Spontaneous Combustion of Egyptian Sugar Cane Molasses A Review of Naus Bey's Report
C. A. Browne Bureau of Agricultural Chemistry and Engineering U. S. Department of Agriculture Washington, D. C.
Can* molasses overflowing tank at Ermant sugar factory· Egypt, of spontaneous decomposition ARIOUS papers have been published by the reviewer upon the composition, keeping qualities, and spontaneous decomposition of sugar cane molasses. While the observations reported relate to molasses of domestic and Cuban origin, information upon the liability of cane molasses to undergo rapid spontaneous chemical changes during storage has been communicated to him by the technologists of other countries. During a visit made to various cane sugar factories of Egypt in February» 1930, the reviewer was informed by the late Naus Bey, director general of the Société Générale des Sucreries et de la Raffinerie d'Egypte, that the molasses from some of their factories, when stored in open earthen reservoirs, frequently underwent a process of internal combustion, which soon reduced the product to a porous carbonaceous mass. He attributed this decomposition to the action of the intense Egyptian sun during the long hot summer and stated that molasses stored in tanks did not undergo this violent change. Lately, through the good offices of Prinsen Geerligs of Amsterdam, the reviewer has acquired a detailed report, with photographs, that had been prepared by Naus Bey a short time previous to his death, upon the behavior of Egyptian sugar cane molasses during storage. The report and photographs are of so striking a ciiaracter that a brief abstract of the material is herewith presented. There are five sugar factories in Egypt. Two of these. Nag-Hamadi and AbouKoorgas, employ the process of diffusion of bagasse and simple defecation; a third factory, Cbeikh-Fadl, employs diffusion of the sugar-cane cossettes, the process in other respects being the same as for Nag-Hamadi and Abou-Kourgas; the two other factories Ermant and KomOmbo operate by sulfidefecation. The phenomenon of rapid spontaneous combnsrtion was confined to the molasses of
V
a result
the last two factories, whose process of sulfidefecation was performed as follows: The mixed mill juice, after screening, was limed and then sulfured. The liming was performed either cold, the contents of each tank being brought to a certain alkalinity before sulfuring, or hot, in which case the liming and sulfuring were practically continuous, the sulfur dioxide treatment following the addition of lime by only a few seconds or being applied at the same time. The molasses from this process showed all ranges of decomposition during storage from annual losses of only 2 to 3 per cent sucrose to violent alterations in which all of the sugar was destroyed. These changes in the later stages were accompanied by an ebullition of the molasses with ejection of steam, acrid fumes, and masses of viscous fluid, and then, as the heat increased, by a carbonization of the material to a porous cokelike mass, this latter manifestation being confined: mostly to molasses stored in earthen reservoirs. The following abstracts from Naus Bey's reports will give an idea of the intensity of these spontaneous changes. The first case cited is that of the spontaneous decomposition of molasses in a tank at Ermant plantation in the spring of 1938. The tank, which had a capacity of about 5000 tons, was cleaned before the campaign, whitewashed on the inside with lime, and filled with molasses between February 25 and March 20. On March 29 patches began to be noted on the surface of the molasses and on April 9 evolution of gas and blackening were observed at one of these places. The temperature at this point was 58° C , which was some 30° higher than at other points of the surface and near the bottom where decomposition had not started. The sucrose content and purity of the molasses at the point of decomposition were toss than half of those at the other places, which retained their normal alkalinity while the decomposed area 734
had become perceptibly acid. Decomposition spread finally throughout the whole tank, and on May 16 the evolution of gas became so strong that the molasses began to overflow and run down the outer walls of the tank, as shown above. The temperature of a sample taken at the surface was 69° and at the bottom, 64°. On May 20 the frothing increased and acrid fumes were given off. In order to quiet the reaction, water was pumped onto the surface of the molasses, but this was ejected without lowering of the temperature. On May 21 so much molasses had overflowed from the tank onto the surrounding land that a cemetery wall gave way and various gardens were flooded. Finally, on May 22, approximately 324 tons of water were forced into the tank by high-pressure pumps which brought the reaction to an end. The molasses, although diluted with 7 per cent water, was three to four times more viscous than normal molasses. It was believed that, if the water had not been added, the whole contents of the tank would have carbonized to a solid mass, after the manner of cane molasses stored in open reservoirs. Chemical analysis of the decomposed molasses after dilution showed the following: water, 31.34 per cent; sucrose, 2.64 per cent: reducing sugar, 22.01 per cent; ash, 18.31 per cent; organic nonsugars, 25.70 per cent. The phenomena attending the carbonization of molasses in open reservoirs are much more striking. These changes occur between June and November when the dark-colored molasses on exposure to the hot tropical summer sun acquires naturally a temperature much higher than that of the surrounding atmosphere and far exceeding that of the old sugar-house hot room where the so-called froth fermentation of molasses was very likely to occur. The hot molasses then begins to décomposa spontaneously and
