what is the effectig of SOx and NOx 1

what is the effectig of SOx and NOx in the steam power plants equipments or it only effect on environmental?

 

[sciguyjim]

The effects would not only be environmental, but would also cause corrosion to metal in the power plant. The starting gases are corrosive on their own, but when SO3 gas combines with water vapor it produces sulfuric acid, H2SO4. NO2 gas combining with water will make nitric acid, HNO3. The two acids together are more corrosive than they are separately.

 

[mohtogh]

...In other words, it cause "Acid Rain". This is a global effect of SOx & NOx .

 

[25362]

In addition to what has been said earlier, corrosion in the economizer due to temperatures below the acidic SO2/SO3 dew point, whence the condensation products are diluted H2SO4 and H2SO3, is common. For that reason it is generally recommended to keep feedwater temperatures entering the economizer above 135 C and the flue gas economizer outlet above 160 C, in order to prevent condensation on the flue gas side. Ambient air inward leakage due to draft will tend to lower flue gas temperatures below the dew points resulting in localized corrosion of carbon steel.

Apart from being the principal contributors to acid rain, sulphuric and nitric acids undergo atmospheric transformation leading -or contributing- to the formation of PM10 in urban areas. It is relatively easy to remove SO2 from flue gases by absorption in water and reacting with alkali.

Air (N2+O2) is the source of NO at temperatures even at 1700 C and for a few milliseconds as in internal combustion engines -main polluters- where peak temperatures are in the range of 2200 C. Large coal fired heaters with preheating can reach peak temperatures of 1900 C with combustion times from 2 to 4 seconds !

NO is the principal nitrogen oxide present in flues. NO has a very low solubility in water. Unlike sulphur oxides that quickly react with water to form acids, NO must first be oxidized to NO2. So, wet limestone scrubbers are not efficient in the removal of NO.
NO and NO2 also play a significant role in the formation of unwanted ozone in the atmosphere.