October, 1931
INDUSTRIAL A N D ENGINEERING CHEMISTRY
the gain by the solution. The general procediire is similar to that followed in the integration of general equations for drying operations (1, 7 ) . However, rigorous solution of the problem is complicated by the fact that the unit of concentration c is based on a unit volume of solution rather than on a unit quantity of pure solvent. It seems desirable for ordinary purposes to make the simplifying assumption that the volunie of solution does not change during a dissolution process; that is, the volume of the solution is :ilways equal to that of the pure solvent. The errors involved will not exceed 5 per cent for many systems. With this assumption the weight balance is readily established exactly as in dryer calculations. ISOTHERMAL PnocEssEs-If a dissolution process is conducted without appreciable change in temperature, the integration of Equation 15 is considerably simplified. I n this case ct is constant and equal to the saturation concentration a t the temperature of operation. ADIABATICPnocEssEs-In a process conducted under adiabatic conditions, the temperature of the solution undergoes continual change as its concentration increases. Watson and Kowalke (8) have demonstrated a method whereby the relationship between temperature and concentration in such processes may be represented by dissolution charts, similar in principle t o this humidity chart. From the dissolution chart of a system, a second chart may be prepared relating cf to c. Such a chart for the system of sodium carbonate decahydrate and water is shown in Figure 9. The dissolution of this material is accompanied by absorp-
1151
tion of heat and reduction in temperature. For example, if dissolution is started with pure water a t a temperature of 20” C., the initial value of cf will be 22 grams per 100 cc. As dissolution proceeds and the temperature is reduced, ct diminishes, the solution finally becoming saturated with a concentration of 9.5 grams per 100 cc. By means of a chart, such as Figure 9, a graphical relationship between c and ct is established which permits integration of Equation 15 to apply to an adiabatic process. Acknowledgment
This investigation was conducted under the supervision of 0. 1,. Kowalke, chairman of the Department of Chemical Engineering, to whom acknowledgment is due for his helpful suggestions duping the completion of the work. The author is also indebted to 0. A. Hougen for his suggestions and critical review of the manuscript. Literature Cited (1) Badger and McCabe, “Elements of Chemical Engineering,” McGrawHill, 1931. ( 2 ) Gapon, Z . Elehrrochem., 34, 803-5 (1028). (3) Lewis, J. IND. ENG.CHEM.,8,825-32 (1916). (4) Lidell, “Handbook of Chemical Engineering,” p. 344, McGraw-Hill, 1922. ( 5 ) Murphree, IND. EKG.CHEM.,16, 148 (1923). (6) Thorman, Chem. A p p . , 16, 185-6,209-11 (1929). (7) Walker, Lewis, and McAdams, “Principles of Chemical Engineering.” McGraw-Hill, 1927. ( 8 ) Watson and Kowalke, I N D . END. CHEM.,22, 370 (1930).
Metallic Constituents of Crude William B. Shirey 110 WILLARDSI., BERLIN,N. H .
