852
T H E J O V R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
Vol.
12,
NO. 9
8-Harries, J. Gasbel., 1894, 82; Luggin, I b i d , 1898, 713; Boudouard, considerable interest in the German plants,*’ and probAnn. chim. phys., 24 (1901), 1; Hahn, 2 physik. Chem., 44 (1900). 510; ably a large amount of t h e capital cost and all of the Ibid., 48 (19041, 735; Farup, I b d , 50 (1906), 276; Meyer and Jacobi. experimental cost has been written off as a war ex- J . Gasbel., 62 (1909), 282, 305; Clement, Bureau of Mines, Bulletin 7 (191 1) ; Haber, “Thermodynamics of Technical Gas-Reactions” (Longpenditure. mans, Green & Co., 1908). Conditions in America are somewhat less favorable 9-B. A. S. F., Brit, Patent 27,955 (1912); D. R. P. 292,615 (1912); for the private operation of a Haber-Bosch plant t h a n D. R. P. 293,943 (1913); Fr. Patent 469,907 (1913); Brit. Patent 16,494. Brit. Patent 11,878 (1910); General Chemical Co. (deJahn), in Germany because of higher labor costs and greater Brit. 10-Lane, Patent 124,761 (1918); Greenwood, “Industrial Gases.” installation charges. The determining factors may ll-Soci6t6 1’Air Liquide, Brit. Patent 15 053 (1914). Compt. rend., 94 (1882), 1355; Bohr and Bock, 12-Wroblewski, depend on the development of methods of utilization . Ann. P h y s . [2], 44 (1891), 318. of the ammonia and by-products, which in t u r n may W i d13-C. Bosch, 2. Electrochem., 24 (1918), 361. involve combinations with other known processes. 14-B. A. S. F., Brit. Patent 1,759 (1912); U. S . Patents 1,126,371 I n the German plants the combination of the ammonia- (1915); 1,333,087 (1915); D. R. P. 254,043 (1911); D. R. P. 279,954 (1913). 15-F. A. Weber, “The Action of Carbon Monoxide on Caustic Soda,” soda with t h e direct synthetic ammonia process has Dissertation, Karlsruhe, 1908; G. R. Fonda, “The Action of Carbon Monbeen accomplished with much success. This combina- oxide on Alkalies,” Dissertation, Karlsruhe, 1910. 16-B. A. S. F..D. R. P. 265,295 (1912); 1,075,085 (1913). tion may be of far-reaching importance in the develop17-Greenwood, LOC.cit., Patents by deJahn, Haber and LeRossignoI, ment of direct synthetic ammonia manufacture. I n Bosch and Mittasch. l&General Chemical Co. (deJabn), U. S. Patents 1,141,947 (1915); the United States, during the past year, t h e Solvay (19 15). Process Company and the General Chemical Company 1,143,366 19-B. A. S. F.,D. R. P. 259,870 (1911); 268,929 (1912) have together formed the “Atmospheric Nitrogen 2-B. A. S. F., D. R. P. 254.571 (1911): D. R. P 256.296 (1911): Corporation,” capitalized a t $j,ooo,ooo, for the pur- D. R. P . 275,156 (1911); U.S. Patent 1,188,530 (1916). A. S. F., D. R . P. 235,421 (1908); D. R. P. 259,996 (1911). pose Of nitrogen fixation in this country’ D. R.21-B. p, 270,192 (1912); U. s, Patent 1,202,995 (1916). I n Great Britain a corporation has been formed in 22-G. A Goodenough, “Properties of Steam and Ammonia” (3. which the Brunner-Mond Company (ammonia-soda Wiley & Sons,Inc., 1915). 23-Perman, J . Chem. Soc., 83 (1903), 1169; M. J. Eichhorn, in process) is financially interested, and which has S5,000,- “Ice and Refrigeration,” Chicago (August 1918). 24-“National Defense Act,” approved June 3, 1916, Public Docu-000 available capital t o design, build, and develop ment, War Department, Bulletin 16, June 22, 1916. the direct synthetic ammonia process. 25-”Statement of Action Taken and Contemplated Looking t o t h e The situation with regard t o private operation of Fixation of Nitrogen,” by Division T, Ordnance Office, War Department, a plant in this country does not apply t o the govern- Aug. 21, 1917, THIS JOURNAL, 9 (1917), 829. 