CA2000230A1

CA2000230A1 - Process and apparatus for purifying water and recovering substances dissolved in water

Info

Publication number: CA2000230A1
Application number: CA002000230A
Authority: CA
Inventors: Panagiotis Michailidis; Georgios Dialynas; Charilaos Papamatheakis; Emmanouel Kotsyphos; Ionnis Karademiris; Nicolaos Iniotakis; Claus-Benedict Von Der Decken
Original assignee: Individual
Current assignee: Forschungszentrum Juelich GmbH; DIMOTIKI EPICHIRISIS YDREUSIS KAI APOCHETEUSIS HERAKLION
Priority date: 1988-10-08
Filing date: 1989-10-05
Publication date: 1990-04-08
Also published as: EP0363838A2; RU1783987C; IL91866A0; DE3834319C2; DE3834319A1; EP0363838B1; ATE88650T1; DK469889A; JPH02131102A; DK469889D0; EP0363838A3

Abstract

PROCESS AND APPARATUS FOR PURIFYING WATER AND RECOVERING
SUBSTANCES DISSOLVED IN WATER
ABSTRACT OF THE DISCLOSURE
To purify water and recover substances dissolved in water, the water is finely divided and introduced into an inert entrain-ment gas current, whereby a specified partial pressure is set for the entrainment gas in the mixture of entrainment gas and water vapor which is formed by heating the mixture of entrainment gas and water vapor to superheat the water vapor produced. The solid particles are separated from the entrainment gas water vapor mixture. The purified mixture of entrainment gas and water vapor is cooled until the water vapor condenses, and the heat released is recycled in the process. To heat the mixture of entrainment gas and water vapor, the water to be purified is first partly evaporated by the addition of heat, and the brine formed in the partial evaporation is introduced into the entrainment gas current.
The water vapor formed during the partial evaporation, after the separation of the brine, is at least partly compressed and by giving up its heat is used on one hand to heat the entrainment gas current after the introduction of the brine to regulate the super-heated mixture of entrainment gas and water vapor, and on the other hand for the partial evaporation of the water. The purified mixture of entrainment gas and water vapor, with a condensation of the water vapor it contains, is used to preheat the water to be purified.

Description

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PROCESS AND APPARATUS FOR PURIFYING WATER AND RECOVERING
SUBSTANCES DISSOLVED IN WATER
, BACKGROUND OF THE INVENTION
1. Field of the Invention: -This invention relates to a process for purifying water and recovering substances dissolved in the water by introducing the finely divided water containing the substances into a current of inert entrainment gas. The water is introduced in such quantity that after the mixture of entrainment gas, the water formed is heated to evaporate the water and superheat the water vapor pro-duced, with the formation of a mixture of entrainment gas and water vapor free of water droplets. A specified partial pressure is achieved for the entrainment gas in the mixture of entrainment gas and water vapor. The solid particles thereby formed in the mixture -of entrainment gas and water vapor are separated from the mixture of entrainment gas and water vapor, and the remaining purified mixture of entrainment gas and water vapor is di-scharged. It is cooled to condense the water vapor, whereby the heat released is given up to a medium which is to be heated during performance of the process. An object of the invention is also an apparatus to effect the process. ~;
2. Description of the Prior Art:
A water purification process of this type is disclosed in German Laid Open Patent Appln. No. 33 37 360. That process is used for the desalinization of sea water to produce potable water. -However, the process is also used to purify industrial waste water ;~`
and to extract salts dissolved in waste water. In the process of ~-the prior art, the water to be purified is evaporated in an inert gas current and the salt is removed by superheating the water vapor formed. The salty residue is thereby precipitated in a , NHL-KFJ-33 C~ADA
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non-volatile phase. It is essential that the thermal energy required to heat the mixture of inert gas and water is obtained by cooling the water vapor to below its condensation temperature after compression of the purified mixture of inert gas and water vapor.
The heat recovered is used to heat the mixture of inert gas and water vapor. The partial pressure of the water vapor is thereby introduced into the mixture of inert gas and water vapor to be purified, as a function of the desired moisture content of the residue fraction. ~
OBJECT OF THE INVENTION ~-, An object of the invention is to obtain salts or hydrates with the necessary reduction of the partial pressure ratio and at the lowest possible superheating temperature, so that to heat the mixture of entrainment gas and water, a large temperature difference is available with a simultaneously low energy consumption, whereby both the operating costs and the investment costs for water purifi- ~`
cation and salt recovery remain acceptable.
SUMMARY OF THE INVENTION
This object is achieved by means of a process of the type described below. According to this process, the water to be `~
purified is first partly evaporated with the addition of heat. Then a concentrated brine occurs as a liquid fraction, which is finely ~`
divided and introduced into the inert entrainment gas current. The ~
water vapor formed by the partial evaporation is compressed after `
separation of the brine and is cooled in the heat exchanger on one -hand with the entrainment gas current to be heated and containing the brine, and on the other hand by heating the water to be partly evaporated. The amount of brine to be added to the entrainment gas current is determined - in the same manner as the amount of water to be purified in the process of the prior art - by the desired partial pressure ratio PSchlpt between the entrainment gas partial 2 ~
pressure PSch and the system pressure Pt of the mixture of entrain-ment gas and water vapor. The partial pressure ratio and the system pressure are regulated so that dried salts or hydrates are recovered at the separator, as desired. As a function thereof, the compression pressure for the water vapor must be selected so that ~
there is a sufficiently high dewpoint temperature of the condensing ~-water vapor to supply the necessary thermal energy for the heating of the mixture of entrainment gas and water to evaporate the water and to superheat the water vapor formed in the mixture. This -dewpoint temperature is then also the dominant factor for heating ;~
the water to be partly evaporated~ since the heat of condensation ~
of the compressed water vapor which condenses with the water during ~ -the heat exchange is also used for the partial evaporation. During the superheating of the mixture of entrainment gas and water vapor, solid particles are formed as residues of the evaporated brine.
These solid particles are separated from the mixture. The remain~
ing mixture of entrainment gas and water vapor is used as a heat source to pre-heat the water to be purified. During the heating Of '!,~' the water, the water vapor in the mixture of entrainment gas and water vapor is condensed and precipitated as pure water. Together with the condensate from the partial evaporation stage, the water ~-can be used once more as potable water or industrial water. After separation of the condensate, the entrainment gas is recycled and ~
once again charged with brine from the partial evaporation stage. ~-;
In the process according to the invention, the optimal utilization of energy with extensive recovery of the heat produced is advantageous. The encrustations caused by the precipitation of solids during the partial evaporation of contaminated water as the first stage of water purification can thereby be avoided. The grain size of the salts formed and their water content can also be regulated by an appropriate selection of the partial pressure 2 ~ 3 ~
ratio, more efficiently and effectively than with the process of the prior art.
To optimize the energy utilization, one embodiment of the invention proposes that the partial evaporation of the water to be purified be performed at least for some of the water in several heat exchanger stages. As disclosed in yet another embodiment of the invention, it is thereby appropriate, for the preheating of the contaminated water, in addition to the compressed mixture of entrainment gas and water vapor, to also use the residual heat of the compressed water vapor, which the water vapor retains even after giving up its heat and cooling during the partial evaporation ~ -~
