Fuels and Combustion MCQs

1.Identify the incorrect statement from the following options:

LPG is commonly utilized as fuel for vehicles, small furnaces, and for metal cutting and welding.The flash point is the lowest temperature at which petroleum oil vapor ignites and sustains combustion.Distilling one ton of petroleum oil generates approximately 30-50 Nm³ of gas.The highest amount of naphthalene is produced during the distillation of crude oil.

2.Identify the incorrect statement from the following options:

A high oxygen level in flue gas indicates increased stack heat loss.Gaseous fuels need the smallest percentage of excess air to achieve complete combustion.The term 'fuel ratio' refers to the proportion of fixed carbon to volatile matter in coal.Natural gas has a higher calorific value compared to LPG.

3.Identify the item that does not belong to the group below:

Compressed fuel blocksTimberPetroleum gasMixture of pitch and creosote

4.What is the approximate percentage of carbon by weight in air-dried wood?

5.Among the following gases, which one possesses the lowest calorific value measured in kcal per Nm³?

Blast furnace gasGas from coke ovensBiogas produced from sewageMethane-rich natural gas

6.What does the turndown ratio of a gas burner represent?

The ratio between the highest and lowest heat inputThe ratio of the maximum to minimum allowable gas flowBoth the ratios mentioned in options A and BThe ratio of the lowest to highest heat input

7.Among the following gaseous fuels, which one possesses the lowest heat energy content?

8.How does the ignition temperature of a fuel in air compare to its ignition temperature in pure oxygen?

9.Eschka mixture, utilized for measuring sulfur content in coal, consists of which combination?

Magnesium oxide and sodium carbonateMagnesium sulfate and barium chlorideBarium sulfate and sodium chlorideMagnesium carbonate and sodium chloride

10.What is the effect of a higher ash content in coal used for making metallurgical grade coke?

Reduces the coke's hardnessLowers the coke's resistance to wearLeads to brittleness in the produced steelNone of the above

11.At approximately what temperature (in °C) is coal heated in the presence of air to measure its ash content during proximate analysis?

5007509501100

12.Which statement correctly describes the beehive coke oven?

Enables the collection of by-products during the coking processRequires 2 to 3 days to coke coal and operates without the need for external heating fuelYields a higher percentage of coke, approximately 85%, compared to by-product ovensGenerates coke that lacks adequate strength

13.When will the gross calorific value and net calorific value of a fuel be identical?

If the fuel contains no ashIf the fuel has a minimal amount of carbonIf the fuel lacks hydrogen or hydrogen-containing compoundsIn no situationIf the moisture content is zero

14.Which process is used for the commercial production of petrol from coal, such as in the Sasol plant in South Africa?

HydrogenationGasificationCarbonizationNone of the above

15.Which of the following statements accurately describes Fussain?

It is a brittle, charcoal-like material.Among the four banded coal components, it contains the greatest fixed carbon and the least volatile matter.Although it does not coke on its own, when mixed with strongly coking coal, it moderates swelling and yields high-quality coke upon carbonization.All of the above statements are true.

16.The explosive concentration range of blast furnace gas in a gas-air mixture lies between 37% and 71%. At what specific concentration percentage will the blast furnace gas ignite explosively when confined?

71%Between 37% and 71%Not applicable