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Society of Petroleum Engineers I
SPE 48870
Comparison
of Plate Separator,
Centrifuge and Hydrocyclone
Wim M.G.T. van den Broek, SPE, Delft University of Technology,
Mark J. van der Zande, SPE, Delfi University of Technology r ‘“
Copyright
1998, Society of Petroleum
Engineers,
Inc.
This paper was prepared for presentation
at the 1998 SPE
Exhibition in China held in Beijing, China, 2-6 November 1998.
International
Conference
Robert Plat, State Oil Company
Surinam N. V., SPE, and
viz. the gravity force or the centril%gal force.
The three mentioned techniques are the subject of this
paper: they are described and analysed, and typical data on
e.g. volume, flow-rate and performance are given. Next the
results of some laboratory experiments on plate separation and
are presented.
Subsequently
the
three
centrifhgation
techniques are compared, and possibilities for performance
enhancement are discussed. We will start, however, with some
remarks on other separation techniques.
and
This paper was selected for presentation by an SPE Program Committee following review of
information contained in an abstract submitted by the author(s). Contents of the paper, aa
presented, have not been reviewed by the Society of Petroleum Engineers and are subject to
correction by the author(s). The material, as presented,
does not necessarily
reflect any
pos!tion of the Society of Petroleum Engineers, its ofricers, or members. Papers presented at
SPE meetings are subject to publication review by Editorial Committees
of the Society of
Petroleum Engineers. Electronic reproduction, distribution, or stomge of any part of this paper
for commercial purposes without the written consent of the Society of Petroleum Engineers ia
prohibited, Permission to reproduce in print is restricted to an abstract of not more than 300
words;
illustrations
may
not be copied.
The
abstract
must
contain
conspicuous
acknowledgment
of where and by whom the paper was presented, Write Librarian, SPE, PO.
Box 833B36, Richardson, TX 75083-3B36, U.S.A., fax 01-972-952-S435.
Other De-Oiling Techniques
Plate separation, centrifugation and the use of hydrocyclones
are not the only techniques that are - or can be - used for deoiling of produced water. Others are:
Biological
degradation.
This
technique
has
two
disadvantages in connection with use in the oil industry, viz.
the relatively large amount of space needed for a separator
unit and the relatively large amount of time needed for the
breakdown of the oil products.
Filtration. Removal of oil by membrane filtration has been
practised in the past (Ref. 1). There are, however, maintenance
problems and, more important, only relatively small producedwater flow-rates can be handled.
Flotation. This technique has been, and still is, frequently
used for the de-oiling of produced water. The key difficulty of
this technique is the creation of favorable
circumstances for
separation, and in this respect there are few similarities
between, on the one hand, a flotation unit and, on the other
hand, a plate separator, centrifuge or hydrocyclone.
Stripping. This technique is used for the removal of
soluble oil components.
The occurring phenomena
differ
considerably from the ones taking place in a plate separator,
centrifuge or hydrocyclone.
Of the mentioned other de-oiling techniques two, viz.
biological degradation and filtration, seem to have too many
drawbacks for their effective use in the oil industry, and
therefore become uninteresting. The other two, flotation and
stripping, are and will remain important separation tools.
However, because the separation processes differ,much from
centrifuge
or
those
occurring
in a plate
separator,
hydrocyclone, filtration and stripping are not further treated or
discussed in this paper.
Abstract
Frequently
oil is produced
while, simultaneously,
large
amounts of water are produced
as well. Under these
circumstances it is important to have compact and efficient deoiling equipment at one’s disposal. After some remarks on
other de-oiling methods, the attention in this paper is focused
on three separation techniques: plate separation, centrifugation
and the use of hydrocyclones.
The working principles are
described
and subsequently
typical data on separation
efficiency,
geometry
of the separator
section, separator
volume and critical oil-droplet diameter are derived or given.
Analysis of these data shows, that the ranking with respect to
performance
of the three separator types is: centrifuge,
hydrocyclone, plate separator. In the last section of the paper
attention is given to some recent developments
concerning
centrifugation and the use of hydrocyclones.