of the water to be purified. Preference is thereby given to the use of the heat of the brine produced during the partial evaporation, and the heat of the purified water condensate from the mixture of entrainment gas and water vapor to preheat the water to be purified in yet another embodiment of the invention. ~-To reduce the risk of encrustation, a further embodiment of the invention resides broadly in that the salts are added to the contaminated water before its partial evaporation, which correspond to the type of encrustation forming substances in the water, e.g.
gypsum for the desalinization of sea water. The salts are added in a quantity such that a supersaturation of the water with the salts ;~
in question occurs. The preferred supersaturation is 10 to 30~
The salts are isolated from the brine produced after the partial evaporation of the contaminated water. A portion of the salts is -~
recycled and added to the water once again before its partial evaporation in yet a further embodiment of the invention. Instead -of the salts, or in addition to the salts, abrasive substances can also be used to prevent encrustation, as described in a yet further embodiment of the invention. The abrasive substances can be added : , :.
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to the circuit, and after the partial evaporation of the water and the production of brine, they can be removed once again. However, the abrasive substances can also be used as a permanent layer of ~-loose material, inside which the water is evaporated.
The grain size of the salts to be removed is influenced by the addition of salt germs or seeds or salt crystals in yet another ' ~
further embodiment of the invention. Here too, the salts are added -up to an amount which produces a 10 to 30~ supersaturation of the brine. The salt seeds or salt crystals used can be the same salts ~
obtained as end products after superheating of the water vapor in ~`
the mixture of entrainment gas and water vapor. They simultaneously prevent encrustations. Salt seeds are preferably added upstream of a brine pump which transports the brine, as in an additional ~-embodiment of the invention.
In another configuration of the invention, a yet additional embodiment of the invention discloses that the water vapor formed during the partial evaporation of the contaminated water in several heat exchanger stages be taken from the final and penultimate heat exchanger stages. To optimize the heat recovery, the heat required for the evaporation of the brine is obtained in the final heat exchanger stage from water vapor which was formed in the penulti-mate heat exchanger stage, while the water vapor formed in the final heat exchanger stage is again used to heat the preceding heat exchanger stages as disclosed in a further additional embodiment of the invention. To use the water vapor heat, a yet further addi-tional embodiment of the invention also discloses the use of water vapor from the penultimate heat exchanger stage at the same pressure to heat the final heat exchanger stage. For this alternative, the brine obtained in the penultimate heat exchanger stage is decom- ;~
pressed before entering the final heat exchanger stage, so that at the current water vapor temperature in the final heat exchanger ~;
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2 ~ 3 stage, the brine can be evaporated once again. If there are several heat exchanger stages for the partial evaporation of the water, it is appropriate to extract the water vapor formed after each heat exchanger stage, and to inject it if necessary together with additional steam produced in the heat exchanger stages as the heating agent. If water vapor produced in several heat exchanger stages is compressed, it is appropriate to combine the water vapor ~ ~
before its compression as disclosed in another further additional ~ -embodiment of the invention.
-~ The pure water condensate formed in addition to the salts as 3 . ~.the product of the process is collected from all the heat exchangers --disclosed in a yet further embodiment of the invention. The pure water obtained can be used as industrial or potable water.
An aspect of the invention resides broadly in a process for purifying water and recovering substances dissolved or suspended in the water, said process comprising the steps of: heating the water ~-to be purified and partially evaporating this water to be purified ~;
and thereby producing a brine and water vapor; dividing at least a portion of the brine formed by partial evaporation into at least one of: drops and droplets, and introducing the brine into an j entrainment gas stream to form a mixture of brine and entrainment gas;forming water vapor from the brine by evaporating the brine in the ; gas stream by heating the mixture of entrainment gas and brine until the water evaporates to form a mixture free of droplets of ~ `
water; separating solid particles contained in the mixture of -entrained gas and water vapor; compressing water vapor formed in at least one previous step at least partially; extracting heat from ~ ~
the compressing of the water vapor; heating the entr.ainment gas ~;
stream, at a point after addition of the brine, with the heat extracted from the water vapor during compression of the water _ - .
vapor; coDdensing at least a portion of the water vapor contained :
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2~ 3~) -in the mixture of entrainment gas and water vapor thereby producing purified water wherein heat is given off by the water vapor during j condensation; and heating the water to be purified in the first ~-~
j above step with heat given off during condensation of the water .
vapor in the immediately above step.
. Another aspect of the invention resides broadly in an apparatus for purifying water and recovering substances dissolved :~
or suspended in the water to be purified, said apparatus :~
comprising: means for introducing the water to be purified into the apparatus; at least one heat exchanger means operatively connected to said inlet means; means for at least partially vaporizing water preheated in said at least one preheater means and partially evaporating the water to be purified to produce brine and water vapor; means connecting said at least one preheater means and said means for vaporizing; means for separating the water vapor from a mixture of water vapor and brine generated by said -~
vaporizing means; means for operatively connecting said means for vapor separation.and said means for vaporizing; compressor means for compressing vapor separated by said means for separating vapor;
means for connecting said compressor means to said means for separating vapor and for leading vapor separated by said vapor separa~
tor means to said compressor means; means connected to said compressor means for conducting water vapor from said compressor ;~
means to at least one of said at least one heat exchanger means; -brine divider means for dividing said brine into at least one of:
drops and droplets, and for introducing said brine into an entrainment gas stream; means connecting said brine divider means with said separating means to deliver the brine to the brine divider means;
evaporator means for evaporating said brine; means connecting said brine divider means with said evaporation means to deliver the brine to the evaporation =eans sep r~tor =eans for separating 2 ~ 3 solid matter from said evaporated brine; and means connecting said brine divider means with said separator means to deliver the brine to said separator means.
Yet another aspect of the invention resides broadly in an apparatus to purify water and recover substances dissolved or suspended in the water to be purified, with an apparatus located on ~1 the input of a evaporator for the fine division of the water to be ~;
purified into an entrainment gas current, and with a salt separator ~1 at the output of the evaporator for solid particles which can be -;~:
formed in the evaporator by superheating the mixture of entrainment ;.
gas and water vapor produced, and with a heat exchanger connected downstream of the salt separator, which is flowed through on the -condensate side by purified entrainment gas/water vapor mixture for cooling to below the condensation temperature of the water vapor, wherein the apparatus to finely divide the water to be purified is preceded by at least one heat exchanger operated with heated water vapor to produce brine by partial evaporation of the water to be purified, whereby the apparatus for the fine division is connected :~
to a brine discharge of a separator downstream of the heat exchang- ::
er for brine production, and the water vapor discharge of the separator is connected on one hand with a compressor for the water ~ ;
vapor, whose water vapor line to an evaporator for the mixture of entrainment gas and brine, and on the other hand to a heat exchanger for the partial evaporation of the water to be purified, `.. :~
and that the heat exchanger downstream of the salt separator is connected on the evaporation side with a feed for the water to be .
purified, before its entry into the heat exchanger for brine~
production. ~ `

