Application of PI in the process industries, review and analysis of 20 cases
Author:
Henk van den Berg
Introduction
Twenty applications of Process Intensification in the process industries have been reviewed.
The objectives are given in the contribution to the 5th International PI Conference, Maastricht
October 13-15, 2003.
This report section contains extended descriptions of the twenty applications
Items to be considered are given in a standard format below
No
xx
author-title
“author”- “title”
ref.
organisation
Process objectives
“company, institution”
Existing / start situation
Process overall, as black box including raw materials and products
Process functions:
* chemical / reaction
* separations
New, consider:
* process synthesis, project organisation
* technical challenges
* conservation laws
* separate or combine functions
Results
Related info
Summary
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 1
No
1
author-title
ref.
Jeffrey J. Siirola – Synthesis of equipment with integrated
functionality
1st Dutch PI Symposium “Profits for the chemical industry”, 7 May
1998, Rotterdam. See also
AIChE Symp Series 91(304), 222 (1995)
Advances in Chemical Engineering, 23, 1 (1996)
Eastman Chemical Company
organisation
Process objectives
Create more efficient process
In the introduction the following general issues are discussed:
- Systematic approaches to process synthesis: evolutionary modification, systematic
generation which builds up a flowsheet from specifications of what is to be accomplished
(selected in the case discussed), superstructure optimization
- Means-ends analysis to systematic flowsheet generation concentrates on detecting the
differences between current state and products and specifying technologies to overcome
these differences. Approach in a hierarchical manner: component identity (reaction),
followed by amount or flowrate, concentration, phase, temperature, pressure, and finally
size and shape.
- Concentration on tasks to be accomplished, in equipment task integration can be realized
Existing / start situation
Methyl acetate is used as an example. Reaction: methanol + acetic acid <=> methylacetate +
H2O, an acid catalyzed, slightly exothermic reaction, equilibrium system.
Methylacetate and water form a homogeneous azeotrope, no simple separartion by distillation
or decantation. Methylacetate and methanol form a homogeneous low boiling azeotrope.
Removal will lower conversion.
No techniques were available to design a unit that combines the three tasks:
- produce methylacetate
- produce water
- recycle excess feed
So heuristic approach used, result was/is plant containing: 1 reactor, 1 extractor, 1 decanter, 8
distillation columns, introduction of 2 mass separation agents. Conventional process, 13 unit
operations.
Process overall, as black box including raw materials and products
Methyl acetate process; raw materials: acetic acid and methanol, products: methylacetate and
water
Process functions:
* chemical / reaction
challenge: to influence equilibrium and simplify complex
* separations
separations (several components, two azeotropes)
New, consider:
* process synthesis, project organisation
Redesign by task oriented approach is applied
* technical challenges
* conservation laws
* separate or combine functions
Combination of functions has been applied
Results
Total process in a single column, 80 m tall, 80% less expensive and 80% less energy as
conventional plant
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 2
Related info
several publications by Siirola
Summary
Systematic approach for task integration in process design leads to intensified process
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 3
Conventional Approach to
Methyl Acetate Process Synthesis
Acetic Acid
Methanol
Catalyst
Methyl
Acetate
Solvent
Water
Azeo
Water
Heavies
Solvent/Entrainer
Water
Task
Task Orientation
Orientation
♦
♦ Address
Address property
property differences
differences in
in aa hierarchical
hierarchical
fashion
fashion
♦
♦ Think
Think specifically
specifically in
in terms
terms of
of tasks
tasks to
to be
be
accomplished,
accomplished, not
not equipment
equipment to
to be
be used
used
♦
♦ Identify
Identify tasks
tasks not
not necessarily
necessarily in
in the
the same
same
direction
direction as
as material
material flow
flow
♦
♦ Specify
Specify tasks
tasks at
at different
different levels
levels in
in the
the design
design
hierarchy
hierarchy in
in aa coordinated
coordinated manner
manner
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 4
Task Approach to Methyl Acetate
Process Synthesis
(Removes Methanol
and Water)
(Removes Water
and Acetic Acid)
Solvent-Enhanced
Distillative Separation
Task
Distillative
Separation
Task
Acetic Acid
Catalyst
Methanol
Equilibrium
Reaction
Task
Methyl Acetate
Methanol
Water
Acetic Acid
Recycle to Somewhere
Water
Acetic
Acid
Methyl AcetateWater Azeo
Methanol
(Removes Acetic Acid)
Distillative
Separation
Task
Distillative
Separation
Task
(Removes Methyl Acetate
and Methanol)
Water
Acetic Acid
Recycle to Somewhere
Task Integration for Process Intensification
Integrated Methyl Acetate Process
Acetic Acid
Catalyst
Methanol
Distillation
Task G
Methyl Acetate
Extractive
Distillation
Task F
Reactive
Distillation
Task E
Reaction
Task A
Reactive
Distillation
Task B
Distillation
Tasks
C and D
Water
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 5
No
2
author-title
ref.
organisation
I. Turunen – Intensification of the anthraquinone process for
production of hydrogen peroxide
I. Turunen, H. Haario, M. Piironen – Control system of an
intensified gas-liquid reactor
Proceedings 2nd International Conference on PI, 1997, p 99,
Proceedings 3rd International Conference on PI, 1999, p 61
Turunen: Kemira Chemicals Oy, Lappeenranta University of
Technology, Haario: University of Helsinki, Piironen: Kemira
Process objectives
Improve economics by combination of reaction and separation and enhanced mass transfer
Existing / start situation
Two step process – in both steps reaction + separation:
1. Hydrogenation of anthraquinone
2. Oxidation to hydrogen peroxide formation
3. Anthraquinone is used as a carrier, reactions take place in organic solvents = working
solution
4. Conventional oxidation reactor: air bubbling through packed or empty bubble column.
H2O2 is extracted from the organic medium by water
5. Extraction
6. Purification
7. Concentration
See blockdiagram
Process overall, as black box including raw materials and products
New process: combine reaction and separation, enhance mass transfer, oxygen feed
Process functions:
* chemical / reaction
* separations
Tested: Tubular reactor + static mixers, several O2 feed points. Kinetics and mass tranfer
studies applied. Model for G/L reaction: mass transfer coefficient, Sh number, interfacial area.
Calculated: volume fraction gas, interfacial area, O2 conc, Ha number, H2O2 conc
Conclusion: mass transfer effects oxidation rate in first half of reactor, where the reaction rate
is fast due to high concentrations. In first half high Ha numbers
Notes:
- feeds O2 only in first half of the reactor.
- no information about: reaction rates or kinetics, temperatures
New, consider:
* process synthesis, project organisation
* technical challenges
* conservation laws
* separate or combine functions
New reactor with enhanced mass transfer, using oxygen feed. Detailed reactor model has been
developed. Calculated O2 feed rates over the feed points are used to control the capacity.
