I S D C S T R I d L d S D ESGIYEE’RISG CHE-UISTRY
July 15, 1930
raw sugar products, on the one hand, aiid refinery products, on the other, are particularly marked, as might be expected. The disadvantages of the alkali disnlacement curves
325
Literature Cited (1) Spender and Toedt, Z T-er. dekt Zucker-Ind., 80, 1 (1930)
Observations of the Micro-Pyrometer and the GasFurnace Methods for Determination of Fusion Point of Coal Ash’ h f . C. K. Jones, Harold Farmer, J. Ed. Brewer, and Horace C. Porter Results are compared of ash-fusion-point determinaT h e Bureau of Mines has tions on ten samples of bituminous coal and three of recently carried out further i n v e s t i g a t i o n s by the anthracite, by four laboratories, two of which used the investigatioiis, under the Bureau of Mines laboramicro-pyrometer method and two the standard gasdirection of IT.-1.Selvig, for tories, a paper was published furnace method. The coals were selected on account the purpose of comparing reby F i e l d n e r , Selvig, and of their anomalous behavior in practice with respect wlts obtained b y t h e de Parker on “Coniparisons of to laboratory tests of ash-fusion point. the Stantlard Gas Furnace Graaf apparatus with those The Philadelphia Electric Company laboratory used 11i c r o - P y r o m e t e r and obtained on duplicate pora modified procedure in the micro-pyrometer method, Methods f o r Determining tions of the same samples by resulting from careful investigation, by parallel runs the I3ureau of Mines laborathe Fusibility of Coal Ash” in the standard gas furnace, of the effect of size and ( 2 ) . Later (October, 1927) tory using the standard A. S. thickness of the test sample. The data indicate fairly T . 11. gas-fL1rnac.e method. Fieldner, Selvig, and Sichols satisfactory agreement between results by this comThese c o m p a r i a o n s were presented a paper on “The pany’s method and those of the laboratories using the mar!e on nineteen coals by Clinkering of Coal Ash as standard gas furnace. The former were somewhat low, Related to Laboratory Fusifive laboratories besides that by comparison, on the high-fusing ashes and high on bility Deterniinations” beof the Bureau of hlines. The the low-fusing ashes. They conformed somewhat more report of the results of this infore the American Society of closely to the results of practice. vestigation is now in press ( 3 ) . Mechanical Engineers, Fuels Buckwheat anthracites that clinkered in household Division, a t its meeting a t The purpose of the present furnaces using blowers were indicated by the standard paper is to present comparaSt. Louis, hfo. I n these gas-furnace test to have highly refractory ash, while papers the authors discussed tive results obtained on the the micro-pyrometer test indicated in some instances limitations of the m i c r o ash of thirteen coal samples a moderate clinkering tendency. pyrometer method and made by different laboratories, two The data do not show anything as to possible agreecomparisons of the results obof which used the standard A. S. T. h1. gas-furnace ment between different laboratories using stipulated tained by that method, asthen operated, with results by the m e t h o d and three others procedure with the micro-pyrometer method. standard American Society the electrically heated platifor Testing Materials metKod, using the gas-fired furnace. num strip or so-called “iiiicro-pyrometer” method. Two For several years previous to this time the United Gas Im- of these laboratories, although using the electrical platinum provement Company’s laboratory, in Philadelphia, had been strip method, modified the procedure of the de Graaf method using a method for this determination involving electric as recommended for same by Eimer and Amend (1). This heating of a platinum strip, on which a minute sample of modification had to do with the careful preparation, shaping, the ash was placed in a tray of thin platinum foil, determin- and placing of the test portion of ash on the heated strip. A large coal company operating mines in the Miller “B” ing the temperature by an optical pyrometer of special conseam, Cambria County, Pa., submitted ten samples of coal struction. Soon after this, G. A. de Graaf, in the laboratories of the obtained from that region to the laboratory of Horace C. Public Service Gas