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BRIEF DESCRIPTION OF THE DRAWINGS
The process according to the invention and the apparatus ; i-used to effect this process, both of which are objects of this invention, are explained in greater detail on the basis of embodi- ~ ~
ments. In the accompanying drawings: i q Figure 1: Apparatus for water purification and salt recovery with partial evaporation and brine recovery in several heat exchanger stages:
~ Figure 2: Apparatus with several heat exchanger stages for s partial evaporation, whereby water vapor and brine ~-.
are separated in the final two heat exchanger stages;
Figure 3: Apparatus with several heat exchanger stages for -~
the partial evaporation and brine recovery with water vapor separation after each heat exchanger stage forming water vapor; :
Figure 4: Apparatus with several heat exchanger stages for :~
the partial evaporation and brine recovery with special water vapor compressors for the water vapor produced in the final and penultimate heat ¦ exchanger stages; -:~
Figure 5: Data for the performance of the process for an apparatus for the recovery of pure water and salt as illustrated in Figure 1, Embodiment la;
Figure 6: Data for the performance of the process for an - apparatus as illustrated in Figure 1, Embodiment lb;
¦ Figure 7: Data for the performance of the process for an apparatus for the recovery of pure water and salt as illustrated in Figure 2, Embodiment 2.

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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 is a flow diagram of an apparatus for the recovery of pure water and salt from sea water. The sea water to be proces-sed is introduced into the apparatus by means of an intake 1 by a pump 2 and preheated in heat exchangers 3 and 4. The quantities of sea water flowing through the heat exchangers can be regulated by means of valves 5, 6, 7 and 8. The valves are installed in sea water lines 9, 10 and 11 connected in parallel to the heat ex-changers. A portion of the sea water heated in the heat exchanger 3 can thus be routed so that it does not flow through the heat exchanger 4. When the valve 6 is open, a portion of the sea water flows through the sea water line 9 directly to the heat exchanger 12, in which a partial evaporation of the sea water takes place.
When the valve 13 is closed, the sea water preheated by the heat exchangers 3 and 4 flows for further preheating to another heat exchanger 14, before it, together with the mixture of water vapor and brine discharged from the heat exchanger 12, is conducted in a collecting main 15 to the heat exchanger 16. The valve 13 is located in a bypass 17 between the feed line 18 to the heat ex-changer 14 and the sea water line 9 which leads to the heat ex-changer 12. The quantity of sea water flowing to the heat exchanger ~-14 can be regulated by means of the valve 13. -~
In the heat exchanger 16, in the apparatus illustrated in Figure 1, the partial evaporation of the sea water takes place up to a specified value, e.g. up to 90Z of the quantity of water. The water vapor formed is transported together with the brine produced via the brine and water vapor line 19 carrying brine and water vapor to a separator 20, in which brine and water vapor are separ-ated from one another. In the separator 20, in the apparatus illustrated in Figure 1 - in addition to brine and water vapor -gypsum added in this embodiment is separated, which is transported '. ;~
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as sludge by means cf a feed pump 21, which transports the gypsum --in a feedback line 22 into the circuit, and pumps into the collect-ing main 15, in which the gypsum is mixed with the sea water even before it enters the heat exchanger 16, to prevent encrustations in the heat exchanger 16. The gypsum prevents the salts from becoming encrusted on the walls of the heat exchanger tubes. Instead of gypsum, other salts could also be added, which correspond to the encrustation forming substances which are contained in the sea water. Principal among such salts is CaCO3.
Brine separated in the separator 20 from the water vapor is transported to a brine discharge 23. By means of an appropriate setting of valves 24, 25 and 26 the brine can be conducted through a brine branch line 27 at least partly as a heat medium to the heat exchanger 4, before it is injected by a brine pump 28 via a brine `
feed 29 into an entrainment gas current. The entrainment gas current flows in an entrainment gas line 30 to a evaporator 31, in ~;
which the brine carried by the entrainment gas evaporates and the ' water vapor formed is superheated. The entrainment gas used in the embodiment is dry air, but gases other than air can also be used, as long as they do not chemically react substantially with the water vapor and the salt products to be recovered, and therefore ;
exhibit inert behavior with regard to the products to be recovered in the apparatus, e.g. argon, nitrogen, helium and CO2.
The brine intake line 29 empties in an apparatus 32 for the fine division of the brine in the entrainment gas. In this embodi-ment, a spray nozzle is used as ~he apparatus for the fine division, and is installed in the entrainment gas line 30 ahead of the evap-orator 31 or immediately at the mouth of the entrainment gas line into the evaporator. In the evaporator 31, dry salts or hydrates are formed when the water vapor is superheated, as a function of the partial pressure ratio of the entrainment gas in the entrain-NHL -KFJ - 3 3 C~NADA
2~Q~3q) ment gas water vapor mixture formed to the total pressure therof.
These components are transported in the mixture of entrainment gas and water vapor in a transport line 33 to the salt separator 34, ~-and there are separated as a product from the mixture of :~
entrainment gas and water vapor. The mixture of entrainment gas :
and water vapor is transported in an entrainment gas/water vapor line 35 by a feed blower 36 to the heat exchanger 14, in which the :
water vapor in the mixture of entrainment gas and water vapor is condensed, and gives up its heat to the sea water flowing through the heat exchanger 14. The condensate flows in an entrainment ::
gas/condensate line 37 to a condensate separator 38, which -separates entrainment gas and condensate, and removes the pure ~.
water obtained via a condensate line 39, which is followed by the additional cooling of the condensate on the heat transfer medium ~;
side of the heat exchanger 3. The purified water is transported via a water line 40 to potable or industrial water reservoirs, which are not shown in Figure 1. ~
The entrainment gas separated from the condensate in the : ~.
condensate separator 38 is decompressed by means of a throttle 41 and returned in the entrainment gas line 30 in the circuit, for the addition of brine via the apparatus 32 upstream of the evaporator 31. .
The water vapor, which is separated from the brine by the separator 20, is sucked through a water vapor discharge 42 by a compressor 43 and there compressed. The compressed water vapor is ~:
used as the heat transfer medium for the heat exchanger 16 and evaporator 31, and is transported either via a water vapor line 44 to the heat transfer medium side of the heat exchanger 16 for the partial evaporation of the sea water, or via a water vapor line 45 to the heat transfer medium side of the evaporator 31 for the brine evaporation and superheating of the water vapor. Before entering the heat exchanger 16, another evaporator 46 is introduced, which ~
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additionally heats the water vapor if necessary~ and in particular forms water vapor when the apparatus is being started up. For this purpose, the evaporator 46 has a water feed not shown in Figure 1.
The quantities of water vapor flowing through the heat exchanger 16 and the evaporator 31 are adjusted by means of a valve 47 in the water vapor line 45. The water vapor condenses in the heat exchang-er 16 and in the evaporator 31. The condensate flows at boiling temperature in lines 48 and 49 from the heat exchanger 16 and evaporator 31, and is transported in a water vapor/condensate line 50 for further surrender of heat to the heat exchanger 12. From the heat exchanger 12, the condensate flows in a condensate line 51 to the water line 40, and after decompression by means of valve 52, is transported together with the other purified water obtained in the apparatus to the potable or industrial water reservoirs refer-red to above.
The salt recovered in the salt separator 34 is extracted by means of a salt line 53 to salt storage tanks not shown in Figure 1. From the salt line 53, a salt seed feed line 54 leads to the brine line 29. The salt seed feed line 54 empties into the brine line 29 ahead of the brine pump 28, so that the salt seeds are distributed as uniformly as possible in the brine. The salt seeds influence the precipitation and grain growth of the solid particles formed in the evaporator 31 when the water vapor is superheated.
All the flows in the apparatus are regulated by means of the above-mentioned valves so that the energy required for recovery of purified water and salt is recovered as completely as possible in the apparatus itself. For this purpose, there are also the heat exchangers 3, 4 and 12, in which on the one hand the heat of the brine, and on the other hand the heat of the condensate produced, are used to preheat the sea water. For the partial evaporation of the sea water, there are heat exchangers 12 and 16, together with 2 ~ NHL-KFJ-33 CANADA
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heat exchangers 3, 4, 12 and 14, used to preheat the sea water.
In addition to the recovery of the energy, the principal advantage of the apparatus according to the invention compared to the apparatus disclosed in German Laid Open Patent Appln. No 33 37 360 is that the required compression pressure on the heat transfer medium side of the evaporator 31 is not determined on the basis of the current system pressure in the mixture of entrainment gas and water vapor, and of the pressure difference to be overcome between the system pressure and the compression pressure, but can be achieved on the basis of the pressure in the water vapor/brine line 19. The pressure in the water vapor/brine line 19 corresponds to the pressure produced in the pump 2 in the sea water lines 9, 10, 11, in the feed line 18 and accordingly in the collecting main 15.
This pressure is higher than the system pressure and thus reduces the pressure difference to be overcome by the compressor 43, in contrast to the apparatus disclosed in German Laid Open Patent Appln. No. 33 37 360. The pressure difference to be overcome by ~-the feed blower 36 is also relatively low, since essentially only the pressure losses which occur during transport of the mixture of entrainment gas and water vapor must be offset. In the apparatus ~;~
according to the invention, therefore, lower powered compressors and pumps can be used than in the apparatus of the prior art.
Figure 2 illustrates an apparatus for the recovery of ~ -~
purified water and salt from sea water, in which there are several heat exchanger stages for concentration of the brine. In the schematic flow diagram of the apparatus in Figure 2, the same -;~
numbers as in Figure 1 have been used to identify those components ;~-of the apparatus which have the same technical function as the components of the apparatus illustrated in Figure 1 and described above. To identify the component of the apparatus illustrated in Figure 2, the index letter "a" has been added to the number used NHL-KFJ-33 C~NADA
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for the description of the component described in Figure 1. All the components in Figure 2 identical to those in the apparatus illustrated in Figure 1 have therefore been distinguished by the ~ letter "a" from components which are new in Figure 2, and therefore 3 have no index.
In the apparatus illustrated in Figure 2, the same components as in the apparatus illustrated in Figure 1 are used to introduce and preheat the sea water up to the first evaporation in the heat exchanger 12a. The sea water is thus preheated in the heat exchanger 3a by the condensate from the condensate separator 38a, in the heat exchanger 4a by the brine extracted in the separator 20a, and in the heat exchanger 14a by the mixture of entrainment ~;
gas and water vapor after the separation of the solid particles formed by the superheating of the water vapor in the salt separator 34a. In the heat exchanger 16a, a portion of the sea water introduced into the apparatus is evaporated, and as a heating medium for this evaporation on the heat transfer medium side, water vapor is used which was separated from the brine in the separator 20a. From the separator 20a, as in the apparatus illustrated in Figure 1, the water vapor flows through a heater 46a, which can serve as a reheater, but which serves primarily as an evaporator when the apparatus is started. In contrast to the apparatus illustrated in Figure 1, however, the water vapor is not compressed before it flows via a water vapor line 44 to the heat transfer medium side of the heat exchanger 16a. The condensate, formed in the heat exchanger 16a, flows via the discharge line 48a into the water vapor/condensate line 50a and after surrendering its heat in the heat exchanger 12a flows out of the apparatus via the condensate line 51a and the water line 40a. The mixture of ~ entrainment gas and water vapor is used as the heating medium in ?
~ the heat exchanger 14a.
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Before the sea water flowing in the collecting main 15a at or slightly below boiling temperature enters the heat exchanger 16a, in the same manner as in the apparatus illustrated in Figure 1, the gypsum separated from the brine in the separator 20a is introduced via a return line 22a, to prevent encrustations in the tubes of the heat exchangers used for the partial evaporation of the sea water.
In contrast to the apparatus illustrated in Figure 1, in the apparatus illustrated in Figure 2 the water vapor extracted from the separator 20a is not compressed before it flows through the heat exchanger 16a on the heat transfer medium side. There are also two heat exchanger stages for the production of brine, whereby the first of these stages is formed by the heat exchanger 16a and ~
the second stage by the heat exchanger 55 which is in the circuit ~-downstream of the heat exchanger 16a. After the partial evaporation in the heat exchanger 16a, the brine conducted via the water ~;
vapor/brine line 19a is separated from the water vapor in a separa~
tor 56 and is pumped by means of a brine pump 57 via a brine line i to the heat exchanger 55. In the heat exchanger 55, the brine is j concentrated, before it is again separated in the separator 20a c from the water vapor formed. A water vapor/brine line 59 leads from the heat exchanger 55 to the separator 20a.
Water vapor separated from the brine by the separator 56 is extracted by a compressor 60 by means of the intake line 61 and compressed. The compressed water vapor is used in the apparatus ~;
illustrated in Figure 2 as the heating medium for the heat exchang- ~;
er 55 and evaporator 31a. The amount of water vapor which flows through the heat exchangers and evaporators is regulated by means of a flow controller 47a. In both of the components described above, in the heat exchanger 55 and in the evaporator 31a, the water vapor is cooled to condensation temperature and transported ~, ;~.':

