58
3 Advanced Technologies (Biological and Thermochemical) …
for cooking and heating in developing countries. Biomass in different forms can be
used for combustion to generate power and heat in small-scale and industrial-scale
applications. However, it usually needs certain processing operations on the wastes
such as sizing, drying and/or densification to make them more suitable as combustion
fuels. In order for combustion to be efficient and clean, the feedstock should be well
mixed and the operating conditions (e.g., temperature and time) should be optimized.
During combustion, biomass is subjected to a series of chemical reactions through
which carbon and oxygen of the biomass are oxidized to carbon dioxide and water
[8]. The main stages of the combustion process can be summarized as following
[8–11]:
– Heating and drying of the biomass/wastes.
– Pyrolysis of the dried biomass that generates gases and volatiles consisting of
carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ) and high molecular
weight compounds (tar).
– Combustion of the volatiles with oxygen in air.
– Oxidation of the char after all of the volatiles are burned off. Oxygen has to be
provided to sustain the pyrolysis and oxidation reactions where oxygen deficiency
can lead to incomplete combustion and formation of carbon monoxide.
The aim of this technology is to degrade the organics in MSW in the presence
of oxygen. The early incinerators were designed for MSW volume reduction, solidification and stabilization without recovery of energy. Recent incineration facilities
not only recover heat and energy, but also are designed to clean flue gas, utilize
different waste streams including wastewater as feedstock. They are capable of
reducing around 70% of the total mass and 90% of the volume of waste, respectively [12]. The schematic diagram of the incineration process is shown in Fig. 3.2.
The main concern of incineration is the production of GHG and their environmental
and human health impacts. However, advanced incinerators are equipped with Air
Pollution Control (APC) systems to lower the concentrations of particular matters,
CO 2 and SO 2 in the flue gas to meet the emission limit regulations. Some incinerators
Fig. 3.2 Schematic diagram of the incineration process. Reprinted and modified with permission
from Elsevier [12]
3 Advanced Technologies (Biological and Thermochemical) …
for cooking and heating in developing countries. Biomass in different forms can be
used for combustion to generate power and heat in small-scale and industrial-scale
applications. However, it usually needs certain processing operations on the wastes
such as sizing, drying and/or densification to make them more suitable as combustion
fuels. In order for combustion to be efficient and clean, the feedstock should be well
mixed and the operating conditions (e.g., temperature and time) should be optimized.
During combustion, biomass is subjected to a series of chemical reactions through
which carbon and oxygen of the biomass are oxidized to carbon dioxide and water
[8]. The main stages of the combustion process can be summarized as following
[8–11]:
– Heating and drying of the biomass/wastes.
– Pyrolysis of the dried biomass that generates gases and volatiles consisting of
carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ) and high molecular
weight compounds (tar).
– Combustion of the volatiles with oxygen in air.
– Oxidation of the char after all of the volatiles are burned off. Oxygen has to be
provided to sustain the pyrolysis and oxidation reactions where oxygen deficiency
can lead to incomplete combustion and formation of carbon monoxide.
The aim of this technology is to degrade the organics in MSW in the presence
of oxygen. The early incinerators were designed for MSW volume reduction, solidification and stabilization without recovery of energy. Recent incineration facilities
not only recover heat and energy, but also are designed to clean flue gas, utilize
different waste streams including wastewater as feedstock. They are capable of
reducing around 70% of the total mass and 90% of the volume of waste, respectively [12]. The schematic diagram of the incineration process is shown in Fig. 3.2.
The main concern of incineration is the production of GHG and their environmental
and human health impacts. However, advanced incinerators are equipped with Air
Pollution Control (APC) systems to lower the concentrations of particular matters,
CO 2 and SO 2 in the flue gas to meet the emission limit regulations. Some incinerators
Fig. 3.2 Schematic diagram of the incineration process. Reprinted and modified with permission
from Elsevier [12]