Page 105 - Energy from Toxic Organic Waste for Heat and Power Generation

90 Energy from Toxic Organic Waste for Heat and Power Generation

7.4.1 Incineration
Incineration or burning provides one among the main passage for the paper
and board industry waste management at present. The primary positive aspect
of this technique is that the large volume reduction that have to be disposed of
and the great ability for recovering energy, which can make further econom-
ical gains in “green” energy. In contrast to these beneficial facts, it has some
drawbacks like requirement of huge principal investments, formation of ashes
at the end of process, chances of air emission and its measures, need of dewa-
tering and/or drying as a predecessor in order to increase the heating value of
most sludge, and rejects containing high- moisture and inorganic contents [10].
Fluidized bed combustors can be used for these wastes since it was found
as superior in effectiveness for such fuels with high-moisture contents and
it has lower emissions benefit also. The incineration of plastics-containing
rejects also necessitates the consideration of their chlorine content into ac-
count by reason of equipment corrosion and emission concerns [11, 12].
Another opportunity is to use some hybrid approaches like co-firing of
paper industry sludge with other type wastes, for example, with biomass or
coal, etc. [13–15].

7.4.2 Gasification
Gasification typically involves the fractional oxidation of the materials by
air, O 2 , and/or steam for the creation of gas mixture that is primarily com-
posed of CO, CH 4 , CO 2 , H 2 O, and N 2 , which is a more handy energy
carrier than heat and can also be supplied as a feedstock for the chemical
production. And it can also be
• Utilized in combustion engines or gas turbines,
• Converted into liquid fuels, or
• Reformed to hydrogen-rich gas.
Considering the wastes that are with high-moisture contents is likely to
generate reduced calorific value gas and the gases cannot uphold thermal
conversion processes (high-temperature). So the moisture content must be
reduced at the initial stage itself to a level that is less than 15% by the way of
evaporative drying [16]. Number of researches on paper and board indus-
try waste gasification are existing [17, 18], for instance, fixed bed gasification
optimally applied in rejects of mills utilizing PfR, either with wood chip co-
gasification or with prearrangement of rejects for the plastics content removal.
The first business gasifier for the paper and board industry will come
to operation soon at Netherlands which will process 25,000 tons of rejects
per annum. The developed synthesis gas is planned to be used for steam