Vacuum evaporation unit

Abstract

The invention relates to a vacuum evaporation unit (10) comprising:-a vacuum chamber (11) for containing a liquid solution (SL) to be treated, which in turn comprises a lower part (12) for collecting the liquid solution and an upper part (13) for generating rising vapours (V) from said liquid solution; a condensation chamber (14) in which condensation of the vapour (V) resulting from boiling of the liquid solution (SL) takes place; -heat exchange means (15) configured to generate a heat exchange between the vapour (V) of the liquid solution (SL) and the liquid solution (SL) itself; -first conveying means (16) configured to guide said vapour (V) from said upper portion (13) of said vacuum chamber (11) to said heat exchange means (15). The unit comprises a scrubbing tower (20) configured for countercurrent treatment of the vapour (V) exiting the vacuum chamber (11) with a liquid absorption solution (SA).

Description

Technical Field

[0001] The invention relates to a vacuum evaporation unit.

[0002] So called 'vacuum evaporators' are now well known and common in the disposal of contaminated liquid waste.

[0003] Vacuum evaporators are used to concentrate aqueous solutions containing contaminants by evaporating the water at low temperatures.

[0004] By treating the wastewater to be treated with a vacuum evaporator, the volume of wastewater to be treated is significantly reduced, allowing the recovered distilled water to be reused and returned to the source user.

[0005] Typically, vacuum evaporators make it possible to fully recirculate the water used in the production process, resulting in a drastic reduction in the amount of wastewater to be sent for treatment, reducing treatment costs and saving water supply.

[0006] In some cases, such as wastewater from electroplating bath washing and recycling, the concentrated recovery solution can be reused in the treatment bath.

[0007] The distillate obtained by vacuum evaporation is often contaminated with so-called "low-boiling" substances which remain in the vapor and lead to a deterioration in the quality of the distillate itself, making its use or discharge into sewage systems problematic, leading to the need for chemical-physical or biological post-treatments which are generally expensive in terms of investment and operating costs.

[0008] An evaporator is a machine that utilizes mechanical vapor compression.

[0009] For example, a vacuum evaporator may include an evaporation bowl, ie, a tank, which is configured to contain a liquid solution to be treated at a specific temperature and a predetermined pressure to reduce its evaporation temperature.

[0010] The liquid solution to be treated and the vapor of the same solution are separated in the evaporation bowl and crossed in the heat exchanger thanks to the forced circulation imposed by the corresponding pumping and compression means.

[0011] The evaporated liquid, i.e. the substance to be filtered and cleaned, is present in the evaporation bowl.

[0012] Vapor from the liquid solution is drawn in via a circulation pump and pushed toward a heat exchanger, such as a shell and tube heat exchanger.

[0013] The liquid solution circulates within the tubes of the heat exchanger, pushed by a circulating pump which draws the liquid solution out of the bottom of the evaporation bowl.

[0014] The outside of the heat exchanger tubes are overlapped by vapor from the liquid solution, which is sucked in by the compressor which pushes the liquid solution into the heat exchange chamber where the heat exchanger is located.

[0015] The liquid solution passes through the heat exchanger and is heated, leaving the heat exchanger as a superheated liquid back into the evaporation bowl.

[0016] Once in the evaporation bowl, the superheated liquid solution releases vapor again, thereby producing so-called "flash" evaporation, ie partial evaporation of the liquid solution.

[0017] In the heat exchange chamber, the vapor condenses outside the heat exchanger and releases energy to the solution circulating inside the heat exchanger.

[0018] The condensate or distillate formed outside the heat exchanger collects at the bottom of the heat exchange chamber and is drawn off there, for example, using a vacuum pump.

[0019] The condensate or distillate may be used as a source user of a source of liquid solution.

[0020] Due to such a vacuum evaporator, for example, 100 cubic meters of oily emulsion solutions, such as water-based release emulsions, are reduced by a factor of 10, ie they are reduced to 10 cubic meters, and the recovered distilled water is reused for the preparation of other release agents.

