---------------------+----------+------------+---------------------+ | | | | | | | Products of | | | Oxygen | Combustion at 32 deg. F.| | Analyses | required +--------+------------+ | of 1 lb. | for | | | | of Coal. | Combustion.| Cubic | Volume | | | Pounds. | feet. | per cent. | ---------------------+----------+------------+--------+------------+ Carbon........... | 0.8497 | 2.266 | 25.3 | 11.1 | Hydrogen......... | 0.0426 | 0.309 | 7.6 | 3.4 | Oxygen........... | 0.0350 | --- | --- | --- | Sulphur.......... | 0.0042 | --- | --- | _ --- | Nitrogen......... | 0.1045 | --- | 0.18 | | | Ash.............. | 0.0540 | --- | --- | | | +----------+------------+ | | 85.5 | | | | | | | Total........... | 1.0000 | 2.572 | --- | | | 9-1/3.lb nitrogen | --- | --- | 118.9 | | | 6 lb. excess of air. | --- | --- | 71.4 | _| | +----------+------------+--------+------------+ Total cubic feet of | | | | | products per 1 lb. | | | | | of coal........... | -- | -- | 226.4 | 100.0 | ---------------------+----------+------------+--------+------------+ The temperature of the furnace not having been determined, we must calculate it on the supposition, which will be justified later on, that 50 per cent more air was admitted than was theoretically necessary to supply the oxygen required for perfect combustion. This would make 18 lb. of air per 1 lb. of coal; consequently 19 lb. of gases would be heated by 14,727 units of heat. Hence: 14,727 u. T = ---------------- = 3,257 deg. 19 lb. x 0.238 above the temperatures of the air, or 3,777 deg. absolute. The temperature of the smoke, _t_, was 849 deg. absolute; hence the maximum duty would be 3,777 deg. - 849 deg. --------------- = 0.7752. 3,777 deg. The specific heat of coal is very nearly that of gases at constant pressure, and may, without sensible error, be taken as such. The potential energy of 1 lb. of coal, therefore, with reference to the oxygen with which it will combine, and calculated from absolute zero, is: