Briefly about Reactor Systems Examples of Industrial Reactors - - PowerPoint PPT Presentation

• T. Gundersen

Briefly about Reactor Systems

• Examples of Industrial Reactors
• Importance of the Reactor in the Process

§ 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.

Reac 1

Reactor Systems Process, Energy and System

• T. Gundersen

Example: The HDA Process

REACTOR TOLUENE COL. BENZENE COL. STABILIZER

Diphenyl Benzene Fuel Gas Toluene Feed Toluene Recycle H2 Feed Flash Drum Purge Compressor Gas Recycle

Reac 2

Reactor Systems Process, Energy and System

• T. Gundersen

Reactors, Conversion and Selectivity

Example: Toluene + H2 = Benzene + CH4 2 Benzene = Diphenyl + H2 Conversion: X = (Toluene reacted) / (feed of Toluene) Selectivity: S = (produced Benzene) / (Toluene reacted)

• 0.60
• 0.40
• 0.20

0.00 0.20 0.40 0.60 0.80 1.00 0.00 0.20 0.40 0.60 0.80 1.00

Conversion (X) Selectivity (S)

Reac 3

Reactor Systems Process, Energy and System

( )

1.544

0.0036 1 1 S X = − −

• T. Gundersen

Conversion: X = ( RF - RX ) / RF Selectivity: S = ( PX / ( RF - RX ) ) * SF Recycle Ratio: ω = RR / FF Yield: yR = ( PX / RF ) * SF (reactor) yP = ( P / FF ) * SF (process)

(SF is Stoichiometric Factor => S and y are (0-1) normalized)

Reactors and Yield

R S FF RR P PX RX RF BP

yR = X×S yP = X×S×(1+ω)

Reac 4

Reactor Systems Process, Energy and System

• T. Gundersen

Briefly about Separation Systems

• What do we mean by Separation ?

§ 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

Sep 1

Separation Systems Process, Energy and System

• T. Gundersen

Selection of Separation Method

• Separate Phases

§ 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
• f the Phases and/or Components

§ Volatility, Solubility § Permeability, Particle Size § Density, Surface Properties, etc.

Sep 2

Separation Systems Process, Energy and System

• T. Gundersen

Vapor/Liquid Equilibrium and Distillation

XF,i kmole/h A 0.2 20.0 B 0.3 30.0 C 0.5 50.0 Tot 1.0 100.0 Yi kmole/h A 0.474 10.88 B 0.404 9.27 C 0.122 2.80 Tot 1.000 22.95 Xi kmole/h A 0.118 9.09 B 0.269 20.72 C 0.613 47.23 Tot 1.000 77.05

P,T ΔP

F , XF,i V , Yi L , Xi

Material Balances (moles): F • XF,i = V • Yi + L • Xi Equilibrium Relations: Yi = Ki • Xi Assume: K = diag (4.0 , 1.5 , 0.2)

Sep 3

Separation Systems Process, Energy and System

• T. Gundersen

Typical Flowsheet for Oil & Gas Separation

Sep 4

Separation Systems Process, Energy and System

Further Drying and Compression Gas Oil From Well

• T. Gundersen

The “ultimate” VLE Separation is Distillation

Sep 5

Separation Systems Process, Energy and System

• Multiple VLE Stages

§ 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

• T. Gundersen

Distillation can be complicated

C1-C5 C6-C10 C13-C17 C18-C25 C26-60

Sep 6

Separation Systems Process, Energy and System

• T. Gundersen

Distillation Columns and Energy

Sep 7

• Typical Issues

§ 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 Process, Energy and System

• T. Gundersen

F, xF QC , TC , AC QR , TR , AR L P V B, xB D, xD

1 N

Sep 8

• “Simple” Columns:

§ 1 feed, 2 products § 1 reboiler, 1 condenser

• “Complex” Columns:

§ > 1 feed § > 2 products (sidedraw) § Distributed reboiling and condensing (pumparound)

Separation Systems Process, Energy and System

• T. Gundersen

“Complex” Columns

Sep 9

• Vapor Recompression

§ “Open” Heat Pump (next slide)

• 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 Process, Energy and System

• T. Gundersen

W Distillate Bottoms Feed CW

Vapor Recompression

Sep 10

Separation Systems Process, Energy and System

• T. Gundersen

Sequence of Distillation Columns

Sep 11

Separation Systems Process, Energy and System

Problem Definition by Thompson and King, AIChE Jl, 1972:

”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”

[ ]

Seq ( 1) Alt Seq

2 ( 1) ! Number of Sequences ! ( 1)! Number of Alternatives

N

N N N N N N M

−

⋅ − = = ⋅ − = = ⋅

• T. Gundersen

Example – Distillation Sequence

Sep 12

Separation Systems Process, Energy and System

Comp. Name Mole Frac. α=Ki/Kj ”CES” 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