[0021] As mentioned above, the wastewater to be treated may contain pollutants, such as nitrogen in the form of ammoniacal nitrogen.

[0022] These low-boiling substances are distilled, i.e. evaporated, together with the vapor formed in the evaporator.

[0023] As mentioned above, low boiling point substances are gases that travel with the vapor and are then found in the condensate of the same vapor.

[0024] Low boiling point substances are water soluble gases.

[0025] On the other hand, substances that are insoluble in water, such as CO2 or nitrogen, are degassed in the vacuum pump and are called 'non-condensables' in technical terms.

[0026] These known vacuum evaporators, despite their widespread and popular use today, all suffer from the major problem of managing low boiling point substances.

[0027] The object of the present invention is to develop a vacuum evaporation unit which overcomes the above-mentioned disadvantages and limitations of the prior art.

[0028] In particular, it is an object of the present invention to develop a vacuum evaporation unit which is able to decompose low-boiling point pollutants from the gas phase.

[0029] Another object of the present invention is to develop vacuum evaporation units capable of recovering low-boiling substances so that they can be reused.

[0030] Another object of the invention is to develop a vacuum evaporation unit which can be combined with any existing type of vacuum evaporator.

[0031] This object and the aforementioned purpose are achieved by a vacuum evaporation unit according to claim 1 .

[0032] Further features of the evaporation unit according to claim 1 are described in the dependent claims.

[0033] The above tasks and objects as well as the advantages which will be mentioned below will be indicated by the description of an embodiment of the invention given by way of non-limiting example with reference to the accompanying drawings, in which:

[0034] - Figure 1 shows a schematic side view of a vacuum evaporation unit according to the present invention;

[0035] - Figure 2 represents a first part of an evaporation unit according to the invention;

[0036] - Figure 3 represents a second part of the evaporation unit according to the invention;

[0037] - Figure 4 A diagram showing a second part of an evaporation unit according to the invention;

[0038] - Figure 5 An embodiment of an evaporation unit according to the invention is shown.

[0039] With reference to the cited figures, a vacuum evaporation unit according to the invention is indicated as a whole by the reference numeral 10 .

[0040] The vacuum evaporation unit 10 comprises:

[0041] - a vacuum chamber 11 for containing the liquid solution SL to be treated; the vacuum chamber 11, which in industrial terminology is also called an 'evaporation bowl', comprises a lower part 12 for collecting the liquid solution and an upper part 13 for the rising vapor V generated from the liquid solution SL;

[0042] - heat exchange means 15 configured to determine a heat exchange between the vapor V of the liquid solution SL and the liquid solution SL itself;

[0043] - a condensation chamber 14 communicating with the heat exchange device 15, in which the vapor V is condensed by heat exchange with the liquid solution SL;

[0044] A first conveying device 16 configured to guide the vapour V from the upper part 13 of the vacuum chamber 11 towards the heat exchange device 15 .

[0045] As will be described in detail below with respect to two embodiments of the present invention, the vacuum chamber 11 and the heat exchange device 15 are operably connected to each other so that the liquid solution SL present in the lower part 12 of the vacuum chamber 11 contacts the aforementioned heat exchange device 15 so as to achieve such heat exchange between the vapor V of the liquid solution SL and the liquid solution SL itself. In addition, the vacuum chamber 11 and the heat exchange device 15 are operably connected to each other so that after the heat exchange, the liquid solution SL that has undergone such heat exchange is present in the aforementioned lower part 12.

[0046] The vacuum evaporation unit 10 according to the invention is characterized in that it comprises a washing tower 20 which belongs to said first conveying device 16 and is configured to treat the vapors V leaving the vacuum chamber 11 in countercurrent with a liquid absorption solution SA.

[0047] In an embodiment of the vacuum evaporation unit 10 according to the invention, described here by way of non-limiting example of the invention itself, the scrubbing column 20 comprises:

[0048] - an inlet port 21 for the vapor V exiting from the upper part 13 of the vacuum chamber 11;

[0049] - a settling tank 22 for collecting and settling the liquid absorption solution SA;

[0050] - an exchange column (or exchange tower) 23, which is configured for countercurrent exchange of substances between the ascending vapor V and the descending liquid absorption solution SA; the exchange column 23 is located above the settling tank 22;

[0051] - a distribution device 24, which is configured to diffusely distribute the liquid absorption solution SA above the exchange column 23;

[0052] - an outlet port 26 for the vapor V coming out of the scrubbing tower 20 .

