What do fire tubes in an HRT boiler contain?

• A. Warm water
• B. Hot gases
• C. Cold air
• D. Chemical agents

Answer: (B)

In an HRT (High Recovery Temperature) boiler, fire tubes are designed to carry hot gases produced from the combustion of fuel. These hot gases pass through the fire tubes and transfer their heat to the surrounding water, which is contained in the boiler shell. This heat exchange process is essential for generating steam or hot water efficiently.

The presence of hot gases in the fire tubes is crucial for the operation of the boiler. This design allows for effective thermal transfer, ensuring that the water can reach high temperatures quickly. The efficiency of the boiler system relies on optimizing this heat exchange, making the role of hot gases in the fire tubes vital for the overall performance and efficiency of the boiler. The other options do not relate to the function of fire tubes in an HRT boiler; they either represent substances that do not exist in this part of the system or are not involved in the heat transfer process necessary for the boiler's operation.