Introduction
An important problem in the oil industry is the treatment of
produced water, especially
in the case of offshore oil
production
where space and floor area, needed for the
equipment,
are extremely
costly.
Increased
separation
production of water occurs when an oil field matures, and the
availability of efficient and cost-effective techniques partly
determines the period during which economic production is
possible. For the final de-oiling process several techniques are
available, of which plate separation, centrifhgation and the use
of hydrocyclones are important ones. Common characteristics
of these three techniques
are that only insoluble
oil
components
can be removed,
and that the prevailing
separation process is movement of the oil droplets with respect
to the continuous phase, water, as a result of an external force,
391
2
W\M M.G.T. VAN DEN BROEK, ROBERT PLAT, AND MARK J. VAN DER ZANDE
The Plate Separator
In the channel of a plate separator (see Fig. 1), oil droplets
flow from the inlet to the outlet with the same horizontal
velocity as the continuous phase, water. Due to the density
difference with water, they also have a vertical velocity. An
oil droplet is separated when, as a result of its vertical
velocity, it reaches the top of the channel and coalesces with
the other separated dropIets. The stationary vertical velocity,
Vz, can be found by equating the buoyancy force acting on a
droplet and the resistance-to-flow
force as defined in Stokes’
law (Ref. 2). The result is:
detailed analysis is given in Ref. 3. To the presented equations
we add the following notes:
Separator angle. In case the angle of the separator with the
horizontal is u instead of zero, a droplet has to travel a larger
distance to reach the upper side of the separator channel. To
calculate the critical oil-droplet diameter in this case, one has
to replace H by H/cosct.
ReynoIds number. Separation is only achieved in case the
flow in the separator channel is laminar. In practice separatorchannel heights of about 3-20 mm are encountered. For the
linear velocities this implies that the largest velocities which
can be permitted are some tens of cmls.
Velocity profile. The relation for the critical oil-droplet
diameter was derived under the assumption of a constant v,
(plug flow), while” iii practice the velocity- profile in the
channel is parabolic. It can be shown (Ref. 3) that the derived
equations are also valid in case the velocity profile is
parabolic.
Separator-channel
shape. To improve the removal of the
separated oil, the separator plates (and, consequently,
the
separator
channels)
of commercial
separators
are often
corrugated, see Fig. 2. Also for a corrugated channel the
presented equations remain applicable. It is noted, however,
that the maximum
allowable
Reynolds
number will be
somewhat lower than for flow in a straight channel.
To be able to compare a plate separator with a centrifuge
and a hydrocyclone,
we assume the following typical data:
length, width and height 2.00 m; channel height 5.0 mm; plate
thickness 1.0 w
no angle with the horizontal. Furthermore
we assume mat the maxigmm Reynolds number is 1000.
Using 1000 kg/m3, 100 kg/m3, 0.0010 Pas and 10 rnfsz for,
respectively,
the density of water, the density difference
between water and oil, the dynamic viscosity of water and the
acceleration of gravity, we find a maximum v, of 10.0 cmls.
This yields, at the maximum flow-rate of 0.333 m3/s, a critical
oil-droplet diameter of 67 pm. This DC-vaIue is unattractively
high, and in practice one would use a lower flow-rate so that a
lower DC can be achieved: e.g. D;s of 30, 35 and 40 ~m
correspond with flow-rates of, respectively, 0.067, 0.091 and
0.119 m3/s. In practice the lower limit of the critical oildroplet diameter is believed to be in the 20-30 pm range, see
Ref. 4.
ApgD2
‘z =
18/4
As the critical oil-droplet diameter,
diameter for which, for the corresponding
valid:
v,
H
—=—
v,
L
Combination
DC, we defiie the
vertical velocity, is
.
