Agriculture Reference
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and developing technologies to control the risks associated with contaminants.
Let us consider thermal processing as a class of hazardous control technology that
is widely used in treating wastes but which has crucial pollution components.
THERMODYNAMICS AND STOICHIOMETRY
If completely organic in structure, contaminants are, in theory, completely de-
structible using principles based in thermodynamics with the engineering inputs
and outputs summarized as
hydrocarbons
+
O
2
(
+
energy?)
ā
CO
2
+
H
2
O(
+
energy?)
(3.1)
Contaminants are mixed with oxygen, sometimes in the presence of an external
energy source, and in fractions of seconds or several seconds the by-products of
gaseous carbon dioxide and water produced exit the top of the reaction vessel
while a solid ash is produced and exits the bottom of the reaction vessel.
13
Energy may also be produced during the reaction and the heat may be recovered.
Although CO
2
and H
2
O production is a measure of success, a derivative problem
in this simple reaction could be global warming associated with carbon dioxide.
Conversely, if the contaminant of concern to the engineer contains other
chemical constituents, in particular chlorine and/or heavy metals, the original
simple input and output relationship is modified to a very complex situation:
+
+
+
+
hydrocarbons
O
2
(
energy?)
Cl or heavy metal(s)
H
2
O
+
inorganic salts
+
nitrogen compounds
+
sulfur compounds
+
phosphorus compounds
ā
CO
2
+
H
2
O(
+
energy?)
+
chlorinated hydrocarbons or heavy metal(s) inorganic salts
+
nitrogen compounds
+
sulfur compounds
+
phosphorus compounds
(3.2)
With these contaminants the potential exists for destruction of the initial con-
taminant, but actually exacerbating the problem by generating more hazardous
off-gases containing chlorinated hydrocarbons and/or ashes containing heavy
metals (e.g., the improper incineration of certain chlorinated hydrocarbons can
lead to the formation of the highly toxic chlorinated dioxins, furans, and hex-
achlorobenzene). All of the thermal systems discussed below have common at-
tributes. All require the balancing of the three āT'sā of the science, engineering,
and technology of incineration of any substance:
1. Time of incineration
2. Temperature of incineration
3. Turbulence in the combustion chamber
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