Abstrict An improved absorber for contacting gas having water entrained
therein with a liquid desiccant the absorber being in the form of
an upright vessel having a generally horizontal partition dividing
the vessel interior into a treating zone and a collection zone.
The partition has a collection bucket therein providing a reservoir
below the level of the partition and the partition has small diameter
opening spaced from the collection bucket. An upright tubular riser
is positioned within the vessel treating zone having an open bottom
extending within the partition bucket. A desiccant circulation conduit
is in the upper portion of the treating zone for dispersing fresh
liquid desiccant into the vessel. Packing is positioned within the
vessel treating zone. Liquid desiccant filters downwardly through
the packing as gas passing upwardly through the partition small
diameter openings and upwardly through the desiccant flooded packing
wherein water entrained in the gas is absorbed by the desiccant,
the gas, being substantially free of water, pass out of the vessel
at the upper end of the upper zone. A desiccant distribution conduit
passes desiccant out of the bucket and into the vessel collection
zone where the desiccant, having water absorbed therein, is removed
from the vessel. In an alternate embodiment a second partition divides
the vessel in second treating zone and a second collection zone
both spaced above the first mentioned treating and collection zones.
Liquid desiccant collected in the second cllection zone is passed
downwardly into the first mentioned treating zone.
Claims What is claimed is:
1. An improved absorber for contacting gas having water entrained
therein with a liquid desiccant, comprising:
an upright vessel having a generally horizontal partition therein
dividing the vessel interior into a treating zone and, below that,
a collection zone, the vessel having a gas inlet and a desiccant
outlet in the collection zone, a gas outlet in the treating portion
of the treating zone and a desiccant inlet in the treating zone,
the horizontal partition having a collection bucket means therein
providing a reservoir below the level of the partition, the partition
having a plurality of small diameter openings therein spaced from
the collection bucket;
an upright tubular riser positioned within said vessel having an
opening in the bottom and in the top, the bottom of the riser extending
within said collection bucket;
a desiccant circulation conduit connecting the interior of the
upper portion of said riser with said vessel collection zone;
packing within said treating zone; and
desiccant distribution means above said treating zone connected
to receive the flow of liquid desiccant therethrough, liquid desiccant
passing downwardly through said packing into said collection bucket
and upwardly within said riser and by said desiccant circulation
conduit into said collection zone and out through said desiccant
outlet, gas passing upwardly from said collection zone through said
small diameter openings in said partition and upwardly through said
packing to thereby contact desiccant passing downwardly through
said packing, at least a substantial portion of water in the gas
being absorbed by the liquid desiccant.
2. An improved absorber according to claim 1 wherein said opening
in the top of said riser is above said desiccant distribution means.
3. An improved absorber according to claim 1 wherein said riser
has an intermediate opening therein and wherein said desiccant circulation
conduit is connected to said intermediate opening.
4. An improved absorber according to claim 3 wherein said desiccant
circulation conduit extends at least partially exteriorly of said
vessel.
5. An improved absorber according to claim 1 including:
a short length vertical tubular member supported in each of said
small diameter openings in said partition and extending generally
vertically upward from said partition;
a bubble cap covering each of said tubular members, the internal
diameter of each bubble cap being greater than the external diameter
of said tubular member, each bubble cap having passageways therein
below the upper ends of said tubular members.
6. An improved absorber according to claim 5 wherein each said
bubble cap has an open bottom secured to said partition and a closed
top and said spaced apart passageways adjacent the cap bottom, and
having, above the spaced apart passageways, a plurality of smaller
diameter openings arrayed at substantially equal elevation above
said partition, the array of small diameter openings serving to
influence the depth of desiccant within said cap, said openings
being below the upper ends of said tubular members.
7. An improved absorber according to claim 1 wherein said partition
has an opening therein and wherein said desiccant circulation conduit
extends through such opening and communicates the upper interior
portion of said riser with said vessel collection zone.
8. An improved absorber according to claim 7 wherein said opening
in said partition is in said collection bucket and said desiccant
circulation conduit extends through such opening and within said
riser.
