EP3321419B1

EP3321419B1 - Multi stage washing column and device for drying wetted material comprising a multi stage washing column

Info

Publication number: EP3321419B1
Application number: EP16197891.1A
Authority: EP
Inventors: Johannes Theodorus Gerardus Marie EURLINGS
Original assignee: RWE Generation NL BV
Current assignee: RWE Generation NL BV
Priority date: 2016-11-09
Filing date: 2016-11-09
Publication date: 2021-01-13
Anticipated expiration: 2036-11-09
Also published as: DK3321419T3; PL3321419T3; EP3321419A1

Description

The present invention relates to a use of a multi stage washing column. Moreover, the present invention relates to a device for drying wetted material comprising a multi stage washing column.
Wetted material pursuant to the present invention can be wetted paper from a paper mill. Nevertheless, the present invention is not restricted to wetted paper as wetted material. The wetted material also can be wetted malt, wetted food, or wetted paint. The present invention will be described in the following with regard to wetted paper as wetted material. Nevertheless, the multi stage washing column according to the use according to the present invention can be used in a device for drying wetted paper, wetted paint, wetted malt, wetted food, and so on. Thereby it is to be mentioned that the relevant temperatures for drying paper (60 °C - 150 °C) are at an elevated temperature level compared to the temperatures (10 °C to 70 °C) mentioned with regard to the process of drying wetted malt.
In the paper industry multiple steam fed cylinders and/or one big cylinder - a so called Yankee - are used as drying devices / drying chambers for drying paper from typically 47% dry mass (DM) up to 93% dry mass. According to the state of the art heat recovery is in place, recuperating the sensible heat in the moisturized drying air coming from the drying chambers.
The process of drying wetted paper is very energy consuming. It is therefore an issue to reduce the energy consumption required for drying wetted paper.
From JP H 09 38 441 a multi stage tower scrubber is known. Further, from GB 1216858 A a paper or paper pulp drying plant is known.
The object of the present invention is to provide a device for drying wetted material and a use of a washing column which can be used in a device for drying wetted material, wherein the washing column enables a more efficient heat energy recovery and exhibits less liquid (water) consumption for recovering the heat energy of gas exiting the device for drying wetted material.
This object is solved by a device and a use of a multi stage washing column exhibiting the features of independent claims 1 and 6. Advantageous embodiments are described in the dependent claims.
In detail, the invention is directed to the use of a multi stage washing column that comprises a gas inlet for introducing a gas into the multi stage washing column, a gas outlet for exiting the gas out of the multi stage washing column, a hot liquid inlet for introducing liquid into the multi stage washing column, a cold liquid inlet for introducing liquid into the multi stage washing column, and a liquid outlet for exiting the liquid out of the multi stage washing column, wherein in a mounting position of the multi stage washing column the cold liquid inlet is positioned above the hot liquid inlet.
In the mounting position of the multi stage washing column liquid introduced into cold liquid inlet follows the gravitational force into the direction to the hot liquid inlet.
In this description "fluidly connected" means in general that the described parts are directly connected or indirectly connected with other parts in between. In any case a fluid stream is possible between the described parts.
In this description "thermally connected" means in general that the described parts are directly connected or indirectly connected with other parts in between. In any case a transfer of thermal energy is possible between the described parts.
Gas in the meaning of the present invention can for example be humid air and/or a mixture of air and steam. Liquid in the meaning of the present invention can for example be water.
The multi stage washing column according to the use according to the present invention exhibits the advantage that the thermal energy of the gas introduced into the multi stage washing column can be more effectively extracted and therefore can be more effectively used by other devices (for example for heating of a drying device, for heating of water, for heating of a building and so on) which are fluidly and/or thermally connected with the multi stage washing column. Especially when the temperature of the gas introduced in the multi stage washing column exhibits a high temperature, for example in the range of 150°C, the thermal energy being the sum of sensible and latent heat of the gas can be extracted by the multi stage washing column very effectively.
