30 real Reactor Design & Scale-up questions from the Process Design bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Batch vs continuous selection?
Junior
A.batch suits small volumes, multi-product plants and long reaction times; continuous suits large single-product plants with steady quality
B.loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
C.temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
D.RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
2. Which term means: "batch suits small volumes, multi-product plants and long reaction times; continuous suits large single-product plants with steady quality"?
A.Batch vs continuous selection — RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
B.Batch vs continuous selection — adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
C.Batch vs continuous selection — temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
D.Batch vs continuous selection — batch suits small volumes, multi-product plants and long reaction times; continuous suits large single-product plants with steady quality
A.average time material spends in a flow reactor, equal to reactor volume divided by volumetric flow at reactor conditions
B.adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
C.constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
D.jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
A.Residence time — average time material spends in a flow reactor, equal to reactor volume divided by volumetric flow at reactor conditions
B.Residence time — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
C.Residence time — differential (rate against concentration) or integral (fit concentration-time to an assumed order) analysis of batch data, with Arrhenius fitting across temperatures
D.Residence time — loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
A.controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
B.jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
C.RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
D.temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
8. Which term means: "jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow"?
A.Heat removal on scale-up — jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
B.Heat removal on scale-up — RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
C.Heat removal on scale-up — loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
D.Heat removal on scale-up — average time material spends in a flow reactor, equal to reactor volume divided by volumetric flow at reactor conditions
A.controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
B.temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
C.average time material spends in a flow reactor, equal to reactor volume divided by volumetric flow at reactor conditions
D.adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
11. Which term means: "controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry"?
A.Semi-batch dosing — jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
B.Semi-batch dosing — adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
C.Semi-batch dosing — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
D.Semi-batch dosing — constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
A.differential (rate against concentration) or integral (fit concentration-time to an assumed order) analysis of batch data, with Arrhenius fitting across temperatures
B.RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
C.jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
D.temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
14. Which term means: "temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process"?
A.Adiabatic temperature rise — temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
B.Adiabatic temperature rise — RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
C.Adiabatic temperature rise — constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
D.Adiabatic temperature rise — loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
A.controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
B.jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
C.adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
D.RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
17. Which term means: "RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up"?
A.Reaction calorimetry — RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
B.Reaction calorimetry — constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
C.Reaction calorimetry — temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
D.Reaction calorimetry — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
A.jacket duty is limited by U·A·ΔT, and since area scales with volume to the two-thirds power, heat removal per unit volume falls as vessels grow
B.constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
C.loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
D.adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
20. Which term means: "constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first"?
A.Mixing scale-up criteria — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
B.Mixing scale-up criteria — constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
C.Mixing scale-up criteria — RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
D.Mixing scale-up criteria — differential (rate against concentration) or integral (fit concentration-time to an assumed order) analysis of batch data, with Arrhenius fitting across temperatures
A.average time material spends in a flow reactor, equal to reactor volume divided by volumetric flow at reactor conditions
B.temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
C.constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
D.differential (rate against concentration) or integral (fit concentration-time to an assumed order) analysis of batch data, with Arrhenius fitting across temperatures
23. Which term means: "differential (rate against concentration) or integral (fit concentration-time to an assumed order) analysis of batch data, with Arrhenius fitting across temperatures"?
A.Kinetics from lab data — adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
B.Kinetics from lab data — loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
C.Kinetics from lab data — differential (rate against concentration) or integral (fit concentration-time to an assumed order) analysis of batch data, with Arrhenius fitting across temperatures
D.Kinetics from lab data — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
A.temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
B.adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
C.loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
D.constant power per unit volume, tip speed or blend time cannot all be held together, so the controlling mechanism must be chosen first
26. Which term means: "adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes"?
A.Time to maximum rate — adiabatic time for a runaway to reach peak rate; under 24 h at the maximum synthesis temperature demands safety measures in Stoessel's criticality classes
B.Time to maximum rate — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
C.Time to maximum rate — batch suits small volumes, multi-product plants and long reaction times; continuous suits large single-product plants with steady quality
D.Time to maximum rate — RC1-type measurement of heat release rate, total enthalpy and accumulation to fix safe dosing rates and cooling requirements before scale-up
29. Which term means: "loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins"?
A.Catalyst deactivation — loss of activity by sintering, coking or poisoning, handled by regeneration cycles, guard beds and end-of-run temperature margins
B.Catalyst deactivation — controlled addition of one reactant so accumulation stays low and the reaction remains dosing-controlled, the main defence against runaway in exothermic batch chemistry
C.Catalyst deactivation — average time material spends in a flow reactor, equal to reactor volume divided by volumetric flow at reactor conditions
D.Catalyst deactivation — temperature increase if all reaction heat stayed in the mass, ΔH·C/(ρ·Cp); values above about 50 K flag a runaway-prone process
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