U.S. patent application number 12/095400 was filed with the patent office on 2009-05-21 for gas-liquid contactor.
This patent application is currently assigned to Specialist Process Technologies Limited. Invention is credited to Kevin E. Collier, Theodore E. Dickinson, David J. Parkinson.
Application Number | 20090130007 12/095400 |
Document ID | / |
Family ID | 35685843 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090130007 |
Kind Code |
A1 |
Dickinson; Theodore E. ; et
al. |
May 21, 2009 |
Gas-Liquid Contactor
Abstract
A contactor for reacting a flow of gas with a liquid, comprises
a vessel, a first chamber in the vessel and a second chamber in the
vessel, the first and second chambers being linked only by a porous
wall, and means for directing ultrasonic noise into at least one of
the first and second chambers.
Inventors: |
Dickinson; Theodore E.;
(Huffman, TX) ; Parkinson; David J.; (Clevedon,
GB) ; Collier; Kevin E.; (Kaysville, UT) |
Correspondence
Address: |
HONIGMAN MILLER SCHWARTZ & COHN LLP
38500 WOODWARD AVENUE, SUITE 100
BLOOMFIELD HILLS
MI
48304-5048
US
|
Assignee: |
Specialist Process Technologies
Limited
Tortola
IO
|
Family ID: |
35685843 |
Appl. No.: |
12/095400 |
Filed: |
November 29, 2006 |
PCT Filed: |
November 29, 2006 |
PCT NO: |
PCT/GB2006/004481 |
371 Date: |
October 15, 2008 |
Current U.S.
Class: |
423/220 ;
422/128 |
Current CPC
Class: |
B01D 53/78 20130101;
B01J 19/26 20130101; C10L 3/10 20130101; C10L 3/102 20130101; B01J
10/00 20130101; B01J 19/10 20130101; B01J 19/008 20130101; B01D
2259/816 20130101; B01D 53/18 20130101; B01J 2219/0884
20130101 |
Class at
Publication: |
423/220 ;
422/128 |
International
Class: |
B01D 53/52 20060101
B01D053/52; B01J 19/10 20060101 B01J019/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2005 |
GB |
0524479..3 |
Claims
1-14. (canceled)
15. A contactor for reacting a flow of gas with a liquid, the
contactor comprising: a vessel; first and second chambers defined
within the vessel and disposed one within the other; a porous wall
providing the sole communication between the first and second
chambers; a gas inlet for the first chamber; a liquid inlet and a
liquid outlet for the second chamber; and means for directing
ultrasonic noise into at least one of the first and second
chambers, whereby gas entering the first chamber through the gas
inlet passes through the porous wall to the second chamber to mix
with the liquid.
16. A contactor as claimed in claim 15 in which the porous wall is
made from a sintered metal.
17. A contactor as claimed in claim 15, in which the means for
directing ultrasonic noise is adapted to direct pulsed ultrasonic
noise into at least one of the first and second chambers.
18. A contactor as claimed in claim 15, in which ultrasonic
transducers are disposed around the outside or inside of the
vessel.
19. A contactor as claimed in claim 15, in which the vessel is
substantially tubular, and the first and second chambers are both
substantially tubular.
20. A contactor as claimed in claim 19, in which the outlet extends
from the end of the second chamber, and lies substantially on the
central axis of the vessel.
21. A contactor as claimed in claim 15, in which the liquid inlet
is substantially radial to the second chamber and a deflector is
disposed in or adjacent the liquid inlet for directing incoming
flow to swirl around the second chamber.
22. A contactor as claimed in claim 21, in which the first chamber
is disposed within the second chamber.
23. A contactor as claimed in claim 15 in which the liquid inlet
extends substantially tangentially into the second chamber.
24. A contactor as claimed in claim 23, in which the second chamber
is disposed within the first chamber.
25. A contactor as claimed in claim 23, in which the second chamber
is a cyclone, having a substantially cylindrical upper portion and
a conical lower portion, the central axis of the vessel being
disposed substantially vertically in use.
26. A contactor as claimed in claim 25, in which a further outlet
extends from the upper end of the cyclone into the second chamber,
an open end of the outlet being positioned on the central axis of
the second chamber.