Samples of petroleums from different localities are a n a l y s i s of 99.94 per cent, N SPITE of the fact that analyzed. There is found to be a loose quantitative and of the H a r d s t o f t , ash, petroleum is rock oil and ratio between the vanadium and nickel content in the giving a summation analysis closely associated with petroleum ashes. In so far as other mineral constituof 96.99 per cent. Ramsay the mineral world through ents of petroleum are concerned, little or no regularity (5) has recorded a number of geologic time if not in the is found. Analyses do not reveal common occurrence analyses of nickel in petroprocess of its f o r m a t i o n , of metals in sufficient amounts to make petroleum ash l e u m oils, a s p h a l t s a n d very l i t t l e is k n o w n conof interest as a source of rarer metals. Ditches. his main obiect becerning i t s mineral or ing to ’uphold the Sabatierm e t a l i i c constituents. Thomas (8) called attention to the importance of the problem Senderens (7) theory of the formation of petroleum by hyin 1924: “The mineral content of petroleum has hitherto drogenation of simple substances, such as carbon monoxide been largely overlooked, to such a degree, in fact, that one or carbon dioxide, nickel acting as a catalyst. Hackford (4) rarely, if ever, finds a complete analysis of the ash quoted, cites the multiplicity of elements present in the ash from Mexialthough the percentage of the ash is invariably determined can oil as indicating that this oil was derived from marine in analyses of crude oils.” More recently, Gurwitsch (3) has plants, though he maintains that oils of different regions have stated: “The composition of the ash of petroleum oil is a different origins. This research was undertaken to study the quantitative matter of the greatest interest, as throwing light on the probable origin of petroleum-whether the ash content of crude relations between the various metallic constituents of peoils stands in relationship to their general composition is a troleum ash and to determine the possible presence of metals which may have had a catalytic influence on the genesis of the question not yet investigated.” Thomas (8) cites two quantitative analyses and a number oil. It was also thought possible that certain rare metals of qualitative analyses of Persian, Hardstoft, Pennsylvania, might be found present in valuable quantities. Samples of petroleum coke were obtained from different Mexican, Baku, Egyptian, Canadian, Ohio, Patagonian, Japanese, and Chidersynde petroleums. The only quantita- petroleum fields of the United States and these were contive analyses cited are of the Persian ash, giving a summation verted to ash for the analyses.
I
Received June 2, 1931. Project 30 of the American Petroleum Institute Research. Financial assistance in this work was received from a research fund of the American Petroleum Institute donated by John D. Rockefeller. This fund is being administered by the institute with the cooperation of the Central Petroleum Committee of the National Research Council. Dr. Gerald Wendt was director of the project 1 2
Histories of Coke Samples
CRUDE-The crude oil, which is piped (1) CALIFORNIA from the San Joaquin Valley fields to the Union Oil Company refinery, is not run to coke in this plant, and the coke received had not been through any plant treatment. A large
1152
IiVDUSTRIAL AND ENGINEERING CHEiMIXTRY
quantity of coke was available because of a fire which destroyed the oil stored in large concrete storage reservoirs (6). When the fire had burned out, the carbonaceous ash a t the bottom of one of these reservoirs was scraped out and dumped. There was a possibility here of contamination by dust and perhaps by disintegrated cement. Before the coke sample was selected, the top layers were carefully removed and this was, therefore, probably as clean a sample of petroleum coke as was obtainable for the purpose. On ignition, the coke yielded 1.61 per cent ash. (2) WYOMINGCRUDE-This sample consisted of coke and ash collected from the ash pits under the grates of certain of the stills in the Casper plant of the Standard Oil Company of Indiana which burned petroleum coke screenings from Wyoming crude oil. The material was neither a coke nor a fully burned ash, but contained about 9 per cent ash. The coke contained was material that had dropped through the grates unburned. This material was almost clean and its analysis representative, except that the iron content was probably high due to contamination from the grates and furnace. CRUDE-The sample, which was the (3) MIDCONTINENT first that was obtained for the problem, represented an ash collected from the ash box of a domestic furnace in which petroleum coke had been burned. The coke was the product of the crude-oil coking stills of the Standard Oil Company