This set of Iron Making Multiple Choice Questions & Answers (MCQs) focuses on “Rist Diagram for Blast Furnace”.
1. Abscissa (i.e. horizontal axis) represents the __________
a) O/C atomic ratio in the gas
b) C/O atomic ratio in the gas
C) Fe/O atomic ratio in the gas
d) O/Fe atomic ratio in the gas
View Answer
Explanation: Abscissa (i.e. horizontal axis) represents the O/C atomic ratio in the gas. The top gas composition is at the top of the diagram. The O/Fe atomic ratio is shown along the ordinate, at the top, the O/Fe ratio is that of the unreduced ore.
2. The negative side of the ordinate below zero represents sources of oxygen other than iron oxide.
a) True
B) False
View Answer
Explanation: The negative side of the ordinate below zero represents sources of oxygen other than iron oxide, such as the air blast. Oxygen is injected through the tuyere region for the reduction of burden material.
3. The point in the Rist diagram, coordinates are (O/C)H and (O/Fe)H, is known as the __________
a) Thermal pinch point
b) Cross-over point
c) Pressure pinch point
d) Temperature pinch point
View Answer
Explanation: The point H in the Rist diagram, coordinates are (O/C)H and (O/Fe)H, is known as the thermal pinch point. The operating line rotates around H. This is an invariant point i.e. its position would not vary with the composition.
4. An ideal blast furnace has the highest efficiency.
a) True
B) False
View Answer
Explanation: An ideal blast furnace has the highest efficiency. Minimum coke rate is required for an operation of blast furnace in ideal condition. Efficiency means amount of coke required to produce one tonne of hot metal from the raw material through reduction.
5. The chemical pinch point corresponds to the ___________
a) Fe–FeXO–gas equilibrium
b) Fe–FeO–gas equilibrium
c) Fe–Fe2O3–gas equilibrium
d) Fe–Fe3O4–gas equilibrium
View Answer
Explanation: The chemical pinch point corresponds to the Fe–FeXO–gas equilibrium. It lines in the line with minimum permissible value of slope ncg. This line represents the best possible operating practice with a minimum coke rate.
6. The enthalpy versus temperature curve for the gas along the height of the blast furnace is represented by a ____________
a) Straight line
b) Vertical line
c) Horizontal line
d) Non-straight line
View Answer
Explanation: The heat capacity of the gas is assumed to be constant and independent of temperature. Hence, the enthalpy versus temperature curve along the height of the blast furnace is represented by a straight line.
7. The solid has a large heat capacity.
a) True
b) False
View Answer
Explanation: It is considered that solid has a large heat capacity. Solid burden undergo many types of endothermic reactions, situation is simplified by lumping all the endothermic heats together.
8. The chemical reserve zone is a part of the ___________
a) Thermal reserve zone
b) Hearth
c) Bosh
d) Stack
View Answer
Explanation: The chemical reserve zone is a part of the thermal reserve zone. At the CRZ, iron is present as a mixture of wustite (FexO) and metallic Fe, the gas phase has a constant composition.
Sanfoundry Global Education & Learning Series – Iron Making.
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