Jan., 1921
T H E JOL;RATAL OF I i V D C S T R I A L d i T D E X G I -V E E R I G CH E M I S TR Y
must be distinguished here. I believe t h a t they can be made just as stable as needed. Samples prepared in t h e laboratory have lasted 1 2 t o 18 mo. in quite stable form (Fig. 12). An fmportant point here is t h a t reagitation, before sedimenting has progressed too far, will give a further extension of life. The grade of fuel can be fitted t o t h e conditions of permanence and stability required, and is technologically related to t h e dispersity gradient, t h e varying properties of particles of different dimensions in it. Colloidal fuel is a composite dispersoid, t h e particles of which range from solution through t h e colloid t o suspensions. With every advance in t h e technique of t h e subject, t h e right proportioning and grading of those for a given purpose becomes better understood, and t h e relation of t h e dispersity gradient t o stability and use becomes clearer. F U E L CONSERVATION, P R E S E N T AND F U T U R E By Horace C. Porter 1833 CHESTNUT STREET, PHILADELPHIA, PA.
Progress in t h e application of fuel t o t h e needs of mankind is being manifested in an improvement of methods, a rise in t h e curve of efficiency, as well as in t h a t of total consumption. To-day, resulting from increased use of scientific methods, we see greater returns per t o n of coal t h a n I O yrs. ago. The per capita consumption of fuel i n t h e United States has increased b y only 7.5 per cent in t h e last I O yrs.-from 152.3 to 163.9 millions of B. t. u. T h e increase has been i n oil and gas, not coal. It is cause for congratulation, therefore, t h a t notwithstanding greater industrialization, higher standards of living, and t h e devoting of vastly increased industrial yields t o t h e benefit of other nations and of ourselves, we have maintained so small a n increase in fuel consumption. Fuel production is with difficulty, however, keeping up t o t h e demand. Under t h e trying conditions'of t h e last few years, transportation deficiency has retarded fuel distribution and production, so t h a t a real shortage exists to-day. T h e loss of 50,000,000 tons from t h e normal coal production during t h e nation-wide coal strike o i 1919 p u t industry in t h e position of holding back needed improvements and new construction which now are calling urgently for more fuel. Stocks also need t o be built up. Exports from tidewater have leaped t o 600 per cent in 2 yrs , and threaten tQ pass 2 5 , 0 0 0 , 0 0 0 tons for this year. I n t h e face of these facts, and of t h e impression prevailing in many quarters of a dwindling coal production, i t is i n a measure reassuring t o ' n o t e t h a t for t h e first 6 mo. of this year coal production is 19 per cent greater t h a n i n t h e corresponding period of last year, and oil is 1 5 per cent greater. As compared similarly t o 1917 and 1918, war years, coal has this year fallen behind by 5 and I O per cent, respectively. Reconstruction now urges upon us t h e use of additional fuel. T o emerge from t h e transition period of 1919 and make this truly a reconstruction year, our industries must be given t h e necessary coal and oil. AS t o how far we fall short now of our proper
47
share in t h e world's reconstruction, t h e economists can perhaps make better guesses than chemists and engineers. But in point of coal consumption we may make comparison with 1918 when expanded war industries brought this item t o t h e highest point it has ever reached i n this country, before or since, and find t h a t our present rate is b u t I O per cent in arrears, of which probably half can be accounted for b y increase in exports. Professionally, t o t h e industrial chemist and engineer, conservation appeals as a n important aid i n removing or reducing fuel shortage. A reasonable and practicable increase in fuel economy would help materially in bringing supply and demand closer together. There would be exerted in consequence of i t , also, an influence toward lowering of prices. Notable advance has been made during recent years, b u t t h e practical maximum of efficiency has b y no means been reached. There is not t o be overlooked or minimized t h e tendency of human nature t o use available natural resources t o t h e limit, with little regard for posterity. Yet in times of shortage i n supply, t h e consumer perhaps has his interest more easily aroused i n means of cutting down requirements and reducing raw material costs. Bituminous Coal Used (Net Tons) 1917 130,lSO.OOO
Per cent of Total Consumption 23.4
90,000,000
16.2
(3)IBEEHIvE C O K I N G . . . . . . . . . . . . . . . . . . . . 52,250,000 ( a ) Gradual abandonment in favor of by-product coking ( b ) Utilization of waste heat in boiler firing (4) BY-PRODUCT COKING. . . . . . . . . . . . . . . 31,500,000 ( a ) Increased utilization OF waste heat through regeneration, recuperation and steam generation: increase in' surplus gas and its utilization ( 5 ) RAILROADS.. ........................ 156,150,000 ( a ) Use of feed-water heaters and economizers on locomotives ( b ) Economy of steam pressure by idle locomotives (6) DOMESTIC.. ......................... 57,100,000 (5) Avoidance of unnecessary heat in unused places and of excessive temperature when not needed j b ) Economy of gas used as fuel by adjustment of appliances 39,700,000 (7) O T H E R U S E S . . ...................... (Gas manufacture, export, and bunkering of vessels) 556,8SO,OOO TOTAL. .........................
9.4
MEANSO F C O N S E R V A T I O N ( I ) INDUSTRIAL POWER.. ............... (excl. steel mills and coking) ( a ) Increased use of economizers, superheaters, feed-mater heaters, mechanical stoking ( b ) Care in firing, with control of flue-gas composition and temperature (c) Use of gas engines in conjunction with steam, on power plants where load is variable (2) STEELAND IRON INDUSTRY.. . . . . . . . . . (excl. coking) ( a ) Increased use of gas for heating and Dower. and of regeneration and POSSIBLE
5.7
28.0
10.2
7.1 100.0
Many of t h e expedients for raising t h e efficiency of fuel utilization are of such a nature as t o require large changes of existing plant and equipment-the centralization of power development, for example, in super-power stations, t h e electrification of railroads, ai-td t h e building of by-product recovery coke plants. These changes go slowly, and depend greatly on general financial conditions and t h e prevailing cost of capital
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outlay. Other expedients afford in the meantime quicker realization of efficiency gains, not as large, b u t of distinct importance in practical conservation. T h e preceding tabulation of the country’s coal consumption in 1917,b y classes of users, is taken from t h e U. S. Geological Survey reports, and is coupled with an outline of some of the means whereby conservation might be accomplished in t h e different fields without great delay. PRESENT CONDITIONS
It is t o be noted t h a t seven-tenths of all t h e coal is burned under industrial and locomotive boilers and in metallurgical heating furnaces. It is in this large field t h a t perhaps t h e most immediate opportunity for improved efficiency exists. BOILER FURNACE EmIcmNcY-In boiler furnace economy roughly half of t h e efficiency losses a r e due t o heat carried away in the chimney gases; under commonly prevailing conditions a n increase of I in t h e percentage of COZ in t h e chimney gases means a lowering of t h e excess air by about I O per cent, a consequent reduction in t h e B. t. u.’s carried away in sensible heat, and a gain of 1.5 t o 2 per cent in t h e combined efficiency; a lowering of the flue-gas temperature by 100’ F. means an additional gain of over 3 per cent in boiler a n d furnace efficiency. It is somewhat startling t o those who have not stopped t o consider the matter carefully, t o find t h a t for every pound of coal burned, I j t o 25 lbs. of chimney gases result, carrying out their sensible heat t o waste. These efficiency gains are not in large figures, b u t they mean a good deal when applied t o t h e large tonnage of boiler fuel used. Superheaters and feed-water heaters, if more generally applied, would add further t o t h e saving. D. D. Pendletonl has recently estimated t h a t only 1 5 per cent of t h e steam raising capacity of t h e country is equipped with superheat, and t h a t t h e remainder not so equipped would gain between 14 a n d 2 0 per cent in efficiency by its use. R A I L W A Y L O C O X O T I V E OPERATION-In railway IOCOmotive operation it is t r u e t h a t considerations other t h a n those of thermal efficiency are highly important in obtaining the driving capacity required. On t h e other hand, there are some opportunities for fuel saving here, and i t is a big field in point of total consumption. I n a n article on “Locomotive Feed Water Heating,”2 T. C. McBride has recently claimed t h a t devices for this purpose, utilizing t h e exhaust steam, save on locomotives I O t o 13 per cent of t h e coal used, as compared t o injector operation. T h e maintaining of high steam pressure unnecessarily in locomotives standing idle in yards, t h e preventable part of t h e so-called stand-by losses, is no doubt a factor in t h e large railway consumption of coal. INDUSTRIAL HEATING FURNACES--A great deal of coal is used in industrial heating furnaces for t h e heat treatment and reworking of metals, the rolling a n d forging of steel, and for tempering processes. 1 2
Blast Furnace and Steel Plant, 8 (1920), 350. Mech. Eng., 42 11920), 281.