Gas introduced into the multi stage washing column exhibits a dew point which depends on the temperature of the gas and the percentage of humidity of the gas which also can be named the moisture content of the gas. Liquid exhibiting a temperature slightly below the dew point of the gas introduced into the multi stage washing column can be introduced into the multi stage washing column via the hot liquid inlet. Since the humidity absorption capacity of gas and air, respectively, rises exponentially with the temperature of the gas/air, a very high percentage of the humidity of the gas/air condensates when the gas/air is cooled down by the liquid introduced into the multi stage washing column via the hot liquid inlet. The liquid introduced into the multi stage washing column via the hot liquid inlet is heated by the condensation of the humidity of the gas/air and by heat transfer from the gas/air to the liquid. For that reason the temperature of the liquid collected at a bottom of the multi stage washing column is considerably high and therefore the heat energy of the liquid can be very effectively used by other devices (e.g. a heat pump). The gas ascending inside the multi stage washing column exhibits a reduced temperature, a reduced humidity and therefore a reduced dew point. Liquid exhibiting a temperature slightly below the reduced dew point of the gas ascended in the multi stage washing column can be introduced into the multi stage washing column via the cold liquid inlet. Compared to the amount of liquid introduced into the washing column via the hot liquid inlet a reduced amount of liquid is introduced into the multi stage washing column via the cold liquid inlet. This reduced amount of liquid is sufficient to condensate out a further percentage of humidity out of the gas/air. Therefore, the liquid introduced into the multi stage washing column via the cold liquid inlet only slightly cools down the liquid collected at the bottom of the multi stage washing column.
Consequently, the thermal energy of the gas/air introduced into the multi stage washing column can be extracted wherein at the same time the temperature of the liquid collected inside the multi stage washing column at its bottom is only slightly below the dew point of the gas introduced into the multi stage washing column. Therefore, the thermal energy of the gas is transferable to other devices very effectively.
A correspondingly designed multi stage washing column can be named a 2-stage washing column.
The humidity absorption capacity of the gas/air can also be named water vapor capacity of the gas/air.
The multi stage washing column also can be named a multi stage heat recovery washing column.
The hot liquid inlet can also be named a washing column hot liquid inlet or a first liquid inlet or a first washing column liquid inlet or a hot water inlet.
The cold liquid inlet can also be named a washing column cold liquid inlet or a third liquid inlet or a third washing column liquid inlet or a cold water inlet.
The liquid outlet can also be named a washing column liquid outlet or a water outlet or a washing column water outlet. In the mounting position of the multi stage washing column the liquid outlet is positioned underneath the hot liquid inlet.
The hot liquid inlet is adapted for introducing a liquid (preferably water) of a first temperature into the washing column. The first temperature can preferably be in the range of 65°C to 75°C.
The cold liquid inlet is adapted for introducing a liquid (preferably water) of a third temperature into the washing column. The third temperature is lower than the first temperature. The third temperature can preferably in the range of 10°C to 55°C. Consequently, a temperature of the liquid introduced into the washing column via the hot liquid inlet has to be higher than a temperature of the liquid introduced into the washing column via the cold liquid inlet so that the multi stage washing column can function in its designated manner.
The gas introduced into the multi stage washing column and exiting the multi stage washing column can be a mixture of air (breathing air) and moisture, wherein the gas exiting the multi stage washing column exhibits a lower percentage of absorbed humidity/water.
In the mounting position of the multi stage washing column the gas outlet is positioned above the cold liquid inlet which is positioned above the hot liquid inlet which is positioned above the gas inlet. Preferably, the liquid outlet is positioned underneath the gas inlet.
The multi stage washing column preferably is designed in that way that in the mounting position of the multi stage washing column the gas outlet is positioned above the gas inlet.
The multi stage washing column further comprises an intermediate temperature liquid inlet, wherein the intermediate temperature liquid inlet is positioned between the hot liquid inlet and the cold liquid inlet.
The correspondingly designed multi stage washing column exhibits the advantage that thermal energy of hot gas (e.g. a mixture of hot air and steam) introduced into the multi stage washing column via the gas inlet can be even more effectively extracted, wherein the liquid/water collected at the bottom of the multi stage washing column exhibits a higher temperature, and wherein the overall liquid consumption required for cooling down the gas and for drying the gas is reduced. Since the liquid collected at the bottom of the multi stage washing column exhibits a higher temperature, the thermal energy of the liquid can be more effectively transferred to another device (for example a transfer via a heat pump). A correspondingly designed multi stage washing column can be named a 3-stage washing column.