Results
Small reactor compared to conventional bubble column
Smaller amount of working solution and smaller plant size
Second part
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 6
New
Combination of oxidation reaction and extraction – tubular reactors + gas separation + liquid
separation, counter current extraction
Used for efficient separation of H2O2 and organics
Oxidation reactor contains three phases. Oxidation takes place in the organic solute, H2O2 to
transfer to water phase. Concept developed with model and pilot tests. See basic diagram.
Results
Large extraction columns replaced by much smaller units and combined with oxidation
reaction.
Size of combined reactorors+extraction is almost the same as reactors for oxidation only.
Third part: Fixed bed hydrogenation of anthraquinone
Existing
Pd catalyst particles suspended in the working solution. Problem: catalyst removal after
hydrogenation and before oxidation
New
fixed catalyst bed – catalyst is fixed inside structures made of metal net
efficient G/L mixing by packing
Results
- Less investment – no filtration and catalyst losses
- Longer catalyst life
H2
Hydrogenation
O2 or air
Oxidation
H2O
Drying
Extraction
working solution
Purification
aquous solution of H2O2
Concentration
Production of hydrogen peroxide by anthraquinone process
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 7
Summary
Process functions improved:
- hydrogenation
- oxidation
- reaction
- separation
Challenges: improve economics by combination of reaction and separation and enhanced mass
transfer, leading to smaller and more efficient process
Hydrogenation
Existing / problem: catalyst separation and losses
New:
fixed catalyst bed – catalyst is fixed inside structures made of metal net
efficient G/L mixing by packing
Results:
less investment – no filtration and catalyst losses
longer catalyst life
Oxidation
New process: oxygen feed
Tubular reactor + static mixers, several O2 feed points
Model for G/L reaction
Results:
Small reactor
Smaller amount of working solution and plant size
Oxidation and extraction
New: Concept developed with model and pilot tests
Results: Large extraction columns replaced by much smaller units and combined with
oxidation reaction.
Process application realized
Related info
water
O2
gases
reactors, main part
of H2O2 formed
working
solution,
hydrogenated
Basics new proces: Countercurrent set up
Left side conversion in tubular reactors
reaction, separation
of gas and liquids
H2O2 35%
working
solution,
0,03%H2O2
Right side: complete conversion and
separate by extraction
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 8
No
3
author-title
A. Meili – Practical process intensification shown with the
example of a hydrogen peroxide distillation system
Proceedings 2nd International Conference on PI, 1997, p 309
Sulzer Chemtech Ltd
ref.
organisation
Process objectives
Increased safety, less costs --> lowest temperature, minimum hold up, reliable+safe system
Existing / start situation
Conventional distillation plant, column provided with trays and external reboiler and
condensor. Large hold up of component that can decompose and can form explosive mixtures.
Feed 37% H2O2, product 70% H2O2
Process overall, as black box including raw materials and products
Relates to Concentration part of H2O2 plant, see also Turunen
Note: Concentration function in Turunen case not included in extraction section, product is
feed for concentration section
Process functions:
* chemical / reaction
* separations
case related to separation only
New, consider:
* process synthesis, project organisation
not shown
* technical challenges
* conservation laws
application not shown
* separate or combine functions
Intensification by:
- Combination of all main items of equipment in one unit with very little pressure drop and
small product hold-up – no external reboiler and condensor
- Climbing wall reboiler connected to the bottom of the column, a lamella type separator
above this, column provided with stuctured packings, a direct condensor which allows
small temperature differences between process and cooling water, no interconnecting
piping needed – all efficient equipment and low liquid content
- Lowest possible operating temperature
- Application of heat pumps
Results
Small decomposition rate, a high yield, very safe operation conditions and low costs.
Single column concept with new packing: 30% reduction of column diameter and utilities.
Heat pump also applied will reduce utilities to 30% of conventional tray column.
Industrial applications realized
Related info
US patent 5,171,407
European patent 0 419 406 B1
Note: Meili is additional to Turunen. Read Turunen first
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 9
Summary
Keywords/essentials:
Integration of conventional reboiler and condensor in the distillation column, including new
packing
Heat pump application
Results: Small decomposition rate, a high yield, safe operation conditions and 30% or more
reduction of utility costs.
Reduced pressure drop
•
•
•
less inter pipe connections
decrease of operating temperatures
reduced H2O2 decomposition
Minimized liquid H2O2 hold-up
•
reduced decomposition potential
Minimized installation space
•
smaller plot area
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 10
No
4
author-title
ref.
M.A.T. Bisschops, L.A.M. van der Wielen, K.Ch.A.M. van der
Wielen – Centrifugal adsorption to remove volatile organic
compounds from water
Proceedings 2nd International Conference on PI, 1997, p 299
Delft University of Technology
organisation
Process objectives
Demonstrate potentials of Centrifugal Adsorption Technology
Removal of diluted components from large aqueous streams
Existing / start situation
Traditionally done in fixed beds. Improved by countercurrent operation in moving packed bed
and multistage fluidised bed. Even particles 500µm-1mm result in large beds with substantial
pressure drop
Process overall, as black box including raw materials and products
Removal of n-butanol from water by activated carbon using Centrifugal Adsorption
Technology – CAT. Small particle sizes used, micrometer range.
Process functions:
* chemical / reaction
separation only
* separations
New, consider:
* process synthesis, project organisation
Not applied
* technical challenges
The application of centrifugal forces enables
* conservation laws
the use of small catalyst particles
* separate or combine functions
CAT. Smal particles – larger interfacial area – shorter diffusion pathway -> increased
efficiency. Settling of particles in water is difficult, can be improved by cenrifugal forces =
CAT
Hydrodynamic capacity is determined mainly by the particle diameterand the difference in
density and the speed of rotation. Two physical states possible:
- “free settling state” with very low solids hold up
- “fluidised state” – higher solids hold up. Preferred for intensive interphase contact.
Results
Demo of potential by pilot tests. Capacity 30-50 l/hr at 1000-1600 RPM
Increased flow and number of revolutions will decrease the NTU, caused by convective
transport. Backmixing reduces efficiency.