9. An improved absorber according to claim 8 wherein said desiccant
circulation conduit is substantially vertical and is received substantially
co-axially within said riser and has an upper end positioned within
the upper portion of said riser and a lower end positioned within
the lower portion of said vessel collection zone.
10. An improved absorber according to claim 1 including a second
generally horizontal partition spaced above said horizontal partition
dividing the vessel interior into a second treating zone and, below
that and above said treating zone, a second collection zone, and
including a second desiccant distribution means within said second
treating zone, the second horizontal partition having a collection
bucket means therein providing a reservoir below the level of the
second partition, the second partition having a plurality of small
diameter openings therein spaced from the collection bucket;
a second upright tubular riser positioned within said vessel having
an opening in the bottom and in the top, the bottom of the second
riser extending within said collection bucket in said second partition;
packing within said second treating zone;
a second desiccant circulation conduit connecting the interior
of the upper portion of said second riser with said desiccant distribution
means, whereby liquid desiccant passes downwardly through said packing
in said second treating zone into said collection bucket in said
second partition and upwardly within said second riser and by said
second desiccant circulation conduit into said desiccant distribution
means, then downwardly through said treating zone into said collection
bucket in said partition for ultimate discharge through said desiccant
outlet.
11. An improved absorber according to claim 10 wherein said opening
in the top of said second riser is above said second desiccant distribution
means.
12. An improved absorber according to claim 10 wherein said second
desiccant circulation conduit extends at least partially exteriorly
of said vessel.
13. An improved absorber according to claim 10 including:
a short length vertical tubular member supported in each of said
small diameter openings in said second partition and extending generally
vertically upward from said second partition;
a bubble cap covering each of said tubular members extending upwardly
from said second partition, the internal diameter of each such bubble
cap being greater than the external diameter of said tubular member,
each bubble cap having passageways therein below the upper ends
of said tubular members.
14. An improved absorber according to claim 13 wherein each said
bubble cap has an open bottom secured to said second partition and
a closed top and said spaced apart passageways adjacent the cap
bottom, and having, above the spaced apart passageways, a plurality
of smaller diameter openings arrayed at substantially equal elevation
above said second partition, the array of small diameter openings
serving to influence the depth of desiccant within said cap, said
openings being below the upper ends of said tubular members.
15. An improved absorber according to claim 10 wherein said second
partition has an opening therein and wherein said second desiccant
circulation conduit extends through such opening and communicates
the upper interior portion of said second riser with said vessel
second collection zone.
16. An improved absorber according to claim 15 wherein said opening
in said second partition is in said collection bucket therein and
said second desiccant circulation conduit extends through such opening
and within said second riser.
17. An improved absorber according to claim 16 wherein said second
desiccant circulation conduit is substantially vertical and is received
substantially co-axially within said second riser and has an upper
end positioned within the upper portion of said second riser and
a lower end positioned within the lower portion of said vessel second
collection zone.
Description SUMMARY OF THE INVENTION
This disclosure relates to an improved apparatus for extracting
water from wet gas to provide, at the outlet, gas substantially
free of water. The disclosure is particularly applicable to the
processing of natural gas having entrained water of sufficient quantity
to make its transportation and storage difficult. The absorber to
be herein described is of the type adaptable to be located at a
point adjacent the area where gas is produced and collected and
for removing entrained water from the gas so that the gas can be
more economically and efficiently transported, stored, processed
and used.
The improved absorber of this disclosure uses the well-known method
of extracting water from gas with liquid desiccant, usually glycol.
The process is sometimes referred to as "glycol dehydration"
or "liquid desiccant dehydration" in which wet gas is
mixed with and/or contacted with glycol or some other liquid desiccant.
The desiccant absorbs water from the gas but does not absorb the
gas. The desiccant, usually glycol, is then heated to evaporate
the water from it and the anhydrous glycol is recirculated through
the absorber in a continuous process.
The improved absorber of this disclosure provides a system in which
gas is intimately contacted with the desiccant for more improved
extraction of water in a vessel utilizing minimal components for
economy of construction and maintenance. The absorber herein described
has the characteristic of accepting a wide range of flow rates and
is particularly useful for accepting relatively low flow rates.