—.
of these two equations yields:
DC’ =
18Hpvx
ApgL
In case an oil droplet has a diameter DC then, in case its
starting position is at the bottom of the separator-channel
inlet,
it will arrive at the outlet precisely at the top, i.e. at the end of
the upper separation plate. For other starting positions it will
reach the upper separation plate earlier. All oil droplets with a
diameter larger than DC(these have a larger VJ are removed in
the channel. Consequently, for the removal efficiency of a
separator channel is valid:
q=lfor
D2D
c
The Centrifuge
The equations as presented for the plate separator are also
valid for the centrifuge, with the understanding
that the
acceleration of gravity, g, has to be replaced by the centrifugal
acceleration,
@zr. This yields for the critical oil-droplet
diameter:
Oil droplets with a diameter smaller than DC will only be
partly removed:
the removal
efficiency
decreases
with
decreasing diameter. For the efficiency in this case can be
derived:
~=
()
;
SPE 48870
2
18Hpvx
for
D<D
D,’
c
c
=
Ap(i)2rL
Also in this case the channel height, H, has to be corrected
when the channel orientation is not perpendicular
to the
Evidently q is equal to the efficiency of a separator unit,
which consists of a set of identical separator channels. A
392
SPE 48870
COMPARISON OF PLATE SEPARATOR, CENTRIFUGE AND HYDROCYCLONE
direction of the centrifugal
force (replacement
of H by
WCOSJ3).
In Fig. 3 the principle of the disc-stack centritige
as
manufactured
by Al fa-Laval is sketched. The separation
section consists of a stack of conical discs, with the distance
between the discs typically being of the order of 1 mm.
Separation only takes place in the outer section, where the
centrifugal
force is largest. An alternative
design for
separation was developed by Plat (Ref. 3) by replacing the
disc stack by a set of vertical plates. Fig. 4 depicts the general
idea, while Fig. 5 gives the four types of channels which were
investigated.
Also for the centrifuge we make some assumptions for the
typical dimensions: location of the separation section between
5.0 and 7.0 cm from the rotation axis; height of the separation
section 25 cm; distance between the separator platesldiscs 1.0
mm; angle 13 45°; rotation velocity 6000 rev.hnin. For the
water density, density difference between oil and water and
the viscosity of water we take the same data as for the plate
separator (see previous section). Using again a critical
Reynolds number of 1000, this yields an (average) maximum
water velocity of 0.50 rnls. This corresponds with a flow-rate
of 0.0236 m3/s, while the critical oil-droplet diameter in this
case can be calculated as 14 pm. Also here lower DJs can be
achieved by decreasing the flow-rate: e.g. DC’Sof 5, 6 and 8
pm correspond
with flow-rates of, respectively,
0.0031,
0.0045 and 0.0079 m’ls.
The critical oil-droplet diameter which can be achieved
with a centrifuge can be even lower than 5 pm. With the
configurations sketched in Fig. 5, De’s in the 2 ~m range have
been reached. It is believed, however, that much lower values
than this cannot be realized. To this is added that very low
values correspond with extremely low flow-rates, which can
make such a separation procedure unattractive and unpractical.
3
Flow-rate. For influx flow-rates of 0.0013 up to 0.0023
m3/s, the efficiency is constant (about 90 ‘%o), provided the
ratio between the flow-rates of overflow and influx is larger
than about 1 ‘%.. The absence of the influence of flow-rate is
somewhat surprising. Apparently the decrease in centrifugal
acceleration for decreasing flow-rate, which has a negative
effect on the efficiency, is compensated in this flow-rate range
by the increase in residence time in the cyclone, which has a
positive effect.
Oil-droplet size. There is a marked influence of the oildroplet size on the separator efficiency, For D,O-values of 55,,
40 and 35 pm the efficiency is relatively high, but this
decreases to about 70 Y. and about 50 % for D5Js of 25 pm
and 15 ~m, respectively. These figures are for relatively light
oiI; for heavier oil the efficiency is even lower. A possibility
to increase the efficiency is operating with two hydrocyclones
in series (tandem configuration).
Other parameters. The influence of other parameters which
were investigated by Young et al. were inlet oil concentration,
oil-water density difference, and geometrical parameters such
as overflow diameter, cone angle and feed size. A very
significant
effect was only measured
for the density
difference, of which an increase led to an increased cyclone
performance.
For comparison with a plate separator and a centrifuge we
list characteristic
data of the Colman-Thew
hydroclone:
maximum inner diameter 70 mm, length more than one metre,
typical flow-rate range ‘O.OO1O-O.OO3Om3/s and capable of
removing oil droplets of about 20 pm and larger.
