Feb., 1912
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 .
efloresce on the surface, and can be removed readily b y simply shaking. Practically all the potassium salts can be obtained b y lixiviation of the dried plant or of its ash. Neither Nereocystis nor Macrocystis of the Pacific littoral contain a s much iodine as many other seaweeds and rockweeds. Nevertheless, the amounts present are notable and contrary t o popular belief; the southern kelp contains more than does the northern. According t o Turrentine’s analyses Nereocystis contains about 0.16 per cent. and Macrocystis about twice as much. Besides iodine, other useful products can be obtained from these kelp, of which, however, space will not permit a discussion here. It is not possible as yet to give a n accurate estimate of the amount of potassium chloride which the Pacific kelp groves can yield annually. With all conditions a t their best the maximum possible yield might b.e in the neighborhood of 8 million tons, worth a t present prices about $300,000,000. No such yield is probable, however, a t least in the near future. Taking every cons deration, and leaning strongly t o conservatism i t may be said t h a t i t ought t o be perfectly practicable t o obtain a n annual yield of at least a million tons of potassium chloride, worth a t present prices upwards of $30,000,000. The iodine obtainable a t the same time should go far toward paying the expenses of harvesting the kelp and extracting the potash. I t has been assumed in some quarters t h a t because the kelp can be made to yield about three times the present total potash importations from Germany the latter will be stopped or greatly diminished. This is very much t o be doubted. Existing business engagements will ensure continued importation for some years t o come. I t is possible, and greatly to be desired, t h a t potash from American kelp will reduce the price of potash salts. But the vast bulk of the potash salts goes into the South Atlantic States because these states a t present are the great fertilizer consumers. Inevitably the Trans Mississippi States must soon use fertilizers and in fact the movement has already begun. A very large increase in the consumption of fertilizers, and therefore of potash, may be anticipated within the next few years, enough probably t o take up the American production in sight and the importation t o be obtained from Germany as well. The great importance of the kelps lies not in the probability of their excluding German potash, but ( I ) if properly managed, in preventing a monopoly and regulating prices; (2) in making possible a greatly extended use of fertilizers, and thereby perhaps even stimulating importations; and (3) in times of stress, giving the country a resource and preventing the agricultural interests from being a t the mercy of an outside power. F. K. C A M E R O N .
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SURFACE COMBUSTION.
In view of the wide-spread publicity given to the lecture of Professor IT. A. Bone, of Leeds, before the American Gas Institute at St. Louis and the Chemsits’ Club in New York, October, and especially in view of the general acceptance b y gas engineers and chemists in general of his process as a new discovery in combustion, it seems highly desirable t o present a brief review of this art. Professor Bone’s demonstrations were all concerned with the burning of explosive gaseous mixtures continuously b y method which (quoting) “consists essentially in injecting, through a suitable orifice at a speed greater than the velocity of back firing, an explosive mixture of gas (or vapor) and air in their combining proportions into a bed of incandescent, granular refractory material, which is disposed around or in proximity to the body to be heated.”
This method of burning explosive gaseous mixtures was used b y C. E. Lucke, in 1900, or about eleven years ago. I t was made the subject of a long series of experiments, the results of which were published in a paper entitled “The Heat Engine Problem,’’ presented to the American Society of Mechanical Engineers, December, I 90 I , and forming part of his Doctor’s Dissertation, from which the following is quoted: “The desirability of being able to burn a n explosive mixture continuously and non-explosively under commercial rather than laboratory conditions having been long obvious, a series of experiments was undertaken a t Columbia University with this end in view. Many experiments were made and various results obtained, but as a full account would take too much space and avail little, only a few characteristic experiments will be noted as leading up to the result. Consider a mass of explosive mixture passing through a non-conducting tube with a uniform velocity, v . Then, if inflammation be started at some point, the surface of combustion may remain a t rest or move with or against the current. Denote the rate of propagation by r. Then, when v is greater than r the surface of combustion will move with the current, and if the tube has an end, the flame will ‘blow OB’ and combustion cease; if v = r the surface of combustion will remain a t rest, other influences being inoperative; if v is less than Y , the surface of combustion will move back toward the source, or ‘back flash.”’ “ I n a practicable system of burning an explosive mixture continuously, we may state the following as desiderata and later see how they can be secured. I. ‘Back flashing’ must be prevented. 11. ‘Blow off’ must be prevented. 111. Combustion surface must be localized. IV. It must remain localized for wide ranges of feed or velocity of fl\~wof the mixture. V. The localization must be unaffected by changes of temperature. VI. Large or small quantities must be burned without affecting the above, and the transition from very small quantities to very large, or vice versa, however sudden, should be easy. The first requirement might be accomplished in three ways: ( a ) By using a long tube of some conducting material and so small in diameter as to prevent the passage of the flamecap under any circumstances. ( b ) By using wire gauze*screens.
