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INDUSTRIAL AND ENGINEERING CHEMISTRY
temperature coke. Therefore no reliable figures can be made on the cost of producing coke in a particular plant unless it is possible to make fairly accurate assumptions pertaining t o the variables mentioned. Many estimates have been made of the first cost of building a low-temperature coke plant using the Hayes process. The location of the plant, general schematic arrangement, and plant capacity will cause much variation-hence, the general statement: For a plant built t o produce char only in capacities of 400 tons per day or greater, the cost would be about $800 per ton per day feed capacity, and if built to produce low-temperature coke briquets, the cost would be about $1000 per ton per day feed capacity. The amount of by-products fiom the Hayes plant \Till de-
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pend upon the coal being carbonized, but generally the quantity of tars, which is the most important by-product, is considerably higher from the Hayes rctorts than from other low- or high-temperature proceases. To present tangible figures which might apply for different locations and for carbonizing different kinds of coal, Table 1 gives the estimated cost of producing lomtemperature coke by the Hayes process in plants having a capacity for carbonizing 1000 tons of coal per day; these plants are hypothetically located a t Pittsburgh, St. Louis, and Cincinnati. The item of repairs and supplies refers only to the cost of materials entering into the repairs and supplies since the cost of labor for making these repairs is included in the labor cost. Labor and supervision are figured as shown in Table 11.
H. J . R O S E l l e l l o n I n s t i t u t e , P i t t s b u r g h , l’enna.
Anthrarite is a smokeless fuel under all combustion conditions. It does not release even a Lrace of Lar when heated. AnthraciLe i s closely sized, hard enough to resist breakage, and noncaking, and usually has a high ash-softening temperature. Therefore, it provides fuel beds of uniform and dependable character. It is the densest and most concentrated of all solid fuels. For these and other reasons, anthracite permits hand firing with maximum cleanliness and convenience, and is readily used for automatic firing. More than 99 per cent of the country’s anthracite production of 50 million tons annually comes from Pennsylvania, whose reserves are sufficient to last for about 150 years at the present rate of depletion.
NTHRACITE is the only natural fuel which is inherently smokeless under all conditions of use. Liquid and gaseous fuels, as well as coals containing more volatile matter than anthracite, will produce smoke unless they are burned with sufficient air properly mixed with the volatile fuel a t adequate furnace temperatures. Anthracite, however, will not produce smoke in any type of equipment, irrespective of the method of firing, the condition of equipment, or carelessness on the part of users. For a hundred years Pennsylvania anthracite has been the principal smokeless fuel used for heating homes and commercial buildings in the United States. Year after year it has continued to hold first place among the fuels which are burned smokelessly for this purpose. Table I shows its dominant position during the past ten years. According t o available statistics, less than 10 million tons of anthracite are used annually by manufacturing industries, power plants, gas plants, and railway locomotives. After allowing for these uses, it is evident that the amount of anthracite used for heating homes and buildings during the past ten years has been nearly equal to the combined equiva-
A
lent tonnage of all domestic coke, heating oils, and manufactured and natural gas used for domestic and house-heating purposes in the whole United States! X o s t of this anthracite is used in the S o r t h Atlantic states, which explains why that area, in spite of its high population density, has never had a smoke problem comparable to that of many cities elsewhere. The smoke which does occur in the East comes largely from railroads, industries, and heating plants which fail t o obtain smokeless combustion with substitute fuels. Potential Anthracite Production It is fortunate that anthracite pioduction can be greatly increased, becauie the present widespread interest in smoke prevention, stimulated by St. Louis’ successful campaign, comes at a time when unusual demands are being made on fuel production. A recent report from the Office of Production Management t o the President ( 3 ) estimates a shortage of metallurgical coke amounting to 5,360,315 tons during 1941, and states that this should be met by diverting coke from home and commercial uses.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
There is a possibility of inadequate supplies of various other fuels due to their need for national defense activities or t o transportation problems, inadequate production facilities, or lack of man power. However, anthracite production can be readily increased by many millions of tons annually without the necessity of any new capital expenditure and without requiring additional miners. The increased production could be obtained simply by working the mines a greater number of days. During recent years anthracite mines have averaged about 190 working days per year. One million tons would be produced for each additional four days of working time, so that a large increase in production would be possible by using the facilities and man power already available. For fifteen years there has been no strike affecting the whole anthracite industry. An increased demand for anthracite would make possible the saving of many millions of dollars of direct relief and Federal WPA funds which would otherwise be needed in the anthracite region. Anthracite serves a compact marketing area of 40 million persons, and it is used to some extent in a much larger area. Being the densest of all fuels, being resistant to breakage, and not being subject to spontaneous combustion or other fire hazards, it is the ideal fuel for storing or shipping long distances. For example, a ton of anthracite occupies only about half as much space as a ton of coke. This is a vital matter when there is a shortage of transportation and storage facilities such as tend t o occur in times of great industrial activity.
