E., and Haller, M. A., Compt. rend., 156, 1020-2 (1913). Chuit, P., Helv. Chim. Acta, 9, 264-78 (1926). Chuit, P., Boelsing, F., Hausser, J., and Malet, G., Ibid., 10, 113-32 (1927). Eclime Air Brush Co... Inc... “Pneumix Air Motored Stirrers”, p . i 2 (1943). Favorsky, A. E., and Nazarov, I. N., Bull. SOC. chim., [5] 1, 4665 (1934). Fenwal, Inc., “Thermoswitches”, p. 22 (1944). Fischer and Porter Co., “Special Service Rotameters”, Section 32E, p. 3207 (1946).
--.
(14) (15) (16)
(17)
(18) (19) (20) (21) (22) (23) (24) (25)
. ,
(26) (27)
(28) (29)
Vol. 39, No. 1
(30) Franke, A., and Kienberger, O., Monatsh., 33, 1189-1203 (1912). (31) Hafner, P. G., Swinney, R. H., and West, E. S., J . Biol. Chsm., 116, 691-7 (1936). (32) Hansley, V. L., J . Am. Chem. SOC.,57,2303-5 (1935). (33) Hansley, V. L., U. S. Patent 2,096,936 (Oct. 19, 1937). (34) Ibid., 2,158,071 (May 16, 1939). (35) Henke, C. O., and Benner, R. G., Ibid., 2,070,597 (Feb. 16, 1937). (36) Henke, C. O., and Prahl, M. A., Ibid., 2,021,100 (Nov. 12, 1935). (37) Hercules Powder Co., “Hercolyn and Abalyn”, pp. 2-6 (1943). (38) Hilditch, T. P., “Chemical Constitution of Natural Fats”, New York, John Wiley & Sons, Inc., 1940. (39) Karrer, P., “Organic Chemistry”, p. 241, New York, Nordeman Pub. Co., Inc., 1938. (40) Ibid., p. 606. (41) Kawai. Shin-ichi. J. Chem. SOC.Jaoan. 49.227-34 (1928). (42j Kharasch, M. S.; Sternfeld, E., and Mayo, F. R., .J. Am. Chem. Soc., 61, 215 (1939). (43) Kharasch, M. S., Sternfeld, E., and Mayo, F. R., J . Org. Chem., 5,362-78 (1940). Larcher, A. W., U. 8. Patent 1,963,997(June 26, 1934). Lazier, W. A., Ibid., 1,839,974 (Jan. 5, 1932). Levene, P. A., and Allen, C. H., J . Biol. Chem., 27,433-62 (1916). Levene, P. A., and Cretcher, L. H., Jr., Ibid., 33, 505-12 (1918). McElvctin, S. M., J . Am. C h m . Soc., 51, 3124-30 (1929). Marvel, C. S., and Tanenbaum, A. L., Ibid., 44,2645-50 (1922). Meyer, J. D., and Reid, E. E., Ibid., 55,1574-84 (1933). Nazarov, I. N., Compt. rend. acad. sci. U.R.S.S., 1, 325-8 (1934). Ibid., 4, 288-91 (1934). Normann, W., U. 9. Patent 2,242,017 (May 13, 1941). Oronite Chemical Co., “Naphthenic Acids”, p. 4 (1945). Prins, H. J., Rec. trav. chim., 42, 1050-2 (1923). Rosser, R. J., and Swann, H., U. 8. Patent 2,070,318 (Feb. 9, 1937). Ruzicka, L., and Meyer, J., Helv. Chim. Acta, 5, 581-93 (1922). Sauer, J., and Adkins, H., J. Am. Chem. Sac., 59,l-3 (1937). Schrauth, W., German Patent 636,681 (Oct. 15,1936). Schrauth, W., Schenck, O., and Stickdorn, K., Ber., 64, 1314-18 (1931). Scott, N. D., and Hansley. V. L., U. S. Patent 2,019,022 (Oct. 29, 1935). Ibid., 2,113,243 (Apr. 6, 1938). Shell Chemical Co., “Organic Chemicals”, 2nd ed., p. 8 (1942). Shell, J. M., and’McElvain, S. M., J . Am. Chem. Soc., 53, 750-60 (1931). Taylor, E. R., and Clarke, H. T., Ibid., 49,2829-31 (1927). Wiemann, J., Compt. rend., 212, 764-5 (1941). Wooster, C. B., and Ryan, J. F., J . Am. Chem. Soc., 56, 1133-6 (1934). Zuffanti, S., J . Chem. Education. 22, 230-4 (1945).
