U.S. patent number RE39,944 [Application Number 10/449,538] was granted by the patent office on 2007-12-25 for desiccant regenerator system.
Invention is credited to Rodney T. Heath.
United States Patent |
RE39,944 |
Heath |
December 25, 2007 |
Desiccant regenerator system
Abstract
A natural gas dehydrator wherein a portion of the wet glycol
from the absorber is pumped under pressure as circulating wet
glycol which is used as a coolant for effluents removed from a
reboiler and a power source for an educator to form a vacuum in a
first chamber of a liquid water removal separator apparatus. The
cooled effluents, comprising liquid water, liquid hydrocarbons and
uncondensed vapors, move in to the first chamber wherein the liquid
water is separated therefrom. The liquid hydrocarbons and the
uncondensed vapors are removed from the first chamber and move into
the eductor wherein they are combined into the circulating wet
glycol. The separated liquid water is transferred to a second
chamber of the liquid water removal separator apparatus and then
removed therefrom. Also, gases from gas emitting level control
apparatus in the natural gas dehydrator are collected and fed into
the first chamber.
Inventors: |
Heath; Rodney T. (Farmington,
NM) |
Family
ID: |
23301343 |
Appl.
No.: |
10/449,538 |
Filed: |
May 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09333115 |
Jun 15, 1999 |
06238461 |
May 29, 2001 |
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Current U.S.
Class: |
95/161; 95/163;
95/165; 95/166; 95/193; 95/231; 95/247; 95/266; 96/193; 96/266 |
Current CPC
Class: |
B01D
53/263 (20130101) |
Current International
Class: |
B01D
47/00 (20060101); B01D 53/26 (20060101) |
Field of
Search: |
;95/161-163,166,169,174-180,186,187,227-231,247,258,259,266
;96/158,162,163,165,168,193,182-185,245,250,262,266 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Environmental Technology Verification Report", Greenhouse Gas
Technology Center Southern Research Institute, no date. cited by
other .
"Natural Gas Dehydration", The Environmental Technology
Verification Program, (Sep. 2003). cited by other .
Archer, Phil, "TEG Regenerator Vapor Recovery in Amoco's
Northwestern Business Unit", Amoco Northwestern Business Unit,
(Aug. 1992). cited by other.
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Primary Examiner: Lawrence; Frank M.
Attorney, Agent or Firm: Peacock; Deborah A. Oaxaca; Vidal
A. Peacock Myers, P.C.
Claims
What is claimed is:
1. A method wherein a supply of natural gas is fed into an absorber
wherein it is subjected to dry glycol to remove undesirable
materials therefrom so that the dry glycol is changed into wet
glycol that is removed from the absorber comprising: feeding wet
glycol from said absorber into a separator apparatus; collecting a
supply of wet glycol to a predetermined level in said separator
apparatus; feeding excess wet glycol greater than said
predetermined level from said separator apparatus to a reboiler for
changing said excess wet glycol into dry glycol and effluents;
feeding said effluents to a condenser apparatus; circulating wet
glycol from said supply of wet glycol through said condenser
apparatus to change said effluents to at least liquid water, liquid
hydrocarbons and uncondensed vapors and returning said circulating
wet glycol to said separator apparatus; feeding said at least
liquid water, liquid hydrocarbons and uncondensed vapors to a
liquid water removal separator apparatus; separating said liquid
water from said at least liquid water, liquid hydrocarbons and
uncondensed vapors; and feeding .[.said at least liquid
hydrocarbons and.]. said uncondensed vapors to said separator
apparatus.
2. A method as in claim 1 and further comprising: positioning an
eductor having an inlet port, an outlet port and a vacuum port
between said liquid water removal separator apparatus and said
separator apparatus; feeding said circulating wet glycol to said
inlet port; passing said circulating wet glycol through said
eductor and out of said outlet port to create a vacuum; feeding
said circulating wet glycol from said outlet port into said
separator apparatus; and connecting said vacuum port to said liquid
water removal separator apparatus to form a vacuum therein.
3. A method as in claim 2 and further comprising: forming at least
a first and a second chamber in said liquid water removal separator
apparatus; feeding said at least liquid water, liquid hydrocarbons
and uncondensed vapors into said first chamber; separating said at
least liquid water, said liquid hydrocarbons and uncondensed vapors
in said first chamber; removing said liquid hydrocarbons and said
uncondensed vapors from said first chamber and passing said removed
liquid hydrocarbons and said uncondensed vapors to said eductor;
transferring at least a portion of said liquid water from said
first chamber to said second chamber until said liquid water in
said second chamber reaches a predetermined level; and removing at
least a portion of said liquid water from said second chamber.
4. A method as in claim 3 and further comprising: providing at
least one gas emitting level control apparatus in at least said
absorber, said separator apparatus and said liquid water removal
separator apparatus; continuously collecting said gases emitted by
said gas emitting level control apparatus; and feeding said
continuously collected gases from said gas emitting level control
apparatus into said first chamber.
5. A method as in claim 1 and further comprising: forming a first
and a second chamber in said liquid water removal separator
apparatus; feeding said at least liquid water, liquid hydrocarbons
and uncondensed vapors into said first chamber; separating said at
least liquid water, said liquid hydrocarbons and uncondensed vapors
in said first chamber; removing said liquid hydrocarbons and said
uncondensed vapors from said first chamber; transferring at least a
portion of said liquid water from said first chamber to said second
chamber until said liquid water in said second chamber reaches a
predetermined level; and removing at least a portion of said liquid
water from said second chamber.
