The making and assembling of chemical analyses and calorific
determinations (checked by other tests) of carefully selected samples of
coals from nearly 1,000 different localities, in the different coal
fields of the United States, with the additions, from time to time, of
samples representing parts of coal fields or newly opened beds of coal
in the same field, furnish invaluable sources of accurate information,
not only for use of the Government, but also for the general public. Of
the above-mentioned localities, 501 were in the public-land States and
427 in the Central, Eastern, and Southern States.
The chemical analyses of the coals found throughout the United States
have been made with such uniformity of method, both as to collection
of samples and analytical procedure, as to yield results strictly
comparable for coals from all parts of the country, and furnish complete
information, as a basis for future purchases and use by the Government
and by the general public, of all types of American coals.
Other researches have resulted in the acquirement of valuable
information regarding the distribution of temperature in the fuel bed of
gas producers and furnaces, showing a range of from 400° to 1,300°
cent., and have thus furnished data indicating specific difficulties to
be overcome in gas-producer improvements for greater fuel efficiency.
The recent studies of the volatile matter in coal, and its relation to
the operation of coke ovens and other forms of combustion, have
demonstrated that as much as one-third of this matter is inert and
non-combustible, a fact which may have a direct bearing on smoke
prevention by explaining its cause and indicating means for its
abatement.
Experiments in the storage of coal have proven that oxygen is absorbed
during exposure to air, thereby causing, in some cases, a deterioration
in heating value, and indicating that, for certain coals, in case they
are to be stored a long time for naval and other purposes, storage under
water is advisable.
The tests of different coals under steam boilers have shown the
possibility of increasing the general efficiency of hand-fired steam
boilers from 10 to 15% over ordinary results. If this saving could be
made in the great number of hand-fired boilers now being operated in all
parts of the United States, it would result in large saving in the fuel
bill of the country. Experiments which have been made with
residence-heating boilers justify the belief that it will be possible to
perfect such types of boilers as may economically give a smokeless
operation. The tests under steam boilers furnish specific information as
to the most efficient method of utilizing each of a number of different
types of coal in Government buildings and power plants in different
parts of the country.
The tests in the gas producer have shown that many fuels of such low
grade as to be practically valueless for steam-furnace purposes,
including slack coal, bone coal, and lignite, may be economically
converted into producer gas, and may thus generate sufficient power to
render them of high commercial value.
Practically every shipment out of several hundred tested in the gas
producers, including coals as high in ash content as 45%, and lignites
and peats high in moisture, has been successfully converted into
producer gas which has been used in operating gas engines. It has been
estimated that on an average there was developed from each coal tested
in the gas-producer plant two and one-half times the power developed
when used in the ordinary steam-boiler plant, and that such relative
efficiencies will probably hold good for the average plant of moderate
power capacity, though this ratio may be greatly reduced in large steam
plants of the most modern type. It was found that the low-grade lignites
of North Dakota developed as much power, when converted into producer
gas, as did the best West Virginia bituminous coals when utilized under
the steam boiler; and, in this way, lignite beds underlying from
20,000,000 to 30,000,000 acres of public lands, supposed to have little
or no commercial value, are shown to have a large value for power
development.
The tests made with reference to the manufacture and combustion of
briquetted coal have demonstrated conclusively that by this means many
low-grade bituminous coals and lignites may have their commercial value
increased to an extent which more than covers the increased cost of
making; and these tests have also shown that bituminous coals of the
higher grades may be burned in locomotives with greatly increased
efficiency and capacity and with less smoke than the same coal not
briquetted. These tests have shown that, with the same fuel consumption
of briquettes as of raw coal, the same locomotive can very materially
increase its hauling capacity and thus reduce the cost of
transportation.
The investigations into smoke abatement have indicated clearly that each
type of coal may be burned practically without smoke in some type of
furnace or with some arrangement of mechanical stoker, draft, etc. The
elimination of smoke means more complete combustion of the fuel, and
consequently less waste and higher efficiency.
The investigations into the waste of coal in mining have shown the
enormous extent of this waste, aggregating probably from 300,000,000 to
400,000,000 tons yearly, of which at least one-half might be saved. It
is being demonstrated that the low-grade coals, high in sulphur and ash,
now left underground, can be used economically in the gas producer for
power and light, and, therefore, should be mined at the same time that
the high-grade coal is being removed. Moreover, attention is now being
called to the practicability of a further large reduction of waste
through more efficient mining methods.