The improved absorber of this disclosure is formed of an upright
vessel having a generally horizontal partition therein dividing
the vessel interior into a treating and a collection zone. The vessel
has a gas inlet and a desiccant outlet in the collection zone. In
the treating zone the vessel has a gas outlet and a desiccant inlet.
The horizontal partition (also sometimes referred to as a "tray")
has a collection bucket as a part thereof. The collection bucket
is in the form of a recess portion in the horizontal partition,
the bucket having a bottom that is at a lower elevation than the
partition. The bucket forms a collection area within the vessel
treating zone where glycol, having water absorbed therein, collects.
An upright tubular riser is positioned within the vessel. The riser
has an open bottom and an open top. The bottom of the riser extends
within the collection bucket with the bottom of the riser spaced
above the bucket floor.
A desiccant circulation conduit connects the interior of the upper
portion of the riser with the vessel collection zone. In one embodiment
the desiccant circulation conduit is exterior of the riser and extends
through an opening in the vessel wall treating zone and an opening
in the vessel wall collection zone so that desiccant flows upwardly
within the riser and out of the riser through the desiccant circulation
conduit into the vessel collection zone where it is removed through
the desiccant outlet.
In another embodiment the desiccant circulation conduit extends
vertically within the riser through an opening in the floor of the
collection bucket and into the collection zone. The vertical desiccant
circulation conduit is open at each end so that the desiccant flows
upwardly within the riser to enter the circulation conduit. The
desiccant then flows downwardly through the circulation conduit
into the vessel collection zone where the spent desiccant is removed.
Packing is positioned within the vessel treating zone supported
on the partition.
A desiccant distribution pipe is mounted within the vessel treating
zone in communication with the desiccant inlet. Anhydrous desiccant,
that is, desiccant that is substantially free of water, enters the
desiccant distributor pipe where it is discharged downwardly onto
the packing. The desiccant trickles downwardly through the packing
and encounters gas flowing upwardly therethrough so that the desiccant
absorbs water from the gas. The gas passes upwardly through the
packing wherein substantially all of the water entrained therein
is absorbed and passes out of the vessel through the gas outlet
in the upper end of the treating zone.
The horizontal partition has a plurality of small diameter openings
therein spaced from the collection bucket. Mounted in each of the
openings is a short length vertical tubular member that extends
upwardly into the treating zone. Positioned over each of the tubular
members is a bubble cap. The internal diameter of the bubble cap
is greater than the tubular member external diameter, providing
an annular area within the bubble cap. Each bubble cap has passageways
below the upper end of the tubular member. Gas, having water entrained
therein, flows into the vessel through the gas inlet opening and
enters the vessel collection zone. The gas then passes upwardly
through the short length tubular members into the interior of the
bubble caps and then out of the bubble caps through the passageways
therein. The gas then flows upwardly through the packing as previously
described.
An alternate embodiment of the absorber includes a second generally
horizontal partition spaced above the first partition. The second
partition divides the vessel interior into a second treating zone
and, below that and above the first treating zone, a collection
zone. The desiccant distribution pipe is mounted within the second
treating zone in communication with the desiccant inlet.
The second horizontal partition, or tray as it is sometimes called,
has a collection bucket as a part thereof of the type described
with reference to the first mentioned horizontal partition. Further,
the second horizontal partition has a plurality of small diameter
openings spaced away from the collection bucket. Mounted in each
of the openings in a short vertical tubular member that extends
upwardly within the second treating zone. Positioned over each of
the tubular members is a bubble cap in the same manner as is described
with reference to the first horizontal partition.
A second upright tubular riser is positioned within the vessel
second treating zone. The riser has an open bottom and an open top,
and the bottom of the riser extends within the collection bucket
portion of the second horizontal partition. A second desiccant circulation
conduit connects the interior of the upper portion of the second
riser with the vessel second collection zone. Liquid desiccant flows
into the upper portion of the upper treating zone and downwardly
through the second treating zone which is filled with packing, into
the collection bucket of the second partition, upwardly into the
second riser and into the desiccant distribution pipe where it is
passed downwardly into the second collection zone and into the first
mentioned desiccant distribution pipe. Here the liquid desiccant
is again discharged into the interior of the vessel to flow downwardly
through the first treating zone to the first partition collection
bucket where it passes upwardly into the first tubular riser and
downwardly through the desiccant distribution pipe into the first
collection zone. Liquid desiccant having water absorbed therein
is removed from the first collection zone for recycling. The gas
having water entrained therein passes into the interior of the vessel
in the first collection zone, upwardly through the first partition
into the first treating zone which is filled with packing and upwardly
through such packing into the second collection zone. From the second
collection zone the gas passes upwardly through the second partition
and through packing in the second treating zone. The gas continues
to the upper end of the second treating zone where the gas passes
out of the vessel through the gas outlet.
The alternate embodiment thus replicates the basic concept of the
absorber into a vertical tandem arrangement for improved contact
of liquid desiccant with the gas being treated. The alternate embodiment,
while more expensive to manufacture, (having more components) is
capable of accepting gas at a wider range of flow rates than is
characteristic of absorbers presently used.
A better understanding of the invention will be had by reference
to the following description of the preferred embodiments and the
claims, taken in conjunction with the attached drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational cross-sectional view of the improved absorber
of this disclosure for use in dehydrating gas.
FIG. 2 is a cross-sectional view taken along the line 2--2 of the
absorber of FIG. 1 showing the riser, the collection bucket in the
partition and the bubble caps. Packing which ordinarily would be
seen in FIG. 2 is not shown so as to reveal the details of the other
features of the absorber.
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG.
1 showing the desiccant distributor in the upper portion of the
upper zone and showing the top of the riser.
FIG. 4 is an elevational cross-sectional view of the improved absorber
showing an alternate embodiment for desiccant circulation within
the absorber. In the embodiment of FIG. 4 the desiccant circulation
conduit system is entirely within the interior of the vessel.
FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG.
4 showing the interior details of the system. FIG. 5 does not show
the packing so as to reveal more details of the internal construction
of the absorber.
FIG. 6 is an enlarged elevational view of a bubble cap of the type
employed in the absorber and as seen in FIGS. 1 2 4 and 5.
FIG. 7 is a cross-sectional view taken along the line 7--7 of FIG.
6 showing the tubular riser extending from the partition and the
bubble cap covering the tubular riser.
FIG. 8 is an elevational cross-sectional view of an alternate embodiment
of the improved absorber wherein the vessel has two horizontal partitions
dividing it into first and second treating zones and first and second
collection zones in vertical tandem arrangement.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings and first to FIG. 1 a first embodiment
of the improved absorber of this disclosure is shown. The absorber
is formed by an upright vessel 10 having a bottom 12 and a top 14.
Positioned within the vessel is a horizontal partition 16 which
in the trade may be referred to as a "tray" or "plate
element". The horizontal partition 16 divides the vessel into
a treating zone 18 and a collection zone 20 the treating zone being
larger than the collection zone.
Formed in the vessel is a gas inlet 22 that communicates with the
vessel collection zone 20. A gas outlet 24 is provided in vessel
top 14 and communicates with treating zone 18. The gas passing into
vessel 10 typically has water vapor entrained therewith that is
characteristic of gas flowing from formations in the earth. It is
important that the water be substantially removed to facilitate
transportation and processing of the gas. Water entrained in gas
is highly deleterious. The water tends to collect in flow lines
and forms hydrates that can block the lines. In cold weather collected
water freezes to cause blockage problems. Further, the entrained
water interferes with processing and use of the gas. For these various
reasons, it is important that as much of the water as is practically
possible be removed from the gas as early as possible in the gas
handling processes. Thus, vessel 10 is of the type that may be located
in a gas field, adjacent gas producing wells and is normally used
for treating the gas before it is introduced into pipelines for
further distribution.
The gas is dehydrated in vessel 10 by contact with a liquid desiccant,
such as glycol. The anhydrous liquid desiccant is conveyed into
the vessel through desiccant inlet 26 and the spent or wet desiccant
is removed from the vessel through desiccant outlet 28 that communicates
with vessel collection zone 20.
An important feature of the absorber of FIG. 1 is the provision
in the horizontal partition 16 of a collection bucket 30. The bucket
is preferably centrally positioned in partition plate 16 and is
preferably formed integrally with it as illustrated. Collection
bucket 30 has a bottom floor 32 that is elevationaly positioned
below horizontal partition 16. The collection bucket 30 provides
a collection point for spent glycol in a manner to be described
subsequently.
Communicating with collection bucket 30 is a clean-out conduit
34. is provided merely as a means of cleaning the interior of the
collection bucket. Conduit 34 extends through the wall of vessel
10 but does not form a part of the gas flow or liquid desiccant
flow arrangement within the vessel.
The horizontal partition 16 has a plurality of small diameter openings
36 spaced away from collection bucket 30 openings 36 being seen
in dotted outline in FIGS. 2 and 5. As shown in FIGS. 6 and 7 positioned
within each of the small diameter openings 36 is a short length
vertical tubular riser 38. Each tubular riser is welded to partition
16 at each of openings 36.
Positioned over the top of each of the short length tubular risers
38 is a bubble cap 40. The internal diameter of each of the bubble
caps 40 is greater than the external diameter of tubular risers
38 leaving an annular area within bubble cap 40. Each of the bubble
caps is secured, such as by welding, at its lower end to horizontal
partition 16.
Formed in each of the bubble caps, below the upper end 38A of each
of the short length tubular risers, are a plurality of passageways
42. The passageways are illustrated as elongated vertical slots,
although the configuration of the passageways can vary.
In addition, formed in each of bubble caps 40 above passageways
42 and below the upper end 38A of tubular riser 38 are a plurality
of small diameter openings 44. The small diameter openings 44 are
arrayed in a plane parallel to horizontal partition 16. The function
of passageways 42 and small diameter openings 44 will be described
subsequently.
Referring back to FIG. 1 supported within vessel 10 is an upright
tubular riser 46. The lower end 46A of the riser extends within
collection bucket 30 with the lower end spaced above the bucket
floor 32. Riser 46 is preferably centrally located within vessel
10 and when vessel 10 is cylindrical, riser 46 is preferably coaxial
with the vessel wall. The upper end 46B of the riser is open and
communicates with the upper portion of treatment zone 18. In the
illustrated arrangement, the upper end of riser 46 includes a reduced
diameter portion 48.
A substantial portion of the vessel treating zone 18 is filled
with packing 50. In FIG. 1 only a small portion of the packing is
shown so as not to obscure other features of the absorber. To maintain
the packing in position within the vessel and to augment distribution
of liquid desiccant, a screen 52 horizontally extends within the
interior of the vessel and is spaced above partition 16. Screen
52 allows liquid desiccant and gas to freely pass therethrough.
Extending within the vessel treating zone 18 is a desiccant distributor
54 that is in the form of a circular pipe having small diameter
openings in the bottom. Distributor 54 is connected to desiccant
inlet 26. Anhydrous desiccant passes into the vessel through distributor
pipe 54 to flow downwardly onto screen 52 and then trickles downwardly
through packing 50 where it is contacted by gas moving upwardly
through the packing. In FIG. 1 the path of liquid desiccant is indicated
by solid arrows, and the path of gas is indicated by dotted arrows.
Riser 46 has an opening 56 intermediate the upper and lower ends
thereof. Connected to the interior of the riser through opening
56 is a desiccant circulation conduit 58. The desiccant circulation
conduit 58 extends partially exteriorly of vessel 10. Conduit 58
communicates between the interior of riser 46 and the vessel collection
zone 20.
The physical features of the absorber of FIGS. 1 2 3 6 and 7
having been described, the method of operation will now be set forth.