DECEMBER 10, 1939
NEWS EDITION
to the heat absorbed from the sun is added that generated by internal com bustion. The observations of a case of rapid spontaneous decomposition of mo lasses in an earth reservoir at Kom-Ombo are cited. In the spring of 1931 fresh molasses was emptied into the reservoir. On July 27 the temperature began to rise and samples taken weekly showed a progressive deterioration as may be seen from the following table: Tra-
1931 August 3 August, 11 August 17 August 24 August 31
APPABKNT REDUCING PBRAB B I X S u c a o e a SUGABS T U B S
94.82 94.40 93.71 93.52 93.32
22.0 20.8 20.8 19.7 16.0
23.8 23.8 22.7 21.9 19.2
65° 57° 62° 67° 73°
Early in September steam began to be evolved from the surface of the lake of molasses. Ebullition then commenced with ejection of stringy jets of molasses and the reservoir overflowed its walls. Next, as the heat became more intense, there were internal explosions with the dis charge, to several meters' height, of car bonized material that had lost all the char acteristics of a fluid. Finally, during the night of September 7 to 8, the whole reservoir of molasses solidified to a car bonaceous mass. When it had cooled the carbonized molasses consisted of a porous hard material, resembling coke and having a dark chestnut color. It was difficult to break up with a pick and when crushed gave off a strong characteristic empyreumatic odor. A sample of the car bonized molasses in the case just cited analyzed October 29, 1931, showed the following composition: moisture, 11.17 per cent; ash, 18.25 per cent; carbon, 21.15 per cent; and volatile matter, 49.43 per cent. The carbonized molasses was used as a fuel, one sample which was tested having a thermal value of 5336 calories. The report of Naus Bey [on the basis of the observations made in Egypt and of the results obtained by Browne (1), by Honig (2), and by Kopfler (5) in other countries] discusses the possible causes of the carbonization of Egyptian molasses and of the means for its prevention. Of the possible factors involved in this type of deterioration six may be considered : method of manufacture; composition of
735
the nonsugar of the molasses; reaction of the molasses; microorganisms; concen tration; and temperature of storage. Method of Manufacture. Since the two factories where carbonization of molasses occurred both employed sulfidefecation, it might be inferred that the use of sulfur dioxide in clarification was the chief contributing factor. It was pointed out, however, that in other cases where sulfidefecation was used no de terioration occurred, so that while the use of sulfur dioxide in clarification no doubt favored this type of deterioration other factors had to be taken into account. Composition of the Nonsugar. A comparison of the analyses of a stable molasses which did not carbonize and of two unstable molasses which did car bonize showed certain distinctive differ ences. STABLB MOLASSES
Water Ash Organic nonsugars Total nitrogen Nitrate nitrogen
21.00 13.30 12.7β 0.308 0.064
UNSTABLE MOLASSES
19.50 13.12 17.27 0.455 0.084
12.8Θ 14.40 27.30 0.688 0.127
The results show much higher total solid, organic nonsugar, total nitrogen, and nitrate nitrogen contents in the two samples of molasses which carbonize than in the one sample which did not carbonize. The variations, while marked, were not regarded as significant except in case of total solids. Reaction of Molasses. A single test in February, 1938, showed that the two factories where carbonization was most marked manufactured molasses that was alkaline to litmus, whereas the three factories where carbonization did not occur manufactured molasses that was either neutral or acid to litmus. The results were regarded as indicative but not as conclusive until more tests could be made on other samples. Microorganisms. The supposition that microorganisms produced such drastic alterations as those observed in the spontaneous carbonization of molasses was definitely rejected. Concentration. The fact that the molasses which showed the greatest tendency to carbonize were all of low moisture content led to the conclusion that overconcentration was the chief
