l.\-DCSTRISL -4SD EiYGI,VEERISG CHEMISTRY
July, 1925
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Alcohol Motor Fuel from Molasses 11--Use of Alcohol and Alcohol-Ether Mixtures as Motor Fuels’,’ By E. C. Freeland and W. G. Harry i 2 1 LOWERLINE ST.,NEWORLEANS, L a , .qwD GEORGETOWS. BRITISH GDIANA
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Disadvantages of Alcohol as a Motor Fuel OSSIDERABLE research work has been clone on the and the data a properties and use Of I-Being of low volatility, an explosive mixture of air and alcoaccumulated will no doubt st’imulate interest in this hol vapor is difficult to create in cold weather; hence there is important subject, as alcohol has proved in many respects a difficulty in starting the engine when “cold.” I n tropical counmore desirable fuel than gasoline. Notwithstanding the en- tries there is very little difficulty in this respect. 2--.An explosive mixture of alcohol and air is formed in a very couragillg results of these experiments, holvever. only a few different ratio than that of air and gasoline, the former being ellgines specially designed for alcohol fuel have been placed from 9.5 to 11.5 parts of air to one part of alcohol, by weight; and on the market, because gasoline is cheaper than alcohol in the latter from 15 to 23 parts of air to one of gasoline by weight, nearly all the countries where a large number of internal coin- when used a t the same compression. 3--.An explosive mixture of air and alcohol vapor is formed bustion ennines are used and the use of alcohol fuel is rewithin narrower limits than stricted to those sections the mixture of air and gasothat are remote from sources line; consequently the engine of petroleum. On this achas a much lower speed flexiAlcohol and alcohal-ether mixtures can be successbility. count practically all the alfully used as fuel in engines designed for gasoline or kercoliol fuel consumed today Use of Alcohol and Alcoosene, without making any radical changes in the i? being used in engines origengines, and in some respects the new fuels are superior hol-Gasoline Mixtures inally designed for gasoline to petroleum products. In order to obtain maximum Many chemists and enor kerosene, and this situefficiency, a few adjustments must be made and certain gineers interested in alcohol ation will continue until the precautions taken. fuels seem to think that the prices of the two f u ds are Methods of securing best results under ordinary use of alcohol alone or almore nearly uniform or unoperating conditions are discussed and the authors’ cohol with a sman admixtil the number of engines experiences with alcohol and alcohol-ether motor fuels ture of gasoline is not practiniaterially increases in those are given, together with results of practical tests on cable, the general belief becountries that are using alautomobiles, tractors, and stationary engines, using ing that radical changes cohol. these fuels under varying operating conditions. must be made in the carDuring the past three buretor and that even then years the writers have conthe alcohol burns incomducted a number of experinient’s on the substitution of alcohol motor fuel in engines de- pletely, forming products of a foul and acid character, which signed for gasoline. These experiments have been carried out soon cause pitting or corrosion of parts of the engine. Alin a practical way, in order to reproduce exactly the same condi- though the use of alcohol alone is attended with certain diffitions under which the ordinary gasoline engine is operated. culties, the writers cannot entirely agree with these opinions This paper presents the results of these trials and also the most as far as the use of alcohol in tropical countries is concerned, important points which have come under the writers’ observa- because the results of a number of trials, some of which have extended over several years, have proved that for a certain tion in connection with the successful use of alcohol fuel. class of internal combustion engines alcohol will give entire Advantages of Alcohol as a Motor Fuel satisfaction. 1-The raw material for its manufacture is annually reproIf it is desired to use alcohol without admixture of benzene duced by nature and hence there is an inexhaustible supply. or ether, in motor car engines, 10 to 15 per cent of high-grade 2-Its storage and use is less restricted by insurance regulations gasoline and 0.5 to 0.76 per cent of pyridine or aniline should than gasoline, and fires can readily be extinguished with water. be added. Although alcohol without gasoline may be used, 3-It generates less heat by combustion and consequently requires less cooling water. the gasoline increases the volatility of the mixture, thereby 4-The cylinder temperatures are low-er, thereby preventing giving more satisfactory results. The pyridine or aniline cylinder lubrication difficulties. safeguards against the formation of free acid products, besides 5-The rate of flame propagation is less and the pressure more acting as a denaturant. The writers know