Gas-Liquid Reaction - Lecture 1
-
Upload
girmaye-haile -
Category
Documents
-
view
741 -
download
0
Transcript of Gas-Liquid Reaction - Lecture 1
![Page 1: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/1.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
Gas - LiquidReaction Engineering
David W. Agar
Short Course
16th-25th June 2003
Chemical Engineering Department
IISc Bangalore
University of Dortmund
![Page 2: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/2.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
1997- Chair for Reaction Engineering,TCB Dortmund, D
1956 Danbury, England, GB
Curriculum Vitae
1980 Postdoctoral work Pasadena, CA, USA
1977-1980 PhD Chemical Engineering Houston, TX, USA
1981-1986 Central Research, BASF AG Ludwigshafen, D
1987-1990 Caprolactam plant, BASF AG Ludwigshafen
1990-1993 Coordinator for Isocyanate LudwigshafenResearch, BASF AG
1993-1995 Coordinator for Reaction LudwigshafenEngineering Research, BASF AG
1995-1996 Technical Support, Amine sales, Calgary, CDNBASF AG
1977 BSc Biochemical Engineering Swansea, Wales, GB
Ludwigshafen
![Page 3: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/3.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Course content:A survey of the most important gas-liquid reactions and the reactors
employed together with appropriate modelling & design fundamentals,
with special emphasis being placed on acid gas removal from syngas
& natural gas.
Recommended Reading:1. ‚Gas-Liquid Reactions‘ P.V. Danckwerts, McGraw-Hill, 1970
2. ‚Gas treating with chemical solvents‘ G. Astarita, D.W. Savage & A. Bisio, Wiley, 1982
3. ‚Gas Purification‘ A.L. Kohl & R.B. Nielsen, Gulf Publishing Co., 1997
![Page 4: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/4.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
25.06.03 Design problem
Course schedule:
16.06.03 Introduction to gas-liquid reactor
17.06.03 Chemistry of gas-liquid reactions
18.06.03 Reaction & diffusion
19.06.03 Reaction, diffusion & convection
20.06.03 Modelling of gas-liquid reactors
23.06.03 Determination of parameters
24.06.03 Exercises
![Page 5: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/5.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Solid
Gas
(2nd Liquid)
Liquid
Catalyst
Heterogeneous reaction systems
![Page 6: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/6.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundModelling analogies
• Non-catalytic gas-solid reactions- instantaneous reaction ⇔ shrinking core model- bulk phase reaction ⇔ homogenous conversion model
• Differences- heat effects slight- minimal changes in physical properties- fluid dynamics instead of porous solid structures- importance of phase equilibria- high separation factors
• Heterogeneously catalysed reactions- Ha ⇔ φ- E ⇔ h
• Reactor engineering- surface renewal ⇔ residence time distribution- M or Ha ⇔ Da
![Page 7: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/7.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Gas Liquid
Two film model
Boundary layers
Pha
sein
terfa
ce
Bulkphase
Bulkphase
A
CA0
pA0 CA*
pA*
• mass transferlocalised insurface films
• CA* & pA* at equilibrium
• continuity ofinterfacialflux
• no reaction ⇒const. slope
δLδG
![Page 8: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/8.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Gas LiquidSurface film
Pha
sein
terfa
ce
A
CA0
pA0
CA*
pA*
• very slow reaction
CB0
A(g) + B(aq) → C(aq)δL
![Page 9: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/9.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Gas Liquid
A
CA0
pA0
CA*
pA*
• moderate reaction
CB0
A(g) + B(aq) → C(aq)δL
![Page 10: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/10.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Gas Liquid
A
CA0=0
pA0
CA*
pA*
• fast reaction
CB0
A(g) + B(aq) → C(aq)
δL
![Page 11: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/11.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Gas Liquid
ApA0
CA*
pA*
• very fast reaction
CB0
A(g) + B(aq) → C(aq)
Rea
ctio
nfr
ont
δL
δR
![Page 12: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/12.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Gas Liquid
ApA0
CA*
pA*
• instantaneousreaction
CB0
A(g) + B(aq) → C(aq)
Reaction front =Phase interface
δL
δG
![Page 13: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/13.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundCO2(g) + 2 RNH2(aq) →
RNHCOO-(aq) + RNH3+(aq)
δL
CA [kmol/m³]1x10-5
0.6x10-5
0.2x10-5
CB [kmol/m³]
2
1
0.8x10-3
0.4x10-3
P[bar]
δG
δL
CA [kmol/m³]0.03
0.02
0.01
CB [kmol/m³]P[bar]
δG
2
1
0.5
0.3
0.1
δL
CA [kmol/m³]0.5x10-3
0.3x10-3
0.1x10-3
CB [kmol/m³]
2
1
P[bar]
δG
0.05
0.03
0.01
MonoethanolamineMEA: R=HOCH2CH2-
![Page 14: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/14.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Relative conversion as a function ofvolumetric utilisation factor & Hatta-number
reactive volume fraction
BC
Xrel
ATPC JR
BC: bubble column
AT: aerated tank
PC: packed column
JR: jet reactor
Ha =Reaction in film
Penetration thru‘ film
![Page 15: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/15.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Heat transport
Gas-Liquid reactors:problems & solutions
Phase interface
Homogenisation
Proprietary agitators
Extruder
Evaporative coolingFalling film reactor
Bubble column Spray tower Packed column
![Page 16: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/16.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Interfacial area
Heat exchangeHomogenisation
• two-phase pipe flow• venturi scrubber• spray tower• segmented reactor with gas injection• stirred tank with gas injection• packed column• tray column• loop reactor• bubble column• ….
⇒ scale-up⇒ bubble & solid⇒ distribution⇒ shearing⇒ stirrer power⇒ stirrer type
• evaporative cooling• falling film reactor• internal / externalheat exchangers
• ….
• three-phasefluidised beds
• fixed bed reactors- trickle- flooded
• slurry reactors- bubble column- stirred tank
• extruder reactor• jet mixer• loop reactor• …
Critical design features of gas-liquid-reactors
![Page 17: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/17.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundMixing of gas-liquid-reactors
Viscosity [Pas]<0.5 0.5-5 5-50
tang
entia
l -ra
dial
flow
axia
l flo
w
Types of agitator:
a) disc turbine
b) radial impellor
c) cross blade
d) gate paddle
e) flat blade paddle
f) anchor
g) axial impellor
h) propellor
i) MIG (Ekato)
j) spiral
![Page 18: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/18.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundCharacteristic mixing times
Re =
j n.t m
ρ.N.Di2
µ
e,es
f i
is
habs
b
e esis
i
bsa
c,cs=1.8e
d,ds=1.25e
tm<< τ
Types of agitator:a) disc turbine d) gate paddle g) axial impeller j) spiralb) radial impeller e) flat blade paddle h) propellerc) cross blade f) anchor i) MIG (Ekato) .s) baffled
tank
![Page 19: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/19.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Re
Ne
=P/
ρN3 D
i5
Mixing power requirements
Pg Qg N2Di4
P N.VL gWiVB2/3
-0.20 -0´25
= 0.1 ( ) ( )
Wi
N
us, Qg
Di
VB
(µ/ρ)³P/ρVR
0.25
δ = ( )
j
f c,cs,d,ds,e,es
i(s)b(s)
ashs es
asdscs
c,de hs
isbs
if,j
b
PgVR
0.4
kLa = 0.0026 us0.5( )Mass
transfercoefficient
δ << √(DAtm)
KolmogorovEddy size
![Page 20: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/20.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundHeat exchange in gas-liquid-reactors
a) Cooling/heatingjacket
b) Internalheatexchanger
c) Externalheatexchanger
d) Evaporativecooling
• facile maintenance• low external hold-up• flexible design
• intensive cooling• uniform T-profile• large reactors
![Page 21: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/21.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundHeat exchange ingas-liquid-reactors
e) Falling film reactor
![Page 22: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/22.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundHeat exchange vs. homogenisation
Heat removal (Qa) &
power dissipation (P)
of an anchor agitator
as a function of rota-
tional speed (n)
![Page 23: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/23.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundCreating interfacial area in gas-liquid-reactors
Gas-liquidcontactors
G = gas flow
L = liquid flow
Driving forces:
• pressure drop
• gravity
• mechanicalenergy
![Page 24: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/24.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundTaxonomy of bubble columns
a) Single stagebubble column
b) Multistagebubble column(sieve plate cascade)
c) Airlift reactors
upflow downflow jet-stream
![Page 25: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/25.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
![Page 26: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/26.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
![Page 27: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/27.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of DortmundTaxonomy of three phase reactors
a) Three phasefixed-bed reactor
b) Trickle bed reactor(or flooded operation)
c) Slurry reactors
bubblecolumn
stirredtank
fluidisedbed
![Page 28: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/28.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
![Page 29: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/29.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
• Catalyst in wire gauze envelopes avoids flooding• Catalyst in wire gauze envelopes avoids floodingReactive DistillationReaction requires:
• high liquid hold-up• bubbly flow / froth regime• low gas velocities• small catalyst particles• high catalyst loading
Reactive DistillationReaction requires:
• high liquid hold-up• bubbly flow / froth regime• low gas velocities• small catalyst particles• high catalyst loading
Distillation requires:• high interfacial areas• spray regime• open x-section for two phase flow
Compromise:• separate side-reactors• packing = 20-25% vol. of column
![Page 30: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/30.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Waste air purification: solvent recycling using absorption
pure gas
raw gas
pure gas
Absorbentmake-up
raw gas with
solventvapours
Strippingcolumn
Absorber
recoveredsolvent
rich absorbentabsorbent liquid distributor
packing
![Page 31: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/31.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Techniques for solvent regeneration
a) Flashing b) Inert stripping gas c) thermal stripping
![Page 32: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/32.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
![Page 33: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/33.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
![Page 34: Gas-Liquid Reaction - Lecture 1](https://reader034.fdocuments.us/reader034/viewer/2022042613/5527bd1e497959ec0f8b4ace/html5/thumbnails/34.jpg)
University of Dortmund – Chemical Engineering Department – Chair for Reaction Engineering
University of Dortmund
Course schedule:
16.06.03 Introduction to gas-liquid reactors
17.06.03 Chemistry of gas-liquid reactions
18.06.03 Reaction & diffusion
19.06.03 Reaction, diffusion & convection
20.06.03 Modelling of gas-liquid reactors
23.06.03 Determination of parameters
24.06.03 Exercises
25.06.03 Design problem