6. A method as in claim 5 and further comprising: providing at
least one gas emitting level control apparatus in at least said
absorber, said separator apparatus and said liquid water removal
separator apparatus; continuously collecting said gases emitted by
said gas emitting level control apparatus; and feeding said
continuously collected gases from said gas emitting level control
apparatus into said first chamber.
7. A method as in claim 1 and further comprising: providing at
least one gas emitting level control apparatus in at least said
absorber, said separator apparatus and said liquid water removal
separator apparatus; continuously collecting said gases emitted by
said gas emitting level control apparatus; and feeding said
continuously collected gases from said gas emitting level control
apparatus into said first chamber.
8. A natural gas dehydrator wherein a supply of natural gas is fed
into an absorber wherein it is subjected to dry glycol to remove
undesirable materials therefrom so that the dry glycol is changed
into wet glycol that is removed from the absorber comprising:
separator apparatus for receiving said wet glycol from said
absorber; said separator apparatus having structure for holding a
predetermined amount of said wet glycol; said separator apparatus
having additional structure for receiving excess wet glycol from
said structure; reboiler apparatus for receiving said excess wet
glycol and changing said excess wet glycol into dry glycol and
effluents; condenser apparatus for receiving said effluents;
circulating apparatus for circulating wet glycol from said
structure through said condenser apparatus to change said effluents
to at least liquid water, liquid hydrocarbons and uncondensed
vapors and returning said circulating wet glycol to said separator
apparatus; liquid water removal separator apparatus for receiving
said at least liquid water, liquid hydrocarbons and uncondensed
vapors and for separating and removing said liquid water; and
removing apparatus for removing said liquid hydrocarbons and said
uncondensed vapors from said liquid water removal separator
apparatus and feeding .[.said liquid hydrocarbons and.]. said
uncondensed vapors to said separator apparatus.
9. A natural gas dehydrator as in claim 8 wherein said removing
apparatus comprises: an eductor having an inlet port, an exit port
and a vacuum port; a first conduit through which said circulating
wet glycol flows connected to said inlet port; a second conduit
extending between said outlet port and said separator apparatus;
and a third conduit extending between said liquid water removal
separator apparatus and said vacuum port.
10. A natural gas dehydrator as in claim 9 wherein said liquid
water removal separator apparatus comprises: a hollow shell; a
partition in said hollow shell for forming at least a first and a
second chamber in said hollow shell; a first outlet port in said
first chamber; said third conduit being connected to said first
chamber for forming a vacuum therein; a first inlet port in said
first chamber so that said at least liquid water, liquid
hydrocarbons and uncondensed vapors can flow into said first
chamber and be separated into at least an upper layer comprising
said uncondensed vapors, a middle layer comprising said liquid
hydrocarbons and a lower layer comprising said liquid water; said
first outlet port being located so that said uncondensed vapors and
said liquid hydrocarbons flow through said first outlet port into
said third conduit; a second outlet port in said first chamber; a
second inlet port in said second chamber; a conduit connecting said
second outlet port and said second inlet port so that said liquid
water can flow from said first chamber into said second chamber;
and a drain port in said second chamber for draining said liquid
water from said second chamber.
11. A natural gas dehydrator as in claim 10 and further comprising:
at least one gas emitting level control apparatus in at least said
absorber, said separator apparatus and said liquid water removal
separator apparatus; a gas inlet port in said first chamber of said
liquid water removal separator apparatus; collecting apparatus for
collecting said gases emitted from said gas emitting level control
apparatus; and conduits extending between said collecting apparatus
and said gas inlet port for transmitting said gases to said gas
inlet port.
12. A natural gas dehydrator as in claim 8 wherein said liquid
water removal separator apparatus comprises: a hollow shell; a
partition in said hollow shell for forming at least a first and a
second chamber in said hollow shell; a first outlet port in said
first chamber; a first inlet port in said first chamber so that
said at least liquid water, liquid hydrocarbons and uncondensed
vapors can flow into said first chamber and be separated into at
least an upper layer comprising said uncondensed vapors, a middle
layer comprising said liquid hydrocarbons and a lower layer
comprising said liquid water; said first outlet port being located
so that said uncondensed vapors and said liquid hydrocarbons flow
through said first outlet port; a second outlet port in said first
chamber; a second inlet port in said second chamber; a conduit
connecting said second outlet port and said second inlet port so
that said liquid water can flow from said first chamber into said
second chamber; and a drain port in said second chamber for
draining said liquid water from said second chamber.
13. A natural gas dehydrator as in claim 12 and further comprising:
at least one gas emitting level control apparatus in at least said
absorber, said separator apparatus and said water separator
apparatus; a gas inlet port in said first chamber; collecting
apparatus for collecting said gases emitted from said gas emitting
level control apparatus; and conduits extending between said
collecting apparatus and said gas inlet port transmitting said
gases to said gas inlet port.
14. A natural gas dehydrator as in claim 8 and further comprising:
at least one gas emitting level control apparatus in at least said
absorber, said separator apparatus and said liquid water removal
separator apparatus; said liquid water removal separator apparatus
having at least a first chamber; a gas inlet port in said first
chamber; collecting apparatus for continuously collecting said
gases emitted from said gas emitting level control apparatus; and
conduits extending between said collecting apparatus and said gas
inlet port for transmitting said continuously collected gases to
said gas inlet port.
.Iadd.15. A desiccant regenerator system comprising: an absorber; a
separator apparatus linked directly to the absorber via a conduit,
said separator apparatus for receiving wet desiccant from the
absorber; a reboiler to change the wet desiccant into dry desiccant
and an effluent; a condenser apparatus for receiving the effluent
from said reboiler; and a liquid water removal separator apparatus
to receive at least liquid water, liquid hydrocarbons, and
uncondensed vapors from said condenser apparatus. .Iaddend.