Vol. 13, No.
I
Prof. H. M. Thornton’ has recently brought out t h e great advantages and economy of gas as a fuel for these furnaces. Records are presented showing comparative results in various sizes and types of furnaces from the small rivet heaters t o t h e large forging furnaces, t h e saving in fuel cost as compared t o direct coal, coke, and oil firing ranging from 40 t o 6 0 per cent. Indirect advantages also result in increased capacity per unit a n d decreased labor cost. Prof. W. Trinksj2 of Pittsburgh, shows these economies in t h e use of gas a n d of powdered coal in a series of articles on heating furnaces. The latter is pessimistic as t o t h e practicability of such savings, owing t o the human tendency of firemen t o waste fuel when they can do so easily by t h e turning of a valve. It would seem, however, t h a t under t h e inducements of a bonus system this same ease of turning a valve might prove a factor leading t o conservation. An actual record is given by A. A. Cole3of a powdered coal installation in a large heating furnace used in t h e manufacture of rolled steel wheels, wherein an economy of 30 t o 40 per cent over direct hand firing was obtained, and a labor saving equal t o 1 5 per cent of t h e fuel cost. A t steel plants where by-product oven tar-an excellent fuel for t h e open-hearth furnace-is available, greater value frequently can be obtained from t h e t a r as fuel based on comparative coal cost a t t h e plant, than is obtainable in t h e open t a r market. Changes in open-hearth- and heating furnace construction designed t o regulate combustion and length of flame are proving in actual plant trials t o effect a n increase in metal output, reduce waste heat losses, a n d raise fuel economy by I O per cent, without i m pairing t h e life of t h e furnace. WASTE HEAT BoILERs-More attention t o waste heat losses on industrial furnaces and in t h e older by-product coke plants, with increased use, or more efficient use of regeneration and recuperation would pay well in fuel saved, giving added surplus gas a t t h e coke plants. Waste heat boilers are used on many industrial gas-fired furnaces and by-product coke plants. Their application could be widely extended with profit and a n important degree of fuel economy. Brick and pottery kilns, copper a n d zinc a n d cement furnaces, and beehive coke ovens, show waste gas temperatures from 1200’ t o 2000’ F. A large steel plant near Pittsburgh operates waste heat boilers on the outlet flues of its rectangular nonrecovery coke ovens, obtaining thereby a steam o u t p u t which has reached 2 7 h. p. per oven. Reduced t o t h e basis of coal-burned, this figure becomes in h. p.-hrs. per pound of coal more t h a n 2 j per cent of the average yield from complete combustion in steam plants. MIscELLANEous-Large gas-engine-driven power stations are being used by steel works on blastfurnace gas with conspicuous success a n d large fuel economy, as a t Gary, Ind., by t h e U. S. Steel Corporation, and a t Sparrows Point, Md., by t h e Bethlehem Steel Corporation. Such means of power production 1
a
J . R o y Soc. Arts, 68 (1920), 346. Blast Furnace and Steel Plant, 8 (1920),327
8 l h i d . 8 ( 1 9 2 0 ) , 417.
