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How a technology can be continuously updated: the EP(D)M experience Gabriele Gatti- versalis Elastomer Process and Technology Manager
Bangkok, November 15th, 2013
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versalis EPM/EP(D)M technology - basics
Versalis technology is based on the slurry process (suspension of rubber crumbs in C3 mix).
A Ziegler-Natta polymerization of ethylene and propylene (copolymer, EPM) is performed in a single continuous stirred reactor. The addition of the third monomer (ENB) allows the production of terpolymers (EP(D)M) with a termonomer max content of 9-10% w/w.
Heat is removed by vaporization of part of the boiling C3 which is then compressed, condensed and recycled back to the reactor.
C3, C2, third monomer recycled and C3, catalytic system, modifier are separately routed to the reactor.
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versalis EP(D)M technology - products
EPM grades are entirely saturated and therefore require vulcanization by organic peroxides.
EP(D)M grades have a residual unsaturation in the side chains and can therefore be cured with sulfur
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Case History - EP(D)M processes – process comparison
EP(D)M are produced using basically three main processes:
Slurry process with Ziegler-Natta catalyst system (versalis)
Wide product mix, mainly for HMW for TPV applications. Line size: 40-50 kta
Not proprietary catalyst. Process available for licensing.
Variable cost: lower than Ziegler-Natta solution
Solution process with Ziegler-Natta catalyst system
Wide product mix, mainly for low ashes requirements. Line size: 40-50 kta
Not proprietary catalyst.
Variable cost: higher than slurry phase
Solution process with Metallocene catalyst system
Few molecular types, narrow MWD, very sensitive to oxidative poisons. Line size: 80-100 kta
Proprietary catalyst.
Variable cost: the lowest compared with the other processes
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versalis EP(D)M technology – block diagram
Monomer(s) purification
Monomers
Finished product (25 kg bales)
Chemicals and catalyst
Polymerization Stripping Finishing Ingredients and catalyst preparation
Plant facilities
Versalis assets – EP(D)M
EPM/EPDM (3 lines) versalis Ferrara, Italy Operation
EPM/EPDM (1 line) versalis Ferrara, Italy Construction
EPM/EPDM (2 lines) JV, Far East Engineering
EPM/EPDM (2 lines) Licensed, South East Asia Engineering
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versalis EP(D)M technology – optimization project
The slurry process is a quite mature technology, with proven advantages in terms of energy consumption compared with the standard solvent process, but some years ago it required a deep rejuvenation.
In 2010 versalis decided to invest time and resources on this process, as the EPM/EPDM market was strongly increasing. The developing team has been commissioned to achieve the following objectives:
increase Plant capacity, focusing on reactor’s throughput and control,
reduce reactor’s fouling and increase service factor,
allow production of extremely soft or hard products,
debottleneck all the Plant’s sections,
update operations, chemicals, technologies, process control with the new opportunities available on the market.
A case history
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Case History: versalis EPM/EP(D)M Reactor and Stripping
Reactor and Steam Strippers are the core sections of the Plant:
Slurry to strippers
Modifier
Propilene, Propane, Ethylene, Catalyst
Rubber crumbs to finishing
Slurry, extender oil
C2, C3 to purification
Steam, additives
Water + ENB to regeneration
REACTOR STEAM STRIPPING
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Case history – First step: advanced process control (APC) to increase quality and capacity
Every optimization can only start after complete knowledge of the real capability of the polymerization technology. In the EP(D)M process, polymerization is complex due to high number of raw materials / chemicals, fed to reactor in different ratios and due to the kinetic model itself.
For this reason it was necessary to develop a system to help Plant’s personnel to anticipate and avoid the fluctuations in product quality due to different reaction conditions.
Thanks to a huge database of all the most important process parameters and the connection with the Lab process control procedure, the APC developed by versalis is able to predict the product properties and allows to be faster to identify the trends and to anticipate the appropriate settings.
APC has increased the first quality production and reduced the time required for every change of campaign, thus enabling Plant to increase service factor and annual capacity.
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Case history – Second step: EPDM reactor optimization and scale-up to increase throughput and quality
A second step was dedicated to the mechanical modification of the EP(D)M reactor that had to be adapted to new products (more mixing required, less fouling accepted) and new capacities (scale-up of the reactor, better service factor)
Analysis of the process variables
Step 2.1: analysis of process variables and present geometry
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Case history – Second step: EPDM reactor optimization and scale-up to increase throughput and quality
Step 2.2: Analysis of the reactor’s sections prone to fouling
Step 2.3: Identification of the products whose properties could be enhanced by a reactor’s modification
CO034
CO038CO043
CO054
CO058 CO059
TER4028
TER4033
TER4038TER4039
TER4044
TER4047
TER4049
TER9046
TER4334
TER4436
TER4437
TER4535
TER6148
TER6235
TER6537
15.0
17.0
19.0
21.0
23.0
25.0
27.0
50 55 60 65 70 75
To
tal S
olid
[%
]
Bound C2 [%]
Impeller rear side
Area close to the agitator shaft
Liquid/vapour intephase
Inner surface of the vessel
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Case history – Second step: EPDM reactor optimization and scale-up to increase throughput and quality
Step 2.4: Definition of the scale-up requirements
New reactor capacity
New design rate
Enhanced time between cleaning
These results shall be achieved working on:
Type of agitation
Monomers feed (rate, geometry)
Cooling capacity
Study has been carried out using 3D models and CFD
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Example of Integrated mixing CFD study – bulk mixing
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Example of Micromixing CFD study
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Case history – third step: EP(D)M stripping and finishing updating
The achieved increase of hourly and yearly capacity required actions on the section of the Plant where reliability and throughput weren’t in line with the new production targets.
Steam strippers have been studied in order to disengagement of the light monomers and the diffusion of the third monomer @ the new target throughput reducing the steam consumption;
Finishing configuration has been deeply modified in order to prevent out-of-spec and mechanical failure which could affect the required smooth run;
Finishing fumes have been selectively collected in order to have the right abatement system for each stream, from the simple water scrubbing to the sophisticated activated carbon treatment to entrap the smelly compounds.
The new EP(D)M lines are sized for an expected capacity of +30% (yearly) of the present ones
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Ongoing …
The pilot Plants at Ferrara, Italy, are working on new products and optimizations
versalis shall increase the product portfolio by introducing a fourth monomer and the relevant new grades.
New developments in catalysis are going to be introduced, to reduce chemicals consumption and enhance products’ quality.
Stay tuned!