Preferably, the multi stage washing column comprises a plurality of liquid inlets, wherein in the mounting position of the multi stage washing column each liquid inlet is arranged at a different vertical position of the multi stage washing column.
The multi stage washing column can exhibit four, five, six, or even more liquid inlets. The number of liquid inlets, which is identical with the number of stages of the multi stage washing column, is a function of the dew point of the incoming venting gas.
A liquid inlet of the multi stage washing column is adapted for introducing a liquid exhibiting a temperature which is lower than a temperature of liquid introduced into the multi stage washing column via a liquid inlet which is positioned vertically underneath said liquid inlet. Therefore, the temperature of liquid introduced into the multi stage washing column via the plurality of liquid inlets decreases with higher positioning of the liquid inlets.
The object of the present invention is also solved by a device for drying wetted material which comprises at least one drying device for accommodating the wetted material, an above described multi stage washing column, and a heat pump, wherein the liquid outlet of the multi stage washing column is fluidly connected with a first heat pump liquid inlet and a first liquid outlet of the heat pump is fluidly connected with the hot liquid inlet of the multi stage washing column. A second heat pump inlet is fluidly connected with a with a hot fluid source, and a second heat pump outlet is fluidly connected with a drying device gas inlet and a drying device outlet is fluidly connected with the gas inlet of the multi stage washing column.
Due to the fluid connection of the multi stage washing column with the heat pump a heat cycle between the washing column and the heat pump is realized. The heat cycle is realized between the liquid outlet of the multi stage washing column, the first heat pump liquid inlet, the first heat pump liquid outlet, and the hot liquid inlet of the multi stage washing column. Thermal energy extracted from the water exiting the multi stage washing column is transferred to the heat pump and thermal energy extracted from the heat pump is transferred to the medium entering the heat pump via the second heat pump inlet, so that the medium exiting the heat pump via the second heat pump outlet can be used for drying the wetted material.
The wetted material preferably is wetted paper.
The drying device can comprise a drying chamber and/or can be named a drying chamber and/or can be named a Yankee. Moreover, the drying device can comprise a plurality of drying chambers and/or multiple drying cylinders.
The hot gas introduced into the drying device via the drying device gas inlet usually is hot air and/or a mixture of hot air and moisture.
The first heat pump liquid inlet can also be named a first heat pump water inlet. The first heat pump liquid outlet can also be named a first heat pump water outlet. The second heat pump liquid inlet can also be named a second heat pump water inlet. The second heat pump liquid outlet can also be named a second heat pump water outlet or second heat pump steam outlet.
For example the hot fluid source can be a boiler for feeding hot water and/or hot steam and/or hot air. The water/steam/air can preferably exhibit a temperature of more than 105°C.
The gas/steam exiting the heat pump via the second heat pump outlet preferably exhibits a pressure of three to four bar.
More preferably, the device for drying wetted material further comprises a compressor arranged between the second heat pump outlet and the drying device gas inlet, wherein a compressor inlet is fluidly connected with the second heat pump outlet and a compressor outlet is fluidly connected with the drying device gas inlet.
By fluidly connecting the compressor with the second heat pump outlet the pressure of the gas/air/steam exiting the heat pump via the second heat pump outlet can be increased from approximately 3 to 4 bar up to approximately 8 to 9 bar which is more suitable for drying device which can be realized as heating cylinders.
Preferably, the compressor is designed as a steam compressor.
More preferably, the device comprises the above described 3-stage washing column exhibiting the intermediate temperature liquid inlet. The device further comprises a heat exchanger, wherein a first heat exchanger liquid inlet is fluidly connected with the first heat pump liquid outlet and the hot liquid inlet of the multi stage washing column. A first heat exchanger liquid outlet is fluidly connected with the intermediate temperature liquid inlet of the multi stage washing column, and a second heat exchanger liquid inlet and a second heat exchanger liquid outlet are fluidly connected with a heat energy consumer, so that thermal energy from the liquid introduced into the heat exchanger via the first heat exchanger liquid inlet is transferable to the heat energy consumer.