[0053] The vapour V leaving the scrubber 20 is intended to be 'scrubbed' vapour, ie treated vapour, and is referred to as V1 for convenience to distinguish it from the untreated vapour V entering the scrubber 20 .

[0054] The washing tower 20 is connected to the upper part 13 of the vacuum chamber 11 at the inlet and is connected to the heat exchange device 15 at the outlet.

[0055] The inlet port 21 is connected to the upper part 13 of the vacuum chamber 11 by means of extraction and compression means 30 belonging to the first conveying means 16 .

[0056] For example, the extraction and compression device 30 comprises a centrifugal compressor which sucks the untreated vapor V from the upper part 13 and pushes it towards the inlet port 21 of the scrubbing tower 20 .

[0057] The first conveying device 16 thus comprises:

[0058] - Extraction and compression device 30;

[0059] a first duct 31 for the untreated vapour V, configured to connect the vapour outlet port 13a with the suction port of the extraction and compression device 30;

[0060] a second conduit 32 for the untreated vapour V, configured to connect the delivery port of the extraction and compression device 30 with the inlet port 21 of the scrubbing tower 20;

[0061] - a washing tower 20;

[0062] - a third conduit 33 for treated vapour V1 , configured to connect the outlet port 26 of the scrubber tower 20 with the inlet port 15a of the heat exchange device 15 , which is described in more detail below.

[0063] Specifically, in this embodiment example, the wash tower 20 comprises a droplet separator 27 placed above the distribution device 24 .

[0064] The droplet separator 27 is also known in the industry as a 'demister'.

[0065] In this embodiment example, the distribution device 24 comprises a set of blowers 24a.

[0066] The distribution device 24 includes a recirculation pump 34 configured to suck the absorption solution SA from the settling tank 22 and push it toward the blower 24a.

[0067] For example, if the vapor V entering the scrubber 20 contains contaminants including ammonium ions, the absorption solution SA is sulfuric acid.

[0068] This absorption solution SA is sprayed by the blower 24a onto the vapor V containing ammonium ions, reacts with the latter, and returns to the settling tank 22 below in the form of a solution containing ammonium sulfate;

[0069] Ammonium sulfate can be effectively used as a fertilizer.

[0070] The distribution device 24 also includes a pH meter 35 that is constructed and positioned to detect the acidity of the absorption solution SA that is taken out from the settling tank 22 to be sent to the blower 24a.

[0071] The dispensing device 24 also includes a filling pump 36 configured to inject substances for re-establishing the established pH level into the absorption solution SA; for example, the filling pump 36 pumps sulfuric acid into the scrubbing tower 20, which can be used to react with ammonium ions present in the vapor V entering the scrubbing tower 20.

[0072] The wash tower 20 may further comprise an auxiliary distribution device 28 configured to diffusely distribute the liquid wash and make-up solution SA1 above said droplet separator 27 .

[0073] In this embodiment example, the auxiliary distribution device 28 comprises a series of blowers 28a.

[0074] The auxiliary dispensing device 28 includes a tank 38 for the liquid washing and replenishing solution SA1 and an auxiliary recirculation pump 37 configured to suck the liquid washing and replenishing solution SA1 from the tank 38 and push it toward the blower 28a.

[0075] The exchange column 23 is a packing type column.

[0076] The exchange column 23 is filled with Raschig rings or other similar annular elements.

[0077] Raschig rings are cylinders made of ceramic, metal or plastic that are used to increase the surface area available for chemical reactions. They are usually shaped as a hollow cylinder with a diameter equal to the length of the cylinder.

