U.S. patent application number 13/005756 was filed with the patent office on 2012-07-19 for water recovery system for a cooling tower.
This patent application is currently assigned to General Electric Company. Invention is credited to Harish Chandra Dhingra, Donald Gordon Laing, Andrew Philip Shapiro, Ching Jen Tang.
Application Number | 20120180512 13/005756 |
Document ID | / |
Family ID | 45495767 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120180512 |
Kind Code |
A1 |
Laing; Donald Gordon ; et
al. |
July 19, 2012 |
WATER RECOVERY SYSTEM FOR A COOLING TOWER
Abstract
A water recovery system for a cooling tower includes an
intercooler having a first circuit portion and a second circuit
portion. The first circuit portion is configured and disposed to
receive a liquid desiccant and the second circuit portion is
configured and disposed to receive coolant. A flash drum includes
an inlet connected to the first circuit portion, a vapor outlet and
a liquid desiccant outlet. A condenser is fluidly coupled to the
vapor outlet of the flash drum. The condenser includes a condensate
outlet. A cooling tower is fluidly connected to the liquid
desiccant outlet of the flash drum and the condenser. The cooling
tower includes a water stripper having a collector member, and a
heat exchanger arranged below the water stripper. The collector
member is configured to receive water laden liquid desiccant and
the heat exchanger is configured and disposed to receive make-up
water from the condenser.
Inventors: |
Laing; Donald Gordon;
(Houston, TX) ; Dhingra; Harish Chandra;
(Friendswood, TX) ; Shapiro; Andrew Philip;
(Schenectady, NY) ; Tang; Ching Jen; (Watervliet,
NY) |
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
45495767 |
Appl. No.: |
13/005756 |
Filed: |
January 13, 2011 |
Current U.S.
Class: |
62/238.6 ;
62/305; 62/94 |
Current CPC
Class: |
F02C 6/18 20130101; F01K
9/003 20130101; F01K 23/10 20130101; F02C 7/143 20130101; F02C 7/16
20130101; F05D 2260/211 20130101 |
Class at
Publication: |
62/238.6 ;
62/305; 62/94 |
International
Class: |
F25B 27/00 20060101
F25B027/00; F25D 17/06 20060101 F25D017/06; F28D 5/00 20060101
F28D005/00 |
Claims
1. A water recovery system for a cooling tower, the water recovery
system comprising: an intercooler member including a first circuit
portion and a second circuit portion, the first circuit portion
configured and disposed to receive a liquid desiccant and the
second circuit portion being configured and disposed to receive
coolant; a flash drum including an inlet fluidly connected to the
first circuit portion, a vapor outlet and a liquid desiccant
outlet; a condenser fluidly coupled to the vapor outlet of the
flash drum, the condenser including a condensate outlet; and a
cooling tower fluidly connected to the liquid desiccant outlet of
the flash drum and the condenser, the cooling tower including a
water stripper having a collector member, and a heat exchanger
arranged below the water stripper, the collector member being
configured and disposed to receive water laden liquid desiccant and
the heat exchanger being configured and disposed to receive make-up
water from the condenser.
2. The water recovery system according to claim 1, further
comprising: a heat exchanger fluidly connected between the
desiccant outlet of the flash drum and the water stripper, the heat
exchanger being configured and disposed to lower a temperature of
liquid desiccant flowing from the flash drum to the water
stripper.
3. The water recovery system according to claim 1, wherein the
first circuit portion is fluidly isolated from the second circuit
portion in the intercooler.
4. The water recovery system according to claim 1, further
comprising: a desiccant spray member arranged in the water
stripper, the desiccant spray member being fluidly coupled to the
liquid desiccant outlet of the flash drum.
5. The water recovery system according to claim 1, further
comprising: a water spray member arranged in the water stripper,
the water spray member being fluidly coupled to the condensate
outlet of the condenser.
6. The water recovery system according to claim 5, wherein the
water spray member directs the make-up water onto the heat
exchanger.
7. The water recovery system according to claim 1, wherein the
collector member is fluidly connected to the first circuit
portion.
8. The water recovery system according to claim 1, wherein the heat
exchanger is fluidly connected to the second circuit portion.
