Hydrogenation and Petrography d
U
of Subbituminous Coals and Lignites R E L A T I V E L Y abundant L. L. HIRST, H. H. STORCH, per cent oil distilling from 200" reserve of low-rank coals C. H , FISHER, AND G . C. SPRUNK to 330" C. (392" to 626" F,). exists i n the western About 25 per cent of this oil is Crntral Experiment Station, United States (I), and the coals phenolic; the yields of tar acids U. S. Bureau of Mines, Pittsburgh, Penna. of this region vary widely in on the moisture- and ash-free coal rank from lignites to bituminous. are given in Table I. The tar A preliminary hydrogenation survey of these coals in 1.2acids boiling to 235" C. (455" F.) contain about 50 per cent xylenols, 40 per cent cresols, and 10 per cent phenol. liter bombs has been published ( 3 ) . The present paper is concerned with the hydrogenation assay of three subbituWhen the tar acids boiling above 235" C. are recycled, a reminous coals and two lignites in the Bureau of Mines excovery of a n additional 25 per cent of these as low-boiling acids perimental plant (6,6, 9, IO, 11). The assay procedure conmay be obtained. The neutral oil contains 40 to 70 per cent sists in pumping a mixture of about equal parts of powdered aromatics, and about 10 per cent olefins; the remainder is coal and a heavy oil along with hydrogen under 200 to 300 saturates (a mixture of paraffins and naphthenes). Perhaps atmospheres pressure into a vertical alloy-steel tube. 3 inches the most significant data to be correlated with rank are those given for the total yield of aromatic oil in the fifteenth i. d. and 8 feet long, heated to 430-450" C. (806-842" F.). The contact time and temperature are varied until a maximum column of Table I. With the exception of the Mary Lee coal, yield of oil, carried out of the converter by the stream of hythere is a steady decrease in yield of aromatics with increasing drogen, is obtained. A heavy oil in which the ash of the coal, oxygen content (tenth column, Table I). The maximum total the unreacted coal, and the catalyst particles are suspended aromatic yield is obtained with the high-volatile A coal. If the decrease for the Mary Lee coal is not due to the difficulties is discharged through a standpipe about 6 feet above the experienced in locating the optimum conditions for this coal bottom of the converter. This heavy-oil slurry is centrifuged, ( 5 ) , this maximum is sigpificant and indicates the effect of and the resulting oil is mixed with another charge of coal and increasing coalification in reducing the reactivity of coal. catalyst. Thus the assay consists essentially in determination The organic residue predicted from petrographic analyses of the optimum conditions for the maximum oil yield con(Table 11)in the fourth column of Table I is reasonably close sistent with complete regeneration of the tar-oil vehicle used to that obtained (column 5) in the experimental plant. This in making a paste with the original coal. Table I contains a summary of the assay results. For prediction is based upon the assumptions that none of the fusain, and only 60 per cent of the opaque attritus, will hycomparison the results of the assay work on four bituminous coals are included. The bituminous coal results were given drogenate to produce liquid products (4).
A
,
TABLE I. EXPERIWESTAL PL.4NT 1
2
3
4
5
6
7
54 of D r y Coal
Or; Or; HgO, 70 ganic ganic of Coal residue residue as preobCoal Ranka Bed and State hIined dicted tained 4.2 9.8 Mary Lee, Ala. 9.0 H. V. A, bit. 1.6 7.8 4.0 Pittsburgh, Pa. ' . A, bit. H. 1 4.9 7.8 5.4 N o . 6, Ill. H. V. B bit. 0.5 1.1 9.6 McKay, Wash. H. V. C: bit. 4.2 24.1 5.6 Puritan, Colo. Subbit. B 8.2 25.1 6.7 Rosebud, Mont. Subbit. B 2.6 23.2 3.1 Monarch, Wyo. Subbit. B 7.6 34.9 9.7 ' . Dak. Beulah. h Lignite 6.6 4.7 39.5 Velva, N. Dak. Lignite = H. V. = high-volatile; bit. bituminous.
