U.S. patent application number 14/365263 was filed with the patent office on 2014-11-06 for contact and separation column and tray.
The applicant listed for this patent is SHELL INTERNATIONALE RESEARCH MAATSDCHAPPIJ B.V.. Invention is credited to Jannes Koppen, Eric Johannes Vos, Peter Mervyn Wilkinson.
Application Number | 20140327161 14/365263 |
Document ID | / |
Family ID | 47458939 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140327161 |
Kind Code |
A1 |
Koppen; Jannes ; et
al. |
November 6, 2014 |
CONTACT AND SEPARATION COLUMN AND TRAY
Abstract
A contact and separation column (1) encasing a stack of one or
more contact and separation cells (3). Each cell comprises: --a
tray (4) with gas flow openings (6) opening into contact and
separation units (7); --a downcomer (16) defining a liquid
discharge; and --a liquid supply (17). Each contact and separation
unit (7) comprises an upstream contact zone (8, 9) with liquid
inlets (12), and one or more downstream separation zones (10)
provided with a swirler (13) and a top end with a gas outlet (14).
The cross-sectional area of the contact zone (8, 9) is larger than
the cross-sectional area of the cross-sectional areas of the one or
more separation zones of the contact and separation unit in
question (10). Process for treating a gas with such a column.
Inventors: |
Koppen; Jannes; (Amsterdam,
NL) ; Vos; Eric Johannes; (Amsterdam, NL) ;
Wilkinson; Peter Mervyn; (Amsterdam, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL INTERNATIONALE RESEARCH MAATSDCHAPPIJ B.V. |
The Hugue |
|
NL |
|
|
Family ID: |
47458939 |
Appl. No.: |
14/365263 |
Filed: |
December 14, 2012 |
PCT Filed: |
December 14, 2012 |
PCT NO: |
PCT/EP2012/075598 |
371 Date: |
June 13, 2014 |
Current U.S.
Class: |
261/110 ;
261/114.5 |
Current CPC
Class: |
B01D 53/185 20130101;
B01D 53/18 20130101; C10L 3/102 20130101; B01D 2252/20484 20130101;
B01D 2252/20489 20130101; B01D 2256/245 20130101; Y02P 70/10
20151101; B01D 19/0057 20130101; B01D 3/20 20130101; B01D 2257/304
20130101; B01D 2257/504 20130101; B01D 53/1462 20130101; Y02P 70/34
20151101 |
Class at
Publication: |
261/110 ;
261/114.5 |
International
Class: |
B01D 53/18 20060101
B01D053/18 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2011 |
EP |
11194119.1 |
Claims
1. A contact and separation column (1) comprising a column wall (2)
encasing a stack of one or more contact and separation cells,
wherein each cell comprises: a tray (4) with a number of gas flow
openings (6) opening into one or more contact and separation units
(7) positioned on an upper side of the tray (4), wherein each
contact and separation unit (7) comprises an upstream contact zone
(8, 9) with liquid inlets (12), and one or more downstream
separation zones (10) provided with a swirler (13) and a top end
with a gas outlet (14); a downcomer (16) defining a liquid
discharge; and a liquid supply (17) for supplying liquid to the
contact and separation cell, wherein the contact zone (8, 9) has a
larger cross-sectional area than the one or more separation zones
of the contact and separation unit in question (10).
2. The contact and separation column of claim 1 wherein the
cross-sectional area of the contact zone (8, 9) is at least 50%
larger than the cross-sectional area of a single separation zone
(10).
3. The contact and separation column according to any one of the
preceding claims, wherein the cross-section of the contact zone (8,
9) is a square or rectangle.
4. The contact and separation column according to any one of the
preceding claims, wherein a contact and separation unit (7)
comprises a single contact zone (8, 9) and a plurality of
separation zones (10).
5. The contact and separation column according to any one of the
preceding claims, wherein the gas outlet (14) is bordered by a
liquid flow deflector (15).
6. The contact and separation column according to any one of the
preceding claims, wherein the liquid flow deflectors (15) comprise
a return skirt having a U-shaped radial cross section with an open
side arranged over a top edge of the separation zone (10).
7. The contact and separation column according to any one of the
preceding claims, wherein at least part of the contact zones (8, 9)
is filled with a packing material.
8. The contact and separation column according to any one of the
preceding claims, wherein the downcomers (16) in adjacent cells are
offset relative to each other and wherein the liquid discharge of
an upper contact and separation cell forms the liquid supply of a
lower contact and separation cell.