9. A turbomachine system comprising: a first turbomachine section
including an extraction outlet; a second turbomachine section
including an extraction inlet fluidly connected to the extraction
outlet of the first turbomachine section; and a water recovery
system operatively connected to the turbomachine system, the water
recovery system comprising: an intercooler member including a first
circuit portion and a second circuit portion, the first circuit
portion being configured and disposed to receive a liquid desiccant
and the second circuit portion being configured and disposed to
receive coolant, the intercooler member being configured and
disposed to remove heat from an extraction fluid passing from the
extraction outlet; a flash drum including an inlet fluidly
connected to the first circuit portion, a vapor outlet and a liquid
desiccant outlet; a condenser fluidly coupled to the vapor outlet
of the flash drum; and a cooling tower fluidly connected to the
liquid desiccant outlet of the flash drum and the condenser, the
cooling tower including a water stripper having a collector member,
and a heat exchange member arranged below the water stripper, the
collector member being configured and disposed to receive water
laden liquid desiccant and the heat exchanger being configured and
disposed to receive water from the condenser.
10. The turbomachine system according to claim 9, further
comprising: a heat exchanger fluidly connected between the liquid
desiccant outlet of the flash drum and the water stripper, the heat
exchanger being configured and disposed to lower a temperature of
liquid desiccant flowing from the flash drum to the water
stripper.
11. The turbomachine system according to claim 9, wherein the first
circuit portion is fluidly isolated from the second circuit portion
in the intercooler.
12. The turbomachine system according to claim 9, further
comprising: a desiccant spray member arranged in the water
stripper, the desiccant spray member being fluidly coupled to the
liquid desiccant outlet of the flash drum.
13. The turbomachine system according to claim 9, further
comprising: a water spray member arranged in the water stripper,
the water spray member being fluidly coupled to the vapor outlet of
the flash drum.
14. The turbomachine system according to claim 9, wherein the
collector member is fluidly connected to the first circuit
portion.
15. The turbomachine system according to claim 9, wherein the heat
exchanger is fluidly connected to the second circuit portion.
16. A method of extracting water from vapor emitted by a cooling
tower, the method comprising: passing a water laden liquid
desiccant though an intercooler; absorbing heat into the water
laden liquid desiccant forming a heat laden liquid desiccant;
directing the heat laden liquid desiccant through a flash drum;
extracting water vapor from the heat laden liquid desiccant in the
flash drum forming a substantially water free liquid desiccant;
introducing the substantially water free liquid desiccant into wet
air in the cooling tower; absorbing water from the wet air into the
substantially water free liquid desiccant forming a water laden
liquid desiccant; and passing the water laden liquid desiccant back
into the intercooler.
17. The method of claim 16, further comprising: collecting the
water laden liquid desiccant in a collector arranged in the water
stripper portion of the cooling tower.
18. The method of claim 16, wherein introducing the substantially
water free liquid desiccant into the wet air comprises spraying the
substantially water free liquid desiccant into the wet air.
19. The method of claim 16, further comprising: passing the water
vapor from the flash drum to a condenser to form liquid water.
20. The method of claim 19, further comprising: spraying the liquid
water onto a heat exchanger in the cooling tower.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to cooling
towers and, more particularly, to a water recovery system for a
cooling tower.
[0002] Turbomachines operate at high pressures. In order to enhance
operation in applications such as power generation and mechanical
drive gas turbines many turbomachines employ intercoolers that are
configured to lower compressed air temperature between compressor
stages. Conventional systems for lowering the temperature of the
compressed air include both dry and wet cooling systems.
[0003] In a dry cooling system, heat is transferred from the
extraction air into cooling water that circulates through heat
transfer plates or tubes having heat transfer surfaces. After
absorbing heat, the cooling water is passed to a dry cooling tower
and guided over additional heat transfer plates or tubes before
being re-circulated to cool the extraction air. In a wet cooling
system, after absorbing heat from the extraction air, the cooling
water is passed to a cooling tower. In the cooling tower, the
cooling water is brought into thermally conductive contact with
air. The air extracts heat from the cooling water creating a plume
or vapor. The cooling water is passed back to exchange heat with
the extraction air, and the plume is passed to ambient. In an
alternative wet cooling system, water is sprayed onto heat transfer
plates or tubes such as employed in the dry system to further cool
closed loop cooling water. The closed loop cooling water is passed
back to exchange heat with the extraction air and the plume is
passed to ambient. Often times, such as in very dry environments or
where water is not in abundance, it is desirable to extract water
from the plume.
BRIEF DESCRIPTION OF THE INVENTION
[0004] According to one aspect of the invention, a water recovery
system for a cooling tower includes an intercooler member having a
first circuit portion and a second circuit portion. The first
circuit portion is configured and disposed to receive a liquid
desiccant and the second circuit portion is configured and disposed
to receive coolant. A flash drum includes an inlet fluidly
connected to the first circuit portion, a vapor outlet and a liquid
desiccant outlet. A condenser is fluidly coupled to the vapor
outlet of the flash drum. The condenser includes a condensate
outlet. A cooling tower is fluidly connected to the liquid
desiccant outlet of the flash drum and the condenser. The cooling
tower includes a water stripper having a collector member, and a
cooler arranged below the water stripper. The collector member is
configured and disposed to receive water laden liquid desiccant and
the cooler is configured and disposed to receive make-up water from
the condenser.