26-General Chemical Co. (deJahn), Brit. Patents 120,546 (1918); ment plant a t Sheffield, Alabama, built as a war 124,76&1-2 (1918). emergency measure. There the United States owm 27-N. Caro, Chem. I n d . , 42 (1919), 877. a complete plant designed t o produce ammonia by a direct synthetic process. It had not reached an GASOLINE FROM NATURAL GAS. 111-HEATING VALUE, operative stage a t t h e close of the war, and conSPECIFIC GRAVITY, AND SPECIFIC HEAT siderable alterations will have t o be made before it By R. P. Anderson can be considered operative. The Nitrate Division UNITEDNA TURAI, GAS COMPANY, OIL CITY PENNSYLVANIA of the Ordnance Department, U. S. A., now has under Received May 12, 1920 way plans and redesigns for t h e modification of U. S. ’ T h e present paper of this series on natural-gas Nitrate Plant No. I t o bring t h a t plant t o successful gasoline problems is devoted t o a discussion of t h e operation. This should by all means be done as a following topics : military preparedness measure. It will be recalled ( I ) Relationship between heating value and numbyr t h a t Germany did not embark upon the World War of carbon atoms per molecule of hydrocarbon. until she had two independent nitrogen fixation pro( 2 ) Relationship between heating value and specific cesses-the cyanamide and the Haber-commercially gravity of gasoline. developed. This country should not, after the lessons (3) Effect of removing gasoline upon heating value of the war, permit itselffto be in a less favorable posiand specific gravity of natural gas. tion than was Germany six years ago. (4) Specific heat of natural gas a n d gasoline vapor. REFERENCES 1-F. Haher and R. LeRossignol, Ber., 40 (1907), 2144; 2. Elektrochem., 14 (1908), 181; Ibid., 19 (1913), 53; F. Haber, Chem.-Ztg., 34 (1910), 345; 2. Elektrochem., 16 (1910), 244; F. Haber, et a l , Ibid., 20 (1914), 597; Ibid., 2 1 (1915), 191. 2-Haber, D. R. P. 229,126 (1909); 238,450 (1909); Haber and LeRossignol, u. S. Patents 971,501 (1910); 999,025 (1911); 1,006,206 (1911); 1,202,995 (1916); Badische Anilin und Soda Fabrik, D. R. P. 235,421 (1908); 259,996 (1911). 3-B. A. S. F. (C. Boseh), U. S. Patent 1,102,716 (1914); Brit Patent 26,770 (1912); Fr. Patent 459,918 (1913); General Chemical Co. (deJahn), Brit. Patent 124,760 (1918). 4-H. C. Greenwood, “Industrial Gases,” (Ballisre, Tindall & Cox, 1920). 5-B. A. S. F., Brit. Patent 27,117 (1912); (C. Bosch) U. S. Patent 1,115,776 (1914); (C.Bosch) U. S. Patent 1,200,805 (1916). &General Chemical Co. (deJahn), Brit. Patent 120,546 (1918). 7-Vignon, Fr. Patent 389,671 (1908); B. A. S. F., D. R . P. 282,505 (1913); Brit. Patents 8,030 (1914); 9,271 (1914); U. S. Patent 1,196,101 (1916); D. R. P 289,106 (1914); General Chemical Co. (deJahn), Brit. Patent 120,546 (1918).
(I) RELATIONSHIP B E T W E E N HEATING VALUE AND NUMBER OF CARBON ATOMS P E R MOLECULE
If the assumption be made t h a t the relationship between t h e heating value of normal paraffin hydrocarbons, expressed in calories per gram-molecule, and the number of carbon atoms per molecule is a linear one, it becomes a simple matter to compute tables of heating values t h a t are valuable in the natural-gas gasoline industry. Such computations have been made for t h e heating values per lb., per gal., and per cu. f t . of vapor of the normal paraffin hydrocarbons, pentane to undecane, inclusive, and the results are incorporated in Table I. Thornsen’s figures for the heating value of methane, ethane, and propane form the basis of t h e table and have been included in it.