of Indiana a t Whiting, in which a typical mixture of Midcontinent crude is reduced to coke. While this ash served as a convenient starting point for the first analyses, i t is not reliable for a permament verdict on this oil since it was not clean-i. e., it contained charred wood, nails. etc., from other materials burned in the furnace. CRUDE-The petroleum coke was (4) TEXASPANHAXDLE produced from the distillation of Panhandle crude to a coke base in a crude-oil still of the Prudential Oil Corporation, of Baltimore, Md. The coke sample was very dry, porous, and free from foreign material. The ash content of the coke was 0.92 per cent. CRUDE-The coke was from an un(5) PENNSYLVANIA filtered and untreated fuel oil cut from a crude still of the Kendall Refining Company of Bradford, Pa. Therefore this ash was from condensed oil that had come over a stillhead, and such does not represent the residue left after distillation of an original crude to a coke base. The ash content of this coke was 0.91 per cent. This ash represents a sample entirely different from any other that was analyzed Its analysis is interesting to compare with the others since it gives Eome information concerning elements that are picked up from the stills in the refining process, as well as information concerning those that are lost from passage of the products over the stillhead. (6) KANSASCRUDE-This coke was produced by the Dubbs Process (2) (especially modified) in the stills of the Vickers Petroleum Company of Wichita, Kans. The coke was the residuum from the first chamber, which was operated under a pressure of 200 pounds. The raw oil was topped crude having a gravity of 26-27 Baum6. The crude oil came from the fields within fifteen miles of Potwin, Kans., at which place the re6nery is located. The coke, as received for analysis, was well saturated with oil and had a strong kerosene odor. The ash content of this sample was 2.06 per cent. The modified Dubbs Process reduces the coke to about onefifth the ordinary quantity. (7) OKLAEIOMA CRuDE-This sample represented the standard-run of coke from the Dubbs Process of the Texas Pacific Coal and Oil Company of Fort Worth, Tex. The cracking stock consisted of a mixture of about 50 per cent asphalt-base Robberson crude from Gamin County, Okla., which had a gravity of 21-23 Baum6, and 50 per cent Fox Pool crude from Carter County, Okla., which had a gravity
Vol. 23, No. 10
of 33 Baum4. The cracking stock, which is the topped crude from this mixture, had a gravity of 21 Baum6. The coke received for analysis was quite dry and brittle. Its ash content was 0.66 per cent. Preparation of Samples for Analysis
The cokes were crushed, ground, and sampled. They were then ashed by ignition in an electric furnace at a temperature of from 400" to 600" C., ample provision having been made for circulation of air. The ashes so obtained were completely ground in an agate mortar to pass a 100-mesh sieve. It is readily recognized that ash so prepared could have lost some of the more volatile metallic constituents that might have existed in the original crudes. Such loss also might have occurred during the coking process while the crudes were in the coking stills. The author's ambition to burn sufficient crude under such conditions as to insure complete condensation of all metallic constituents was thwarted by thermodynamic calculations and a realization of the stupendous difficulties involved, as well as by the expensive equipment required. Analysis of Samples
In most cases quantitative analyses were preceded by qualitative tests, covering both the common and the rare elements. Quantitative analyses were performed under strictly regulated conditions so as to leave little question as to their genuineness. Table I gives the analyses as obtained. The numbers heading the summation columns correspond to the numbers given in the preceding histories and represent the samples described. Samples
Table I-Analyses 1 2
% Si02 Combined oxides Fer01 MgO CaO Nap0
Kz0
PnOs MnO
%
38.79 4 0 . 3 1 22.38 51.48 (7.71)a (44.59) 1.81 1.19 8.68 3.45 9.51 2.58
...
...
of P e t r o l e u m Samples 3 4 5
%
%
%
6
7
%
%
31.68 1.55 0 . i 5 9.s9 3 1 . 8 0 10.32 9 7 . 5 2 19.55 (15.81) ( 7 . 7 4 ) (97.37) (14.69) 4.18 2.49 0.239 1 . 2 7 12.62 5.26 0.68 4.79 6 . 9 0 30.80 0.129 23.60 .. 1.03 ... 0.922
.
... ... ... ...
... ...
...
(0.06) 0 . 1 9 8 0'437 0 . 3 3 01213 6:Q38 1 : : VlOS Trace Trace (1.43) (0 438)(22.14) SOa (total) 1 . 4 4 10 80 4 2 . 1 1 0:875 36.41 ... SO; (water-sol.) ... (42.06) . (34.36) . . . 4.35 0 . 3 3 ~ 01433 1 . 5 2 None 0.571 5.89 Ni0 Liz0 0.144 0.163 . . . ... ... ... Chloride (water-sol.) . . . 4.64 0.10 Sum 100.99 i o i , ' i 4 98.'96 100.07 i00:io 9 7 . 2 4 a Percentage figures occurring within parentheses are not added in making up summation. 0:302 (5.07) 15.02
...