Industrial scale sedimentation centrifuge (capacity 20, 50 m3/hr) efficiency 98-99+ %
Overall: Low space requirements, short contact times, low adsorbent inventory
Related info
Summary
Keywords/essentials: Removal of diluted components from large aqueous streams
CAT - Centrifugal Adsorption Technique. Smal particles – larger interfacial area – shorter
diffusion pathway -> increased efficiency. Settling of particles in water is difficult, can be
improved by centrifugal forces
Results: prove of technology, low space requirement, short contact times and efficient use of
adsorbent
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 11
No
5
author-title
C.J. Cummings, G. Quarderer, D. Tirtowidjojo – Polymer devo
& pelletization in a rotating packed bed
Proceedings 3rd International Conference on PI, 1999, p 147
The Dow Chemical Company, USA
ref.
organisation
Process objectives
Improve polymer devolatalization by a combination of a rotating packed bed and a centrifugal
pelletizer
Existing / start situation
Removal of polymer monomer is usually done by flash devolatilization, residual level
monomer 200-500 ppm. Steam devolatilization reaches lower values, but is an expensive
process, energy intensive, side reactions can occur.
Process overall, as black box including raw materials and products
Rotating Packed Bed – RPB, Polystyrene devo system, capacity 90 and 450 kg/hr. Residual
concentration of monomer say 140 ppm.
Process functions:
* chemical / reaction
no reaction
* separations
Process parts:
- Feed system – extruder
- Devo and cutter: centrifugal force pushes the polymer through a rotating packing and a
circumferential set of die holes in the rotor. Countercurrent N2 flow applied. After being
extruded from the rotor, the polymer strands are cut into pellets as the rotor rotates past a
slowly moving, continuous blade.
- Product recovery system, provisions to apply heating, N2 purge and vacuum
New, consider:
* process synthesis, project organisation
not applied
* technical challenges
* conservation laws
* separate or combine functions
RPB devo “Accelerator” – modified baker Perkins G-force centrifugal pelletizers:
- Smaller physical size
- Lower capital investement
- A more energy efficient operation
- No potential for side reactions
Results
see above
Related info
Summary
RPB devo performance:
- Smaller physical size
- Lower capital investement
- A more energy efficient operation
- No potential for side reactions
RPB devo “Accelerator” – modified baker Perkins G-force centrifugal pelletizers. Contains
packing, dies, cutter. Provided with external heater and N2 purge
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 12
No
6
author-title
G.J. (Jan) Harmsen, A.P. Hinderink – We want less:
intensification by process synthesis methods
Proceedings 3rd International Conference on PI, 1999, p 23
Shell International Chemicals, SRTC, Amsterdam
ref.
organisation
Process objectives
Synthesis of a new chemical process with considerable lower fixed and variable costs, and less
energy requirement than the existing process
For PI: carry out as much as possible process tasks (functions) in as least as possible pieces of
equipment.
Existing / start situation
Not given
Process overall, as black box including raw materials and products
No information is given about chemistry and unit operations of the process studied
Process functions:
* chemical / reaction
* separations
Both part of the process designed
New, consider:
* process synthesis, project organisation
Carried out bij team of Shell and PDC using PROSYN. Time period: three months. Total costs
around US$ 200,000. Financial support from Novem.
The project starts at the highest level of PI, i.e., it starts with all the distinct process tasks to be
carried out in one piece of equipment. If the level of PI turns out to result in a more expensive
process, the intensification level is reduced, i.e. fewer tasks are combined.
Using the PROSYN module expert systems for reaction engineering suitable reactor-types are
indicated and directions for optimal operating conditions are given. For separation issues
modules for the most important unit operations are available.
PROSYN can be used for the conceptual design of new processes and the redesign of existing
processes. Advices given are cost driven.
Targets were set at the start of the project.
* technical challenges
Included in expert system
* conservation laws
Probably systematically applied
* separate or combine functions
Part of expert system
Results
New process concept involves a new reactor configuration, which combines reaction (to a
great extent), heat exchange and component separation in one piece of equipment
New process requires 40% less capital and operation costs, energy minus 20%, compared to
existing process.
Related info
Shell report to Novem
AIChE Symposium Series 323, Vol 96 (2000), p 364-366
Summary
Highly set targets on mass and energy savings and by applying heuristic process synthesis
methods and tools in combination with process simulation and process evaluation tools with a
devoted multi-discipline team has proved to be successful. New process requires 40% less
capital and operation costs, energy minus 20%, compared to existing process.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 13
No
7
author-title
C. Zheng, K. Guo, Y Song, X. Zhou, D. Ai – Industrial practice of
HYGRAVITEC in water deaeration
Proceedings 2nd International Conference on PI, 1997, p 273
Beijing University of Chemical Technology, P R China
ref.
organisation
Process objectives
Deaeration of water used for second recovery of oil and for boiler feed water to oxygen
content less than thermal methods, required < 50 ppb.
Existing / start situation
Vacuum desorption in packed tower. Oxygen from inlet 6 to 14 ppm to 500 to 1000 ppb.
Chemical agent added: to < 50 ppb or by using a 2nd vacuum tower.
Process overall, as black box including raw materials and products
Oxygen from inlet 6 to 14 ppm to 7 ppb
Process functions:
* chemical / reaction
no reaction
* separations
specific separation only
New, consider:
* process synthesis, project organisation
not applied
* technical challenges
* conservation laws
* separate or combine functions
Technology highgee deaeration, industrial capacity 50, 100 and 10 ton/hr water capacity.
Experimental work only. No fundamental approach or modelling
Results
Vacuum tower and higrav compared --> higrav preferred, certainly for off-shore application.
Less capital and space, low oxygen concentration, increased power (about factor two)
Related info
Summary
Application of higrav centrifugal field to deaerate water.
New application of recently developed technology.
Less capital and space, low oxygen concentration, increased power (about factor two)
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 14
No
8
author-title
F. Guo, Y. Zhao, J. Gui, K. Guo, J. Chen, C. Zheng – Effect of
inner packing support on liquid controlled mass transfer process
in rotating packed beds
Proceedings 4th International Conference on PI, 2001 p 107
Beijing University of Chemical Technology, P R China
ref.
organisation
Process objectives
Examine effect of packing inner support on on effectiveness of deaeration of water in a
rotating packed bed, nitrogen stripping applied
Existing / start situation
Conventional: vacuum desorption in packed bed, using chemicals.
Rotating packed bed, OD 350 mm, ID 250, axial length of wire mesh packing100mm.
Rotating speed 100 – 1200 RPM
Process overall, as black box including raw materials and products
Liquid capacity 0.5 – 2 m3/hr, gas flow 1-5 m3/hr.
Process functions:
* chemical / reaction
no reaction
* separations
New, consider:
* process synthesis, project organisation
not reported
* technical challenges
* conservation laws
* separate or combine functions
New is determination of effect of free area of inner packing support on efficiency of mass
transfer
Note: No information about packing outer support
Results
- Maximum NTU (about 0.3) for about 10% free area. Strong decrease towards 2.5% free
area, slow decrease towards 80% free area.