27. A process apparatus comprising a containment vessel having a
plurality of outlets at different vertical levels, and a plurality
of contactors, each contactor comprising: a vessel; first and
second chambers defined within the vessel and disposed one within
the other; a porous wall providing the sole communication between
the first and second chambers; a gas inlet for the first chamber; a
liquid inlet and a liquid outlet for the second chamber; and means
for directing ultrasonic noise into at least one of the first and
second chambers, whereby gas entering the first chamber through the
gas inlet passes through the porous wall to the second chamber to
mix with the liquid, in which the liquid outlet from each contactor
is connected to the containment vessel.
28. A method of operating a contactor which comprises: a vessel;
first and second chambers defined within the vessel and disposed
one within the other; a porous wall providing the sole
communication between the first and second chambers; a gas inlet
for the first chamber; a liquid inlet and a liquid outlet for the
second chamber; and means for directing ultrasonic noise into at
least one of the first and second chambers, whereby gas entering
the first chamber through the gas inlet passes through the porous
wall to the second chamber to mix with the liquid, in which method
a gas is fed into the first chamber, and a liquid is fed into the
second chamber, the gas being caused to pass through the porous
wall to react with the liquid, whilst ultrasonic noise is directed
to pass through the reacting liquid and gas in the second chamber.
Description
[0001] The present invention relates to an apparatus and method for
reacting a gas stream with a liquid, and more particularly to an
improved gas-liquid contactor and method of operating the same.
BACKGROUND TO THE INVENTION
[0002] Natural gas can contain a number of non-hydrocarbon
impurities both in the formation prior to extraction and/or
following extraction at a wellhead. Some of these impurities are
detrimental to efficient pipeline operation, whereas others have no
effect on pipeline efficiency, but do affect the heat content or
Btu rating of the natural gas.
[0003] Nearly all natural gas contains some water vapor when
extracted. The water vapor content in natural gas can be much lower
than saturation, but is usually higher than that desired for
satisfactory pipeline operation. The formation of free water in
pipelines caused by pressure and/or temperature reduction can
result in the formation of hydrates. In addition to the problem of
hydrates, the formation of free water or condensation can add to
the power requirements involved in distributing gas through
pipelines, due to increased pressure drops caused when water
collects in low spots in the line and reduces the pipeline flow
area for the gas. This condition is also conducive to corrosion in
the pipe. Water vapor is therefore usually removed from the gas,
and various methods are used for removal of these vapors.
[0004] Sour gas is the name commonly given to natural gas
containing hydrogen sulphide H.sub.2S. H.sub.2S is found in natural
gas in concentrations varying from a trace up to 30% by weight. The
presence of H.sub.2S causes severe corrosion to occur when free
water is present in natural-gas pipelines. When burned, H.sub.2S
forms sulphur dioxide, which is very toxic. The presence of
H.sub.2S in natural gas is therefore a serious problem. Mercaptans,
when airborne, can also present a problem because they have a foul
smell.
[0005] Nitrogen is also frequently found in natural gas. It has no
detrimental effects other than to lower the heat content of the
gas. Oxygen is sometimes encountered in natural gas, but the
quantities are usually so low as to be negligible. Another impurity
that is only rarely encountered is helium, and the removal of
helium is a specialized low-temperature process. The basic
processes used for removal of hydrocarbons invariably result in the
removal of water vapors and unwanted acid components. The removal
of water vapor or the adjustment of dew points is normally achieved
by means of a glycol system that requires a counter current flow
tower and glycol recovery system. H.sub.2S is normally removed as a
gas using Amine systems, again requiring the Amine to be
regenerated, often by a heated system. Conventional systems and a
new compact contactor are described in US Patent No
PCT/US2005/0020038. Furthermore, U.S. Pat. No. 6,918,949 B1
describes a method of contacting large volumes of gas, and U.S.
Pat. No. 4,279,743 describes an air-sparged hydrocyclone.
[0006] It is an object of the invention to provide an improved
gas-liquid contactor or Rapid Mass Transfer unit (RMT).
SUMMARY OF THE INVENTION
[0007] According to the present invention there is provided a
contactor for reacting a flow of gas with a liquid, comprising a
vessel, a first chamber in the vessel and a second chamber in the
vessel, the first and second chambers being linked only by a porous
wall, and means for directing ultrasonic noise into at least one of
the first and second chambers.
[0008] It is an advantage of the contactor of the invention that it
can be used as a rapid transfer device having a minimum retention
or hold-up time within the unit. The contactor also minimizes the
pressure required at inlets to the contactor, described below.
