Fluidization Engineering Multiple Choice Questions & Answers (MCQs) on “Thermal Cracking”.
1. What kind of heat reaction is cracking reaction?
a) Exothermic
b) Endothermic
c) Constant
d) None of the mentioned
Answer: b
Clarification: Since naphtha is long chain, is requires energy to break the bond into smaller groups.
2. At what rate the coarse sand is circulated along with the feedstock?
a) 5 times
b) 10 times
c) 15 times
d) 20 times
Answer: d
Clarification: In order to maintain the temperature and not let the sand particles break down, high flow rate is maintained.
3. What is installed for for maintaining good contact across the fluidized bed?
a) Baffles
b) Cyclone separators
c) Electrostatic precipitators
d) All of the mentioned
Answer: a
Clarification: It acts as obstruction and creates turbulence inside the bed.
4. How are the formation of large bubbles can be eliminated?
a) Baffles
b) Cyclone separators
c) Electrostatic precipitators
d) All of the mentioned
Answer: a
Clarification: They breaks down the bubbles into smaller parts.
5. Apart from steam, what can be used to heat the crude oil?
a) Cracked oil
b) Oxygen
c) Nitrogen
d) Excess of crude oil
Answer: a
Clarification: Cracked oil is already at high temperature which helps in increasing the temperature of feed crude oil.
6. How is carbon-free sand separated from the lift gas?
a) Gravity
b) Pumping air
c) Flooding water
d) ALl of the mentioned
Answer: a
Clarification: Since they are heavier than lift gas, they settle down at the bottom.
7. What was the modification made by BASF for thermal cracking of crude oil?
a) Dual usage
b) Generates heat
c) Cracks crude oil
d) All of the mentioned
Answer: d
Clarification: BASF developed a single fluidized bed with dual purpose of heating and cracking crude oil.
8. What is the alternate for sand as a heat carrier?
a) Silica alumina
b) Coal
c) Ash
d) Saw dust
Answer: a
Clarification: Silica alumina have high specific heat and high thermal conductivity.
9. Considering the usage of two separate sections for heat generation and crude cracking provides advantage on which process?
a) Air can be used instead of oxygen
b) More oxygen can be utilized
c) No need of any air or oxygen supply
d) None of the mentioned
Answer: a
Clarification: Because there is no need for direct contact of oxygen as required for crude cracking, air can be used directly for heating purpose.
10. How many generators are required for generating 40,000 tons of ethylene/year?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: They used 2 generators for producing 40,000 tons of ethylene/year.
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