and Electric Company of Fern Jersey, Porter, Philadelphia, Pa., for test of fusion point of ash, a t Newark, developed an electrically heated apparatus for stating that they %-ereobtaining tests on these coals (samples this purpose, using a platinum strip also, but applying certain taken from the same 60-mesh lot in each case) also from the mechanical means of control of the heating rate, using a radia- laboratory of Einier and Amend, Yew York, by the de Graaf tion pyrometer directed on a small area of the strip to measure method. By agreement with the coal company, Porter subits temperature, and placing a thin layer of the finely pow- mitted samples of the ash of these coals, also, to Harold Fardered ash directly on the platinum strip. This apparatus is mer, chief chemist, Philadelphia Electric Company, and to now being sold by the laboratory supply house of Eimer and XI. C. K. Jones, chief chemist, Consolidated Gas, Electric Amend in New York under the name of the “De Graaf Electric Light, and Power Company of Baltimore, both of whom used the electrical platinum strip method, and samples of the 60Apparatus for Fusing Point of Coal Ash.” mesh coal to the Chemical Service Laboratories, Inc., PhilaReceived March 28, 1930. Presented before the Division of Gas delphia (J. Ed. Brewer, chief chemist), who used the standard and Fuel Chemistry at the 79th Meeting of the American Chemical gas furnace. Society, Atlanta, Ga., April 7 to 11, 1930.
I
S 1922, as a result of
ASdLYTICAL EDITIOS
326 Coal S a m p l e s S t u d i e d
These coals have from 16 to 20 per cent volatile matter, 5.1 to 6.7 per cent ash, and 1.1 to 2.2 per cent sulfur. Two of them (Nos. 2651 and 2657) had come from aregion in Cambria County known to produce coal of rather low ash-fusion test, according to the Bureau of Mines (4) averaging 2110" to 2370" F. (1154" t o 1299' C.). The other samples were of coal from the same seam as the two just mentioned but froin different mines, known commonly as coals of fairly high ashfusion test, averaging, according to the Bureau of Mines (4) close to 2670" F. (1466" C.), for coals of their range of sulfur and ash content. 811 these coals were reported by the company submitting them to have given more or less trouble with clinkering on mechanical stokers under forced-draft conditions. The above-mentioned lower-fusion-test coals gave a eomemhat more easily running clinker, but all clinkered to some extent, which seemed hardly in strict accord with the laboratory fusion tests. I n addition to these ten samples, three samples of anthracite buckwheat (two of KO. 1 buckwheat and one of N o . 3 buckwheat or barley) were used in this comparison by the different laboratories. These were chosen for the reason that clinkering had been observed in the use of these coals in household furnaces, apparently in contradiction to the indications of ashfusion tests in the laboratory. Cooperating Laboratories
The five laboratories cooperating and their designations as used in the acconipanying tables and figure \$-ere as folloTvs: (A) Horace C. Porter, 1833 Chestnut St., Philadelphia, Pa. (B) The Chemical Service Laboratories, Inc., J. E d . Brewer. chief chemist, Eighteenth and Cherry Sts., Philadelphia, Pa. (C) The Philadelphia Electric Company, Harold Farmer, chief chemist, 2301 Market St., Philadelphia, Pa. (D) Consolidated Gas, Electric Light, and Power Company, X. C. K. Jones, chief chemist, Baltimore, Md. (E) Laboratory of Seaboard By-product Coke Co., Kearny, h7,J., H . J . Meredith, chief chemist (conperating with Eimer and Amend, Chemical Apparatus Department, Kew Uork). 1 I e t h o d s Used
LABORATORY -1 used the st'andard A. S.T. Sf. gas furnace method and a Leeds and Northrup optical pyrometer, Calibrated by melting points of pure gold and nickel. LABORATORY B used the standard A. S. T. 31. gas furnace method and a plat'inum thermocouple, omitting, however, to prepare the powdered ash by preliminary heating in oxygen, and omitting the use of dextrine in molding the cones. LABORATORY c, the Philadelphia Electric Company, used a iiiodified de Graaf method which is described here in detail by Mr. Farmer, owing to its important bearing on the deductions to be drawn from this investigation: The Philadelphia Electric Company had concluded from previous investigations, made by