Problems in Oxygen Gasification of Coal ,-
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1.1. Newman ond J. R MI%
Production of Synthesis Gas by Partial Oxidation
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............. .. Organic Acids from Colorado Oil Shale . . . . . . J. J. 1.E. Shale Oil Refining. . . . . . . . . . . . . . . . . . . . H. 0. Hopkinr, R. and W. Hydrofining Thermally Cracked Shale-Oil Naphtha . . . . . .
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Purification of Synthesis Gas
H. W. WdnwripM. 1. 1. Kame. M. W. Wilron, C. C. Shale, and 1. Ratwmy
W. E. Robinson,
Cummins, ond
C. Carpenter, C.
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Synthetic
Stanfield
E. Kalhy,
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I. R. Murphy
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P. 1. Coninsham, 1. C. Antweiler, L. G. Mmyfleld, R. E. Kallay, end W. P. C O ~ N
HAT will future ground transport fuels be like? To study and resolve the question, an understanding of future engine design is necessary. Each type of engine must consume fuels tailored to its particular needs; gasoline is &nentirely different product from Diesel fuel. Even with similar engines, fuels must he selected to meet individual engine requirements, baaed on environment aa well as design. ground transport engines fall into four groups (subject, o new design developments): gasoline, Diesel, gas d free piston.
Gasoline Engine! nnportant motor gasaline properties include octane number, volatility, and ahility to burn without leaving harmful deposits on engine pa-. Efficiency, measured by work output pe: fuel unit consumed, is a function of compression ratio in the Otto cycle engine. Compreasion ratio increase &o results in higher cycle temperatures and pressures and greeter uncontrolled combuation (“spark knock”). Hydrooarbons differ in their resistance to knockreflected in their “octane number.” Some chemical additives inerebe their knock resistance, tetraethylled being the best known. The detinite relationship between efficiency,compression ratio, and fuel octane number is well known to both engine designer and fuel supplier; both keep it in mind when planning engine design or fuel processing changes. To conform with a sound nationd economy, compression ratio and octiLne number changes must go hand in hand because of three factors: 1. Thc prtrolcum industry’s hrge capital inr.ciinieut and added processing coats M raise octane numher 2. Similar automotive industrv ewenw for deaim Ch3lXr c% 3. Resulting .cost of gasoline tb th;? consumer
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Current model American cars have an average compression ratio of 8.5:l (some go as high as 10: 1) and about 78% of these perform satisfactorily on average quality 97mtane fuels. Some cars require 100 or better octane rating, and the 1960 cam are expected to need 101 to 102 octane gasolines, a rating which can handle 11:l compression ratios. Although the di5erence between 97 and 102 octane may not appear large, such improvement is important from the standpoint of eJTiciency and represents appreciable added gasoline mufacturing coat. Autborities feel that an increase in compression ratio from 7: 1 to 12: 1 will save 20 to 30% in fuel economy for the m e performance. Recent yeam have seen rapid increase in compression ratio and octane number, but part of the engine efficiency gain has heen used up in added performance to satisfy consumer desires. The 12:l ratio is about the limit of present design, but developmentsmay change this.
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Current engine improvement studies include cornbustion cbember shape, hot spot elimination, fuel injection systems, better engine cooling, and improved transmission characteristics. Experience in the fuel m a shows that processes willbe developed t o make superior fuels at lower coat. An antiknock agent better than tetraetbylled may be discovered; perhaps an agent will be developed to augment its effectiveness. As in the past, economics dictate that there c o n h u e to be more than one g r d e of motor gasoline. Very recently a threegrade system has been introduced to supply high octane quality fuels to the new high compression engines. The highest gmde fuel will be in excess of 100 octane number. This is an important point far the chemical industry-premium fuels not only have higher octane numbers but often contain additives not always found in the Less expensive grades. An efficient carhureted-rLmifold engine requires a fuel, sufficiently volatile when mixc 1 r i t h air a t normal temperatures to give uniform mixture strenglh to all cylinders without needing excessive manifold heat wbicb can cause knock. Other important charaoterktiosare dependent on volatility--eese of starting, vapor lock, warm-up, crankcase dilution, and carburetor icing.
Wide Use of Fuel Injection Systems Means Fuels
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Of same premium octane quality Of relaxed volatility With no need far carburetor anti-icing additives
Gasoline quality contributes to sludge and crankcase deposits. Sludges, in turn, may interfere with the operation of engine parts such &B hydraulic valve lifters. Current research is directed toward reducing the amount of unburned material in gasoline exhaust-additives may prove of considerable importance.