of a case where nearly uniform through the entire stroke of the piston, resulting a tractor engine was badly corroded by the use of alcohol in smoother operation, less vibration, and the absence of preignition knocking. alone, whereas other tractors, running on the same grade of 6-When used in gasoline engines the engine will develop from alcohol mixed with 0.5 per cent pyridine, did not show any 10 to 20 per cent more power than when gasoline is used, and a t corrosion after being operated for nearly two years. There any one compression it gives a greater thermal efficiency than is less likelihood of corrosion if the alcohol is of high strength gasoline. i-There is very little or no deposit of carbon on the cylinder (95 to 96 per cent) and low ester content, as the combined walls of the engine. 8-It can be used a t much higher compressions than gasoline action of water and esters causes corrosion, due to the hydrolysis of the esters into their corresponding acids. without danger of preignition, thus resulting in greater thermal efficiency. The best compression pressure for gasoline is about i o When changing over from gasoline t o alcohol the motor car pounds per square inch; whereas for alcohol i t is 180 pounds per engine should be thoroughly cleaned before the alcohol is square inch. used. This point, although of paramount importance, i5 Presented before the Section of Gas a n d Fuel Chemistry a t the 68th very often overlooked, and this negligence soon causes carMeeting of t h e American Chemical Society, Ithaca, N. Y . ,September 8 to 13, buretor trouble. Certain poor grades of gasoline deposit a 1924. resinous substance in the supply tank, feed pipes, etc., * For P a r t I of this article see THISJOCRNAL. 17, 615 (1925).
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INDUSTRIAL AND ENGINEERING CHEMISTRY
in addition to the usual amount of road dust and a certain amount of rust, and when alcohol is used without first removing this deposit, the resinous matter is partially dissolved a n d the whole of the deposit is swept through the feed pipes. It is then not long before the carburetor jet is clogged and the alcohol is blamed for what is really the fault of the gasoline. After thoroughly cleaning all the parts mentioned, it is a good plan to allow alcohol to drip slowly out of the carburetor by opening very slightly the cock on the feed line, in .order to insure a thorough cleaning of the feed pipe and carburetor. If the carburetor float is made of cork, it should be coated with some substance that will render it impervious to alcohol, such as paraffin, gum tragacanth, gum arabic, or waterproof glue. The best method, however, is to replace the cork float with a metal one before the alcohol is used, as the substances used to coat the cork float will gradually wear off, owing to the solvent action of the alcohol and water. By substituting a metal float for the cork one in the beginning, all possible float trouble is prevented for all time. Owing to the higher viscosity and lower calorific value of alcohol as compared with gasoline, a larger carburetor jet opening must be provided for alcohol. In certain types of carburetors the jet itself, being of a fixed size, must be changed; the jets in other carburetors can be altered a t will. The l a t t e r type are the most satisfactory for alcohol fuel, as they can be easily adjusted to give best results. With equal thermal efficiencies,the fuel consumption of alcohol will be about 50 TDIPERAIURZ DLoRlls C u l i O P D S Comparative Curves Showing Variation per cent more than that of Vapor Tension with Temperature of gasoline, as the gross calorific value of gasoline is about 125,000 B. t. u. per U. S. gallon, while that of 95 per cent alcohol is about 80,500 B. t. u. per gallon; so that about 50 per cent more alcohol must be admitted into the cylinder per suction stroke of the engine. Alcohol requires from 9.5 to 11.5 pounds of air per pound of fuel, whereas gasoline requires 19 to 23 pounds air per pound; hence the air supply for alcohol must be considerably reduced. This regulation of the air supply is best accomplished while the car is in motion, so that the operator may easily see the change brought about by different mixtures of air and alcohol and regulate the air supply accordingly. The adjustment of the air supply while the car is in motion may be easily made by connecting the air throttle on the carburetor with a separate operating rod with a threaded end and thumb nut located on the instrument board of the car. Preheating the air supply by means of the exhaust gases may prove beneficial, especially if the carburetor is found to be very cold after the engine has been running for some time; for if the carburetor becomes too cold complete vaporization does not take place. In no case should the air supply be excessively warm, however, as an increase in the fuel consumption results. It is estimated that by preheating the air to 121" C. (250" F.), the maximum horsepower is decreased about 15 per cent, both for alcohol and gasoline.
