What is a retort used for in a boiler system?

A retort is primarily used in boiler systems for the process of fuel feeding, specifically in conjunction with underfeed stokers. In this context, a retort serves as a chamber where fuel is introduced and processed to enhance combustion efficiency. It allows controlled burning of solid fuels, such as coal, ensuring that the fuel is fed at a consistent rate into the combustion zone.

This method of fuel feeding improves the overall efficiency of heat generation within the boiler. The design of the retort helps in managing the air-to-fuel ratio and effectively burning the fuel to minimize unburned fuel waste and reduce emissions. By facilitating an optimized combustion process, the retort plays a critical role in the operation of the boiler.

The other options, while relevant in broader contexts of boiler operations, do not accurately describe the function of a retort. Cooling water refers to processes used to manage temperature rather than fuel feeding. Heat recovery relates to systems designed to reclaim waste heat for efficiency but is not specific to the function of a retort. Combustion gas purification refers to methods used to clean flue gases, which again is separate from the retort's role in fuel feeding.