them of the de Graaf apparatus in a series of tests checking i t against results b y the gas-furnace method, that the softening temperature of the coal ash \\-as greatly influenced by the size and thickness of the test sample placed upon the heated platinum strip. Final selection of the definite size of ash pellet was goyerned by these parallel tests. The procedure is as follows : (1) Preparation of Ash. The ash obtained from the regular ash determination is pulverized t o a n impalpable powder in a n agate mortar. Just sufficient water is added, drop by drop, to give a pasty consistency. ( 2 ) Pellet Mold. A special brass mold has been devised consisting of two small brass plates, inch (0.8 mm.) in thickness, which lie side by side and slide together on guide rods. Along the two edges of these plates, meeting each other, are cut six semi-circular openings, opposite each other, forming, when
Vol. 2, s o . 3
the plates are together, circular openings inch (1.6 mm.) in diameter and l / 8 2 inch (0.8 mm.) deep. (3) Preparation of Pellets. The pasty ash mixture is rubbed over the mold so as completely to fill the circular openings and smoothed off with a spatula. After drying in the air or on a warm plate, the two sections of the mold are drawn carefully apart and the small pellets of ash may be pushed out. (4) Placing of the Pellets f o r Test. Two pellets of each ash are placed crosswise of the platinum strip, l / 4 inch (6.4 mm.) apart, within the area previously determined as the field of the radiation pyrometer. It is important not to have any wavy, wrinkled, or roughened condition in the platinum foil where the pellets are placed. (5) Atmosphere. The cylindrical chamber containing the heated platinum strip and test pellets is filled, previous to the test, with a n atmosphere of carbon dioxide. (6) End Point. The end point is selective. Proper selection can, however, be acquired by the operator so that he may check himself within 20' F.(11' C.), and so t h a t different operators, after practice with each other, can check within 50' F. (28' '2.). It is a difficult point to describe. A settling down of the cylindrical pellet can be noted at its base, where i t is in contact with the heated platinum, and the fusion point is taken as that point where such settling down forces out a noticeable amount of softened material at the base beyond the diameter of the upper portion. (7) Rate o j Heating. The platinum strip is heated at a uniform rate of 750' F. (417' C.) per minute up to 1900" F. (1035" C.) and then a t a rate of 200" F. (111' C.) per minute. (8) Calibration. The temperature readings of the pyrometer were calibrated by the melting point of copper and for the higher temperatures by powdered Seger cone material of known softening points. (9) Initial Softenirzg Point. The selection of a point at which the ash first shows indications of softening is difficult and would vary widely between different laboratories. The Philadelphia Electric Laboratory chooses the point a t which any softened parts, or fluxes, are shown, leaving the vertical wall of the shaped specimen near its contact with the heated platinum. This is naturally a lower point than the initial softening temperature obtained in the gas furnace, since the latter relies upon a softening or distorting of the entire cone by the early formed fluxes. (10) Aside from the points of procedure above mentioned, and particularly the selection of end point, the test is carried out as prescribed by the manufacturers of the de Graaf apparatus.
LABORATORY D followed the de Graaf procedure recominended by Eimer and Amend ( I ) . The initial softening point is taken as the temperature at which there can be noticed a thin, white border spreading around the specimen when viewed through the magnifier. The fusion point is taken as the temperature a t which the last rough and somewhat darker spots disappear and the specimen appears fused completely. A test sample, the size of a pin head, of the powdered ash is placed upon the platinum strip and flattened with a spatula, reducing the specimen to a thickness of l j e 4 inch (0.4 mm.) or less. In the present investigation, Mr. Jones, of this laboratory, ran one set of determinations also with test portions somewhat larger and in thicker layer. The atmosphere used was air.