Experiments on Plate Separation and Centrifugation
Experiments have been carried out to determine the separation
efficiencies of a plate separator and a centrifuge. Fig. 7 gives
the set-up for the testing of a plate separator. A similar set-up
was used for a centrifuge. The tap-water flow is divided into
two streams: the larger part flows in the direction of the
separator, while the smaller part is forced through a needle
valve, where oil is added to the water stream. Subsequently
this oil-water mixture is led into the main stream. The
turbulent conditions in the valve lead to dispersion of the oil.
Consequently, the influx of the separator consists of an oil-inwater dispersion. The oiI-dropIet-size
distribution
of this
dispersion can be varied by manipulating
the following
parameters: flow-rate in the bypass, pressure of the oil pump
and position of the needle-valve stem. With a particle size
analyser (Malvem, type 3600E) the droplet-size distributions
of influx and effluent can be measured, and from these data
the separation efficiency of the separator as a function of
droplet diameter can be derived. The oil used in the
experiments was Shell Omala 220.
Fig. 8 gives an exampIe of the results for a plate separator
with flat plates and a separator with corrugated plates. It can
be seen that there is no significant difference between the
results for flat plates and those for corrugated plates, and that
these results are in good agreement with the theoretical
prediction. We note that, for the laboratory experiments,
configurations were used with channel heights which were
The Hydrocyclone
In a hydrocyclone the centrifugal acceleration is the result of
the enforced, tangential entrance of the produced water into
the separator, see Fig. 6. The oil droplets will eventually be
concentrated in the centre, the core, of the cyclone and wilI
leave the device through the overflow. The water goes out at
the underflow. The processes in a hydrocyclone
are more
complex’ than those occurring in a centrifuge. Firstly the
acceleration and the influx flow-rate are coupled. A larger
influx velocity induces larger centrifugal forces, and this
means that the performance of the cyclone is influenced by
this flow-rate. Secondly the local acceleration is dependent on
the distance to the core centre and is also strongly influenced
by the geometry of the cyclone. Thirdly the separation process
is also influenced by the ratio between the overflow and influx
flow-rates.
The hydrocyclone for de-oiling of water was developed in
1980 by Colman and Thew (Refs. 5 and 6). For its
performance we base ourselves on an article by Young et al.
(Ref. 7), in which a hydrocyclone with a 35 mm radius, and
variants thereof, was tested. Important
results of this
investigation were the following:
393
4
WIM M.G.T. VAN DEN BROEK, ROBERT PLAT, AND MARK J. VAN DER ZANDE
larger and lengths which were shorter than one would use in
practice. This explains the fairly large critical diameter of
about 100 ~m. Fig. 9 gives an example of results achieved
with a centrifuge, for three flow-rates. Also here there is a
good agreement between the experimental
results and the
theoretical prediction.
possibilities to improve its performance.
Decrease of the
channel height leads to a decreasing D=. There is a limit,
however, to this height decrease because of the probability of
channel blockage. Moreover, for a constant separator volume
a channel-height decrease leads to more separator plates and,
hence, to a larger plate volume and a smaller net separator
volume. A point in favour of height decrease is that it allows a
higher maximum velocity v,, because the maximum Reynolds
which can be permitted is reached for a larger VX. Also
increase of the separator-channel
length leads to a decreasing
DC, but it is noted that the separator volume increases
proportionally,
so that this does not lead to a performance
enhancement in terms of flow-rate per unit volume, The last
way in which a better performance can be achieved is decrease
of the water viscosity. This can be realized by practicing
separation at a higher temperature, but this implies heating of
the produced-water
stream, which can be rather costly.
Consequently,
for the plate separator some performance
enhancement is possible, but this will be marginal with respect
to the best data given earlier in this paper.
For the centrihge we have already mentioned possibilities
for performance
enhancement.