[0009] It is a particular advantage of the contactor that it is
capable of rapid mass transfer of reactants, which react
substantially instantaneously, such as the reaction of sodium
silicates or sodium silicon with CO.sub.2, H.sub.2S, NO.sub.X and
SO.sub.X, i.e. contaminants in a fluid stream.
[0010] Preferably first and second inlets are connected to the
respective first and second chambers.
[0011] Preferably the porous wall is made from a sintered
metal.
[0012] Preferably an outlet is provided in the second chamber.
[0013] Preferably means is provided for directing pulsed ultrasonic
noise into at least one of the first and second chambers.
[0014] Preferably ultrasonic transducers are disposed around the
outside or inside of the vessel.
[0015] Preferably the vessel is substantially tubular, and the
first and second chambers are both substantially tubular and
disposed at least partly one within the other about a central
axis.
[0016] Preferably the outlet extends from the end of the second
chamber, and lies substantially on the central axis of the
vessel.
[0017] Preferably the second inlet is substantially radial to the
second chamber and a deflector is disposed in or adjacent the
second inlet for directing incoming flow to swirl around the second
chamber.
[0018] Preferably the first chamber is disposed within the second
chamber.
[0019] Alternatively the second inlet is substantially tangential
to the second chamber.
[0020] The second chamber may be disposed within the first
chamber.
[0021] Preferably the second chamber is a cyclone, having a
substantially cylindrical upper portion and a conical lower
portion, the central axis of the vessel being disposed
substantially vertically in use.
[0022] It is an advantage of the cyclone that the products of
reaction can be at least partly separated, e.g. into the gas and
liquid phase, within the contactor.
[0023] Preferably a further outlet extends from the upper end of
the cyclone into the second chamber, an open end of the outlet
being positioned on the central axis of the second chamber.
[0024] According to a further aspect of the invention there is
provided a process apparatus comprising a plurality of contactors
as claimed in any preceding claim in which the first outlet from
each contactor is connected to a containment vessel, having a
plurality of outlets at different vertical levels.
[0025] According to a further aspect of the invention there is
provided a method of operating a contactor described above in which
a gas is fed into the first chamber, and a liquid is fed into the
second chamber, the gas being caused to pass through the porous
wall to react with the liquid, whilst ultra sonic noise is directed
to pass through the reacting liquid and gas in the second
chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] For a better understanding of the present invention, and to
show more clearly how it may be carried into effect, reference will
now be made, by way of example, to the accompanying drawings, in
which:--
[0027] FIG. 1 is a sectioned schematic of a contactor unit;
[0028] FIG. 2 is a sectioned schematic of a cyclonic contactor
unit;
[0029] FIG. 3 is schematic representation of a manifolded cyclonic
compact contactor unit.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Referring first to FIG. 1 a gas-liquid contactor is
indicated generally at 10. The contactor 10 comprises a vessel
having a first tubular chamber 12 and a second tubular chamber 14.
The chambers 12, 14 have walls 13, 15, which are cylindrical and
lie on a central vertical axis 16, as viewed, with the first
chamber 12 disposed concentrically within the second chamber 16.
The first chamber 12 has an axial inlet 18 at its upper end and its
lower end 20 is sealed. The wall 13 of the first chamber 12 is
porous over part of the chambers length, as indicated at 22, and is
made from sintered metal.
[0031] The second chamber 14 has a substantially radial inlet 24,
with an inlet deflector 26 which in use, causes inward flow to
swirl in the second chamber 14, between the wall of the inner first
chamber 12 and the wall 15 of the outer second chamber 14. An
outlet 28 is provided at the lower end of the second chamber
14.
[0032] Ultrasonic transducers are disposed in a jacket 30 around
the second chamber 14, and are directed inwardly. Alternatively,
the transducers may be positioned within the second chamber 14.
[0033] In use, a gas stream, for example natural gas, for treatment
enters the contactor 10 through the axial inlet 18. A liquid, i.e.
a chemical, for example sodium silicon or sodium metasilicate, is
fed into the second chamber 14 through the substantially radial
inlet 24 and the deflector 26 causes the flow to swirl around the
outside of the tubular first chamber 12 in the second chamber 14,
which is shaped as an annulus. The flow passes through the annulus
and reports to the outlet 28. The gas in the first chamber 12
percolates through the porous sintered wall 22 of the chamber into
the swirling flow in the annulus where rapid contact with the
chemical takes place. Ultrasonic noise, which may be pulsed, is
directed through the gas liquid mixture, and accelerates the
reaction between the gas and liquid. The high frequency sound
produces cavitation within the fluid, known as "cold boiling",
which increases the surface area available for chemical wetting, as
well as agitation caused by the growth and implosion of cavitation
bubbles under elevated pressure.