- Strong increase of NTU (times 2) for 100 to 400 RPM
Related info
Summary
- Specific technology examined and effectiviness proven
- No industrial or process application given, no scale up given
- Looks like that large gas flow is nitrogen and that may hamper application by cost reasons
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 15
No
9
author-title
ref.
D. Trent, D. Tirtowidjojo, G. Quaderer - Reactive stripping in a
rotating packed bed for the production of hypochlorous acid
D. Trent, D. Tirtowidjojo - Commercial operation of a rotating
packed bed (RPB) and other applications of RPB technology
Proceedings 3rd International Conference on PI 1999 p 217, 4th
International Conference on PI, 2001 p 11
The Dow Chemical Company, USA
organisation
Process objectives
In order to improve a chemical process, replacement of chlorine by low-chlorides
hypochlorous acid was desired. HOCl production technology had to be improved
Existing / start situation
A possible production of HOCL: Stripping of HOCl from the brine produced from reaction of
chlorine and aqueous caustic soda. Challenges: fast kinetics of desired reaction, low vapor
pressure of HOCl, and undesired decomposition reaction.
Several disadvantages for existing process, see p 219: solid salt product, energy inefficiency
of evaporation, condensation and the temperature swings for both, high gas recycle, high
pressures needed for spray atomization of expensive 50% NaOH, part of process near lower
explosion limit of Cl2O.
Yields reported: 65-80% improved at Dow lab test to 75-80%
Spray distillation process and absorption of HOCl in water. A large gas to liquid ratio, coupled
with the need for low gas velocities for entrainment minimization in the desorption, requires
large diameter equipment and, therefore, high capital costs.
Process overall, as black box including raw materials and products
Process overall yield of RPB process: 90%
Process functions:
* chemical / reaction
see p 218, p 219. First reaction is fast: NaOH + Cl2 --> HOCl(L) + NaCl
Basically two reactions:
2 NaCl + Cl2 --> NaOCl + H2O
NaOCl + Cl2 --> 2 HOCl + NaCl
Cl2 is absorbed into the aqueous caustic, liquid side mass transfer limited
HOCl and NaOCl are in equilibrium. Low pH is needed to form HOCl, at high pH stable
NaOCl is formed.
Secondly: 2 HOCl + OCl- --> OCl3- + 2 HCl. Decomposition of HOCl to CLO3- in the
presence of OCl-, is max at pH=7.4, a point that must be traversed as NaOH reacts with
Cl2 to produce HOCl.
HOCl can desorp from the L to the G phase, gas phase resistance is rate limiting
Next: gas phase decomposition of HOCl to CL2O (equilibrium). Required: low
concentration of HOCl.
HOCl in the vapor phase is stable (desired product) below the lower explosive limit of
about 23 mol% as Cl2O
* separations
Effective stripping can only be done at low pH when HOCl is dominant. Gaseous HOCl to
be absorbed in water in a separate column.
New, consider:
* process synthesis, project organisation
not applied
* technical challenges
* conservation laws
* separate or combine functions
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 16
Required:
- Quickly move through the maximum decomposition pH zone, to reduce CLO3- formation
- Maximizing the rate of stripping HOCl to the vapor phase, to reduce CLO3- formation
- Minimizing the rate of decomposition to Cl2O
RPB – rotating packed bed, an idea of George Quaderer. Not a result of systematic approach ?
PRB uses centrifugal force to move liquids through a porous packing, while gas moves
countercurrently.
Characteristics:
- low residence time, time scale adequate for reaction and mass transfer
- high mass transfer rate
- mechanical design
- scale up criteria
- known commercialization only in China
- from mass transfer limited to rate transfer limited in RPB
Process variables examined for maximum recovery of HOCl, pilot plant scale. Reviewed but
qualitative info about mechamism only.
After pilot tests scale-up to production plant, which is in operation for a few years now.
Results
For HOCl formation and desorption:
- HOCl yield for gauze packing about 90% independent of G-force and packing area
- Yields +10% and lower gas rates (less than half) compared to conventional process.
- Economic attractive
- Much smaller and less expensive equipment
RPB can also be applied for absorption of HOCl in water.
Related info
Summary
The production of low-chlorides HOCl solution has been enhanced by the use of a rotating
packed bed (RPB) gas/liquid contactor for stripping of HOCl from sodium chloride brine. The
RPB allows a size reduction in process equipment, but also provided improved process
performance with higher HOCl yields while using lower volumes of stripping gas.
The development of the HOCl process using the RPB and its scale-up was given.
The second contribution focus is on the successful operation of the process plant.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 17
ROTATING PACKED BED
Liquid
Feed
Seal
Outlet gas
Inlet gas
Seal
Rotating
Bed
Liquid
Discharge
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 18
No
10
author-title
ref.
Cees Kooijman - Liquid phase hydrogenation: an energy saving
alternative
2nd Dutch PI Symposium 10 October 2000
PIN NL meeting 14 April 2000
Akzo Nobel Central Research B.V., Arnhem
organisation
Process objectives
Improved process for hydrogenation of organic compound.
Combine low energy consumption and small amounts of byproducts = intensified process
Existing / start situation
Gas phase hydrogenation in fixed bed reactor containing noble metal catalyst. Fast reaction /
small reactor, short residence time give very little byproducts, <0.1%. Reasonable operation
pressure.
Energy consumption is high 500GJ/kton product – total reactor feed to be evaporated. Excess
H2 gas circulation by blowers, heat exchangers – maintenance
Liquid phase hydrogenation. No heat needed, simple – less maintenace. But conventional
trickle bed: large reactors, large amounts of catalyst and higher pressure. Long residence time
gives byproducts, 5%.
Absorption of sparingly soluble H2 is rate limiting step, mass transfer resistance, catalyst is
only partially wetted. Apparent reaction rate 1/8 of Langmuir-Hinselwood kinetics.--> better
wetting needed.
Process overall, as black box including raw materials and products
Hydrogenation of an organic component. Component is not given.
Process functions:
* chemical / reaction
Langmuir-Hinselwood kinetics determined in batch --> mass transfer resistance in Trickle
Bed Reactor
Vary Temp, Pressure and flow in TBR: Improved mass transfer, can reduce size of
conventional trickle bed to one fourth of conventional liquid phase hydrogenatio TBR
* separations
Not subject of study
New, consider:
* process synthesis, project organisation
Not applied, at least not documented
* technical challenges
Determine mass transfer and kinetics.
Apply knowledge of mechanism kinetics –
mass transfer to create efficient reactor system.
Lab test results verified to industrial scale.
* conservation laws
* separate or combine functions
Results
Byproduct reduced from 5% to <0.1%
Less energy consumption, savings new TBR vs. gas phase process: 500GJ/kton endproduct
are 80%
Basics – kinetics, mass transfer, flows/loads examined for Trickle Bed Reactor liquid-phase
Vary Temp, Pressure and flow in TBR: Improved mass transfer, can reduce size of
conventional trickle bed to one fourth of conventional liquid phase hydrogenation TBR.