Liquid desiccant is introduced into the vessel through distributor
54 trickles downwardly through screen 52 and packing 50 and meets
gas moving in the opposite direction, as indicated by the dotted
arrows. Gas, having water entrained therein, enters the vessel collection
zone 20 through gas inlet 22. The gas passes upwardly through the
plurality of short length tubular risers 38 extending upwardly from
the horizontal partition 16. The gas flows within bubble caps 40
and out through passageways 42 and small diameter openings 44. The
gas migrates upwardly through packing wherein it intimately contacts
the downwardly migrating liquid desiccant which absorbs water from
the gas. The gas passes through screen 52 into the upper portion
of the vessel treating zone 18 and then through a demister 60 where
any entrained droplets of desiccant are intercepted. The dry gas
passes out of the vessel through gas outlet 24.
As the liquid desiccant flows downwardly through packing 50 it
accumulates in the collection bucket 30 and rises within riser 46.
When the level of glycol within riser 46 reaches opening 56 the
glycol flows through desiccant circulation conduit 58 into the vessel
collection zone 20. The spent desiccant, having water entrained
therein, is removed from the collection zone through desiccant outlet
28.
The small diameter openings 44 in bubble caps 40 provide gas outlet
during minimal flow conditions, whereas during high flow conditions
gas passes through the bubble caps 40 both through the smaller diameter
openings 44 as well as the much larger passageways 42. During minimal
gas flow conditions, the smaller diameter openings 44 provide a
means of ensuring maximum contact between the in flowing gas and
the liquid desiccant.
Referring now to FIGS. 4 and 5 an alternate embodiment of the
invention is illustrated. All features of the embodiment of FIGS.
4 and 5 are the same as those described with reference to FIG. 1
except for the desiccant circulation system. In FIGS. 4 and 5 rather
than using a desiccant circulation conduit that extends partially
exteriorly of the vessel as in FIG. 1 a vertical desiccant circulation
conduit 62 is employed. The vertical conduit 62 is positioned coaxially
of riser 46 and is received in an opening 64 in the collection bucket
floor 32. The lower end 62A of the vertical desiccant circulation
conduit extends into the lower portion of the vessel collection
zone 20 and the upper end 62B is open and is at an elevation intermediate
the upper and lower ends of the riser 46. The upper end 62B of the
desiccant circulation conduit is at substantially the same elevation
as the intermediate opening 56 in riser 46 as illustrated in FIG.
1.
The embodiment of FIGS. 4 and 5 functions the same as described
with reference to the embodiment of FIGS. 1 2 and 3 except that
the desiccant circulation conduit is entirely internally of the
vessel. As desiccant rises within riser 46 out of collection bucket
30 it enters the open top 62B of the vertical desiccant circulation
conduit and flows downwardly in the conduit into vessel collection
zone 20. Spent desiccant is removed through desiccant outlet 28
in the same manner as described with reference to FIG. 1.
During normal flow conditions the level of liquid desiccant within
the vessel is determined, with respect to FIG. 1 by the elevation
of opening 56 and riser 46 whereas in the embodiment of FIG. 4
it is determined by the elevation of the vertical desiccant circulation
conduit upper end 62B.
FIG. 8 shows an alternate embodiment of the invention. In essence
FIG. 8 utilizes a tandem arrangement of the embodiment of FIGS.
4 and 5. The numbers identifying elements in FIG. 8 identify corresponding
elements in FIGS. 4 and 5. In the embodiment of FIG. 8 a second
horizontal partition plate 66 is employed positioned elevationaly
above the first horizontal partition plate 16. The second partition
plate 66 is identical to that of the first horizontal plate 16 and
a downwardly extending cross-sectional view of such plate would
appear the same as in FIG. 5. Second horizontal plate 66 has a collection
bucket 68 formed as a part thereof with a clean-out conduit 69.
Plate 66 has openings therein with short length tubular members
(not seen in FIG. 8) the same as shown in FIG. 7 and with bubble
caps 70 which are in all respect like bubble caps 40 of FIGS. 4
5 6 and 7. Collection bucket 68 has a floor 72.
Formed above the second horizontal partition plate 66 is a second
treating zone 74 and below partition plate 66 is a second collection
zone 76. The second collection zone 76 is above and could be considered
the upper portion of the first treating zone 18.