..
... ...
Discussion of Results
These analyses are offered as the most complete quantitative petroleum-ash analyses that have been accessibly recorded. Because of the high alkali content for most of the samples and the difficulties accompanying satisfactory determination of these, it was necessary to take especial precautions to prevent loss through heat treatment during such determinations. Since such precautions did not result in a good summation analysis for the Kansas Crude (6) there was some concern about this sample. It was thought that something might be interfering that had not been revealed qualitatively. Selenium and tellurium especially were looked for, but neither could be found. C. C. Nitchie of the New Jersey Zinc Company's research laboratories was asked to make a spectroscopic analysis, since he is especially equipped to do this type of work, and he gave the following report: ". . . .The ash shows no trace whatever of either selenium or tellurium. Judging as well as I can from the intensities of the principal lines, the composition appears to be as follows: Present in large amounts: sodium, silicon, iron, calcium, aluminum.
I,VD USTRI.4L A V D ENGINEERING CHEMISTRY
October, 1931
Somewhat less than above, but present in considerable quantities: vanadium, nickel, titanium, magnesium. Small amounts of: barium, strontium, manganese, lead, copper. Traces only of: chromium and silver.
. . . .I made careful search for all of the other elements which yield arc spectra, including all of the metals, as well as phosphorus, arsenic, selenium, and tellurium but could find none. . . . . This analysis was made on a large Gaertner quartz spectrograph covering on two plates, the wave length rangingofrom 2365 b. to 6700 b.,and the dispersion r%ngingfrom 2.3 A. per millimeter, a t the short-wave end, to 48 A. per millimeter in the red.” It was felt that this report did not justify spending more time with the sample, especially since the work for the problem was being brought to a close a t the time the above report was received. The analyses recorded for the Oklahoma Crude (7) do not represent an attempt a t a complete analysis, but are recorded as a further indication of a nickel to vanadium ratio, which will be discussed more fully later in this paper. The occurrence of vanadium in petroleum ash has been mentioned suggestively in discussing the origin of petroleum (8). Ramsay (5) has shown that nickel occurs in all petroleum crudes with which he has worked and believes that it occurs to some extent in all crudes. In the analyses just recorded the vanadium content runs relatively high in certain of the samples. Thomas (8) has called attention to the high vanadium and nickel content in the ash from certain mineral oils, and to the fact that high vanadium content has been observed for certain asphalts. More recently high vanadium content has been reported as existing in the ash from a Venezuela crude oil. In the latter case as high as 45 per cent vanadium was found (1). From the studies of this investigation it is shown that there is a very high percentage of vanadium and a relatively high percentage of nickel in the ash from the Oklahoma Crude (7), a medium content of each for the Texas Panhandle Crude (4), and finally, a relatively small content, especially of vanadium, for the Kansas Crude (6). While there is not sufficient data to make such a comparison, i t is expected that high content of both vanadium and nickel are generally associated with high asphalt-base crudes. If this is true, and if the quantities of these elements present are dependent on the quantity of asphalt in the crude, it would be expected that the relative magnitude of asphalt content of the crudes, the ashes of which were analyzed, could be roughly expressed as follows: Oklahoma Crude > California Crude >Texas Panhandle Crude >Kansas Crude > Midcontinent Crude and Wyoming Crude. In support of this comparison, Table I1 is given, relating vanadium and nickel to asphalt crudes.
