Which of the following methods is used to control boiler stack emissions?

The method of employing scrubbers, filters, and catalytic converters is widely recognized for controlling boiler stack emissions effectively. Scrubbers work by removing harmful pollutants from exhaust gases before they are released into the atmosphere. These systems use various chemical or physical processes to neutralize or capture contaminants such as sulfur dioxide, particulate matter, and nitrogen oxides.

Filters, often used in conjunction with scrubbers, can trap solid particles from the flue gas, further reducing the emission of pollutants. Catalytic converters also play a crucial role in converting harmful gases into less harmful substances through chemical reactions. This combination of technologies is essential in meeting environmental regulations and minimizing the impact of industrial emissions on air quality.

In contrast, using cooling towers primarily serves the purpose of cooling water systems and does not directly address the emission of gases. Implementing automatic blowdown systems is focused on maintaining water quality in the boiler rather than controlling stack emissions. Increasing the fuel-to-air ratio can affect combustion efficiency and performance but does not specifically target the reduction of emissions.