The heat energy consumer can be for example a process water tank and/or a space heating. The heat exchanger can also be named a heat pump and a second heat pump, respectively.
Due to the fluid connection of the multi stage washing column with the heat exchanger a heat cycle between the washing column and the heat exchanger is realized. The heat cycle is realized between the liquid outlet of the multi stage washing column, the first heat pump liquid inlet, the first heat pump liquid outlet, the first heat exchanger liquid inlet, the first heat exchanger outlet and the intermediate temperature liquid inlet of the multi stage washing column. Thermal energy extracted from the water exiting the heat pump via the first heat pump liquid outlet is transferred to the heat exchanger and thermal energy extracted from the heat exchanger is transferred to a medium (for example water) circulating between the heat energy consumer (for example a process water tank and/or a space heating) and the heat exchanger via the second heat exchanger inlet and the second heat exchanger outlet.
A valve / flow adjuster can be arranged directly upstream of the first heat exchanger liquid inlet and/or upstream of the intermediate temperature liquid inlet of the multi stage washing column, so that a distribution of the amount of fluid flowing into the heat exchanger and flowing into the multi stage washing column via the intermediate temperature liquid inlet is adjustable.
More preferably, the device for drying wetted material is designed that way that the cold liquid inlet of the multi stage washing column is fluidly connected with a fresh water source.
By introducing fresh water into the multi stage washing column via the cold liquid inlet the gas/air ascended inside the multi stage washing column can be further cooled down and even more thermal energy of the gas/air can be extracted by condensation of the humidity due to the further cooling by the fresh liquid / fresh water introduced into the multi stage washing column via the cold liquid inlet. The amount of fresh liquid / fresh water introduced into the multi stage washing column is smaller than the amount of liquid/water introduced into the multi stage washing column via the hot liquid inlet and the intermediate temperature liquid inlet, respectively.
Further advantages, details and features of the present invention are explained in the description of the following embodiments, Thereby,

figure 1:: shows a schematic diagram of an example of a device for drying wetted material, wherein the device comprises a multi stage washing column; and
figure 2:: shows a schematic diagram of a device for drying wetted material according to an embodiment of the present invention, wherein the device comprises a multi stage washing column according to an embodiment of the use according to the present invention.

In the following description same reference numerals describe same elements and same features, respectively, so that a description of one element conducted with reference to one figure is also valid for the other figures, so that repetition of the respective feature is omitted.
Figure 1 shows a schematic diagram of an example of a device 100 for drying wetted material WM. Wetted material WM in the sense of the present invention can be wetted paper, wetted paint, wetted malt, or wetted food, so that there is no restriction regarding the nature of the wetted material WM. The present invention will be described in the following with regard to wetted paper as wetted material WM to describe the functionality of the device 100 for drying wetted material WM. Nevertheless, the device 100 for drying wetted material WM according to the present invention can also be used for drying wetted paint, wetted malt and wetted malt.
The device 100 for drying wetted material WM comprises at least one drying device 10 for accommodating the wetted paper WM, a multi stage washing column 20, and a heat pump 30. A liquid outlet 26 of the multi stage washing column 20 is fluidly connected with a first heat pump liquid inlet 31 and a first liquid outlet 32 of the heat pump 30 is fluidly connected with a hot liquid inlet 23 of the multi stage washing column 20. A second heat pump inlet 33 is fluidly connected with a hot fluid source which e.g. can be a source for steam generation and/or air providing a fluid e.g. exhibiting a temperature in the range of 105°C. A second heat pump outlet 34 is fluidly connected with a drying device gas inlet 11 and a drying device outlet 12 is fluidly connected with a gas inlet 21 of the multi stage washing column 20.
Due to the fluid connection of the multi stage washing column 20 with the heat pump 30 a heat cycle between the multi stage washing column 20 and the heat pump 30 is realized. The heat cycle is realized by a circulating liquid which e.g. can be water. The water circulates between the liquid outlet 26 of the multi stage washing column 20, the first heat pump liquid inlet 31, the first heat pump liquid outlet 32, and the hot liquid inlet 23 of the multi stage washing column 20. Thermal energy extracted from the water exiting the multi stage washing column 20 is transferred to the heat pump 30 and thermal energy extracted from the heat pump 30 is transferred to the medium (water/steam/air) entering the heat pump 30 via the second heat pump inlet 33, so that the medium exiting the heat pump 30 via the second heat pump outlet 34 can be used for drying the wetted paper. In the described embodiment the medium exiting the heat pump 30 via the second heat pump outlet 34 preferably exhibits a temperature in the range of 140°C to 150°C.
