U.S. patent application number 13/266586 was filed with the patent office on 2012-03-22 for power plant with co2 capture and water treatment plant.
This patent application is currently assigned to ALSTOM TECHNOLOGY LTD. Invention is credited to Dario Breschi, Olivier Drenik.
Application Number | 20120067046 13/266586 |
Document ID | / |
Family ID | 42136128 |
Filed Date | 2012-03-22 |
United States Patent
Application |
20120067046 |
Kind Code |
A1 |
Drenik; Olivier ; et
al. |
March 22, 2012 |
POWER PLANT WITH CO2 CAPTURE AND WATER TREATMENT PLANT
Abstract
A power plant for the generation of electrical energy comprises
steam and/or gas turbines (2, 3, 4, 13) driven by fossil fuels and
a CO2 capture system (20) for capturing CO2 gases from the flue
gases that result from the combustion of the fossil fuels. It
furthermore comprises a CO2 gas processing unit (GPU) for the
compression and cooling of the captured CO2. A cooling circuit (24)
of the gas processing unit (GPU) forms a closed loop that includes
a heat exchanger (25) for the heating of brine, where this heat
exchanger (25) is part of a water treatment system having a
multi-stage flash distiller (MSF). In the closed loop (24)
low-temperature waste heat from the CO2 gas processing unit (GPU)
is utilized for the water treatment system. The overall power plant
energy efficiency is thereby increased.
Inventors: |
Drenik; Olivier; (Belfort,
FR) ; Breschi; Dario; (Anjoutey, FR) |
Assignee: |
ALSTOM TECHNOLOGY LTD
Baden
CH
|
Family ID: |
42136128 |
Appl. No.: |
13/266586 |
Filed: |
April 21, 2010 |
PCT Filed: |
April 21, 2010 |
PCT NO: |
PCT/EP2010/055239 |
371 Date: |
November 30, 2011 |
Current U.S.
Class: |
60/645 ;
60/670 |
Current CPC
Class: |
B01D 1/26 20130101; C02F
1/048 20130101; F01K 13/00 20130101; F01K 23/10 20130101; B01D
1/0058 20130101; Y02P 20/129 20151101; Y02E 20/326 20130101; Y02E
20/16 20130101; C02F 1/16 20130101; Y02E 20/32 20130101 |
Class at
Publication: |
60/645 ;
60/670 |
International
Class: |
F01K 13/00 20060101
F01K013/00; F01K 21/00 20060101 F01K021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2009 |
EP |
09159259.2 |
Claims
1. A power plant for the generation of electrical energy comprising
one or more steam turbines (2, 3, 4) or one or more gas turbines
(13) or both, which are driven by fossil fuels, the power plant
further comprising a CO.sub.2capture system for capturing CO.sub.2
gases from the flue gases that result from the combustion of the
fossil fuels and a gas processing unit (GPU) for processing the
captured CO.sub.2 having one or more compressors (30) and one or
more coolers (23) for the compression and cooling of the CO.sub.2
gas, the power plant comprising: a water treatment system having a
multi-stage flash distiller (MSF) in fluid communication with a
first heat exchanger (25) for the heating of brine flowing through
the water treatment system, wherein the first heat exchanger (25)
is configured and arranged for a heat exchanging medium to pass
therethrough, wherein the heat exchanging medium results from one
or more coolers (23) adapted for the cooling of the CO.sub.2gas and
wherein the heat exchanging medium is directed back to the one or
more coolers (23) for the cooling of the CO.sub.2 gas after exiting
the first heat exchanger (25).
2. The power plant according to claim 1, further comprising a
second heat exchanger (45), wherein the second heat exchanger (45)
is configured and arranged for preheating raw feedwater prior to
its entry into the MSF distiller and for a heat exchanging medium,
which results from the one or more coolers (23) for the cooling of
the CO.sub.2 gas and from the first heat exchanger (25) of the
multi-stage flash distiller (MSF), wherein this heat exchanging
medium is directed back to the one or more coolers (23) for the
cooling of the CO.sub.2 gas after exiting the first heat exchanger
(25).
3. The power plant according to claim 1, wherein the heat
exchanging medium resulting from the coolers (23) for the cooling
of the CO.sub.2 gas has a temperature less than 90.degree. C. at
its entry into the first heat exchanger (25).
4. The power plant according to claim 1, wherein the multi-stage
flash distiller (MSF) is configured and arranged to separate raw
feedwater to be treated into a distillate flow and a brine
flow.
5. The power plant according to claim 1, wherein the power plant
further comprises a unit for reducing the brine flow to a
solid.
6. The power plant according to claim 5, wherein the unit is a
zero-liquid discharge crystallizer (60).
7. The power plant according to claim 2, wherein the raw feedwater
flow directed to the multi-stage flash distiller (MSF) is waste
water from the power plant, sea water, and/or raw water from an
external source.
8. The power plant according to claim 1, further comprising a
deaereator is provided in a conduit (40, 53, 47) for the raw
feedwater upstream of the multi-stage flash distiller (MSF)
evaporator.
9. The power plant according to claim 1, further comprising a
conduit (28) configured to provide low-pressure steam to the first
heat exchanger (25).
10. The power plant according to claim 2, wherein the heat
exchanging medium flowing through the first heat exchanger (25) or
the first and the second heat exchangers (25, 45) is water, oil, or
vapor.
11. A method of operating the power plant of claim 2, wherein a
ratio of a saline concentration of the brine blowdown exiting from
the multistage distiller (MSF) to a saline concentration of the raw
feedwater entering the multi-stage distiller (MSF) is in the range
from 10 to 100.
12. The method of operating a power plant of claim 2, wherein a
ratio of a saline concentration of the brine blowdown to a saline
concentration of the raw feedwater to be treated is 50.
13. The method of operating a power plant of claim 1, wherein a
temperature of the brine at its entry into a first chamber (31) of
the multi-stage distiller (MSF) after being heating in the first
heat exchanger (25) is in the range from 50 to 70.degree. C., and a
heat source temperature of the heat exchanging medium flowing
through the first heat exchanger (25) or through the first and
second heat exchangers (25, 45) is 70.degree. C. at its entry into
the first heat exchanger (25) and 45.degree. C. at its exit from
the first heat exchanger (25) or second heat exchanger (45), and a
temperature difference between the temperature of the brine
entering the multi-stage distiller (MSF) and the temperature of the
brine leaving the multi-stage 5 distiller (MSF) is in the range
from 25 to 45.degree. C.
14. The method according to claim 13, wherein the temperature of
the brine at its entry into the first chamber (31) of the
multistage distiller (MSF) after being heating in the first heat
exchanger (25) is 60.degree. C., and the heat source temperature of
the heat exchanging medium flowing through the first heat exchanger
(25) or through the first and second heat exchangers (25, 45) is
70.degree. C. at its entry into the first heat exchanger (25) and
45.degree. C. at its exit from 5 the first heat exchanger (25) or
second heat exchanger (45), and the temperature difference between
the temperature of the brine entering the multi-stage distiller
(MSF) and the temperature of the brine leaving the multi-stage
distiller (MSF) is 35.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a power plant for the generation of
electrical energy having a carbon dioxide capture system. It
furthermore pertains to a system for treatment of water.
[0002] It is known that power plants for the generation of
electrical energy having gas and/or steam turbines driven by fossil
fuels may be equipped with systems for the capture of carbon
dioxide from the flue gas resulting from the combustion of the
fossil fuels. Power plants with CO.sub.2 capture systems can
therefore be steam, gas, combined-cycle power plants, where the
steam power plants can have all types of boilers including
oxy-fired fluidized bed boilers. Such CO.sub.2capture systems
include for example systems of absorption or desorption of the
CO.sub.2 from the flue gases and subsequent compression, cooling,
and liquefying of the captured CO.sub.2. The process of cooling of
the CO.sub.2 gases is realized for example by means of heat
exchangers using water as a heat exchanging medium. The resulting
heated water contains heat that generally is considered as waste
heat.
[0003] Various systems for the treatment of industrial waste water,
sea water, or other non-fresh water are known. For example,
filtration-membrane-softening systems are known for the treatment
of a given restricted range of turbidity or chemical composition of
the water that can be treated and with a limited maximum purity
achievable by the filtration. The membrane systems are typically
constructed for the filtration of water of a given range of
contamination and require significant electrical energy as well as
the use of chemicals.
[0004] Industrial facilities frequently use evaporation systems for
their waste water treatment such as vertical tube, falling film
vapor compression type evaporators. They are operated typically
either with electrical power or with steam of a pressure above 2
bars abs. Multistage flash distillers are known for their use in
desalination of sea water.
BRIEF SUMMARY
[0005] The object of the present invention is to provide a power
plant for the generation of electrical energy comprising steam
and/or gas turbines and a CO.sub.2capture and cooling system, where
the power plant has improved energy efficiency over conventional
power plants.
[0006] It is another object of the invention to provide a method of
operating such power plant.
[0007] A power plant for the generation of electrical energy
comprising one or more steam and/or gas turbines driven by fossil
fuels and a CO.sub.2 capture system for capturing or extracting
CO.sub.2 gases from the flue gases resulting from the combustion of
the fossil fuels and furthermore a unit for the processing the
captured CO.sub.2, where this unit includes one or more compressors
and coolers for the compression and cooling of the captured
CO.sub.2 gas. According to the invention, this power plant
comprises a water treatment system having a multi-stage flash
distiller with a first heat exchanger, or brine heater, for heating
brine circulating through the MSF. In particular, this first heat
exchanger is arranged for a heat exchanging medium to pass through
it and thereby heating brine circulating the MSF, where this heat
exchanging medium is the cooling medium exiting from the coolers
for the cooling of the compressed CO.sub.2 gas. This first heat
exchanger or brine heater is furthermore configured and arranged
such that its heat exchanging medium is directed, after its exit
from this first heat exchanger in the multi-stage flash distiller,
back to the coolers for the cooling of the CO.sub.2 gas. Thereby, a
closed loop is formed for the cooling medium for the CO.sub.2
coolers.
[0008] The heat exchanging medium for the cooling of the compressed
CO.sub.2 passes through one or more heat exchangers within the
processing unit for the CO.sub.2. When this heat exchanging medium,
for example water, oil or vapor, exits from the cooling unit, its
heat content is of low-grade and conventionally considered a
low-temperature waste heat. The power plant according to the
invention puts this low temperature waste heat to efficient use in
a water treatment system, specifically for providing the heat
necessary for the operation of a multi-stage flash distiller. The
multi-stage flash distiller separates raw feedwater to be treated
into two flows, a high purity distillate flow and a low-volume,
concentrated brine flow. The distillate may be used, for example,
for industrial purposes or for fresh water drinking following a
re-mineralization. A part of the brine flow can be either directly
disposed to waste or directed to a further unit for reducing it to
a solid, for example a zero-liquid discharge crystallizer. Another
part of the brine flow is recirculated through the MSF evaporator,
where it acts as a cooling medium for the vapor generated by the
flashing brine in the MSF flash chambers. The raw feedwater is
introduced into the MSF at a stage of the MSF suitable in view of
efficient heat recovery.
[0009] Power plants with CO.sub.2 capture systems typically produce
saline water flows generated as process waste by the condensation
of flue gas from the boilers. Additionally, such power plants also
have a by-product in the form of large amounts of low-temperature
heat conveyed by a liquid medium having a temperature typically
less than 90.degree. C., resulting from the CO.sub.2 capture
equipment such as CO.sub.2 coolers or flue gas coolers. Due to its
low temperature, this low-temperature heat is generally not
utilizable for power generation. However, in the power plant
according to this invention, low-temperature heat from the CO.sub.2
cooling is recovered in a closed-loop system and exploited as a
heat source for the treatment of waste water that is a by-product
of same power plant. This waste water can be flue gas condensate or
any other industrial waste of same power plant or also any raw
water from any external source. As such, the power plant according
to the invention has an increased overall energy efficiency over
conventional plants.
[0010] The power plant with integrated system for a water treatment
by distillation according to the invention yields several
advantages. The power plant recovers energy otherwise wasted and
instead uses it for water purification thereby reducing the energy
cost of the water treatment system. The multi stage flash distiller
facilitates a high concentration level of the resulting brine, i.e.
the concentrated wastewater. This allows in turn further treatment
of the brine by means of a crystallizer reducing the brine to solid
form, which is disposed of more easily than waste liquid form.
Furthermore, the power plant in combination with the water
treatment by distillation allows the treatment of water of a
greater range of turbidity, salinity, pH values, and contaminants
such as organic carbons, for example in comparison to water
treatment based on membrane systems.
[0011] Furthermore, the purity of the resulting distillate is
higher than that achievable by a conventional membrane system.
[0012] The power plant with a water treatment system according to
the invention furthermore is environmentally more compatible in
several aspects over conventional water treatment systems. It
requires no fresh water intake from the natural environment such as
from a river or lake. Compared to conventional water treatment
systems it requires a highly reduced consumption of chemicals. The
high concentration of the resulting brine and further reduction of
the brine to a solid eliminates a disposal or storage of liquid
waste. Due to the efficient utilization of the waste heat of the
power plant, the final waste heat is released to ambient at reduced
temperature.
[0013] In an embodiment of the invention, the power plant with
CO.sub.2 capture system and water treatment system comprises
additionally, a second heat exchanger, or feedwater preheater for
preheating the waste water to be treated prior to its entry into
the multi-stage flash distiller. This second heat exchanger is
configured and arranged for a heat exchanging medium that passes
through it in counterflow to the raw water or feedwater, which is
to be preheated, where the heat exchanging medium results from the
CO.sub.2 cooling process of the CO.sub.2 capture system and has
passed through the first heat exchanger or brine heater of the
multi-stage flash distiller. After the preheater, the heat
exchanging medium is directed back to the CO.sub.2 cooling unit of
the CO.sub.2 capture system. Thereby the closed loop of the cooling
medium for the CO.sub.2 cooler is again formed. The heat exchanging
medium flowing through the second heat exchanger is water or
another heat exchanging medium that
[0014] The second heat exchanger, or preheater for the raw
feedwater to the multi-stage flash distiller, allows the recovery
of heat from the closed loop of the CO.sub.2 compressor cooling.
Moreover, it provides the capability to extend the temperature
range of effective waste heat recovery from the CO.sub.2 capture
system down to a value of 45.degree..
[0015] The multi-stage flash distiller, here also referred to as
MSF distiller or MSF, integrated with a power plant with CO.sub.2
capture facility allows the treatment and purification of water
having a greater range of contamination or chemical composition
compared to other types of raw water typically treated in an MSF,
for example seawater. In the configuration according to the
invention and in order to handle this larger range of
contamination, the MSF is operated using a set of specifically
chosen operating parameters.
[0016] In a method of operating the power plant according to the
invention, the MSF distiller is operated with operating parameters
in the following value ranges. For comparison, the values of
operating parameters of conventionally known and operated
multi-stage flash distillers are given in parentheses.
[0017] Top brine temperature, which is the temperature of the brine
at its entry into the first chamber of the MSF after being heating
in the first heat exchanger or brine heater: according to the
present invention: 50-70.degree. C., most suitably 60.degree. C.
(conventional: 90-120.degree. C.).
[0018] Heat source temperature, which is the temperature of the
heat source or exchanging medium, preferably water, flowing through
the first heat exchanger or through first and second heat
exchangers and back to the CO.sub.2 coolers. The temperatures given
are the temperature of the heat source at the entry into the first
heat exchanger and the temperature at its exit from the heat
exchanger or heat exchangers: according to the present invention:
70.degree. C., 45.degree. C., (conventional: 130.degree. C.,
100.degree. C.);
[0019] The flash range, which is the temperature difference between
the temperature of the brine entering the MSF and the temperature
of the brine leaving the MSF: according to the present invention:
25-45.degree. C., most suitably 35.degree. (conventional:
60-80.degree. C.);
[0020] The concentration ratio, which is the ratio of the saline
concentration of the brine blowdown exiting from the multi-stage
distiller to the saline concentration of the raw feedwater to be
treated entering the multi-stage distiller: according to the
present invention: 10-100, for example 50, (conventional 1
0.5-2).
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows schematically a power plant according to the
invention comprising a CO.sub.2 capture system and a water
treatment system with a multistage flash distiller.
[0022] FIG. 2a shows schematically and in greater detail a first
embodiment of a water treatment system suitable for integration in
a power plant of FIG. 1.
[0023] FIG. 2b shows schematically and in greater detail a second
embodiment of a water treatment system suitable for integration in
a power plant of FIG. 1.
[0024] FIG. 3 shows schematically a water treatment system suitable
for the integration within a power plant of FIG. 1.
[0025] Same numbers for elements of the power plant in different
figures indicate the same elements.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The power plant according to the invention can be any fossil
fuel powered plant including a purely steam turbine driven or
purely gas turbine driven power plant or a combined cycle power
plant comprising both steam and gas turbines. FIG. 1 shows a
diagram of a combined cycle power plant as an example power plant
according to the invention. The power plant for the generation of
electrical energy comprises a boiler 1, and high pressure,
intermediate, and low pressure steam turbines 2, 3, and 4
respectively driving a generator 5. Following expansion in the
turbines the steam is condensed in a condenser 6. The resulting
condensate and feed water is degassed and preheated in apparatuses
7 and 8 and directed back to the boiler 1, thereby completing the
water-steam-cycle. The power plant further comprises a compressor
11, combustor 12, and gas turbine 13 driving a further generator
14. The flue gases from the gas turbine are directed into the
boiler 1, for example a heat recovery steam generator, where the
flue gas heat is used for steam generation. In the case of a purely
steam turbine driven power plant, the boiler can also be a coal
fired boiler or other fossil fuel fired boilers.
[0027] The flue gases exiting from the boiler 1 as shown, or from a
coal fired boiler, oxyfired fluidized bed boiler, or any other
fossil fueled boiler, are directed for suitable treatment to a flue
gas treatment facility 22 and then to a CO.sub.2 capture facility
20, for example absorption or thermophysical separation. CO.sub.2
gas extracted by this facility is led via a line 21 to a GPU. In
the GPU, the CO.sub.2 gas is compressed in several stages with
inter-coolers or heat exchangers 23 in order to reduce the volume
of the CO.sub.2 and hence the electrical consumption of the
compressors. The power plant is integrated with a water treatment
system in that the heat exchange medium of the gas processing unit
GPU is directed in a closed loop cooling system 24 through the gas
cooling system 23, GPU and through a shell and tube heat exchanger
25 arranged within a multi stage flash distiller MSF of the water
treatment system. Having gained a low-temperature heat from cooling
the CO.sub.2 gas, it releases this low-temperature heat in the
first heat exchanger 25 of the MSF in a counterflow to brine
circulating through the MSF. After exiting the heat exchanger 25,
it is returned to the heat exchangers 23 of the gas processing unit
GPU. This heat exchange medium is most suitably water.
[0028] The water from the gas processing unit GPU is heated by heat
exchange with the compressed CO.sub.2 to a temperature of less than
90.degree. C. This water is directed via line 26 to the first heat
exchanger or brine heater 25 in the MSF for the heating of brine.
The brine is heated in the heat exchanger 25 prior to entering the
MSF evaporator. The cooling water of the closed loop of the
CO.sub.2 cooler medium is cooled down at the same time by passing
through the heat exchanger 25.
[0029] FIG. 2a shows in detail the part of the power plant
according to the invention concerned with the compression and
cooling of the CO.sub.2 gas and the integration of the power plant
for the generation of electrical energy with the water treatment
plant. The plant comprises a compression facility 22 with several
compressors 30, the lines for the compressed CO.sub.2 gas leading
from each compressor 30 to one of several heat exchangers or
intercoolers 23 of the gas processing unit GPU. The first heat
exchanger 25 or brine heater of the MSF is connected on the side of
the heating medium flowing through its shell to the heat exchangers
23 of the GPU via lines 26 and 27. On the side of the brine flowing
through the heat exchanger tubes, the heat exchanger 25 is part of
the main circuit of the MSF evaporator. It effectively uses the
low-temperature heat from the cooling unit GPU for the heating of
the brine to be distilled. The MSF further comprises a heat
recovery section HRS having several chambers or stages 31 of flash
distillers arranged in series, where the brine flashes at the
bottom of each stage 31 and 31' of the MSF evaporator. The
evaporator includes a heat recovery section HRS and a heat reject
section 37. The brine heated in heat exchanger or brine heater 25
is led into the first flash chamber 31, where the pressure is kept
by thermodynamic equilibrium at a value to allow flashing of the
incoming brine, such that it partially vaporizes. The vapor rising
to the top of each flash chamber 31, condenses on exchanger tubes
32 in the form of distillate. The process of flashing, partial
evaporation, and condensation repeats at decreasing temperatures
and pressures in all the stages 31 of the heat recovery section HRS
and stages 31' of the heat reject section 37. The distillate of
each stage is collected in pans and led via a line 33 to a
distillate tank 34. At the bottom of the flash distiller stage
chambers 31, the non-evaporated contaminants of the brine are
collected and led via line 35 to further treatment.
[0030] The MSF comprises the heat reject system 37 containing
further flash evaporation chambers 31' and condensing tubes for
condensing the vapor. These condensing tubes have a cooling medium
flowing through them that is circulated in a closed loop through an
air cooler 38 having air inlet and air outlet lines 38' and 38''.