Sept., 1920
T H E J O C R N A L O F I N D U S T R I A L A N D ENGZNEERZNG C % E M I S T R Y
TABLEI-HEATING VALUESOF PARAFFIN HYDROCARBONS B C D E F G
A
Ca 1or i s per GramMol. 211,900 370,400 429,200
B. t. u. Specific Lbs. per B. t. u. B. t. u. Gravity Gal. a t per per per at 60° F. 6 Q 0 F. Gal. c u . Ft. hb 23,790 CHI.. . . . 1008.4 22,200 1763.6 CzHa. 21,620 2519 CaHs.. 21,320 3274 CaHio.. 0.6i61 5 : i i 4 11o:ioo 4029 21,130 CsHir 21,010 5.519 116,000 4784 0.6627 C6Hl4. 0.6877 20,920 5.727 119,800 5540 CiHia.. 0,7067 20,850 5.885 112,700 6295 CsHis.. 20,800 6.014 125,100 70.50 0.7222 CeHzo. 20,760 6.114 126,900 7805 0.7342 CioHiz. 6.185 128,200 8560 0.7427 20,730 CIlH24.. COLUMN B-Thomsen's figures for the hydrocarbons, methane, ethane, and propane (Landolt-Bijrnstein, "Physikalisch-chemische Tabellen," 1912, p. 909). COLTIMN C-The figures in Column C were obtained from the formula HYDROCARBON
........ ......... ........ ....... ......... ........ ........ ..... ........ ....... .......
.
... ...
...
..
...
.
... ...
.. ..
... ... ...
-
B. t. u. per lb. 20'375n 4-6832 (see Equation 4 of text) n 0.1438 COLUMN D-The specific gravities in Column D are the same as those given in Part I of this series (THIS JOURNAL, 12 (19201, 548), except that they
+
are here carried out t o four places. COLUMNE L b s . per gal. a t 60' F. in Column E were obtained by multiplying the specific gravities in Column D by 8.328. the weight of 1 gal. of water a t 60° F. COLUMN F-The values in Column F were obtained by multiplying the values in Column E by those in Column C COLUMN G-B. t. u. per cu f t . a t 60°F., 30 inches mercury, dry gas, as given in Column G, were computed from the formula H.V. = 755 2 n 253.2 (see Equation 6 of text).
+
According t o t h e assumption t h a t has been made, t h e relationship between calories per gram-molecule and carbon atoms per molecule for t h e normal paraffin hydrocarbons may be expressed by an equation of the form Cal. per gram-molecule = a n * b (1) where 12 represents t h e number of carbon atoms per molecule. Thornsen's values given in Table I were substituted in this equation with the proper values for n, a n d b y t h e method of least squares a and b were evaluated, giving t h e equation1 Cal. per gram-molecule = 158,650n 53,200 ( 2 ) Substitution of values of 12 from I t o 3 in this equation gives heating values within 0.03 per cent of the values given b y Thomsen. Since heating value expressed in B. t. u. per lb. may be obtained from calories per gram-molecule by dividing by t h e molecular weight of t h e hydrocarbon and multiplying by the factor 1.8, t h e relationship between B. t. u. per lb. and carbon atoms per molecule may be expressed b y t h e formula 158,650n 53.200 B. t. u. per lb. = 1.8 (3) 2,016 14.016n where 14.0161~, 2.016 represents the molecular weight of t h e hydrocarbon in terms of t h e number of carbon atoms. Equation 4 is a simplified form of Equation 3. 6832 B. t. u. per lb. = 20,375n (4) n 0.1438 The heating value of these hydrocarbons may be expressed on t h e basis of volume by the formula B. t. u. per cu. f t . a t 60' F., 30 inches mercury, dry =
+
+ +
+
+
)
+
1 Since this was written, it has been learned that LeBas (Proc. Chem. SOL.Lond., 23, 134; Chcm. News, 110, 26, 37) has suggested the equation
Cal. per gram-molecule = R (6n C 2) t o correlate the heating values of the various gaseous paraffin hydrocarbons. The ratio of 53,200 t o 158,650 is that of 1 t o 2.982, and the value of K which gives the correct value for methane gives a result only 0.17 per cent higher for undecane than that obtained from Equation 2.
853
+
where the expression 0.037065" 0.00533 represents t h e weight of I cu f t . of gas at 60°, 30 inches mercury, dry, in lbs. Since this expression is equivalent t o 0.037065 ( n 0.1438), Equation 5 may be reduced t o the following form: B. t. u. per cu. f t . a t 60°, 30 inches mercury, dry = 755.212 253.2 (6) This equation differs somewhat from t h e one employed in a previous article,l which is B. t. u. per cu. f t . a t 60' F. goinches mercury, dry = 754.7n 253.8. (7) Equation 7 was derived from a consideration of Thomsen's figures for methane and ethane only and is probably less nearly correct t h a n Equation 6 for values of n greater than 2. The difference between t h e values obtained b y substituting various values of n in t h e two formulas increases, of course, with increase in the value of %, b u t amounts t o less t h a n 0.1 per cent for undecane. It is evident t h a t the heating values given in Table I are for hydrocarbons in vapor form and t h e latent heat of vaporization must be subtracted from these values if heating values of the liquids are desired. Some idea of the accuracy of these computed values may be obtained by comparing the computed heating value of normal octane with t h a t determined by Richards and Jesse.2 The computed heating value of normal octane is 20,850 B. t. u. per lb., while t h a t obtained by Richards and Jesse amounts t o 20,560 B. t. u. per lb. Subtracting 130 B. t . u. for t h e latent heat of vaporizations from the computed value reduces i t t o 2 0 , 7 2 0 B. t. u. per lb., which is about 0.8 per cent higher t h a n the observed value.
