Disc stack centrifuges

FLOTTWEG DISC STACK
CENTRIFUGES
Innovative liquid-solid separation
Separation principles
Mixtures of immiscible liquids,
Fw. In a viscous fluid, the par-
This equation shows the
such as water, oil and solids,
ticles reach a terminal velocity
significant parameters which
can be separated by gravity if
also known as the settling or
influence the terminal velocity:
the components have different
buoyant velocity depending
densities. Solid or “spherical”
on the density of the particle
Particle diameter d:
particles (such as oil droplets
– larger or smaller than the
The terminal velocity increases
in water or water droplets in oil)
viscous fluid. With assumed
with the square of the particle
are influenced by three differ-
laminar flow the resulting
diameter. Large particle diam-
ent forces (Fig.1). The gravity
terminal velocity is given with
eters result in higher terminal
Fg interacts with the buoyant
the Stokes Law (Fig. 2).
velocity.
force Fa and the frictional force
Fa
␳FI
Fw
d
d2⋅ (Δρ)
Vg =
⋅g
18 ⋅ η
␳s
Fg
Particle influenced by three different forces
(Fig.1)
Terminal velocity Vg (Fig.2)
Difference in density ⌬␳:
It is important to regard the dis-
Increasing difference in the
tance between the particle and
density of particle and solid
the bottom/surface to estimate
results in higher terminal
the time of the sedimentation/
velocity.
flotation. The separation is finished when all of the particles
Dynamic viscosity ␩:
have sedimented (trub residues
Decreasing dynamic viscosity
in juice production) or floated
in the fluid results in higher
(oil droplets in water).
terminal velocity.
2
The separation process
in the disc stack centrifuge
Imagine a continuous system
This can be avoided by inser-
Liquid/liquid separation such
area. The centrifugal force of
for solid/liquid separation at
ting plates to reduce the dis-
as the separation of water
a centrifuge (up to 16000 x g)
a high flow rate. If the feeding
tance to the bottom (h Æ h1).
and oil, works on the same
strongly increases the effect of
speed is high, some particles
More clarification area is pro-
principles (Fig. 6).
this clarifying area.
will not reach the bottom and
vided (Fig. 4). This will work
will flow away with the liquid.
until the system clogs.
The disc stack of the separator
The geometric surface of the
divides the product stream into
discs (clarifying area) and the
By using inclined plates the
thin layers. The separation itself
centrifugal force result in the
solids will slide to the tank
happens in the space between
“equivalent clarifying area”.
bottom (Fig. 5).
two discs. A high number of
This factor shows the
discs result in a large clarifying
capability of a separator.
The separation process is
incomplete (Fig.3)
h
W2
h1
(Fig.3)
(Fig.4)
(Fig.5)
(Fig.6)
Clarification
(Fig.7)
Separation
d2⋅ (Δρ)
Vg =
⋅ rϖ 2
18 ⋅ η
(Fig.8)
3
Disc stack centrifuges in
process technology
Self-cleaning disc stack cen-
than for e. g. in a decanter.
There is a wide range for the
trifuges for liquid/solid separa-
Hence disc stack centrifuges
application of disc stack cen-
tion are essential in many tech-
are predestined for processes
trifuges. You find them in every
nical processes. The rotation
which require high separation
branch of industry – like the
speed of disc stack centrifuges
efficiency or the separation of
food and beverage, animal and
is much higher than most other
micro particles. Even mixtures
vegetable fats and oils, chem-
centrifuges in industry. The
of liquid phases with very small
istry, pharmacy and biotech-
centrifugal force in a disc stack
difference in density can be
nology, mineral oil products,
bowl is apparently stronger
separated.
energy production, and environmental protection.
Oil
Water
Oil
Water
Water
Solids
Solids
Solids
Sedimentation in a test-tube – clarification, purification, concentration
Separators are essentially
liquid phase with lower density,
Hence to these basic pro-
designed for three basic pro-
(e.g. water droplets from min-
cess operations FLOTTWEG
cess operations:
eral oil). The separation of solids
SEPARATORS are designed
at the same time is possible.
as Clarifiers, Purifiers and
Clarification
Concentrator variants.
Finely dispersed particles are
Concentration
separated from a fluid (e.g.
Separation of a liquid with low-
trub solids in juice)
er density from a continuous
liquid phase with high density,
4
Purification
(e.g. essential oil from water).
Separation of a liquid with high-
The separation of solids at the
er density from a continuous
same time is possible.
Advantages of self cleaning
disc stack centrifuges
Compared to other centri-
Compact design, small foot-
Liquid-liquid separation of
Easy to operate and control
fuges and filter systems, self
print, yet high flow rates
fluids with minor difference in
through continuous and auto-
cleaning disc stack centrifu-
Separation of finely dispersed
density
matic operation
ges offer several advantages:
particles
Closed design that prevents
No filter cloth, additives, or
odor emission or contamination
flocculants necessary
of product and environment
(optional)
FLOTTWEG SEPARATORS in the field
Typical applications*
Beverage/food
Chemical/pharmaceutical/
tion broth, solvents, chemical
Industry/mineral oil
Fruit juice, vegetable juice,
biotechnical
waste water
Slop oil/waste oil treatment
essential oil, wine/must, pectin,
Whey clarification, process
tea, coffee
water in the starch industry,
Oils and fats
algae (food additives), indus-
Land animal fat and fish oil,
trial biotechnology/fermenta-
vegetable oil, algae (biofuels),
in combination with the
olive oil, biodiesel
FLOTTWEG TRICANTER®
* more applications available
upon request
5
Functional principle of a self cleaning
disc stack centrifuge
The product to be separated
impeller (5) to be discharged.
Bowl
enters the inside of the bowl
Depending on the process, the
The bowl of a self-cleaning
through a stationary inlet pipe
liquid can be discharged under
disc stack centrifuge consists
(1) into the distributor (2). The
pressure or unpressurized.
of a bowl bottom (6) includ-
separation takes place in the
A distinction is drawn between
ing the hydraulic discharge
disc stack (3). The product
a clarifier and a purifier version
system and the bowl top. The
flow is divided into multiple
with a single or double impeller. solid discharge (9) is opened
thin layers by the disk stack
Separated solids are packed
and closed by vertical sliding
and a large surface area is
in the solids chamber (4) and
of the piston (7) and controlled
created. From the disk stack,
discharged periodically.
by the bowl valves (8). Using
the clarified liquid flows to the
a hydraulic system in the bowl
Feed
Centrate
5
1
2
3
4
6
9
7
8
closing water
opening water
Cross section of a FLOTTWEG SEPARATOR
(clarifier version)
bottom, the separated
Disc stack
tor through the inlet pipe (1). A
solids are discharged at
The disc stack (3) consists of
specially-designed distributor
full speed.
the discs and the distributor.
ensures the smooth accelera-
The purifier and concentrator
tion of the product. The impact
The hydraulic system of the
versions are equipped with
of sheer forces on the particles
FLOTTWEG AC centrifuges
additional separation discs (10).
has to be avoided. This would
enables exactly reproducible
The product is introduced
lead to emulsification and
partial discharges as well as
to the center of the distribu-
therefore be counterproductive
total discharges in any combination.
6
FLOTTWEG SEPARATOR bowl
for the separation process.
Liquid discharge
There are three options for
Passing the distributor through
The separated liquids leave the
the purifier and concentrator
ged by a single impeller (5).
holes at the bottom, the prod-
disc stack centrifuge through
version:
The light phase is discharged
uct enters the disc stack.
the liquid discharge. The
– Both separated liquids are
unpressurized and leaves
Through the rising channels,
design varies depending on
discharged by means of a
through a stationary regulat-
the product is fed into the
whether it is a clarifier, purifier
double impeller (11).
ing ring.
space between the discs. An
or concentrator version.
– The heavy phase is dischar-
– The light phase is discharged
by a single impeller. The heavy
additional separation disc on
top of the disc stack (purifier
Using a clarifier version, the
phase is discharged unpres-
and concentrator) ensures the
liquid is discharged under pres-
surized and leaves through a
separated or concentrated
sure via a stationary impeller.
stationary regulating ring.
liquid to flow into the corresponding collection chamber.
Feed
discharge
light
liquid
discharge heavy
liquid
11
10
1
3
closing water
opening water
Cross section of a FLOTTWEG SEPARATOR
(concentrator version)
Disc stack
Tri-clamp connection with screw joint
Drive
enabling a smooth acceleration
Materials of construction
steel or duplex alloys. The
The required drive power is
and limiting the inrush current.
All product-wetted parts are
sealing materials are made
transmitted directly to the bowl
Furthermore, there is the pos-
made of stainless Cr-Ni-Steel.
of perbunan (NBR) and poly-
shaft using a standard three-
sibility to vary the bowl speed.
Depending on the require-
amide. Other materials such as
ments, the components of the
PEEK, Viton (FKM) and EPDM
bowl are made of stainless
are available.
phase AC motor with frequency Compared with other drive
drive control via a V-ripped
systems, the FLOTTWEG drive
or flat belt. The motor is con-
offers lower maintenance and
trolled by a frequency drive
increased efficiency.