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1921
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can be extended, and a saving effected in coal more t h a n equivalent on a B. t. u. basis t o t h e gas used, owing t o t h e comparatively high efficiency of the gas engine. Anthracite coal is being reclaimed from t h e river bottoms in eastern Pennsylvania, and from the culm banks by washing and briquetting. Culm also, experimentally, has been mixed with pitch or bituminous coal and carbonized. I n the domestic fuel field, comprising I O per cent of t h e bituminous consumption (or 1 7 per cent based on both anthracite and bituminous), t h e greatest economies will eventually come from increased use of gas a n d carbonized fuels. The domestic field will be one of comparatively low efficiencies, however, as long as small-sized fuel burning units remain. Economies can be made by using care as t o overheating of houses, particularly of unused portions of houses. Furthermore, in t h e burning of gas in domestic appliances i t has been shown b y recent experiments at Ohio State University‘ t h a t efficiency of utilization of t h e heat may vary from 16 t o 40 per cent, according t o t h e distances of t h e burner from the vessel heated. F U T U R E POSSIBILITIES
For t h e future, with t h e steady a n d permanent growth of fuel economy through gradual adoption of major improvements requiring time and large capital outlay, there is reasonable prospect t h a t t h e per capita fuel consumption in this country may reach its peak a n d begin t o decrease, as in fact already t h e coalconsumption curve, per capita, appears t o have reached almost its high level. E L E C T R I F I C A T I O N O F RAILROADS-The most striking possibility among these major improvements looking t o fuel conservation is t h e electrification of railroads. It has been carefully figured b y A. H. Armstrong, of the General Electric Company, for t h e Committee . on Electrification of Steam Railroads, National Electric Light Association,2 t h a t by universal electrification of steam railroads in this country a direct saving of 1 2 2 , 5 0 0 , 0 0 0 tons of coal per annum, two-thirds of t h e present railway fuel consumption, would result. This leaves water power out of account and compares on t h e basis of steam generated electric power in central stations. Deduction is made from t h e present steam engine ton-mile movement for company coal haulage a n cars and tenders. The Chicago, Milwaukee and St. Paul Railway has had in successful operation for over 4 yrs. large electrified portions of its system in Montana and Washington. The electrification now totals 645 route miles. Power is purchased from t h e Montana Power Company. I n a detailed statement of actual operating costs made t o t h e National Electric Light Association, R . Beeuwkes, of t h e Milwaukee and St. Paul Company, compares steam operated and electrically operated divisions in respect t o those items of expense affected b y t h e t y p e of motive power used. For t h e totals of these items electrical operation shows about 40 per cent lower cost, and on t h e one item of train loco1
MccR. Eng., 42 (1920), 287.
* See Reports of this Committee, 1920.
49
motive power cost as against locomotive fuel used, t h e saving amounts t o 53 per cent, not taking into account t h e cost of fuel haul. These are direct savings, exclusive of the manifest indirect advantages accruing from t h e release of freight cars by gain in speed of haulage, t h e release t o revenuebearing traffic of coal cars now hauling railway coal, t h e avoidance of boiler feed-water expense, t h e improvement in reliability and safety of railway service, and t h e increase of property valuation around railway terminals. Most of these items will aid in decreasing t h e menace of fuel shortage in t h e future. High cost of installation, and t h e present difficulties in t h e way of financing railway betterments, will act t o retard this great step in t h e progress of fuel conservation. The passage of t h e recent water power legislation by Congress should, however, exert a large influence in furthering such projects. Water power development under favorable government regulation not only affords low cost power, b u t releases coal car equipment in greater measure t h a n would central steam stations. President A. H. Smith, of t h e New York Central lines, has stated: It is known that, generally speaking, hhe operating cost (exclusive of fixed charges) of electric service is less than it would be for a similar steam service;. . . . . .the further extension of electric operation on steam railroads depends to a considerable extent upon the cost of electric power;. . . . . .There is a point where the cost of coal will cause the price at which electric power is available to the railroad t o result in sufficient saving. . . . . .to warrant the expenditure for electrification. CENTRALIZATION O