Related info
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 19
Summary
From gas phase to liquid phase hydrogenation
Improved understanding of transfer mechanism in Trickle Bed Reactor --> smaller reactor,
less byproducts and small energy consumption
New Liquid Hydrogenation
H2
Feed
H2
Feed
H2, HX
Product
Product
Reaction rate
O
O
O
O
Kinetic experiments in batch reactor
± Mass transfer resistance is eliminated
± constant H2 pressure
H2
RX + H2 ---> RH + HX
R
Kinetics
R = k r .C RX .C H 2
Comparison kinetic reaction rate constant kr with results from
conventional trickle bed reactor (TBR)
kr = 8 kTBR,app
H2
: Mass transfer resistance in TBR !
kL. a
R
Mass transfer
Kinetics
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 20
No
11
author-title
F.W. Hesselink - Unrestricted application of PI
ref.
2nd Dutch PI Symposium 10 October 2000
PIN NL meeting November 1999
Lyondell Chemie Nederland, Ltd, Rotterdam
organisation
Process objectives
Increase energy efficiency by 30% for plant in Botlek (several processes)
Existing / start situation
Plants operated up to 30 years
Process overall, as black box including raw materials and products
No specific data given
Process functions:
* chemical / reaction
* separations
Both systems present in the processes examined
New, consider:
* process synthesis, project organisation
Not specific process synthesis applied
* technical challenges
* conservation laws
* separate or combine functions
Project organisation: Efficiency reviews of process technology by external contractor
Highlight process improvement opportunities by not being restricted by intimate knowledge of
the process or by history, by applying new technology, by not being corrected by Lyondell.
Financial support was given by Novem.
Results
After a four months the project resulted in a few dozen ideas/proposals. They were ranked on
the basis of impact, development, applicability (now, grassroot plant, long term development).
Two specific proposals to be worked out in detail in a next phase of the project:
- Alternative for MTBE process, reducing the number of units to a minimum. To be
considered when additional production capacity is needed
- Improved reaction-separation, reaction from gas phase to liquid phase, enhance separation
of butanes and recovery of H2 by membranes
General: project leaded to awareness and review of opportunities for new technologies, such
as membranes, HEX, reactive distillation, combination of units.
External experts can facilitate to reconsider process technology.
In a phase 2 of the project several options are worked out more in detail.
Related info
Summary
see Results
How reviews were done is not given.
Focus on energy and new technology e.g. membrane application.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 21
No
12
author-title
H.C. Rijkens - Membrane developments for natural gas
conditioning
2nd Dutch PI Symposium 10 October 2000
Shell Global Solutions, SRTC, Amsterdam
ref.
organisation
Process objectives
Dehydration of natural gas by membranes instead of by absorption sytems
Existing / start situation
Absorption of H2O and CO2 by solvent e.g glycol-water. Two towers ++ needed.
Process overall, as black box including raw materials and products
Removal of H2O and CO2 from natural gas
Process functions:
* chemical / reaction
* separations
separations only
Application of membranes, + sweep gas in countercurrent system
New, consider:
* process synthesis, project organisation
Not documented
* technical challenges
Improve conventional separation by
* conservation laws
application of new technology, see figures
* separate or combine functions
Membrane selection and application:
1. Line up: sweep by natural gas + permeate gas used for electricity production. Several line
up configurations tested
2. Second technology – Absorbing liquid on other side of membrane
3. CO2 and H2S removal
Results
Better separations with new membrane technology and new line up
Membrane technology. Advantages: passive – no moving parts, low operation intervention,
capacity and quality can be incrementally added, limited pressure drop. Lower investment.
Disadvantage: methane co-permeation
See picture below
Applied in several process locations
Related info
C.E. Klamer, presentation at PIN NL 17 December 1998
Summary
see Results above
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 22
Gas separation
e.g. dehydration of natural gas
high pressure (80 bara)
wet natural
gas feed
dry product
gas
Membrane
water vapour
permeate
low pressure (2 bara with sweep)
hydrocarbon gas
sweep gas
(or vacuum)
water vapour
Gas Dehydration
•
Removing water to very low concentrations (e.g. 99%
removal possible)
•
Very high membrane selectivity, resulting in typical
methane co-permeations of 0.5% of gas flow
•
Separate sweep is required (or vacuum) to transport
water away from membrane
Sweep
Feed
preheat
Membrane
Product
Filtration
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 23
No
13
author-title
K. Tjeenk Willink – Twister supersonic gas conditioning process
2nd Dutch PI Symposium 10 October 2000
ref.
organisation Twister, www.twisterBV.com
Process objectives
Separating water and condensates from natural gas, at reduced capital costs
Existing / start situation
Absorption of H2O and CO2 by solvent e.g glycol-water. Two towers ++ needed.
Process overall, as black box including raw materials and products
Lower dewpoint for natural gas by removal of water through adiabatic expansion
Process functions:
* chemical / reaction
No chemical reaction involved
* separations
New separation technology, see below
New, consider:
* process synthesis, project organisation
Not documented
* technical challenges
* conservation laws
* separate or combine functions
Gas is expanded adiabatically in a nozzle. E.g. Temperature drops from inlet 30ºC to – 50 ºC,
causes condensation of water and heavier hydrocarbons, separation of water etc. droplets by
highgee swirl initiated by a wing, recovery of pressure using a diffusor. See picture.
Fundamental flowstudies have been carried out also to extend application to new areas.
Results
Succesfull applications for feeds that have moderate hydrocarbon and water dewpoint
requirements.
Twister isentropic efficiency about 90%, so Twister is more efficient than a Joule Thomson
valve and a Turbo-expander
Lower costs and less space required compared to conventional absorption separation
Related info
see similar process function: H.C. Rijkens – Membrane developments for natural gas
conditioning, 2nd Dutch PI Symposium 10 October 2000
Summary
New drying / separation technology under development
Twister technology development is focussed on markets for:
- Gas dehydration (water dew point)
- Hydrocarbon dew point
- C5+ recovery
Potential application to other chemical processes
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 24
Twister Supersonic Separator
How it works
Dry Gas
Saturated Gas
Supersonic Wing (Mach 1-3)
Throat (Mach 1)
Liquid / Gas Separation
Liquids
Typical inlet
conditions:
Typical mid Twister
conditions:
Typical outlet
conditions:
100 bar, 25 degC
30 bar, -45 degC
70 bar, 15 degC
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 25
No
14
author-title
G.J. (Jan) Harmsen - Multi-functional reactors
ref.