7
Lubrication
Hydrohermetic
hermetic seal consists of a sta-
The bearings are lubricated
The hydrohermetic seal option
tionary disc above the impeller.
using an internal oil lubrication
enables hermetic feed of the
The disc is dipped into the fluid
system. Oil level and flow are
product (clarifier version). Oxy-
sealing the product from the
controlled by the control system
gen pick-up, foaming, or gas
environment. The system is
(AC1500, 2000, 2500). An oil
leakage is avoided. The hydro-
quite similar to a siphon.
pump provides appropriate proportioning of the lubricating oil.
Cross section FLOTTWEG SEPARATOR
CIP
Explosion proof
FLOTTWEG SEPARATORS are
All FLOTTWEG SEPARATORS
designed according to require-
are in compliance with the
ments of “hygienic design”. They
regulations of 94/9/EG (ATEX95).
can easily be integrated into an
They are suit-
automatic CIP-system.
able for use in
explosion hazardous areas.
8
Inert gas purge unit
vapors mixed with aerial oxy-
to be gastight to prevent the
cally used in the chemical,
Inert gas purge units are nec-
gen generate an explosive mix-
exit of vapors into the atmo-
pharmaceutical, or the mineral
essary for the production of
ture, the risk of explosion has
sphere as well as to avoid the
oil industry. It is used for all
products whose vapors may
to be eliminated by replacing
entry of air into the system.
systems which process highly
contaminate the atmosphere
air with an inert gas. Usually
Inert gas is injected into sev-
flammable organic solvents or
or to prevent contact of the
this operation is done using
eral parts of the centrifuge in
hazardous volatile components.
product with the atmosphere
pure nitrogen. Centrifuges and
order to provide optimal purg-
Inert gas units prevent the oxi-
(oxidation). If centrifuges are
system parts used for the pro-
ing and inert gas blanketing
dation of products in the food
used to process media whose
cessing of such materials have
inside the centrifuge.
and beverage industry as well
Inert gas purge units are typi-
as in the edible oil industry.
FLOTTWEG purge gas control unit
Centrifuge controls
FLOTTWEG touch control
– Motor protectors and ramp-
All centrifuge functions and
up control system using
components are monitored
frequency drive
and operated by a programmable logic controller (PLC).
– Timer for automatic solid
discharge
– Solid discharge controlled by
turbidimeter (option)
– All necessary touch and
operating controls
– Control of all components of
the disc stack centrifuge and
(optional) secondary systems
The control cabinet includes:
9
Technical data*
Type
AC1000
Volume
Solids chamber
Separator motor
Dimensions
(Lenght × Width × Hight)
AC1500
AC2000
AC2500
4 liter
14 liter
25 liter
58 liter
(1.1 US gallon)
(3.7 US gallon)
(6.6 US gallon)
(15.3 US gallon)
1,5 liter
7 liter
11,5 liter
22,5 liter
(0.4 US gallon)
(1.8 US gallon)
(3.0 US gallon)
(5.9 US gallon)
5,5 kW
18,5 kW
37 kW
55 kW
(7.4 hp)
(24.8 hp)
(49.6 hp)
(73.8 hp)
1100 × 600 ×
1500 × 1000 ×
2000 × 1100 ×
2.100 × 1300 ×
1000 (mm)
1700 (mm)
2000 (mm)
2100 (mm)
43 × 24 × 39 (inch) 59 × 39 × 67 (inch) 79 × 43 × 79 (inch) 83 × 51 × 83 (inch)
Gross weight
Hydraulic capacity
390 kg
1600 kg
2900 kg
3750 kg
(860 lbs)
(3527 lbs)
(6393 lbs)
(8267 lbs)
10.000 l/h
20.000 l/h
45.000 l/h
85.000 l/h
(44 US gpm)
(88 US gpm)
(198 US gpm)
(374 US gpm)
* The listed figures are guidelines only
FLOTTWEG SEPARATOR AC2000 gastight version in explosion-proof design
10
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worldwide
Application-based project
Experienced and reliable
FLOTTWEG products are
planning, high-quality
service engineers from our
designed and manufactured
manufacturing and professional
customer service department
in GERMANY!
after-sales service are
are ready to respond quickly
prerequisites for customer
to reduce down time. The
ISO certification
satisfaction.
FLOTTWEG service group
FLOTTWEG is ISO 9001
is also available to perform
certified and manufactures its
preventive maintenance.
products in compliance with all
current technical standards.
FLOTTWEG services include:
Competent advice on separa-
Selection and specification of
Design and construction of
Preventive maintenance
tion processes
equipment
complete process systems
Customer training
Tests at the Flottweg
Customer-tailored automation/
Installation, commissioning,
laboratory and test center
control systems and process
maintenance, repair, and spare
Pilot tests on-site
integration
parts service worldwide.
11
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On our homepage www.flottweg.
in Vilsbiburg, Germany, near
com under contact/service you
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PR-0004 ZK - 10 09/09
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