factor involved in the spontaneous de composition of Egyptian molasses. In stead of boiling the molasses to 44° Bé. or over, it was recommended that the concentration be not allowed to exceed 42° Bé. Temperature. The temperatures employed in the processes of manufacture were not regarded as having any effect on the keeping quality of the molasses. The heating of the dense molasses destined for storage in order to increase its fluidity and ease of handling was considered, however, as an important factor in promoting spontaneous decomposition, especially in the large open reservoirs where the molasses received additional increments of heat from the hot tropical sun. It was pointed out that whenever the molasses was stored cold deterioration did not take place. Reduction of the high concentration of solids and avoidance of too high a temperature at the commencement of storage were the two chief means recommended for preventing the spontaneous carbonization of Egyptian cane molasses. The possible nature of the chemical factors involved in the spontaneous heating and carbonization of molasses was not considered in Naus Bey's report. The investigations of the reviewer upon the spontaneous decomposition of cane molasses during storage nave led him to the conclusion that the chief factor of importance in this connection is the formation of highly labile unsaturated organic nonsugars of high carbon content. These are produced from the sugars by a process of dehydroxylation, as is proved by the progressive increase in the carbon content of the nonsugars of cane sirup and molasses during manufacture and storage. The mineral salts of cane molasses, when the latter is concentrated, no doubt play a prominent part in this process of dehydroxylation, in which the formation of enolic compounds is in all probability a preliminary step. The continued stripping off of hydroxyl groups from the sugar molecules leads not only to the loss of total sugars encountered in this type of decomposition but to the accumulation of unsaturated carbon compounds of high exothermic reactivity. When this stored-up energy starts to be released the temperature (already excessive) of the molasses begins rapidly to increase with the loss of more and more combined water until finally, by sudden internal chemical readjustments, the whole mass with almost
Ebullition o£ cane molasses in an open reservoir undergoing spontaneous decomposition, showing increasing intensity preceding solidification to a carbonaceous mass.
736
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
explosive violence is converted into a porous cokelike carbon. The role which insignificant amounts of mineral matter play in reactions of this kind is indicated in the familiar trick of setting fire to a lump of sugar. The lump will not ignite on application of a lighted match but if a speck of tobacco ash be added the sugar will readily inflame. It i s undoubtedly the dehydroxy lation. produced by the catalytic action of tne ash, that brings the carbon t o a state where it can be ignited. In the making of decolorizing carbons from sugar cane molasses by the action of sulfuric acid, dehydroxylations and violent reactions, similar t o those observed in the spontaneous carbonizations occurring in Egyptian molasses, have been reported. Quantitative studies of the action of the various salts and organic nonsugars occurring i n cane molasses upon known mixtures o f sucrose and reducing sugars at high concentrations and different temperatures are greatly desired for the light which they will throw upon problems of this kind.
The Chemists' Club Library
Automobile Gasoline a n d Lubricating Movies
F
ROM modest rjejnnnings in 1898, the library of The Chemists' d u b (N. Y.) has grown until i t comprises some 55,000 volumes, including books, journals, pamphlets, and dissertations treating of chemistry and allied subjects. Technical journals constitute nearly 75 per cent of the entire collection and include 165 complete sets of journals and over 1500 incomplete files. The library subscribes to more than 200 chemical journals, in addition to many which are received from Chemical Abstracts. In 1899, the library of the AMERICAN CHEMICAL SOCIETY was deposited with
the club, and the following year the American Section of the Society of Chemical Industry added its collection to those of the club and of the AMERICAN CHEMICAL
SOCIETY. Gifts, bequests, and purchases through the years have accounted for the constant growth in quantity and importance of the library's files, notably the purchase, in 1913, of the library of Frederick Schniewind, comprising over 4800 volumes. Literature Cited Like the Library of Congress, the Chemists' Club Library has its "rare book" sec(1) Browne, C. A. t J. Am. Chem. Soc.% 4 1 . tion which includes rare and early works 1432-40 (1919); I N D . E N G . C H E M . , on alchemy, as well as on subjects which 21, 600-6 (1929); Quart. Natl. Fire time and science have proved to be more Protect. Assoc, April. 1934; Proc. serious. These rare books include early Intern. Soc. Sugar Cane Tech., 5 , printed works dating back as far as 1526 2 1 6 - 2 7 (1935). and authors dating back to the first cen(2) Honig, P., Proc. Intern. Soc. Suoar Cane tury of our era. Agricola is the earliest Ttch.. 5, 228 (1935). of these ancient authors and among his (3) Kopfler, K. W., Proc. Cuban Sugar Tech. companions on the rare book shelves we Assoc., 10. 6 9 - 7 5 (1936). find such names as those of Paracelsus and Glauber. Presented before the Division of Sugar ChemAlthough the library is intended, priistry and Technology at the 98th Meeting of the marily, for use as a reference library by Amerioan Chemical Society, Boston, Mass. members of The Chemists' Club, the