9. The contact and separation column according to any one of the
preceding claims, wherein at an edge of the tray (4) downcomers
(16) comprise a weir, wherein the weir and column wall (2) define a
liquid discharge.
10. A contact and separation tray for use in a contact and
separation column according to any one of the preceding claims,
wherein the tray (4) comprises a base plate (5) with a number of
gas flow openings (6) opening into one or more contact and
separation units (7) positioned on an upper side of the tray (4),
wherein each contact and separation unit (7) comprises an upstream
contact zone (8, 9) with liquid inlets (12), and one or more
downstream separation zones (10) provided with a swirler (13) and a
top end with a gas outlet (14) bordered by a liquid flow deflector
(15); wherein the contact zone (8, 9) has a larger cross-sectional
area than the separation zone (10).
11. The contact and separation tray of claim 10, wherein a weir is
present at an edge of the tray (4) which weir and column wall (2)
define a liquid discharge.
12. The contact and separation tray according to claim 10 or 11
wherein the contact and separation units (7) comprise a box shaped
contact zone (8, 9) opening into one or more tubular separation
zones (10).
13. Process of treating gas with a liquid which process comprises
introducing the gas at the gas inlet (6) and liquid at the liquid
inlet (12) in a lower contact and separation cell (3) of a contact
and separation column (1) according to any one of claims 1 to
9.
14. The process of claim 13 wherein the flow velocity of the gas in
the contact zone (8, 9) is lower than the flow velocity in the
separation zone (10).
15. The process of claim 14 wherein the gas is natural gas.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a contact and separation
column, particularly for high capacity gas/liquid mass transfer,
with a stack of one or more contact and separation cells, where gas
is intensively contacted with a liquid, which is first entrained
with the gas flow and which is subsequently removed from the gas
flow by centrifugal impact of a swirler. The invention also
pertains to a tray to be used in such a column and to a process for
treating a gas with such a column.
[0002] The column can for instance be a heat transfer column, a
fractionation column, a stripping column or a treating column, in
particular a treating column, more particular a column for treating
natural gas, to remove contaminants, such as carbon dioxide and/or
hydrogen sulphide.
BACKGROUND OF THE INVENTION
[0003] The term gas shall be used herein so as to also include
vapour while the term liquid also includes liquid containing gas
such as froth. The expression treating liquid is used to indicate
compounds, preferably liquids, which selectively removes
contaminants such as hydrogen sulphide and/or carbon dioxide by
physical and/or chemical phenomena.
[0004] Trays for gas/liquid mass transfer containing a cyclonic
gas/liquid separation device differ from regular mass transfer
trays in their range of applications. A tray in which gas and
liquid are contacted and subsequently separated with a cyclonic
gas/liquid device can be made significantly more compact than a
regular tray where the separation between gas and liquid is by
gravitational forces instead of centrifugal forces.
[0005] U.S. Pat. No. 6,227,524 describes contact and separation
elements (CSE's) for high speed mass transfer trays in which liquid
enters the CSE through an annular row of holes into a grid net of
vertical vanes dispersing the liquid into small droplets which
together with the gas move to the vanes of an axial swirler located
directly above the vertical vanes in which swirler the liquid-gas
flow is subjected to a rotary motion thereby creating an upwardly
moving rotating liquid film. The final gas/liquid separation takes
place in the separation zone located in the upper part of the CSE,
while the mass transfer mainly takes place in a small zone just
above the liquid inlet holes. The amount of liquid entering the
contact zone depends on a force balance where the liquid level (as
set by the height of the weir) around the CSE provides a
hydrostatic force for liquid to enter the CSE. In addition the gas
flow inside the CSE induces a suction force which increases inflow
of liquid into the CSE. These two forces are balanced by a
counterforce resulting from a pressure drop over the CSE,
particularly induced by the swirler and the narrowing transition
between the upstream contact zone and the downstream separation
zone. Ultimately the maximum capacity of this CSE will depend on
the pressure balance: as the gas rate to the device is increased
the pressure drop will increase. When the pressure drop inside the
contact zone exceeds a certain value (which depends on the liquid
height surrounding the CSE) part of the gas will escape through the
liquid inlets at which point the mass-transfer performance will
drop dramatically.
[0006] EP-A-0048508 describes an apparatus for treating mixtures of
liquid and gas at high flow velocities and/or high liquid loads.