F P O W E R SYSTEhfS-The central super-power” station for general power service, gradually displacing less efficient scattered units, will effect large saving of power-plant fuel. The war aroused all nations t o a realization of t h e importance of reliable and adequate industrial power, efficiently produced, for maintaining industry and national effectiveness a t the maximum. The British Fuel Research Board and t h e Nitrogen Products Committee have made, and are continuing, comprehensive studies of power development centralization. Our own Congress has just provided $125,000 for investigation of a possible super-power project for t h e Boston-Washington district. There are installed now in t h e United States, or nearing completion, central power stations aggregating about 350,000-kw. capacity which use coal at or near t h e mine mouth. These stations are laid out for an ultimate capacity a t least double t h a t of t h e present installation. They are consuming coal at an average rate not far from 2.0 lbs. per kw.-hr. on t h e switchboard, one-third less t h a n t h e average consumption of public utility power plants throughout t h e country, as shown b y statistical reports of t h e U. S. Geological Survey. The advantages gained from t h e saving of freight on coal and in reliability of service, add their weight t o those resulting from increased fuel economy, as Reduction of overhead ‘ shown by t h e above figures. and labor cost, and, of t h e capital charges per unit of power output unquestionably follows centralization into large operating units, t h e gain being emphasized (I
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T H E J O U R N A L OF IIVDLrSTRIAL A N D ENGILVEERING C H E M I S T R Y
by 60 choosing conditions as t o permit of operation under a high load factor. For this reason a superpower station project may well take into account t h e disposal of its output in part t o chemical and electrochemical industries which can use power a t night or during t h e ‘(off-peak” periods. By-product recovery in connection with centralized power development commends itself , on grounds of conservation, t o most careful investigation. Direct coal-fired steam-turbo-electric stations afford a high degree of fuel economy, but they waste entirely a valuable national resource in t h e nitrogen of t h e coal, 1 t o agriculture and t o munitions of war. T h e Nitrogen Products Committee of the British Ministry of Munitions, after thorough investigation of various systems of power production from coal, came t o the conclusion t h a t t h e net cost of power in processes involving carbonization or gasification of coal and burning of the resulting coke and gas under boilers was higher t h a n in direct coal-fired steam turbine stations, allowing a fair market value t o t h e byproducts. Both high- and low-temperature carbonization were considered. The possibility of using gas engines for power was dismissed by the Committee as entirely impracticable for stations of t h e size necessary for competitive operation under British conditions. The reason advanced was t h e very high capital cost of such installations a n d the cost for labor and repairs. These conclusions do not necessarily apply t o the American problem of centralizing power development for miscellaneous demand under a more widely varying load. Gas engine power plants of 50,ooo-kw. capacity on blast-€urnace gas, in units of 2 0 0 0 t o 5000 kw., are operating successfully in this country a t costs for labor and repairs not materially higher t h a n those for equivalent steam turbine plants. It appears t h a t with due consideration of the returns from sale of byproducts and with due care so t o restrict t h e scale of operation as not t o overload t h e by-product market, a combination may be found practicable wherein gas power would be used t o meet t h e steady portion of t h e plant load and coal-and-gas fired boilers t o meet the variable load. Surplus gas may be sold t o t h e gas companies for mixing with their own manufactured outputs, or for reinforcing t h e waning supply of natural gas. The problem of choosing the best system for production of gas and by-products in such central stations is a many-sided one. T o go into a detailed consideration of it here would take us too far afield. A very important phase requiring investigation is the mechanical problem of proper design of engine t o use gases of high hydrogen content. This may or may not have been sufficiently worked out at t h e present time. The gas-making process t o be used in such a n installation would be one permitting economical recovery and high yield of ammonia, and a t t h e same time affording the highest thermal return from the coal. Certain processes for the complete gasification of coal b y alternate production, in t h e same generator, of distillation gases and of water gas by superheated steam, have been developed t o some extent and I
Vol. 13, N o .