[0078] Thus, the Raschig ring array provided in the exchange column 23 results in an increase in the surface area available for chemical reactions between the rising vapor V and the absorption solution SA distributed by the distribution device 24 and possibly between the vapor V and the liquid washing and makeup solution SA1 distributed by the auxiliary distribution device 28 (if present).

[0079] The washing tower 20 includes a holding tank which defines a settling tank 22, an exchange column 23, a blower 24a of a distribution device 24, a droplet separator 27, and a blower 28a of an auxiliary distribution device therein.

[0080] In this non-limiting embodiment of the invention, the vacuum evaporation unit 10 comprises a second conveying device 17 configured to guide the liquid solution SL from the lower portion 12 of the vacuum chamber 11 to the heat exchange device 15 .

[0081] In the embodiment of the invention described here by way of non-limiting example of the invention itself, the heat exchange device 15 comprises a tank 40 in which a heat exchanger 41 is arranged. The condensation chamber 14 is defined in the tank 40 around the heat exchanger 41 described above.

[0082] The heat exchanger 41 is connected to the second conveying device 17 at an inlet and to the upper part 13 of the vacuum chamber 11 at an outlet.

[0083] Specifically, the heat exchanger 41 is connected to a middle area of ​​the vacuum chamber 11 via an outlet conduit 53 above the liquid solution SL and below the vapor outlet port 13 a .

[0084] The tank 40 comprises an inlet port coinciding with the aforementioned inlet port 15a of the heat exchanger device 15 , connected to said outlet port 26 of said scrubber tower 20 , and at least one outlet port 43 connected to a discharge device 44 configured to extract condensate from the bottom of said tank 40 .

[0085] The exhaust device 44 may include, for example, a vacuum pump 45 connected to the exhaust port 43 via an exhaust pipe 46 .

[0086] As an example, the second conveying device 17 includes a circulation pump 50 which is connected to the bottom of the vacuum chamber 11 via a loading conduit 51 and to the inlet port 41 a of the heat exchanger 41 via a delivery conduit 52 .

[0087] The vacuum chamber 11 is understood to be connected to a vacuum generating device, which is of a type known per se and is not shown for the sake of simplicity.

[0088] The liquid solution SL enters the heat exchanger 41 from the inlet port 41 a at a certain temperature and leaves the heat exchanger 41 at a higher temperature from the outlet port 41 b connected to the middle area of ​​the vacuum chamber 11 via the outlet conduit 53 .

[0089] The liquid solution SL is heated in the heat exchanger 41 and returns to the vacuum chamber 11 at a temperature at which the low pressure in the vacuum chamber 11 causes flash evaporation, ie, partial evaporation.

[0090] The vapor V rises toward the port 13a, while the liquid portion falls back toward the lower portion 12 where the liquid solution SL is collected.

[0091] The vacuum chamber 11, also called the 'evaporation bowl', comprises:

[0092] A tank configured to contain a liquid solution SL to be treated at a certain temperature and a predetermined pressure such that its evaporation temperature is reduced.

[0093] The liquid solution SL to be treated and the vapor V of the same solution are separated in the evaporation bowl and pass through the heat exchanger 41 in the tank 40 , thanks to the first conveying means 16 which suck in and compress the vapor V, and to the forced circulation imposed by the second conveying means 17 which pump the liquid solution SL into the heat exchanger 41 .

[0094] The heat exchanger 41 is, for example, of the shell and tube type, but it may be of another type according to specific technical requirements.

[0095] The liquid solution SL is maintained at a predetermined level in the vacuum chamber 11 by means of a level sensor 11 a placed in the vacuum chamber 11 and by means of a top-up line, not shown, which feeds new liquid solution SL to be processed from an external tank into the loading conduit 51 .

[0096] The evaporated liquid is a vapor V which must be filtered and cleaned.

[0097] From the upper part 13 of the vacuum chamber 11 , the vapor V is sucked in by the extraction and compression device 30 and pushed toward the washing tower 20 .

[0098] For example, if the liquid solution is 60°C in the lower part 12 of the vacuum chamber 11, the same liquid solution is heated to 70°C in the heat exchanger 41 and when it returns to the vacuum chamber 11, the superheated liquid solution returns to 60°C, releasing vapor V.

