This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Secondary Solid Fuels – 1”.
1. Which of the following is a secondary solid fuel?
Explanation: The fuels which are obtained from the solid fuels are called as secondary solid fuel. Charcoal is produced by the destructive distillation of wood. It is in the form of residue. Coke is also a secondary solid fuel.
2. By which type of coal does briquettes are made?
a) High grade fuel
b) Ultra high grade coal
c) Low grade fuel
d) High grade coal
Explanation: Briquettes are made by compressing low grade coal with or without binder (5-8% of coal tar or molasses). It helps us to utilize small-sized waste coal produced in mining and hence likely to be an important method as the best coal seems to get depleted.
3. How can we remove volatile matter form briquettes?
a) By baking them
b) By cooling them
c) By heating them
d) By applying some extra pressure
Explanation: The briquettes produced by mixing of the binder are baked to remove volatile matter present in it. Removing volatile matter from them will increase their calorific value to a certain point.
4. Which product is formed after the process of carbonisation?
b) Coal tar
c) Coal gas
Explanation: When the lignite coal is strongly heated out of contact with air, then coke is formed. Coke is used to smelt iron in the blast furnace process. It has the highest amount of carbon present in it.
5. Which type of coal gets soften on heating?
a) Caking coal
b) Coking coal
Explanation: On heating caking coal it gets soften producing a pasty mass which fuses together yielding coherent masses impervious to air. Coals that contains less pasty material are either non-caking or less caking in nature.
6. If the coke formed from the residue of the caking coal is hard, porous and strong then it is called coking coal.
Explanation: The so less caking material obtained from the caking coal is coke. All coking coals are caking coals but all caking coals are not coking coals.
7. Which of the following should be present in least amount, so as to give a good metallurgical coke?
a) Ash content
b) Moisture content
c) Volatile matter
d) Sulphur and phosphorous content
Explanation: Sulphur and phosphorous content in the coke can contaminate the metal and adversely affect its properties. They tend to make the metal brittle. Sulphur content should note be less than 0.5% and phosphorous 0.1%. Moisture should be less than 4% and ash content less than 6%.
8. Why should be a metallurgical coke porous in nature?
a) To increase its calorific value
b) To provide contact between carbon and oxygen
c) To decrease its ash content
d) For its easy storage
Explanation: When the metallurgical coke is porous then it becomes easy for the carbon present in it to make contact with oxygen so that the combustion process can be done efficiently of the fuel in the furnace. It increases the rate of combustion.
9. What happens when coke breaks into fine particles during the charging of the furnace?
a) It increases the rate of combustion
b) It cools down the temperature of furnace
c) It chokes the air passages
d) It stops the whole process
Explanation: When the coke break downs into fine particles, it hinders the flow of gases an choke the air passages. This happens due to the incomplete combustion of coke since it is broken into small pieces.
10. Why can coal not be used as a metallurgical fuel?
a) Because of its less purity
b) Due to its high calorific value
c) Due to the high cost of it
d) Due to the presence of less impurities
Explanation: Coal does not have necessary purity, porosity and strength. Coal can be used as metallurgical fuel only in reverberatory furnaces. This leads to incomplete combustion, thus affecting the metallurgical processes.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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