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CHOICE OF REACTOR (II) Flow pattern Concentration Temperature Pressure Phase

Integrated Process Design. CHOICE OF REACTOR (II) Flow pattern Concentration Temperature Pressure Phase. PREVIOUS FACTORS: Reaction Path Reactions classification: single, parallel, series, mixed and polymerization. Reactor performance: conversion, yield and selectivity.

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CHOICE OF REACTOR (II) Flow pattern Concentration Temperature Pressure Phase

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  1. Integrated Process Design • CHOICE OF REACTOR (II) • Flow pattern • Concentration • Temperature • Pressure • Phase

  2. PREVIOUS FACTORS: • Reaction Path • Reactions classification: single, parallel, series, mixed and polymerization. • Reactor performance: conversion, yield and selectivity. • FACTORS TO BE CONSIDERED IN THE CHOICE OF THE REACTOR: • Target: Selectivity – Conversion – MW distribution • Flow pattern • Concentration • Temperature • Pressure • Phase

  3. BATCH / PLUG FLOW (PF) P F CONCENTRATION CONCENTRATION CONTINOUS STIRRED TANK REACTOR (CSTR) P F • Choice of Reactor • Flow pattern Idealized reactor models • No mixture between fluid elements. • Uniform residence time. • Perfect mixture between fluid elements. • Non-uniform residence time distribution.

  4. Single P Multiple in parallel F 1 CONCENTRATION CONCENTRATION 2 P F BATCH/PF CSTR • Fixed selectivity  Maximum conversion • Minimum volume: • Target: maximum selectivity

  5. 1 2 F1 F2 F2 F1 • Target: maximum selectivity

  6. 1 2 P 1 3 Mixed 2 F CONCENTRATION CONCENTRATION P Multiple in series F BATCH/PF CSTR • Target: maximum selectivity • Target: maximum selectivity Series (r1, r3): PF • a1 < a2→Consider mixed solutions: • CSTR in series • PF with recycle stream

  7. Polymerization • Target: molecular weight distribution Without termination stage: With termination stage:

  8. Single irreversible • Choice of Reactor • Concentration • Excess of one reactive to ensure complete conversion of another one (dangerous, difficult to separate, ...) Single reversible a) Modify feed ratio: shift equilibrium b) Dilution with an inert compound Caution: kinetics decrease c) Selective product removal

  9. 1 2 Multiple in paralell • Target: maximum selectivity.

  10. Single irreversible Single reversible • Choice of Reactor • Temperature To be considered: • Kinetics • Equilibrium • Reactants and products stability • Catalyst stability • Materials-of-construction limitations • Safety considerations a) Endothermic (ΔH > 0) b) Exothermic (ΔH < 0)

  11. 1 2 Multiple REACTOR TEMPERATURE CONTROL • Adiabatic reactors : preferred by simplicity and economy • Non-adiabatic reactors • Conventional heat transfer equipments (internal and external). • ‘Hot-shot’ / ‘Cold-shot’ • Inert addition (increase in mCp)

  12. Choice of Reactor • Pressure To be considered: • Liquid phase: Control phase changes • Vapor phase: • Kinetics: • Density: • Equilibrium. Single irreversible • Pmaximum Single reversible a) Δn < 0 b) Δn > 0

  13. Choice of Reactor • Phase • Preferably liquid: • Consider mass transfer in heterogeneous reactions

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