Diesel Fuels Future Diesel fuel demands will be largely determined by changes in the automotive and railroad transportation fields. Some truck and bus fleet operators feel they’ll get bigger profits with gwline-powered vehicles, and the Diesel engine’s role is with heavy duty equipment, like earth-moving apparatus. The new MAN or “whisper” Diesel may revive interest in Diesels for lighter transportation. In it the combustion chamber is incorporated in the piston, and the fuel is sprayed onto the chamber walls. Claims are that it has these advantages over conventional Diesels:
IN- ~ ~ - - ~ A NA DL E N G I N E E R I N G C H E M I S T R Y
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Fuels a n d Chemicals Divisionsof Gas and Fuel Chemistry and Chemical Marketing and Economic% 128th Meeting, ACS, Minneapolis, Minn., September 1955 1. Operates on fuels from gasoline to D i e d oils without m i ficing performance 2. No Diesel knock, providing a quiet engine with elastic torque characteristics 3. Less soot formed per pound of fuel consumed a t part load 4. Lube oil contamination same BS gasoline engine The quality of presentday automotive Diesel fuels is satisfactory. -4dditive modification of fuel may be useful in reducing fuel-pouring temperature and providing better operation in severe cold.
Future
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Cost and availobility of fuel Demand for increased performance Urge for higher hp./cubic inch of piston displacement Achievement of maximum portability per brake horsepower lowering maintenance costs and increasing engine life between overhauls
tions for the required fuels &s engine production has not gono beyond the experimental stage. Experimental engines are operating on kerosine and leaded gmolines, but the latter should be avoided in order to reduce difficulties associated with lead deposita on turbine blades and heat exchanger surfaces. However, when the gas turbine is initially introduced onto the highways, it will be forced to operate on available fuels-kerosine, Diesel fuels. or leaded gasolines-for economic reasons. Later, if speeid turbine fuels become available, their key fuel points will be burning quality and carbon-forming tendency. Conventional JP-3, -4, or -5 aviation type jet fuels should be ndequate. These fuels could include stocks presently used to prepare low octane fractious, gasoline components, kerosine, and even Diesel fuels. Wide boiling range, low octane number distillate fuels give satisfactory performance in automotive gas turbines if the end point is not high enough to promote carbon deposits. Sulfur content must be low to minimize corrosion and erhmst odor. Additives to reduce corrosion and deposits are a probabilit,?, but present-day additives like tetraethyllead. anti-icing con1pounds, and agents to prevent valvo deposit formation will not find application in turbine fuels.
Free Piston Engine The seriousness of air pollution calls for work on Diesel exhaust smoke. Unburned hydrocarbons, aldehydes, acids, and other cbemids are found in the exhaust, and these rather than the smoke itself may be the key to contamination. Additives and increased volatility are being studied to improve combustion as a lessener of the problem. Today’s Diesel fuels have adequate ignition quality (cetane number) and additives are available to increase this if needed in the future. U. S. railroads are interested in operating an automatic two-fuel Diesel system, wing low cost heavy fuel during heavy duty operations and higher quality fuel for light duty work. Storage stability Diesel fuels is important 8 8 produo$ of degradation (sediment and soluble gums) can cause serious trouhle by plugging filters snd lines snd ultimate starvation of the engine. Soluble gum is deposited on hot surfaces leading to lacquering and sticking of injector plungers. Chemicd additives, added at the refinery or during use, can prevent this formtion. Other additives are used to prevent fuel-water emulsions and to give antirust properties to the fuels.
G a s Turbine The automotive industry has shown much interest in gaB turbine engines, and large scale production by 1960 is expected. These engines do not require high octane fuels, but other fuel problems e x i s t f o r example, it is difficult to draw firm specificaM y 1956
An extremely high theoretical thermal efficiency, rivaling the Diesel, is a high interest point of the free piston engine. Other notable paints include: Very law oost because of simple design No special alloy needed for turbine blades Relatively low level of vibration Satisfactory power-weight ratio Low maintenance Operating flexibility Major problems me mechanicd and are concerned with lubrication of the hot running piston. There appears to be no fuel quality problem not already known to the internal combustion field. Refining Modification
Aside from refining technique changes and the development of new processes, there is a strong possibility that refinery running plans will be altered. More middle distillate fuels for gas turbine and D i e d engines will be produced at the expense of gasoline. Long range planning is essential-production changes take time, and fuU cooperation of the automotive, chemical, and petroleum industries must continue. W. J. Sweeney Esao Research and Engineering Co., 75 West 51st St., New York 79, N. Y.
I N D U S T R I A L AND E N G I N E E R I N G C H E M I S T R Y
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