Steam Boilers, Engines, Nozzles and Turbines
Coke is produced by

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

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Steam Boilers, Engines, Nozzles and Turbines
In fire tube boilers

Forced circulation takes place
None of these
The flames and hot gases pass through the tubes which are surrounded by water
Water passes through the tubes which are surrounded by flames and hot gases

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Steam Boilers, Engines, Nozzles and Turbines
In designing air preheaters, the important design consideration is that

Stack gases should not be cooled to the dew point
Handling and maintenance should be easier
Approach temperature should be as low as possible
Heat transfer area should be optimum

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