Page 71 - Wastewater Solids Incineration Systems

40 Wastewater Solids Incineration Systems

Sludge Analysis M.A.F.
Carbon 56.12%
Hydrogen 8.12%
Oxygen 26.22%
Nitrogen 6.94%
Sulfur 2.60%
HHV, Btu/Lbm M.A.F. 11,952
Percent Ash, Dry Basis 45.00%
FIGURE 4.2 Available heat from sludge incineration versus percent excess air (XS excess; M.A.F.
moisture ash-free; Btu/lb 2.326 kJ/kg; 0.555 6[°F] °C).

availability is negative and heat has to be added. Figure 4.2 shows a similar graph,
but in this case the x axis represents the percent of excess air used.
In Figure 4.3, the theoretical temperature of TTPC at 40% excess air versus a
feed cake heating value (Btu per pound of feed cake moisture [or kJ/kg in SI
units]) at three different air preheat temperatures is shown. Two additional lines
on Figure 4.3 represent 75% excess air and inlet air temperatures of 80°F and
1200°F (27°C and 649°C) for reference. The lower inlet air temperature case at 75%
excess air would correspond to the operating conditions of a typical multiple-
hearth furnace. The higher inlet air temperatures at 40% excess air, on the other
hand, typify a modern fluid bed system.