SOx NOx

Question 1

Occurrence of sulfurs?

Answer 1

• Gypsum
• Coal (pyrites, organically bound, sulfates(
• Natural Gas (h2s)
• Crude oil (thyols and mercaptans)
• Ores (sulfides)

Question 2

SOx are mostly?

Answer 2

SO2 and some So3

Question 3

Evironmental and health effects of SOx?

Answer 3

Evironment - Reduced visibility, acidify water, acid rain (damages lots of stuff)

Health - Respiratory system, aggrivates asthma and broncchitis

Question 4

What way s can SOx be controlled

Answer 4

Prevention (removing sulfur from fuel) - low S coal, or cleaning fuel (gravity separation, sweetening, molecular sieves, amines)

• Control Technologies (dry/wet scrubbing, regnerable control eg filters)
• Removal of reduced S compounds (eg h2s) using solvents

Question 5

Mechanisms of SOx in coal combustion?

Answer 5

Sulfates - SO2 + oxides occur at 1400 degrees C

Pyritic S - FeS2 -> FeS + S (1100-1200 C)

Question 6

Flow chart for Coal power plant emissions removal

Answer 6

Power gen boiler - NOx removal (SCR) - particulate removal (ESP, bags etc) - Wet FGD (flue gas desulph) - stack

Question 7

Coal Desulfarization methods?

Answer 7

Physical Methods- Gravity sep, froth flotation, electro/magnetic separation

Chemical Methods- Using alkaline solutions (may hurt coal quality)

Biological methods - aerobic and acidic conditions to convert pyrite to sulfur

These methods only reduce S in pyrite form

Question 8

How does furnace desulfurization work?

Answer 8

-Injection of limeston/dolomite dust

Injected away from burners at lower temps, produces lots of ash

Question 9

Flue gas desulfurization?

Answer 9

Dry, wet and adsorbents.

Dry not used as much as wet and adsorbents not really at all (uses activated carbron)

Dry srubbing- Suits filter bags, possible regen, uses CaO or Ca(OH)2

Wet scrubbing - limestone slurries. Less dust, but corrosion and lowers gas temps leading to droops in plumes

Question 10

Sour Gas and oil

Answer 10

greater than 0.5% or less than 10% is considered

• generally present as oragno-s and small amount of h2s
• h2s separated using solvents and turned into S using claus process

Question 11

Nox during coal combustion?

NOX effects?

Answer 11

• 95% NO, 4-5 % NO2 rest is N2O
• Vehicles are bad for this
• Eye irritation , lung
• Smog, affets vegetation, acid rains, global warming, acidifying water

Question 12

NOx formation?

Answer 12

Fuel nox, Thermal nox (occurs increasingly as temps rise from 200 roughly.

• Prompt NOx
• Thermal nox dominant over 1500

Question 13

Ways to control NOx

Answer 13

• Reducing formation: (Low NOx burner), air staging, fuel staging, flue gas recycle
• Post Combustion Treatment: SCR or SNCR (both use ammonia) stands for selective catalyst reductions converts to water and nitrogen