These can be achieved by
introducing novel separator internals as sketched in Fig. 5
instead of using a stack of conical discs (Fig. 3). With respect
to channel height there is the possibility to realize smaller
heights than are possible with discs, although also here there is
a lower limit because of the probability of channel blockage
for very narrow channels. The largest advantage of the novel
internals, however, is the better way in which the produced
water is distributed over the charmek. For the conicaI discs the
water has to flow through a separate channel consisting of
holes in the discs, which leads to a non-uniform distribution:
the flow-rate in the lower channels will be higher than that in
the upper channels. This will have an unfavorable
effect on
the centrhige performance when the height of the separation
section becomes too large. A centrifuge provided with novel
internals does not have this drawback, thus the separation
section can be much larger. Therefore it is expected that a
centrifuge provided with novel internals can perform better,
and that a net separation volume can be achieved which is
substantially higher than that of a disc-stack centrifuge.
A recent development concerning hydrocyclone design is
work by Dirkzwager (Ref. 8) on an axial cyclone, in which the
spinning motion is not caused by the tangential influx, but by
an axial swirl element with vanes. The predictions on the
behaviour of this cyclone are based on calculations and
numerical simulations. The ultimate objective is to develop a
cyclone which is relatively small, has a high throughput, is
efficient and has a much lower pressure drop than a
conventional hydrocyclone
(of which the pressure drop is
typically of the order of 1-3 bar). Preliminary data about this
axial cyclone are: pressure drop about 0.4 bar for a flow-rate
of 0.0020 m3/s. Apart from investigating the Colman-Thew
hydrocyclone, Young et al. (Ref. 7) also adapted this device,
which led to an equal performance for higher flow-rates. They
also designed cyclones with a lower DC, but these can only be
used for relatively small flow-rates. We already mentioned the
Comparison of Plate Separator, Centrifuge and
Hydrocyclone
For the comparison between the three separators in question
we will consider three characteristics:
the critical droplet
diameter, the flow-rate and the separator volume.
Critical oil-droplet diameter. The separators do not have a
fixed critical droplet diameter, because this parameter is
influenced by e.g. oil-water density difference, separatorchannel dimensions and separator geometry. Furthermore is
valid, for plate separator and centrifuge, that this critical
diameter decreases with decreasing flow-rate, which will lead
in practice to choosing the flow-rate (the separator capacity) in
such a way that the resulting DC is acceptable. Nevertheless
one can speak of typical DC-ranges: about 30-40 pm for the
plate separator, about 5-10 pm for the centrifuge and about 20
pm for the hydrocyclone, to which is added that for all these
devices lower values are achievable.
Flow-rate. For typical flow-rates we list the values already
given earlier: about 0.07-0.30 m3/s for the plate separator,
about 0.003-0.020 m3/s for the centrifuge and about O.OOIO0.0030 m3/s for the hydrocyclone. These flow-rates are highest
for the plate separator, but this device is also by far the most
voluminous.
Separator volume. Taking into account extra volume,
because the total volume of a separator (or the space it is
taking in) is larger to much larger than the separation section
proper, the volumes of one plate separator, one centrifuge and
one hydrocyclone
as described
earlier can be roughly
estimated at about 15-20, about 0.02-0.03 and about 0.01-0.02
m3, respectively. Combination of these data with the total
flow-rate ranges as given above yields for the flow-rate per
unit volume 0.004-0.020, 0.10-1.00 and 0.05-0.30 s-’ for plate
separator,
centrifuge
and
hydrocyclone,
respectively.
Although these figures are only indicative, they show that with
respect to flow-rate per unit volume the centrifuge performs
better than the hydrocyclone, which in its turn is better than
the plate separator.
With respect to performance on both critical oil-droplet
diameter and ratio (flow-rate)/(separator
volume), the ranking
is centrifuge, hydrocyclone,
plate separator. In practice,
however, the hydrocyclone is more in use than the centrifuge.
This has to do with three circumstances: (i) in magy.cases the
better performance of the centrifuge with respect to DC is
unnecessary, (ii) the centrifuge needs electrical energy (which
a hydrocyclone does not need) to let it rotate with a high
rotation frequency and (iii) the centrifuge is a (much) more
expensive separation device than the hydrocyclone.
New Developments
Concerning
the plate
separator
there
are
a number
SPE 48870
of
394
SPE 48870
COMPARISON
OF PLATE SEPARATOR,
CENTRIFUGE
AND HYDROCYCLONE
5
~ = distance to the rotation aXk
Vx = average water velocity
v, = stationary vertical oil-droplet velocity
cz = angle between plate-separator channel and
horizontal
Y = angle between centrifuge channel and rotation axis
Ap = difference between the densities of water and oil
q = removal efficiency of a separator or separator
channel
P = dynamic viscosity of water
cu = angle velocity of the centrifuge
option to increase the efficiency of a cyclone by using two
cyclones in a tandem configuration. Consequently, there are a
number of possibilities to improve the performance
of a
hydrocyclone,
Apart from developments on equipment design there is
also an interesting development
concerning the production
process, viz. separation of oil from water not at the surface but
downhole, at the bottom of the well, see Kjos et al. (Ref. 9).
Because the available space in a borehole is very small, this
manner of separation can only be realized with a hydrocyclone
or a centrifuge. Up till now only hydrocyclones are used for
this production technique. Evidently the use of centrifuges is
considered
uneconomical.
Application
of this downhole
separation
technique
makes it attractive
to search for
separation devices which are even more compact than those
available now. Furthermore
we remark that, apparently,
efficient separation can be carried out with a hydrocyclone.
This means that, at the bottom of the well, the majority of the
oil droplets will be larger tian about 20 pm (being the order of
magnitude
of the critical - oil-droplet
diameter
of a
hydrocyclone). However, in practice also relatively small oil
droplets may be present in the borehole, as is predicted by
Janssen et al. (Ref. 10). Under these circumstances the use of a
hydrocyclone may be ineffective, and it would be a logical
step to consider the use of a centrifuge in these cases.
References
1. Op ten Oort, F.J., Etten, J.P., and Donders, R.S.: “Reduction of
Residual Oil Content in Produced Water at Offshore Gas
Production Platform P/6A”, paper SPE 20882 presented at the
1990 European Petroleum Conference, The Hague, Oct. 21-24.
2. Bird, R.B., Stewart, W.E., and Lightfoot, E.N.: “Transport
Phenomena”, John Wiley & Sons, New York, 1960.
3. Plat, R.: “Gravitational and Centrifugal Oil-Water Separators
with Plate Pack Internals”, PhD-thesis, Delft University of
Technology, 1994.
4. Van den Broek, W.M.G.T.: “Some theoretical aspects of deoiling of water by plate separation”, Delft Progress Report, VOI.
13(1 988/1 989), pp. 87-97.
5. Colman, D.A., and Thew, M.T.: “Hydrocyclones for Oil-Water
Separation”, paper presented at the International Conference on
Hydrocyclones, BHRA Fluid Engineering, Cambridge, 1980.
6. Colman, D.A., and Thew, M.T.: “Hydrocyclones to Give a
Highly Concentrated Sample of a Lighter Dispersed Phase”,
Conference on
paper presented at the International
Hydrocyclones, BHRA Fluid Engineering, Cambridge, 1980.
7. Young, G.A.B., Wakley, W.D., Taggart, D.L., Andrews, S.L.,
and Worrell, J.R.: “Oil-Water Separation Using Hydrocyclones:
an Experimental Search for Optimum Dimensions”, Journal of
Petroleum Science and Engineering, Vol. 11 (1994), pp. 37-50.
8. Dirkzwager, M.: “A New Axial Cyclone Design for Fluid-Fluid
Separation”, PhD-thesis, Delft University of Technology, 1996.
9. Kjos, T., Michelet, J.F., and Kleppe, J.: “Down-Hole Water-Oil
Separation and Water Reinfection through Well Branches”,
paper SPE 30518 presented at the 1995 SPE Annual Meeting,
Dallas, Oct. 22-25.
10. Janssen, P.H., Van den Broek, W.M.G.T., Van Dijk, K.M.,
Cras, R.S.A., and Klauer, H.S.: “Characterisation of NearWellbore Oil/Water Morphology”, paper INGP-5(NT)-3
presented at the International Seminar in Practices of Oil and
Gas Exploration INGEPET 1996, Lima, Oct. 29 to Nov. 1.
