Environmental Engineering Reference
In-Depth Information
-
T
C
i
where
k
i
=
A
i
T
B
i
exp
------ -
.
The reaction constants,
A
i
,
B
i
, and
C
i
, were taken from Hanson and Salimian.
18
The OH radical concentration was taken from the main combustion calculation.
The O atom concentration was determined by the partial equilibrium approach given
as:
19
1
2
exp
-
C
T
[]
[]
=
B
O
AT
O
(3.28)
2
where
A
= 36.64,
B
= 0.5, and
C
= 27123.
3.4.1.2
Prompt NO
The model proposed by De Soete
20
was used to determine the prompt NO formation
rate.
[
]
d
NO
E
RT
[][
[
α
]
P
=
A
η
ONFuel
2
exp
(3.29)
2
dt
where η = 4.75 + 0.0819
N
c
- 23.2ϕ
2
- 12.2ϕ
3
.
The values of
A
and
E
were selected from Dupont et al.
21
The oxygen reaction
order, α , is related to the oxygen mole fraction in the flame and is given by De Soete.
20
3.4.1.3
NO Reduction Mechanism (Reburning)
NO reduction is a process where NO reacts with hydrocarbons, CH
i
, to form HCN
and other products. The NO reduction mechanism proposed by Bowman et al.
22
was
employed.
k
4
CH
+ →
NO
HCN
+
O
(R6)
k
CH
+ →
NO
HCN
+
OH
(R7)
5
2
k
CH
+ →
NO
HCN
+
H O
(R8)
6
3
2
-
T
C
i
where
k
i
=
A
i
T
B
i
exp
------ -
.
The values of
A
i
,
B
i
, and
C
i
are from Bowman et al.
22
The rate of destruction
for NO is given by
[
]
d
NO
[
]
[
[
]
[
[
][
]
+
]
+
]
R
=
k
CH
NO
k
CH
NO
k
CH
NO
(3.30)
4
5
2
6
3
dt
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