One way to estimate the energy content of wastes is based on an empirical equation described in Rhyner et al. (1995), which utilizes an elemental analysis (also called an ultimate analysis) of the material in question: HHV (kj/kg) = 339(C) + 1,440(H) – 139(O) + 105(S) where (C), (H), and (S) are the mass percentages of carbon, hydrogen, oxygen, and sulfur in dry material (for example, cardboard is 43.73 percent carbon, so C=43.73). For the following materials, find the higher heating values (HHV) of the dry waste and the HHV of “as received” waste accounting for the moisture content. Excel may be helpful. Now, assume a city’s waste is 10% corrugated boxes, 10% junk mail, 40% mixed garbage, 10% lawn grass, 10% demolition softwood, 10% tires, and 10% polystyrene. What is the average “as-received” HHV (kJ/kg) of this waste? Finally, how much waste needs to be burned per day to power a 4 MW power plant for the city? Assume the efficiency is 50% (that is, 50% of energy created goes to electricity generation).
One way to estimate the energy content of wastes is based on an empirical equation described in Rhyner et al. (1995), which utilizes an elemental analysis (also called an ultimate analysis) of the material in question:
HHV (kj/kg) = 339(C) + 1,440(H) – 139(O) + 105(S)
where (C), (H), and (S) are the mass percentages of carbon, hydrogen, oxygen, and sulfur in dry material (for example, cardboard is 43.73 percent carbon, so C=43.73). For the following materials, find the higher heating values (HHV) of the dry waste and the HHV of “as received” waste accounting for the moisture content. Excel may be helpful.
Now, assume a city’s waste is 10% corrugated boxes, 10% junk mail, 40% mixed garbage, 10% lawn grass, 10% demolition softwood, 10% tires, and 10% polystyrene. What is the average “as-received” HHV (kJ/kg) of this waste?
Finally, how much waste needs to be burned per day to power a 4 MW power plant for the city? Assume the efficiency is 50% (that is, 50% of energy created goes to electricity generation).
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