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J E u r o p aEuropean
i s c h e Patent
s
Office
Office europeen des brevets
(11)
EP
0 604
718
B1
E U R O P E A N PATENT S P E C I F I C A T I O N
(12)
(45) Date of publication and mention
of the grant of the patent:
10.09.1997 Bulletin 1997/37
(51) int. CI.6: C01 D 3/06,
B0-| q ■)/28
C01D3/08,
B01 D 1 / 2 6
(21) Application number: 93116320.8
(22) Date of filing: 08.10.1993
(54) Evaporative salt plant
Verdampfungsinstallation zur Salzproduktion
Installation d'evaporation pour la production de sel
(56) References cited:
FR-A- 2 334 825
US-A- 2 660 236
(84) Designated Contracting States:
CH DE FR GB IT LI NL
(30) Priority: 30.12.1992 US 998927
US-A- 2 588 099
• FIFTH INTERNATIONAL SYMPOSIUM ON SALT,
NORTHEN OHIO GEOLOGICAL SOCIETY pages
335 - 339 A. PAVLIK, G. ARCANGELI, J. C.
GALLOT 'Description and operation of a high
capacity evaporator for the production of a very
pure chemical grade salt'
• DATABASE WPI Section PQ, Week 8804,
Derwent Publications Ltd., London, GB; Class
Q52, AN 88-027638 & SU-A-1 317 174 (AIR GAS
TURBO COOL) 15 June 1987
• PATENT ABSTRACTS OF JAPAN vol. 016, no.
157 (M-1236) 16 April 1992 & JP-A-04 008 828
(MITSUI ENG & SHIPBUILD CO LTD) 13 January
1992
(43) Date of publication of application:
06.07.1994 Bulletin 1994/27
(73) Proprietor: Texas Brine Corporation
Houston Texas 77056 (US)
(72) Inventors:
• Becnel, Lawrence R, Jr.
Sugarland, Texas 77479 (US)
• Currey, John E.
Fair Oaks Ranch, Texas 78006 (US)
• Ver Hoeve, Raymond W.
Houston, Texas 77027 (US)
(74) Representative: Weisert, Annekate, Dipl.-lng. Dr.Ing. et al
Patentanwalte
Kraus Weisert & Partner
Thomas-Wimmer-Ring 15
80539 Munchen (DE)
CO
CO
o
CO
o
Q_
LU
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
99(1) European Patent Convention).
Printed by Rank Xerox (UK)Business Services
2.14.12/3.4
EP 0 604 718 B1
Description
BACKGROUND OF THE INVENTION
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Salt is one of the most abundant materials on earth and is one of the largest volume inorganic materials used in
industry in the production of chlorine and caustic soda by the electrolytic processes and is used in the manufacture of
many products, both organic and inorgnic. Salt is also used for snow and ice control and as a mineral in animal diets,
as a food preserative and for flavoring food. Salt is the most common and readily available non-metallic mineral in the
world. Oceans contain an inexaustible supply of salt. The identified resources of salt in the United States alone are estimated at over sixty trillion tons.
Salt is produced by direct removal as rock salt from underground deposits, by solution mining underground deposits, or by evaporation from solution mining or naturally occuring brines or sea water. Underground deposits are large
beds of concentrated salt which have been deposited through evaporation of brines over the geological ages. Underground deposits are mined as rock salt using conventional mining techniques or by solution mining creating a brine. In
solution mining water is pumped into the salt bed, the salt is dissolved in the water and the resultant brine is brought to
the surface. Many processes and techniques have been disclosed for the mining and production of salt from these various raw material sources, and many processes and techniquies have been disclosed for the purification of the salt produced by the mining processes. United States Patents 3,647,396 and 3,655,333 are examples of disclosures of
processes for purifying salt already produced.
Processes have been employed and described in the prior art, e.g. in US-A-2 660 236, US-A-2 588 099, for the production of high purity salt at the initial site where the salt recovery processes are used for the mining of the salt.
Because of the high cost of energy, especially in the cost of petroleum derived energy, created by the changes in the
mid-east two decades ago, which created the energy crisis, many attempts have been made to optimize the conservation of energy in the production of high quality salt. Background information on the processes, equipment and techniques employed in these endevours are described in the Encyclopedia of Chemical Technology, edited by Kirk-Othmer,
Third Edition, Volume 9, under the heading Energy Management starting on page 21 through 45, and under the heading Evaporation, starting on page 472 through 493. Additional background information is also disclosed in the Encyclopedia of Chemical Processing and Design, edited by John J. McKetta, Volume 20, under the heading Evaporator
Operation starting on page 396 continuing under the heading Evaporation through page 445. Perry's Chemical Engineers' Handbook, Sixth Edition, under Evaporators, starting on page 11-31 through 11-43 also provides background
information related to this invention.
A recent process design for the production of evaporative salt from solution mined brine which pursues the objectives of making salt while at the same time conserving the use of energy is described in the publication of the Fifth International Symposium on Salt - Northern Ohio Geological Society in an article by A. Pavik, G. Arcangeli and J.C. Gallot,
starting on page 335 thru 339. The article describes a process installed by Montedison at Ciro Marina-Calbria, Italy. The
article describes a salt plant with solution mining and an evaporation plant employing quadruple effect evaporators and
a mechanical recompression evaporator and includes the generation of steam at high pressure which is used to drive
two steam turbines. One of these steam turbines is connected to an alternator which generates the necessary electric
current used in the plant and the other is used to drive a compressor which recompresses the vapors from the single
effect evaporator, so that it can be reused in the heating elements of the single effect evaporator. The excess steam
from both steam turbines is used to drive the quadruple effect evaporator train.
In accordance with this invention, we employ a methods and plant installation which produce high purity salt economically and in high yield, comprising the combination of a gas turbine which drives a vapor compressor while the gas
turbine exhaust gases are used to produce high pressure steam which is used to drive a steam turbine, which in turn
generates the electrical energy requirements of the plant, and wherein the discharge vapors from the steam turbine are
combined with the discharge vapors from the vapor compressor, which is in turn in combination with a vapor compression evaporator and a purge evaporator, whereby both evaporators produce salt, and where the overhead vapors of the
purge evaporator are used in a brine cooled condenser to preheat input cold brine. Water condensate is recovered from
the evaporator heater and brine cooled condenser and used in solution mining the underground salt, thereby allowing
for productive use and recovery of substantially all the raw material and over 70% of energy inputs to the plant, and
friendly environmental operation of the plant.
The use of a gas turbine and a steam turbine in the same plant installation is per se known by the SU-A-1 31 7 174.
OBJECTS OF THE INVENTION
It is an object of this invention to provide an evaporative salt plant design, including methods, apparatus and systems for operating the plant, to produce high quality salt, in high yield and with considerable savings in both initial capital
investment and operating costs especially in the energy required per ton of salt produced.
It is a further object of this invention to provide an evaporative salt plant design which produces salt of at least
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99.99% and up to 99.9974% purity, with increases in yield or capacity of up to 50%, and with savings in operating cost
of up to 75% of the energy cost to produce a ton of high purity salt, as compared to existing vapor recompression evaporation technology. A 40% and 50% savings in energy use per ton of product is obtained from the single and two stage
evaporation plants described later in connection with Figures I and II, respectively, when compared to the Montedison
plant design described in the Northern Ohio Geological publication referred to above.
It is still a further object of this invention to produced salt by this invention which is suitable for use without further
purification in chlor-alkali electrolytic cells for making chlorine and caustic soda of the diaphgram or mercury cell type,
and with minimal ion exchange treatment for use in membrane type cells, and for direct use in the production of sodium
in molten salt electrolytic cells, and also for many other uses without further purification, including commercial food
grade applications.
It is also an object of this invention to provide methods for operating the unique evaporative salt plant design involving the combination of gas turbine, steam turbine, vapor recompression and purge evaporators, in combination with a
brine cooled condenser, at or near the site where the salt is solution mined in a way which allows for the recovery and
productive use in the plant of substantially all of the raw material and a large percentage of energy inputs to the plant.
It is a still further object of this invention to provide an evaporative salt plant design and methods of operation which
allow for the disposal of waste by-product solutions in disposal wells at the plant site and which also allows for the recovery of the water condensate produced in the plant for use in the solution mining of the underground salt thereby providing an environmentally friendly operation which contributes to maintaining the ecological balance in both the energy and
the materials employed in the operation of the plant.
The use of steam turbines or electric motors to drive vapor recompression evaporators in the production of salt from
brine has been employed and decribed in the prior art processes, for example as disclosed in the Pavlik article referred
to above. However, the employment of steam turbines does not allow for the maximumizing the conservation of energy
or savings in costs per ton of salt produced, or the production of the highest purity salt with the highest yield, as compared with the employment of the unique combination of elements in accordance with this invention.
Gas turbines of the combustion type are described in the McKetta Encyclopedia referred to above in Volume 24,
pages 215 - 280, with pages 267 - 280 being devoted to the use of gas turbines in cogeneration, i.e. the generation of
both heat and power.
BRIEF DESCRIPTION OF THE INVENTION
These and other objects are accomplished by applicant's invention comprising an evaporative salt plant design
including methods, apparatus and systems employing a unique combination of a combustion type gas turbine, where
the heat energy from the gas turbine exhaust generates high pressure steam while, at the same time, the gas turbine
shaft energy drives a vapor compressor, which is in further combination with a combination of a vapor compression
evaporator and a purge evaporator, which evaporators produce the high yield and high purity salt, in combination with
a brine cooled condenser which partially preheats the raw material brine input to the plant and allows for the recovery
of the condensate produced in the plant for use in the solution mining of salt.
The objects of this invention are also realized by applicants invention which further comprises employing in combination, a gas turbine which drives a vapor recompressor, with the gas turbine exhaust heat being recovered in a heat
recovery steam generator (HRSG), where high pressure steam is generated and utilized to power a steam turbine,
which in turn generates the electrical energy requirements of the plant and whose discharge vapors are used in combination with the discharge vapors of the vapor compressor to effect boiling in a salt producing evaporator, which produces excess water vapor overheads above which the vapor compressor has sufficient capacity to handle, which
excess vapors are first used in a purge evaporator to produce additional salt and where the water vapor overheads of
the purge evaporator are used in combination with a brine cooled condenser, to partially preheat the input brine to the
system, thereby producing water condensate which is combined with evaporator heater condensate and together used
in the solution mining of the underground salt.
In order that this invention may be more readily understood it will be described with respect to simplified flow diagrams and to certain preferred embodiments, especially as contained in the attached Figures, and examples given
below; however it is to be understood that these embodiments are not to be construed as limiting the invention except
as defined in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
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Figure I is a flow sheet of a preferred embodiment of the unique evaporative salt plant design which provides the
high purity salt in high yield with considerable energy savings.
Figure II is a flow sheet of another preferred embodiment of this invention showing a gas turbine two stage vapor
recompression evaporator unit which offers still further capacity advantages and energy cost savings per ton of high
quality salt produced.
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DETAILED DESCRIPTION OF THE INVENTION
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We have found an evaporative salt plant design including methods, apparatus and systems comprising a combustion type gas turbine, such as Solar Mars or Centaur Taurus gas turbines (Solar Corporation, San Diego, CA), the
exhaust gases of which are employed to raise steam to drive a steam turbine which in turn generates the electrical
energy requirements of the plant, while the discharge vapors from the steam turbine are used in combination with the
discharge vapors from a centrifugal vapor compressor to evaporate brine thereby producing salt and water condensate,
in a combination of a vapor recompression evaporator with a purge evaporator, the overhead vapors of the purge evaporator being used for partial preheating the plants input brine requirements, in a brine cooled condenser, which allows
for the recovery of the balance of water condensate and its subsequent use in solution mining of the underground salt.
Thus in accordance with our invention, there is both productive and conservation use and recovery of the raw materials
and energy inputs to the plant, providing high yields of high purity salt production, while at the same time maintaining
ecological balances in both the energy balance and the materials balance employed in the operation of the plant,
thereby producing a friendly environmental operation of the plant.
Among the features of this invention which are shown in the Figures are the following:
A heat recovery steam generator (HRSG), such as ERI tubular waste heat boiler, (Nebrasaka Boiler, Inc. Lincoln,
NE) to recover gas turbine exhaust heat by generation of high pressure steam which, after being expanded in a steam
turbine driving a generator, is used to apply additional heat input to the vapor compression evaporator steam chest,
which produces additional salt slurry and an excess of water vapor overheads.
Also, by routing this excess water vapor to a purge evaporator, which is operated at near atmospheric pressure in
accordance with our invention, further boiling is induced to produce more salt from feed streams routed to it as more
fully described in connection with the Figures.
Still further, by employing vapors from the purge evaporator in the initial stage of preheating the feed brine, either
before or after it is employed in washing the salt slurry from the elutriating legs of both the vapor compression evaporator and the purge evaporator, a brine temperature of in excess of 60°C (1 40 degrees Farenheit) is produced as the brine
is used to condense all vapors from the purge evaporator, thereby not only allowing completion of recovery of about
95% of the water required for the solution mining of the underground salt, but also for further use of the heat energy so
produced.
In addition, by employing the combination of a vapor compression evaporator and a purge evaporator, in accordance with our design and operations, instead of employing the quadruple effect or other multiple effect evaporators in
the production of salt as described in the prior art, we achieve superior energy economy, and avoid the necessity of vacuum operation of the evaporators we employ, while at the same time being able to produce high purity salt of less than
25 ppm sulfate ion and less than 2 ppm total metals, including calcium, magnesium, strontium and other undesirables,
thereby allowing for production of NaCI having 99.9974+% purity.
Furthermore, when employing the unique combination of elements as disclosed herein at the site of the solution
mining of the brine, the disposal of by-product waste solutions may not only be returned to the earth, where they originally came from, in disposal wells, thereby aiding in preserving the ecological balance, but in addition by utilizing a brine
disposal well one may employ a satisfactory purge for controlling the amount of sulfate in the vapor compression and
purge evaporators thereby allowing for the production of very pure salt crystalls.
A significant advantage is realized by employing a two stage vapor recompressor in combination with two vapor
recompression evaporators in series as shown in Figure II. This combination alone provides for an 8 to 10% increase
in production capacity and concomitant energy and manufacturing cost reductions. Then, upon adding the purge evaporator, an additional 10% capacity boost is acheived at no added energy cost. Thus the combination shown in Figure II
has a capacity of about 3,048,000 kg (3000 tons) per day versus about 2540000 kg (2500 tons) per day for the process
in Figure I, and the two stage system of Figure II operates with essentially the same total fuel input to the process as is
used in the system of Figure I, because the same molel gas turbine is employed.
The basic distinction between employing Figure I and Figre II processes is in the compressor design. A single
wheel, 1.8:1 compression ratio centrifugal machine is employed for driving the single VRC evaporator whereas a two
stage (two wheels or more), 3.2;1 compression ratio machine is employed for driving the two VRC evaporators in series.
In both cases discussed herein, the same model gas turbine is employed. However, many gas turbine/compressor combinations may be employed.
In addition, best results in economy and performance are realized when the combinations of this invention are
arranged and operated in accordance with the disclosures made herein.
Referring to the drawings which were briefly described above; specifically Figure I which is a flow sheet of a preferred embodiment of our invention depicting an evaporative salt plant design for the production of substantially pure
salt, having a purity of at least 99.9974% NaCI purity.
The following description of Figure I first describes the routing of streams containing salt (brine streams), then
describes routing of steam condensate streams, and finally the routing of steam streams, which supply all of the energy
for the process.
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In Figure I, the brine production facility (1) includes a solution mining brine installation for producing treated and polished brine having loss than 10 ppm calcium, magnesium, and strontium ions and less than 500 ppm sulfate ion, and
saturated in salt. This brine (2) is transported by pipeline to the salt plant site, arriving there at about 23.9°C (75 degrees
F), where it is fed to a brine cooled condenser (3) (BCC), a shell and tube heat exchanger, for an initial stage of preheating effected by condensing the hot overhead vapors (4), which are at about 100.6°C (213 degrees F) after desuperheating. These vapors (4) are discharging from the purge evaporator (5), which is operated at about atmospheric
pressure and about 109.1°C (228 degrees F). The elevated temperature is the result of boiling point elevation due to
the concentration of salt in the boiling solution. The sources of brine feed and energy for the purge evaporator (5) are
described later.
A portion of the brine (6) exiting the brine cooled condenser (BCC) (3), at about 60°C (140 degrees F), is diverted
to the purge evaporator (5) elutriating leg via line (7). Another portion is diverted to the vapor recompressor (VRC) evaporator (12) elutriating leg via line (8). The balance (9) and majority (about 75%) of the brine is fed to the brine preheater
(BP) (10), a plate and frame heat exchanger, for final preheating to the operating temperature (about 126.1°C (259
degrees F)) of the VRC evaporator (12). Line (1 1) transfers preheated brine into the VRC evaporator (12). Final preheating is effected by transfer of heat from hot condensate exiting the VRC evaporator (12) circulating heater (CH1).
As one follows the brine and salt streams through the system from this point:
1- Evaporated salt is removed as slurry (13) from the VRC evaporator (12) through its elutriating leg in which it is
washed and cooled to about 65.6°C (150 degrees F) by brine (8) entering the bottom of the leg.
2- Impurities dissolved in VRC evaporator contents are controlled by purging brine liquor (1 4) at about 259 degrees
F from the VRC evaporator (12) to the purge evaporator (5, where additional evaporation will be effected as discussed later.
3- Feed liquor (1 4) and elutriating brine (7) make up the feeds to the purge evaporator (5). Salt slurry (1 5) produced
in that evaporator (5) is washed and cooled to about 126.1°C (150 degrees F) by brine (7) entering the bottom of
the purge evaporator elutriating leg. This slurry stream (15) and salt slurry stream (13) are both sent to the salt
processing facility (1 7) where the slurries are centrifuged and prepared for shipment.
4- Impurities dissolved in the contents of the purge evaporator (5) are controlled by purging brine liquor (16), at
about 109.1°C (228 degrees F), which is sent to a disposal well facility (18), which includes a dilution station, air
cooler, tank, pumps and a disposal well. Sulfate ion content of the liquor (1 6) is controlled to produce the high purity
salt by varing the purge rate.
Now we will refer to the conensate streams which originate at the brine cooled condenser (19), at both the purge
and VRC evaporator circuiting heaters (CH1 and CH2) (20 and 21), from the heat recovery steam generator (27)
(HRSG), and from the vapor wash tank (not shown). The vapor wash tank is used to wash VRC evaporator overhead
steam (25) of entrainment prior to introduction into the vapor compressor (26) suction nozzle. These streams, (19, 20
and 21), with the exception of vapor wash tank condensate, are collected in a condensate storage tank (23) and
returned to the brine production facility (1) in pipeline (24). There it is used with makeup water to solution mine the salt
deposit. Before it is routed to the condensate storage tank (23), stream (21) passes through the brine preheater (10)
where its' sensible heat is released to the feed brine stream (9) prior to transferring it via line (22) to the condensate
storage. In this configuration, recovery of sensible heat from this large condensate stream (21) is economically feasible.
Such recovery of sensible heat from streams (1 9) and (20) is possible but not economical in this particular arrangement
of the process. However, streams (19) and (20) are employable for heating buildings, shops, warehouses, etc. to avoid
loss of this low grade energy.
Vapor wash tank (VWT) condensate, which is a minor salt carrier, is utilized to dilute (desaturate) stream (16),
which is the purge from the purge evaporator, thereby avoiding salt precipitation and plugging of cooler heat exchange
surfaces.
An internal loop exists within the condensate system in which condensate from storage (23) is fed via line (28) to
supply feed water to the HRSG (27) and desuperheating condensate to each evaporator overhead stream, and also to
the VRC compressor discharge (26) via line (29). Desuperheating avoids poor heat transfer efficiency in the large circulting heaters (CH1 and CH2) and brine cooled condenser (3) and cools the suction stream of the VRC compressor
(26) to maximize compressor efficiency.
To provide for desuperheating steam vapor, line (29) branches in at least four locations, including the vapor recompressor discharge (30), vapor wash tank (not shown), VRC evaporator (12) overhead vapor to the purge evaporator circulating heater (31), and purge evaporator (5) overhead vapors (4) to the brine cooled condenser (3). Other uses (not
shown) for the condensate include line washing for deposit removal and demister washing.
The only source of energy input for this process is fuel burned in a combustion gas turbine (37) which supplies
energy to the process by two means. The first is combustion gas turbine (CGT) (37) shaft mechanical energy which
drives the vapor recompressor (26). This compressor draws steam from the VRC evaporator (12) at about 1.7 Bar (1 0
psig) and increasess its pressure to about 3.1 Bar (30 psig) which allows economical heating of the evaporator circu-
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lating heater (CH1). The second means is recovery of gas turbine (37) exhaust gas energy (34) by producing 42.4 Bar,
437.8°C (600 psig, 820 degree F) steam (32) with a (HRGS) (27). This recovered energy is employed to drive a back
pressure (topping) steam turbine generator (35) for supplying electrical power used in the plant. Exhaust steam (33)
from the steam turbine (35) is combined with VRC discharge vapors in line (30), desuperheated, and fed via line (36)
to the VRC evaporator (12) circulating heater (CH1) where it is condensed.
The above paragraph describes the essence of energy transfer to the process VRC evaporator (1 2). Steam generated in the HRSG (27) and vaporized desuperheating condensate fed via line (36) to the VRC evaporator (12) circulating heater (CH1) creates an excess of vapors (31) overhead from the evaporator, because the VRC compressor (26)
can only pass a fixed amount of steam, which amounts to about 90% of vapor boilup in the VRC evaporator (1 2) for the
described case.
The excess vapors (31) are desuperheated and routed to the purge evaporator (5) circulating heater (CH2) to supply boilup energy for that unit. In turn, overhead vapors (4) from the purge evaporator (5) are desuperheated and routed
to the brine cooled condenser (3) and used for preheating feed brine.
The following description of Figure II describes the gas turbine two stage vapor recompression evaporation unit. It
employs the same approach used in describing Figure I. All numbers in Figure I are duplicated where applicable in Figure II, and new numbering of Figire II is used for added or modified components starting with numeral (50). Significant
differences in identically numbered components in Figure II exist and are as follows:
1- The VRC compressor (26) is a two stage machine in Figure II and a single stage machine in Figure I.
2- The first VRC evaporator (VRC1) (12) operates at (3.1 Bar and 145°C) (30 psig and 293 degrees F) in Figure II
and at 1.7 Bar and 126°C (10 psig and 258 degrees F) in Figure I. There is only one VRC evaporator (12) in Figure
I.
3- In Figure II, the overhead vapors (31) from the initial VRC evaporator (12) are desuperheated and routed to the
circulating heater (CH2) of the second, lower pressure, VRC evaporator (VRC2) (55). The evaporator operates at
1.7 Bar and 126°C (1 0 psig and 258 degrees F), which conditions are substantially the same as those in the VRC
evaporator (12) in Figure I.
4- Stream (25), the VRC compressor suction in Figure II, originates at the 1.7 Bar (1 0 psig) second VRC evaporator
(55) rather than at the VRC evaporator (12) of Figure I.
5- Stream (29), the desuperheating condensate supply lines, has two additinal process connections in Figure II.
One desuperheats steam (31) exiting from the first stage of the two stage vapor compressor. The second desuperheats the second VRC evporator (VRC2) overhead stream (50).
Newly numbered components in Figure II (other than (50) and (55) mentioned earlier), are now described:
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a- Stream (54) supplies elutriating brine to the second VRC evaporator (55) and stream (52) transports salt slurry
from the second VRC evaporator to the salt recovery and processing step (1 7) in similar manner to that employed
for the VRC evaporator (12) in Figure I.
b- Stream (50) transports excess steam from the second VRC evaporator (55) to the purge evaporator (5) circulation heater (CH3). This excess steam (50) is that generated from the second VRC evaporator (55) which exceeds
the suction capacity of the two stage compressor (26). For the case depicted, stream (50) is about 60,500 PPH
(pounds per hour) of 10 psig saturated steam after desuperheating.
c- Stream (51) transports purge brine liquor from the second VRC evaporator (55) to control brine liquor impurity
concentration in VRC evaporator (55) and to supply feed brine to the purge evaporator (5).
d- Stream (53), condensate exiting the second VRC evaporator (55) crculating heater (CH2) is combined with
stream (21) and routed to the brine preheater (1 0) for heating the feed brine (9). In the two stage case, feed brine
is preheated to approximately 5,6°C (1 0 degrees F) below operating temperature in the first VRC evaporator (12)
or 139,4°C (283 degrees F).
Typical operating conditions for producing about 24910 kN per day (2500 TPD (tons per day)) of high purity chemical grade salt (99.99% NaCI) by the preferred embodiment of this invention, shown in Figure I, are given in Table I. The
typical operating conditions for producing about 29892 kN per day 3000 TPD of similar high quality chemical grade salt
by another preferred embodiment of this invention, shown in Figure II, are given in Table II.
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6
" in
DracKets:
Kgper
nour,
I Htll_fc.
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N0S- IN
1
FIG I i III DESCRIPTION
2
Brine to Brine
cooled condenser
I
4
Hot Overhead Vapors
From Purge Evaporator
to Brine Cooled
Condenser
7,8
9
I
Brine
800,000
(2>bl,U0)
56,000+
213
Desuper.
h e a t i n g " ? ? " ? / Cf0Om 6*C)
L
Condensate
'
,
216,000
140
140
f ' Q0°( ' )
11
Brine Exit BP
584,000
IL(f.fOO)
258
f r u ° c )
14
Purge Brine Feed
Liquor to Purge
Evaporator
105,000
f( i , » i £ t a \
Hi,bl<fJ
258
17
Purge Brine Liquor
Fac?SriWeil
0 - 1
( 4 - i oYfoJS
:u*v*tj
|
,
15,000
C M
228
(40,.1'C)
Salt Produced in
Salt Recovery &
Processing
(99.9974% NaCI)
209,250
(Dry Basis)
r/()\
("f**"/
19
Condensate Exit
Brine Cooled
Condenser
56,000+
Greater
Desuper7, _
% Than
heatingU^VCW 140
condensate
(60%)
20
Condensate
From Purge Evaporator
CH2
21
Condensate
From VRC Evaporator
CHI
j
46,000
238
'
Desupern
h e a t i n g f t O ^ O ) C f ^ y . *A
/
Condensate
( (
!
555,000
274
\ /
/or* lc/)l
\
(151, **0)
| ^ j y ^ ^ y
24
Condensate Return to
Brine Production
556,000
fi O 0 f\f)\
!
180
i (approx)
25
VRC Evaporator
Overhead Steam to
Vapor compressor
500,000
s ,, e >
{LI* ( 800)
:
to
PRESSURE
'
PSIG
73
\(2l.1°C)
584 , 000
(WHO)
3«5
50
Bar
Brine Inlet Brine
Preheater (BP)
16
30
Elutriating
and
POUNDS PER#,
TEMP #
HOUR FLOW
! DEGREE F.
|
w
15
tentigrades
1
'
1
1
,
239
(■^iTcC)
10
/.,,
"\
EP 0 604 718 B1
in
brackets:
kg
5
15
25
30
hour,
TABLE
NOS . IN
FIG I & II
10
per
21
32
I
Centigrades
and
Bar
<cont i nuea )
POUNDS PER ^
TEMP >
HOUR FLOW
DEGREE F.
~~
'
'
1
Excess VRC Evaporator
239
46,000+
Vapor to Purge
DesuperEvaporator
heating
r
\
C i r c u l a t i n g Heater
Condensate
[/!/lS°C/
(CH2)
(10,1*0)
1
High Pressure Steam
35,000
820
( w . s r )
fa.ao)
DESCRIPTION
33
Exhaust Steam From
Turbine
35
Steam Turbine
Generator - 1.7 MW
36
Desuperheated Steam
»™=Ev.por«=r
Natural Gas to
Combustion Gas
Turbine (CGT)
35,000
„
275+
555,000
( Z ^ 0 )
275
(w„c)
112.28
MM Btu/hr.
@80 F Ambient
-IIV.V^
to
I
\
80
/
(JGtiCj
PRESSURE
PSIG
-X"
10
{ 1 Vftar)
600
(MAh*)
,
30
30
( } _ M „ )
600
(U-l.^dr)
.
C4692I.FRM
cr u out no m
* in
brackets:
kg
per
hour,
Centigrades
and
Bar
I HDLL I 1
N0S- ™
FIG I S II
2
to
4
i
Hot Overhead Vapors
From Purge Evaporator
Censer0001611
960,000
wo;
75
* .
,
(Z5.9°C)
(3l'f$V)
(™-'*C
140
(Co°c
Brine Inlet Brine
Preheater (BP)
260,000
uiww)
700,000
(317,^0)
140
(QO'C)
11
Brine Exit BP
700,000
(zm.sio)
283
f a i l MX.)
16
Purge Brine Liquor
to Disposal Well
Facility
17
Salt Produced in
Salt Recovery &
Processing
(99.9974* NaCI)
19
Condensate Exit
Brine Cooled
Condenser
7,8,54
20
21,53
t5
/
213
?5
35
Brine to Brine
Cooled Condenser
(Bco
PRESSURE
PSIG ^
70,000
9
30
POUNDS PER
TEMP
|
HOUR FLOW sj, | DEGREE F.
DESCRIPTION
Elutriating
Brine
Condensate From
Purge Evaporator
Circulating Heater
18,000
fo j f f \ \
(S^bO)
0 - l
)
fl-l,***)
)
228
/ * ~ »}\
(st0q,4°l)
250,000
(Dry Basis)
.
ftlZ/V-OOj
1
I
fl
7 0,000
/( $- ^1 ,- 7v ^- 0m)
Greater
Than
140
[60'C)
60,500
238
(
Condensate
From VRC Evaporator
Heaters
619,000
1 7 On
(C8U,r8U/
293
/(-7
24
Condensate Return to
Brine Production
Facility
680,000
,
( ZolfiSO)
180
(approx)
fYl.l'C)
25
Evaporator
Overhead Steam to
vapor compressor
251,100
.
f, a„l l.„, 1 0 0 )
239
-
„
(^4^°C)
\)
io
/
"a \
( ^*O* O f )
EP 0 604 718 B1
in
brackets:
kg
per
TABLE
NOS. IN
FIG I & II
31
hour,
II
Centigrades
Bar
(continued)
POUNDS PER
HOUR FLOW %
DESCRIPTION
and
F i r s t VRC Evaporator
Vapor to Second VRC
307,000
TEMP *
DEGREE F.
PRESSURE
PSIG
%
275
30
(*yc>
( s m * ~ )
35,000
(-15-880)
. 320
M%.t'C)
600
(m.v-Bay)
3 5,000
309+
(CH2)
32
High Pressure
23
Exhaust Steam From
Turblne
25
Steam
S2
(sfs-WC)
tisiio)
Steam T u r b i n e
Generator - 1.6 MW
36
Desuperheated Steam
312,000
309
62
to F i r s t vrc
.
.
,
Evaporator Heater
(ft+JSZO)
(S.lB&ir)
M SWC)
' V
'
(CHI)
— — — — — — — ————————_ _ _______________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
50
Second VRC Evaporator
60,500
239
10
Excess Steam to CH3
(
( „ f c )
51
Purge Brine Feed
EvSora^96
Natural Gas to
Combustion Gas
Turbine (CGT)
105,000
258
^ l l » c )
112.28
mm Btu/hr.
§80 F Ambient
30
/< , ht)r.\
( I b . t CJ
600
.
,
(ifl-fZ&v)
C4692II.FRM
Li.TC
«f
J
to
From the data in Table I it can be deduced that the energy efficiency of the entire plant is 1,246,6 kJ/kg (536 Btu
of NaCI (99.9974% NaCI) produced in the single stage mode depicted in Figure I and Table I. From the
pound)
per
50 equivalent data in Table II, it is also apparent that the energy consumption per pound of NaCI (99.9974% NaCI) produced is 1,044.3 kJ/kg (449 Btu per pound), because more salt, i.e. 113,400 kg (250,000 pounds) per hour, is produced
in the two stage mode depicted in Figure II and Table II, than the 94,920 kg (209,250) pounds per hour produced by the
single stage plant, depicted in Figure I and Table I, employing the same amount of energy input.
This compares to the Montedison plant referred to above whose energy efficiency is approximately 2093.3 kJ/kg
55 (900 Btu per pound) of salt produced, which salt is of lower purity (99.94% NaCI) than that produced by either the single
stage or two stage modes of this invention. Thus, the single stage plant of Figure I provides a 40% reduction in energy
per ton of salt producd and the two stage plant of Figure II provides a 50% reduction in energy per ton of salt produced.
Furthermore, from Tables I and II, it can be seen that the return condensate to the brine production facility is a
majority of the solution mining water requirement for producing the feed brine, namely 83% of the water required is recy-
10
EP 0 604 718 B1
5
10
15
20
25
30
cled condensate.
Also, from Tables I and II, it can be seen that the steam turbine generator is utilized to generate 1.7 and 1.6 MW of
power, respectively, this being approximately that amount required to drive all electricity driven machinery in the evaporative salt plant, with minimal power excess for resale.
Still further, from Tables I and II, it can be seen that natural gas is the preferred fuel for the process to minimize the
environmental impact of the HRSG stack gasses.
Although we have described our invention which employs a gas turbine for the production of evaporative high purity
salt, we contemplate employing the plant design concept disclosed herein in other evaporative product plants. For
example, in the evaporation of the cell liquor produced by electrolysis of NaCI brine for the manufacture of caustic soda
and chlorine. In such application, the topping steam turbine energy could drive the chlorine and/or refrigeration compressors).
In order that our invention may be more readily understood we have described it in the foregoing description and
drawings with respect to the preferred embodiment employing solution mined brine, which is substantially saturated
with sodium chloride. It should be noted that lower concentrations of sodium chloride brine may be employed. When
using lower concentrations of sodium chloride brine, the process would not be as economical as compared to employing concentrations of sodium chloride nearer saturation, because these lower concentrations require more evaporation
of substantial amounts of water.
Furthermore, the process and apparatus of this invention are readily adapted to employing naturally occurring
brines, such as sea water, or, chemically produced brines resulting from neutralization reactions in the manufacture of
chemicals, for example as in the manufacture of chloroprene, among other chemical manufactures, which produce by
product brines. In such cases the brine usually contains a sodium chloride concentration of well below saturation.
Still further, the process and apparatus of this invention are readily adapted to be used in the conversion of existing
multiple effect evaporation salt plants, electrically driven vapor recompression plants or combinations thereof, by
employing the key components of this invention as disclosed.
It is to be understood that various modifications within the spirit and scope of our invention are possible, some of
which have been referred to above, and although we have given detailed descriptions of preferred embodiments of our
invention, by illustrating them with specific examples, we do not intend to be limited thereto, except as defined by the
following claims.
Claims
1. A method for producing high purity salt from brine in an evaporative salt plant installation which comprises:
employing the shaft energy produced by a combustion gas turbine to drive a vapor recompressor while employing the gas turbine exhaust gases in a heat recovery steam generator to produce high pressure steam,
employing this high pressure steam to drive a topping steam turbine which produces the electrical energy
requirements of the evaporative salt plant installation,
combining the discharging vapors from the topping steam turbine with the discharge vapors from the vapor recompressor,
employing the combined vapors to heat the brine in the circulating heater of at least one vapor recompression
evaporator, said vapor recompression evaporator being supplied with preheated brine to produce a salt slurry,
separating the solid salt from the mother liquor, and purging a minor portion of the mother liquor which is supplied to a purge evaporator where it is evaporated to produce a second salt slurry, recycling the major portion
of the mother liquor to said vapor recompress ion evaporator and supplying the gaseous overhead vapors to
the vapor recompressor, and
condensing the vapors produced by the purge evaporator in a brine cooled condenser where the input brine is
used as the coolant, preheated and then supplied to the vapor recompression evaporator.
35
40
45
so
55
2.
The method in accordance with claim 1 wherein the brine employed in the salt evaporative salt plant installation is
chemically produced brine.
3.
The method in accordance with claim 1 wherein the brine employed in the salt evaporative salt plant installation is
solution mined brine.
4.
The method in accordance with claim 3 wherein a single vapor recompression evaporator is used.
5.
The method in accordance with claim 4 wherein the purge evaporator is operated at substantially atmospheric
pressure.
11
EP 0 604 718 B1
5
6.
The method in accordance with claim 4 wherein the brine exiting the brine cooled condenser is further preheated
to the operating temperature of the vapor recompression evaporator.
7.
The method in accordance with claim 4 wherein a portion of the vapor recompression evaporator is fed to the steam
chest of the purge evaporator, said portion being approximately equal to the steam supplied by the topping steam
turbine, therby increasing both the capacity to produce salt and the energy efficiency of the plant installation.
8.
The method in accordance with claim 4 wherein the impurities in the brine are concentrated in the contents of the
purge evaporator and are removed from the system by returning said impurities to the earth in a disposal well facility.
9.
The method in accordance with claim 3 wherein two vapor recompression evaporators are employed in series, the
preheated brine being supplied to the first vapor recompression evaporator, partially evaporated, and then supplied
to the second vapor recompression evaporator where it is further evaporated, supplying a portion of the mother liquor from the second vapor recompression evaporator to the purge evaporator, compressing the vapors from the
second recompression evaporator, adding to the compressed vapors steam from the topping steam turbine, supplying the combined stream to the circulating heater in the first vapor recompression evaporator, the vapors from
the first vapor recompression evaporator being supplied to the circulating heater of the second vapor recompression evaporator.
10
15
20
10. The method in accordance with claim 9 wherein the purge evaporator is operated at substantially atmospheric
pressure.
25
11. The method in accordance with claim 9 wherein the brine exiting the brine cooled condenser is further preheated
to the operating temperature of the vapor recompression evaporator.
30
12. The method in accordance with claim 9 wherein a portion of the steam from the second vapor recompression evaporator is fed to the steam chest of the purge evaporator, sxaid portion being approximately equal to the stream supplied by the topping steam turbine, thereby increasing both the capacity to produce salt and the energy efficiency
of the plant installation.
35
40
45
50
55
13. The method in accordance with claim 9 wherein the impurities in the brine input are concentrated in the contents
of the purge evaporator and are removed from the system by returning said impurities to the earth in a disposal well
facility.
14. The method in accordance with claim 9 wherein a two stage vapor recompressor driven by said combustion gas
turbine is employed.
15. The method in accordance with claim 3 wherein the condensates recovered from the recompression evaporator circulating heaters, the purge evaporator circulating heater and the brine cooled condenser are used in solution mining the salt.
16. The method in accordance with claim 3 wherein substantially all steam available at atmospheric pressure in the
plant installation is condensed and employed in heat transfer operations so that nearly all waste heat produced in
the plant contributes to the efficiency of operations and conservation of the ecosphere.
17. The method in accordance with claim 3 wherein substantially all condensates produced in the evaporative plant
installation are recovered and used in the solution mining of the salt thereby conserving the amount of makeup
water needed to mine the salt.
18. The method in accordance with claim 3 wherein the sole source of energy input to the evaporative salt plant installation is the fuel fed to the combustion gas turbine.
19. The method in accordance with claim 3 wherein a vapor recompressor driven by said combustion gas turbine is
employed.
20. An evaporative salt plant installation for producing high purity salt comprised of:
a vapor recompression evaporator (12) with a circulating heater (CH1);
12
EP 0 604 718 B1
a combustion gas turbine (37) whose shaft energy drives a vapor recompressor (26) in overhead vapor communication (25) with said vapor recompression evaporator (1 2) which in turn provides heat to said steam vapor
recompression evaporator circulating heater (CH1) which includes recovery of the gas turbine exhaust heat to
generate steam which is used to drive a topping steam turbine (35) whose shaft energy drives an electrical
generator (GEN), which produces the electricity required to run the plant, and whose exhaust vapors are combined with the discharge vapors of the vapor recompressor (26), in the vapor recompression evaporator circulating heater (CH1), to produce salt;
said vapor recompression evaporator (12) being in overhead vapor connection (31) with the circulating heater
(CH2) of a purge evaporator (5) and in liquid connection (14) with the body of the purge evaporator (5), which
utilizes steam resulting from the additional boiling effected in the vapor recompression evaporator (12) by
exhaust heat recovery, to produce additional salt;
said purge evaporator (5) being in overhead vapor connection (4) with a brine cooled condenser (3), wherein
the water vapor overheads from the purge evaporator are used in said brine cooled condenser (3) to initially
preheat the input brine before final preheating, utilizing sensible heat from circulating heater condensate,
before introductoin of the brine to the vapor recompression evaporator (12).
21 . An evaporative salt plant installation in accordance with claim 20 wherein the water condensates produced by the
brine cooled condenser (3) and evaporator circulating heaters (CH1 , CH2) are recovered and routed to a brine production facility (1) which includes a solutin mining installation and a brine treating and polishing facility for use in
solution mining underground salt.
22. An evaporative salt plant installation in accordance with claim 20 combined with with a brine production facility (1)
which employs condensate recovered from overhead streams and make up water to produce purified feed brine
containing less than 5 ppm calcium, magnesium and strontium ions and less than 500 ppm sulfate ions.
23. An evaporative salt plant installation in accordance with claim 22 combined with with a disposal well facility (18),
which includes a dilution station, air cooler, tank, pump and disposal well, which allows for disposal of calcium,
magnesium, strontium and sulfate ion impurities.
24. An evaporative salt plant installation in accordance with claim 20 wherein the shaft energy of tha gas turbine (37)
drives a vapor recompressor (26).
25. An evaporative salt plant installation in accordance with claim 20 wherein the shaft energy of tha gas turbine (37)
drives a multistage vapor recompressor (25, 26) to compress the vapors from the lowest pressure vapor recompression evaporator (55) of two or more vapor recompression evaporators (12, 55) arranged in series.
26. An evaporative salt plant installation in accordance with claim 20 combined with with a brine production facility
employing chemically produced by-product brine.
Patentanspriiche
1. Verfahren zum Herstellen von Salz hoher Reinheit aus Sole in einer Eindampfungssalzanlageninstallation, welches
folgendes umfaBt:
Verwenden derdurch eine Verbrennungsgasturbine erzeugten Wellenenergie zum Antreiben eines Dampfwiederverdichters, wahrend die Gasturbinenabgase in einem Warmewiedergewinnungsdampfgenerator verwendet werden, urn Hochdruckdampf zu erzeugen,
Verwenden dieses Hochdruckdampfs zum Antreiben einer Vorschalt- bzw. Gegendruckdampfturbine, welche
die Erfordernisse der Eindampfungssalzanlageninstallation an elektrischer Energie erzeugt,
Kombinieren der Entladungsdampfe von der Vorschalt- bzw. Gegendruckdampfturbine mit den Entladungsdampfen von dem Dampfwiederverdichter,
Verwenden der kombinierten Dampfe zum Erhitzen der Sole in dem Umlauferhitzer von wenigstens einem
Dampfwiederverdichtungsver-bzw. -eindampfer, wobei der Dampfwiederverdichtungsver- bzw. -eindampfer
mit vorerhitzter Sole versorgt wird, urn eine Salzaufschlammung zu erzeugen, Trennen des festen Salzes von
dem Mutterliquor, und Reinigen eines kleineren Teils des Mutterliquors, welcher zu einem Reinigungs- bzw.
Lauterungsverdampfer zugefiihrt wird, wo er zum Erzeugen einer zweiten Salzaufschlammung eingedampft
wird, Zuruckfiihren des Hauptteils des Mutterliquors zu dem Dampfwiederverdichtungsver- bzw. -eindampfer
und Zuftihren der gasformigen Overheaddampfe zu dem Dampfwiederverdichter, und
Kondensieren der durch den Reinigungs- bzw. Lauterungsverdampfer erzeugten Dampfe in einem solegekiihl-
EP 0 604 718 B1
ten Kondensor, wo die Eingangssole als das Kuhlmittel verwendet, vorerhitzt und dann zu dem Dampfwiederverdichterver- bzw. -eindampfer zugefiihrt wird.
5
10
15
2.
Verfahren gemaB Anspruch 1, worin die in der salzeindampfenden Salzanlageninstallation verwendete Sole chemisch erzeugte Sole ist.
3.
Verfahren gemaB Anspruch 1, worin die in der salzeindampfenden Salzanlageninstallation verwendete Sole Sole
vom Aussolen von Salzstocken ist.
4.
Verfahren gemaB Anspruch 3, worin ein einziger Dampfwiederverdichtungsver- bzw. -eindampfer verwendet wird.
5.
Verfahren gemaB Anspruch 4, worin der Reinigungs- bzw. Lauterungsverdampfer bei im wesentlichen atmospharischem Druck betrieben wird.
6.
Verfahren gemaB Anspruch 4, worin die den solegekiihlten Kondensor verlassende Sole weiter auf die Betriebstemperatur des Dampfwiederverdichtungsver- bzw. -eindampfers vorerhitzt wird.
7.
Verfahren gemaB Anspruch 4, worin ein Teil des Dampfwiederverdichtungsver- bzw. -eindampfers zu dem Dampfbehalter des Reinigungs- bzw. Lauterungsverdampfers zugefiihrt wird, wobei der Teil angenahert gleich dem
Dampf ist, der durch die Vorschalt- bzw. Gegendruckdampfturbine zugefiihrt wird, so daB dadurch sowohl die
Kapazitat zum Erzeugen von Salz als auch die Energieleistungsfahigkeit bzw. der Energiewirkungsgrad der Anlageninstallation erhoht wird.
8.
Verfahren gemaB Anspruch 4, worin die Verunreinigungen in der Sole in dem Inhalt des Reinigungs- bzw. Lauterungsverdampfers konzentriert und aus dem System durch Riickfiihren der Verunreinigungen zur Erde in einer
Entsorgungsschachtanlage entfernt werden.
9.
Verfahren gemaB Anspruch 3, worin zwei Dampfwiederverdichtungsver- bzw. - eindampfer in Reihe angewandt
werden, wobei die vorerhitzte Sole zu dem ersten Dampfwiederverdichtungsver-bzw. -eindampfer zugefiihrt wird,
teilweise verdampft wird, und dann zu dem zweiten Dampfwiederverdichtungsver- bzw. -eindampfer zugefiihrt
wird, wo sie weiter eingedampft wird, wobei ein Teil des Mutterliquors von dem zweiten Dampfwiederverdichtungsver-bzw. -eindampfer zu dem Reinigungs- bzw. Lauterungsverdampfer zugefiihrt wird, die Dampfe von dem zweiten Dampfwiederverdichtungsver- bzw. -eindampfer komprimiert werden, zu den komprimierten Dampfen Dampf
von der Vorschalt- bzw. Gegendruckdampfturbine hinzugefiigt wird, wobei der kombinierte Strom zu dem Umlauferhitzer in dem ersten Dampfwiederverdichtungsver-bzw. -eindampfer zugefiihrt wird, die Dampfe von dem ersten
Dampfwiederverdichtungsver- bzw. -eindampfer zu dem Umlauferhitzer des zweiten Dampfwiederverdichtungsverbzw. -eindampfers zugefiihrt werden.
20
25
30
35
40
10. Verfahren gemaB Anspruch 9, worin der Reinigungs- bzw. Lauterungsverdampfer bei im wesentlichen atmospharischem Druck betrieben wird.
11. Verfahren gemaB Anspruch 9, worin die den solegekiihlten Kondensor verlassende Sole weiter auf die Betriebstemperatur des Dampfwiederverdichtungsver- bzw. -eindampfers vorerhitzt wird.
45
50
55
12. Verfahren gemaB Anspruch 9, worin ein Teil des Dampfes von dem zweiten Dampfwiederverdichtungsver- bzw. eindampfer zu dem Dampfbehalter des Reinigungs- bzw. Lauterungsverdampfers zugefiihrt wird, wobei der Teil im
wesentlichen gleich dem Strom ist, der durch die Vorschalt- bzw. Gegendruckdampfturbine zugefiihrt wird, so daB
dadurch sowohl die Kapazitat zum Erzeugen von Salz als auch die Energieleistungsfahigkeit bzw. der Energiewirkungsgrad der Anlageninstallation erhoht wird.
13. Verfahren gemaB Anspruch 9, worin die Verunreinigungen in dem Soleeingang in dem Inhalt des Reinigungs- bzw.
Lauterungsverdampfers konzentriert werden und aus dem System durch Zuriickfiihren der Verunreinigungen zu
der Erde in einer Entsorgungsschachtanlage entfernt werden.
14. Verfahren gemaB Anspruch 9, worin ein Zweistufen-Dampfwiederverdichter, der von der Verbrennungsgasturbine
angetrieben wird, verwendet wird.
15. Verfahren gemaB Anspruch 3, worin die Kondensate, die von den Wiederverdichtungsver- bzw. -eindampferUmlauferhitzern, dem Reinigungs- bzw. Lauterungsverdampfer-Umlauferhitzer und dem solegekiihlten Kondensor
14
EP 0 604 718 B1
wiedergewonnen werden, beim Aussolen des Salzes aus Salzstocken verwendet werden.
16. Verfahren gemaB Anspruch 3, worin im wesentlichen aller Dampf, der bei atmospharischem Druck in der Anlageninstallation verfiigbar ist, kondensiert und in Warmeiibertragungsoperationen so verwendet wird, daB nahezu alle
Abwarme, die in der Anlage erzeugt wird, zu dem Wirkungsgrad der Operationen und zur Erhaltung der Okosphare
beitragt.
17. Verfahren gemaB Anspruch 3, worin im wesentlichen alle Kondensate, die in der eindampfenden Anlageninstallation erzeugt werden, wiedergewonnen werden und in dem Aussolen des Salzes aus Salzstocken verwendet werden, so daB dadurch die Menge an Zusatzwasser, die zum Abbau des Salzes benotigt wird, erhalten bzw. bewahrt
wird.
18. Verfahren gemaB Anspruch 3, worin die einzige Quelle der Energieeingabe in die eindampfende Salzanlageninstallation der Kraft- bzw. Brennstoff ist, der zu der Verbrennungsgasturbine zugefiihrt wird.
19. Verfahren gemaB Anspruch 3, worin ein Dampfwiederverdichter, der durch die Verbrennungsgasturbine angetrieben wird, angewandt wird.
20. Eindampfende Salzanlageninstallation zum Herstellen von Salz hoher Reinheit, sich zusammensetzend aus:
einem Dampfwiederverdichtungsver- bzw. -eindampfer (12) mit einem Umlauferhitzer (CH1);
einer Verbrennungsgasturbine (37), deren Wellenenergie einen Dampfwiederverdichter (26) in Overheaddampfverbindung (25) mit dem Dampfwiederverdichtungsver- bzw. -eindampfer (12) antreibt, welcher seinerseits Warme zu dem Dampf-Dampfwiederverdichtungsver- bzw. -eindampfer-Umlauferhitzer (CH1) liefert,
welches die Wiedergewinnung der Gasturbinenabwarme zum Erzeugen von Dampf umfaBt, welcher dazu
benutzt wird, eine Vorschalt- bzw. Gegendruckdampfturbine (35) anzutreiben, deren Wel-lenenergie einen
elektrischen Generator (GEN) antreibt, welcher die zum Laufen der Anlage erforderliche Elektrizitat erzeugt,
und deren Abdampfe mit den AusstoBdampfen des Dampfwiederverdichters (26) in dem Dampfwiederverdichtungsver- bzw. -eindampfer-Umlauferhitzer (CH1) zum Erzeugen von Salz kombiniert werden;
wobei der Dampfwiederverdichtungsver- bzw. -eindampfer (12) in Overheaddampfverbindung (31) mit dem
Umlauferhitzer (CH2) eines Reinigungs- bzw. Lauterungsverdampfers (5) und in Fliissigkeitsverbindung (14)
mit dem Korper des Reinigungs- bzw. Lauterungsverdampfers (5) ist, welcher Dampf benutzt, der aus dem
zusatzlichen Sieden bzw. Kochen resultiert, welches in dem Dampfwiederverdichtungsver- bzw. -eindampfer
(12) bewirkt wird, und zwar durch Abwarmewiedergewinnung, urn zusatzliches Salz zu erzeugen;
wobei der Reinigungs- bzw. Lauterungsverdampfer (5) in Overheaddampfverbindung (4) mit einem solegekiihlten Kondensor (3) ist, worin die Wasserdampfoverheads von dem Reinigungs- bzw. Lauterungsverdampfer in dem solegekiihlten Kondensor (3) benutzt werden, urn anfanglich die Eingangssole vor dem endgiiltigen
Vorerhitzen vorzuerhitzen, wobei wesentliche Warme aus Umlauferhitzerkondensat vor der Einfiihrung der
Sole in den Dampfwiederverdichtungsver- bzw. -eindampfer (12) benutzt wird.
21. Eindampfende Salzanlageninstallation gemaB Anspruch 20, worin die Wasserkondensate, die durch den solegekiihlten Kondensor (3) und die Verdampferumlauferhitzer (CH1, CH2) erzeugt werden, wiedergewonnen und zu
einer Soleerzeugungsanlage (1) geleitet werden, welche eine Anlage fur das Aussolen von Salzstocken und eine
Solebehandlungs- und Verfeinerungsanlage fur die Verwendung beim Aussolen von Salzstocken von Untertagesalz umfaBt.
22. Eindampfende Salzanlageninstallation gemaB Anspruch 20, kombiniert mit einer Soleerzeugungsanlage (1), welche aus Overheadstromen wiedergewonnenes Kondensat und Zusatzwasser verwendet, urn gereinigte Zufiihrungs- bzw. Speisesole zu erzeugen, die weniger als 5 ppm Kalzium-, Magnesium- und Strontiumionen und
weniger als 500 ppm Sulfationen enthalt.
23. Eindampfende Salzanlageninstallation gemaB Anspruch 22, kombiniert mit einer Entsorgungsschachtanlage (18),
welche eine Verdiinnungsstation, einen Luftkiihler, einen Tank, eine Pumpe und einen Entsorgungsschacht
umfaBt, welche die Entsorgung von Kalzium-, Magnesium-, Strontium- und Sulfationen-Verunreinigungen ermoglicht.
24. Eindampfende Salzanlageninstallation gemaB Anspruch 20, worin die Wellenenergie der Gasturbine (37) einen
Dampfwiederverdichter (26) antreibt.
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25. Eindampfende Salzanlageninstallation gemaB Anspruch 20, worin die Wellenenergie der Gasturbine (37) einen
Mehrstufendampfwiederverdichter (25, 26) zum Komprimieren der Dampfe von dem Dampfwiederverdichterverbzw. -eindampfer (55) niedrigsten Drucks von zwei Oder mehr Dampfwiederverdichtungsver- bzw. -eindampfern
(12, 55), die in Reihe angeordnet sind, antreibt.
26. Eindampfende Salzanlageninstallation gemaB Anspruch 20, kombiniert mit einer Soleerzeugungsanlage, die chemisch erzeugte Nebenproduktsole verwendet.
Revendications
1. Procede pour la production de sel de haute purete a partir d'une saumure dans une installation d'evaporation pour
la production de sel, qui comprend :
I'emploi de I'energie mecanique produite par une turbine a gaz de combustion pour entramer un recompresseur de vapeur avec I'utilisation simultanee des gaz d'echappement de la turbine a gaz dans un generateur de
vapeur par recuperation de chaleur pour produire de la vapeur haute pression,
I'utilisation de cette vapeur haute pression pour entramer une turbine a vapeur de tete qui produit I'energie
electrique correspondant aux besoins de I'installation d'evaporation pour la production de sel,
la combinaison des vapeurs dechargees de la turbine a vapeur de tete avec les vapeurs de decharge provenant du recompresseur de vapeur,
I'emploi des vapeurs combinees pour chauffer la saumure dans I'element de chauffage a circulation d'au moins
un evaporateur a recompression de vapeur, cet evaporateur a recompression de vapeur etant alimente en saumure prechauffee pour produire une bouillie de sel, la separation du sel solide de la liqueur mere, et la purge
d'une partie mineure de la liqueur mere qui est fournie a un evaporateur de purge dans lequel elle est evaporee pour produire une seconde bouillie de sel, le recyclage de la plus grande partie de la liqueur mere dans cet
evaporateur a recompression de vapeur et renvoi des vapeurs gazeuses en tete dans le recompresseur de
vapeur, et
la condensation des vapeurs produites par I'evaporateur de purge dans un condenseur refroidi par de la saumure dans lequel la saumure d'entree est utilisee comme refrigerant, prechauffee et ensuite envoyee dans
I'evaporateur a recompression de vapeur.
2.
Procede suivant la revendication 1, dans lequel la saumure employee dans I'installation d'evaporation pour la production de sel est une saumure produite par voie chimique.
3.
Procede suivant la revendication 1, dans lequel la saumure employee dans I'installation d'evaporation pour la production de sel est une saumure obtenue par extraction en solution.
4.
Procede suivant la revendication 3, dans lequel il est utilise un seul evaporateur a recompression de vapeur.
5.
Procede suivant la revendication 4, dans lequel I'evaporateur de purge fonctionne a une pression pratiquement
atmospherique.
6.
Procede suivant la revendication 4, dans lequel la saumure sortant du condenseur refroidi par de la saumure est
davantage prechauffee a la temperature de fonctionnement de I'evaporateur a recompression de vapeur.
7.
Procede suivant la revendication 4, dans lequel une partie de la vapeur de I'evaporateur a recompression de
vapeur est envoyee dans la boTte a vapeur de I'evaporateur de purge, cette partie etant a peu pres egale a la
vapeur fournie par la turbine a vapeur de tete, ce qui augmente a la fois la capacite de production de sel et le rendement energetique de I'installation de production.
8.
Procede suivant la revendication 4, dans lequel les impuretes dans la saumure sont concentrees dans le contenu
de I'evaporateur de purge et sont eliminees du systeme par renvoi de ces impuretes dans la terre dans une unite
de puits de decharge.
9.
Procede suivant la revendication 3, dans lequel deux evaporateurs a recompression de vapeur sont employes en
serie, la saumure prechauffee etant fournie au premier evaporateur a recompression de vapeur, partiellement evaporee et ensuite envoyee dans le second evaporateur a recompression de vapeur dans lequel elle est soumise a
une evaporation supplemental, une partie de la liqueur mere provenant du second evaporateur a recompression
de vapeur etant envoyee vers I'evaporateur de purge, les vapeurs provenant du second evaporateur a recompres-
EP 0 604 718 B1
sion etant comprimees, les vapeurs comprimees etant additionnees de la vapeur provenant de la turbine a vapeur
de tete, le courant combine etant envoye dans I'element de chauffage a circulation dans le premier evaporateur a
recompression de vapeur, les vapeurs provenant du premier evaporateur de recompresssion de vapeur etant
envoyees vers I'element de chauffage a circulation du second evaporateur a recompression de vapeur.
10. Procede suivant la revendication 9, dans lequel le separateur de purge fonctionne pratiquement a la pression
atmospherique.
11. Procede suivant la revendication 9, dans lequel la saumure sortant du condenseur refroidi par de la saumure est
davantage prechauffee a la temperature de fonctionnement de I'evaporateur a recompression de vapeur.
12. Procede suivant la revendication 9, dans lequel une partie de la vapeur provenant du second evaporateur a recompression de vapeur est fournie a la boTte a vapeur de I'evaporateur de purge, cette partie etant a peu pi es egale au
courant fourni par la turbine a vapeur de tete, ce qui augmente a la fois la capacite de production de sel et le rendement energetique de I'installation de production.
13. Procede suivant la revendication 9, dans lequel les impuretes dans I'apport de saumure sont concentrees dans le
contenu de I'evaporateur de purge et sont eliminees du systeme par renvoi de ces impuretes dans la terre dans
une unite de puits de decharge.
14. Procede suivant la revendication 9, dans lequel il est utilise un recompresseur de vapeur a deux etages entrame
par cette turbine a gaz de combustion.
15. Procede suivant la revendication 3, dans lequel les condensats recuperes a partir des elements de chauffage a circulation des evaporateurs a recompression, I'element de chauffage a circulation de I'evaporateur de purge et le
condenseur refroidi par de la saumure sont utilises dans I'extraction en solution du sel.
16. Procede suivant la revendication 3, dans lequel pratiquement la totalite de la vapeur disponible a la pression
atmospherique dans I'installation de production est condensee et employee dans des operations de transfert thermique de telle sorte que pratiquement la totalite de la chaleur perdue produite dans I'unite contribue au rendement
des operations et a la protection de I'ecosphere.
17. Procede suivant la revendication 3, dans lequel pratiquement la totalite des condensats produits dans I'installation
de production par evaporation est recuperee et utilisee dans I'extraction en solution du sel ce qui economise la
quantite d'eau d'appoint necessaire pour extraire le sel.
18. Procede suivant la revendication 3, dans lequel I'unique source d'apport d'energie dans I'installation d'evaporation
pour la production de sel est le combustible fourni a la turbine a gaz de combustion.
19. Procede suivant la revendication 3, dans lequel il est utilise un recompresseur de vapeur entrame par cette turbine
a gaz de combustion.
20. Installation pour la production de sel par evaporation pour la production de sel de haute purete, composee de :
un evaporateur a recompression de vapeur (12) avec un element de chauffage a circulation (CH1);
une turbine a gaz de combustion (37) dont I'energie mecanique entrame un recompresseur de vapeur (26)
relie par le haut par une conduite de vapeur (25) a cet evaporateur a recompression de vapeur (12) lequel fournit a son tour de la chaleur a cet element de chauffage a circulation (CH1) de I'evaporateur a recompression
de vapeur d'eau qui comprend la recuperation de la chaleur d'echappement de la turbine a gaz pour generer
de la vapeur qui est utilisee pour entramer une turbine a vapeur de tete (35) dont I'energie mecanique entrame
un generateur electrique (GEN), qui produit I'electricite requise pour faire fonctionner I'installation, et dont les
vapeurs d'echappement sont combinees avec les vapeurs de decharge du recompresseur de vapeur (26),
dans I'element de chauffage a circulation (CH1) de I'evaporateur a recompression de vapeur pour produire du
sel;
cet evaporateur (12) a recompression de vapeur relie par le haut par une conduite de vapeur (31) a I'element
de chauffage a circulation (CH2) d'un evaporateur de purge (5) et relie par une conduite de liquide (14) au
corps de I'evaporateur de purge (5), qui utilise de la vapeur resultant de I'ebullition supplemental effectuee
dans I'evaporateur (12) a recompression de vapeur par recuperation de la chaleur d'echappement pour produire du sel supplemental;
EP 0 604 718 B1
cet evaporateur de purge (5) etant relie par le haut par une conduite de vapeur (4) a un condenseur refroidi par
de la saumure (3), dans lequel les tetes de vapeur d'eau provenant de I'evaporateur de purge sont utilisees
dans ce condenseur refroidi par de la saumure (3) pour prechauffer initialement la saumure d'entree avant le
prechauffage final, avec utilisation de la chaleur sensible provenant du condensat de I'element de chauffage a
circulation, avant introduction de la saumure dans I'evaporateur a recompression de vapeur (12).
21 . Installation d'evaporation pour la production de sel suivant la revendication 20, dans laquelle les condensats d'eau
produits par le condenseur refroidi par de la saumure (3) et les elements de chauffage a circulation (CH1, CH2)
des evaporateurs sont recuperes et envoyes vers une unite de production de saumure (1) qui comprend une installation d'extraction en solution et une unite de traitement et de polissage de saumure utile dans I'extraction en
solution de sel souterrain.
22. Installation d'evaporation pour la production de sel suivant la revendication 20, combinee avec une unite de production de saumure (1) qui emploie un condensat recupere a partir des courants de tete et de I'eau d'appoint pour
produire une saumure d'alimentation purifiee contenant moins de 5 ppm d'ions calcium, magnesium et strontium
et moins de 500 ppm d'ions sulfate.
23. Installation d'evaporation pour la production de sel suivant la revendication 22, combinee avec une unite de puits
de decharge (18) qui comprend une station de dilution, un refroidisseur a air, une cuve, une pompe et un puits de
decharge, qui permet le rejet d'impuretes de type ions calcium, magnesium, strontium et sulfate.
24. Installation d'evaporation pour la production de sel suivant la revendication 20, dans laquelle I'energie mecanique
de la turbine a gaz (37) entrame un recompresseur de vapeur (26).
25. Installation d'evaporation pour la production de sel suivant la revendication 20, dans laquelle I'energie mecanique
de la turbine a gaz (37) entrame un recompresseur de vapeur a plusieurs etages (25, 26) pour comprimer les
vapeurs provenant de I'evaporateur (55) de recompresssion de vapeur de pression la plus faible de deux ou plusieurs evaporateurs a recompression de vapeur (12, 55) disposes en serie.
26. Installation d'evaporation pour la production de sel suivant la revendication 20, combinee avec une unite de production de saumure employant une saumure sous-produite produite par voie chimique.
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