Vol. 17, No. 7
At an atmospheric temperature of about 27" C. (80" F.) no difficulties have been experienced in starting motor car engines with denatured alcohol or a mixture of alcohol and gasoline although a t much lower temperatures the use of these fuels will no doubt cause trouble in this respect. I n order to start the engine quickly, a comparatively rich mixture of alcohol and air should be admitted into the engine cylinders, and after the car has attained a speed of about 15 miles per hour the air throttle should be gradually opened until a further opening causes a diminution of speed. It is obvious that the more the charge of alcohol is diluted per suction stroke of the engine, the better will be the thermal efficiency a n d likewise the fuel economy, provided the air supply is not increased beyond the optimum amount. By a few trials the maximum amount of air that can be used without impairing the working of the engine is easily found. The greatest difficulty when using alcohol and alcoholgasoline mixtures has been lack of flexibility of the engine a t low speeds. Between speeds of 20 and 25 miles per hour no trouble has been noticed, but when, after running slowly, an attempt is made to accelerate quickly the engine gives trouble. This is especially noticeable when the car has been slowed down on approaching a sharp curve in the road and after the curve has been passed an attempt is made to increase the speed suddenly. Kotwithstanding this difficulty, however, with careful operation alcohol will give fairly satisfactory results in automobile engines. An increase of about 50 per cent of fuel consumption over medium grades of gasoline can be expected. On a run of 104.5 miles one of the writers secured an average mileage of 12.6 per U. S. gallon, using a mixture of 92 parts of 94 per cent alcohol, 7.5 parts of gasoline and 0.5 parts of pyridine, as compared with 18.9 miles per gallon of gasoline on an 894-mile test. Placing the heat value of the alcohol mixture a t 83,500 B. t. u. per U. S. gallon and that for gasoline a t 125,000 R. t. u. for a similar quantity, the heat consumption is 6627 B. t. u. per mile for alcohol and 6614 B. t. u. per mile for gasoline-equal thermal efficiencies, showing that there is complete combustion of the alcohol. Alcohol can be used more successfully in tractors and other engines running a t almost constant speeds than in motor car engines. For such use no large admixture of gasoline is necessary; a mixture of alcohol with 0.5 per cent pyridine and 1 per cent gasoline or kerosene giving satisfactory results for considerable periods of time in a number of different types of tractors, besides large motor trucks and Delcolight engines designed for kerosene. In no case was there corrosion of the engine parts, and in all cases the cylinders were especially free from carbon. When first tried out in tractors, the alcohol fuel consumption was about 50 per cent higher than for gasoline or kerosene, but later this figure was decreased by better manipulation, until the excess of alcohol over the other fuels amounted to about 33.3 per cent, thus showing a higher thermal efficiency for alcohol. A slight advance of the ignition has proved advantageous and no device for preheating the air is used. One of the writers recently conducted a test on a %kilowatt, 115-volt Delco-light engine designed for kerosene, using two different brands of this fuel and also alcohol denatured with l per cent kerosene and 0.5 per cent pyridine. The results of this comparative test are as follows: Current generated by 1 U S gallon A kerosene Current generated by 1 U S gallon B kerosene Current generated by 1 U S gallon alcohol Increased consumption of alcohol to equal output of current with A kerosene Output of current per hour, using A kerosene Output of current per hour using B kerosene Output of current per hour' using alcohol Increased output of curreni per hour on alcohol as compared with A kerosene
Watts 1891 1450 1599
15 2 = 0 79 per cent 1904 8 1497 9 1920 0 15 2 = 0 79 per cent
IiVDliSTRIAL A N D ENGINEERING CHEMISTRY
July, 1925
This is a further demonstration that equal power output can be secured with internal combustion engines using alcohol, when operating on a consistent full load or high percentage of full load a t constant speeds. Alcohol-Ether Mixtures
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For use in automobiles and other engines that operate under Yariable speed and power conditions, the addition of ether to the alcohol improves the fuel considerably, because of its great volatility and high thermal value, besides its ability to burn completely with a wide range of air mixtures. Mixtures of alcohol and ether carburet readily even a t low temperatures, and there is no difficulty in starting the engine from cold. The fuel required for machines and tractors controlled by the manufacturer is quite different from that required for the open market. In the first case fuel of only a fair quality may be used with success, because it is easy for the experts of the concern to supervise the motors to see that they are adjusted properly; whereas, for the open market a fuel of the highest quality should be produced so that the motorist may be able to use it with the minimum