Block 1 - Controlling Combustion Emissions Flashcards
Which of the following is a major component of smog?
O3
What is the major disadvantage of using the SNCR process compared to SCR?
Lower effectiveness in reducing NOx
How does the SCR process operate to reduce NOx emissions?
By injecting a reductant to react with NOx over a catalyst
Which gas is primarily formed during combustion and accounts for about 95% of NOx emissions?
NO
What is the role of the burner damper in flue gas recirculation?
To control the flow of recirculated gases
What is the primary reason NOx is considered an environmental problem?
It initiates reactions that produce ozone and acid rain
How do air registers help in reducing CO emissions?
By controlling the amount of air supplied
What is the main environmental impact of VOCs?
They contribute to smog formation and climate change
Which of the following methods is used to reduce CO emissions by controlling the shape of the flame?
Flame Retention Head
How does photolysis of NO contribute to the formation of VOCs?
By producing ozone, which reacts with hydrocarbons
How much NOx reduction can be achieved by using flue gas recirculation?
Up to 50%
What is the purpose of refractory materials in combustion chambers?
To promote complete combustion and reduce CO
What is the purpose of using the Ultra-Lean Premix method for NOx control?
To minimize NOx formation by maximizing air in the fuel-air mix
What is the key difference between Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR)?
SCR uses a catalyst, while SNCR does not
What are the two principal nitrogen pollutants generated by gas-fired equipment?
NO and NO2
What happens when excess air is used in a combustion process?
It reduces CO by forming CO2
What is flue gas recirculation (FGR) used for in combustion processes?
To reduce the production of NOx by lowering flame temperature
Which of the following is a potential downside of using steam injection to control NOx levels?
Reduction in efficiency by 3-10%
What is the main chemical reagent used in Selective Non-Catalytic Reduction (SNCR)?
Ammonia
What is the typical efficiency of SCR in reducing NOx emissions?
90% or more