[0099] The vapor V is sucked into the compressor, which compresses the vapor V and sends it to the scrubber 20 , and returns from the scrubber 20 to the heat exchange device 15 , that is, inside the tank 40 , so that the vapor V contacts the outer surface of the heat exchanger 41 .

[0100] The treated vapor V1 leaving the scrubber 20 condenses in the tank 40 and releases energy to the liquid solution SL circulating in the heat exchanger 41 .

[0101] The condensate or distillate, ie the vapor condensed in the tank 40, is extracted with a vacuum pump and collected for resupply to the user.

[0102] The second conveying device 17 may include an auxiliary heater, which is not shown in the figure for simplicity, and is placed at the delivery conduit 52 for heating the liquid solution SL before it enters the heat exchange device 15 .

[0103] Such an auxiliary heater, for example, is constituted by a resistive device that is configured to surround the delivery catheter 52 .

[0104] When the condensate or 'distillate' is discharged from the tank 40, it is at a temperature of about 60°C; for this purpose, the discharge device 44 may comprise a recovery exchanger passing the liquid solution entering the vacuum evaporation unit 10; the entering liquid solution SL heats up, while the condensate cools down.

[0105] The waste liquor solution treated by the unit 10 according to the present invention may be, for example but not limited to, a solution of an oil emulsion, or a solution of a water-based release agent, which may contain contaminants, such as nitrogen in the form of ammoniacal nitrogen.

[0106] The pressure inside the vacuum chamber 11 is about -0.8 bar.

[0107] All low-boiling substances are distilled, i.e. evaporated, together with the vapor formed in the evaporator.

[0108] As mentioned above, low boiling point substances are gases that leave with the vapor and are then found in the vapor condensate. Therefore, they are water soluble gases.

[0109] Substances known to be 'insoluble' in water, such as CO2 or nitrogen, are separated in the vacuum pump 45 of the discharge device 44 by which the condensate is extracted from the tank 40 and are also referred to as "non-condensables".

[0110] The vacuum pump 45 has a tank called an 'incondensable separator'; these incondensable gases are released to the atmosphere, whereas soluble gases, such as ammonium ions or other low boiling point substances, if they are not removed in the scrubber 20, recondense in the condensate.

[0111] The vapors often contain low boiling point contaminants which pass into the distillate.

[0112] Due to the scrubbing column 20, the vacuum evaporation unit 10 removes contaminants from the distillate so that the distillate can be used by consumers.

[0113] Due to the scrubber 20 and the particular absorption solution SA used, which is specific to the type of pollutants to be removed from the vapor V, the pollutants are concentrated within the absorption solution SA, which becomes a substance that can have practical applications.

[0114] For example, if the contaminants in the vapor V are ammonium ions, the absorption solution SA is an acid solution, such as sulfuric acid for the ammonium ions.

[0115] In this example, the final absorption solution collected in the settling tank 22 contains 30% ammonium sulfate and can be certified as a fertilizer.

[0116] The scrubber 20 operates in a closed circuit and does not scrub the air, but rather the vapor V.

[0117] Blowers 24a and 28a are atomizers / sprayers that spray the absorption solution SA, which then becomes enriched and becomes rich in pollutants; in the above example, the solution SA composed of sulfuric acid as a starting point combines with ammonium ions and becomes ammonium sulfate.

[0118] Ammonium sulfate falls back and is neutral, so in order to keep the pH of the absorption solution constant, new sulfuric acid is introduced into the absorption solution SA itself via the filling pump 36 so that the absorption solution SA can always absorb ammonium ions arriving with new vapor.

[0119] The treated vapor V1 is distilled without contaminants inside, or is at least purified of 90% of the contaminants.

[0120] The settling tank 22 comprises a discharge valve which discharges the absorption solution SA when the same settling tank 22 is full of neutralization solution and is no longer able to capture the pollutants present in the fresh vapor V entering the scrubber 20 .

[0121] The water output together with the discharged absorption solution SA is replenished with the new solution contained in the tank 38 .