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by means of discharges 62, 63 from the heat exchanger and evaporator to a common condensate line 64. The water vapor is decompressed in the condensate line 64 by means of a relief valve, 65 and together with the condensate flowing out of the heat exchanger 16a is conducted to the heat exchanger 12a in the water vapor/condensate line 50a which after feeding the decompressed condensate carries boiling water from the condensate line 64.
On account of the pressure reduction by means of the relief valve 65 and the corresponding low pressure in the condensate line 51, there need be no additional pressure relief in this line before the introduction of the condensate into the water line 40a. In the apparatus illustrated in Figure 2, however, a pressure reduction is necessary for the condensate flowing in the water line 40a, by means of a pressure relief valve 66.
The differences between the systems illustrated in Figures 1 and 2 can be summarized as follows:
First, in Figure 2 an additional heat exchanger 55 is used ~ . ~
for the additional concentration of the brine formed in the heat exchanger 16a. Moreover, the water vapor separated upstream of the heat exchanger 55 in the separator 56 is compressed and used as a heating medium on one hand in the heat exchanger 55, and in the other hand in the evaporator 31a to heat the mixture of entrainment gas and brine. The water vapor separated in the separator 56 and compressed thus flows through to the heat transfer medium side of both the evaporator 31a and the heat exchanger 55. An additional difference is on the heat transfer medium side of heat exchangers 16a and 12a: the water vapor flows through the heat exchangers at a low pressure level. This configuration of the apparatus illus-trated in Figure 2 makes possible a better utilization of the heat of the water vapor obtained during the partial evaporation and the production of brine from the sea water.

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Figure 3 shows a flow diagram of an apparatus for the production of pure water and salt from sea water, in which water vapor is extracted after each heat exchanger in which water vapor is formed during the partial evaporation of the sea water and brine production. In Figure 3, once again, all the components which have the same function as the components of the systems illustrated in Figures 1 and 2 are designated by the same number, but the compon- ~ I
ents in Figure 3 are identified with the index "b". Components added in the apparatus illustrated in Figure 3 again have reference numbers without an index.
The apparatus illustrated in Figure 3 is distinguished from the apparatus illustrated in Figure 2 first by the additional separator 67, which is introduced into the circuit after the heat exchangers 12b and 14b, to separate the water vapor in the collect~
-ing main 15b from the initial, still not-very-concentrated brine.
The brine collecting in the separator 67 is extracted by a brine pump 68 and transported in a brine line 69 to the heat exchanger 16b. The brine is further evaporated in the heat exchanger 16b and after separation of the water vapor thereby formed by the separator 56b, flows to the heat exchanger 55b. In contrast to the apparatus illustrated in Figure 2, however, the brine is not brought to a higher pressure before its hot-side entry into the heat exchanger 55b, but on the contrary is decompressed by means of a pressure relief valve 70.
The heat exchanger S5b forms the final heat exchanger stage ~
for the partial evaporation of the sea water and for the concentra- ~ -tion of the brine. The brine is separated from the water vapor in `~
the separator 20b. It flows at least partly through the brine discharge 23b and the brine branch line 27b on the heat transfer ~-medium side to the heat exchanger 4b for preheating of the sea water fed to the apparatus, and after the introduction of salt , :,.

; ' :`'' ' 2~0Q~ NHL-KFJ-33 C~AD~

seeds is pumped through the salt seed input 54b by means of the brine pump 28b to the apparatus 32b, and is sprayed into the entrainment gas current. The mixture of entrainment gas and brine formed in this manner is evaporated in the evaporator 31b and superheated so that the substances dissolved in the sea water are precipitated as solid particles which are recovered in the salt separator 34b. The mixture of entrainment gas and water vapor purified of the solid particles is conveyed by the feed blower 36b through the entrainment gas/water vapor line 35b to the heat exchanger 14b. In the heat exchanger 14b, the water vapor is condensed, giving up its heat to the sea water to be preheated, and separated from the entrainment gas as condensate in the separator 38b. After decompression in the throttle 41b in the entrainment gas line 30b, the entrainment gas is returned to the circuit to deliver brine to the evaporator 31b.
In addition to the additional separator 67 which is located downstream of the heat exchangers 12b and 14b, the apparatus illus-trated in Figure 3 differs from the systems illustrated in Figures 1 and 2 by a variation in the heating of the heat exchangers 16b, 55b and of the evaporator 31b. Of course, the heat exchanger 16b and the evaporator 31b are again heated, as in the apparatus illus-trated in Figure 1, by water vapor which is extracted from the sep-arator 20b and compressed by the compressor 43b. In addition to the water vapor extracted from the separator 20b, however, the compressor 43b also extracts the water vapor separated in the separator 67 by means of a water vapor line 71.
The heat exchanger SSb, as in the apparatus illustrated in Figure 3, is heated by water vapor which is separated in the separ~
ator 56b from the brine formed in the heat exchanger 16b. The~
water vapor is introduced withou~ compression through a water vapor I ~-line 72 on the heat transfer medium side into the heat exchanger ~-~

-~:

~ Z~G~3~ NHL-KFJ-33 CANAD~ .
,,j 55b So that a sufficient temperature gradient for evaporation of the brine can also be obtained in the heat exchanger 55b without compression, the brine flowing out of the separator 58b and serving as the heat transfer medium, is decompressed by means of the pressure relief valve 70 before entering the heat exchanger.
The condensate formed in the heat exchangers 16b and 55b and in the evaporator 31b on the heat transfer medium side during cooling of the water vapor is collected in the apparatus -;
illustrated in Figure 3 like in the apparatus illustrated in Figure ~ 2 in a water vapor/condensate line 50b. In the apparatus r~ illustrated in Figure 3, however, the condensate flowing in the ;~
- discharge lines 48b and 49b is also decompressed by means of throttles 73, 74, before the condensate is combined with the condensate being discharged from the discharge point 62b. During the decompression of the condensate, water vapor is formed, and boiling conditions are still present in the water vapor/condensate line 50b. The boiling water flows as a heating medium to the heat exchanger 12b and is cooled there to below the condensation temperature. The condensate formed flows in the condensate line 51b. It is combined with the condensate being discharged by the heat exchanger 3b. The latter must also be decompressed by means 3~ of pressure relief valve 66b as in the apparatus illustrated in ;..
Figure 2.
The apparatus illustrated in Figure 3 differs from the systems described above on one hand as a result of the additional ''J, separator 67 after the first partial evaporation of the sea water in the heat exchanger 12b, and as a result of the heat exchange operating at a low pressure level in the heat exchanger 55b. Both .~ ~ -~, of the media flowing through the heat exchanger, i.e. the water ;~
vapor serving as the heat transfer medium and the brine to be ~
evaporated, are at a lower pressure level than is the case at the ;~-,..

] ' ,............................................................................ ~

'! Z ~ QZ ~ O NHL-KFJ-33 heat exchanger 55 in the apparatus illustrated in Figure 2.
Figure 4 illustrates an apparatus for sea water desaliniza-tion which, in terms of the utilization of the heat of the water vapor formed during the multi-stage partial evaporation, combines the characteristics of the systems illustrated in Figures 2 and 3 with one another. In Figure 4, once again, all the components which have already been used in other systems are designated by the same number, but the components unique to the apparatus illustrated in Figure 4 are identified with the index "c".
While in the apparatus illustrated in Figure 2, the brine . discharged from the separator 56 is pumped out by means of a brine i, pump 57 and flows through the heat exchanger 55 at elevated pres-sure, and while the water vapor formed in this heat exchanger during the further evaporation of the brine is conducted at the same pressure level to the heat exchanger 16a after separation from the brine in the separator 20a, in the apparatus illustrated in Figure 4, the brine extracted from the separator 56c is subjected to a decompression by means of a pressure relief valve 70c as in the apparatus illustrated in Figure 3, and the water vapor recovered ' at this same pressure level in the separator 20c is compressed by means of a compressor 75, before the water vapor is introduced through a water vapor line 44c on the heat transfer medium side into the heat exchanger 16c. The compressors 75 and 60c produce ~
final pressures of different levels. The function of at least the ~;
j compressor 60c corresponds to compressor 60 in the apparatus illustrated in Figure 2. It is therefore necessary to decompress, ~-before the combining of the condensates which are dischaFged from ---the heat exchangers 16c and 55c and from the evaporator 31c. For -t~.is purpose, in the apparatus illustrated in Figure 4, there is a ~
relief valve 65c in the condensate line 64c and an additional ~-throttle valve 76 in the discharge line 48c. The condensate is -~

21 ~

.
.

