Question

In a pulverized fuel fired large power boiler, the heat transfer from the bringing fuel to the walls of the furnace is 

1.

by conduction only

2.

by convection only 

3.

by conduction and convection

4. predominantly by radiation 

Answer 1

Correct Answer - Option 4 : predominantly by radiation 

Concept:

A steam boiler is designed to absorb the maximum amount of heat released from the process of combustion.

Heat transfer within the steam boiler is accomplished by three methods: radiation, convection, and conduction.

• The heating surface in the furnace area receives heat primarily by radiation.
• The remaining heating surface in the steam boiler receives heat by convection from the hot flue gases. Heat received by the heating surface travels through the metal by conduction.
• Heat is then transferred from the metal to the water by convection.