Packing 78 is retained in the lower portion of second treating
zone 74 by the second horizontal partition plate 66 and by a screen
80. A second riser 82 is vertically positioned within the second
treating zone 74 the lower end of which is received within collection
bucket 68. The upper end of riser 82 is above screen 80 and terminates
with a reduced diameter portion 84.
Received within riser 82 is a second vertical desiccant conduit
86 having an upper end 86A which is positioned intermediate the
length of second riser 82. The lower end 86B of the vertical desiccant
circulation conduit receives piping 88 which extends exteriorly
of vessel 10. Piping 88 is configured in the U-shape exterior of
the vessel and reenters the vessel to connect to desiccant distributor
54.
Positioned in the upper portion of the second treating zone 74
is a second desiccant distributor 90 which receives the flow of
anhydrous desiccant, such as anhydrous glycol, into the absorber.
The absorber of FIG. 8 functions essentially as has been described
with reference to the absorber 54 except in tandem arrangement.
That is, the absorber system of FIG. 4 is substantially duplicated
in vertical arrangement within the same vessel. Gas having water
entrained therein enters the vessel at gas inlet 22 and flows upwardly
through first partition plate 16 through packing 50 in treating
zone 18 and past screen 52. The upward migration of the gas is
indicated by the dashed arrows in FIG. 8. The upward flow of gas
through the first treating zone 18 contacts downwardly flowing gylcol
by which water is absorbed therefrom. Gas continues to flow upwardly
through the second horizontal partition plate 66 out through bubble
caps 70 through packing 78 contained in the second treating zone
74 where the gas further contacts downwardly descending glycol.
Any water remaining in the gas is absorbed by the glycol in the
second treating zone. The gas passes ultimately through demister
60 and out through the gas outlet 24.
The desiccant inlet is designated as 26A in FIG. 8. Anhydrous desiccant
enters the vessel at this point and is distributed by the second
desiccant distributor 90. The liquid desiccant flows downwardly
past screen 80 and through packing 78. The liquid desiccant collects
in bucket 68 formed in the second horizontal partition plate 66.
The liquid desiccant flows upwardly within second riser 82 as indicated
by the solid arrows. The desiccant enters the upper end 86A of the
second desiccant circulation conduit 86 and flows downwardly therethrough
into piping 88. The liquid desiccant passes out of the vessel and
through the U-shaped piping 88 exterior of the vessel. The liquid
desiccant flows back into the interior of the vessel at a second
desiccant inlet 26B and into the first desiccant distributor 54.
The desiccant from distributor 54 flows downwardly through packing
58 into bucket 30 upwardly within the first riser 46 into the top
62B of the vertical desiccant circulation conduit 62 and out the
lower end thereof into collection zone 20. The desiccant having
water absorbed therein flows out of the vessel through desiccant
outlet 28.
The piping 88 is in a U-shaped configuration exterior of the vessel
to form a fluid trap to thereby prevent the passage of gas from
the second collection zone 76 into the second treating zone 74 by
way of piping 88. In other words, liquid desiccant collects within
the U-shaped trap formed by piping 88 to form a gas block to ensure
that gas passes in the vessel in the manner indicated by the dotted
arrows to be fully contacted by downwardly descending liquid desiccant.
The embodiment of FIG. 8 is employed when a high degree of gas
dehydration is required or when circumstances require an absorber
which can absorb water from gas over widely varying flow rates.
The claims and the specification describe the invention presented
and the terms that are employed in the claims draw their meaning
from the use of such terms in the specification. The same terms
employed in the prior art may be broader in meaning than specifically
employed herein. Whenever there is a question between the broader
definition of such terms used in the prior art and the more specific
use of the terms herein, the more specific meaning is meant.
While the invention has been described with a certain degree of
particularity, it is manifest that many changes may be made in the
details of construction and the arrangement of components without
departing from the spirit and scope of this disclosure. It is understood
that the invention is not limited to the embodiments set forth herein
for purposes of exemplification, but is to be limited only by the
scope of the attached claim or claims, including the full range
of equivalency to which each element thereof is entitled. |