INDUSTRIAL AND ENGINEERING CHEMISTRY
644
It will be further noted that the data applied to these calculations are on fractions which are distillates and of fairly narrow boiling range. To determine the application to wider boiling oils a few blends have been prepared of light and healy fractions from the same crude and the constants calculated. These values are shown in Table V. Apparently the relations
Vol. 20, Xo. 6
continue to hold for blended oils from components of widely different viscosities. The viscosity-gravity constant is certainly not above criticism. It has been found, however, to be a useful index in the authors' laboratory and is communicated in the hope that it may prove similarly useful to others
Fusion of Coal, Coke, and Motor Fuel by Sodium Peroxide' George E. Mabee ROCHESTER GAS A L D ELECTRIC CORPORATION, ROCHESTER, N. Y.
A
RECENT valuable article on the fusion qf coal and coke by Fieldner and Selvig,2 of the Bureau of Mines, tabulates results which afford a comparison of three methods for determining sulfur in fuel. Since the sodium peroxide method is thought worthy of a place among the A. S. T. M. Standards, it seemed timely to the writer to call attention to the manner of conducting the fusion, before the method is finally written up. I n the article mentioned the method as it is now used is set forth, and the results are said to be sufficiently close to those obtained by the Eschka method to justify its use as an alternate standard. The purpose of this article is t o show another way by which coal and coke may be fused with equal facility and more completely in the case of coke. It probably has been noticed that coke does not fuse completely by the present method, although the amount of unburned material has not been found to exceed 2 per cent. The combustion seems to be arrested by loss of heat, especially with slow-burning material like coke. Several years ago the writer, using the Parr peroxide calorimeter while working on bituminous coal, found from 0.4 to 0.6 per cent of unburned material. The cartridge used in the calorimeter is essentially the same as that used for sulfur determinations, but is immersed in water, which increases the rate of radiation and thus makes it difficult to complete the combustion. This criticism does not apply to bomb calorimeters, in which the fuel is burned in a cup and is not in contact with the walls of the bomb. Regardless of the means used to ignite the charge, the cartridge should not be immersed in water during combustion. The 15 grams of sodium peroxide used can supply all the oxygen needed for the combustion of 0.5 gram of coal or coke, and the addition of chlorate, because of its ability to furnish more oxygen, constitutes a daring attempt to outrun the effect of radiation, which nevertheless succeeds with those fuels having sufficient volatile matter. The use of benzoic acid with anthracite and coke is simply a means of supplying the volatile matter that they lack. Following this conclusion, it was decided to use means to prevent radiation losses through which it was hoped to dispense with the use of potassium chlorate and benzoic acid. This was done by placing the cartridges in a muffle furnace a t about 800" C. The screw couplings and washers were, of course, left off, and in order to have sufficient clearance in the muffle the milled knob was removed from cartridge cover. This produced a complete fusion with a wide variety of fuels, as will be shown later, and demonstrated that potassium chlorate and benzoic acid are not necessary. The cartridge became evenly heated all over before the 1 9
Received September 9, 1927. IXD.ENG.CHEM.,1 9 , 7 2 9 (1927).
charge ignited, instead of having one hot spot as formerly, which favors a better combustion. The cartridges were given 2 minutes in the furnace, although less might have been sufficient. The ignition was found to occur in from 20 t o 30 seconds. The muffle can be protected from any possible spattering of peroxide by placing one thickness of asbestos paper on its floor and allowing it to extend a little way up on the sides. The accompanying table gives a partial list of the fuels tested. They are samples received from the Bureau of Mines, on which the writer had previously made tests, the results of which were incorporated in the article cited.2 They represent widely separated sections of our country and are as widely separated in their nature. These tests have been carried through to completion-i. e., sulfur content-to show that concordant results are possible. SAMPLE A B C
D
E F
G H I
JK
.I
hl h-
0 P
SOURCE
A P P R3XIMATE ~ A X A L Y S ~ SDRY , BASIS Volatile Ash ---Sulfur-matter
Pennsylvania Washington Illinois Appalachian field West Virginia Kansas Appalachian field Appalachian field Unknown Interior Province Illinois Mississippi lignite Illinois Interior Province Anthracite Metallurgical coke
%
%
%
%
24 45 32 37 25 35 22 26 45 39 43 27 39 37
11.0 7.8 14.8 12.6 11.2 8.8 5.9 14.5 13.2 8.4 12.1 44.0 10.6 16.0 16.9 16.3
2.58 0.56 1.11 3.87 1.31 4.36 1.99 4.46 6.84 3.26 8.23 17.42 5.54 10.47 0.87 0.59
2.65 0.53 1.19 3.68 1.42 4.28 1.90 4.52 6.84 3.26 8.35 17.57 5.34 10.42 0.88 0.62
% 3.73 2.01
8.24 17.56 5.38 0.61
The proposed method requires no more time than the one now in use and is somewhat simpler since there is less weighing and couplings are not needed. Aside from this the possible danger from chlorate, as pointed out in the Bureau of Mines article, is eliminated. The difference in sulfur results, however, may not be apparent because of the small amount of sulfur in coke. Fusion of Gasoline, Motor Benzene, or Highly Volatile Mixtures Difficult to Handle in Calorimetric Bomb (For purpose of determining sulfur)
A 50-ml. nickel crucible is set on a standard in a 600-ml. beaker, about 3 mm. off the bottom of the beaker and surrounded by water to half its height. The charge consists of 15 to 18 grams of sodium peroxide and 1 ml. of the fuel to be tested, which are mixed in the crucible and a thin layer of peroxide spread over it. The crucible cover is replaced by a copper canopy of the same diameter as the beaker and similar to a watch glass with the convex side up,
IYDUSTRIAL -4ND ElVGI.VEERI-VG CHEMISTRY
June, 1928
which is supported 2.5 cm. above beaker by three legs which rest on the rim. IGNITION OF CHARGE-sodium peroxide combines with certain organic compounds with sufficient energy to inflame them, among which are the primary alcohols. This property is useful because the fusion cannot be started from without as with coal or coke. Onehalf milliliter of alcohol is run in from a pipet after the canopy is set in place, and spontaneous ignition occurs in 10 seconds when using absolute methanol. The ignition can be retarded by mixing benzene (sulfur-free) with the alcohol, or denatured alcohol may be used. The writer has found 10 seconds ample time for safety, and prefers methanol without any admixture because it burns without depositing carbon, whereas benzene and sometimes ethyl alcohol will deposit carbon, which may be due to insufficient time for complete mixing with the peroxide.