I
show indications of being capable of higher thermal efficiency than t h e two-stage gasification processes now prevailing in coal-gas and water-gas manufacture. Such a mixed gas would have a heating value of about 320 t o 350 B. t. u. per cu. f t . , a ton of coal yielding about 50,000 cu. f t . if completely gasified. Ammonia would be obtained in higher yield per ton t h a n from present carbonization processes. Other valuable byproducts would be recovered. The possible use of oxygen produced electrolytically from off -peak power on the plant t o enrich t h e blast in such gas generators is worthy of investigation for t h e sake of lowering t h e content of nitrogen and hydrogen in t h e gas. It may be found practicable in t h e future also, when low-temperature carbonizing processes have been further developed, t o make use of them in such a central station t o a limited extent, possibly for raising t h e heating value of t h e mixed gas and for producing a clean, smokeless, solid fuel for disposal t o t h e donestic and small steam trade. Central power stations, distributing electric power only, are not likely t o displace steam plants for heating purposes, or for chemical manufacture, dyeing, bleaching, etc. It is desirable, however, in the interests of conservation t h a t carbonized fuels and gas be increasingly used for this purpose. G A S MANUFACTURE-The trend in public gas supply is toward t h e abolishing of lighting standards and t h e substitution therefor of a thermal requirement lower t h a n has prevailed in t h e past. New Jersey has recently adopted a 5 2 5 B. t. u. standard; t h e city of Philadelphia has just agreed t o a 530 standard; Massachusetts has 5 2 8 , and many other sections of the country, including Chicago, are similarly progressive. This means a lowering of t h e previous requirements by 7 5 or I O O B. t. u., and will result in immense savings of oil in water-gas manufacture. It will permit also t h e use of by-product coke-oven gas unenriched, and in coal-gas manufacture t h e steaming of retorts t o give greater yields of both gas and by-products, t h e increased gas yield permitting still more conservation of oil in water gas. The cracking of oil in water-gas manufacture is a wasteful process at best, yielding soot and t a r in place of available heat units, and having lower thermal efficiency t h a n t h e direct burning of oil as fuel. If gas companies were t o be permitted still further reduction of heating value, together with suitable adjustment of rates t o accord with t h e lower costs of manufacture, there would undoubtedly result an extension oi t h e use of gas, particularly in t h e industries, with its attendant economies mentioned earlier in this paper. By-product coke ovens are steadily increasing in number, but nearly half of the coke is still being made by the old nonrecovery process, which burns, in effecting the coking operation, I O per cent of the coal and all of the gas and by-products. If t h e 24,000,000 tons of coke now made annually in beehive ovens were t o be made in modern recovery ovens, it is safe t o say t h a t a reduction of 8,000,000 t o I O , O O O , O O O tons in coal consumption would result, this being an
Jan.,
1921
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
aggregate of t h e fuel equivalent of gas and t a r saved, increased coke yield, and improvement in blast-furnace fuel efficiency. Ammonia and benzene recovery would be an additional gain. The conservation of coal by means of coking will grow as t h e outlet for coke and by-products grows. Extension in this field is not t o be considered as limited b y t h e metallurgical demand for coke. Coke and coke-oven gas as fuels, however, are likely t o meet strong competition eventually from cheap power developed in central stations and from lower-cost gas made b y complete gasification processes. C O T ~ L O I D A L FuEL-colloida1 fuel deserves mention in connection with fuel conservation. Colloidal suspensions of pulverized coal in oil permit of t h e same economies in application as either oil or powdered coal alone, and have some advantages, notably permitting t h e use of higher ash coals, higher sulfur oils, and many carbonaceous waste products, concentration of heating value in relation t o bulk, and decreasing of fire hazard as compared t o oil. It is of important bearing, however, on t h e probable future development of this new fuel t o consider t h e oil reserves available t o t h c United States for fuel purposes. SUMMARY
I n general, why is fuel conservation t o be needed when our transportation systems shall become equipped t o deliver what is required? I n t h e first place, efficiency in t h e use of raw materials makes for increased financial returns ; secondly, waste promotes extravagance and raises t h e cost of living; and lastly, our high-grade fuel reserves are being exhausted a t a n alarming rate. George H. Ashley, S t a t e Geologist of Pennsylvania, estimates' t h a t practically all of t h e easily workable coal beds of Pennsylvania, 6 f t . or more in thickness, will disappear in 7 5 t o 80 yrs. at t h e Low sulfur present rate of increase in exhaustion. coals for metallurgical purposes are becoming scarce, so much so t h a t steel men are investigating measures for gctting along without them. Yet t h e low sulfur Pocahontas and New River coals are still sold i n large part for steaming purposes, where such low sulfur content is not a n essential quality. There is a progressive tendency, however, in America towards greater fuel economy, and future developments are likely t o decrease materially our per capita consumption. DISCUSSION
DR. PORTER:It will perhaps bear repetition €or the sake of
emphasis, that statistics show we are progressing remarkably well in economic utilization of coal, and this paper accordingly is not l o be taken as a criticism of progress or lack of progress. The consumption of coal per capita in the country has not increased in the last few years, in spite of the fact that our iron and steel production has gone up 50 per cent in I O yrs., and industrialization in general has very greatly expanded-the production of automobiles, for instance, has multiplied itself nearly ten times; also the standard of living to-day is much higher in all classes than it was I O yrs. ago, and yet the consumption of coal per capita has remained practically on a level. Undoubtedly, therefore, we have made very material progress in the efficiency of our application of coal. 1
By private communication supplementing published reports.