In the device 100 according to the shown example the pressure of the medium exiting the heat pump 30 via the second heat pump outlet 34 is in the range of 3 bar to 4 bar. The second heat pump outlet 34 is fluidly connected with a low pressure fluid pipe 70. The low pressure fluid pipe 70 can be fluidly connected with different thermal energy consumers of hot air / hot steam exhibiting a pressure of 3 - 4 bar, wherein these thermal energy consumers are not shown in figure 1.
As can be seen from figure 1 the low pressure fluid pipe 70 is fluidly connected with an intermediate pressure fluid pipe 80 via a compressor 50, which according to the shown example is realized as a steam compressor 50. More precisely the low pressure fluid pipe 70 is fluidly connected with an inlet 51 of the compressor 50, and an outlet 52 of the compressor 50 is fluidly connected with the intermediate pressure fluid pipe 80. The compressor 50 compresses the fluid (air and/or steam) fed from the low pressure fluid pipe 70 in a pressure range between 8 bar and 10 bar. The intermediate pressure fluid pipe 80 is fluidly connected with the inlet 11 of the drying device 10, so that the wetted paper WM inside the drying device 10 is dried by the pressurized medium, which also can be named gas and/or air and/or steam.
The mixture of air and steam exiting the drying device 10 via the outlet 12 of the drying device 10 enters the multi stage washing column 20 via the gas inlet 21. The mixture of air and steam exhibits a temperature in the range of 150°C and a dew point in the range of 85°C. The temperature of the water injected into the multi stage washing column 20 via the hot liquid inlet 23 exhibits a temperature in the range of 70°C.
Since the water injected via the hot liquid inlet 23 exhibits a lower temperature than the mixture of air and steam injected via the gas inlet 21 into the multi stage washing column 20, a very high percentage of the humidity of the air condensates when the air is cooled down by the water introduced into the multi stage washing column 20 via the hot liquid inlet 21. The liquid introduced into the multi stage washing column 20 via the hot liquid inlet 21 is heated by the condensation of the humidity of the air and by heat transfer from the air to the water. For that reason the temperature of the water collected at a bottom of the multi stage washing column 20 is considerably high (in the range of 80°C) and therefore the heat energy of the water can be very effectively used by the heat pump 30. Since the humidity absorption capacity of air rises exponentially with the temperature of the air, a very high percentage of the humidity is condensed out of the air in the first stage of the multi stage washing column 20 by cooling down the air with water exhibiting a temperature which is slightly below the dew point of the air injected via the gas inlet 21 of the multi stage washing column 20.
The air ascending inside the multi stage washing column 20 exhibits a reduced temperature, a reduced humidity and therefore a reduced dew point in the range of 65°C. Water exhibiting a temperature below the reduced dew point of the air ascended in the multi stage washing column 20 is introduced into the multi stage washing column 20 via the cold liquid inlet 25. In the mounting position (shown in figure 1) of the multi stage washing column 20 the cold liquid inlet 25 is positioned above the hot liquid inlet 23. Compared to the amount of water introduced into the multi stage washing column 20 via the hot liquid inlet 21 a reduced amount of water is introduced into the multi stage washing column 20 via the cold liquid inlet 25. This reduced amount of water is sufficient to condensate out a further percentage of humidity out of the air. Therefore, the water introduced into the multi stage washing column 20 via the cold liquid inlet 25 only slightly cools down the water collected at the bottom of the multi stage washing column 20.
The air exiting the multi stage washing column 20 via a gas outlet 22 exhibits a temperature in the range of 20°C to 40°C, preferably 30°C.