Heat Transfer Coefficients for
Condensing Hydrocarbon Vapors DANIEL A. DONOHUE The L u m m u s C o m p a n y , New York, N. Y .
T
HE theoretically derived Nusselt relations (6) for calculating the heat transfer coefficient of condensation on horizontal tubes are used for designing commercial condensers. The relations are in two forms; the first is in terms of temperature difference At: h, 0.725 (kj’pj’gX/Npj AtD)‘” (1) and the second is in terms of condensate loading w / L : h, = 0.955(@ap,2gL//.y~)1’a (2) where D = outside tube diameter, feet g = acceleration of ravity = 4.17 X 108 ft./hr.2 h, = mean value of &e coefficient of heat transfer for the entire tube bundle, B.t.u./(hr.)(sq. ft.)( O F.) kj = thermal conductivit of condensate a t average film temperature, g.t.u./(hr.)(sq. ft.)( O F.)/ft.
L = horizontal tube length, feet N = number of tube rows in a vertical condensing stream = average film temp. = [condensing vapor temp.
w At X pi
pj
+
(tube wall temp.)/2], O F. = rate of flow of condensate from lowest point on condensing surface, lb./hr. = temperature difference between t h e dew point of the condensing vapor and the outer tube wall temperature, O F. = latent heat of condensation a t saturation temperature, B.t.u./lb. = viscosity of condensate a t average film temperature; lb./(hr.) (ft.) = density of condensate a t average film temperature, lb./cu. ft.
January 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
Several charts ( 1 , 8, 7 ) essaying rapid solution of the above equations have been presented. However, it should be pointed out that charts devised to solve Equation 1, which require substitution of the value of temperature difference At, are not desirable for design use, because At is not readily known and must be determined by trial and error, and this necessitates more than one solution of the problem. On the other hand, Equation 2 requires substitution of the value for condensate loading w/L and, since this value is known a t the outset, only one solution is necessary. Therefore Equation 2 is the relation suitable for condenser design. Constant values for the term 0.955 (klSp/*g/pf)l'* were observed for hydrocarbons and for petroleum fractions over the usual condensing temperature range. For this commercially important case the heat transfer coefficient may be expressed as
h, = C(L/w)'Ia
A simplified.form of theNusselt equation Itm
CONSTANCY O F PHYSICAL PROPERTIES
It was noted for pure hydrocarbons and for petroleum fractions that, as the result of the fortuitous combination of physical properties, the value of the term 0.955 (Jclsp/zg/pi)lI s remained constant within 10% throughout the temperature range for each individual compound. Table I lists calculated values of this term for the paraffin hydrocarbons shown throughout the indicated temperatxre range. Viscosity values from 11700&0 Driclmmer and Bradford (S), density values from Nelson (4), and thermal conductivity values from ,Smith (8) were 3 used; since measurements of thermal conductivities are available only over the range 68" to 212" F., values at other temperatures were obtained by extrapoIO$Ofo 7 400 lation. Table I1 lists calculated values of 0.9551 (kf3pj2g/pf)1 1 3 for three typical zo 0 petroleum fractions throughout the indicated temperature range. Viscosity values from Nelson ( 6 ) , density values from Nelson (4, and thermal conductivity values from Smith (8) were used.
SIMPLIFIED CONDENSATION EQUATION
Referring to Equation 3, C represents the average value of 0.955 ( k / s m z g / p j ) for each compound listed in Tables I and 11. The value of C for pentane and for the 76.5" A.P.I. natural gasoline is 775. For these compounds Equation 3 becomes
h, = 775(L/w)1'8
(4)
A chart which may be used for solving this equation is given in Figure 1; to use it, w/L must be known, or, if L is 16 feet, only w need be known. Using Equation 4 or Figure 1 as a basis, heat transfer coefficients for the other compounds can be obtained by multiplying by the following factors: Vapor Compn. CS
Chart Multiplier 1.0 0.95 0.93 0.87 0.86 0.83 1.0 0.9 0.88
CS C8
ClO c 1 2 c 1 4
Light gasoline Gasoline Kerosene
ADAPTATION TO DESIGN
An experimental investigation of a small tube bank (9) indicates the suitability of the Nusselt relation for design use. This relation is applicable only to streamline flow of condensate on the tubes, Reynolds number less than 2100; but on horizontal tubes condensate flow rarely exceeds this value. The Reynolds number for horizontal tubes is
NR. where D,
G
=
D6G/i.i
=
2w/pfL
(5)
= equivalent diameter of flow area, feet = mass velocity, lb./(hr.)(sq. ft.)