; 2~ NHL-KFJ-33 C~NADA
i decompressed by the two above-mentioned valves so that boiling conditions once again are present in the water vapor/condensate line 50c. :
In the apparatus illustrated in Figure 4, the heat produced during the necessary evaporation of the sea water is optimally utilized, and by means of two compressors, an average pressure level is produced in the portions of the system which transports ~
~! the water vapor obtained during the partial evaporation of the sea :~:
water as the heat is carried to the heat exchangers and to the evaporator. This eliminates the use of expensive high-pressure ~
components. ~;
~j Embodiments with operating data to effect the process are illustrated in Figures 5, 6 and 7. Figures 5 and 6 illustrate an apparatus of the type illustrated in Figure lj and Figure 7 an ~-apparatus of the type illustrated in Figure 2. In all the Figures 5, 6 and 7, the material currents inside the systems are marked by arrows, and by flow quantities, m, in kg/h, pressures, P, in bar -:-and temperatures, T, in C. The data of the material currents are always entered on the portion of the line in question, whereby the ~;~
flows are always indicated at the beginning of a line section, and if an extraction takes place, at the end of a line section. The ~:-material currents are also distinguished from one another by addi-tional indices. For sea water and brine the index is "S", for water vapor "D", for condensate "C", for the mixture of entrainment gas and water vapor "GD", or "L" for entrainment gas, "D" for water ..
vapor, and "Salz" as the index for salt.
The temperature data for those heat exchangers in which the sea water evaporates at the boiling temperature TS (TS = boiling temperature of salt water under the conditions at the output of the heat exchanger in question), or water vapor condenses on the heat * . ~
transfer medium side at a constant condensation temperature TC

22 ~;

i NHL-KFJ-33 CAN~DA
~ 2~?~Q;~3~) (TC = condensation temperature of the water vapor), correspond to . the boiling and condensation temperature respectively at the corre-sponding pressure. The temperature change in the heat exchangers for the substance in question is calculated from the difference between the indicated input and output temperatures on the heat exchangers. The same is true for the evaporators in the embodi-ments illustrated in Figures 5, 6 and 7. On one hand, the boiling temperature TS of the brine in the entrainment gas/brine mixture is indicated (in Figure 5, for example, TS = 155.5C), and on the 3~ other hand the output temperature of the mixture of entrainment gas and water vapor from which the superheating of the water vapor in the mixture of entrainment gas and water vapor results (in Figure 5, for example, TGD = 170C). The water vapor entering on the heat transfer medium side (in Figure 5, TD = 208C) condenses in the evaporator (in Figure 5 TC = 165.5C) and exits as condensate at a temperature below the condensation temperature (in Figure 5, for example, at TC = 164C).
~ The current pressure in the equipment and lines of the - system in Figures 5, 6 and 7 is always indicated downstream of compressors or pumps. The pressure always corresponds to the operating pressure, i.e. for gas mixtures to the system pressure Pt. The pressure indicated downstream of the compressors and pumps ~---~ then applies for the entire following system area, unless the pressure is reduced by relief valves or throttles. The subsequent ;--pressure is then indicated downstream of the valves or throttles.
Thus, for example, in the embodiment illustrated in Figure -~
5, the sea water is pumped into the system by the water pump 2 at a pressure PS = 5 bar. This pressure applies for the entire system area in which the sea water is partly evaporated and the brine is ~ produced. The water vapor separated from this system area by the Y~; separator 20 is then brought by the compressor 43 to a pressure of ~1 2 .. , , , - 2~Q~30 NHL-KFJ-33 C~ADA
.. .
PD = 7.1 bar and under this pressure is transported to the heat transfer medium side of the heat exchanger 16 and to the evaporator 31. The condensate formed at this pressure is decompressed, before it is combined with the rest of the condensate obtained in the apparatus. The relief valve 52 is used to decompress the conden sate.
The temperatures indicated in Figures 5, 6 and 7 and the pressures shown do not take into account heat losses or pressure losses which occur in the system during transport of the components ~ ;
therof. With appropriate insulation and design of the apparatus, however, such losses are of minor importance.
In the embodiment illustrated in Figure 5, a quantity of brine of ~S = 1,624 kg/h is introduced into the entrainment gas circuit. This quantity of brine in the subsequent mixture of entrainment gas and water vapor leads to a partial pressure ratio PSch/pt = 0.2. At this partial pressure ratio and the prevailing system pressure Pt=5.28 bar, for the brine in the entrainment gas/brine mixture, there is a boiling temperature TS = 155.5C.
It is thereby taken into account that on account of the partial evaporation of the sea water, the brine has been concentrated to 10% of the total quantity of sea water input, and has a salt content which leads to a 10C increase in the boiling point (the ~--boiling point of pure water at Pt = 5.28 bar is TS = 145.5C).
The mixture of entrainment gas and wa~er vapor freed of the v solid particles is extracted from the separator 34 by the feed `-blower 36 and brought to a system pressure Pt = 6 bar. The system -`
pressure Pt = 6 bar is set at the charging point of the entrainment gas circuit. By means of a pump or from a compressed air reser~
voir, air is introduced into the apparatus at a pressure up to 6 ~
bar. ;;
At this pressure, then, the mixture of entrainment gas and ':

NHL-KFJ-33 CAN~DA
2~ 3 ~

~ water vapor then flows through the heat exchanger 14, in which the j water vapor of the mix~ure of entrainment gas and water vapor condenses at a temperature of TC = 150.4C. The entrainment gas separated in the separator 38 from the condensate is then decom-pressed by the throttle 41 back to the system pressure Pt = 5.28.
~x In the separator 38, condensate is obtained with a throughput mC =
1,000 kg/h, and is transported at PC = 6 bar via the heat exchanger 3 to the output of the system.
.~ The brine extracted from the separator 20 flows at a pressure of PS = 5 bar through the heat exchanger 4 and is decompressed - before the addition of salt seeds via the salt seed input 54 by ~; means of the valve 26 to normal pressure PS = 1 bar. A correspond--~ ing pressure reduction is also achieved by means of the valve 25 After the addition of the salt seeds, the brine is then recompres-sed to a higher pressure by means of the brine pump 28. The brine is transported at a pressure of PS = 8 bar to the input of the ~
evaporator 31 and there is sprayed into the entrainment gas by -~~
means of the injection nozzle, which serves as an apparatus 32 for the fine division of the brine in the entrainment gas mixture. The ~;
`;'! entrainment gas pressure - the system pressure Pt as already mentioned - Pt = 5.28 bar. As the salt product, with the amount of ;- sea water of ~S = 10,440 kg/h put into the system, mSalz = 424 kg/h ~-of salt is obtained. Thereby, a total of mSalz = 624 kg/h are ~, separated by the separator 34. Of this amount of salt, however, -~
mSalz = 200 kg/h is recycled in the salt seed input 54 as salt seeds into the brine.
~t The embodiment illustrated in Figure 6 differs from the embodiment illustrated in Figure 5 only in the entrainment gas ~-, circuit. In the apparatus illustrated in Figure 6, a system `9 pressure of Pt = 4.6 bar is set for the mixture of entrainment gas and brine or for the mixture of entrainment gas and water vapor.
. ~

25. -. . .