+
+
+
(2)
R E L A T I O N S H I P B E T W E E N IFEATING V A L U E A N D
SPECIFIC GRAVITY O F GASOLINE
If t h e heating value of the various gasoline hydrocarbons, expressed in B. t. u. per lb., be plotted against specific gravity as shown in Fig. I , i t will be found t h a t t h e points lie very nearly on a straight line.4 By t h e method of least squares it was found t h a t the equation B. t. u. per lb. = 23,330 - 3500 G (8) represents t h e relationship between heating value and specific gravity very closely. If the values for specific gravity given in Column D of Table I be substituted for G in this equation, t h e heating values obtained agree within 0.03 per cent of those given in Table I. B. t. u. per gal. a t 60" F. may be obtained from B. t. u. per lb. by multiplying by 8.328 G, as shown i n Equation 9 . 1 2
*
THISJOURNAL, I 2 (1920), 548. J . Am. Chem. Soc., 32 (1910), 268, corrected in 86 (1914), 248. Longuinine, Compl. Fend., t a l (1895). 557.
4 Since the linear relationship holds closely for specific gravity and B. t. u per Ib., the formula which correlates specific gravity and carbon atoms per molecule must be similar t o the one which correlates B. t. u. per lb. and carbon atoms per molecule. The method of least squares gave the formula 11.82n 13.89 0 8433n 0.9907 G= 2.016 n 4-0.1438 14.016n where G represents the specific gravity of the hydrocarbon in liquid form. Substitution of different values of n between 5 and 11 gives values for t h e specific gravity of the various hydrocarbons that agree with the values given in Table I t o within 0,0005, except in the case of pentane where t h e difference is 0,001, and in the case of undecane where the difference is 0.0008.
-
+
--
-
,
854
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
B. t. u. per gal. a t 60" F. = (23,330- 3 j o o G)8.328 G (9) The curve represented by Equation 9 does not differ much from a straight line o ver t h e range involved (see Fig. I ) , and the linear equation B. t. u. per gal. at 60" F. = 14,200 I j3,joo G (IO) gives heating values of the various hydrocarbons within 0.04 per cent of those in Table I , except in the case of pentane where the difference is 0.1per cent.
+
Vol.
12,
No. 9
On t h e other hand, the specific gravity of a gasoline does not define exactly the average number of carbon atoms per molecule, t h e specific gravity of its vapor, the heating value of its vapor in B. t. u. per cu. f t . , or the volume of vapor required t o produce one gallon of gasoline, since t h e relationships between these characteristics and specific gravity are curvilinear. While t h e statements in this section apply strictly only t o mixtures of the normal paraffin hydrocarbons, they probably apply quite closely t o natural-gas gasoline and straight-run gasoline, since substances belonging t o other than t h e paraffin series would be present only in very smallamounts, and the presence of the isomeric forms of t h e various paraffin hydrocarbons would have but very little disturbing effect. (3) E F F E C T
OF
REMOVING
GASOLINE
UPON
VOLUME,
H E A T I K G V A L U E , A N D S P E C I F I C GRAVITY O F NATURAL
FIG.1
Equations 8 and I O are directly applicable t o gasoline, providing t h e assumption be made t h a t i t consists only of the normal paraffin hydrocarbons, pentane t o undecane, inclusive. I n other words, t h e formulas do not hold merely for the various individual hydrocarbons, but also for various mixtures of these hydrocarbons which might exist as gasoline. The composition of gasoline of a certain specific gravity might vary considerably as t o t h e number and relative proportions of t h e various constituents, but, under t h e assumption t h a t has been made, this would have no material effect upon t h e heating value of the gasoline expressed either in B. t. u. per lb., or in B. t. u. per gal.
