Practical Hand Book of Gas, Oil and Steam Engines / Stationary, Marine, Traction; Gas Burners, Oil Burners, Etc.; Farm, Traction, Automobile, Locomotive; A simple, practical and comprehensive book on the construction, operation and repair of all kinds of engines. Dealing with the various parts in detail and the various types of engines and also the use of different kinds of fuel.

by John B. Rathbun

(16) Coal.

Coal which is the basis of producer gas, is composed generally speaking of the combustible matter, moisture, ash and sulphur. The combustible element may be subdivided into the HYDROCARBONS, OR VOLATILES, and the solid fixed carbon. The exact composition of coal is generally given by what is known as PROXIMATE analysis, which analysis divides the constituents of the coal into five groups, viz.: MOISTURE, VOLATILES, FIXED CARBON, ASH, and SULPHUR. Ultimate analysis resolves the coal into its ultimate chemical elements, such as hydrogen, carbon, nitrogen, sulphur, etc., and being a difficult and tedious process it is not much used.

The proximate analysis gives all the necessary information and takes less time to perform.

VALUES OF COAL
Location of Mine	PROXIMATE ANALYSIS					Calorific Value in B.T.U. per Lb. of Coal
	Moisture	Volatile Matter	Fixed Carbon	Ash	Sulphur
ANTHRACITE
Northern Pa.	3.39	4.41	83.30	8.17	.73	13,200
Eastern Pa.	3.70	3.07	86.42	6.18	.63	13,440
Western Pa.	3.12	3.76	81.60	10.61	.53	12,875
SEMI-ANTHRACITE	1.25	8.15	83.30	6.27	1.63	13,900
SEMI-BITUMINOUS
Pennsylvania	.80	15.60	77.40	5.35	.85	14,900
Pennsylvania	1.55	16.45	71.50	8.63	1.87	14,200
Pocahontas Va.	1.00	21.00	24.40	3.02	.58	15,100
West Virginia	.90	17.83	77.70	3.30	.27	15,230
BITUMINOUS
Youghiogheny Pa.	1.00	36.50	59.00	2.59	.86	14,400
Sample No. 2	1.20	30.18	59.00	8.84	.78	14,400
Hocking Valley	6.5	35.06	48.80	8.05	1.59	12,100
Kentucky	4.00	34.00	54.70	7.00	.03	12,800
Indiana	8.00	30.20	54.20	7.60		12,500
Illinois	10.50	36.15	37.00	12.90	3.45	10,500
Colorado	6.00	38.01	47.90	8.09		12,200
LIGNITE	9.00	42.26	44.30	3.27	1.18	11,000

The CALORIFIC VALUE of a fuel may be calculated from its analysis, or may be determined by means of the CALORIMETER from a sample of the coal; the latter method is the most reliable. Table gives approximately the calorific values, and the proximate analysis of several representative coals from various sections of the country. The values given in the table are not exact, as the coal from each locality varies considerably in quality, but the figures will indicate what may be expected from each type of coal.

Connellsville, Pa., Coke has a calorific value of approximately 13,000 B.T.U.’s per pound, contains no volatile matter, and has an approximate content of 10% ash. Coke is a valuable fuel for the gas producer, but is rather expensive. It is clean and the absence of volatile matter reduces the “scrubbing” problem to a minimum.

Small coal such as buckwheat and pea contain a much higher percentage of moisture than given in the table, running from 5% to 10% higher than the given values.

Bituminous coal is high in hydrocarbons or volatiles which condense easily and form tar. If the tar is not removed or converted into a permanent gas, it will clog the passages of the producer and the engine and cause trouble.

The removal of the tar and ash from a gas is called SCRUBBING, and is performed by a device much resembling a filter. Anthracite coal and coke are low in volatiles or hydrocarbons, and therefore do not cause trouble with tar deposits.

A high percentage of volatile matter also causes trouble by the tar cementing the particles of fuel together. This interferes with the proper action of the producer.

Fuels having a high percentage of ash call for perfect filtering or “scrubbing” as such fuels will fill the gas passages with dust. Dust should be kept out of the engine at all costs, for the dust even in a quantity will cause wear in the cylinder.

Depending on the quality of the fuel, bituminous coal will produce about 4½ pounds of ammonia and 12 gallons of tar with about 5% of sulphur.

Anthracite coal will produce approximately six pounds of tar, and two pounds of ammonia with traces of sulphur.

Loose Anthracite coal requires approximately 40 cubic feet of storage space per ton of 2240 pounds and weighs about 56 pounds per cubic foot (market sizes).

Loose Bituminous coal requires approximately 45 cubic feet of storage space per ton of 2240 pounds, and weighs about 52 pounds per cubic foot in market sizes.

Dry coke requires approximately 85 cubic feet of storage space per ton of 2240 pounds, and weighs about 26 pounds per cubic foot.