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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 J T I S T R Y .
( c ) By causing the mixture t o flow a t some point with a velocity always greater than the rate of propagation. The first ( a ) is impracticable, as it permits of only small quantities being burned; the second ( b ) will not work when the wire gauze gets hot; this leaves ( c ) which is practicable.” “Hence we must p u t down as the first requirement in our desired method of combustion the following: At some point before the combustion surface is reached the velocity oj jeed must be such that v is greater than r . Requirement I1 might be accomplished in three ways: ( a ) By so reducing the velocity after passing the high speed point that we have at some surface v = r . ( b ) By suddenly increasing the temperature of the mixture so as t o increase the rate of propagation while ‘i’remains constant; or (c) By reducing z’,by spreading the current, and increasing r by heating. All of these ways are practicable; but, as a reduction of velocity alone or a sufficient heating alone would not produce the desired results so well as both operating together, there was introduced as the second requirement in our desired method, the following: After passing the fioint where v is greater than r , the velocity of the mixture should be so reduced and its temperature increased as t o make v 1 = r’.” “Many ways of bringing about the above were tried, b u t only one seemed preeminently good by reason of its simplicity and effectiveness, for i t fulfils most perfectly the requirements proposed for our desired method; this is, to fill a cone with fragments of refractory material such as pottery, broken crucibles, bits of magnesite, or any other rock t h a t will stand the high temperature without fusing. I n cones of 60 degrees, inch and with a ‘/,-inch orifice, I have ound pieces of about diameter to answer well. These separate pieces of solid matter interpose many reflecting surfaces without materially hindering the advance of the mixture, and cause it tosspread in the way desired, keeping the surface of combustion spherical and preventing diffusion. A variation of velocity causes the spherical surface of combustion to vary only in diameter, and the limits of feed are determined only by the size of the cone.” “ A cone of given altitude will give the greatest range of variation of diameter of cross section when its angle is 180 degrees. This is a plane surface which, with the orifice and broken rock should appear as in Fig. (Fig. 49, page 58, ‘TheHeat Engine Problem’). Here the surface of combustion is approximately a semi-sphere. Trial shows t h a t this arrangement
Feb., 1912
is further augmented by reason o j the increase of the late o j firopa. gation caused by the passage o j the mixture between the hot fragments. Hence both principles operate simultaneously toward the desired end.” “ W e have thus arrived a t a method of continuously burning explosive mixtures of all sorts, whether in the chemical proportion or not.” “When a chemical proportion is maintained in the mixture, all the combustion takes place on the combustion surface, giving absolutely neutral products of combustion, but when a n excess of gas is present within certain limits, all gas t h a t can find oxygen burns explosively between the solids, while the excess acts merely as a neutral diluent to be burned when it meets a n oxygen atmosphere later on. By properly placing the oxygen atmosphere to burn the excess gas, we can get the hot products either reducing or oxidizing-reducing after leaving the explosive combustion surface and before meeting the excess of oxygen in the atmosphere, oxidizing after t h a t meeting. ”
This quotation is reproduced, together with other similar matter b y Hutton in his book “ T h e Gas Engine, ” 1903, pages 486-493. I t cannot, therefore, be said that the scientific and technical world has not had opportunity enough t o become acquainted nu
2
.
U
Fig 3.
Fig. 1.
Fig.2
works perfectly, and the limits of feed are determined only by the size of the pile of rock surrounding the opening. A cone of 360 degrees, or no cone at all suggest the surrounding of the nozzle by broken rock without any enclosing walls Fig 2 (Fig. 5 0 , page 58, ‘The Heat Engine Problem’). This arrangement also works remarkably well. The surface of combustion is here approximately a sphere giving the greatest possible increase in area of the surface of combustion for the distance traveled from the nozzle. ” “ N o t only is the greatest possible range of action by velocity reduction thus obtained, enabling the greatest possible amount of mixture to be burned in a given volume, b u t this amount
with this work, done some eleven years ago and in print for ten years, especially as many journals quoted portions of the A. S.M. E. paper, mentioned above, as well as quotations from another paper b y the same author, presented to the A. S. M. E., May, 1902, on the application of the same process to the burning of oils. Not only does it appear from the above t h a t Lucke practiced this process for both gases and oils prior t o 1901,but two patents were issued t o him for the process. U. S. No. 7 55,376 and NO. 755,377, filed respectively June 7, 1901, and July 30, 1901, both issuing March 22, 1904, contain illustrations and descriptions of apparatus substantially the same as used by Bone, but t h e claims cover the method broadly and are not confined to the apparatus shown. To make clear the comparison, consider Figs.’3 and 4, which are reproductions of the patent illustrations,
Feb., 1912
T H E J O U R I V A L OF I N D U S T R I A L . AND El\iGIA’EERING
with Fig. 5 , reproduced from the Americart Gas Light Journal, illustrating Bone’s Apparatus (Dec. 4, 1911). The following quotations of the patent claims will show t h e scope of these two patents in
P
CHEMIS~TRY.
