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A further complication is mixing. In general, more NO will form in the center of the reaction vessel and less near the walls, as the walls are cooler than the center. Thus, more ammonia must find its way to the center and less near the walls, otherwise NO in the center meets insufficient ammonia for
159:
The reaction requires a sufficient reaction time within a certain temperature range, typically 1,400 and 2,000 °F (760 and 1,090 °C), to be effective. At lower temperatures the NO and the ammonia do not react. Ammonia that has not reacted is called ammonia slip and is undesirable, as the
206:, the practical constraints of temperature, time, and mixing often lead to worse results in practice. However, selective non-catalytic reduction has an economical advantage over selective catalytic reduction, as the cost of the catalyst is not there.
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is between 1,400 and 2,000 °F (760 and 1,090 °C) to react with the nitrogen oxides formed in the combustion process. The resulting product of the chemical
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Although in theory selective non-catalytic reduction can achieve the same efficiency of about 90% as
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John L. Sorrels; David D. Randall; Carrie
Richardson Fry; Karen S. Schaffner (2019).
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When urea is used, the pre-reaction occurs to first convert it to ammonia:
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Being a solid, urea is easier to handle and store than the more dangerous
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Process to reduce nitrogen oxide emissions from power plants
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reduction and excess ammonia near the walls slips through.
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ammonia can react with other combustion species, such as
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In that case NO is produced instead of being removed.
54:
into the firebox of the boiler at a location where the
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At temperatures above 1093 °C ammonia oxidizes:
262:. The Babcock & Wilcox Company. pp. 34–13.
97:is described by the following simplified equation:
8:
46:. The process involves injecting either
215:
7:
240:Duo et al., 1992 Can. J. Chem. Eng,
156:), so it is the reactant of choice.
204:selective catalytic reduction (SCR)
225:"Selective Noncatalytic Reduction"
14:
20:Selective non-catalytic reduction
1:
298:Selective catalytic reduction
260:Steam: its generation and use
89:The conversion of noxious NO
328:
30:emissions in conventional
26:) is a method to lessen
62:reaction is molecular
256:Babcock & Wilcox
319:
274:
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258:Company (2005).
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187:-> 4 NO + 6 H
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287:How SNCR Works
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281:External links
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170:ammonium salts
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93:to innocuous N
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72:carbon dioxide
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28:nitrogen oxide
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32:power plants
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312:NOx control
168:), to form
101:4 NO + 4 NH
210:References
34:that burn
306:Category
293:See also
137:O → 2 NH
64:nitrogen
56:flue gas
150:ammonia
78:), and
48:ammonia
36:biomass
266:
228:(PDF)
183:+ 5 O
113:+ 6 H
109:→ 4 N
80:water
60:redox
40:waste
264:ISBN
254:The
179:4 NH
141:+ CO
129:CONH
86:O).
52:urea
44:coal
42:and
24:SNCR
164:(SO
152:(NH
133:+ H
105:+ O
74:(CO
70:),
50:or
308::
242:70
172:.
125:NH
82:(H
66:(N
38:,
272:.
230:.
191:O
189:2
185:2
181:3
166:3
154:3
143:2
139:3
135:2
131:2
127:2
117:O
115:2
111:2
107:2
103:3
95:2
91:x
84:2
76:2
68:2
22:(
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