LABORATORY E was chosen by Eimer and Amend as one which had been investigating the de Graaf apparatus and had developed a modified procedure designed to give results approaching closely those of the standard gas furnace method. H. J. Meredith, chief chemist of this laboratory, has contributed the following detailed description of his procedure used in obtaining the results herein reported: A small mold is used for preparing minute cones of the powdered ash. This mold consists of a strip of monel metal, l / a inch (0.8 mm.) in thickness, in which has been bored a cone-shaped hole inch (0.8 mm.) in diameter a t its base and tapering to a point. The ash is ground to 200 mesh in a n agate mortar moistened with a drop of water and placed into the mold with a spatula. The surplus ash is removed by rubbing the surface of the plate with the finger and the base of the cone made slightly convex and smooth by pressing it with the head of a pin. The cone is moved by pushing i t out with a pin point from the reverse side. The cover is placed over the platinum strip and the apparatus purged out with carbon dioxide. The switch is turned on and the platinum strip heated until there is evidence of molten ash a t the base of the cone. This will give a very bright spot. At this
I,VDUSTRIAL BAVD ESGINEERIiVG CHEMISTRY
July 15, 1930
point the contact on the rheostat is stopped, and if the molten ash forms a bright ring completely around the base of the cone, this is taken as the first end point. If the ring does not encircle the cone completely, the rheostat contact is connected again until i t does. The heat is continued until the cone sags abruptly into the molten ash a t the base, and this temperature is recorded as the second end point. Table I-Analysis
%
%
2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2643 2647
6.71 5 69 5.39 5.30 5.48 5.89 5.09 5,go 6.06 6.14 13.90 1 2 . 70
2.17 0.88 1.32 0.92 1.17 1.42 1.63 1.15 1.52 1.34 0 59 0.78
2670
1 4 7.5
0 51
a n d Description of Coals Used
Semi-bituminous, Cambria Co., P a . , Nanty-Glo region Semi-bituminous, Cambria Co., Pa., Miller B seam Semi-bituminous, Cambria Co., Pa., Miller B seam Semi-bituminous, Cambria Co.. Pa.. Miller B seam Semi-bituminous, Cambria Co., Pa.; Miller B seam Semi-bituminous, Cambria Co., Pa., Miller B seam Semi-bituminous, Cambria Co., P a . , Nanty-Glo region Semi-bituminous, Cambria Co., Pa., Miller B seam Semi-bituminous, Cambria Co., Pa., Miller B seam Semi-bituminous, Cambria Co., Pa., Miller B seam Anthracite No. 1 Buck (clinkers under forced draft) Anthracite S o . 1 Buck (clinkers in SDencer marazine heater) Anthracite S o . 3 Buck (less clinkering than with S o . 2661,j)
Discussion
Table I1 and Figure 1 show the comparative results obtained by the five-laboratories, It is evident that the one laboratory (D), using the stipulated procedure of the de Graaf method without modification, obtained very much lower fusion points, in all but two cases, than were obtained by either the Philadelphia Electric Company's modified method or by the laboratories using the standard gas furnace. The two exceptions were ?;os. 2631 and 2657, the samples of lowerfusing coal previously mentioned, which checked well in all but one of the laboratories (E). There n-as poor agreement between the stipulated de Graaf procedure (laboratory D) and the other laboratories on the higher-fusing ashes, the maximum variation being 570' F. (317" (2.1, and the mean variation (of the eight samples) being -368" F. (-205" Figure 1-Variances C.), as referred to the average of laboratories A. B.and C. Hotvever. when this laboratory modified the de Graaf procedure to the extent of using a somewhat larger and thicker test portion, this variation was considerably reduced. The modified de Graaf method used by the Philadelphia Table 11-Comuarative
327
