ChEn 433 Emissions
Class 3
Pollutants
List, categories
- Fossil fuel combustion
- NO\(_x\)
- SO\(_2\)
- CO
- Unburned Hydrocarbons
- Particulate
- CO\(_2\)
- Greenhouse gases
- CO\(_2\)
- CH\(_4\)
- Albedo effects (particulate)
Consider the roles of different energy sources in environmental impacts.
SO\(_2\)
SO\(_2\)
- Due to sulfur in fuel: coal, diesel, …
- S \(→\) SO\(_2\), SO\(_3\)
- all is converted (unlike NO\(_x\))
- \(y_{SO_2}/y_{SO_3} = 3570\) at equilibrium, but combustion SO\(_3\) is greater than at equilibrium, a few % of SO\(_2\).
- Utah coal example: C\(_{64}\)H\(_{32}\)N\(_{0.67}\)S\(_{0.3}\)O\(_{2.5}\), or 1% S by mass
- combustion \(→\) 822 ppmv SO\(_2\)
- SO\(_2\) \(→\) SO\(_3\) via OH in gas phase, or via \(H_2O\) absorption
- \(→\) H\(_2\)SO\(_4\) via H\(_2\)O \(→\) acid rain
Acid rain
From a castle in Westphalia,
Germany
SO\(_2\) Control
Remove S from the fuel
- Why is sulfur removed from gasoline?
Remove SO\(_x\) from efluent streams
Reduce SO\(_2\) with limestone or lime
- CaCO\(_3\) + SO\(_2\) + 2H\(_2\)O \(→\) CaSO\(_3\) \(⋅\) 2H\(_2\)O + CO\(_2\)
- CaO + SO\(_2\) + 2H\(_2\)O \(→\) CaSO\(_3\) \(⋅\) 2H\(_2\)O
SO\(_2\)
NO\(_x\)
- NO and NO\(_2\)
- Formed during combustion at high temperatures
- due to N in the fuel and N\(_2\) in air
- Control
- Combustion modifications
- Emission cleanup
NO\(_x\) combustion control
Low NO\(_x\) burner
NO\(_x\) post-combustion control
Selective
Catalytic Reduction (SCR)
Article: Managing the catalysts of a combustion turbine fleet.
NO\(_x\): Lake Side Power Station, Vinyard, UT
Particle sources, sizes
Particle terminal velocity
Particle environment
Baghouse
ESP