-
~
.4sh 10.2 5.7 7.1 4.1 5.4 10.1 5.1 12.3 7.4
8
ASSAYS
9
Oil Yields, 7cof: Moistureand ashCoal free Dry as coal coal mined 60 54 52 65 64 70.5 70.5 65 60 66 68.5 59 63 60 45 60 55 40 64 49 68.5 50 54.5 31 52 32 49
in greater detail elsewhere (6). The ninth column of Table I shows that (except for the Mary Lee coal) there is a steady decrease in the yield of oil per ton of coal as mined with decreasing rank of coal. The seventh column of Table I shows that this decrease in oil yield with rank is much more gradual when it is calculated on a dry, ash-free basis. The oil obtained in these assays contains about 20 per cent gasoline and 70
10
Oxygen 5.0 6.8
10.0
12.5 16.4 16.2 16.9 19.4 21.2
11
12
13
14
15
70Moisture- and Ash-Free Coal
T a r acids Distill- Distill- distillHy- ing to ing ing to Total drogen 235 23;-330 230 arqmatused C. C. C. ics 3.5 2.3 32.8 8.5 3.9 40.9 7.6 3.5 2.8 9.0 7.0 1.3 4.4 37.1 8.5 27.7 8.1 3.2 7.6 4.9 2.6 6.0 9.7 6.2 28.2 6.9 7.5 6.9 26.4 1.8 7.1 25.4 2.8 8.5 7.8 6.1 5.3 23.5 1.3 8.0 6.1 22.1 1.8 7.0 8.0
16
Gas 27 21 17 22 J 26 ,5 19 25 28 23
The eleventh column of Table I shows that there is little, if any, trend with rank of coal observable in the percentage of hydrogen used, based upon the moisture- and ash-free coal. However, the hydrogen used per ton of oil produced (column 11 divided by column 7 , Table I) increases from about 12 per cent for bituminous coals to about 15 per cent for lignites. This increase is much smaller than one might have predicted 1372
INDUSTRIAL AND ENGINEERING CIIEMISTRY
OCTOBEI\, 1940
upon considering the oxygen contents (column 10, Table I) of the coals. This somewhat surprising result apparently is due to removal of most of the oxygen as carbon dioxide rather than as water, when the oxygen content exceeds about 10 per cent.
Geology, Petrography, and Chemical Analysis A sample of Colorado subbituminous B coal was taken from the Puritan mine of the National Fuel Company in Weld County, Colo. This mine operates in an unnamed bed, of the Laramie formation, that ranges from 6 to 10 feet in thickness. It is one of tho largest mines in northeastern Colorado and produces a subhituniinous coal typical of that area. This area is part of the Denver coal region, which consists of a continuous strip of coal-hearing rocks beginning a few miles north of Colorado Springs and extending north for about 140 miles. The width of this coal region averages about 40 miles.
AND CHEMICAL ANALYSES TABLE 11. PETROGRAPHIC
Puritan, Monarch, Rosebud. Beulah. Velvs. Colo. Wyo. Mont. N. Dak. N. Dak. Aa-Rereiued Raaia. ..... ~,VA ,” 25.1 34.9 39.5 23.2 Moisture 24.1 26.0 28.5 26.0 31.2 Yolstile matter 29.1 38.8 31.0 30.0 41.7 Fired carbon 42.7 8.0 4.5 3.9 7.6 Ash 4.1 % of Moisture-Free Coal 4.6 4.3 4.5 5.1 Hydrogen 4.7 66.6 69.0 64.2 71.7 Carbon 72.1 1 .0 1.0 0.9 1.5 Nitrogen 1.5 15.5 10.0 14.6 16.9 19.8 OISW” Sulfur 0.4 0.6 0.7 1.5 0.6 Ash 5.8 5.1 10.1 12.2 1.5 % oi Moisture- and Ash-Free Coal 5.0 5.3 5.2 4.9 4.9 Hydrogen 78.7 73.0 72.0 75.6 Carbon 76.6 1.6 1.5 1.1 1.0 1 .n Nitrogen 19.4 21.4 16.8 16.2 OWgWJ 16.4 0.4 0.7 0.8 1.7 0.7 Ciulfvr Petrogrsphio Analysis. %* 31 63 51 64 61 Anthrsrylon 32 33 20 27 Trsneluoent. sttritus 55 13 14 9 opnaue sttr3tua 10 4 4 1 3 2 3 xvanin *Baaed 0” mio~o~oupic estimation of arc_ in, nlimerous thin Beetiom msde from a vertical column of cod out from a working iaoe of the oosl sesm.
Cod Constituents
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Campbell ( 1 ) of the United States Geological Survey has estimated the Colorado coal reserves at more than 300 billion tons. The coal fields lie on both flanks of the Rocky Mountains; in general, the coal near the flanks is of bituminous character, and that at some distance has retained its subbituminous character. The petrographic and chemical analyses of the Puritan mine coal are given in Table 11,along with those for the other subbituminous coals and lignites. Since the halogens are active hydrogenation catalysts ( 1I ) , the halogen content of the coals of Table 11 was determined. It was found to be 0.01 per cent or less for all of them. Another subbituminous coal sample was obtained from the Monarch KO. 45 mine a t Kleenhurn, Sheridan County, Wyo. The Monarch is one of the important beds of the Sheridan coal field, which is situa.ted east