HE latest technical advances in the T manufacture of gasoline and lubricating oils are illustrated in three motion picture films recently revised and reissued by the Bureau of Mines, Department of the Interior. Supplementing photography in showing oil-field, pipeline, and refinery operations, animated drawings are used to make plain the chemical and physical processes employed in oil refining and the thorough lubrication of an automobile. Film 99, "The Story of Gasoline", takes the observer on a tour through a modern refinery and shows equipment used in converting crude oil into motor fuel by the use of heat and pressure. Film 120, "The Story of Lubricating Oil", illustrates diagrammatically the principal s t e p in t refining the two primary sources of lubricating oil, "distilled lube stock" and "residual or bottom lube stock", the methods of removing paraffin wax, and its transformation into useful products. Film 151, "Automobile Lubrication", shows the importance of proper lubrication in reducing friction in machinery. Copies of these films are available in the 16-mm. size for exhibition b y schools, churches, colleges, civic and business organizations, and others interested. Applications should be addressed to the Bureau of Mines Experiment Station, 4800 Forbes St., Pittsburgh, Penna. N o charge is made for the use of the films, but the exhibitor is expected to pay transportation charges.
AMERICAN CHEMICAL SOCIETY, and the
F i v e Oil C o m p a n i e s J o i n i n N e w Aviation F u e l P r o d u c t i o n OOLING independent results of their research starts, five leading oil comP panies have combined for large-scale production of 100-octane aviation gasolines directly from paraffin and olefins by a basically new development using sulfuric acid as a catalyst, according t o reports from the American Petroleum Institute. To assure large quantities of the fuel, so vital t o national defense, with a minimum of dt?lay and waste of correlative experience, the Anglo-Iranian Oil Co., Ltd., Humble Oil and Refining Co., Shell Development Co., Standard Oil Development Co.» and The Texas Co. are joining to operate six alkylation plants with annual capacity of about 37,000,000 gallons. Eipjit additional plants with total annual capacity of around 125,000,000 gallons are under consideration. Although the 1938 consumption of aviation gasoline was 20,000,000 gallons, considerably less than the output planned by the new method, i t s use has increased 13,000,000 gallons since 1937. Continual rapid gains are expected in 1939 and 1940. The methods developed in the five companies, while differing in detail and results, were essentially similar in principle. The new refining process, using standard equipment, permits transformation of lighter hydrocarbons and olefins into large quantities of blending stocks for 100-octane fuel, particularly suitable for airplane use because of their high octane number, tow sulfur content, high calorific value, anci lack of sensitivity to different engine conditions. Low operating costs, substantial yield, and the availability of sulfuric acid are said to assure reasonable prices.
VOL. 17, NO. 2 3
Society of Chemical Industry, the use of its material by any one interested is permitted. The use of the collection has grown to such proportions that the Lirarian, Miss Emily J. Fell, requires the help of two assistants to handle the work. The Library Committee of the club is headed by Nelson Lit tell, chairman, H. B. McClure, vice chairman, and Carleton Kllis, honorary chairman. Soap a n d Toiletry Exports U p
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^OREICÎN demand for American soaps and toiletries increased sharply in September, when exports advanced 44 per cent to about $1,000,000 compared with the corresponding month of last year, according to the Chemical Division, Department of Commerce.
Corrosion Behavior o f Silver UCH of the work of the American M Silver Producers' Research Project, discussed in the Tenth Progress Report recently published, has centered about corrosion. T o the Lehigh Fellowship has been assigned a systematic study of corrosion behavior of silver as compared with competing materials in specific industrial processes. An interesting feature of the research is the request for industry's cooperation. Companies having corrosion problems are invited to communicate with A. J. Dornblatt, the project's senior research associate, National Bureau of Standards, Washington, D. C , regarding arrangements to be made with the Lehigh Silver Research Fellow, J. M. Thomas, for investigating the possibility of solving their special problems by the use of silver.
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