2~GX3~ NHL-KFJ-33 CANADA

I With the same amount of brine of mS = 1,624 kg/h, which is intro-j duced into the entrainment gas ahead of the evaporator 31, there is a partial pressure ratio of PSchlpt = 0.2 in the mixture of entrain-ment gas and water vapor. For the brine from which 90~ of the sea water has been evaporated, in the same manner as in the embodiment illustrated in Figure 5, there is a boiling temperature of TS
150.5C. The mixture of entrainment gas and water vapor leaves the evaporator 31 after superheating of the water vapor at a temperature of TGD = 165C. The dry solid particles formed by this superheating -in the mixture of entrainment gas and water vapor are separated in the separator 34. The amount of salt separated usually equals the amount of salt obtained with the same quantity of sea water in the embodiment illustrated in Figure 5.
The remaining entrainment gas/water vapor mixture is extracted ~
from the separator 34 and brought by the feed blower 36 to a pres- --sure of Pt = 5.2 bar. As a result of this compression of the --mixture of entrainment gas and water vapor, the temperature in the -;-mixture increases to TGD = 181C. ~ -`
At a system pressure of Pt = 5.2 bar, there is a condensation temperature TC = 144.9C for the water vapor in the mixture of ;
entrainment gas and water vapor. At this temperature, the water vapor condenses in the heat exchanger 14. The condensate is cooled * . :~ ' to a temperature TC = 75C in the heat exchanger 14 and separated from the entrainment gas in the separator 38. As in the embodiment ~
illustrated in Figure 5. ~C = 1,000 kg/h of condensate is obtained. ~`
The entrainment gas flows back from the separator 38 in the circuit, whereby in the throttle 41, the pressure is reduced from Pt = 5.2 bar to Pt = 4.6 bar.
j On account of the somewhat lower initial temperature of the condensate at the separator 38 of TC = 75C, the sea water in heat exchanger 3 cannot usually be heated as much as with the process ; NHL-KFJ-33 C~NA~
21~?~Q~3~) illustrated in Figure 5. This is compensated by a smaller through-put for the sea water through the heat exchanger 3 and a lower temperature difference. While as illustrated in Figure 5, an amount of sea water ~S = 6,290 kg/h can be preheated from TS = 20C
to TS = 28C, as illustrated in Figure 6 only an amount of sea , water ~S = 6,245 kg/h can be heated from TS = 20C to TS = 27.5C. ~-s With this amount of sea water, after passage through the heat -. exchanger 14, however, there is a temperature at its output which varies only negligibly from the sea water temperature at the output of the heat exchanger 14 illustrated in Figure 5. In Figure 5, the sea water - at a condensation temperature of TC = 144.9C on the , condensation side of the heat exchanger - is heated to a temperature TS = 140.9C, and in Figure 6 - at a condensation temperature of TC = 150.4C on the condensation side - to a temperature of TS =
140.5C. These differences have no effect after the combining of the partial currents of the preheated sea water behind the heat ;~-exchangers 12 and 14 for the thermal status of the sea water at the input of the heat exchanger 16. In a comparison of the embodiments illustrated in Figures 5 and 6, the system pressure differences in ;;
the entrainment gas circuit are important: in the apparatus illus-trated in Figure 5, a system pressure Pt = 6 bar prevails in the entrainment gas circuit, or after decompression Pt = 5.28 bar. In the apparatus illustrated in Figure 6, the system pressure is Pt =
5.2 bar or Pt = 4.6 bar. At a lower system pressure in the entrain~
ment gas circuit, all other parameters being equal, there is a larger temperature difference available in the heat exchangers 31 ~--and 14 for heat transmission. In the embodiment illustrated in Figure 6, the temperature differences are 5C higher than in the embodiment illustrated in Figure 5, without having to add more energy when the system is in operation.
Figure 7 indicates operating data for an apparatus for the -, ~ 2 ~ ~Q~ NHL-KFJ-33 CANA~
"' desalinization of sea water as illustrated in Figure 2. Even if the quantity of sea water processed hourly in this apparatus of ~S
= 10,440 kg/h and thus the product quantity for pure water ~C =
10,000 kg/h and for salt mSalz = 424 kg/h have not changed from the embodiments illustrated in Figures 5 and 6, the apparatus still -operates more economically, with a more favorable utilization of the thermal energy required for the recovery of purified water and salt.
The sea water is again pumped into the apparatus by the water pump 2a at PS = 5 bar, and is preheated by the water vapor ~-and condensate obtained in heat exchangers 3a and 12a, and by the mixture of entrainment gas and water vapor in the heat exchanger -14a and by the brine in the heat exchanger 4a so that the sea water begins boiling at a temperature of TS = 152.6C in the heat ex-changer 16a. In the heat exchanger 16a, a 50% partial evaporation of the sea water takes place, and the water vapor and brine thereby formed are separated from one another in the separator 56.
The water vapor is extracted from the separator 56 by the , ,.
compressor 60 and compressed to a pressure of PD = 8.4 bar. The temperature of the water vapor thereby increases to TD = 224C. Of the total compressed vapor quantity ~D = 5,122 kg/h, ~D = 3~900 kg/h are used as the heating medium for the heat exchanger 55, and the remaining vapor quantity of ~D = 1j222 kg/h flows through the evaporator 31a to heat the mixture of entrainment gas and brine.
The condensate thereby formed during the cooling of the water vapor -is decompressed in the decompression valve 65 and combined with the condensate coming from the heat exchanger 16a.
The brine collected in the separator 56 is extracted by the brine pump 57 and pumped at a pressure of PS = 6 bar to the heat exchanger 55. The brine evaporates there at an evaporation tempera-ture of TS = 167.5C to a residual amount of ~S = 1,424 kg/h. The ; :

; ~

~ NHL-KFJ-33 C~NADA
2C~

water vapor formed during evaporation of the brine is removed from the separator 56a at a temperature TD = 167.5C and flows with a ~--water quantity of ~D = 3,878 kg/h to the heat exchanger 16a. The heater 46a in this embodiment is usually not in operation, and is usually used only as an apparatus for the production of water vapor when the system is started up. In the heat exchanger 16a, the water vapor is again condensed, giving up heat to the sea water to be ;
partly evaporated, at a condensation temperature TC = 158.8C.
Together with the o~her quantity of condensate from the heat exchanger 55 and the evaporator 31a, the condensate in a quantity of ~C = 8,825 kg/h, and after combining and decompressing the condens~te from heat exchanger 55 and evaporator 31a at a condensa-tion temperature TC = 158.8C, flows on the heat transfer medium side through the heat exchanger 12a. The condensate flows out of ~-the heat exchanger 12a at a temperature of T = 30C.
With the valve 25a closed, the concentrated brine extracted --from the separator 20a is transported completely on the heat transfer medium side through the heat exchanger 4a, is decompressed ~ ;
at an initial temperature of TS = 100C by the valve 26 from PS = 6 bar to PS = 1 bar and then introduced by the brine pump 28a at a pressure of PS = 8 bar into the entrainment gas current. Ahead of the pump 28a, salt is again injected into the brine as seed. A
salt quantity ~Salz = 200 kg/h is added at a temperature of TSalz = ~ ~
190C. ~`
The entrainment gas current has a total pressure of Pt =
6.37 bar, which means that for the brine introduced into the entrainment gas current, there is a boiling temperature of TS
152.5C. In the evaporator 31a, the mixture of entrainment gas and ~.
water vapor formed by the evaporating brine is superheated to a temperature of TGD = 190C, so that salts dissolved in the sea water are precipitated as solid particles, which are separated from NHL-KFJ-33 C~NADA
2~

the mixture of entrainment gas and water vapor in the separator 34a. The mixture of entrainment gas and water vapor purified of the solid particles is pumped by the feed blower 36a to the heat exchanger 14a, whereby the pressure in the mixture of entrainment -~
gas and water vapor of PGD = 6.37 bar on the suction side of the feed blower is increased to PGD = 7.12 bar on the pressure side of the feed blower. The mixture of entrainment gas and water vapor behind the feed blower has a temperature TGD = 206C and consists of ~D = 1,018 kg/h of vapor and mL = 408 kg/h of air.
The water vapor in the mixture of entrainment gas and water vapor condenses in the heat exchanger 14a at a temperature TC = ~ -156.8C and is cooled with the entrainment gas, giving up heat to the sea water to be preheated in the heat exchanger 14a, to an initial temperature of TC = 80C. From the output of the heat exchanger 14a, the following flows exit: air as the entrainment gas in a quantity of ~L = 408 kg/h, a condensate quantity of ~C =
1,000 kg/h and a small amount of water vapor ~D = 18 kg/h. Before being returned to the entrainment gas circuit, the pressure of the mixture of entrainment gas and water vapor is reduced from PGD =
7.12 bar by the throttle 41a to PGD = 6.37 bar. At this pressure and at a temperature of TGD = 80C, brine is again sprayed into the -entrainment gas current.
The operation of the apparatus illustrated in Figure 7 ;
thereby differs from the operation of the systems illustrated in Figures 5 and 6 not only in the two-stage brine extraction and the separation of the water vapor formed in these stages, but also in an increased pressure level in the entrainment gas circuit. A
higher compression energy than in the entrainment gas circuit, however, is necessary for the compression of the water vapor in the compressor 60, which must raise the water vapor, instead of from PD
= 5 bar to PD = 7.1 bar in the embodiments illustrated in Figures 5 NHL-KFJ-33 C~N~D~
2 ~

and 6, from PD = 5 bar to PD = 8.4 bar in the embodiment illustrated in Figure 7. The increase of the pump power at this point, however, leads to a more favorable energy feed, so that overall, the cost per kg of purified water and salt produced can be reduced. ~ -~
In summation one embodiment of the invention resides broadly in a process to purify water and recover substances dissolved in ~ ;
the water by the introduction of the finely divided water contain~
ing the dissolved substances into an inert entrainment gas current, setting a specified partial pressure for the entrainment gas in the mixture of entrainment gas and water vapor which is formed by heating the mixture of entrainment gas and water until the water evaporates and superheating the water vapor produced, with the subsequent separation of the solid particles contained in the ~
mixture of entrainment gas and water vapor, the extraction of the ~ .
purified mixture of entrainment gas and water vapor and the cooling of the mixture to the condensation of the water vapor in the mixture of entrainment gas and water vapor, with the heat being given up to the medium to be heated during the performance of the process, characterized in that the water to be purified is first partly evaporated by adding heat, and that the brine formed by the partial evaporation is finely divided and introduced into the :
entrainment gas current, that the water vapor formed by the partial - ;
evaporation, after separation of the brine, is at least partly compressed, and gives up its heat on the one hand to heat the ~.
entrainment gas current after the addition of the brine to regulate .
the mixture of entrainment gas and water vapor which is free of droplets of water, and on the other hand for the partial evaporation of the water to be purified, and that the purified mixture of entrainment gas and water vapor is cooled, the water vapor contained in it is condensed, and it gives up its heat to preheat the water ~:

