Part 18 (1/2)
Carbon is by far the most abundant as is indicated in the chapters on fuels
Hydrogen in a free state occurs in small quantities in some fuels, but is usually found in combination with carbon, in the foren is 00696 (Air = 1) and its weight per cubic foot, at 32 degrees Fahrenheit and under atmospheric pressure, is 0005621 pounds
Sulphur is found in most coals and some oils It is usually present in combined form, either as sulphide of iron or sulphate of lime; in the latter form it has no heat value Its presence in fuel is objectionable because of its tendency to aid in the forases from its combustion, when in the presence of en is drawn into the furnace with the air Its density is 09673 (Air = 1); its weight, at 32 degrees Fahrenheit and under atmospheric pressure, is 007829 pounds per cubic foot; each pound of air at aten, and one pound of nitrogen is contained in 1301 pounds of air
Nitrogen perforh the furnace without change It dilutes the air, absorbs heat, reduces the temperature of the products of combustion, and is the chief source of heat losses in furnaces
Calorific Value--Each coen in certain definite proportions and will generate a definite amount of heat, measured in B t u This definite amount of heat per pound liberated by perfect combustion is terives certain data on the reactions and results of combustion for elementary combustibles and several compounds
TABLE 31
OXYGEN AND AIR REQUIRED FOR COMBUSTION
AT 32 DEGREES AND 2992 INCHES
Colus:
1: Oxidizable Substance or Coht 4: Cheen per Pound of Coluen per Pound of Column 1 332[23] O Pounds 8: Air per Pound of Column 1 432[24] O Pounds 9: Gaseous Product per Pound of Column 1[25] + Column 8 Pounds 10: Heat Value per Pound of Colu Co with Column 11 Volume 13: Volumes of Product Formed Volume 14: Volume per Pound of Coluen per Pound of Column 1 Cubic Feet 16: Volume of Products of Coen per Pound of Column 1 3782[26] Column 15 Cubic Feet 18: Volume of Gas per pound of Column 1 = Column 10 Column 17 Cubic Feet
BY WEIGHT ________________________________________________________________________ | | | | | | | | 1 | 2 | 3 | 4 | 5 | 6 | |________________|_______|____|________________|_________________|_______| | | | | | | | | Carbon | C | 12 | C+2O = CO_{2} | Carbon Dioxide | 2667 | | Carbon | C | 12 | C+O = CO | Carbon Monoxide | 1333 | | Carbon Monoxide| CO | 28 | CO+O = CO_{2} | Carbon Dioxide | 571 | | Hydrogen | H | 1 | 2H+O = H_{2}O | Water | 8 | | | | / CH_{4}+4O = | Carbon Dioxide | | Methane | CH_{4}| 16 | | | 4 | | | | CO_{2}+2H_{2}O | and Water / | | Sulphur | S | 32 | S+2O = SO_{2} | Sulphur Dioxide | 1 | |________________|_______|____|________________|_________________|_______|
________________________________________________________ | | | | | | | | 1 | 2 | 7 | 8 | 9 | 10 | |________________|_______|_______|_______|_______|_______| | | | | | | | | Carbon | C | 885 | 1152 | 1252 | 14600 | | Carbon | C | 443 | 576 | 676 | 4450 | | Carbon Monoxide| CO | 190 | 247 | 347 | 10150 | | Hydrogen | H | 2656 | 3456 | 3556 | 62000 | | | | | | | | | Methane | CH_{4}| 1328 | 1728 | 1828 | 23550 | | | | | | | | | Sulphur | S | 332 | 432 | 532 | 4050 | |________________|_______|_______|_______|_______|_______|
BY VOLUME
________________________________________________________________ | | | | | | | | 1 | 2 | 11 | 12 | 13 | 14 | |_________________|________|______|____|________________|________| | | | | | | | | Carbon | C | 1C | 2 | 2CO_{2} | 1495 | | Carbon | C | 1C | 1 | 2CO | 1495 | | Carbon Monoxide | CO | 2CO | 1 | 2CO_{2} | 1280 | | Hydrogen | H | 2H | 1 | 2H_{2}O | 17932 | | Methane | CH_{4} | 1C4H | 4 | 1CO_{2} 2H_{2}O| 2241 | | Sulphur | S | 1S | 2 | 1SO_{2} | 560 | |_________________|________|______|____|________________|________|
_____________________________________________________________ | | | | | | | | 1 | 2 | 15 | 16 | 17 | 18 | |_________________|________|_______|________|________|________| | | | | | | | | Carbon | C | 2989 | 2989 | 11298 | 14287 | | Carbon | C | 1495 | 2989 | 5649 | 8638 | | Carbon Monoxide | CO | 640 | 1280 | 2420 | 3700 | | Hydrogen | H | 8966 | 17932 | 33909 | 51841 | | Methane | CH_{4} | 4483 | 6734 | 16955 | 23689 | | Sulphur | S | 1121 | 1121 | 4239 | 5360 | |_________________|________|_______|________|________|________|
It will be seen from this table that a pound of carbon will unite with 2-2/3 pounds of oxygen to form carbon dioxide, and will evolve 14,600 B t u As an intermediate step, a pound of carbon en to form carbon monoxide and evolve 4450 B t u, but in its further conversion to CO_{2} it would unite with an additional 1-1/3 ti 10,150 B t u When a pound of CO burns to CO_{2}, however, only 4350 B t u
are evolved since the pound of CO contains but 3/7 pound carbon
Air Required for Combustion--It has already been shown that each combustible eleen
With the ultimate analysis of the fuel known, in connection with Table 31, the theoretical amount of air required for combustion may be readily calculated
Let the ultimate analysis be as follows:
_Per Cent_ Carbon 7479 Hydrogen 498 Oxygen 642 Nitrogen 120 Sulphur 324 Water 155 Ash 782 ------ 10000
When complete combustion takes place, as already pointed out, the carbon in the fuel unites with a definite aen, either in a free or coen to foren shown in a fuel analysis, however, is available for the production of heat, as a portion of it is already united with the oxygen shown by the analysis in the forhts of H and O are respectively 1 and 16, the weight of the coen, and the hydrogen available for combustion will be H - 1/8 O In complete combustion of the sulphur, sulphur dioxide SO_{2} is formed, which in solution in water forms sulphuric acid
Expressed numerically, the theoretical amount of air for the above analysis is as follows: