Briefly about Reactor Systems • Examples of Industrial Reactors • Importance of the Reactor in the Process Process, Energy and System § Energy − wise (Thermal, Mechanical) § Economically (Equipment, Raw Materials and Products) • Equilibrium vs. Kinetics (Reaction Rate) • Exothermic vs. Endothermic Reactions • Briefly about Reactor Types (Models) • Reactor Parameters and Catalysts • Reactor/Separator Systems § Conversion, Selectivity, Yield § Purge, Recycles, etc. Reactor Systems T. Gundersen Reac 1
Example: The HDA Process Gas Recycle Purge Process, Energy and System Compressor H 2 Feed Flash REACTOR Drum Toluene Feed Toluene Recycle Fuel Gas TOLUENE COL. BENZENE COL. STABILIZER Benzene Diphenyl Reactor Systems T. Gundersen Reac 2
Reactors, Conversion and Selectivity Example: Toluene + H 2 = Benzene + CH 4 2 Benzene = Diphenyl + H 2 Process, Energy and System Conversion: X = (Toluene reacted) / (feed of Toluene) Selectivity: S = (produced Benzene) / (Toluene reacted) 1.00 Selectivity (S) 0.80 0.60 0.0036 0.40 = − S 1 0.20 ( ) 1.544 − 1 X 0.00 -0.20 Conversion (X) -0.40 -0.60 0.00 0.20 0.40 0.60 0.80 1.00 Reactor Systems T. Gundersen Reac 3
Reactors and Yield Process, Energy and System F F R F P R X y R = X × S R S P X y P = X × S × (1+ ω ) B P R R Conversion: X = ( R F - R X ) / R F Selectivity: S = ( P X / ( R F - R X ) ) * SF Recycle Ratio: ω = R R / F F Yield: y R = ( P X / R F ) * SF (reactor) y P = ( P / F F ) * SF (process) (SF is Stoichiometric Factor => S and y are (0-1) normalized) Reactor Systems T. Gundersen Reac 4
Briefly about Separation Systems • What do we mean by Separation ? Process, Energy and System § Cleaning, Purifying, Recovering • Decisions and Subtopics § Technology (Separation Method) § Optimal Design of one Separator § Sequence of Separators § Heat Integration of Separators • Separators in this Course § “Thermally driven” Separation Systems § Distillation (a lot), Evaporation (some) § Drying is not covered at all Separation Systems T. Gundersen Sep 1
Selection of Separation Method • Separate Phases Process, Energy and System § S/L, S/G, G/L, L/L è “Heterogeneous” • Separate Components in one Phase § è “Homogeneous” § Often generate a new Phase (Distillation) • Separation utilizes various Properties of the Phases and/or Components § Volatility, Solubility § Permeability, Particle Size § Density, Surface Properties, etc. Separation Systems T. Gundersen Sep 2
Vapor/Liquid Equilibrium and Distillation Material Balances (moles): F • X F,i = V • Y i + L • X i Process, Energy and System Equilibrium Relations: Y i = K i • X i Assume: K = diag (4.0 , 1.5 , 0.2) Y i kmole/h V , Y i A 0.474 10.88 B 0.404 9.27 C 0.122 2.80 X F,i kmole/h F , X F,i Tot 1.000 22.95 A 0.2 20.0 P,T B 0.3 30.0 Δ P C 0.5 50.0 X i kmole/h Tot 1.0 100.0 A 0.118 9.09 B 0.269 20.72 L , X i C 0.613 47.23 Tot 1.000 77.05 Separation Systems T. Gundersen Sep 3
Typical Flowsheet for Oil & Gas Separation Gas Further Drying Process, Energy and System and Compression From Well Oil Separation Systems T. Gundersen Sep 4
The “ultimate” VLE Separation is Distillation • Multiple VLE Stages Process, Energy and System § Stagewise with Trays § Continuous with Packing Material • Countercurrent Flow § Well-known Principle with optimal use of the Driving Forces • Tray Efficiencies § Too short Residence Time for Equilibrium at each Tray/Stage Separation Systems T. Gundersen Sep 5
Distillation can be complicated C1-C5 Process, Energy and System C6-C10 C13-C17 C18-C25 C26-60 Separation Systems T. Gundersen Sep 6
Distillation Columns and Energy • Typical Issues Process, Energy and System § Distillation is Energy intensive § Good Control of the Columns is important • Options to reduce Energy Consumption: § Best Sequence of Columns § Heat Integration between Columns § Integration with the “Background Process” § Use of a Heat Pump § Change Operating Parameters (pressure, reflux) § Change Column Configuration (“complex”) Separation Systems T. Gundersen Sep 7
• “Simple” Columns: Q C , T C , A C 1 § 1 feed, 2 products L Process, Energy and System D, x D § 1 reboiler, 1 condenser F, x F P • “Complex” Columns: V § > 1 feed N Q R , T R , A R § > 2 products (sidedraw) § Distributed reboiling and B, x B condensing (pumparound) Separation Systems T. Gundersen Sep 8
“Complex” Columns • Vapor Recompression § “Open” Heat Pump (next slide) Process, Energy and System • Thermal Coupling • Distributed Heat Exchange § Side Reboilers and Condensers • Side Strippers / Side Rectifiers • Prefractionation • Turbo Expander for Reflux • Multiple Feeds and/or Sidedraws • Examples of Complex Columns § Petlyuk, Dividing Wall, Kaibel, etc. Separation Systems T. Gundersen Sep 9
Vapor Recompression Process, Energy and System CW Feed W Distillate Bottoms Separation Systems T. Gundersen Sep 10
Sequence of Distillation Columns Problem Definition by Thompson and King, AIChE Jl, 1972: Process, Energy and System ”Given a mixture of N chemical components that is to be separated into N pure component products by using a selection of M separation methods” [ ] ⋅ − 2 ( N 1) ! = = Number of Sequences N Seq ⋅ − N ! ( N 1)! = = ⋅ − ( N 1) Number of Alternatives N N M Alt Seq Separation Systems T. Gundersen Sep 11
Example – Distillation Sequence Comp. Name Mole Frac. α =Ki/Kj ”CES” Process, Energy and System A Propane 0.05 2.00 5.26 B i-Butane 0.15 1.33 8.25 C n-Butane 0.25 2.40 114.50 D i-Pentane 0.20 1.25 13.46 E n-Pentane 0.35 Nadgir & Liu, AIChE Journal, 1983: F = min (D/B, B/D) Δ = ( α – 1) × 100 CES = f × Δ Separation Systems T. Gundersen Sep 12
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