.Iadd.16. The desiccant regenerator system of claim 15 wherein said
wet desiccant comprises wet glycol. .Iaddend.
.Iadd.17. The desiccant regenerator system of claim 15 wherein said
absorber changes dry desiccant into wet desiccant. .Iaddend.
.Iadd.18. The desiccant regenerator system of claim 17 further
comprising a dry desiccant storage unit that receives dry desiccant
from a reboiler and provides the dry desiccant to said absorber.
.Iaddend.
.Iadd.19. The desiccant regenerator system of claim 17 further
comprising a gas supply system for making contact with the dry
desiccant in said absorber, to change the dry desiccant into wet
desiccant. .Iaddend.
.Iadd.20. The desiccant regenerator system of claim 15 wherein said
condenser apparatus changes the effluent to at least liquid water,
liquid hydrocarbons, and uncondensed vapors. .Iaddend.
.Iadd.21. The desiccant regenerator system of claim 15 wherein said
condenser apparatus comprises a circulating apparatus for
circulating the wet desiccant through said condenser apparatus.
.Iaddend.
.Iadd.22. The desiccant regenerator system of claim 21 wherein said
circulating apparatus returns the wet desiccant to said separator
apparatus. .Iaddend.
.Iadd.23. The desiccant regenerator system of claim 15 wherein said
liquid water removal separator apparatus separates and removes
liquid water from the at least liquid water, liquid hydrocarbons,
and uncondensed vapors. .Iaddend.
.Iadd.24. The desiccant regenerator system of claim 23 further
comprising a removal apparatus disposed between said liquid water
removal separator apparatus and said separator apparatus for moving
hydrocarbon gases to said separator apparatus. .Iaddend.
.Iadd.25. The desiccant regenerator system of claim 24 wherein said
removal apparatus removes the uncondensed vapors from said liquid
water removal separator apparatus. .Iaddend.
.Iadd.26. The desiccant regenerator system of claim 24 wherein said
removal apparatus feeds the uncondensed vapors to said separator
apparatus. .Iaddend.
.Iadd.27. The desiccant regenerator system of claim 24 wherein said
removal apparatus comprises an eductor. .Iaddend.
.Iadd.28. The desiccant regenerator system of claim 27 wherein the
eductor further comprises an inlet port, an outlet port, and a
vacuum port. .Iaddend.
.Iadd.29. The desiccant regenerator system of claim 28 wherein said
removal apparatus comprises: a first conduit through which
circulating liquid desiccant flows connected to said inlet port; a
second conduit extending between said outlet port and said
separator apparatus; and a third conduit extending between said
liquid water removal separator apparatus and said vacuum port.
.Iaddend.
.Iadd.30. The desiccant regenerator system of claim 15 further
comprising a gas emitting level control apparatus in said separator
apparatus. .Iaddend.
.Iadd.31. The desiccant regenerator system of claim 15 further
comprising a gas emitting level control apparatus in said absorber.
.Iaddend.
.Iadd.32. A method of desiccant regeneration in a desiccant
regeneration system comprising the steps of: providing an absorber;
directly feeding liquid desiccant from the absorber into a
separator apparatus; collecting a supply of the liquid desiccant to
a level in the separator apparatus; feeding excess liquid desiccant
greater than the level in the separator apparatus from the
separator apparatus to a reboiler; changing the excess liquid
desiccant into dry desiccant and effluent; feeding the effluent to
a condenser apparatus; and changing the effluent in the condenser
apparatus to at least liquid water, liquid hydrocarbons, and
uncondensed vapors. .Iaddend.
.Iadd.33. The method of claim 32 further comprising the step of
discharging excess liquid desiccant over the level from the
separator apparatus. .Iaddend.
.Iadd.34. The method of claim 32 where the liquid desiccant
comprises wet glycol. .Iaddend.
.Iadd.35. The method of claim 32 further comprising the step of
obtaining the liquid desiccant to be fed into the separator
apparatus from the absorber. .Iaddend.
.Iadd.36. The method of claim 32 further comprising the step of
changing dry desiccant into wet desiccant in the absorber.
.Iaddend.
.Iadd.37. The method of claim 35 further comprising the steps of:
obtaining dry desiccant for the absorber from a dry desiccant
storage unit, said dry desiccant storage unit receiving the dry
desiccant from a reboiler; and changing the dry desiccant into wet
desiccant by contact with a gas in the absorber. .Iaddend.
.Iadd.38. The method of claim 37 where the gas comprises natural
gas. .Iaddend.
.Iadd.39. The method of claim 37 further comprising the step of
discharging dry gas from the absorber. .Iaddend.
.Iadd.40. The method of claim 32 wherein the step of collecting a
supply of liquid desiccant to a level in the separator apparatus
comprises collecting a supply of liquid desiccant to a
predetermined level. .Iaddend.
.Iadd.41. The method of claim 32 further comprising the step of
feeding the dry desiccant into a dry desiccant storage unit.
.Iaddend.
.Iadd.42. The method of claim 32 further comprising the step of
circulating liquid desiccant from the separator apparatus through a
condenser apparatus. .Iaddend.
.Iadd.43. The method of claim 32 further comprising the step of
returning liquid desiccant to the separator apparatus.
.Iaddend.
.Iadd.44. The method of claim 32 further comprising the step of
circulating liquid desiccant from the separator apparatus through
the condenser apparatus. .Iaddend.
.Iadd.45. The method of claim 32 further comprising the step of
returning the liquid desiccant to the separator apparatus.
.Iaddend.
.Iadd.46. The method of claim 32 further comprising the step of
feeding the at least liquid water, liquid hydrocarbons, and
uncondensed vapors to a liquid water removal separator apparatus.
.Iaddend.
.Iadd.47. The method of claim 46 further comprising the step of
separating liquid water from the at least water, liquid
hydrocarbons and uncondensed vapors in the liquid water removal
separator apparatus. .Iaddend.
.Iadd.48. The method of claim 47 further comprising the step of
discharging the liquid water. .Iaddend.
.Iadd.49. The method of claim 47 further comprising the step of
feeding the uncondensed vapors to the separator apparatus.
.Iaddend.
.Iadd.50. The method of claim 46 further comprising the step of
forming a first and second chamber in the liquid water removal
separator apparatus. .Iaddend.
.Iadd.51. The method of claim 50 further comprising the steps of:
feeding the at least liquid water, liquid hydrocarbons, and
uncondensed vapors into the first chamber; and separating the at
least liquid water, liquid hydrocarbons, and uncondensed vapors in
the first chamber. .Iaddend.
.Iadd.52. The method of claim 51 further comprising the steps of:
removing uncondensed vapors from the first chamber; and passing
uncondensed vapors to an eductor. .Iaddend.
.Iadd.53. The method of claim 52 further comprising the steps of:
transferring a portion of the liquid water from the first chamber
to the second chamber until the liquid water in the second chamber
reaches a level; and removing a portion of the liquid water from
the second chamber. .Iaddend.
.Iadd.54. The method of claim 32 further comprising the step of
providing at least one gas emitting level control apparatus in the
separator apparatus. .Iaddend.
.Iadd.55. The method of claim 33 further comprising the step of
providing at least one gas emitting level control apparatus in the
absorber. .Iaddend.
.Iadd.56. The method of claim 46 further comprising the step of
providing at least one gas emitting level control apparatus in the
liquid water removal separator apparatus. .Iaddend.
.Iadd.57. The method of claim 56 further comprising the steps of:
continuously collecting gases emitted by the gas emitting level
control apparatus; and feeding continuously collected gases from
the gas emitting level control apparatus into the liquid water
removal separator apparatus. .Iaddend.
.Iadd.58. A desiccant regenerator system comprising: an absorber; a
separator apparatus linked directly to the absorber via a conduit,
said separator apparatus for receiving wet desiccant from the
absorber; a reboiler to change the wet desiccant into dry desiccant
and an effluent; a condenser apparatus for receiving the effluent
from said reboiler; and a liquid water removal separator apparatus
comprising: a hollow shell; a partition in said hollow shell for
forming at least a first and a second chamber in said hollow shell;
a first outlet port in said first chamber; and an eductor in
fluidic connection with said first chamber to for forming a vacuum
therein. .Iaddend.
.Iadd.59. The desiccant regenerator system of claim 58 wherein said
liquid water removal separator apparatus further comprises a first
inlet port in said first chamber so that the at least liquid water,
liquid hydrocarbons, and uncondensed vapors can flow into said
first chamber. .Iaddend.
.Iadd.60. The desiccant regenerator system of claim 59 wherein the
at least liquid water, liquid hydrocarbons, and uncondensed vapors
separate into at least an upper layer comprising the uncondensed
vapors, a middle layer comprising liquid hydrocarbons, and a lower
layer comprising liquid water. .Iaddend.
.Iadd.61. The desiccant regenerator system of claim 60 wherein said
first outlet port is located so that the uncondensed vapors flow
through said first outlet port into said conduit. .Iaddend.
.Iadd.62. The desiccant regenerator system of claim 61 wherein said
liquid water removal separator apparatus further comprises: a
second outlet port in said first chamber; and a second inlet port
in said second chamber. .Iaddend.
.Iadd.63. The desiccant regenerator system of claim 62 wherein said
liquid water removal separator apparatus further comprises a
conduit connecting said second outlet port and said second inlet
port so that the liquid water can flow from said first chamber to
said second chamber. .Iaddend.
.Iadd.64. The desiccant regenerator system of claim 63 wherein said
liquid water removal separator apparatus further comprises a drain
port in said second chamber for draining liquid water from said
second chamber. .Iaddend.
.Iadd.65. A desiccant regenerator system comprising: an absorber; a
separator apparatus linked directly to the absorber via a conduit,
said separator apparatus for receiving wet desiccant from the
absorber; a reboiler to change the wet desiccant into dry desiccant
and an effluent; a condenser apparatus for receiving the effluent
from said reboiler; a liquid water removal separator apparatus; and
a gas emitting level control apparatus in said liquid water removal
separator, said gas emitting level control apparatus comprising: a
gas inlet port in a first chamber of said liquid water removal
separator apparatus; a collecting apparatus for collecting gases
emitted from said gas emitting level control apparatus; and
conduits extending between said collecting apparatus and said gas
inlet port that transmit gases to said gas inlet port.
.Iaddend.
.Iadd.66. The desiccant regenerator system of claim 65 further
comprising a level in said separator apparatus for the liquid
desiccant. .Iaddend.
.Iadd.67. The desiccant regenerator system of claim 66 further
comprising a discharge outlet for the excess liquid desiccant to be
discharged over said level. .Iaddend.
.Iadd.68. A method of desiccant regeneration in a desiccant
regeneration system comprising the steps of: providing an absorber;
directly feeding liquid desiccant from the absorber into a
separator apparatus; and disposing an eductor between a liquid
water removal separator apparatus and the separator apparatus to
move hydrocarbon gases and liquid desiccant from the liquid water
removal separator apparatus to the separator apparatus.
.Iaddend.
.Iadd.69. The method of claim 68 further comprising the step of
providing the eductor with an inlet port, an outlet port, and a
vacuum port. .Iaddend.
.Iadd.70. The method of claim 69 further comprising the steps of:
feeding circulating liquid desiccant through the inlet port; and
passing circulating liquid desiccant through the eductor and out of
the outlet port to create a vacuum. .Iaddend.
.Iadd.71. The method of claim 70 further comprising the step of
feeding circulating liquid desiccant from the outlet port into the
separator apparatus. .Iaddend.
.Iadd.72. The method of claim 70 further comprising the step of
connecting the vacuum port to the liquid water removal separator
apparatus to form a vacuum therein. .Iaddend.
Description
FIELD OF THE INVENTION
This invention relates generally to natural gas dehydrators of the
type used to remove water and water vapor from a natural gas stream
composed of a mixture of natural gas, liquid hydrocarbons, water
and water vapors and is particularly directed to field natural gas
dehydrators.
BACKGROUND OF THE INVENTION
An example of such a field natural gas dehydrator is disclosed in
U.S. Pat. No. 5,766,313 to Rodney Thomas Health and the disclosure
therein is specifically incorporated herein by reference thereto.
In general, such systems comprise a separator means for receiving
the oil and water liquids from "wet" (water vapor laden) gas; and a
water absorber means, which employs a liquid dehydrating agent such
as glycol, for removing the water vapor from the wet gas and
producing "dry" gas suitable for commercial usage. The glycol is
continuously supplied by a pump to the absorber means in a "dry"
low-water vapor-pressure condition and is removed from the absorber
means in a "wet" high-water vapor-pressure condition. The wet
glycol is continuously removed from the absorber means and
circulated through a reboiler means, which includes a still column,
for removing the absorbed water from the glycol and heating the
glycol to provide a new supply of hot dry glycol. Heating of the
glycol in the reboiler means is generally accomplished through use
of a gas burner mounted in a fire tube. The hot dry glycol from the
reboiler means passes through a heat exchanger, where the hot dry
glycol transfers some of its heat to incoming wet glycol going to
the still column. The dry glycol subsequently passes to a dry
glycol storage tank. A glycol passage means is provided to enable
passage of wet glycol from the absorber means to the reboiler means
and to pump dry glycol from the storage tank to the absorber
means.
Besides water, the wet glycol going to the still column of the
reboiler of the natural gas dehydrator will contain natural gas and
absorbed hydrocarbons. A large part of the natural gas flowing with
the wet glycol to the still column is the natural gas required to
power the glycol pump. The balance of the natural gas and other
hydrocarbons are absorbed or entrained into the glycol during the
water-absorption step in the absorber means.
On many dehydrators, a volume of natural gas is intentionally
induced into the reboiler in order to dry the wet glycol to a
higher concentration than can be accomplished by simply adding
heat. The process of intentionally inducing a volume of natural gas
into the reboiler is referred to as gas stripping.
In the still column of the reboiler of the natural gas dehydrator,
the water, natural gas, and other hydrocarbons are separated from
the glycol by the pressure reduction from the absorber pressure to
approximately atmospheric pressure in the still column and by the
application of heat from the burner in the fire tube of the
reboiler.
The water, natural gas, and other hydrocarbons contained in the wet
glycol stream which are separated in the still column from the wet
glycol will be exhausted into the atmosphere through the
atmospheric vent on the still column. The hydrocarbon vapors
released through the still column of a natural gas dehydrator are
air pollutants. Specifically, certain hydrocarbons such as benzene,
toluene, ethylbenzene, and xylene, commonly referred to as BTEX
have been proven to be carcinogenic.
The gas dehydrator disclosed in U.S. Pat. No. 5,766,313 offers
solutions to the problems discussed above but improvements can be
made to such a gas dehydrator.
BRIEF DESCRIPTION OF THE INVENTION
This invention provides a field natural gas dehydrator in which the
wet glycol from the absorber is fed into a three phase emissions
separator which is provided with suitable apparatus, such as an
overflow tank, that collects an amount of the wet glycol, for a
purpose described more fully below, and then routes any additional
amount of wet glycol to a reboiler. The collected wet glycol is
used as a circulating medium to cool the emissions from the still
column of a reboiler and to provide the energy for an educator as
described more fully below. By using the collected wet glycol as
the pump circulating medium, the lubricity, vapor pressure,
viscosity, and etc. of the circulating medium remain relatively
constant from dehydrator to dehydrator; therefore overcoming
potential pump problems which could occur if a circulating medium
with changing physical constants, from dehydrator to dehydrator,
was used.
Also, the collected wet glycol can be pumped in greater volumes to
be used as a heat exchange medium for condensing the effluents from
the still column of the reboiler. As explained more fully below,
the volume of the collected wet glycol being pumped by the
circulating pump is 20 to 30 times greater than the volume of the
wet glycol exiting the absorber.
This invention also provides a liquid water removal separator that
collects the liquid water condensed from the effluents from the
still column so that substantially no liquid water is entered into
the emissions separator.
The invention also provides a system for collecting the gases from
the level controllers used in the natural gas dehydrator so that
the collected gases may be used as fuel for the burner of the
reboiler.
