We do this by changing the scale
of the mixing structure from one that is
distributive to one that is dispersive. This is achieved with what we
call the "U" type Ultra Mixer.
The basic mixing elements of this static
mixer can be changed from a coarse to a
fine scale of structure to concentrate
initially on distribution and finally on
dispersion of the additive.
VISCOSITY
AND PRESSURE DROP CONSIDERATIONS
| Most
polymeric materials are shear
sensitive. That is to say, their
viscosity is dependent on the
shear rate to which they are
exposed. Usually an increased
shear rate produces a lowering of
viscosity and is referred to as
shear thinning. Viscosity versus
shear rate data is usually
provided by the polymer
manufacturer in the form of a
graph on log/log paper. We list
below the shear rate and pressure
drop formula for each of the
devices we have described and
others together with the units
involved. Main pipe inside
diameter = D inches
Main product flow rate = Q gpm
Shear rate = g
sec-1
Viscosity = m cP
Pressure drop = dP psi
Axial length = L inches
Additive fraction = F
Number of mixing elements = n
|
|
| Device |
A/t
Value |
Shear
rate |
Pressure
drop |
Comments |
| Open
pipe |
---------- |
39.2Q/D3 |
22.73x10-6Qm L/D4 |
Hagen-Poiseuille
Equation |
| Helix |
np |
96.0Q/D3 |
205x10-6Qm n/D3 |
Helix
L/D ratio = 1.5:1 |
|
KOMAX
SYSTEMS, INC.
INTRODUCES
A
NEW STATIC MIXER SYSTEM
FOR
HIGH VISCOSITY PRODUCTS
(U.S. Patent 5,484,203)
-
A Single Injection Point
allows pressurized clearing action from the
additive pump if needed. The built in check
valve prevents back flow of polymer into the
additive supply.
-
The PARAFLO
Injector
distributes additive across
the inlet of the ULTRA mixer.
It is less than one pipe diameter in length
and has a low pressure drop.
-
The ULTRA
Mixer
generates multiple interstices with a
uniform spatial distribution to give 100%
utilization of the mixer volume and
superior additive dispersion
with low pressure drop.
|
 |
| Device |
A/t
Value |
Shear
rate |
Pressure
drop |
Comments |
| L/H
unit |
8/p2
F |
215Q/D3 |
5.9x10-4Qm /D3 |
Each
hole dia. = 0.45D |
| H/L
unit |
3.6/F |
81.7Q/Dt2 |
22.1Qm L/Dt3 |
Where
annulus dia.= 2D/3 |
| SIDD |
288/p2 F |
593Q/D3 |
12.6x10-4
Qm
/D3 |
Each
hole dia. = 0.3D |
| PARAFLO |
8pN/F |
Contact factory for
shear rate and pressure drop
calculations. |
|