[0122] If the vapor V contains a low-boiling-point solvent, the absorption solution SA contains solvent naphtha.

[0123] The vacuum evaporation unit 10 according to the invention allows the elimination of low-boiling point contaminants in the gas phase, while enabling the production of a concentrated solution that can be reused or delivered directly as residue, eliminating expensive post-treatment.

[0124] exist Figure 5 Schematically shown in FIG. 1 is a variant embodiment of a vacuum evaporation unit according to the present invention, which is referred to herein as 110 .

[0125] The vacuum evaporation unit 110 includes:

[0126] - a vacuum chamber 111 for containing the liquid solution SL to be treated, comprising a lower part 112 for collecting the liquid solution and an upper part 113 for the rising vapor generated from the liquid solution;

[0127] - a condensation chamber 114 in which condensation of the vapor produced by boiling of the liquid solution occurs;

[0128] - heat exchange means 115 configured to generate a heat exchange between said vapor V of said liquid solution SL and said liquid solution SL itself;

[0129] A first conveying device 116 configured to guide said vapour V from said upper part 113 of said vacuum chamber 111 towards said heat exchange device 115 .

[0130] In this variant embodiment, the heat exchange device 115 is located in the lower part 112 of the same vacuum chamber 111 , and the condensation chamber 114 is defined by the same heat exchange device 115 .

[0131] Specifically, the heat exchanger 141 is located within the lower portion 112 and is immersed in the liquid solution SL.

[0132] The first conveying device 116 comprises:

[0133] - Extraction and compression device 130;

[0134] a first duct 131 for untreated vapour V, configured to connect the vapour outlet port 113a to the suction port of the extraction and compression device 130;

[0135] a second conduit 132 for the untreated vapour V, configured to connect the delivery port of the extraction and compression device 130 with the inlet port 21 of the scrubbing tower 20;

[0136] - a washing tower 20;

[0137] a third conduit 133 for the treated vapour V1 , configured to connect the outlet port 26 of the scrubber tower 20 with the inlet port 115 a of the heat exchange device 115 .

[0138] Therefore, in this modified embodiment, the processed vapor V1 flows into the heat exchanger 141 instead of flowing to the outside as in the previous modified embodiment, and in the same heat exchanger 141, the processed vapor V1 is condensed due to heat exchange with the external liquid solution SL present in the lower part 112 and then discharged to the outside. Therefore, as described above, the condensation chamber 114 is defined by the heat exchanger 141 itself.

[0139] In practice, it has been determined that the present invention achieves the intended tasks and objects.

[0140] In particular, the present invention develops a vacuum evaporation unit capable of decomposing low boiling point pollutants from the gas phase.

[0141] Furthermore, the present invention develops vacuum evaporation units capable of recovering low-boiling point substances so that they can be reused.

[0142] Furthermore, the invention provides a vacuum evaporator unit which can be combined with any existing type of vacuum evaporator.

[0143] The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; moreover, all the details may be replaced by other technically equivalent elements.

[0144] In practice, the components and materials used, as long as they are compatible with the specific use, as well as the dimensions and possible shapes, may be any according to requirements and the state of the art.

[0145] If features and techniques mentioned in any of the claims are followed by reference numerals, these reference numerals are used only for the purpose of increasing the intelligibility of these claims and thus, these reference numerals have no limiting effect on the interpretation of each element identified by example from these reference numerals.

