User:Milton Beychok/Sandbox: Difference between revisions

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[[Image:Four Corners Power Plant.jpg|right|thumb|200px|{{#ifexist:Template:Four Corners Power Plant.jpg/credit|{{Four Corners Power Plant.jpg/credit}}<br/>|}}Flue gas emissions from a coal-fired power plant in [[New Mexico]].]]


'''Flue gas emissions from fossil fuel combustion ''' refers to the [[combustion]] product gas resulting from the burning of [[fossil fuel]]s <ref name=EPA>[http://www.epa.gov/ttn/chief/ap42/index.html Compilation of Air Pollutant Emission Factors]</ref>. 
Most fossil fuels are combusted with ambient air (as differentiated from combustion with pure [[oxygen]]) and this article is based on the use of ambient air as the combustion air.
== Discussion of flue gas components==
Since ambient air contains about 79 volume percent gaseous [[nitrogen]] (N<sub>2</sub>)<ref>{{cite book|author=Perry, R.H. and Green, D.W. (Editors)|title=[[Perry's Chemical Engineers' Handbook]]|edition=7th Edition|publisher=McGraw Hill|year=1997|id=ISBN ISBN 0-07-049841-5}}</ref>, which is essentially non-combustible, the largest part of the [[flue gas]] from most fossil fuel combustion is uncombusted nitrogen. The next largest part of the flue gas is [[carbon dioxide]] (CO<sub>2</sub>) which can be as much as 10 to 15 volume percent or more of the flue gas.  This is closely followed in volume by water vapor (H<sub>2</sub>0) created by the combustion of the hydrogen in the fuel with atmospheric oxygen.  Much of the 'smoke' seen exiting from [[flue gas stack]]s is this water vapor forming a fog cloud as it contacts cool air and condenses into water.
=== Flue gas pollutants ===
A typical flue gas from the combustion of fossil fuels will also contain some very small amounts of [[nitrogen oxide]]s (NOx), [[sulfur dioxide]] (SO<sub>2</sub>) and [[particulate matter]].<ref name=EPA/> The nitrogen oxides are derived from the nitrogen in the ambient air as well as from any nitrogen-containing compounds in the fossil fuel. The sulfur dioxide is derived from any [[sulfur]]-containing compounds in the fuels. The particulate matter is composed of very small particles of solid materials and very small liquid droplets which give flue gases their smoky appearance.
== Calculated flue gas emissions from burning fossil fuels ==
The steam generators in large [[power plant]]s and the process [[furnace]]s in large [[Petroleum refining processes|petroleum refineries]], [[petrochemical]] and [[chemical plant]]s, and [[incinerator]]s burn very considerable amounts of fossil fuels and therefore emit large amounts of flue gas to the ambient atmosphere. The table below presents the total amounts of flue gas typically generated by the burning of fossil fuels such as [[natural gas]], [[fuel oil]] and [[coal]]. The data in the table were obtained by [[stoichometry|stoichiometric]]<ref>{{cite book|author=Zumdahl, Steven S.|title=Chemical Principles|edition=5th Edition|publisher=Houghton Mifflin College Division|year=2005|id=ISBN 0-618-37206-7}}</ref>
calculations.<ref>[http://www.air-dispersion.com/formulas.html#combustion Air Dispersion Modeling Conversions and Formulas]</ref>
It is of interest to note that the total amount of flue gas generated by coal combustion is only 10 percent higher than the flue gas generated by natural gas combustion.
<center>'''EXHAUST FLUE GAS GENERATED BY COMBUSTION OF FOSSIL FUELS'''</center>