2nd Dutch PI Symposium 10 October 2000
Chem. Eng. Sci. Vol. 54, no 10, 1541
Shell International Chemicals, SRTC, Amsterdam
organisation
Process objectives
Combining reaction and other process functions in one apparatus is a way of achieving
process intensification, increased efficiency and cost reduction
Existing / start situation
Conventional reactor technology
Process overall, as black box including raw materials and products
See cases below
Process functions:
* chemical / reaction
* separations
Reactions and separations combined
New, consider:
* process synthesis, project organisation
Not applied initially, done later on
Past trends: Experience, increased modelling, scale up. Started for the three cases several
decades ago.
Currrent trends – more multifunctional reactors: reduce energy, pollution, direct reduction
of byproducts / waste, application of process synthesis tools and modelling tools
* technical challenges
* conservation laws
* separate or combine functions
Three development and applications to processes have been reported:
1. Reactive distillation – to avoid conversion of formed product into unwanted component.
Reaction of an organic chlorine compound with an aqueous caustic solution in a distillation
column. Combined functions: dissolution of alkaline, reaction, separation of product from
reaction mixture through evaporation into the gas phase. Operation has been improved by
modelling.
2. Precipitative/evaporative reactor – combined functions: mixing, reaction, solvent separation
(evaporation) from reaction mixture, salt separation (precipitation) from reaction mixture, heat
exchange. Developed from bench scale studies to process application. Reduction of byproduct
and crystal size distribution supported by modelling.
3. Liquid-Liquid extraction reactor – combined functions: L/L – alkaline transfer to reaction
phase, reaction, salt extraction to aqueous phase.
Results
Smaller, more efficient reaction-separator systems; reduction of byproducts formed
Related info
F. Dautzenberg, Multifunctional reactors, Chemical Engineering Science 56 (2001) 252-267
and presented at PIN NL meeting May 2002
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 26
Summary
Smaller, more efficient reactor-separator systems have been developed. This is illustrated by
three multi-phase multi-functional reactors.
From trials to systematic designs, using modelling and process synthesis.
Development of multi-functional reactors is stimulated by requirements for: safety, reduction
of energy consumption and waste production, and cost reduction.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 27
No
15
author-title
Z. Xu – Converting batch processes into continuous processes,
development of the Helix reactor
Proceedings 4th Int. Conference on PI, 2001, p 117
TNO MEP, project for Laporte Performance Chemicals
ref.
organisation
Process objectives
Increase production capacity and
- reduction of production costs
- decrease of energy consumption
- reduction of chemical waste
- improvement of product quality
Existing / start situation
Production of glycidyl ethers by reaction of alcohol and chloroalkylepoxide
O
O
/
\
catalyst
/ \
R-OH + CH2 – CH – R’ – Cl ------> R – O - R’ – CH – CH2
- in a multi-product batch process, two steps: synthesis and distillation
- reaction liquid phase in batch reactor, kinetics are known
- reaction highly exothermic, heat limits feed rate of raw material, one component in excess
- separation in batch distillation columns
Byproducts formed by side and consecutive reactions – reduces selectivity and increases
energy usage of distillation columns
Process overall, as black box including raw materials and products
Capacity, prices, not given
Process functions:
* chemical / reaction
* separations
New, consider:
* process synthesis, project organisation
No details given
* technical challenges
Helix and conversion from batch to continuous
* conservation laws
* separate or combine functions
- Consider application of continuous process using plug flow Helix reactor with improved
heat exchange
- Stoichiometric feed of components, mixed in a static mixer before the reactor
- Helix reactor – two twisted tubes, helix format creates strong internal circulation / radial
mixing and promotes heat transfer at low Re. Confirmed by CFD simulations.
- The exothermic reaction can now be carried out up to the kinetic limits, increased safety
- Tested at pilot scale, reactor tube length 3 m, stoichiometric feed of reactants
Results
- Proof of technology at small pilot scale in laboratory – continuously operation of Helix
reactor
- Less separation and recycle due to stoichiometric feed
- Increased selectivity, waste – 15%
- Energy – 30%
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 28
Summary
Existing process analyzed for potential improvements, from batch to continuous operation
Concept of new heat exchanger-reactor
Combination of challenge for process improvement and new technology
Reduction of byproducts formed and energy consumption
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 29
No
16
author-title
ref.
organisation
Jan Moreau – Energy saving Heat Exchanger Reactor at DSM
NPT procestechnologie, mei/juni 2003, p 32
DSM Research
Also presented at PIN NL meeting 1 May 2001 by
Corné van Zantvoort
Process objectives
Develop multi purpose polymerisation reactor
Considered for capicity expansion
Existing / start situation
Multistep synthesis. Especially the first step – fast exothermic reactions in semi-batch process:
- poor temperature control has negative effect on product quality and safety (runaway)
- long dosing times and long reaction times
- multipurpose facilities means no optimum for specific production
- two cases - details of reaction kinetics are known and not known
Process overall, as black box including raw materials and products
No additional process data given. Most probably polymer production
Process functions:
* chemical / reaction
= Main process issue
* separations
Removal of byproducts by ceramic membranes
First examined - what are critical process parameters for the reactions:
- heat removal for strongly exothermic reactions
- controlled and energy efficient byproduct removal
- optimisation of mass transfer in highly viscous media
New, consider:
* process synthesis, project organisation
See point 2
* technical challenges
See existing /start situation
* conservation laws for mass, heat, momentum etc.
* separate or combine functions
New developments based on critical parameters given above:
1. New heat exchanger reactor – small volume + large heat exchange area, (semi-)continous
with superior temperature control, mixing elements in loop, used in front of stirred vessels
which complete reaction with additional feeds. Loop reactor 80% conversion for a
residence time of several minutes in stead of hours for the batch process.
2. Multidisciplinary project team, multidisciplinary project approach
3. Systematic analysis of existing process, determination of kinetic parameters in laboratory
4. Spinning disc reactor has been examined for completion step of chemical reaction. Issues:
heat transfer, degassing
5. Ceramic membranes for removal of lights by water flux, have to be improved
Project has been supported by Novem
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 30
Results
For loop reactor system – start up, normal operation, shut down, set point and grade changes:
- batch time reduction. Reaction to completion, from some hours reaction time to a few
minutes. Consequently reactor volume can be reduced substantially
- consistent/reproducible quality
- inherently safer and controllable process
- first step to a fully continuous process?
- energy reduction, heating of the reactor content is no longer needed
- lower investment
Spinning disc reactor: additional research is needed
Ceramic membranes: severe process conditions (e.g. temperature) hamper application
Related info
Summary
Existing technology (continuos loop reactor) systematically developed for application in
polymerisation process. Improved performance found.
Spinning disc reactor: proof of technology
Ceremic membrane separation examined, not feasible yet
Flowsheet
sample
Raw materials
Post
Reactor
sample
Loop
reactor
Double jacket
static mixers
Recirculation pump
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 31
No
17
author-title
ref.
B.M.M.(Bram) Delfos
Process 2000+, a study towards a new process for the production
of linoleum
Forbo report for Novem, public version, 2002
Presented in PN NL meeting May 2002
Forbo Linoleum, Krommenie, The Netherlands
organisation
Process objectives
Increase yields, reduce energy consumption,emissions and costs, improve reproducibility of
operation and labor conditions
Long term: be able to double production capacity
Development of a new process for process steps: esterification and oxidation
Existing / start situation
Process steps for linoleum production:
Esterification->oxidation->mixing->calandering->drying->finishing
Characteristics of batch process: long process time, week quality control, large energy
consumption, operation based on experience and not on chemical and physical basics, large
cleaning effort of batch reactors
Several raw materials: linseed oil, tall oil, natural resins, wood sawn, cork, limestone,
pigments. Tall oil esters are prepared before the oxidation step to reduce time needed for
oxidation. Linseed oil - similar products are formed. Oxidation is done by using air feed;
exhaust gas outlet is the result, emission.
Process overall, as black box including raw materials and products
The project is focussed on:
linseed oil, tall oil,
esterification
resins, catalyst
e
linseed oil cement
+ oxidation
First step is an esterification of tall oil. A mixture of tall oil ester, linseed oil, resins is
sequentially sent to the oxidation reactor. Air is used as an oxidant. Four phases in the
oxidation process require different conditions:
1. Induction step. Peak heating (up to 130ºC) to remove anti-oxidants which hamper the
oxidation. Hot water is fed through the double wall of the reactor vessel
2. Peroxide formation, at lower temperature (85ºC). Exothermic reaction. Now cooling water
trough the double wall
3. Peroxide breakdown. Addition of the catalyst creates active groups (radicals)
4. Polymerisation. By reaction of radicals, moderate exothermic reaction. Depends on
amount of unsaturated compounds, reaction time etc.
Total residence time 16-30 hrs. Then the viscous mass is discharged to curing tanks, where
additional oxidation takes place for about 10 days.
Process functions:
* chemical / reaction
= esterification and oxidation
* separations
no part of the study
New, consider:
* process synthesis, project organisation
* technical challenges
* conservation laws for mass, heat, momentum etc.
* separate or combine functions
Investigation and development of activities leading to functional requirements for
improvement of production process. Done in cooperation with external expert of PDC and
Akzo Nobel Engineering and R&D, July 1999 to September 2000. Activites:
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 32
-
Collection of process data for existing process including operator experience
Literature search for chemical and physical properties of all components and kinetics +
heat effects of reactions. Done in cooperation with Akzo Nobel
- Design of a new production process using expert system PROSYN
- Determination of mass and heat balances of existing process
- Basic design of new process; design of new reactors, heat exchangers, control and
safeguarding
- Tests on pilot plant scale, located at Akzo Nobel
Akzo Nobel resin facilities and experience were used to determine polymerisation degree and
molecular weight distributions and heat effects. Mathematical modelling of the reactions was
started. The effect of process variables was examined at the process test unit at Forbo. PDC
expertise by PROSYN was used to design the reactor configuration. Different reactor
configurations were examined. Process mass and heat balances were simulated using Aspen.
Interaction of experts in the team was well organised.
New process set up:
Continuously operated stirred tank reactors in series, air countercurrently to process flows.
Process functions:
1. Linseed oil activation. In the first CSTR: linseed oil preoxidation, autocatalitically at
relative lower temperature by the concentrations in the first reactor. Antioxidants are
deactivated.
2. Oxidation. Mixing of tall oil, activated linseed oil creates a medium wherein components
will be oxidized. The polymerisation starts also.
3. Polymerisation step. Less oxidation and increased polymerisation
A pilot unit (1:10000 scale, reactor volume 2.5 liter) was build and tested during a month.
Reaction progress was followed by IR/GPC-analysis. The product was converted to linoleum.
A small scale production unit (scale 1:100) was sequentially build and operated for four
months at Forbo facilities. The product was converted into linoleum. properties were
examined.
The effects of process variables on steady states and product quality were determined. E.g.
Oxygen consumption per mass determines the conversion and is an important control
parameter. Stabilization of the continuous process requires about a week time.
Project has been supported by Novem funding.
Results
Determination of basics of reaction steps and pilot tests has led to a continuous process which
yields a good product, less waste, requires less catalyst (-50%), less energy (-15%) and
pollutes less.
Report to Novem states that concept will probably be used when increased capacity is needed
in the future. Company report 2002 informs that the new technology has been implemented,
reduction of raw materials has been realised, energy consumption reduced by 7.5%
Summary
Process analysis, cooperation of expertise of consultants and other industries, determination of
basic process properties and the use of pilot facilities has enabled a new systematic design of
process steps in a rather conventional type of industry, the linoleum precursor production.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 33
No
18
author-title
M.A. Linthwaite, S.W. Colley
Process Intensification in practice
Proceedings 4th Int. Conference on PI, 2001, p 135
Kvaerner Process Technology Limited, UK
ref.
organisation
Process objectives
Demonstration of application of PI reactor technologies to chemical processes
Existing / start situation
Process examples taken for:
- Esterification process, reaction of an alcohol with an acid to produce ester and water, an
equilibrium reaction. Commercially low conversion and susequent separation or excess of
alcohol to achieve conversion of acid. Catalyst, usually sulphonic acids are neutralised
with inorganic basis after completion of the reaction
- Hydrogenation of aldehydes to form alcohols – reduction of exotherms
- Reaction of ethylene oxide and an alcohol to glycol ethers – reduction of byproduct
formation
Process overall, BB including RM and products
Three new reactor types commercialised that include several of PI’s key elements –
concatenation of equipment, significantly reduced equipment size, intensifcation of reaction
rates
Process functions:
* chemical / reaction
* separations
Both considered in examples below
New, consider:
* process synthesis, project organisation
No information given
* technical challenges
Influence equilibrium reaction – CCR,
reduce exotherm or endotherm by recycle
of products – LRR
* conservation laws for mass, heat, momentum Not applied systematically
* separate or combine functions
Combine reaction and separation – CCR
Three new types of reactors:
Counter Current Reactor – CCR. Application of reactive distillation.
Liquid Recycle Reactor – LRR
Advanced Loop Reactor – ALR
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 34
Results
Counter Current Reactor – CCR
Applied for esterification of maleic anhydride to dialkyl maleates, and for fatty acids to fatty
acid esters. Water removal is needed in order to allow the the reaction to proceed to high
conversion. Reactor column contains a number of chambers containing solid catalyst. Liquid
(acid) flows from top to bottom. Alcohol vapor flows from bottom to top and absorbs water
formed.