amount of engine adjustment and secure highly satisfactory results under the usual operating conditions. These are the main differences between the use of denatured alcohol and alcohol-ether mixtures in motor car engines. Although the former will prove satisfactory to some drivers, the experiences of a few careless ones will discourage others from using it instead of gasoline. The superiority of the alcohol-ether fuel over alcohol alone lies not only in its greater mileage value, but also in the fact that it is less likely to give unsatisfactory results under poor operating conditions. The same precautions as to cleaning the car before changing over from gasoline to the ether mixture must be observed as when using alcohol, although it will be found that the ether dissolves the higher hydrocarbons which are insoluble in alcohol, thus effecting a thorough cleaning of the parts that are coated with resinous compounds. The carburetor jet area must also be increased, according to the composition of the mixture used, and it is advisable to preheat the air supply because the carburetor is rapidly cooled by the evaporation of the ether. The proportion of ether to be mixed with the alcohol depends on local conditions, and no given mixture can be regarded as the best fuel for all countries. Climatic conditions, cost of the ether as compared with the alcohol, and mileages obtained for different proportions of ether are the chief factors in determining just what mixture is most satisfactory. Inasmuch as the aim of the motor spirit manufacturer is to produce a fuel that will operate a car at the lowest cost per mile, the most efficient way of determining the value of any given mixture is on a cost-per-mile basis, consistent with ease of operation. If a represents the cost per gallon of alcohol, A the percentage of alcohol in the mixture, likewise e the cost per gallon of ether and E the percentage of ether, then the cost per mile will be
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aA eE Total mileage
For tropical climates mixtures containing as low as 20 per cent ether by volume will be very satisfactory as far as ease in starting the car and flexibility of operation are concerned, so that the proportion of ether over 20 per cent will depend on its cost and the extra mileage obtained by larger admixtures. The writers carried out a series of tests, using several mixtures of alcohol and ether, to compare’ the mileages obtained with varying proportions of ether. A 1-gallon tank was attached to the side of a Ford five-passenger car to serve as the fuel supply tank. For each test 1 pint of the fuel in the fuel
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supply tank was measured out, the car then started and kept in motion a t a speed of about 20 miles per hour until the fuel was exhausted. In order to eliminate the wind factor, a circular track was chosen for the trials, so that equal distances were traveled with and against the wind. The car was equipped with a Holley “NH” model carburetor, which had no special adjustment for the alcohol-ether mixtures other than a variation of the fuel needle valve to suit the flow of each grade of fuel used. I n order to compare the different alcohol-ether mixtures with standard gasoline, several trial runs were made using gasoline under exactly the same conditons as when using the different alcohol fuels. With the fuel needle valve opened turn, the average mileage per U. 5. pint of gasoline was 1.96 miles. This adjustment of the needle valve was found to give the highest mileage. The alcohol-ether mixtures had the following composition: J
Mixture
Alcohol
PER CENT BY VoLumE Ether Kerosene
Pvridine
With the fuel needle valve opened to 1 turn the average mileage obtained per pint of Mixture 1was 1.94 miles. Using the same adjustment of the fuel needle valve (open 1 turn) for Mixtures 2 and 3 as with Mixture 1, the average mileages obtained were 2.0 and 2.08 respectively. When Mixture 4 was tried, the fuel needle valve was varied during the several runs. With an opening of ’/a turn the mileage obtained was 1.92 per pint. An opening of 1 turn gave 2.08 miles per pint, while an opening of 1 1 / ~turns decreased the mileage to 2.0. Although the results obtained in these tests do not give accurate mileage figures per gallon of fuel, owing to the small quantity used and the necessity of using part of each pint for starting the car (which is in this case a comparatively large percentage of the total quantity for each test); nevertheless, they show the gradual increase in mileage as the proportion of ether is increased. The mileage secured from a given mixture depends largely on the adjustment of the fuel needle valve; or in the case of carburetors having jets of a fixed size, on the size oi jet used. This fuel valve opening must be varied, of course, depending on the composition of the mixture used. If the fuel opening is not large enough, the mixture in the cylinder becomes too lean and low mileage results. Likewise, if there is too much fuel going into the cylinder per suction stroke of the engine, the fuel consumption is also increased. Results of trials with varying fuel valve adjustments are a s follows: COYPOSITIOH OF Alcohol Ether Gas oil Pyridine
Test
1 2 3
FUEL
