Devolatilization
In the field of polymer devolatilization,
NFM/Welding Engineers holds an impressive array of
experience and accomplishments that include:
- patented multi-stage venting
- rear venting
- counter-current and co-current stripping
New products include:
- streamlined preconcentration systems that maximize
output and quality of solution polymers
- large-scale processing techniques for extrusion
drying of elastomer solutions.
Over 25 years ago, NFM/Welding Engineers was the first
manufacturer to commercialize twin screw devolatilization
of reactor solutions with 6" lines for devolatilizing
acrylic and styrenc polymers from 50% solids. We are
currently en ganged in the creation of a new generation
of devolatilizing equipment.
The Advantages of Twin Screw
Extrusion
- Capable of Handling Many Viscosities:
Twin screw extruders
excel in positively conveying high viscosity
fluids. By contrast, other equipment may have
torque limitations or insufficient conveying
capabilities, resulting in material degradation
and long changeover between product grades.
- Contained and Recoverable Waste
Streams:
The design flexibility
of NFM/WE extruders allows environmental considerations
to be addressed as part of the process.
- Short Residence Time:
Our twin screw design
has the shortest residence time of any devolatilization
device (less than three minutes, typical).
Changeovers are faster, thermal history is
minimized, and product is less likely to be
degraded.
- Efficient Heat Transfer:
Twin screw extruders
can increase temperature by controlled shearing
of the polymer solution. Other devices rely
on surface renewal, pressure, and conductive
heat transfer for devolatization.
- Narrow Residence Time Distribution:
Gel information,
discolored product, or broad molecular weight
distributions are reduced by the design of
the twin screw, small volume and positive conveying
characteristics.
- Efficient Surface Renewal:
For highly concentrated
polymer solutions (less than 1% solvent), twin
screw extruders are ideal for renewing surfaces
through the use of multi-flighted screw elements
and high screw speeds.
|
SUCCESSFULLY
DEVOLATILIZED POLYMERS
|
Styrenic Materials: |
|
SAN
ABS
SMA
SB Copolymers
|
SIS, SEBS & SBS
Block Copolymers
|
|
Engineering Thermoplastics:
|
|
Polyarylate
|
PEI
|
|
Synthetic Rubber:
|
|
SBR
EPDM
|
PBd
Silicones
|
|
Other Materials:
|
|
PMMA
PE
|
PP
Expoxies
|
|
 |
The Advantages of
an NFM/WE Twin Screw Extruder
- Large Free Volume Contains
Foaming Melts:
NFM/WE's counter-rotating,
non-intermeshing screw design has the largest
free volume capabilities of any twin screw
extruder manufacturer for containing foaming
melts (typical of 30%-50% solvent concentrations).
This extra free volume also means that we can
provide longer residence time under each vent
reducing tendencies for vent flow and overall
better performance and operability.
- Large Vents Up to 6 D Long
by 1 D Wide:
Our extruder design
offers longer, wider vents allowing vapor velocity
to be lowered and the entrainment of the polymer
to be reduced accordingly. Larger vents also
mean higher vapor removal capability, due to
low velocity when removing large amounts of
solvent and extra residence time under vacuum
removal of the final parts per million of solvent.
- Downward Screw Rotation Resists
Vent Fouling/Flow:
Our design allows
the barrel to be open for a vent over a full
diameter directly over the center of the screws
(and wider in some cases). The screws' rotation
acts to pull polymer down in the vents, thus
resisting vent fouling or flow.
Process Parameters
- Viscosity Range:
5,000-5,000,000
centipoise @ 100 reciprocal seconds, 20-80
Mooney Viscosity.
- Free Solids Content:
30% and higher to
the extruder.
- Temperature Control:
Temperature is controlled
by screw design, screw speed, and barrel temperature
regulation. The use of water stripping may
also provide some cooling capacity.
|
|
| NFM/WE Machine Capacities |
|
ITEM |
Nominal Diameter
Nominal Inches
|
Capacity
lbs/hr @ 50% (kg/hr @ 50%) Solids Feed
|
Capacity
lbs/hr @ 90% (kg/hr @ 90%) Solids Feed
|
Rated Horsepower
|
|
Laboratory
|
0.80
|
15 (7)
|
30 (14)
|
10
|
|
Pilot
|
1.18
|
50 (23)
|
100 (45)
|
25
|
|
Semi-Works
|
2.00
|
200 (91)
|
400 (182) |
100
|
|
Commercial
|
2.80
|
400 (182)
|
800 (367)
|
150
|
|
|
3.5
|
800 (367) |
1,600 (727)
|
250
|
|
|
4.5
|
1,500 (682) |
3,000 (1,364)
|
500
|
|
|
6
|
4,000 (1,818) |
8,000 (3,636)
|
1,000
|
|
|
8
|
8,000 (3,636)
|
15,000 (6818) |
2,000
|
|
|
10 |
16,000 (7,273) |
30,000 (13,636) |
4,0000 |
Specifications are subject to
change without notice.
|
Contact
Us
- For more information on devolatilization or
any other processes made possible by an NFM/Welding
Engineers' system, please contact us. We would
be glad to provide additional data or technical
support at any stage of your project.
|
 |
..top of page.. |