In accordance with this invention, a natural gas dehydrator is
provided wherein a supply of natural gas is fed into an absorber
wherein it is subjected to dry glycol to remove undesirable
materials therefrom so that the dry glycol is changed into wet
glycol that is removed from the absorber and fed at reduced
pressure into a three phase emissions separator apparatus. One part
of the three phase emissions separator apparatus has structure for
holding a predetermined amount of the wet glycol. The three phase
emissions separator apparatus has additional structure for
receiving excess wet glycol from the structure. A reboiler
apparatus receives the excess wet glycol and changes the excess wet
glycol into dry glycol and effluents. A condenser apparatus is
provided for receiving the effluents. Circulating apparatus is
provided for circulating wet glycol from the structure through the
condenser apparatus to change the effluents to at least liquid
water, liquid hydrocarbons and uncondensed vapors and returning the
circulating wet glycol to the three phase emissions separator
apparatus. Liquid water removal separator apparatus is provided for
receiving that at least liquid water, liquid hydrocarbons and
uncondensed vapors for separating and removing the liquid water.
Additional apparatus is provided for removing the liquid
hydrocarbons and the uncondensed vapors from the liquid water
removal separator apparatus and feeding the liquid hydrocarbons and
the uncondensed vapors to the three phase emissions separator
apparatus.
The additional apparatus comprises an eductor having an inlet port,
and exit port and a vacuum port. A first conduit through which the
circulating wet glycol flows is connected to the inlet port. A
second conduit extends between the outlet port and the three phase
emissions separator apparatus. A third conduit extends between the
liquid water removal separator apparatus and the vacuum port to
form a vacuum in the liquid water removal separator apparatus.
The liquid water removal separator apparatus comprises a hollow
shell having a partition therein for forming at least a first and a
second chamber in the hollow shell. A first outlet port is formed
in the first chamber and is connected to the third conduit so that
a vacuum is formed in the first chamber. A first inlet port is
formed in the first chamber so that the at least liquid water,
liquid hydrocarbons and uncondensed vapors from the condenser
apparatus can flow into the first chamber and be separated into at
least an upper layer comprising the uncondensed vapors, a middle
layer comprising the liquid hydrocarbons and a lower layer
comprising the liquid water. The first outlet port is located so
that the uncondensed vapors and the liquid hydrocarbons can flow
through the first outlet port into the third conduit. The withdrawn
uncondensed vapors and the liquid hydrocarbons enter the eductor
and are entrained into the wet glycol and flow with the wet glycol
from the eductor to the three phase emissions separator. A second
outlet port is formed in the first chamber and a second inlet port
is formed in the second chamber. A conduit connects the second
outlet port and the second inlet port so that the liquid water can
flow from the first chamber into the second chamber. A drain port
is formed in the second chamber for draining the liquid water from
the second chamber.
The natural gas dehydrator has at least one gas emitting level
control apparatus in at lest the absorber, the three phase
emissions separator apparatus and the liquid water removal
separator apparatus. A gas inlet port is formed in the liquid water
removal separator apparatus. Collecting apparatus is provided for
collecting the gases emitted from the gas emitting level control
apparatus and conduits extend between the collecting apparatus and
the gas inlet port for transmitting the gases to the gas inlet
port.
In the operation of the above-described apparatus a supply of
natural gas is fed into an absorber wherein it is subjected to dry
glycol to remove undesirable materials therefrom so that the dry
glycol is changed into wet glycol that is removed from the absorber
and is processed by feeding the wet glycol from the absorber into
the three phase emissions separator apparatus; collecting a supply
of wet glycol to a predetermined level in the three phase emissions
separator apparatus; feeding excess wet glycol greater than the
predetermined level from the three phase emissions separator
apparatus to a reboiler for changing the excess wet glycol into dry
glycol and effluents; feeding the effluents to a condenser
apparatus; circulating wet glycol from the supply of wet glycol
through the condenser apparatus to change the effluents to at least
liquid water, liquid hydrocarbons and uncondensed vapors and
returning the circulating wet glycol to the three phase emissions
separator apparatus; feeding the at least liquid water, liquid
hydrocarbons and uncondensed vapors to a liquid water removal
separator apparatus; separating and removing the liquid water from
the at least liquid water, liquid hydrocarbons and uncondensed
vapors; draining the removed liquid water; and feeding the at least
liquid hydrocarbons and the uncondensed vapors to the three phase
emissions separator apparatus.
A vacuum is formed in the liquid water removal separator apparatus
by positioning an educator having an inlet port, an outlet port and
a vacuum port between the liquid water removal separator apparatus
and the three phase emissions separator apparatus; feeding the
circulating wet glycol to the inlet port; passing the circulating
wet glycol through the eductor and out of the outlet port to create
a vacuum; feeding the circulating wet glycol from the outlet port
into the three phase emissions separator apparatus; and connecting
the vacuum port to the liquid water removal separator apparatus to
form a vacuum therein.
The removal of the liquid water is accomplished by forming a first
and a second chamber in the liquid water removal separator
apparatus; feeding the at least liquid water, liquid hydrocarbons
and uncondensed vapors into the first chamber; separating the at
least liquid water, the liquid hydrocarbons and uncondensed vapors
in the first chamber; removing the liquid hydrocarbons and the
uncondensed vapors from the first chamber; entraining the removed
uncondensed vapors and liquid hydrocarbon; into the wet glycol in
the eductor; transferring at least a portion of the liquid water
from the first chamber to the second chamber until the liquid water
in the second chamber reaches a predetermined level; and removing
at least a portion of the liquid water from the second chamber.