Anthracite Reserves
841
Courtesy, Rudson Coal C o m p a n y
CONECLEANING OPERATION IN THE PREPARATION OF ANTHRACITE The run-of-mine coal enters huge metal cones filled with a mixture of sand and water. This mixture is kept agitated by revolving paddles, and the density is controlled so that the pure coal floats while the impurities sink and are discarded.
This country has large reserves of anthracite. The state geologist of Pennsylvania (2) estimated recently that the anthracite still remaining in that state totals nearly 15 billion tons, or enoughfor about 150 years more a t the recent average rate of depletion. The magnitude of this fuel reserve can be better appreciated from the following comparison. The anthracite reserves of the United States contain as much potential heat energy as all the petroleum produced in the entire world up t o the present time, plus the world’s known reserves of petroleum obtainable by flowing and pumping ( 7 ) .
Classification and Location of Deposits According t o standard specifications, the term “anthracite” is limited to coals having from 2 to 8 per cent volatile matter (92 to 98 per cent fixed carbon) on the dry, mineral-matterfree basis. Coals containing less than 2 per cent volatile TABLEI. AVERAGEANNUALU. S. SALESDURING 1931-40“ Fuel Tonab Anthracite (includin small amount of semianthracite but excluding fuel usecfat collieries for heat and power) 49,800,000 Domestic coke (by-product and beehive) 8,900,000 Heating oils (grades 1-6 inclusive, for heating homes and commercial buildings) 19,500,000 Alftd. gas for domestic and house-heating purposes 4,900,000 Natural gas for domestia and house-heating purposes 13,000,000 a Data are derived from various publications of the U. S. Bureau of Mines and American Gas Association. b Net tons of anthracite or coke, or equivalent tons computed from gross B. t. u. of oil and gas.
matter are “meta-anthracite”, and coals with 8 to 14 per cent volatile matter on the dry, mineral-matter-free basis are “semianthracite”, provided they are nonagglomerating ( I ) , The state of Pennsylvania was endowed with more than 95 per cent of the country’s total reserves of anthracitic coals, and has produced more than 99 per cent of the total United States production of such coals to date. Most of the coal in the anthracite region of northeastern Pennsylvania is true anthracite, including the full range in volatile matter of 2 to 8 per cent. This is the only source of true anthracite in the eastern half of the United States, but semianthracite is produced in Pennsylvania, Virginia, and Arkansas. Anthracitic coals also occur in Colorado, New Mexico, and Washington. Table I1 shows the production of anthracite and semianthracite by states, averaged for three recent years (IO). TABLE11. AVBRAGETOTALANNUALPRODUCTION OF ANTHRACITIC COALS IN THE UNITED STATES, 1936, 1937, 1938 State Pennsylvania Arkansas Virginia Colorado, New .Mexioo, Washington Total
Net Tons/Year 50,844,998 226,251 140,399 37,324
_-
51,254,972
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product or beehive coke. For the same reasons, the fire will remain in good condition longer and under more adverse banking conditions than with coke. C o N c E N T R A T I O N Anthracite provides more convenience and longer intervals between attention than any other solid fuel in hand-fired or magazine-feed equipment. It is so concentrated that a greater weight, and therefore more potential heat, can be charged into the fuel bed or hopper a t each filling. If various fuels are burned a t the same rate, the anthracite will last proportionately longer before the fuel needs to be replenkhed. Anthracite i s noncaking and will burn steadily hour after hour, as contrasted with coals which tend to swell and cake together and which require poking from time to time Courtesy, Hudson Coal C o m p a n y t o obtain full ratinz. A BREAKER WHEREPENKSYLVANIA ANTHRACITEIs PREPARED SMOKELESS ComnsmoN. The relation between the rank of coals and their smokeproducing tendencies was discussed in a Rhode Island and Massachusetts contain a deposit of metaprevious paper, for which reprints are available (8); graphs anthracite or graphitic anthracite, but this material is not showed the amount of smoke and soot observed from suitable as mined for use as domestic fuel and has had limited U. S. Bureau of Mines tests in which coals of various ranks commercial development. were burned in house-heating boilers. The same paper also showed the relation between rank of coal and the yield of lowChemical and Physical Properties temperature tar (Figure I), which is one of the principal factors in smoke production. True anthracite does not yield An extensive discussion of the chemical and physical propeven a trace of tar when heated; in fact this has been proerties of anthracite will not be presented here, since this subposed as a test to distinguish between anthracite and semianject has been covered by previous papers, for which reprints thracite in border-line cases (9). Neither anthracite nor are available (6, 7 ) . Only a few of the most important points semianthracite produced smoke or soot in the U. S.Bureau from the standpoint of househeating will be summarized beof Mines tests in house-heating boilers, but smoke and soot low. appeared when ooaIs of about 18 per cent or more volatile HEATING VALUEAND AN,u,YsIs. I n 1935 the u. 8. Bureau matter were burned. of Mines sampled the production a t forty-one breakers in all parts of the anthracite region of Pennsylvania, representing about 50 per cent of the industry's total production ( 2 1 ) . HIGH-VOLATILE A MEDIUM-VOLATIL LO'#-VOLATILE SEMIBITUMINOUS BITUMINOUS l e N T H R 4 C l T E 1 4 N T H R A C ' T E ~ ~ ~ ~ BITUMINOUS The heating value of the egg, stove, and chestnut sizes 400La / ~ ' ' ~ ~ ~ ~ ~ ~ l ' J ' I l ~ ~ ~ ~ I ' ~ ranged from 13,550 to 13,670 B. t. u. per pound, dry basis, and the ash content of these sizes ranged from 9.2 to 9.7 per 3 0 0 ~ ~ cent. The ash-softening temperatures averaged about 2900" F. The sulfur content was very low, averaging only ZOOLB 0.7 per cent in all sizes. This is an important advantage from the standpoint of air pollution. Anthracite has from 500 to 800 more B. t. u. per pound than IOOLB by-product or beehive coke of the same moisture and ash content (11 ) . 