645
An energetic combustion is preferred and, in fact, is necessary to insure completeness; nevertheless it must be under control. Too little peroxide increases the violence of combustion while too much may retard combustion to the point of incompleteness. A little experience will simplify this adjustment. The manner of ignition is important. The method in use in this laboratory is to heat an iron rod to incandescence and plunge it into the crucible through a hole in the cover. The action of the peroxide on the iron rod introduces a large amount of iron into the fusion, which when dissolved requires considerable time to filter, and a possible source of error lies in the danger of some sodium sulfate being carried down with the precipitated iron. Ignition by alcohol obviates this danger.
Automatic Apparatus for the Determination of Small Concentrations of Sulfur Dioxide in Air' Moyer D. Thomas and Robert J. Cross DEPARTMENT OF . 4 G R I C r L T U R A L RESEARCH, AMERICAN SMELTING
K T H E study of smelter-
ASD
RSFININGC O M P A N Y , S A L T L A K E CITY, U T A H
An automatic apparatus has been constructed to to 20 liters per minute. This analyze continuously air containing sulfur dioxide in observation was also made ins m o k e p r o b l e m s it is concentration from 0.1 to 60 p. p. m. The apparatus de pen d e n t 1y by Houston essential to have an anameasures out the absorbing liquid, draws a definite volLetcher, of Stanford Univerlytical method which will ume of air sample through it, and discharges the assity. The method described estimate rapidly and continupirated solution into a bottle ready for titration. in this paper makes use of this ously small amounts of sulfur The method has been checked with satisfactory redioxide in air. Although the fact by drawing the air sample sults by comparison with the Selby method and also continuously, and the analyconcentration of this gas in by analyzing known mixtures of sulfur dioxide and air. t h e n e i g h b o r h o o d of a sis is made automatic to the Data are submitted to indicate the stability of the modern smelting plant probpoint a t which the solution iodine solution and its efficiency in absorbing sulfur ably never exceeds 10 p. p. m. is titrated. This method has dioxide. by volume, it is desirable for been extensively used with A modification of the automatic apparatus suitable investigational work that the entire satisfaction in fumigafor field determinations of sulfure dioxide in air is a n a l y t i c a l method should tion studies and in the field. cover-a range of concentration described. Apparatus from 0.1 to a t least 30 p. p. m. The method of Marston and Wells, as described by the A diagram of the automatic apparatus is given in Figure 1. Selby Smelter Smoke Commission12has been the best one Operation is accomplished by means of eight cams, 8 , which available for this purpose. The process consists in drawing open and close a series of valves in proper sequence. The a sample of air into a partially exhausted 20-liter bottle camshaft is geared through a speed-reducing system directly containing a solution of iodine colored with starch, and ab- to a motor, which also operates a Nelson vacuum blast sorption is accomplished by shaking the bottle vigorously. and pressure pump. Poppet valves, D , F J , are used in the The method has the drawback that it is laborious and inter- liquid system and consist simply of beveled glass rods ground mittent. Objections urged against it by Weierbach3 on the t o seat against the sloping walls above the constriction in ground that the iodine attacks the rubber stoppers and tubing glass tubes. Mercury-seal valves, N , mounted on pivoted are without foundation if the rubber is first soaked in a 0.002 boards are employed on the air line, and are operated by N solution of iodine and subsequently in a more dilute solu- long levers from the cams which permit a tipping movement tion of about the concentration used in the analysis. Error of about 2 cm. in analysis due to oxidation of sulfur dioxide by oxygen from The reagent reservoir is a 20-liter bottle containing starch- , the air a t the surface of the glass seems to be inappreciable iodine solution of sufficient strength to absorb all the sulfur if the walls of aspirator are kept moist with iodine solution dioxide in the sample of air a t the maximum concentration while the sample is being drawn in. However, unless pre- of a given experiment. This bottle is closed a t the top and cautions are taken it is possible to introduce an error as provided with a discharge tube a t the bottom, which extends great as 5 per cent due to adiabatic cooling of the bottle on into a 500-cc. constant-level bottle, B. The latter comexhausting and adiabatic heating on admitting the air sample. municates through a g1a.s-wool filter, C, and two valves, It was observed by one of the writers in 1926 that complete D, with two inverted 100-cc. pipets, E ; and as these are absorption of sulfur dioxide could be attained by bubbling successively filled, the level of the liquid in the small reservoir the gas through a suitable absorber a t a rate as high as 10 bottle is maintained, because air is permitted to enter the large bottle when the lower end of its discharge tube is un1 R e c e i v e d February 6, 1928. covered. The pipet delivers its liquid to the absorber, G, 1 U 5'. But.. Mines, Bull. 98 (1915). * A m . J Botany, 13, 81 ( 1 9 2 6 ) . below, and when the gas sample has been drawn through
I