Additional gas is transferred to the first chamber by providing at
least one gas emitting level control apparatus in at least the
absorber, the three phase emissions separator apparatus and the
liquid water removal separator apparatus; collecting the gases
emitted by the gas emitting level control apparatus; and feeding
the collected gases into the first chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are illustrated in the
drawings in which:
FIG. 1 is a block diagram of the invention;
FIG. 2 is a schematic elevational view of the liquid water removal
separator apparatus;
FIG. 3 is a schematic elevational view similar to FIG. 2 with parts
removed;
FIG. 4 is a schematic end elevational view of parts of FIG. 3;
and
FIG. 5 is a schematic end elevational view taken from the right
side of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
This invention is directed toward a field natural gas dehydrator
such as the one described in U.S. Pat. No. 5,766,313, the
disclosure of which is specifically incorporated herein by
reference thereto. The volume and pressure of the natural gas
flowing through the system can vary in wide ranges. Each unit is
designed by those skilled in the art to perform at wide ranges of
volume and pressure of the natural gas being processed and various
controls have been associated with the natural gas dehydrators so
that these dehydrators can be operated in a conventional manner by
those skilled in the art. The operation of the various portions of
this invention uses such conventional apparatus that are normally
used in the operation of a natural gas dehydrator. In accordance
with this invention, the natural gas is first passed through a
conventional three phase inlet separator (not shown) to remove
water and liquid hydrocarbons therefrom. The natural gas is then
fed into an absorber 2 through an inlet 4 so that the natural gas
can flow upwardly through the absorber. Dry glycol is introduced
through inlet 6 and flows through spaced apart bubble trays (not
shown) into the absorber and then downwardly through the absorber.
The dry glycol functions primarily to remove water and hydrocarbons
from the natural gas and becomes wet glycol. The treated natural
gas exits through outlet 8 in the top portion of the absorber 2 and
is passed through a glycol-gas heat exchanger 10 and passes out as
dry salable natural gas at relatively high pressures, for example
50 PSIG to 1500 PSIG depending on the operating pressures of the
pipeline system.
The wet glycol is collected in a wet glycol sump 12 in the bottom
portion of the absorber 2 and flows to the inlet port 14 of a
conventional three phase emissions separator 16. Free gaseous
hydrocarbons contained in the wet glycol will be released in the
three phase emissions separator as a result of the reduction of
pressure form the pressure of the absorber of between about 50 and
1500 PSIG to the pressure of the three phase emissions separator
which is between about 10 and 15 PSIG and preferably about 15 PSIG.
This is accomplished by conventional apparatus. Liquid hydrocarbons
are separated from the wet glycol in the three phase emissions
separator 16 by a weir system and are withdrawn through outlet 18.
The wet glycol is collected in one part of the three phase
emissions separator 16 to a predetermined level and then the excess
wet glycol flows to another part of the three phase emissions
separator. The flow of the wet glycol from the absorber to the
three phase emissions separator is controlled by the amount of dry
glycol required to remove the water vapor from the natural gas
being processed. The amount of dry glycol used in the range of 3 to
6 gallons of dry glycol for each pound of water removed.
The freed gaseous hydrocarbons exit through outlet 20 in the top
portion of the three phase emissions separator 16 and flow thorough
conduit 21 into a system 22 as described in the '313 patent to be
used as fuel in a reboiler 24 as described more fully below.
Once the predetermined level of wet glycol has been reached in the
three phase emissions separator 16, any additional wet glycol
passes from the three phase emissions separator 16 through pipe 26
and then through a rolled coil 27 in the dry glycol storage 28 and
then thorough pipe 26 to the still column 30 of the reboiler 24
wherein the wet glycol is changed into dry glycol and fed through
line 32 into the dry glycol storage 28. The effluents from the
still column, liquid water, liquid hydrocarbons, vaporized water,
gases and vaporized hydrocarbons are processed as described more
fully below.
Wet glycol is withdrawn from the predetermined level of wet glycol
in the three phase emissions separator 16 through outlet 34 and
enters a pump 36 which circulates the wet glycol through
transmission lines through a particulate filter 38 and a
hydrocarbon filter 40 and into an effluent condenser 42. On one of
the smallest units the pump circulates the wet glycol at the rate
of between about 4 and 6 gallons/min and preferably at about 5
gallons/min and at a pressure of between about 40 and 100 PSIG and
preferably at a pressure of about 45 PSIG. On larger units the flow
will be larger but the pressures will generally remain the same.
The effluent condenser 42 comprises a hollow shell 43 having a
finned tubing 45 located therein. The effluents from the still
column 30 flow through piping 46 and enter into the finned tubing
45. The wet glycol enters at one end 44 of the effluent condenser
42 and flows around the finned tubing 45. The wet glycol functions
to cool the effluents in the finned tubing 45. Using the wet glycol
circulating as described above greatly increases the cooling
efficiency of the effluent condenser. The amount of wet glycol
circulating through the condenser system is substantially greater
than the amount of wet glycol exiting from the absorber 2 and is
about 20 to 30 times greater than the amount of wet glycol exiting
from the absorber 2. The wet glycol then flows through outlet 38 of
the effluent condenser 42 through suitable piping and flows through
a conduit 49 in a liquid water removal separator 50 and through
line 51 into the power inlet port of a conventional eductor 52 for
creating a vacuum source that forms a vacuum in the liquid water
removal separator 50 for purposes described more fully below. The
wet glycol flows out of the eductor 52 and is passed into the three
phase emissions separator 16 through line 54.
The cooled effluent flows out of the effluent condenser 42 through
line 60 and enters the liquid water removal separator 50 wherein
water is removed as described below through drain 62. The system
for removing the water is discussed more fully below. Hydrocarbon
vapors and any unseparated liquid water and liquid hydrocarbons are
drawn out of the liquid water removal separator 50 by the vacuum in
the eductor 52 through line 64 and enter into the eductor and are
entrained into the wet glycol in the eductor and move with the wet
glycol into the three phase emissions separator 16 through line 54.