0 ADVANTAGES FOR STORAGE. Anthracite has a specific % DRY V O L A T I L E M A T T E R , MINERAL-MATTER-FREE BASIS gravity ranging from 1.47 t o 1.66, and requires less space for storage than any other solid fuel. It does not deteriorate durFIGURE 1. REEATTON BETWEEN RANKOF COALAND YIELDOF ing storage and is not subject to spontaneous combustion. ~OW-TEMPER4TURE T A R ]\'HEX HEATED It does not present any fire or explosAonhazard from leakage, (Pounds of tar per ton of moist, mineral-matter-free ooal) and a whole year's supply may be stored on the premises with safety. SIZEAND PREPARATION STAKDARDS. Pennsylvania anthraGROSS AND NET HEATING VALUElis. EFFICIENCY. Fuels cite is available in eight standard sizes, which are carefully are often compared on the basis of their "gross" heating value prepared in accordance with published specifications. This -that is, on the assumption that use will be made of the makes it possible to select the size which will give the best latent heat of condensation of the water vapor produced by possible results in each piece of heating equipment. No other the combustion of hydrogen. Xn actual practice, the latent solid fuel is prepared to uniform specifications controlling the heat in the water vapor passing up the chimney is mostly Post, size and quality of products for the whole industry. so that the "net" heating value is the logical figure to use. BBRNIXG CHARACTERISTICS. Anthracite is available in at The loss in efficiency due to this cause is about as follows, expressed as the difference between gross and net heating least three types-hard, medium, and free burning. They vary in hardness, volatile matter, and temperature of ignition, values : so that individual preferences or special needs may be met. Gas 10% Heating oil 6-7 Because of the medium ignition temperature and volatileBituminous coal 3-4 matter content of anthracite, it is easier to ignite than byAnthracite 2 a
u
1
LB
1
I
'
I
~
July, 1941
INDUSTRIAL A N D ENGINEERING CHEMISTRY
a49
Room Thermostor
HEATWITH ANTHRACITE F I G U2.~ AUTOMATIC
When an amount of domestic fuel oil equivalent in net heating value to a ton of anthracite is burned, it will produce about 200 gallons of water; an equivalent amount of natural or manufactured gas will produce about 300 gallons. An outside chimney in cold weather is likely t o condense some of this water; the condensation is promoted by the presence of sulfur oxides which dissolve in the water to form an acid solution that attacks the mortar and leads to seepage, with resultant damage and unsightly appearance. A drain connecting the base of the chimney t o a sewer may be necessary. Anthracite contains enough hydrogen to give good ignition and burning properties as compared with high-temperature coke, but not enough to cause trouble from chimney condensation.
Uses MAGAZINE HEATERS.Since anthracite is a concentrated, noncaking fuel, i t is ideally suited for use in magazine heaters of various types. I n general, anthracite will give clean, controlled heat for 24 hours or longer, with little or no attention. Several excellent types of magazine-feed equipment are available, and more use should be made of this principle of firing, especially for moderate-cost installations. AUTOMATIC HEAT. The physical characteristics enumerated combine to make anthracite the most readily adapted of all solid fuels to completely automatic operation. Anthracite stokers which withdraw fuel from the bin and deposit ashes in cans or storage pit are available in many approved makes, and are extensively used throughout the East. I have personally fired almost every well-known type of fuel, ranging from western lignite, subbituminous coal, and
Arkansas semianthracite to eastern bituminous coal, coke, gas, and anthracite. I am now burning rice anthracite automatically in my home in Pittsburgh, since it costs no more delivered in the bin than lump sizes of smokeless fuels produced in western Pennsylvania for hand firing. The anthracite is stored in a neat bin constructed of fir plywood, and the stoker automatically withdraws and burns coal in accordance with the demands of a thermostat in the living quarters (Figure 2). The ashes automatically spill by gravity over the edge of the retort into a tight storage pit beneath the floor level. Two or three times a year the ashes are removed, after dampening to avoid dust, and used to improve the heavy clay soil of the lawn and garden. (This use is based on an investigation made a t Mellon Institute, 6.) The stoker installation operates for weeks at a time without attention of any kind, with excellent heating results. No change in cleanliness has been noted as compared with the gas heat previously used. Complete working drawings with estimates of materials and labor required have been prepared at Mellon Institute for gravity ash-removal methods and modern anthracite bins. These apply to both hand-fired and automatic anthracite installations (4). INDUSTRIAL USES.Small sizes of anthracite are burned on stationary and traveling grates and in powdered coal burners for power generation. They are also used to some extent mixed with bituminous coal in underfeed stokers, locomotives, etc., to reduce smoke, to give better fuel-bed conditions, and to lower costs. Anthracite is also used in the manufacture of water gas and producer gas and to some extent for various metallurgical uses.