GAS
The question as t o t h e effect of removing gasoline upon the heating value and specific gravity of natural gas is one of especial interest t o natural-gas companies and t o natural-gas consumers. At t h e present time, many users of natural gas feel t h a t their gas has been greatly deteriorated by t h e extraction of gasoline from i t . This opinion is not usually justified but is t h e natural result of ignorance as t o just what change has taken place. The consumer is familiar perhaps with some compression plant which is operating on gas whose gasoline content is high, and where t h e effect upon the gas volume and heating value is appreciable, and does not realize t h a t the gas produced by the gas company is usually of a different sort and contains but little gasoline. The reduction in volume due t o the removal of gasoline vapor from natural gas depends primarily upon the yield and specific gravity of the gasoline t h a t is produced ; the reduction in heating value primarily upon t h e heating value of the gas, and upon t h e yield and specific gravity of the gasoline removed; and t h e reduction in specific gravity primarily upon t h e specific gravity of the gas, and upon the yield and specific gravity of the gasoline removed. It is not a difficult matter t o determine experimentally what t h e change in volume, heating value, and specific gravity amounts t o in any given case, unless t h e change is extremely small, but it is frequently not convenient t o do so. It is also unnecessary, since this change can be computed with sufficient accuracy for all ordinary purposes if the necessary information is available. I n making the computation, t h e relationship between t h e specific gravity of the gasoline and ( a ) t h e specific gravity of its vapor, ( b ) the quantity of vapor required t o produce a gallon of gasoline, and (c) t h e heating value of this vapor in B. t. u. per cu. f t . must first be established. This can be done conveniently with the aid of a diagram such as is shown in Fig. 2 , where specific gravity of vapor is plotted against specific gravity of liquid for pentane, hexane, and heptane.l Let it be assumed t h a t the gasoline produced from the natural gas has a gravity of 90° BB. 1 Data from first article of this series, Table I, (1920), 548.
THISJOURNAL,
1%
T H E J O U R N A L O F I N D U S T R I A L A N D E N GI 137 E E R I N G C H E M I S T R Y
Sept., 1920
(=s= 0.6364 sp. gr.). Where t h e pentane-hexane line crosses t h e line OF go ' BB. gasoline, t h e specific gravity of t h e vapor is 2.627, and t h e gasoline composition 71.9 per cent C5HI2 and 28.1 per cent C6H14. Where t h e pentane-heptane line crosses the line of 90' BC. gasoline, t h e specific gravityof t h e vapor is 2.653, and t h e gasoline composition 83.3 per cent CsHlz and 1 6 . 7 per cent C7HI6. The average specific gravity of vapor is 2.64, which corresponds t o a composition of 77.6 per cent C6H12,14.1 per cent C6H14, and 8.3 per cent C7HI6. This appears t o be a reasonable composition for 90' BB. gasoline from natural gas except t h a t i t does not provide for t h e small percentages of butane,
855
90' B6. gasoline, and for mixtures of hexane, heptane, and octane in t h e case of 7 j ' and 80' BC. gasoline. This information is contained in Table 111. TABLE 111 Average C u . Ft. of Max. Vapor and Min. per Sp. Max. Percentage Gal. GRAV-Gr. Error Composition Correof ITY of of sponding t o Sp. Gr. Mix'Be. Vapor Sp. Gr. C4H10 CSH12 C6Hl4 ture 90 2 . 6 6 k 2 . 1 15.0 3 5 . 9 4 9 . 1 26.4 85 2 . 8 3 i 0 . 4 6 . 6 15.7 7 7 . 7 25.1 CsHi4 C ~ H CsHis ~ G 80 3 . 0 6 kO.2 87.5 8.0 4.5 23.8 75 3.39 f 0 . 8 36.6 40.4 23.0 22.1
Max. Error of Vol. Vapor i 0 . 2 C4H10, C I H ~ Z i O . l CsH14 mixtures 0.0
k0.1
CsHir,C7Hio CsH1q mixtures
The figures given in Table I V for specific gravity of vapor and cu. ft. of vapor per gal. represent t h e average of t h e values given in Tables I1 and 111. The heating values in the table have been computed from t h e specific gravities of t h e vapor by means of t h e formula E . t. u. per cu. f t . a t 60°, 30 inches mercury, dry = 1559.7 G9-t 144.6, this procedure being peimissible on account of t h e linear nature of the heating value-specific gravity relationship (G, = specific gravity of vapor). TABLEIV Probable Probable Heating Specific Gravity Value B. t. u. GRAVITY B%. of Vapor per Cu. Ft. 90 2.65 4278 85 2.84 4574 80 3.07 4933 75 3.38 5416
Probable Volume Vapor per Gal. Cu. Ft. 26.4 25.1 23.7 22.1
I t seems reasonable t o assume t h a t t h e values in Table IV apply quite closely (probably within I per cent) t o t h e ordinary natural-gas gasoline. With these values established t h e computation of the change in heating value or specific gravity of any natural gas may easily be carried out. %The relationship between heating value of gas before and after gasoline extraction is given by t h e for mula H. I T . untreated gas X I O O = H. Xr. treated gas x (100 - V) H. V. gasoline vapor X V (11) or H. V. treated gas = H. V. untreated gas X I O O - H. 1 7 . gasoline vapor X V I O 0 - l7 (12) where V represents t h e volume of gasoline vapor removed. Similarly, sp. gr. treated gas = Sp. gr. untreated gas X 100- s p . gr. gasoline vapor X V.
