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

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

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Fuels and Combustion
Calorific value of

Light paraffinic fuel oils is lower than that of equivalent olefins
N-paraffin is lower than that of iso-paraffins of the same compounds
Light paraffinic fuel oils is equal to that of equivalent olefins
Light paraffinic fuel oils is higher than that of equivalent olefins

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Fuels and Combustion
A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the

Presence of large quantity of hydrogen in the fuel
High sulphur content in the fuel
Low calorific value of the fuel
Lack of thorough mixing of fuel with air

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