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Conclusions Anthmcite is the principal smokeless fuel. During the past ten years the quantity of anthracite used for heating homes and commercial buildings approximately equaled, in net heating value, the combined sales in the United States of domestic coke, light and heavy heating oils, and natural and manufactured gas used for domestic and house-heating purposes. Anthracite is the only natural fuel which is smokeless under all conditions of use. It is the most concentrated, strongest, and cleanest of all solid fuels, and is available in a wide range of st’andard sizes. It can be ignited readily, burned a t the desired rating Tyith little attention, and banked for long periods. It is safe to store in any quantity. Since anthracite is closely sized, noncaking, and nonclinkering under normal conditions of household use, ideal fuel-bed conditions can be readily maintained, and it is equally well adapted to automatic (stoker) firing, magazine feed, or hand firing. This combination of properties explains why anthracite has long been the standard domestic fuel with which other fuels are compared. Yearly all of the true anthracite ( 2 to 8 per cent volatile matter) produced in the United States is mined in northeastern Penneylvania. It is used principally in the Xorth Atlantic states, which explains why that densely populated sect’ion has never had a smoke problem comparable with .many cities in other sections of the country. The present
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average production is about 50 million tons annually, which could be promptly increased by many millions of tons, even under present emergency conditions. This could be done without the need for additional capital investment simply by working the collieries a greater number of days per month. Semianthracite (8 to 14 per cent volatile matter) is produced to the extent of a few hundred thousand tons per year in Pennsylvania, Virginia, and Arkansas. Small amounts of anthracitic coals are also mined in Colorado, Tew Mexico, Washington.
Literature Cited Am. SOC. Testing Materials, Standard Specifications for Classification of Coals by R a n k , Designation D-3S8-38 (1938). Ashley, G. H., Trans. 1st Ann. Anthracite Conf. Lehigh Unia., 1938, 11-24. Duim, Gano, Steel, 108, No. 9, 21-2 (1941). Mellon I n s t . , Bd2. MA-1, M-2 (1938), and M-3 (1939). Mellon Inst., “How t o Imyrove Your Lawn and Garden w i t h Pennsylvania Anthracite Ash”, 1939. Rose, H. J., T r a n s . 1st Ann. Anthracite COILE. L e h i y h Urkh, 1938, 25-38.
Ibid., 2nd Conf., 1939, 27-44. Rose, H. J., and Laaseter, F.P., Trans. Am. SOC.Heating Vent i l a t h g Engrs., 45, 329-38 (1939) : Heating, P i p i n g , A i r Conditioning. 11, 119-22 (1939). Turner, H. G., T r a n s . Am. Inst. M i n i n g Met. Engrs., 108, 33043 (1934). U. S. Bur. Mines, Mineral Yearbook. 1938, 1939, 1940. U. S.Bur. Mines, Repl. Investigation 3283 (1935). COITRIBGTION from the Anthracite Industries Fellowship, Mellon Infitiruti.
M.D. CURRAN Coal Carbonizing Company, S t . Louis, $10.
T
HIS process v a s developed primarily for producing smokeless fuel from feebly coking Illinois coals to provide St. Louis with a means by which it could eliminate the smoke nuisance. Previous efforts, in which many millions of dollars were employed, met with failure because the coke produced could not be burned satisfactorily in existing stoves and furnaces, and the cost was so high that i t could not
compete with the cheap low-grade coal. From a technical viewpoint it was necesfary to produce a coke substance which would be sufficiently reactive to give full heat a t fuel bed temperatures below the fusion temperature of the ash, and from a n economic viewpoint the manufacturing cost must be such that the fuel consumers in St. Louis could get their heat at substantially the same annual cost.