[0005] According to another aspect of the invention, a turbomachine
system includes a first turbomachine section including an
extraction outlet, a second turbomachine section including an
extraction inlet fluidly connected to the extraction outlet of the
first turbomachine section, and a water recovery system operatively
connected to the turbomachine system. The water recovery system
includes an intercooler member having a first circuit portion and a
second circuit portion. The first circuit portion is configured and
disposed to receive a liquid desiccant and the second circuit
portion is configured and disposed to receive coolant. The
intercooler member is configured and disposed to remove heat from
an extraction fluid passing from the extraction outlet. A flash
drum includes an inlet fluidly connected to the first circuit
portion, a vapor outlet and a liquid desiccant outlet. A condenser
is fluidly coupled to the vapor outlet of the flash drum. A cooling
tower is fluidly connected to the liquid desiccant outlet of the
flash drum and the condenser. The cooling tower includes a water
stripper having a collector member, and a cooler arranged below the
water stripper. The collector member is configured and disposed to
receive water laden liquid desiccant and the cooler is configured
and disposed to receive water from the condenser.
[0006] According to yet another aspect of the invention, a method
of extracting water from vapor emitted by a cooling tower includes
passing a water laden liquid desiccant though an intercooler,
absorbing heat into the water laden liquid desiccant forming a heat
laden liquid desiccant, directing the heat laden liquid desiccant
through a flash drum, extracting water vapor from the heat laden
liquid desiccant in the flash drum forming a substantially water
free liquid desiccant, introducing the substantially water free
liquid desiccant into wet air in the cooling tower, absorbing water
from the wet air into the substantially water free liquid desiccant
forming a water laden liquid desiccant, and passing the water laden
liquid desiccant back into the intercooler.
[0007] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0008] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0009] The FIGURE is a schematic diagram of a turbomachine system
including a system for recovering water from a cooling tower in
accordance with an exemplary embodiment.
[0010] The detailed description explains embodiments of the
invention, together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0011] As best shown in the FIGURE, a turbomachine system in
accordance with an exemplary embodiment is indicated generally at
2. Turbomachine system 2 includes a first compressor section 4
operatively connected to a second compressor section 6. Second
compressor section 6 is fluidly connected to a turbine section 8
via combustor 10. First and second compressor sections 4 and 6 are
operatively connected to turbine section 8 through a common
compressor/turbine shaft 12. First compressor section 4 includes an
inlet 15 that receives air through an intake 16. First compressor
section 4 also includes an extraction air outlet 18 that delivers
extraction air 19 to an extraction air inlet 20 on second
compressor section 6. Second compressor section 6 is also shown to
include an outlet 22 that is fluidly connected to combustor 10.
Turbine section 8 is shown to include an inlet 24 that is fluidly
connected to a combustor outlet (not separately labeled) and an
outlet or exhaust 26 that leads to an exhaust stack 30. In
accordance with the exemplary embodiment shown, heat is removed
from extraction air 19 prior to introduction into extraction air
inlet 20. The heat is removed by a water recovery system 40, which,
as will be discussed more fully below, in addition to recovering
water from cooling tower vapor, also lowers a temperature of
extraction air flowing between first and second compressor sections
4 and 6.
[0012] As shown, water recovery system 40 includes a primary or
intercooler 44 having a first circuit portion 46 and a second
circuit portion 48 that lead to a cooling tower 50 having a water
stripper or absorber 52. Water stripper 52 strips or absorbs
moisture contained in the air passing through the cooling tower 50.
As will be discussed more fully below, first circuit portion 46 is
fluidly isolated from second circuit portion 48 in intercooler 44.
First and second circuit portions 46 and 48 are fluidly connected
to cooling tower 50. First circuit portion 46 includes a liquid
desiccant that is in a heat exchange relationship with extraction
air 19. As will become more readily apparent below, the liquid
desiccant is configured to remove moisture from vapor passing from
cooling tower 50. In accordance with the exemplary embodiment, the
liquid desiccant takes the form of aqueous alkali halides, aqueous
alkali nitrates, or glycol. Alkali halides include lithium bromide
(LiBr), lithium chloride (LiCl), calcium chloride (CaCl.sub.2),
zinc chloride (ZnCl.sub.2), zinc bromide (ZnBr) and the like.