1153
ash samples. This was done by careful tests for radioactivity by means of sensitized photographic plates. Copper, lead, zinc, gold, or silver have not been found in the ash of petroleum in any quantity. Attention is called to the variance of the phosphorus content of the samples investigated in this study as compared with those recorded by Thomas (8). For the two quantitative analyses he records 5.53 per cent and 2.34 per cent, calculated as P205. The ash from the Wyoming Crude (2), which gave a heavier qualitative test for phosphorus (using a one-gram sample) than any of the samples that were worked with, gave only 0.06 per cent Pz05. Reference to the figures for analysis of ash from the Pennsylvanian Crude (j),which had been over the stillhead, will give some evidence of losses occurring during the coking process. Such vaporization losses might have been either partial or complete, but for most of the elements concerned in this work, complete loss does not seem feasible. Small losses have probably occurred for the alkali and alkaline-earth metals. On the other hand, probably much of the iron has, in many cases, been picked up from the stills during the coking processes. In conclusion it is pointed out that there is a loose quantitative ratio between the vanadium and nickel content as found in the petroleum ashes that were analyzed; that while nickel apparently occurs to some extent in the ash from all crudes, vanadium appears to associate itself more strictly with the asphaltic crudes and may appear in only the most minute traces, or probably not a t all, in some of the more strictly paraffin-base crudes; and finally, that in so far as other mineral constituents of petroleum are concerned, little or no regularity has been found. Iron cannot be considered very seriously from any standpoint, since there is too much possibility here for contamination, both from pipe lines and from the stills. The presence of these mineral constituents in the oils may be due (1) to emulsified sub-surface waters, (2) to a true solution of the minerals in the oil, or (3) to formation of chemical compounds between the metals and the organic constituents of the oil. Because of the presence of vanadium and nickel, which have not been reported in related waters, the first hypothesis is not probable. The more complicated organic compounds which constitute asphalt may serve either to dissolve or react with the metallic compounds, and no decision on that point is possible on the basis of present results. The analyses did not reveal common occurrence of metals in sufficient amounts to make petroleum ash of interest as a source of rarer metals. Acknowledgment
%
%
5.03 None reported 22.14 0.44 1.43 Trace Trace
2.70 None reported 5.89 0 57 1.52 0.52 0 33
Expression of appreciation is due to C. C. Nitchie, who kindly cooperated by making a spectrograph analysis; to the officials of the oil companies whose names are mentioned in the histories of the ash samples given in this paper, and in addition to these, the Schaffer Oil and Refining Company of Cushing, Okla.; the Shell Company of Martinez, Calif.; the Texahoma Oil and Refining Company of Wichita Falls, Tex.; the Maryland Refining Company of Ponca City, Okla.; and the Pure Oil Company of Ardmore, Okla., for their cooperation in furnishing coke and ash samples for these studies.
It is a well-known fact that vanadium, uranium, calcium, barium, zinc, copper, lead, and molybdenum often occur together, or rather, some combination of these elements practically always occurs with vanadium. It is interesting to note that uranium (which usually occurs in greater quantity than the other elements mentioned as associated with vanadium) and other radioactive elements have been shown not to occur to a large extent in any of twelve different petroleum-
(1) Broz, Arh hem f a r m , 4, 86-90 (90-1 in German) (1930). (2) Chatfield, Nall Pelroleurn News, 19, 31, 83-87 (1927). (3) Gurwitsch, “Scientific Principles of Petroleum Technology,” translated and revised by Moore, pp. 149,218,220 Chapman and Hall, 1927. (4) Hackford, J . I n s f Petroleum Tech., 8 , 193-213 (1922). (5) Ramsay, I b i d , 10, 87-91 (1924) (6) Reed, A m Petrolium I n s l . Bull , 8 , No. 6 (1927). (7) Sabatier and Senderens, Cornpl r e n d , 134, 1185-1188 (1902 ) (8) Thomas, J . I n s f Petroleum Tech.. 10, 216 (1925).
Table 11-Vanadium a n d Nickel in Asphalt Clrudes SOURCE OF CRUDE BASE VlOl NiO Persian ( 8 ) Hardstoft ( 8 ) Oklahoma, 7 Kansas, 6 Texas Panhandle, 4 Midcontinent. 3 Wyoming 2
1.17y0 asphaltum Purely paraffin Asphalt
References t o L i t e r a t u r e
