When carrying out a liquid-phase reaction nearly isothermally over extended reaction times, the most appropriate reactor type is a _________________ reactor?
Show answer Hide answer
Answer: A. Stirred tank
Explanation
Liquid-phase reactions with long residence times require vessels that accommodate extended holding periods. Stirred tank reactors allow continuous or batch operation over prolonged reaction durations easily. High liquid heat capacities make stirred tanks effective for maintaining near-isothermal operational conditions. Batch stirred tank reactors provide flexible reaction times for slow chemical manufacturing processes. Liquid-phase systems generally exhibit much higher densities and lower compressibility than gas systems. Isothermal operation prevents undesirable side reactions caused by uncontrolled thermal runaway conditions.
Pharmaceutical manufacturing often utilizes stirred tank reactors for slow organic synthesis reactions. Fine chemical production relies on batch stirred tanks for multi-step liquid-phase synthesis. Long reaction times make tubular reactors impractically long for liquid-phase batch processes. Tubular flow reactors are typically reserved for fast gas-phase reactions with short residence times. Fixed bed reactors are designed primarily for heterogeneous gas-solid catalytic reaction systems. Tubular reactors struggle to provide the very long residence times needed here economically.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Under constant density conditions, N identically sized mixed flow reactors connected in series with a combined volume V yield the same conversion as a single plug flow reactor of volume V, provided the feed rate, feed composition, and elementary first-order reactions are identical, when N equals ___________________?
Show answer Hide answer
Answer: C. ∞
Connecting multiple continuous stirred tank reactors in series reduces backmixing effects gradually. Each individual continuous stirred tank reactor acts as a partial stage toward plug flow. An infinite number of stages...
Q2. Which relationship applies to an isothermal variable-volume batch reactor undergoing an irreversible first-order reaction?
Show answer Hide answer
Answer: B. [CA0/(1 + εA XA)] (dXA/dt) = k
Variable volume systems experience significant density changes as chemical reactions proceed forward. The expansion parameter accounts for volume changes relative to reactant conversion levels. Accounting for volume chan...
Q3. Given identical feed composition and flow rates, connecting X plug flow reactors in series with a cumulative volume V achieves the same conversion as a single_______________?
Show answer Hide answer
Answer: B. PFR of volume V
Dividing a single plug flow reactor into smaller sections preserves overall residence time. Plug flow reactors connected in series behave identically to a single continuous tubular reactor. Cumulative volume represents t...
Q4. To achieve high conversion levels in a strongly exothermic solid-catalyzed reaction, one should employ a ______________ bed reactor?
Show answer Hide answer
Answer: B. Fluidised bed reactor followed by a fixed
Fluidized bed reactors offer superior temperature control for highly exothermic solid-catalyzed reactions. Fixed bed reactors provide high conversion efficiency for reaching completion in catalytic reactions. Combining f...
Q5. For series reactions, the relative yield__________________?
Show answer Hide answer
Answer: D. Both A. and C. hold good
Plug flow reactors maintain higher reactant concentrations than continuous stirred tank reactors at identical conversions. Higher reactant concentrations favor desired steps in series reaction networks to improve yield....
Q6. In a zero-order reaction, the concentration of the product increases in proportion to the _____________________?
Show answer Hide answer
Answer: A. Increase of reaction time
Zero-order reaction rates are completely independent of reactant concentrations in the system. The rate of product formation remains constant throughout the course of the reaction. Integrating a constant rate equation sh...