Claims

1. A vacuum evaporation unit (10, 110), configured for treating a contaminated liquid solution (SL), comprising: - a vacuum chamber (11, 111) for containing the contaminated liquid solution (SL) to be treated, said vacuum chamber in turn comprising a lower part (12) for collecting said liquid solution (SL) and an upper part (13, 113) for generating rising vapor (V) from said liquid solution, said vacuum chamber (11, 111) being connected to a vacuum generating device; - a heat exchange device (15, 115) configured for exchanging heat between the vapor (V) of the liquid solution (SL) and the liquid solution (SL) itself, the vacuum chamber (11, 111) and the heat exchange device (15, 115) being operatively connected so that the liquid solution (SL) present in the lower part (12, 112) of the vacuum chamber (11, 111) is in contact with the heat exchange device (15, 115); - a condensation chamber (14, 114) connected to the heat exchange device (15, 115), wherein the vapor (V) generated by boiling the liquid solution (SL) is condensed in the condensation chamber (14, 114) after heat exchange with the liquid solution (SL); - first conveying means (16, 116) configured to guide the vapor (V) from the upper portion (13, 113) of the vacuum chamber (11, 111) to the heat exchange device (15, 115), Characterized in that the first conveying device (16, 116) comprises: - a first duct (31, 131) for said vapour (V), said first duct (31, 131) being configured to connect a vapour outlet port (13a, 113a) defined in said upper part (13, 113) with a suction port of an extraction and compression device (30, 130); - said extraction and compression means (30, 130); - a second conduit (32, 132) for said vapour (V), said second conduit being configured to connect the delivery port of said extraction and compression device (30, 130) with the inlet port (21) of the scrubbing tower (20); - the scrubbing tower (20) being configured for treating the vapor (V) exiting from the vacuum chamber (11, 111) with a liquid absorption solution (SA) in countercurrent; a third conduit (33, 133) for the vapor (V1) treated with the scrubbing tower (20), the third conduit (33, 133) being configured to connect the outlet port (26) of the scrubbing tower (20) with the inlet port (15a, 115a) of the heat exchange device (15, 115), The washing tower (20) further comprises: - a settling tank (22) for collecting and settling the liquid absorption solution (SA); - an exchange column (23) of the packed type and configured for countercurrent exchange of substances between the ascending vapor (V) and the descending liquid absorption solution (SA), said exchange column (23) being located above the settling tank (22); - distribution means (24) configured to diffusely distribute the liquid absorption solution (SA) over the exchange column (23).

2. The vacuum evaporation unit according to claim 1, characterized in that: The wash tower (20) comprises a droplet separator (27) placed above the distribution device (24).

3. The vacuum evaporation unit according to one or more of the preceding claims, characterized in that The wash tower (20) comprises an auxiliary distribution device (28) configured to diffusely distribute the liquid wash and replenishing solution (SA1) above the droplet separator (27).

4. The vacuum evaporation unit according to the preceding claim, characterized in that The exchange column (23) is filled with Raschig rings or similar ring-shaped elements.

5. The vacuum evaporation unit according to one or more of the preceding claims, characterized in that It comprises second conveying means (17) configured to guide the liquid solution (SL) coming from the lower part (12) of the vacuum chamber (11) to the heat exchange device (15).

6. The vacuum evaporation unit according to claim 5, characterized in that The heat exchange device (15) comprises a tank (40) in which a heat exchanger (41) is arranged, the heat exchanger (41) being connected to the second conveying device (17) at an inlet and to the upper part (13) of the vacuum chamber (11) at an outlet, the tank (40) comprising an inlet port (42) connected to the outlet port (26) of the scrubbing tower (20), and at least one discharge port (43) connected to a discharge device (44), the discharge device (44) being configured to extract condensate from the bottom of the tank (40).

7. The vacuum evaporation unit according to claim 6, characterized in that: The heat exchanger (41) is connected to a middle area of ​​the vacuum chamber (11) above the liquid solution (SL) and below the vapor outlet port (13a) by means of an outlet conduit (53).

8. The vacuum evaporation unit according to any one of claims 6 or 7, characterized in that: The discharge device (44) comprises a vacuum pump (45) connected to the discharge port (43) by means of a discharge conduit (46).

9. The vacuum evaporation unit according to any one of claims 6 to 8, characterized in that The transfer device (17) comprises a circulation pump (50) connected to the bottom of the vacuum chamber (11) by means of a loading conduit (51) and to the inlet port (41a) of the heat exchanger (41) by means of a delivery conduit (52).

10. The vacuum evaporation unit according to any one of the preceding claims, characterized in that The dispensing device (24) comprises a filling pump (36) configured to introduce into the absorption solution (SA) a substance that contributes to re-establishing the pH level that has been established.

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