2~Q~ NHL-KFJ-33 C~N~

to be purified.
. .
Another embodiment of the invention resides broadly in a -process characterized in that the partial evaporation takes place ---~
at least for a portion of the water to be purified in several heat exchanger stages.
Yet another embodiment of the invention resides broadly in a process characterized in that only a portion of the water to be purified is preheated by the mixture of entrainment gas and water ~ ~`
vapor, and that the other portion is preheated by compressed water vapor, utilizing residual heat.
~ . .' ~ !
A further embodiment of the invention resides broadly in a process characterized in that the water to be purified is preheated in the heat exchange with the brine, before the brine is introduced into the entrainment gas.
A yet further embodiment of the invention resides broadly in a process characterized in that the water to be purified is pre-heated by condensate separated from the mixture of entrainment gas -and water vapor.
Yet another further embodiment of the invention resides broadly in a process characterized in that salts are added to the -water to be purified before its partial evaporation, which cor~
respond to the type of encrustation substances contained in the water, and that the salts are added in an amount which produces a supersaturation of the water, in particular a 10 - 30% supersatura~
tion for the salts added, and that the salts are isolated after the partial evaporation of the brine produced.
An additional embodiment of the invention resides broadly in a process characterized in that a portion of the salts, isolated from the water before its partial evaporation, are added once again.
A yet additional embodiment of the invention resides broadly 2~Q~3~ NHL-KFJ-33 ('~N~

in a process characterized in that the water contains abrasive substances during its partial evaporation.
A further additional embodiment of the invention resides broadly in a process characterized in that salt germs are added for salt formation in the brine obtained from the partial evaporation, in particular up to 10 - 30% supersaturation of the brine. ; - -A yet further additional embodiment of the invention resides broadly in a process characterized in that the salt germs are added before the entry of the brine into a brine pump which transports the brine.
Another further additional embodiment of the invention resides broadly in a process characterized in that during the partial evaporation of the water to be purified in several heat exchanger stages, the vapor formed in the final and penultimate heat exchanger stages is extracted.
A yet another additional embodiment of the invention resides broadly in a process characterized in that the brine in the final heat exchanger stage is heated with water vapor formed in the penultimate heat exchanger stage.
Another yet further embodiment of the invention resides broadly in a process characterized in that water vapor formed in the final heat exchanger stage is used to heat a preceding heat ~;
exchanger stage.
A still further embodiment of the invention resides broadly ;-in a process characterized in that water vapor flowing out of the penultimate heat exchanger stage is used at the same pressure as the heating medium and flows through the final heat exchanger stage, and that the brine obtained in the penultimate heat exchanger stage is decompressed before entering the final heat exchanger stage.
Another still further additional embodiment of the invention ;

33 ~

:-2~ 3~ NHL-KFJ-33 (:~N~

resides broadly in a process characterized in that the water vapor :
formed in the heat exchanger stages is combined at least in part with water vapor to be compressed before its compression.
Yet another still further additional embodiment of the invention resides broadly in a process characterized in that the condensate formed during the partial evaporation of the contaminated water in the heat exchangers and during the evaporation of the brine in the evaporator is combined and extracted jointly.
Still another yet further additional embodiment of the invention resides broadly in an apparatus for the performance of the process disclosed in one of the preceding claims to purify water and recover substances dissolved or suspended in the water to be purified, with an apparatus located on the input of a evaporator for the fine division of the water to be purified into an entrain-ment gas current, and with a salt separator at the output of the :
evaporator for solid particles which can be formed in the evaporator by superheating the mixture of entrainment gas and water vapor produced, and with a heat exchanger connected downstream of the salt separator, which is flowed through on the condensate side by purified entrainment gas/water vapor mixture for cooling to below :~
the condensation temperature of the water vapor, characterized in that the apparatus 32 to finely divide the water to be purified is preceded by at least one heat exchanger 16 operated with heated ~:~
water vapor to produce brine by partial evaporation of the water to~:
be purified, whereby the apparatus 32 for the fine division is ;.::~
connected to a brine discharge 23 of a separator 20 downstream of :~
the heat exchanger 16 for brine production, and the water vapor discharge 42 of the separator 20 is connected on one hand with a compressor 43 ior the water vapor, whose water vapor line 45 to an evapora~or 31 for the mixture of entrainment gas and brine, and on the other hand to a heat exchanger 16 for the partial evaporation NHL-KFJ-33 cl~NA~
2~Q 3 of the water to be purified, and that the hea~ exchanger 14 down- ~ -stream of the salt separator 34 is connected on the evaporation side with a feed 1 for the water to be purified, before its entry into the heat exchanger 16 for brine production. -~
Another still further yet additional embodiment of the invention is characterized in that several heat exchangers 12, 16; -~
12a, 16a, 55; 12b, 16b, 55b; 12c, 16c, 55c are connected in series ~
for the partial evaporation of the water to be purified. ~ -Another embodiment of the invention is characterized in that the heat exchanger 14 through which the purified mixture of entrain-ment gas and water vapor flows is connected in parallel with a heat exchanger 12 for the water to be purified, and the condensate from -the compressed water vapor flows on the heat transfer medium side through the heat exchanger 12.
Yet another embodiment of the invention is characterized in that one of the heat exchangers 4 for the water to be purified is -~
connected on the heat transfer medium side with the brine discharge .
23 of the separator 20 before the entry to the apparatus 32 for its fine division.
A further embodiment of the invention is characterized in that one of the heat exchangers 3 for the water to be purified is flowed through on the heat transfer medium side by the condensate of the water vapor from the mixture of entrainment gas and water vapor.
A yet further embodiment of the invention is characterized in that ahead of one of the heat exchangers 16 for the partial evaporation of the water to be purified, a brine line empties into ~ -~
the water current for salts which correspond to the type of en- ~-crustation substances contained in the water, and that downstream of the heat exchanger 16 there is a separator 20 for the salts added.

'`''-,;

' NHL KFJ-33 c~N~
- 2C~q~Q~3C) Yet another further embodiment of the invention is character~
ized in that connected to the separator 20 for the separated salt, there is a return line 22, which empties upstream of the heat exchanger 16 into a collecting main 15 which carries the water to be purified.
An additional embodiment of the invention is characterized in that upstream of the heat exchanger 16 for the brine production, a line carrying an abrasive substance empties into the collecting main 15, that the heat exchanger 16 is followed by a separator 20 for the abrasive substances, and that a return line 22 from the separator 20 empties into the collecting main 15 carrying the water `
to be purified. ;
A yet additional embodiment of the invention is charac~
terized in that a salt germ feed 54 empties into the brine feed line 29 to the evaporator 31.
A further additional embodiment of the invention is charac-terized in that the salt germ feed 54 is connected to the intake side of a brine pump 28.
A yet further additional embodiment of the invention is characterized in that the final heat exchanger 55 for the partial evaporation of the water to be purified is connected on the heat transfer medium side to the water vapor discharge 61 of the separator 56 of the penultimate heat exchanger 16a for the partial evaporation of the contaminated water.
Another further additional embodiment of the invention is characterized in that the water vapor line 44 of the separator 20a downstream of the final heat exchanger 55 for the partial evaporation of the water to be purified is connected to the heat transfer medium side of one of the heat exchangers 16a preceding the final heat exchanger 55.
A yet another additional embodiment of the invention is 2 ~ ~Q~ 3 ~ NHL-KFJ-33 ('~N~

characterized in that a pressure relief valve 70 is installed in the brine line 58b of a separator 56b.
Another yet further embodiment of the invention is charac-terized in that the water vapor is extracted from each of the ~ ~-separators 56c, 20c downstream of the penultimate and final heat exchangers 16c, 55c by a compressor 60c, 75, and that the pres-surized water vapor line of the one compressor 60c is connected on ~ -the heat transfer medium side to the evaporator 31c for the mixture of entrainment gas and brine, and the water vapor line 44c of the other compressor 75 is connected on the heat transfer medium side to a heat exchanger 16c for the partial evaporation of the water to ~
be purified. -A still further embodiment of the invention is characterized in that there is a separate evaporator 46 for the production of -~
water vapor.
A still further additional embodiment of the invention is characterized in that all the lines carrying condensate are connected to a water line 40 which discharges all the condensate together.
All of the patents, patent applications, and publications recited herein are hereby incorporated by reference as if set forth ~-in their entirety herein.
The invention as described hereinabove in the context of a -preferred embodiment is not to be taken as limited to all of the provided details thereof, since modifications and variations there-of may be made without departing from the spirit and scope of the invention. ~ `

",'- ' ' ' ~'' :-

Claims

1. Process for purifying water and recovering sub-stances dissolved or suspended in the water, said process comprising the steps of:
heating the water to be purified and partially evap-orating this water to be purified and thereby producing a brine and water vapor;
dividing at least a portion of the brine formed by partial evaporation into at least one of: drops and droplets, and introducing the brine into an entrainment gas stream to form a mixture of brine and entrainment gas;
forming water vapor from the brine by evaporating the brine in the gas stream by heating the mixture of entrainment gas and brine until the water evaporates to form a mixture free of droplets of water;
separating solid particles contained in the mixture of entrained gas and water vapor;
compressing water vapor formed in at least one previous step at least partially;
extracting heat from the compressing of the water vapor;
heating the entrainment gas stream, at a point after addition of the brine, with the heat extracted from the water vapor during compression of the water vapor;
condensing at least a portion of the water vapor contained in the mixture of entrainment gas and water vapor thereby producing purified water wherein heat is given off by the water vapor during condensation; and heating the water to be purified in the first above step with heat given off during condensation of the water vapor in the immediately above step.