<Center>(In SI metric units and in USA customary units)</center><br>
<table style="border:1px solid black; border-collapse:collapse; width:88%;" align=center cellpadding=4>
<tr align=center>
<td align=left style="border:1px solid black;border-
collapse:collapse; width:58%;background:#F5F5F5;">'''Combustion Data'''</td>
<td style="border:1px solid black;border-collapse:collapse;background:#F5F5F5;">'''Fuel Gas'''</td>
<td style="border:1px solid black;border-collapse:collapse; background:#F5F5F5;">'''Fuel Oil'''</td>
<td style="border:1px solid black;border-collapse:collapse;width:13%;background:#F5F5F5;">'''Coal'''</td></tr>
<tr><td style="border:1px solid black;border-collapse:collapse;">'''Fuel properties:'''<br>
[[Heating value|Gross caloric value]], MJ / Nm³<br>
[[Heating value|Gross heating value]], Btu / scf<br>
Gross caloric value, MJ / kg<br>
Gross heating value, Btu / gallon<br>
Gross caloric value, MJ / kg<br>
Gross heating value, Btu / pound<br>
[[Molecular mass|Molecular weight]]<br>
[[Relative density|Specific gravity]]<br>
[[API gravity|Gravity]], °API<br>
[[Carbon]] / [[hydrogen]] ratio by weight<br>
weight % carbon<br>
weight % hydrogen<br>
weight % [[oxygen]]<br>
weight % sulfur<br>
weight % nitrogen<br>
weight % [[Coal assay#Ash|ash]]<br>
weight % [[Coal assay#Moisture|moisture]]<br>
'''Combustion air:'''<br>
Excess combustion air, %<br>
'''Wet exhaust flue gas:'''<br>
Amount of wet exhaust gas, Nm³/ GJ of fuel<br>
Amount of wet exhaust gas, scf / 10<sup>6</sup> Btu of fuel<br>
CO<sub>2</sub> in wet exhaust gas, volume %<br>
O<sub>2</sub> in wet exhaust gas, volume %<br>
Molecular weight of wet exhaust gas<br>
'''Dry exhaust flue gas:'''<br>
Amount of dry exhaust gas, Nm³/GJ of fuel<br>
Amount of dry exhaust gas, scf / 10<sup>6</sup> Btu of fuel<br>
CO<sub>2</sub> in dry exhaust gas, volume %<br>
O<sub>2</sub> in dry exhaust gas, volume %<br>
Molecular weight of dry exhaust gas<br>
</td>
<td align=center style="border:1px solid black;border-collapse:collapse;">&nbsp;<br>
43.01<br>
1,093<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
18<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
12<br>
&nbsp;<br>
294.8<br>
11,600<br>
8.8<br>
2.0<br>
27.7<br>
&nbsp;<br>
241.6<br>
9,510<br>
10.8<br>
2.5<br>
29.9<br>
</td>
<td align=center style="border:1px solid black;border-collapse:collapse;">&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
43.50<br>
150,000<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
0.9626<br>
15.5<br>
8.1<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
15<br>
&nbsp;<br>
303.1<br>
11,930<br>
12.4<br>
2.6<br>
29.0<br>
&nbsp;<br>
269.3<br>
10,600<br>
14.0<br>
2.9<br>
30.4<br>
</td>
<td align=center style="border:1px solid black;border-collapse:collapse;">&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
25.92<br>
11,150<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
&nbsp;<br>
61.2<br>
4.3<br>
7.4<br>
3.9<br>
1.2<br>
12.0<br>
10.0<br>
&nbsp;<br>
20<br>
&nbsp;<br>
323.1<br>
12,714<br>
13.7<br>
3.4<br>
29.5<br>
&nbsp;<br>
293.6<br>
11,554<br>
15.0<br>
3.7<br>
30.7<br>
</td></tr></table>
::Notes:
::(1) Normal cubic metres (Nm³) are at 0 °C and 101.325 kPa, and Standard cubic feet (scf) are at 60 °F and 14.696 psia.
::(2) The above table does not separate out the amounts of sulfur dioxide, nitrogen oxides or particulate matter.
==References==
{{reflist}}

Revision as of 19:41, 6 March 2008

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