+
d64
d69
465
0.66
0.,67
0.,68
0.69
1
FIQ. 2
octane, nonane, etc. The maximum possible variation in t h e value for specific gravity of vapor from t h e value 2.64 is f o . 4 9 per cent if only pentane, hexane, and heptane be considered. Table I1 contains information obtained in this fashion for 7 j , 80, 8 j, and 90' BC. gasoline, both as t o specific gravity of vapor and as t o cu. ft. vapor per gal. TABLEI1
Average
Cu. Ft. Vanor p& Max. Percentage Gal. Error Composition Correof sponding t o Sp. Gr. Mixof SD.Gr. CsHia C6Hia CvHie ture 8.3 26.4 k0.5 7 7 . 6 14.1 25.1 kl.1 4 5 . 4 34.3 20.3 23.7 17.0 4 2 . 0 41.0 i1.2 22.1 9 . 6 86.5 3.9 kO.2
-_ and Min. nf -M-a y
Sp. GRAV- Gr. of ITY Bd. Vaoor 90 2 . 6 4 85 2 . 8 5 80 3 . 0 9 75 3 . 3 7
Max. Error of Vol. Vapor
100-
v
(13)
Figs. 3 and 4 show the percentage loss in heating value and specific gravity, respectively, as a result of t h e removal of different amounts of 90' Bk. gasoline from different grades of natural gas.l The effect of
1 I n preparing these curves, the possible effect of butane in 90' BB. gasoline upon the specific gravity and heating value of the vapor was f0.2 Ignored. This accounts for the difference between the values employed and r t O . 4 CsHin, C6Hi4 those given in Table IV. The effect of changing the specific gravity of the f 0 . 5 C~Hi~mlxtures vapor from 2.64 to 2.65 and the heating value of the vapor from 4263 t o iO.l 4279 is slight, modifying the per cent decrease in specific gravity from 11.53 per cent t o 11.67 per cent for a gasoline removal of 5 gal. per M cu. f t . Similar d a t a have been obtained for mixtures of gas of 1.50 specific gravity. Present indications are that 90' Be. butane,l pentane, and hexane in t h e case of 85' and from gasoline from natural gas contains appreciable amounts of butane even after distillation, and the probable presence of this constituent was taken into 1 Theoretical sp. gr. of butane a t 60° F. = 0.575, andcu. f t . vapor per account in preparing Table IV. gal. = 31.2. I
_
8 56
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
FIG. 3
increasing the Baume gravity of the gasoline produced from natural gas is t o decrease the change in heating value and specific gravity of the gas, the amount produced being kept constant. This effect is small, however. A very large percentage of t h e natural gas produced in this country contains less than 0.5 gal. gasoline per 1000 cu. f t . , and reference t o the figures will show t h a t the change in heating value and specific gravity is usually quite small. The obvious purpose of Fig. 3 is to make possible the determination, in a simple and fairly accurate manner, of the loss in heating value of natural gas as a result of extraction of gasoline by any of the methods in common use. It can be used in figuring t h e loss t o the consumer in the heating value of gas t h a t has been treated only when conditions are such t h a t t h e untreated gas could be transported from the point of production t o the point of consumption without gas& line condensation. Very frequently this unavoidable condensation of gasoline is large and of considerable importance in attempting t o determine t o what extent the extraction of gasoline as a commercial project affects the gas as it finally reaches the consumer. (4) SPECIPIC HEAT O F NATURAL GAS AND GASOLINE VAPOR
The specific heat of methane a t constant pressure is generally taken as equal t o 0.5929. So far as is known, the specific heat in vapor form of the other hydrocarbon constituents of natural gas has not been determined. On account of this lack of information, a relationship between the specific heat of a mixture of paraffin hydrocarbon gases and the number of carbon atoms per molecule has been worked out, based upon the assumption t h a t the molecular heat of a paraffin gas divided by t h e number of atoms in t h e molecule equals a constant. For methane the constant is 0.5929 X 16.032 __ - 1.90, 5 and for a mixture of paraffin gases, according to t h e assumption t h a t has been made, the relationship is 1292 2.0161~ 2.016 = 1.90 (14) H, x
+
3.n
+
+
2
Vol.