Electric Company gave results which checked fairly well the average results of the two laboratories using the gas-furnace method. On the lower-fusing samples the results by the Philadelphia Electric method were somewhat high as coinpared with the gas-furnace results. The initial softening points by the Philadelphia Electric method were generally 200" to 300" F. (111" to 167' C.) lower than those obtained by the gas-furnace method, except that on the two coals of low-fusing point the reverse was true and the initial softening points were about 300" F. (167" C.) higher than by the gasfurnace method. The modified de Graaf procedure used by the Seaboard By-Product Coke Company was very similar to that of the Philadelphia Electric Company, except that minute cones of regular shape and size mere used in place of cylindrical pellets. These cones were smaller than the pellets, being only inch (1.6 inch (0.8 mm.) at the base as compared with mm.) diameter of the pellets. The weight of ash in the cone was therefore considerably less than in the pellet. I n spite of this difference in quantity of ash taken, it appears that the results obtained by the two laboratories independently were in fair agreement. It is indicated, therefore, that b y development of a uniform standard procedure somen-hat in line with that used by the
by Micro-Pyrometer M e t h o d a t Different Temperatures and by Different Laboratories
Philadelphia Electric Company or the Seaboard Company, and with care in operation, particularly in selection of the end point, such a modified de Graaf method may, in the hands of suitably trained operators, give results checking witli
Results of Ash-Fusion-Point Determinations by Direrent Laboratories
1
1-2850
0 51
1616 1621 1427
1566
+2950 2600
2826
1552
2.17 0.88
2300 2930
2305
1263
2650
1260 1610
1454
2720
0.92 1.17 1.42 1.63 1.15 1.52 1.34
2840 2760 2560 2330 2840 2640 2710
1560 1516 1404 1277 1560 1393 1488
+2860 2s25
1493 1566 1662 1477 1307 1566 1399 1566
15 90 12.70 14 75
0 59 0 78
2651 2652 2653 '2654 2655 2656 2657
6.71 569
2658
2659 2660 a
5.59 5.30 5.48 5.89 5.09 5.90 6.06 6.14
1.32
2690 2385
+2850 1
2560 2850
=
c.
2500 2770 2740
1538 1521 1304
2412 251.5 2310
1322 1380 1266
2420 2683
"C 1327 1474
2480
1360
2400 +2800
1316 1538
2315 2423
1269 1329
2560 2615
1416
2323
1273
2700 27-50 2640
1482 1510 1449 1343 1499 1454 1488
2420 2427 2330 2370 2258 238.5 2370
1327 1330 1277 1299 1237 1307 1299
1404 1435 1371 1471 1349 1454 1343
F.
+a940
264: 2647 2670
2580
2450 2730 2650 2710
This series was run with a somewhat larger and thicker test portion than series I.
O F .
2500
2680 2460 2650 2450 2470 2470 2450
13,X
1354 1343
OF.
"(.
2520 2705
1382 1485
2705
1433 1302
2733 2650
2590 2687
1424
1421 14i5
328
SA1-.4LYTICAL EDITIOS
reasonable closeness those obtained by the gas-furnace method. It cannot be expected that any such empirical method of test can be made to give closely checking results in the hands of different operators, but there appears to be a possibility that the modified test as above described may be found useful as a rapid control method. The electrical method has a number of advantages: (11 its convenience, using only a small space and requiring only the small sample of ash obtained from the analytical determination; ( 2 ) its great saving of time as compared with the gas-furnace method; and (3) the greater possibility of attaining uniformity in heating rate and uniformity of atmosphere surrounding the samples. It is realized that objections to the electrical method may be raised, as, for example, the following questions : (1) Whether a truly representative sample of the total ash
of the coal can be obtained in so small a test portion as is used in this test. (2) Whether there is a sufficiently close contact of the ash pellet with the heated platinum foil to get uniformity in this respect in successive tests. (3) Whether the field, about 3 ' ~inch (9 5 mm.) diameter, on the platinum foil affecting the radiation pyrometer reading is always uniform in temperature throughout its area,
The Philadelphia Electric Company, however, as a result
of careful and extensive tests conducted for this purpose. particularly b y successive check determinations by the same and b y different operators, is satisfied that, for the purpose of routine Rork in testing the quality of coal deliveries, the method is satisfactory and yields results closely approximating those that are obtained by the standard gas furnace. The work of developing this modified de Graaf procedure has but recently been completed in the laboratories of t h e Philadelphia Electric Company. It is proposed now to check u p the possibilities of the method by having comparative determinations made in other laboratories with which the Philadelphia Electric Company is associated. The ability of different laboratories to check each other