Fuels and Combustion
Which of the following would require least amount of secondary air for combustion?

Semi-bituminous coal containing 25% ash and 20% volatile matter
Anthracite containing 10% volatile matter and 8% ash
Coke breeze containing 25% ash and 2% volatile matter
Bituminous coal containing 20% ash and 25% volatile matter

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Fuels and Combustion
Producer gas containing least amount of tar is produced by the

High pressure gasification of coal (e.g. in Lurgi gasifier)
Partial combustion of large size (< 50 mm) coke
Atmospheric pressure gasification of coal (e.g., in Kopper-Totzek gasifier)
Partial combustion of coal

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Fuels and Combustion
Low temperature carbonisation

Is mainly for producing the smokeless domestic coke
Produces less quantity of tar than high temperature carbonisation
Produces higher quantity of gas than high temperature carbonisation
Is meant for the production of 'metallurgical coke'

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