Most of the flashed brine, is extracted from the very last flash
chamber 31' of the heat reject system 37 by means of a brine
recirculation pump and led to the MSF via line 39 to the condensing
tubes 32 of the flash chambers 31 of the heat recovery section HRS.
There the brine acts as a cooling medium for the vapor generated in
the flash chambers 31. A part of the brine is extracted from the
last chamber of the MSF by a separate pump and discharged via line
35 as blowdown in order to keep a constant concentration of the
recirculating brine, which is recirculated via line 39 to the heat
recovery section HRS of the MSF. Non-condensable gases are
extracted from the heat reject system 37 via a vacuum system
41.
[0031] Feedwater is introduced via a line 40 at a suitable stage of
the MSF evaporator depending on the temperature of the feedwater.
In the shown embodiment, the feedwater line is introduced into the
heat reject section 37 of the MSF. A deaereator could be provided
upstream of the MSF evaporator in order to separate the air
dissolved in the feed water.
[0032] A low-pressure steam line 28 leads into the first heat
exchanger 25 in order to allow the introduction of low-pressure
steam into the heat exchanger at times of start-up of the system
and/or during transient conditions.
[0033] A further embodiment of the invention regarding the
introduction of feed water into the water treatment system is shown
in FIG. 2b. The system is based on the same principles as that of
FIG. 2a. In comparison to the system of FIG. 2a, it comprises
additionally a second heat exchanger 45 for the preheating of the
feedwater to be treated. The preheater 45 is a shell and tube heat
exchanger having on its shell side water or another heat exchanging
medium flowing through its shell that is delivered from the heat
exchanger 25 via line 46. After having passed through the second
heat exchanger 45, the heat exchanging medium, preferably water, is
directed by line 27 back to the coolers 23 of the gas processing
unit GPU. Thereby the loop 24 is closed. On its tube side the heat
exchanger 45 has feed water delivered by line 47 led through it for
preheating. The second heat exchanger or feedwater preheater 45
facilitates a further recovery of remaining heat available in the
cooling medium of the CO.sub.2 gas cooling system and thus allows
further optimization of the energy efficiency of the power
plant.
[0034] A line 48 directs the feed water after its preheating to a
suitable stage 31 of the MSF evaporator.
[0035] FIG. 3 illustrates schematically a full scheme of possible
sources of raw feed water to be treated by the water treatment
system integrated in a power plant according to the invention. Any
combination of the shown sources as well as further similar sources
are possible. The sources presented in FIG. 3 include the boiler
blowdown that is delivered by a line 50 to the MSF and the flue gas
condensate delivered from the CO.sub.2 capture facility 20 via a
line 51 to a raw water tank 52, from where a line leads to a feed
water line 40 or 47. The figure shows the MSF distiller that
receives raw feedwater from two sources, one from the boiler
blowdown BB via line 50 and the other from line 53 delivering raw
water from a raw water tank 52, which has the purpose of levelizing
the feed water delivery to the distillation. The raw water tank 52
can be filled via one or more of the following sources: water from
a neutralization tank NT containing industrial waste water; water
from an external source EXT such as a pond, lake or other similar
source. This water may be pretreated in a facility 58 in order to
remove by sedimentation most of the suspended matter or modify its
pH value according to the actual characteristics; flue gas
condensate FGC may be pretreated in a treatment facility 59 in
order to oxidize CaSO.sub.3 to CaSO.sub.4 having higher solubility.
In the embodiments of both FIGS. 2a and 2b, the MSF is connected to
an air cooler 38 having air inlet line 38' and air outlet line 38''
for the cooling of the cooling medium in the condensing tubes of
the heat reject system 37. A line 33 to a distillate tank 34
directs the distilled water generated by the MSF. Further
distillate collected in the vacuum system 41 may also be delivered
via line 55 to this tank 34.
[0036] The brine from the MSF or brine blowdown is delivered by
line 35 to a zero liquid discharge crystallizer 60, where it is
processed to be reduced to solid crystalline form. These solids are
then to be disposed of as waste. The zero liquid discharge
crystallizer 60 may comprise a crystallizer, a heat recovery heater
for the incoming brine and a mechanical vapor compressor. Any
distilled liquid discharge arising from the solidification process
may also be collected in the distillate tank 34.
[0037] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to make and use the invention. The patentable
scope of the invention is defined by the claims, and may include
other examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims if they
have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural
elements with insubstantial differences from the literal languages
of the claims.
* * * * *