Which of the following contributes to boiler fouling?

Boiler fouling is primarily caused by the accumulation of oxidized materials and deposits on surfaces within the boiler system. Over time, this buildup of materials can restrict heat transfer, reduce efficiency, and increase fuel consumption. It can also lead to corrosion and other operational issues.

When boiler surfaces become coated with deposits such as soot, ash, and other particulate matter, they act as insulating layers that hinder the efficient transfer of heat from the combustion gases to the water or steam. This not only affects the performance of the boiler but can also lead to operational problems, requiring additional maintenance and cleaning to restore efficiency.

Although other factors like high-temperature operations, improper fuel types, and poor ventilation can influence boiler performance and contribute to the overall operational challenges, the direct link to boiler fouling is primarily through the accumulation of materials on heat exchange surfaces. This accumulation is the central concern when addressing fouling, making it the correct choice in this context.