12,
No. g
FIQ. 4
or
+
+
0.2711 1.90 (3% 2 ) - 0.4067.n (1 5 ) 14.016.n 2.016 % 0.1438-where HP representi specific heat a t constant pressure, and n represents t h e number of carbon atoms per molecule of hydrocarbon. If i t is desired t o correlate specific heat and specific ~ be combined gravity of natural gas, Equation 1 6 may with Equation 1 5 t o eliminate n , thus obtaining Equation 17. Equations 16 and 1 7 are subject t o t h e assumption t h a t the natural gas contains only paraffin gases. Ggss - 0.0696 12 = 0.4842
+
HP =
H*
+
= 0.407
.103 + 0__ Ggas
(17)
Equation 1 7 may be modified so as t o give t h e volumetric specific heat of natural gas by multiplying it by 0.0765 Ggas, the weight in lbs. of one cu. f t . of the gas a t 60° F., 3 0 inches mercury, dry. I n this way Equation 18 is obtained. H P per cu. f t . = 0.031 Ggas 0.008 (18) Table V contains the specific heats by weight a n d by volume, a t constant pressure, of the important constituents of natural gas as c:omputed from E q u a tions 1 7 and 18.
+
TABLEV
VOI. sp. Heat at Constant Specific Sp. Heat Gravity at ConstanI t Pressure HYDROCARBON GAS (Air = 1) Pressure (Eng. Units) 0.593 ..... 0.025 M e t h a n e . . . . . . . . . . . . . . . . . . 0.554 0.506 0.040 Ethane.. . . . . . . . . . . . . . . . . . . 1.038 0.055 Propane 1.523 0.475 0.070 0.458 Butane.. . . . . . . . . . . . . . . . . . . 2.007 0.085 0.448 Pentane... ................ 2.491 0.100 0.442 H e x a n e . . . . ............... 2.975 0.437 0.115 Heptane . . . . . . . . . . . . . . . . . . 3.459 0.130 0.433 Octane.. 3.944 0.430 0.145 Nonane 4.428 0,428 0.160 Decane 4.912 0.175 0.426 Undecane 5.396
...................
.................. ................... ................... ..................
I n employing Equations 17 and 18, or t h e values given in Table V, t h e limiting assumptions must be kept constantly in mind. As stated before, t h e assumptions are: ( I ) t h a t the molecular heat of a paraffin gas divided by the number of atoms in t h e molecule equals a constant, and (2) t h a t t h e natural gas contains only paraffin gases. 1
Anderson, THISJOURNAL, 11 (1919), 299
Sept.,
1920
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
With regard t o t h e first assumption, i t appears quite probable t h a t t h e relationship mentioned ho¶ds quite accurately for ethane. If this be true, the equations t h a t have been worked out would apply t o natural gases where t h e average number of carbon atoms per molecule is less t h a n 2 , and most natural gases would be included in this class. The applicability of t h e formulas t o rich natural gases and gasoline vapor is problematical, a n d experimental proof of t h e accuracy of t h e basic assumption is needed. It will be noted t h a t t h e specific heat of t h e hydrocarbons t h a t constitute gasoline ranges from 0.426 t o 0.448. This is considerably less t h a n t h e value of 0 . 5 t h a t is generally employed for gasoline in liquid form. The assumption as t o t h e composition of t h e natural gas has been made purely for convenience. If analysis shows constituents other t h a n paraffin gases, it is a simple matter t o make the necessary corrections. SUMMARY
I-Formulas have been developed t o correlate the following characteristics of normal paraffin hydrocarbons : Calories per gram-molecule and number of carbon atoms per molecule (2) B. t. u. per lb. and number of carbon atoms per molecule (4) B. t. u. per cu. f t . and number of carbon atoms per molecule (6) B. t. u. per lb. and specific gravity in liquid form (8) B. t. u. per gal. and specific gravity in liquid form (IO) Specific gravity in liquid form and number of carbon atoms per molecule (Note) Specific heat and number of carbon atoms per molecule (IS) Specific heat and specific gravity in gaseous form (~7) Volumetric specific heat and specific gravity in gaseous form (18) 11-The relationships between specific gravity and B. t. u. per lb. and per gal. may be expressed quite accurately b y linear equations. The significance of this is t h a t t h e specific gravity of a mixture of normal paraffin hydrocarbons determines its heating value, expressed either in B. t. u. per lb. or B. t. u. per gal., regardless of what variation may take place in the number and proportions of constituents. This statement applies t o gasoline in so far as gasoline is a mixture of t h e normal paraffin hydrocarbons. 111-Probable values of t h e heating value and specific gravity of vapor, and volume of vapor per gallon have been computed for four different grades of gasoline. IV-Figures have been prepared showing the change in t h e heating value and specific gravity as a result of t h e extraction of different amounts of g o o BB. gasoline from different grades of natural gas. ALKALI FUSIONS, 11-THE FUSION OF SODIUM BENZENE ~ADISULFONATE WITH SODIUM HYDROXIDE FOR THE PRODUCTION O F RESORCINOL' By Max Phillips and H. D. Gibbs COLORI,ABORATORY, BUREAUOF CHEMISTRY,WASHINGTON, D. C.
