Biomass (waste to energy)

The basic technology for modern waste to energy combustion was developed in Europe during 1960s and 1970s. This technology, which has been modified and improved since its development, has been widely implemented in the US.






















Waste from Biomass (Agricultural waste, Municipal solid waste, Sewage, Wood & wood product) already consideration as fuel for energy and the sources for example, municipal solid waste as used herein refer to solid waste collected from residence and commercial, light industry and institutional waste.























The heating value each biomass can be calculated from Dulong’s formula:
HHV (BTU/lb) = 14,544 C + 62,028 [H2 – (O2/8)]
1 kJ/kg = 0.43Btu/lb

In the Europe, heating value is frequently express as the lower heating value (LHV)
LHV (BTU/lb) = HHV (BTU/lb) – [%H2O + (9 * %H2)] * (1050 BTU/lb) or
LHV (kJ/kg) = HHV (J/kg) – [(9 * % H2) + %H2O] * (2240 kJ/kg)

Excess air is generally monitored using an oxygen analyzer at the economizer outlet. The type of analyzer used at waste to energy facilities generally reports percent wet oxygen. The dry oxygen can be estimated by assuming 15% moisture in the flue gas using the follow equation
Dry oxygen = (wet oxygen) / [(1 – percent moisture)/100] or
Dry oxygen = 1.176 * (wet oxygen)

Excess air can be approximated by the following equation
Excess air = 55.2 – 10.46 *(dry O2) + 1.4 (dry O2)^2

The heat available for heating the products of combustion is the lower heating value (LHV) divide by the mean specific heat of the products of combustion.

The mean specific heat is a function of the constituent products of combustion (Wpc) and the temperature. To approximate the theoritical temperature attainable, one can use a specific heat of 0.55 BTU/lb per oF for water vapor (WH2O) and 0.28 BTU/lb per oF for the other gaseous products of combustion (Wpc – WH2O).

Thus the formula approximating the temperature attained during combustion is

T combustion oF = T ambient oF + [ (LHV BTU/lb) / (0.55 WH2O + 0.28 * (Wpc – WH2O)) ]

©Charles O Velzy (Consultant) & Leonard M Grillo (Grillo Engineering Company)