N R= ~ Reynolds number
To determine w the total flow of condensate is divided by the number of vertical condensing streams. For the case of a tube bundle having a rectangular cross section, the number of vertical condensing streams would be equal to the number of tubes in a
tf
50
h =z coefficient of heat transfer = %.t.u.J (hr.)(sq. ft.) (" F.) Z =: tube length, feet W =I maximum condensate flow in a vertical stream, lb./(hr.) (tube)
= C(L/w)'Js
is presented for calculating heat transfer coefficients for hydrocarbon vapors condensing on horizontal tubes. This simplification results from the observation that the term 0.955(k&j2g/pf)* l 3 in the Nusselt equation is approximately constant aver the usual condensing temperature range for the hydrocarbons considered. Since solution requires that only the condensate loading w / L be known, the necessity for looking up values of the physical properties k f , pf, and pf at the pertinent film temperature is obviated; this results in an easy, direct, time-saving method. Application of this equation to coinmercial design is illustrated.
(3)
wherein the constant C, which equals 0.955 (k&zg/i.r)1/3, is characteristic of the compound. Equation 3 is the simplest and most facile means of solution of the condensation equation yet developed, since the only required quantity is condensate loadipg w/L,which is immediately available, and search to obtain the values of the physical properties kf, pf, and pj at the appropriate film temperature is unnecessary. The superiority of Equation 3 as a ready means of calculating heat transfer coefficientsfor condensing hydrocarbons becomes apparent by comparison with the references listed (1, 2, '7).
Figure 1. Condensation of Hydrocarbon Vapors on Horizontal Tube Banks
63
100
150 200 250 300 350 400 450 500
TABLE I. VALUESOF C IN EQUATION 3 CS cs cs ClO Cl2 780 780 780 764 748 738
... ... ...
...
728 746 755 763 741 728 713 681
668 698 713 733 728 713 678
...
...
...
... ...
... 625
662 679 695 687 662 643 641
.*.
...
609 650 667 672 675 678 645 625
c 1 4
... ... ... 607 625 652 655 654 649 636
INDUSTRIAL AND ENGINEERING CHEMISTRY
64
TABLB11. VALUESOF C IN EQUATION 3 ti 60 100
150 200 250 300 350 400 460 500
76.5’ A.P.1, Natural Gasoline 727 762 785 806
... ... ...
... .*. ...
57‘ A.P.I. Gasohne
...
667 696 699 704 702
... ..* ... ...
*
42’ A.P.I. Kerosene
... ...
621 664 676 684 675 665 652 628
horizontal row if an “in line” tube spacing were used; if a staggered arrangement were used, it would be twice this number. In practice tube bundles of circular cross section are used; to resolve into a square bundle, the number of tubes a t the horizontal diameter is multiplied by 0.886 when the pitch is in line and by 1.77 when staggered pitch is used. For example, a shell-and-tube condenser was used to condense 43,000 pounds per hour of pentane vapor a t 140” F. under an operating pressure of 15 pounds per square inch gage. The unit used was a shell of 28-inch outside diameter having 580 a/,-inch
Vol. 39, No. 1
OD tubes on lS/,G-inch triangular pitch, 16 feet long. The number of tubes at the horizontal diameter was 27, and the average number of vertical condensing streams was 1.77 X 27 = 48. w = 43,000/48 = 896 and a value of h, = 203 is read from Figure 1. The Reynolds number may be calculated from Equation 5
N R= ~ 2w/,u,L
2 X 896/0.436 X 16 = 258
which shows that the condensate was in streamline flow. LITERATURE CITED
(1) Benenati, R. F.,and Othmer, D. F., Chem. & Met. Eng., 51, No. ’ 5 , 107-8 (1944). (2) Chilton, T. H., Colburn, A. P., Genereaux, R. P., and Vernon, H . C.. Trans. Am. SOC.Mech. Enars.. 55. 7-14 (1933). (3) Drickamer, H.G.,and Bradford, J: R.’,Trans. A b . Inst. Chem. Engrs., 39,325 (1943). (4) Nelson, W . L.,Oil Gas J., 36,No. 37, 184 (1938). (5) Nelson, W.L., “Petroleum Refinery Engineering”, 2nd ed., p. 125, (1941). (6) Nusselt, W., 2. Ver. deut. Ing., 60,541,569 (1916). (7) Peck, R. F., and Bromley, L. A., IND.ENG.CHBY., 36, 312-16 (1944). (8) Smith, J. F.D., Trans. Am. SOC.Mech. Engrs., 58,719-26(1936). (9) Young, F. L., and Wohlenberg, W. J., Ibid., 64,787-94 (1942).