The washing tests have demonstrated the fact that many coals, too high
in ash and sulphur for economic use under the steam boiler or for
coking, may be rendered of commercial value by proper treatment in the
washery. The coking tests have also demonstrated that, by proper methods
of preparation for and manipulation in the beehive oven, many coals
which were not supposed to be of economic value for coking purposes, may
be rendered so by prior washing and proper treatment. Of more than 100
coals tested during 1906 from the Mississippi Valley and the Eastern
States, most of which coals were regarded as non-coking, all except 6
were found, by careful manipulation, to make fairly good coke for
foundry and other metallurgical purposes. Of 52 coals from the Rocky
Mountain region, all but 3 produced good coke under proper treatment,
though a number of these had been considered non-coking coals.
Investigations into the relative efficiency of gasoline and denatured
alcohol as power producers, undertaken in connection with work for the
Navy Department, have demonstrated that with proper manipulation of the
carburetters, igniters, degree of compression, etc., denatured alcohol
has the same power-producing value, gallon for gallon, as gasoline. This
is a most interesting development, in view of the fact that the heat
value of a gallon of alcohol is only a little more than 0.6 that of a
gallon of gasoline. To secure these results, compressions of from 150 to
180 lb. per sq. in. were used, these pressures involving an increase in
weight of engine. Although the engine especially designed for alcohol
will be heavier than a gasoline engine of the same size, it will have a
sufficiently greater power capacity so that the weight per horse-power
need not be greater.
Several hundred tons of peat have been tested to determine methods of
drying, compressing into briquettes, and utilization for power
production in the gas producer. In connection with these peat
investigations, a reconnoissance survey has been made of the peat
deposits of the Atlantic Coast. Samples have been obtained by boring to
different depths in many widely distributed peat-bogs, and these samples
have been analyzed and tested in order to determine their origin,
nature, and fuel value.
The extent and number of tests from which these results have been
derived will be appreciated from the fact that, in three years, nearly
15,000 tests were made, in each of which large quantities of fuel were
consumed. These tests involved nearly 1,250,000 physical observations
and 67,080 chemical determinations, made with a view to analyze the
results of the tests and to indicate any necessary changes in the
methods as they progressed. For coking, cupola, and washing, 596 tests,
of which nearly 300 involved the use of nearly 1,000 tons of coal, have
been made at Denver. For briquetting, 312 tests have been made.
Briquettes have been used in combustion tests in which 250 tons of
briquetted coal were consumed in battleship tests, 210 tons in
torpedo-boat tests, 320 tons in locomotive tests on three railway
systems, and 70 tons were consumed under stationary steam boilers. Of
producer gas tests, 175 have been made, of which 7 were long-time runs
of a week or more in duration, consuming in all 105 tons of coal. There
have been 300 house-heating boiler tests and 575 steam-boiler tests;
also, 83 railway-locomotive and 23 naval-vessel tests have been made on
run-of-mine coal in comparison with briquetted coal; also, 125 tests
have been made in connection with heat-transmission experiments, and
2,254 gasoline- and alcohol-engine tests. Nearly 10,000 samples of coal
were taken for analysis, of which 3,000 were from public-land States.
Nearly 5,000 inspection samples, of coal purchased by the Government for
its use, have been taken and tested.
The results of the tests made in the course of these investigations, as
summarized, have been published in twelve separate Bulletins, three of
which, Nos. 261, 290, and 332, set forth in detail the operations of the
fuel-testing plant for 1904, 1905, and 1906. Professional Paper No. 48,
in three volumes, describes in greater detail each stage of the
operations for 1904 and 1905.
Separate Bulletins, descriptive of the methods and results of the work
in detail, have been published, as follows: No. 323, Experimental work
conducted in the chemical laboratory; No. 325, A study of four hundred
steaming tests; No. 334, Burning of coal without smoke in boiler plants;
No. 336, Washing and coking tests of coal, and cupola tests of coke; No.
339, Purchase of coal under specifications on basis of heating value;
No. 343, Binders for coal briquettes; No. 362, Mine sampling and
chemical analyses of coals in 1907; No. 363, Comparative tests of
run-of-mine and briquetted coal on locomotives, including torpedo-boat
tests, and some foreign specifications for briquetted fuel; No. 366,
Tests of coal and briquettes as fuel for house-heating boilers; No. 367,
Significance of drafts in steam-boiler practice; No. 368, Coking and
washing tests of coal at Denver; No. 373, Smokeless combustion of coal
in boiler plants, with a chapter on central heating plants; No. 378,
Results of purchasing coal under Government specifications; No. 382,
The effect of oxygen in coal; and, No. 385, Briquetting tests at
Norfolk, Va.