The hydrocarbon vapors in the three phase emissions separator 16
flow out thereof as described above, the wet glycol flows into the
still column as described above or is used to maintain the wet
glycol level in the three phase emissions separator 16. If any
liquid hydrocarbon is formed in the three phase emissions
separator, it is removed therefrom through outlet 18.
The dry glycol for the absorber 2 is drawing from the dry glycol
storage 28 through line 64 and flows through the glycol gas heat
exchanger 10 and enters a suitable pump 66 to enter the absorber 2
through inlet 6.
The hydrocarbon vapors leaving the tree phase emissions separator
are fed into a system 22 wherein the hydrocarbon vapors alone or in
conjunction with a supplemental fuel source are used to fire the
burner 68 in the reboiler. The wet glycol entering the still column
of the reboiler is dried and exits from the reboiler into a dry
glycol storage tank through line 32. This system 22 is similar to
that disclosed in U.S. Pat. No. 5,766,313.
The absorber 2 has a level control apparatus 70, the emissions
separator has two level controls apparatus 72 and 74 and the liquid
water removal separator 50 has a level control apparatus 76. Each
of the level control apparatus 70, 72, 74 and 76 emit a gas during
operation and are of the type marketed by .[.Wellmack.].
.Iadd.Wellmark .Iaddend.Company under the trade designation liquid
level control. The emitted gases are collected from each level
control apparatus and are fed through inlet port 140 into the
chamber 106 (FIG. 3) of the liquid water removal separator 102. The
gas from level control apparatus 70 is fed through conduit 78; the
gas from level control apparatus 72 and 74 are fed through conduit
80 and the gas from level control apparatus 76 is fed through
conduit 82 to the inlet port 140. Eventually, these gases flow from
the three phase emissions separator 16 through conduit 21 to the
system 22 to be used as fuel for the burner 68.
The water removing system is illustrated in FIGS. 2-5. The cooling
of the effluents in the effluent condenser 42 changes the effluents
from water vapor to liquid water and hydrocarbon vapors to liquid
hydrocarbons and some uncondensed vapors. The uncondensed vapors,
the liquid water and liquid hydrocarbons flow under a slight vacuum
in the liquid water removal separator 50 (4 to 6 inches water
column) from the effluent condenser 42 through conduit 60 to the
inlet 100 of the liquid water removal separator apparatus 102. The
liquid water removal separator apparatus 102 lies generally in a
horizontal plane and has a generally cylindrical interior and has a
sealed baffle 104 to divide the liquid water removal separator
apparatus 102 into two chambers 106 and 108. The chamber 106 has a
generally vertically extending pipe 110 which is open at the top
112 and bottom 114. The pipe 110 has an open port 116 located
below, approximately one inch, the outlet 118 of the liquid water
removal separator apparatus 102. Open port 116 is connected by pipe
120 to outlet pipe 122 in the shell 124 of the liquid water removal
separator apparatus 102. The chamber 108 has an inlet port 126, a
liquid water control connection 128, a liquid water outlet port 130
and a pressure supply port 132.
The effluent from the effluent condenser 42 enters into the chamber
106 which is at the same pressure as leaving the effluent condenser
42. The liquid hydrocarbons, gaseous hydrocarbons, uncondensed
water vapor and any unseparated liquid water flow out of the
chamber 106 through outlet 118 and through line 64 (FIG. 1) to the
vacuum port 134 of the eductor 52 where they are entrained into the
wet glycol flowing through the eductor 52. The liquid water and the
liquid hydrocarbons contained in the effluent are collected in the
chamber 106 and are separated by gravity. The liquid hydrocarbons
rise to the top and exit through outlet 118 and flow with the
gaseous components to the vacuum port 134 of the eductor 52. The
liquid water settles to the bottom and flow sunder the bottom 114
of the pipe 110 and up thorough the pipe 110. The liquid water then
flows through pipe 120 to the outlet pipe 122. A conduit 136 (FIG.
2) having a normally open motor valve mounted therein connects
outlet pipe 122 to the inlet port 126. The liquid water flows from
outlet pipe 122 through conduit 136 and into the chamber 108
through the inlet port 126. The chamber 108 has the same vacuum as
the chamber 106. When the water level in the chamber 108 reaches a
predetermined high level set point, the level control apparatus
(not shown) but inserted through the connection 128 puts out a gas
signal to open a water dump valve (not shown) and to close the
normally open motor valve in the conduit 136. The gas signal also
energizes pressure supply port 132 to pressurize chamber 108 to
above atmospheric pressure and cause the liquid water to flow out
of the chamber 108 through liquid water outlet port 130. When the
liquid water level in the chamber 108 reaches a predetermined low
level, the level control apparatus vents off the pressure, opens
the motor valve in the conduit 136 and closes the water dump valve.
When the motor valve in the conduit 136 opens, the gas under
pressure flows through the inlet 126 through the conduit 136 and
the outlet pipe 122 and out thorough the top 112 of pipe 110 into
the chamber 106 and is withdrawn from the chamber 106 by the vacuum
of the eductor 52 so that the vacuum pressure is equalized in the
chambers 106 and 108. The liquid water then again begins to flow
into the chamber 108. The liquid water removal separator 102 is
provided with a drain port 142 for the chamber 106 and a drain port
144 for the chamber 108. Also, heating apparatus 146 is provided in
the liquid water removal separator 102.
While an illustrative and presently preferred embodiment of the
invention has been described in detail herein, it is to be
understood that the inventive concepts may be otherwise variously
embodied and employed and that the appended claims are intended to
be construed to include such variations except insofar as limited
by the prior art.
* * * * *