Steam Boilers, Engines, Nozzles and Turbines
Carbonization of coal is the process of

Pulverizing coal in inert atmosphere
Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
Heating wood in a limited supply of air at temperatures below 300°C
Binding the pulverized coal into briquettes

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Steam Boilers, Engines, Nozzles and Turbines
The efficiency of a boiler is defined as

Ratio of heat actually used in producing steam to the heat liberated in the furnace
Ratio of the mass of steam produced to the mass of total water supplied in a given time
Ratio of the heat liberated in the furnace to the heat actually used in producing steam
None of these

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