Per cent b y volume 59.5 39 1
0.50 RESULTSOF TESTS Carburetor adjustment Open mileage per U. S. gallon 18.23 19.17
20.50
This represents the average mileage obtained from several runs, using half-gallon portions for each test. The carburetor adjustment for Test 3 was made as follows: With the carburetor on same adjustment as for Test 2, the car was accelerated to 25 miles per hour, and with the throttle remaining. in this position the carburetor needle valve was adjusted ta give maximum speed of the car. The speed was then kept at from 20 to 25 miles per hour until the end of the test. The best mileage obtained with gasoline on the same date was 22.5 miles per gallon, using half-gallon portions. When using gasoline the carburetor needle valve was adjusted ta
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ISDCSTRIAL A S D E S G I S E E R I S G CHEMISTRY
6/g turn open, in the same way as for Test 3 on the alcoholether mixture. The speed was kept a t 20 to 25 miles per hour. With 22.5 miles per gallon of gasoline as the standard, the excess fuel consumption of the alcohol-ether mixture over the gasoline, for a given mileage, is 23.8 for Test 1; 17.8 for Test 2; and only 10.2 for Test 3. I n order to verify these results over a long distance, a 240-mile test was made. The carburetor was adjusted to 1 turn for 120 miles and then changed to 11/4 turns for the remaining 120 miles. On the first half of the trip the average mileage secured from the alcohol-ether fuel was 16.67 per gallon; for the last part, the average miles per gallon was 19.81. These results show that a considerable saving of fuel can be effected by proper carburetor regulation. It is often claimed that alcohol fuel makes a very dry explosive and that therefore the cylinder lacks lubrication. Plenty of lubricant in the cylinder is essential; otherwise on stopping the engine, traces of unburnt fuel in the cylinder may start corrosion. I n some cases castor oil has been used with the alcohol-gasoline to overcome this difficulty. Other users of alcohol fuel have added larger quantities of pyridine, up to 2 per cent of the volume of the fuel, claiming that this larger quantity of pyridine solves the lubrication problem. I n the case of alcohol-ether mixtures, cylinder lubricating oil (usually about 1 per cent by volume) may be added to the fuel, as the oil readily dissolves in the ether mixture. A parallel case of maintaining cylinder lubrication by the addition of lubricants to the fuel is found in certain types of outboard motors, which receive their cylinder lubrication entirely by the addition of oil to the gasoline. I n the caseof the alcohol fuel, however, the lubricating system is operated as usual, the oil being added to the fuel to counteract the dryness of the alcohol. There will be no corrosion of engine cylinder walls by alcohol-ether fuel if proper precautions are taken. Both the alcohol and ether must be free from mineral or organic acids and the denaturant used must not be acid. The use of a slightly alkaline substance, such as pyridine or aniline, for denatura-
Yol. 17, No. 7
tion will safeguard against the possibility of small quantities of free acetic acid being formed by the combustion of the alcohol. In order t o prove that alcohol-ether fuel has no deleterious effect on a motor car engine, a new car was operated on this fuel for nine months, a t the end of which period the cylinders were examined for the first time. The cylinder walls were in perfect condition without a trace of corrosion, and there was no carbon deposit on them. A motor car expert expressed the opinion that the engine was in a much better condition than if gasoline had been used to operate it. The principal objections to the use of ether in motor fuel are its odor and high volatility. The odor of ether is very objectionable t o some persons, especially when the new fuel is first used, but people will become accustomed to it in a very short time. On account of the high volatility of the ether, the amount of it in mixtures of alcohol and ether gradually decreases, especially in the fuel contained in the storage tank of a motor car because of constant agitation. In one case the amount of ether decreased 10 per cent on storage for about three months. A decrease of this amount will sometimes take place from the time the tank is filled with fuel until it is exhausted, especially if the car is not operated very often. The use of alcohol fuel has received a number of setback>, due principally to a poor quality alcohol being marketed. This has naturally prejudiced consumers against the better grade fuel and has caused a slow development of the industry. At the present time, however, there is an increased tendency towards the marketing of the high quality product. A number of obstacles are yet to be overcome, but better methods of operating motor cars on alcohol and alcohol-ether fuel are coming into use and this increased efficiency is lowering the fuel consumption of engines and increasing the number operating on alcohol. Even with the present type of engines, alcohol is giving better thermal efficiency than gasoline; and it is certain that the fuel consumption ratio of the two fuels will be lowered as engines better adapted for alcohol are introduced.