79
stantially the same distance from the place where the spreading begins, thereby reducing the velocity of the mixture t o the rate of propagation of inflammation and preventing diffusion with other gas; and burning within the bed so much of the fuel a s herein forms with the supplied oxygen a n explosive gaseous mixture and burning a t or beyond the surface of the bed the remainder of the fuel, substantially as described. ”
I t would appear that these two claims of the method of burning explosive mixtures whether in chemically combining proportions or not, as used by Bone, are broadly covered and allowed. It is of interest in this connection to quote the U. S. Patent Office citations which were overcome in connection with the Lucke cases, and these are:. I , Verstraet, Jan. 1 2 , 1869; 2 , Smith, No. 170,198, Nov. 23, 1875; 3, Paquelin, No. 180,155, July 2 j , 1876; 4, Weeks, Oct. 1 2 , 1880; j, Hubbard, No. 260,983, July 11, 1882;6, Wainwright, Oct. 1 2 , 1886; 7 , Grant, KO. 4j7,081, Aug. 4. 1891; 8, Rogers, LIarch
Fig 5
1892; 9 , Archer, Feb. 28, 1893; I O , Ladd, KO. 5 j 0 , 8 3 1 , Dec. 3, 1895; 11, Barker, No. 577,638, Feb. 2 3 , 1897; 1 2 , Burrows & Weaver, No. 672,888, April 30, 1901; Musker & Hay, No. 676,096, June 11, 1901. Detailed examination of the Bone paper reveals 22,
Fie. 4
general though only the first claim in each case is quoted, there being three claims for the first patent a n d five for the second. CLAIM I , U. S . P A T E N T No. 755,376 TO LUCGE.
only one structure or apparatus not used or specifically described b y Lucke, and that is the porous diaphragm in place of the broken refractory material. “The method of burning explosive gaseous mixtures which consists in causing the mixture to move with a velocity greater There appears to be, however, no essential difference than the rate of propagation of inflammation through the mix- between a porous diaphragm and a body of broken material except in the shape or size of the passageture, and then reducing the velocity t o the rate of propagation of the inflammation and preventing diffusion with other gas, by ways open t o the flow of the gaseous mixtures. causing the mixture t o spread out so t h a t the successive surI n view of these experiments, the wide-spread faces of uniform velocity shall have adjacent points in any and apparently general acceptance of the supposition such surface a t substantially the same distance from the place that Bane’s work is new seems difficult t o support. where spreading begins, and burning the mixture a t the sur- Apparently, the only journal that has not fallen into face at which the velocity is equal t o the rate of propagation this error is “Power” which in its issue of Nov. of inflammation, substantially as described. ” 2 1 , 1911, calls attention to the similarity of Lucke’s and Bone’s processes, editorially. CLAIM I, U. S. PATENTNo. 755,377 TO LUCKE.
“The method of burning fluid fuel which consists in causing the fuel and a suitable combustion-supporting gas in proportions such t h a t there will be an excess of fuel over the quantity required for perfect chemical combination with the oxygen of the supporting-gas to flow into a hot combustion-bed, the supporting-gas moving with such velocity as t o cause the resulting mixture to move with a velocity greater than the rate of propagation of inflammation through the mixture, and the combustion-bed being of such a nature as t o cause the mixture to spread nut so that the successive surface of uniform velocity shall have adjacent points in any such surface at sub-
PHYSICAL-INDUSTRIAL CHEMISTRY.
At first sight i t seems as though the two divisions of organic chemistry and inorganic chemistry covered the whole field and as though a man who was well posted in these subjects would have all the knowledge. of pure chemistry needed b y one going into industrial chemistry. This is not true because the organic chemist and the inorganic chemist of the colleges
