heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

water is supplied in drum and through down-comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

feed pump is employed to supplement natural circulation in water wall type furnace

water is converted into steam in one pass without any recirculation

boiler effectiveness

boiler evaporative capacity

factor of evaporation

boiler efficiency.

can be raised rapidly

is raisd at slower rate

is raised at same rate

could be raised at fast/slow rate depending on design

20%

40%

50%

90%.

15%

20%

30%

45%