Percentage of methane in coke oven gas may be around _____________________?

A. 5
B. 15
C. 25
D. 50

A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2. It means that___________________?

A. 21% excess air has been used for combustion
B. 21% excess oxygen has been used for combustion
C. Complete combustion of fuel has taken place
D. No excess air has been used for combustion

Which of the following combustibles is absent in blast furnace gas ?

A. H2
B. CH4
C. CO
D. None of these

Tolerable concentration of toxic carbon monoxide in atmospheric air is about ______________ ppm?

A. 50
B. 1000
C. 5000
D. 10000

Higher fuel combustion efficiency cannot be achieved by_________________?

A. Preheating of fuel gases & combustion air
B. Reducing sulphur content in the fuel
C. Adopting proper fuel firing technique & fuel preparation
D. Supplying correct amount of combustion air

A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is_________________?

A. CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60
B. CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02
C. CO2 : 6.39, CO : 1.60, O2 : 3.99, H2O:25.96, N2:72.06
D. CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

Softening temperature of coal ash is a measure of the _____________ of coal?

A. Caking tendency
B. Coking tendency
C. Clinkering tendency
D. Size stability

Calorific value of coke even gas produced by low temperature carbonisation of coal is about ____________ Kcal/Nm3?

A. 4000
B. 2500
C. 6500
D. 10000

During combustion of coal on grate, clinker formation is increased by the___________________?

A. Use of thick fire bed
B. Low fusion point of ash (< 1100° C)
C. Use of preheated primary air
D. All A., B. & C.

Short/intense flame is produced during combustion of gaseous fuel by using________________?

A. High amount/current of combustion air
B. Low amount/current of combustion air
C. Preheated secondary air
D. Very little excess air