Positive effects: water removal shifts equilibrium, solid catalyst enhances reaction rate, no
catalyst removal from process streams. Enhanced reaction rates reduce the size of the reactor.
Product: high purity ester, 99.5% so no post treatment is needed. Low alcohol to acid ratio
(circa 2:1), reducing the need to purify large amounts of wet alcohols.
Liquid Recycle Reactor – LRR
Reduce of exotherm or endotherm by the use of the product as a recycle and as a diluent.
Commercially applied for the hydrogenation of aldehydes to form alcohols. Dilution by
recycle allows the reaction to be carried out at 150-180ºC, increasing the reaction rate and
aiding recovery of the heat of reaction. Amount of byproducts is significantly reduced by
reduction of hot spots, which reduces the size of down-stream processing.
Advanced Loop Reactor – ALR
E.g applied for exothermic reaction of ethylene oxide and an alcohol to glycol ethers. The
distribution of the glycol ether chain length can be influenced by the mixing at the point of the
ethylene oxide feed. An efficient mixing reduces localised in-homogeneity or temperature
peak and narrows the chain length distribution. A heat exchanger is part of the loop system.
ALR is an extension of loop reactor technology.
Related info
Summary
Efficient application of specific reactor technology to overcome a number of drawbacks for
existing processes
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 35
No
19
author-title
ref.
organisation
S. Puhakka, H.Haario, I. Turunen, K. Ruutu, T. Kämä, J.
Koskinen – Intensification of polymerisation process for
production of polyaniline
Proceedings 4th Int. Conference on PI, 2001, p 239
Lappeenranta University of Technology, Panipol Ltd, Fortum Oil and
Gas Ltd, Neste Engineering Ltd, Finland
Process objectives
Application of tubular reactor for polymerisation of aniline to polyaniline. Create basis to
improve batchwise stirred tank reactor technology.
Existing / start situation
Polymerisation in batchwise operated stirred tank reactors. Problems to produce a polymer
with controlled uniform quality, control of temperature and mixing is required.
In polyaniline the nitrogen atoms of monomer units are bonded to the para-carbon in the
benzene ring of the next monomer unit. Kinetic correlations are available, very exothermic
reaction. Details of mechanism are unknown.
Process overall, BB including RM and products
Raw material: aniline and ammonium persulphate as oxidiser
Process functions:
* chemical / reaction
Exothermic polymerisation
* separations
Not studied
Challenges of tubular reactor:
- Static mixing results in more uniform concentration and temperature distributions
compared to a stirred tank reactor. Better product quality can be expected
- Several feed points are possible. When kinetics etc. are known, this can be used to adjust
selectivity and yield
- With tightly controlled conditions, narrow distributions of polymer properties can be
obtained. Change of operation conditions can be used to produce different grades
New, consider:
* process synthesis, project organisation
* technical challenges
* conservation laws for mass, heat, momentum etc.
* separate or combine functions
No information about project approach and application of systematic techniques for PI or
process synthesis. Focus on reactor technology, separation not considered.
Use of tubular reactor (length 3m, diam 10 mm) with static mixers and a cooling jacket.
Semibatchwise operation: step 1 is circulation monomer over reactor, step 2 is continuos
addition of persulphate at constant rate to total amount, step 3 is completion of polymerisation.
Results of reactor simulation model (under development) shows conversion profiles.
No information given about capacity of system. Scale up possible by using lager static mixer
reactors provided with cooling coils.
Additional tests in large scale equipment are needed.
Results
Molecular weight distribution of polymer from conventional stirred tank is slightly broader
and the average molecular weight is slightly higher. In the tubular reactor, these polymer
properties can be controlled by adjusting temperature and feed ratio’s.
Test facilities subject for improvement.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 36
Summary
Application of static mixer reactor for aniline polymerisation. Initial tests show opportunities
for control of product quality.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 37
No
20
author-title
ref.
W.J.W. (Wridzer) Bakker
Pervaporation using ceramic membranes – from concept to
commercial implementation
a.o. Presented at PIN NL meeting 18 October 2001 and at NMG
meeting 7 February 2001
Patent WO 99/59711, 25 November 1999
Akzo Nobel Research, Arnhem, NL
organisation
Process objectives
Business Unit need for robust, efficient tool for water removal from “difficult liquid mixtures”
to increase production efficiency and flexibility and to meet environmental requirements
Existing / start situation
Separation of water from liquid mixtures
Process overall, BB including RM and products
Pervaporation and reaction application:
- breaking azeotropes
- removal of water from organics
- recovery of organics from water
Process functions:
* chemical / reaction
Separation first, reaction included
* separations
Water removal by pressure difference over membrane
New:
* process synthesis, project organisation
Role of expertise group: - supply of required system boundaries and testing, - “Push”
potential commercial suppliers towards commercialization of new technology
Cooperation with other business units Akzo Nobel, ECN, Sulzer, Univ. of Aachen, IFP,
Novem separation group GUTS.
* technical challenges
Ceramic membranes are under development. Akzo Nobel project took over more than 4 yrs,
from single tube, bench scale (7 tubes) to 1 m2 membrane area demo unit. Subjects: basic
principles, flow studies (CFD), construction details.
Strong combinations:
- distillation/pervaporation - dewatering of organics, removal of organics from wastewater
and organics.
- reaction and pervaporation – placed in loop around reactor, replacing condensation system
* conservation laws for mass, heat, momentum etc.
* separate or combine functions
Results
Successful application of ceramic membranes for “simple” dewatering applications. Both
pervaporation and permeation.
Developed from single tube, to bench scale 0.1 m2, to demo unit 1 m2 built by Sulzer
Chemtech and ECN. For T < 180ºC and P < 10 bar. Development to be continued to 100 m2.
Fouling and membrane stability are a main point of concern.
Applications to processes are given in the patent.
Related info
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 38
Summary
New separation technology - water removal by pervaporation through ceramic membarnes pushed by business and specific process requirements. Development in cooperation with other
partners from basis to production scale.
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 39
Pervaporation principle
Water vapor
Low pressure
Membrane
Liquid reaction
mixture
Dewatered
reaction mixture
Selective removal of one or more components from
a liquid with the aid of a membrane.
Typical process example
reaction-pervaporation
vacuum pump
Condenser
membrane
e.g.
H2O
Column
Entrainer
e.g. xylene
Reactor
cold trap
New
Reactor
Old
Application of PI in the process industries, review and analysis of 20 cases - Henk van den Berg 2003
Pagina 3. 40