DR. T. E. LAYNG:Mr. Chairman, I would like t o ask Dr. Porter about that 7.I per cent of coal used for gas making, export, and bunkering. The exporting of coal has been severely criticized; a great many people think it ought t o be used in this country. I should like t o know about what percentage of t h a t 7 . 1 per cent is exported. DR. PORTER: My recollection of the figure for export this year is that it is running now over z,ooo,030 tons per month, from tidewater, and a little less exported t o Canada, which will at that rate bring the total for this year close to 40,000,000 or 45,000,ooo tons. The figures in the paper are for 191j . The export figures this year are very much higher than in 1917. The export in 191j , as I remember, was about 23,000,000 toas, or 4.3 per cent of the total coal. Gas making required only about 5,000,000 tons, or I per cent, and bunkering the balance
GASOLINE LOSSES DUE TO INCOMPLETE COMBUSTION IN MOTOR VEHICLES1 By A. C. Fieldner, A. A. Straub and G. W. Jones PITTSBURGH EXPERIMENT STATION, U. S. BURBAUOB MINES, PITTSBURGH, PA.
The rapidly increasing use of motor vehicles in t h e United States has introduced an entirely new problem i n t h e proper ventilation of tunnels, subways, and other confined spaces through which such machines must pass. This problem was brought t o t h e a t t e n tion of t h e Bureau of Mines last November by t h e New York and New Jersey State Bridge and Tunnel Commissions with reference t o t h e ventilation of the proposed vehicular tunnel under t h e Hudson River. This tunnel, consisting of twin tubes 29 ft. in diameter and S j o o f t . long between entrance and exit (Fig. I ) , presented an unprecedented problem in ventilation both on account of its length and on account of the traffic density, which is expected t o reach a maximum of 1900 vehicles per hour. An exhaustive s t u d y b y t h e tunnel engineers of all available d a t a on t h e amount and composition of automobile exhaust gas disclosed very little information on t h e percentage of carbon monoxide in motor exhaust gas from t h e average run of automobiles and trucks under actual operating conditions on t h e road. It was well known t h a t carburetor adjustment and other operating factors changed t h e percentage of t h e poisonous constituent, carbon monoxide, from practically o t o 1 2 or 13 per cent; b u t no safe estimate could be made of t h e most probable figure without further investigation. A series of tests was therefore undertaken in which passenger cars and trucks were tested in exactly t h e same condition as furnished b y t h e owners from whom they were borrowed. No change WAS made in carburetor adjustment or any other operating condition, t h e prime object being t o obtain information on existing operating conditions and not t h e ideal conditions of careful adjustment under which t h e usual test of t h e automotive engineer is made. For this reason t h e d a t a are of especial value i n showing t h e proportion of gasoline wasted b y t h e average automobile owner and truck operator through imperfect combustion. 1 Published with the permission of the Director, U. S. Burealo of Mines and of the Chief Engineer of the N e w York and New Jersey State Bridg and Tunnel Commissions.
