Which combination of systems is used to remove particulates and reduce NOx emissions from flue gas in a power plant?

• A. Electrostatic precipitator or baghouse for particulates; SCR or SNCR for NOx.
• B. Only electrostatic precipitator.
• C. Only SCR.
• D. Only baghouse.

Answer: (A)

Flue gas cleaning needs to address two different pollutants with appropriate, complementary devices. To remove solid particulates like fly ash, a particulate control device is used—either an electrostatic precipitator, which uses electric charges to make particles stick to collection plates, or a baghouse, which filters particles out with fabric filters. To lower NOx emissions, a NOx reduction process is used—either selective catalytic reduction, which uses a catalyst and a reducing agent (like ammonia) to convert NOx to nitrogen and water, or non-catalytic SNCR, which reduces NOx at high temperature without a catalyst.

Using both types of systems together is why this combination is the best answer: it ensures particulates are removed and NOx is reduced. Relying on only one system would leave either particulates or NOx uncontrolled, typically not meeting emission standards.