Alkali nitrates include potassium nitrate (kNO.sub.3), and lithium
nitrate (LiNO.sub.3), and the like. Glycol includes ethylene glycol
(C.sub.2H.sub.6O.sub.2) and the like. Of course it should be
understood that the particular type of liquid desiccant could
readily vary.
[0013] First circuit portion 46 leads from intercooler 44 to a
flash drum 55. Coolant or water laden liquid desiccant enters an
inlet 57 of flash drum 55. In flash drum 55, the water from the
water laden liquid desiccant flashes or vaporizes leaving behind a
concentrated solution or substantially water free liquid desiccant.
By substantially water free, it should be understood that the
liquid desiccant leaving flash drum 55 has a water content that is
at least 0.4% less than the water content of the liquid desiccant
entering flash drum 55. The vapor passes from flash drum 55 through
a vapor outlet 60 and the substantially water free liquid desiccant
passes from flash drum 55 through a liquid desiccant outlet 63.
[0014] The substantially water free laden liquid desiccant passed
from liquid desiccant outlet 63 to a heat exchanger 68. Heat
exchanger 68 removes heat entrained within the substantially water
free liquid desiccant. From heat exchanger 68, the substantially
water free liquid desiccant is directed through a liquid desiccant
spray member 71 by a pump 74. Liquid desiccant spray member 71
distributes the substantially water free liquid desiccant into wet
or humid air flowing upward from cooling tower 50. The
substantially water free liquid desiccant absorbs moisture
entrained in the wet or humid air, transforms into water laden
liquid desiccant, and falls into a liquid desiccant collector 80. A
pump 84 urges the water laden liquid desiccant back to first
circuit 46 of intercooler 44.
[0015] In further accordance with the exemplary embodiment, vapor
passing from flash drum 55 is guided to a condenser 100. The vapor
is cooled and transformed into make-up water. The make-up water is
then passed to a water spray member 104 by a pump 106. At this
point it should be understood that additional make-up water may be
supplied to water spray member 104 via an external water supply
conduit 108. The make-up water falls or is sprayed upon a secondary
heat exchanger or cooler 120. Secondary cooler 120 is used to
reject the remaining heat from second circuit portion 48 to
ambient. In accordance with one aspect of the exemplary embodiment,
secondary cooler 120 includes a wicking material that is utilized
to enhance evaporative performance. In accordance with one aspect
of the exemplary embodiment, collection tray 125 is arranged below
secondary cooler 120. The collection tray is positioned to catch
excess water passing from secondary cooler 120. A pump (not shown)
is fluidly connected to collection tray 125 and operates to
recirculate any recovered water back to, for example, pump 106.
Another pump 130 urges cooling water back to second circuit portion
48 of intercooler 44. With this arrangement, water recovery system
40 not only reduces the loss of water exiting a cooling tower, but
also provides cooling to lower temperatures of compressor
extractions. Of course, it should be understood that the
intercooler (or equivalent heat exchanger) coupled to a cooling
tower could be employed in a wide variety of installations such as
a steam turbine condenser system but should not be considered as
being limited to cooling turbomachine extractions.
[0016] The exemplary embodiment has advantages over alternative dry
cooling solutions. A conventional dry cooling system would supply
high temperature coolant exiting the intercooler to an air-cooled
heat exchanger. The coolant would be cooled in the air-cooled heat
exchanger to a required return temperature of the intercooler.
Air-cooled heat exchangers designed for this purpose are very large
and expensive, in order to be suitable for ambient conditions that
include above normal temperatures that often provide small
temperature differences between the air and the coolant return
temperature. In contrast, the exemplary embodiment permits the
air-cooled heat exchanger to be operated at higher exiting
temperatures than is possible with conventional dry cooling system.
For example, exiting temperature of the liquid desiccant air-cooler
is about 122.degree. F. (50.degree. C.). This is significantly
higher than the required intercooler return temperature of about
102.degree. F. (38.9.degree. C.). This added temperature margin or
driving force leads to smaller and less expensive air-coolers and
greater operating margin in hot weather.
[0017] An additional advantage of the exemplary embodiment is
flexibility in operating conditions. For example, it is possible to
operate the cooling system so that liquid desiccant collects nearly
all of the water used in the cooling tower, so that very little
makeup water is required. However the system can be designed to
have the flexibility to use more water in the cooling tower than is
collected by the liquid desiccant. This operation may be useful in
hot weather as it allows the system to be optimized for year-round
performance, as opposed to be designed for the most challenging
conditions.
[0018] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *