The draft system in a boiler helps control the expulsion of which of the following?

The draft system in a boiler is primarily designed to manage the expulsion of flue gases. As combustion occurs in the boiler, it produces flue gases, which are a mixture of exhaust products including carbon dioxide, water vapor, and other combustion byproducts. Proper draft is necessary to ensure these gases are effectively vented to the atmosphere, preventing the buildup of harmful emissions and ensuring safety and efficiency within the system.

The operation of the draft system involves creating a pressure difference that draws the flue gases out of the combustion area and through the flue stack. This helps maintain the proper airflow, supports efficient combustion, and minimizes the chances of backflow, which could lead to incomplete combustion and carbon monoxide accumulation.

Managing the expulsion of flue gases is crucial for optimizing the performance of the boiler and maintaining compliance with environmental regulations. Therefore, the correct choice accurately reflects the primary function of the draft system in a boiler.