Page 154 - Energy from Toxic Organic Waste for Heat and Power Generation

134 Energy from Toxic Organic Waste for Heat and Power Generation

this process is called combustion process and can be run in excess air
or required air ratio. Maximum level of combustion process is used
for conversion of water into steam or some electrical conversion
process. The waste product ash can be collected and refined in some
process; then it can be used in landfill or other construction work or
cement factories. In the refinery process, 99% of particulate matters
are removed from the ash.
b. Gasification: solid waste gasification is the process of unfair oxi-
dation of unwanted or waste form of fuel with addition of limited
amount of oxygen; it can be combust as a range of stoichiometric
process [21]. Different solid waste particles are broken down into mini
particles or carbon-based product can be converted into a feed stock
in the presence of certain oxidized compounds, and small amount
of carbon monoxide, hydrogen, and carbon dioxide [22]. In the gas-
ification process, in initial state heat can be supplied to start up the
gasification process [23]. The final produced gas is known as syngas.
Syngas can be utilized in different applications after cleaning method.
It is the one biggest challenge in the small- or large-scale plants. The
cleaned syngas can liberate high-liberate fuel, chemicals, or synthetic
natural gas. It can be utilized in efficient gas turbines or IC engines.
The heterogeneous character of the different waste fuel makes the gas-
ification process highly difficult together with the challenges of syngas
cleaning.
c. Pyrolysis: In the pyrolysis process, solid waste fuels are distinct as
a thermochemical decomposition waste fuel at high temperature;
it ranges between 500°C and 800°C. Without the oxygen content,
the different solid waste or MSW can be converted into syngas; in
liquid form, it is called tar, and in solid, char. The important aim of
pyrolysis process is to increase thermal decomposition of solid waste
to gases and condensed phases. The product in maximum heat is
liberated and other materials from the pyrolysis process are CO, H 2 ,
CH 4 , and other hydrocarbons. This ratio completely depends on the
pyrolysis temperature and amount of heating [24]. It is important to
note that the mechanical process ahead of gasification, compassion
to feedstock properties, less heating value of waste fuel, high-flue gas
clean-up systems, difficulty of syngas clean-up, and less performance
at small-scale industries have been a great difficult task during gasifi-
cation of MSW (Table 9.4).