The liquid flows through in once-through mode, i.e. without
internal recycle. Furthermore, the volume of the contact zone is
small compared to the volume of the separation zone while both
zones have the same diameter.
[0007] The mass transfer rate is related to the amount of liquid
entrained per unit of gas in the contact zone. The required
volumetric mass transfer rates increase with higher partial
pressure of the impurities (such as CO.sub.2) to be absorbed.
However, mass transfer rates obtainable with prior art contact and
separation columns were found to be limited.
[0008] In offshore gas mining contact and separation columns are
used with floating applications, e.g. on a floating device or boat.
Sea motion induced sloshing or waving of the liquid poses serious
limitations on the obtainable mass transfer and the effectiveness
of the columns.
[0009] It is an object of the invention to provide contact and
separation equipment enabling improved mass transfer.
[0010] It is a further object of the invention to provide robust
contact and separation equipment which can be used with floating
applications.
SUMMARY OF THE INVENTION
[0011] A contact and separation column is disclosed comprising a
column wall encasing a stack of one or more contact and separation
cells, wherein each cell comprises: [0012] a tray with a number of
gas flow openings opening into one or more contact and separation
units, wherein each contact and separation unit comprises an
upstream contact zone with liquid inlets, and one or more
separation zones provided with a swirler and a top end with a gas
outlet; [0013] a downcomer defining a liquid discharge for liquid
overflowing the downcomer, which has a height exceeding the level
of the liquid inlets; and [0014] a liquid supply for supplying
liquid to the contact and separation cell, wherein the contact zone
has a larger cross-sectional area than the one or more separation
zones of the contact and separation unit in question.
[0015] In a second aspect, a contact and separation tray is
disclosed for use in the disclosed column.
[0016] In a third aspect a process for treating gas is disclosed
making use of the disclosed column.
DETAILED DESCRIPTION
[0017] By having a cross-sectional area which is larger at the
contact zone than at the separation zone, a substantial increase of
the mean residence time in the contact zone is achieved and,
consequently, of the volumetric gas/liquid mass transfer rate. This
advantage can be further improved by spacing the swirler at a
distance from the gas inlet.
[0018] The cross-sectional area is the surface area of the section
made by a plane cutting the middle of the zone in question at a
right angle to the longest axis of the contact and separation cell.
The middle of a zone is taken in the direction of the longest axis
of the contact and separation zone together.
[0019] The cross-sectional area of the separation zone or zones of
the unit in question is the sum of cross-sectional areas of all
separation zones in fluid connection with the contact zone in
question. This can be a single separation zone but generally will
be 2 or more separation zones.
[0020] Due to the larger cross-sectional area of the contact zone,
the flow velocity of the gas in the contact zone will typically be
lower than the flow velocity in the separation zone. While lower
flow velocities result in improved mass transfer in the contact
zone, faster flow velocities in the separation zone result in
improved separation. The flow velocity can be represented by the
Souders-Brown density corrected gas load factor
Cs=U.sub.Gas*(.rho..sub.Gas/(.rho..sub.Liquid-.rho..sub.Gas)).sup.1/2.
[0021] To obtain a good centrifugal separation at the swirler this
factor can for instance be in the range of 0.3 m/s<Cs<1.5
m/s. Such velocities are very high, particularly compared with
regular prior art contacting devices (e.g., with trays or packing),
which typically operate at a Cs factor below 0.1 m/s. In the
contact zone such flow velocities would lead to very short
gas/liquid contacting times and low mass transfer rates. Due to the
larger cross-sectional area in the contact zone, the flow velocity
can be substantially lower. The flow velocity of the gas in the
contact zone can typically be at most 90%, preferably at most 80%
or even more preferably at most 50% of the flow velocity in the
separation zone.
[0022] An additional advantage of a larger cross-sectional area for
the contact zone is that it provides space for a larger gas inlet
area and a larger liquid inlet area, which will reduce the pressure
drop for the gas and liquid to enter the contact zone and thus lead
to a higher liquid suction rate while also contributing to better
mass transfer.
[0023] A further advantage of the present invention is that it
allows recycle of the liquid in a contact and separation unit which
makes that there is flexibility in the volume of fresh liquid to be
sent to the unit in question.