[0034] A second embodiment of a contactor is indicated at 50 in
FIG. 2. The contactor 50 comprises a vessel having a first tubular
chamber 52 and a second part-tubular chamber 54 disposed
concentrically about an axis 56, within the first chamber. The
second chamber 54 is constructed as a cyclone unit with a
cylindrical wall 57 forming an upper portion 58 and a conical wall
59 forming a lower portion 60. A portion of wall between the inner
and outer chambers, indicated at 62, is porous and is made from
sintered metal. A tangential inlet 64 is provided at the upper end
of the second chamber 54 and an axial outlet 66 is provided at the
lower end of the chamber. An outlet 68 comprising a dip tub extends
axially through the top of the vessel and extends into the second
chamber, i.e. the cyclone chamber, to a position substantially at
the lower end of the cylindrical upper portion 58 adjacent the
conical portion. A gas inlet 70 is provided to the first chamber
52, also at its upper end. The first chamber 52 is sealed to the
second chamber 54, save for the porous wall 62, as in the first
embodiment. Ultrasonic transducers 72 are positioned around the
vessel in the manner of a jacket and are directed inwardly.
Furthermore, ultrasonic transducers 73 are disposed about the dip
tube and are directed outwardly towards the chambers.
[0035] In use, the gas stream for treatment enters the contactor 50
through the inlet 70 and the chemical enters the contactor through
the tangential inlet 64. The chemical swirls in the cyclone unit,
i.e. the second chamber 54, and the gas swirls within the annulus,
i.e. the first chamber 52, and is forced under pressure through the
porous sintered tubular wall 62 into the cyclone unit, where it
makes rapid contact with the chemical. As in the first embodiment,
the ultrasonic transducers 72 emit ultrasonic noise which creates
cavitation in the gas annulus and cyclone chamber to enhance the
reaction between the chemical and gas to be treated. The
ultra-sonic noise may be pulsed.
[0036] The gas is the lighter of the two phases, and migrates
through the chemical and exits through the dip tube 68 and passes
to an overflow outlet 71. The chemical, which is substantially
de-gassed, reports to the cyclonic conical section 60, which acts
as a back pressure and swirl accelerator within the unit. The under
flow passes through the outlet 66 and can be connected directly to
a de-gassing vessel and chemical collection vessel.
[0037] Referring now to FIG. 3, a manifold system is indicated
generally at 74. Inlet headers 76, 78 deliver fluid (gas) to be
treated and chemical to a plurality of contactors 50. The outlets
66 of the contactors report to an inlet means to vessel or tank 76,
which collects the liquid stream from the underflow of contactors
50. The vessel or tank 76 has a liquid level control including a
liquid interface level indicator and control means which allows
valve means to be actuated either manually or automatically to
remove different liquid phases via outlets 78 and 80 respectively.
Gas accumulates in the top of vessel 76 and is released under
pressure control via a control valve means on an outlet 82. The gas
reports to a light phase outlet header, which is in communication
with the overflow outlets 71 at the top of each cyclonic contactor
50, (not shown for clarity). This arrangement is preferably valved
to allow the flowrate through the system to be matched to in
incoming required flowrate by switching on and off individual
contactors as may be required.
[0038] The contactors described provide an improved means of
reacting a liquid chemical with natural gas to remove impurities
such as H.sub.2S.
[0039] The contactor 10,50 is unaffected by motion, and as such
finds utility, albeit not exclusively, on offshore floating
production systems such as FPSOs (Floating Production Storage and
Offloading) units or Tension Leg platforms. The contactor unit can
also be used to enhance existing systems and in many cases can
cause the redundancy and removal of re-boilers to regenerate glycol
or Amine, this large unit being replaced by a new centrifugal
clarifier.
[0040] A significant advantage of the second embodiment described,
is that a reaction vessel and cyclone unit are combined for the
treatment of a fluid stream. Not only is the apparatus capable of
reacting the gas and liquid reactants, but also can, at least
partially, separate the different phases based on their specific
gravity differential, after the reaction has taken place within the
contactor. The manifold system described with reference to FIG. 3
allows use of a process in which flow down turn or unit duty
standby is required, e.g. in the case of large fluctuating flow
rates.
* * * * *