2. The process according to Claim 1 including:
finely dividing the brine formed by partial evaporation for being mixed in the gas stream;
setting a specified partial pressure of the entrainment gases in the mixture of the entrainment gas and water vapor which is formed by heating the mixture of entrainment gas and water until the water evaporates;
heating the brine to regulate the mixture of entrain-ment gas and water vapor which mixture is free of droplets of water;
maintaining a specific partial pressure for the entrain-ment gas in the mixture of entrainment gas and water vapor;
superheating at least the water vapor produced by the heating of the mixture of entrainment gas and water;
the water vapor formed by the partial evaporation, after separation of the brine, is at least partly compressed;
and the water vapor gives up its heat on the one hand to heat the entrainment gas current after the addition of the brine to regulate the mixture of entrainment gas and water vapor which is free of droplets of water, and on the other hand for the partial evaporation of the water to be purified.

3. Process according to Claim 2, wherein the partial evaporation takes place at least for a portion of the water to be purified in several heat exchanger stages.

4. Process according to Claim 3, wherein only a portion of the water to be purified is preheated by the mixture of entrainment gas and water vapor, and that the other portion is preheated by compressed water vapor, utilizing residual heat.

5. Process according to Claim 4, wherein the water to be purified is preheated in the heat exchange with the brine, before the brine is introduced into the entrainment gas.

6. Process according to Claim 5, wherein the water to be purified is preheated by condensate separated from the mixture of entrainment gas and water vapor.

7. Process according to Claim 6, wherein salts are added to the water to be purified before its partial evap-oration, which correspond to the type of encrustation sub-stances contained in the water, and that the salts are added in an amount which produces a supersaturation of the water, in particular a 10 - 30% supersaturation for the salts added, and that the salts are isolated after the partial evaporation of the brine produced.

8. Process according to Claim 7, wherein a portion of the salts, isolated from the water before its partial evap-oration, are added once again.

9. Process according to Claim 8, wherein the water contains abrasive substances during its partial evaporation.

10. Process according to Claim 9, wherein seeds are added for salt formation in the brine obtained from the partial evaporation, in particular up to 10 - 30% super-saturation of the brine.

11. Process according to Claim 10, wherein the salt seeds are added before the entry of the brine into a brine pump which transports the brine.

12. Process according to Claim 11, wherein during the partial evaporation of the water to be purified in several heat exchanger stages, the vapor formed in the final and penultimate heat exchanger stages is extracted.

13. Process according to Claim 12, wherein the brine in the final heat exchanger stage is heated with water vapor formed in the penultimate heat exchanger stage.

14. Process according to Claim 13, wherein water vapor formed in the final heat exchanger stage is used to heat a preceding heat exchanger stage.

15. Process according to Claim 14, wherein water vapor flowing out of the penultimate heat exchanger stage is used at the same pressure as the heating medium and flows through the final heat exchanger stage, and that the brine obtained in the penultimate heat exchanger stage is decompressed before entering the final heat exchanger stage.

16. Process according to Claim 15, wherein the water vapor formed in the heat exchanger stages is combined at least in part with water vapor to be compressed before its com-pression.

17. Process according to Claim 16, wherein the con-densate formed during the partial evaporation of the contam-inated water in the heat exchangers and during the evaporation of the brine in the evaporator is combined and extracted jointly.

18. Apparatus for purifying water and recovering substances dissolved or suspended in the water to be purified, said apparatus comprising:
means for introducing the water to be purified into the apparatus;
at least one heat exchanger means operatively connected to said inlet means;
means for at least partially vaporizing water preheated in said at least one preheater means and partially evaporating the water to be purified to produce brine and water vapor;
means connecting said at least one preheater means and said means for vaporizing;
means for separating the water vapor from a mixture of water vapor and brine generated by said vaporizing means;
means for operatively connecting said means for vapor separation and said means for vaporizing;
compressor means for compressing vapor separated by said means for separating vapor;

means for connecting said compressor means to said means for separating vapor and for leading vapor separated by said vapor separator means to said compressor means;
means connected to said compressor means for conducting water vapor from said compressor means to at least one of said at least one heat exchanger means;
brine divider means for dividing said brine into at least one of: drops and droplets, and for introducing said brine into an entrainment gas stream;
means connecting said brine divider means with said separating means to deliver the brine to the brine divider means;
evaporator means for evaporating said brine;
means connecting said brine divider means with said evaporation means to deliver the brine to the evaporation means;
separator means for separating solid matter from said evaporated brine; and means connecting said brine divider means with said separator means to deliver the brine to said separator means.

19. Apparatus to purify water and recover substances dissolved or suspended in the water to be purified, with an apparatus located on the input of a evaporator for the fine division of the water to be purified into an entrainment gas current, and with a salt separator at the output of the evaporator for solid particles which can be formed in the evaporator by superheating the mixture of entrainment gas and water vapor produced, and with a heat exchanger connected downstream of the salt separator, which is flowed through on the condensate side by purified entrainment gas/water vapor mixture for cooling to below the condensation temperature of the water vapor, wherein the apparatus to finely divide the water to be purified is preceded by at least one heat ex-changer operated with heated water vapor to produce brine by partial evaporation of the water to be purified, whereby the apparatus for the fine division is connected to a brine discharge of a separator downstream of the heat exchanger for brine production, and the water vapor discharge of the sep-arator is connected on one hand with a compressor for the water vapor, whose water vapor line to an evaporator for the mixture of entrainment gas and brine, and on the other hand to a heat exchanger for the partial evaporation of the water to be purified, and that the heat exchanger downstream of the salt separator is connected on the evaporation side with a feed for the water to be purified, before its entry into the heat exchanger for brine production.

20. Apparatus according to Claim 19, wherein several heat exchangers are connected in series for the partial evaporation of the water to be purified.

21. Apparatus according to Claim 20, wherein the heat exchanger through which the purified mixture of entrainment gas and water vapor flows is connected in parallel with a heat exchanger for the water to be purified, and the condensate from the compressed water vapor flows on the heat transfer medium side through the heat exchanger.

22. Apparatus according to Claim 21, wherein one of the heat exchangers for the water to be purified is connected on the heat transfer medium side with the brine discharge of the separator before the entry to the apparatus for its fine division.

23. Apparatus according to Claim 22, wherein one of the heat exchangers for the water to be purified is flowed through on the heat transfer medium side by the condensate of the water vapor from the mixture of entrainment gas and water vapor.

24. Apparatus according to Claim 23, wherein ahead of one of the heat exchangers for the partial evaporation of the water to be purified, a brine line empties into the water current for salts which correspond to the type of encrustation substances contained in the water, and that downstream of the heat exchanger there is a separator for the salts added.

25. Apparatus according to Claim 24, wherein connected to the separator for the separated salt, there is a return line, which empties upstream of the heat exchanger into a collecting main which carries the water to be purified.

26. Apparatus according to Claim 25, wherein upstream of the heat exchanger for the brine production, a line car-rying an abrasive substance empties into the collecting main, that the heat exchanger is followed by a separator for the abrasive substances, and that a return line from the separator empties into the collecting main carrying the water to be purified.

27. Apparatus according to Claim 26, wherein a salt seed feed empties into the brine feed line to the evaporator.

28. Apparatus according to Claim 27, wherein the salt seed feed is connected to the intake side of a brine pump.

29. Apparatus according to Claim 28, wherein the final heat exchanger for the partial evaporation of the water to be purified is connected on the heat transfer medium side to the water vapor discharge of the separator of the penultimate heat exchanger for the partial evaporation of the contaminated water.

30. Apparatus according to Claim 29, wherein the water vapor line of the separator downstream of the final heat exchanger for the partial evaporation of the water to be purified is connected to the heat transfer medium side of one of the heat exchangers preceding the final heat exchanger.

31. Apparatus according to Claim 30, wherein a pres-sure relief valve is installed in the brine line of a sep-arator.

32. Apparatus according to Claim 31, wherein the water vapor is extracted from each of the separators downstream of the penultimate and final heat exchangers by a compressor and that the pressurized water vapor line of the one compressor is connected on the heat transfer medium side to the evaporator for the mixture of entrainment gas and brine, and the water vapor line of the other compressor is connected on the heat transfer medium side to a heat exchanger for the partial evaporation of the water to be purified.

33. Apparatus according to Claim 32, wherein there is a separate evaporator for the production of water vapor.

34. Apparatus according to Claim 33, wherein all the lines carrying condensate are connected to a water line which discharges all the condensate together.