[0024] In a specific embodiment the downcomers of the trays can be
arranged offset relative to downcomers of a next tray, e.g.,
alternately at opposite sides in adjacent cells, wherein the liquid
discharge of an upper contact and separation cell forms the liquid
supply of a lower contact and separation cell. Liquid flowing into
the downcomer of an upper cell flows into the underlying cell where
it is circulated once again until it flows into the next
downcomer.
[0025] The expression "upstream" and "downstream" is used with
respect with the swirler.
[0026] The cross-sectional area of the contact zone can for
instance be at least 30% larger than the cross-sectional area of a
single separation zone, more specifically at least 50%, more
preferably at least 80%, most preferably at least 100%.
[0027] Preferably, the cross-sectional area of a contact zone is at
least 5% larger than the cross-sectional area of all separation
zones belonging to the same unit as this contact zone, more
specifically at least 8%, more preferably at least 10%. Most
preferably, the cross-sectional area of a contact zone is at most
50% larger than the cross-sectional area of all separation zones
belonging to the same unit as this contact zone.
[0028] Furthermore, the volume of a contact zone preferably is at
least 50% larger than the volume of all separation zones in direct
fluid communication with the contact zone in question, more
specifically at least 80%, more preferably at least 100%
larger.
[0029] The downcomers at an edge of the tray can comprise a weir
which weir and the edge are spaced from the column wall to define
the liquid discharge for liquid overflowing the weir. The weir can
be part of the tray or it can be a separate part. In an alternative
embodiment, the downcomer can for instance be a pipe or any other
suitable type of conduit. The tray may have one or more downcomers
of the same or different types.
[0030] The contact zone is provided with one or more inlets for
supplying liquid into the gas flow at a level below the top end of
the downcomer. In use the liquid inlets are submerged in the liquid
on the tray, i.e. the liquid inlets are below the liquid level of
normal operation. Preferably, the liquid inlets are at or near the
gas flow openings in the base plate of the tray, most preferably
the liquid inlets are covered by the gas inlets. The liquid inlets
can for example be slits or circular, square or triangular holes or
of any desirable alternative shape.
[0031] Optionally, liquid distributing means can be used for
distributing the liquid over the area of the gas flow openings in
the tray. This way, liquid is not only introduced peripherally into
the gas flow, but a more equal liquid distribution is obtained over
the full gas flow area. It has been found that this substantially
increases the mass transfer rate. Moreover, larger gas flow
openings and contact zones with larger cross-sectional areas can be
used, while maintaining high mass transfer rates. Examples of
guiding means which can be applied are vanes or gutters, e.g., with
a rectangular, semi-circular or V-shaped cross section.
[0032] The swirler can for example be a vane assembly imparting a
rotary movement to the gas/liquid mixture. By this rotary movement
the liquid droplets of the gas/liquid mixture are flung outwardly
to impinge and coalesce on the inner surface of the conduit.
[0033] The swirler can be located at a distance from the gas inlet
of from 50 to 90% of the total length of the contact and separation
zone, typically from 60 to 90%, preferably from 65 to 85%.
[0034] In a specific embodiment the contact zone is such that its
cross section is a square or rectangle. Preferably, the contact
zone may have the shape of a box, carrying one or more tubular
separation zones, such as cylindrical or conical separation zones.
Due to the box shape the contact zones can be arranged close
together, using a high proportion of the available space in the
respective cell.
[0035] Preferably, the gas outlet of the top end of the separation
zone is bordered by a liquid flow deflector.
[0036] Optionally, the liquid flow deflector comprises a return
skirt having a U-shaped radial cross section with an open side
arranged over a top edge of the separation zone. Due to the
centrifugal impact of the swirler, liquid borne by the passing gas
is collected on the cylindrical or conical inner wall of the
separation zone, where it flows upwardly under the influence of the
passing gas flow. At the upper edge of the contact zone, gas flows
upwardly through the outlet, while the separated liquid is
deflected by the return skirt to flow down again outside the
contact zone.
[0037] In a specific embodiment the cross-sectional area of the
contact zones together take up the majority of tray surface,
typically at least 60%, more specifically at least 70%, and
preferably at least 80%. In this respect the cross-sectional area
of the contact zones refers to the joint cross section of all
contact zones connected to the tray in question. The
cross-sectional area of the separation zones is not taken into
account. The high density of contact and separation zones reduces
sensitivity to sea motion induced tilt and motion, which makes this
device very suitable for floating applications. Fluid behaviour
inside the contacting and separation zones is virtually independent
of external motion and is dominated by the high gas flow rate
inside the contact and separation zone. Wave formation due to tilt
or motion can occur at the liquid surface between the contact and
separation zones. However, due to the limited space in between the
contact and separation zones waves cannot evolve, since the contact
and separation zones will dampen the wave formation.
[0038] When waves develop due to tilt or motion, the liquid level
on the tray will vary, but the impact will remain very small as
long as the wave height is relatively small in comparison with the
average liquid level on the tray. The liquid level on the tray can
be further increased by increasing the weir height, and optionally
also tray spacing. Weir heights (up to 700 mm) which are like a
factor 10 higher than on regular trays have been successfully
tested for this purpose.
[0039] The one or more contact and separation trays may form a
separate or integral part of the contact and separation column. The
tray comprises a base plate with a number of gas flow openings
opening into one or more contact and separation units positioned on
an upper side of the base plate. In a specific embodiment, each
contact and separation unit comprises an upstream contact zone with
liquid inlets which liquid inlets preferably are within the scope
of the gas flow openings, one or more downstream separation zones
provided with a swirler and a top end with a gas outlet bordered by
a liquid flow deflector;
wherein the contact zone has a larger cross-sectional area than the
separation zone.
[0040] The tray can comprise a weir at one or more of the tray
edges which weir can be part of the tray itself or it can be a
separate part or part of the column wall.
[0041] In a specific exemplary embodiment of the tray, the contact
and separation zones comprise a box shaped contact zone opening
into one or more tubular separation zones, typically cylindrical
and/or conical separation zones.
[0042] The contact zone can be empty, allowing free flow of the
passing gas, or it may wholly or partly contain a packing material,
such as corrugated plate material and/or wire mesh material. Such
packing material increases the residence time of the liquid in the
contact zone and, consequently, such packing supports further mass
transfer.
[0043] The column of the present invention will further be provided
with a liquid inlet, a liquid outlet, a gas inlet and a gas
outlet.
[0044] The disclosed contact and separation column can be used for
a process for treating gas with a liquid. To this end, gas is
introduced into the contact and separation zones via the gas flow
openings, while treating liquid at the liquid inlet in a lower
contact and separation cell of a contact and separation column.
[0045] The process can for example be used for treatment of gases
comprising water, carbon dioxide and/or hydrogen sulphide, such as
natural gas or shale gas. If mainly water is removed, the process
generally is called dehydration. Most preferably, the process is
used for removing carbon dioxide and/or hydrogen sulphide.
[0046] Natural gas is a hydrocarbon gas mixture containing a
substantial amount, preferably consisting of at least 40% wt, more
specifically at least 50% wt, most specifically of from 60 to 95%
wt, of methane. It is customary to temporarily liquefy natural gas
for ease of storage or transport. To prepare natural gas for
liquefaction it is treated to remove components that would freeze
under liquefaction conditions or that would be destructive to
liquefaction equipment, such as water, hydrogen sulphide and carbon
dioxide. The liquids for treating the gas can be any liquid known
to be suitable for this purpose. Typically, the liquids for
removing the undesired compounds will contain water, glycols,
methanol and/or amines, more specifically will be aqueous solutions
of one or more amines, more specifically alkylamines, more
specifically one or more compounds chosen from the group consisting
of monoethanolamine, diethanolamine, methyldiethanolamine,
diisopropanolamine and aminoethoxyethanol.
[0047] The mass transfer further can be improved by adding
compounds known as accelerators which further increase the speed of
chemical and/or physical interaction between the natural gas and
the treating liquid. The mass transfer can be increased further by
using a higher temperature for example by up to at most 30.degree.
C. above the normal operating temperature.
[0048] A further advantage of the intense mixing that takes place
in the contact zone of the present invention is the increased
selectivity for removing contaminants which have a higher
absorption rate into the liquid. Intense mixing for example tends
to favour absorption of hydrogen sulphide over carbon dioxide which
is highly advantageous when treating natural gas.
[0049] The disclosed process generally is designed to give almost
pure methane.
[0050] The process can also be used for treatment of other gases or
for stripping or fractionation, if so desired.
[0051] The invention will now be described by way of example in
more detail, with reference to the drawings, wherein
[0052] FIG. 1 shows schematically in plan view a contact and
separation column of the invention;
[0053] FIG. 2 shows the column of FIG. 1 in a longitudinal cross
section along line A-A in FIG. 1;
[0054] FIG. 3 shows a section of the interior of the column of FIG.