Vulcanization of GR-S with Halogen Compounds B. M. STURGIS, A. A. BAUM, AND J. H. TREPAGNIER E. I . d u Pont de Nemours and Company, Inc., Wilmington, Del.
A
new class of nonsulfur vulcanizing agents for butadiene-styrene copolymer rubbers consists of halogenated compounds which may be divided into three types: ( a ) halogenated aliphatic hydrocarbons containing at least one -CXa group, where X represents chlorine, bromine, or iodine; ( b ) halogenated aryl methyl compounds containing at least one halogen in the methyl group; and ( c ) aliphatic compounds containing a -CXs group and another reactive group, such as ethyl trichloroacetate. Each type behaves somewhat differently with respect to activation by metal oxides and other substances, but all give vulcanizates with high moduli and good physical properties. These vulcanizing agents are of particular interest since they produce vulcanizates having unusually good aging properties at elevated temperatures, The mechanism of vulcanization with these halogenated vulcanizing agents is discussed.
F
OR more than a hundred years sulfur has been used almost
exclusively to vulcanize rubber into articles of commerce. With the advent of the butadiene copolymer rubbers, compounders naturally turned t o the time-tested combinations of sulfur, metal oxide, and accelerator to provide a means of vulcanizing these new elastomers. I n general, these combinations have worked out quite well, although certain of the properties of the synthetic rubber vulcanizates have never been made to equal those of natural rubber. Profound changes in physical properties during aging a t elevated temperatures, for example, have always characterized GR-Svulcanizates and have impaired their suitability for many uses. At various times investigators have sought t o vulcanize rubber by other means, both for the purpose of obtaining new and superior vulcanizate properties and in an attempt to shed some light on the process of vulcanization. As a result a variety of
chemical compounds, such as benzoyl peroxide (il),-diazoaminodichloroazodicarbonamidine I), (d), quinones (3,4, benzenes (5, & I d ) , quinone oximes and imines (€9, polynitrobenzenes (IO),and mixtures of aromatic amines or phenols with oxidizing agents, have been found to vulcanize rubber. These compounds can be classified as (a) compounds which decompose thermally a t vulcanizing temperatures to yield free radicals, (b) oxidants of appropriate resonance structure, and (c) agents which yield free radicals on oxidation (1). None of these agents, however, has produced rubber vulcanizates with properties equal to those obtained with sulfur. These nonsulfur vulcanizing agents have dl been tried, with more or less success, as vulcanizing agents for GR-S. Some of them, such as benzoyl peroxide, vulcanize only feebly ( I ) ; others, such as the polynitrobenzenes, give quite good vulcanizates (IS). As in the case of rubber, however, none has proved of sufficient merit to be used commercially. I n the search for new types of compounds which might vulcanize GR-S to give superior properties, especially resistance t o heat aging, a large new class of vulcanizing agents has been discovered of a type which was not readily predicted from the various vulcanization theories. This class is composed of certain types of halogenated organic compounds and is unique in that its membere will not vulcanize natural rubber. These vulcanizing agents may be divided into three subclasses as follows: 1. Chlorinated aryl methyl compounds containing at least one chlorine substituted in the methyl group-for example, benzal chlori’de and o-chlorobenzotrichloride. 2. Halogenated aliphatic hydrocarbons containing at least one -CX1 group, in which X represents chlorine, bromine, or i odine-for example, hexachloroethane and 1,1,1,3-tetrachloropropane. 3. Aliphatic compounds containing a trichloromethyl group attached to a strong polar grou for example, trichloroacetic acid and trichloromethane sulfoctgide.