Conclusions
The main conclusions of this paper are the following:
1. Measured removal efficiencies of a plate separator and a
centrifuge are in good agreement with theoretical predictions.
2. With respect to performance in the sense of ratio (ffowrate)/(separator volume) and critical oil-droplet diameter, the
ranking of the three discussed separator types is: centrifuge,
hydrocyclone, plate separator.
3. Enhancement of separator performance through design
alterations is possible for all three separator types.
4. When the available space for separation is limited
(offshore production) to very limited (downhole separation), a
plate separator will not, or cannot, be used. Because of
economic reasons the chosen separator type is usually a
hydrocyclone.
5. There will remain a tendency to stive for more compact
separators. Both for hydrocyclones and centrifuges there are
possibilities in this respect.
6. When very small oil droplets, e.g. in the 5 pm range,
have to be removed, this can only be realized by using a
centrifuge. The high costs of this separation device, however,
are its main drawback.
Nomenclature
D = oil-droplet diameter
D= = critical oil-droplet diameter
D50 = oil-droplet diameter for which is valid: 50 vol. YO of
all oil droplets have a smaller diameter
g = acceleration of gravity
H= separator-channel height
L = separator-channel length
395
SPE 48870
WIM M.G.T. VAN DEN BROEK, ROBERT PLAT, AND MARK J. VAN DER ZANDE
6
TR EATEO
0 I I_— WATER
WATER
MIXTURE
------b-
&
+
+
Figure 2. Corrugated
Figure 1. Basic shape of a plate separator.
plates for a plate separator.
feed
I
G-force
D
G-force
<
Figure 3. Cross-section
centrifuge.
of the separation
section
of a disc-stack
3D View
Top View
Figure 4. Novel design: vertical plates for centrifugal separation.
Note: the total number of plates is typically of the order of a few
hundred, thus much larger than sketched here and in Fig. 5.
396
COMPARISON
SPE 48870
OF PLATE SEPARATOR,
CENTRIFUGE
AND HYDROCYCLONE
—
Uniform plate
distance
(PCC)
Uniform plate
thickness (PPC)
Flat
“
inlet
/’
,/’
i Straight
Q
,*underfow
overflow
Figure 6. Top view and side view of a hydrocyclone.
Curved
—
Figure 5. The
separation.
four
types
of vertical
channels
High pressure
Oil
for
centrifugal
pump
—-—0’--;
I
Needle
by-pass pump
valve
~—*__*. —
t
,-1
,.,
:! Flow
.,,,.:
.,
,.i
—-----.-j
‘++
\
SEPAR=
,
d
( “.,
..,
.1
Doppler
E
AZ!
B
Anemometer
Data
set-up for determining
diffraction
based
sizer
<’)
—.,
processing
the removal efficiency
397
Laser
particle
\
Oil
Laser
Water
Figure 7. Experimental
I
,,
meter
.- Valve
,.
.
:,
Water
unit
of a plate separator.
7
8
WIM M.G.T. VAN DEN BROEK, ROBERT PLAT, AND MARK J. VAN DER ZANDE
1
SPE 48870
,!
–t
,,,
I
... ,.,,,,,
.,, ,,
,,
,,,.,
,,
,.
,,
,,
—
,.
Q= 1.1110-4 m3/s
.
t
Ill
+ Corrugated
plates
.—-—
10
-1
100
D ~m]
Figure 8. Example of an experimentally
determined
,.
.
.Y.
w
removal efficiency
.,,,,
...’.
.,
..;,’.,
...
..,..
,,.
o.2 .-f
0
I
4“
~~
._
;,
,.
.
,.
,,
,.
,,
,.
I
Figure 9. Example of experimentally
determined
;
:..
,_
.
.,
:,,
:
,,,
,,,
.,,
.
of a plate separator.
,,,
,,,
.
.
.
.
.
.
.
,,,
,.,
,,.
.. :..., .. :.,,.., .,
,,,
,.
:,, ,.,
. ,.
,., .,,
,,
.,
,:
I ’300
(0.833)
m
,,,
removal efficiencies
for a centrifuge
with vertical separator
plates.
~
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