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

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Fuels and Combustion
Pick out the wrong statement.

Regulation of furnace temperature and atmosphere (oxidising or reducing) is easily possible with pulverised fuel firing
None of these
Low grade coal can be used, but generally high volatile matter coals are more suitable for making pulverised fuel
Pulverised fuel can be completely burnt with less percentage of excess air compared to lump coal

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Fuels and Combustion
Presence of free moisture in coal during its high temperature carbonisation

None of these
Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls
Increases the loss of fine coal dust from the ovens when charging
Reduces the coking time

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Fuels and Combustion
Sometimes water is sprayed during coal charging in the coke oven, which helps in

Reducing the cracking of hydrocarbons in the gas and increasing the percentage of CO & H₂ in the gas (due to the endothermic reaction represented by C + H₂O = CO + H₂)
Prevention of clinker formation in the oven
All of these
Controlling the dust nuisance while charging the coal

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