Steam:
Its Generation and Use

FUEL. The value of any fuel is measured by the num- ber of heat units which its combustion will gen- erate, a unit of heat being the amount required to heat one pound of water one degree Fahren- heit. The fuel used in generating steam is com- posed of carbon and hydrogen, and ash, with sometimes small quantities of other substances not materially affecting its value. “Combustible” is that portion which will burn ; the ash or residue varying from 2 to 36 per cent, in different fuels. Boiler House and Chimney for Babcock L ------------- TABLE OF COMBUSTIBLES. Kind of Combustible. Air Re- quired. Temperature of Com- bustion. Theoretical Value. Highest Attainable Value un- der Boiler. In Pounds per pound of Combustible. With Theoretical Supply of Air, With 1^ Times the Theoretical Supply of Air. With Twice the Theoretical Supply of Air. With Three Times the Theoretical Supply of Air. In Pounds of Water raised 1° per pound of Combustible. In Pounds of Water evaporated from & at 2120, with i lb. Combustible. With Chimney Draft. With Blast, Theor- etical Supply of Air at 60", Gas 320" Hydrogen Petroleum 36.00 15-43 575° 5°5° 3860 35J5 2860 2710 1940 1850 62032 21000 64.20 2i-74 18.55 19.90 (Charcoal, ) Carbon - Coke, 12.13 4580 32I5 244° 1650 1450° 15.00 13-3° 14.14 ( Anthracite Coal, ) Coal—Cumberland 12.06 4900 3360 255° 1730 15370 15-9° 14.28 15.06 “ Coking Bituminous ii-73 5'4° 352° 2680 1810 15837 16.00 14-45 I5-J9 “ Cannel 11.80 4850 333° 2540 1720 15080 15-6° 14.01 14-76 “ Lignite 9-3° 4600 3210 249° 1670 11745 12.15 10.78 11.46 Peat—Kiln dried 7.68 447° 3’4° 2420 1660 9660 10.00 8.92 9.42 6.78 “ Air dried 25 per cent, water... 5-76 4000 2820 2240 i55° 7000 7-25 6.41 Wood—Kiln dried 6.00 4080 2910 2260 i53° 7245 7-5° 6.64 “ Air dried 20 per cent, water.. 4.80 1 3700 2607 2100 1 1490 5600 5.80 4.08 4-39 There is a large difference in coals from different localities, and even adjacent mines. The following table of American coals, is compiled from various sources : AMERICAN COALS. COAL. STATE. KIND OF COAL. Per cent, of Ash. Theoretical Value. COAL. STATE. KIND OF COAL. Per cent I of Ash. Theoretical Value in Heat Units. Pounds of water evap. in Heat Units. Pounds of water evap. r— Penn. Anthracite .... “ Cannel ....... “ Connellsville.. “ Semi-bit’nous.. “ Stone’s Gas... “ Youghiogheny “ Brown ... Kentucky Caking.... “ Cannel.... “ Lignite.... 3-49 6.13 2.QO 15-02 6.5O 10.70 5.00 5.60 9-5° 2-75 2.00 14.80 7.00 14.199 13.535 14,22t i3,i43 i3>368 i3,i55 14,021 14,265 12,324 14,391 13,36° 9.326 14.70 14.01 14.72 13.60 13.84 13-62 14.51 14.76 12.75 14.89 16.76 13.84 9-65! Ill. Bureau Co “ Mercer Co “ Montauk Ind. Block “ Caking “ Cannel Md. Cumberland..;. Ark. Lignite Col. “ Ik u Texas “ Wash. Ter. Lignite.. Penn. Petroleum.... 5.20 5-6° 5-5° 2.50 5.66 6.00 13.88 5-o° 9.25 4-50 4-5° 3-4° 13,025 I3iI23 12,659 13,588 14.146 13.097 12,226 9.2I5 13-562 13,866 12,962 11.551 20,746 13-48 13-58 13.1° 14.38 14.04 13-56 12.65 9-54 14.04 M-35 I3-4I 11.96 21-47 The effective value of all kinds of wood per pound, when dry, is substantially the same. This is usually estimated at 0.4 the value of the same weight of coal. The following are the weights and comparative value of different woods by the cord: Kind of Wood. Hickory, Shell bark. “ Red heart. White Oak......... Red Oak........... Spruce............ New Jersey Pine... Wght. Kind of Wood. Wght. 4469 Beech 3126 3705 Hard Maple.... 2878 3821 Southern Pine.. 3375 3254 Virginia “ . 2680 2325 Yellow •' . 1904 2137 White “ . 1368 The first table gives, for the more com- mon combustibles, the air required for complete combustion, the temperature with different proportions of air, the theo- -tical value, and the highest attainable 53