Plantation Rubber Industry in the Middle East A valuable report has recently been published by the Department of Commerce, “The Plantation Rubber Industry in the Middle East,” which is a part of the survey of essential raw materials authorized by the Sixty-seventh Congress, and is the second of a series of publications to be issued on crude rubber. The first, entitled “Marketing of Plantation Rubber,” was issued in January, 1924. The geographical region covered in the new report-Ceylon, India, Burma, Malaya, the Netherlands Indies, Indo-China, British North Borneo, Sarawak, Brunei, S a m , and the Pacific Islands-produces 95 per cent of the world’s rubber. The economic factors surrounding the industry are discussed, special emphasis being placed on cost of production and the extent to which the future potential output from the present planted area can be relied upon to meet the world’s increasing demand. The book is splendidly illustrated, especially that portion having to do with production, where photographs of operations in the production of plantation rubber are shown from clearing of the jungle to shipment of the product. The work is also made more comprehensive by the inclusion of various maps, charts, and statistics. The report shows that material reduction in costs has been effected during the last few years by the adoption of altered methods, and points out the possibility of additional important savings by further reorganization. This is of interest in connection with the survey of the Department of Commerce in the Philippines and Latin America. The field work covered in this report occupied the period from June, 1923, to February, 1924. The report points ou(t that rubber requires a warm, moist climate, with deep soil of good physical texture. A rainfall of 70 inches is sufficient; 1600 feet is generally regarded as the highest altitude for rubber; and districts with winds of cyclonic force and frequent morning rains
should be avoided. The rubber districts of the Middle East lie in a region where temperature and rainfall are suitable and destructive winds practically unknown. The approved planting methods are clean clearing and removal of all timber and stumps; close planting with early thinning out, eventually to 70 or 80 trees per acre; and conservation of soil and rainfall on slopes by terracing, digging of pits, etc. Where competent scientific advice is available, budded stock and selected seed may be used as planting material. Crops interplanted in rubber are not regarded with favor. Daily tapping has been generally replaced by alternate-day tapping or periodic tapping. The almost universal limit is one cut per tapping. Important new developments in the preparation of plantation rubber have been introduced recently. There is sufficient evidence on which to base deductions regarding the economic life of a rubber plantation, and no prophecy can be ventured on the life of an estate planted on good soil and properly cared for from the start. The question of native-grown rubber was the most difficult encountered in this investigation. It seems fairly clear that native-owned rubber will become a factor of more and more importance in stabilizing the industry, because of the comparative ease with which native producers can cease producing rubber during low prices and divert their attention to other crops, or, on the other hand, concentrate on rubber production during high prices by adopting more intensive methods than would be countenanced by Europeans. -The relative merits of the various countries under investigation are compared with respect to initial cost of leasing land, climatic conditions, political situation and labor legislation, labor supply and turnover, wages and cost of recruiting, efficiency of labor, . .comparative costs of production, taxation, and exchange.
