Steam Boilers, Engines, Nozzles and Turbines
For maximum discharge through a chimney, the condition is that height of hot gas column producing the draught should be

One-half the height of chimney
Four times the height of chimney
Two times the height of chimney
Equal to the height of chimney

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Steam Boilers, Engines, Nozzles and Turbines
In forced recirculation type boiler,

Water is converted into steam in one pass without any recirculation
Feed pump is employed to supplement natural circulation in water wall type furnace
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

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