1 in perspective view;
[0055] FIG. 4 shows a different perspective view of the section
shown in FIG. 3.
[0056] FIGS. 1-4 show a contact and separation column 1 comprising
a column wall 2 encasing a stack of two contact and separation
cells 3. Each cell 3 comprises a tray 4 with a base plate 5
provided with a number of gas flow openings 6 opening into a
respective contact and separation unit 7 positioned on the upper
side of the tray 4. Each contact and separation unit 7 comprises a
box-shaped upstream contact zone 8, 9 and cylindrical separation
zones 10 on top of the contact zone 8, 9. The box shaped contact
zones 8, 9 include a larger middle box 8 and two smaller boxes 9
flanking the larger middle one. The larger middle contact zone 8
carries a row of three separation zones 10, while the two smaller
ones carry only two separation zones 10 as shown in FIG. 1. This
way, the cross-sectional area of each of the contact zones 8, 9 is
larger than the joint cross-sectional areas of the separation zones
10 in fluid connection with a single contact zone. As the contact
zone furthermore is much higher than the separation zones, the
volume of the contact zone is much larger than the volume of the
separation zones 10 in fluid connection with a single contact
zone.
[0057] At their lower ends the contact and separation units 7
comprise a set of parallel vertical plates 11 bridging the gas flow
openings 6 and spacing the contact zone 8, 9 from the base plate 5.
Gas can flow through the gas flow openings 6 via the space between
the vertical plates 11 into the contact zones 8, 9. The vertical
plates 11 define inlets 12 for liquid present in the cell 3.
[0058] The cylindrical separation zones 10 are provided with a
swirler 13 within their lower end. The top end 14 of the separation
zone forms a gas outlet which is bordered by a liquid flow
deflector 15 formed by a ring with a U-shaped radial cross section
with the open side arranged over the top edge of the separation
zone 10.
[0059] The tray 4 further comprises an edge with a weir, which is
spaced from the column wall 2 to define a liquid discharge 17 for
discharging liquid overflowing the weir to a lower cell 3. The
height of the weir determines the level of liquid present in the
cell 3. At the lower side of the tray 4 the weir extends to a
distance above the base plate 5 of a lower tray 4. This distance
corresponds to the height of the vertical plates 11. This way, the
weir and the adjacent section of the column wall 2 define a
downcomer 16 serving as a liquid supply 17 for the next cell 3
below.
[0060] The trays 4 in the column 1 are arranged in a mirrored
position relative to adjacent upper or lower trays. As a result,
the weir of each tray 4 is placed at a side of the column which is
opposite to the side where the weir of a tray 4 above or below is
arranged. With such an arrangement the weir of each tray 4 forms a
downcomer 16 supplying liquid to the next lower cell 3. In
alternative embodiments, other types of downcomers, such as pipes,
can also be used.
[0061] Liquid flows down from a downcomer 16 into a cell 3, where
the liquid is collected until it reaches the level of the upper
edge of the weir. Meanwhile gas flows in the direction indicated by
the arrow A in FIG. 2. The gas flows via the gas flow openings 6
upwardly into the cell 3, via the contact zones 8, 9 and the
separation zones 10 into the gas flow openings 6 of a next upper
cell 3. At the liquid inlets 12 of the contact zones 8, 9 the
liquid is forced to flow into the contact zone 8, 9 by a
hydrostatic force and a suction force exerted by the passing gas
flow. These forces are balanced by a counter force resulting from
the pressure drop in the gas flow due to the narrowing
cross-sectional area. Liquid will gradually enter the contact zone
8, 9 and be dispersed into the passing gas flow. Due to the
vertical plates 11 the liquid does not only enter the gas flow at
the periphery of the contact zone, but over a larger area of the
gas flow, resulting in an improved mass transfer of liquid into the
gas flow. The contact zone 8, 9 is relatively high which
contributes to a more intense contact between liquid and gas. When
passing the swirler 13, the gas flow undergoes a centrifugal force.
As a result liquid borne by the gas flow will be swept against the
inner wall of the separation zone 10 and pushed upwardly by the
passing gas flow. The gas flow exits the separation zone 10 via the
outlet 14. The separated liquid reaching the top edge of the
separation zone 8 is deflected by the return skirt 15 to the outer
side of the cylindrical wall, where it flows downwardly back into
the liquid of the cell 3.
* * * * *