on the same samples b y using this modified procedure will thus be determined. The Philadelphia Electric Company has found the modified de Graaf method, as herein described, to be a great time saver in checking the ash-fusing quality of coal deliveries, so that when an indication is obtained thus of a coal's testing belomthe normal requirement, then a check determination, by the standard A. S. T. M. method using the gas furnace, is run, and complaint to the coal shipper based thereon. The rapid method is found to save thus a great deal of time and expense as compared with the more elaborate standard gas-furnace method. Mr. Jones, of Laboratory D, tested on two samples the effect of running in a partial carbon dioxide and carbon monoxide atmosphere (by keeping on the platinum strip during the test a piece of charcoal), getting, under these conditions, somewhat lower figures than in air. Samples 2654 and 2655 gave thus, respectively, 2540" and 2445" F. (1393" and 1341' C.) as compared with 2680" and 2460" F. (1449" and 1349" C.) in air. The results on the three samples of anthracite coal indicate that the de Graaf method, even as modified by the procedure of the Philadelphia Electric Company, tends to give results 150' to 200" F. (83" to 111" C.) lower than the standard gas furnace. The question may be raised whether the results by the modified de Graaf method do not more closely parallel the clinkering results obtained in practical use of the coals. This cannot be definitely anmered without more exhaustive and closely controlled tests of the clinkering properties of
Vol. 2,
KO.
3
these coals, although it' may be said that the consumer's report of the clinkering in practical use was not in line with the laboratory results obtained by the standard gas-furnace met hod, I n the opinion of two of the authors (Porter and Brewer), the procedure recommended by the manufacturers for use of the de Graaf apparatus, unless properly modified, is unsuited t o the obtaining of accurate and uniform results in the hands of different operators. The variation between the results obtained by different operators using the de Graaf procedure without modification may reach as high a figure as 500" F. (278" C.) depending very much upon the size and thickness of t'he test portion used and the personal equat'ion in choosing the end point. A11 the authors agree, however, that there are possibilities of working out a modified procedure somewhat along the lines of those used by the Philadelphia Electric Company arid the Seaboard By-Product Coke Company so that much more uniform results can be obtained and that the method, so inodified, may be found useful for rapid control work. Literature Cited (1) Eimer and .Imend, Circ. 402 (1928). ( 2 ) Fieldner, Selvig, and Parker, J . I n d . Eag. Chem., 14, 693 clR221). (3) R. I. 3003,Bureau of Mines. ( 4 ) Selvig and Fieidner, Bur. Mines, Bull. 209 (1919).
Subsequent Additions of Acid in Carius Combustions' David D. Hartley INDIANA UKIVERSITY,
BLOOMIKGTOS, IND.
sulfur determinations b17 the Carius method, IacidSor3IAKISG other combustions in a sealed tube, the amount of added is sometimes insufficient for complete decomposition. Also in some instances i t may be undesirable to add a sufficiently large amount of acid initially. The further addition of acid is by most methods a troublesome procedure, but the following one has been found quick, neat, and convenient. A glass tube of 5 t o 8 mm. bore is sealed a t one end and cut to a length of 5 to 10 cin., depending on the quantity of acid to be added. The open end is then partly closed, leaving an opening of 2 to 3 mm. diameter. This tube is placed upright in any convenient holder and the desired quantity of acid placed in it by means of a small-tipped pipet or a glass tube which has been drawn down to a capillary. The Carius tube, which has been sealed in such a way as to leave a capillary for subsequent opening and resealing, is opened and stood in a vertical position. The small tube containing the acid is inverted-the acid docs not flow out in this position-and brought down just over the open end of the capillary. The Carius tube is cooled with a damp towel and the acid flows in without leakage. The cooling is usually unnecessary owing to capillary action and absorption of the gases by the acid. Received M a y 12, 1930.