I n a paper2 recently published from this laboratory, there ware given results of a series of experiments 1 Presented at the 59th Meeting of the Amerkan Chemical Society, St. Louis, Mo., April 12 to 16, 1920. 2 THIS JOURNAL., 12 (1920), 145.
857
ascertaining t h e proper conditions for obtaining t h e highest yield of carvacrol b y t h e fusion of sodium #-cymene sulfonate with sodium hydroxide. I n connection with these experiments an apparatus was devised especially suited t o t h e study of alkali fusion of aromatic sulfonic acids. Using this apparatus we have now completed a similar study of t h e production of resorcinol by t h e fusion of sodium benzene mdisulfonate with sodium hydroxide. Although this subject has received attention from a number of investigators, a survey of the literature shows quite conclusively t h a t , with possibly one exception, no systematic study of this problem has been made. There appears t o be no agreement among those who have contributed t o this subject as t o t h e proper method of conducting an alkali fusion of sodium benzerie m-disulfonate in order t o get t h e best yield of resorcinol. The recorded yields v a r y from about 2 0 t o IOO per cent. HISTORICAL R E V I E W
Among the earliest contributions on this subject those of Garrickl and V. MeyerZ may be mentioned. The former claimed t o have obtained an almost quantitative yield of resorcinol by the fusion of sodium benzene m-disulfonate with potassium hydroxide for V. Meyer in his paper gives no 2 t o 3 hrs. a t 230'. details as t o method or yield. Barth and Senhofer3 obtained a 90 t o 95 per cent yield of resorcinol b y fusing sodium benzene m-disulfonate with potassium hydroxide, b u t failed t o describe just how the fusion was conducted. T h e same authors in a second paper4 stated t h a t an almost theoretical yield of resorcinol was obtained by fusing the potassium salt of benzene m-disulfonic acid with potassium hydroxide, b u t again failed t o give any details as t o their method. Durands gave t h e following directions for making resorcinol: The sodium salt of benzene na-disulfonic acid is fused for from 24 t o 36 hrs. with five times its weight of sodium hydroxide (35 moles) in an iron pot provided with a mechanical stirring device and heated in an oil bath. The melt is dissolved in water, acidulated with sulfuric acid, and extracted with ether. No data are given as t o the yield or t h e temperature a t which t h e fusion is conducted. Binschedler and Buscho gave a description of t h e process of making resorcinol then commercially in use. Sixty kilos of sodium benzene m-disulfonate were added t o 1 5 0 kilos (17.6 moles) of molten sodium hydroxide, containing as little water as possible, and fused for from 8 t o g hrs. at 270'. An almost theoretical yield of resorcinol was claimed. Degener' was t h e first t o make a study of t h e various conditions affecting t h e yield of resorcinol, such as temperature and time of fusion, proportion of alkali t o be used, and t h e effect of substituting sodium Z. Chem.,
1869, 549. Ber., 7 (1874), 1308. 3 A n n , 174 (1874), 235. 4 Ber., 8 (1875), 1477. 6 Mon. Sci., 18 (18761, 696. 8 Ibid., 20 (1878), 1169. 7 J . grakt. Chem., [Z]20 (1879), 300. I
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