Figure 2 shows a schematic diagram of a device 100 for drying wetted material WM according to an embodiment of the present invention. The device 100 according to this embodiment exhibits all components and features of the device 100 according to the example of Figure 1. The device 100 according to the embodiment of the present invention further comprises a multi stage washing column 20 wish is realized as a 3-stage washing column 20. The washing column 20 further comprises an intermediate temperature liquid inlet 24, wherein the intermediate temperature liquid inlet (24) is positioned between the hot liquid inlet 23 and the cold liquid inlet 25.
The multi stage washing column 20 according to the embodiment of the present invention exhibits the advantage that thermal energy of air introduced into the multi stage washing column 20 via the gas inlet 21 can be even more effectively extracted, wherein the water collected at the bottom of the multi stage washing column exhibits a higher temperature, and wherein the overall liquid consumption required for cooling down the air and for drying the air is reduced. Since the water collected at the bottom of the multi stage washing column 20 exhibits a higher temperature, the thermal energy of the water can be more effectively transferred to a heat consumer 60.
The device 100 according to the embodiment of the present invention furthermore comprises a heat exchanger 40, wherein a first heat exchanger inlet 41 is fluidly connected with the first heat pump liquid outlet 32 and the hot liquid inlet 23 of the multi stage washing column 20. A first heat exchanger liquid outlet 42 is fluidly connected with the intermediate temperature liquid inlet 24 of the multi stage washing column 20, and a second heat exchanger liquid inlet 43 and a second heat exchanger liquid outlet 44 are fluidly connected with a heat energy consumer 60, so that thermal energy from the water introduced into the heat exchanger 40 via the first heat exchanger liquid inlet 41 is transferable to the heat energy consumer 60.
Due to the fluid connection of the multi stage washing column 20 with the heat exchanger 40 a heat cycle between the multi stage washing column 20 and the heat exchanger 40 is realized. The heat cycle is realized by circulating water circulating between the liquid outlet 26 of the multi stage washing column 20, the first heat pump liquid inlet 31, the first heat pump liquid outlet 32, the first heat exchanger liquid inlet 41, the first heat exchanger outlet 42 and the intermediate temperature liquid inlet 24 of the multi stage washing column 20. Thermal energy extracted from the water exiting the heat pump 30 via the first heat pump liquid outlet 32 is transferred to the heat exchanger 40 and thermal energy extracted from the heat exchanger 40 is transferred to a medium (for example water) circulating between the heat energy consumer 60 (for example a process water tank and/or a space heating) and the heat exchanger 40 via the second heat exchanger inlet 43 and the second heat exchanger outlet 44.
The temperature of the water entering the heat exchanger via the first heat exchanger inlet 41 can preferably be 70°C, and the temperature of the water exiting the heat exchanger 40 via the first heat exchanger outlet 42 is preferably 55°C. The dew point of the ascended air inside the multi stage washing column 20 in the area of the second stage, i.e. in the area of the intermediate temperature liquid inlet 24 is in the range of 60°C so that humidity is condensed out of this air by cooling it down with water injected via the intermediate temperature liquid inlet 24.
The temperature of the water injected into the multi stage washing column 20 via the cold liquid inlet 25 can preferably be 10°C. The dew point of the gas inside the washing column 20 in the area of the third stage, i.e. in the area of the cold liquid inlet 25 is approximately 40°C so that humidity is condensed out of this air by cooling it down with water injected via the cold liquid inlet 25.

Reference numerals

10: drying device
11: inlet (of the drying device)
12: outlet (of the drying device)
20: (multi stage) washing column
21: (washing column) gas inlet
22: (washing column) gas outlet
23: (washing column) hot liquid inlet / first washing column liquid inlet
24: intermediate temperature liquid inlet / second washing column liquid inlet
25: (washing column) cold liquid inlet / third washing column liquid inlet
26: (washing column) liquid outlet
30: heat pump
31: first heat pump liquid inlet
32: first heat pump liquid outlet
33: second heat pump inlet
34: second heat pump outlet
40: heat exchanger
41: first heat exchanger liquid inlet
42: first heat exchanger liquid outlet
43: second heat exchanger liquid inlet
44: second heat exchanger liquid outlet
50: (steam) compressor
51: inlet (of the compressor)
52: outlet (of the compressor)
60: heat consumer
70: low pressure fluid pipe
80: intermediate pressure fluid pipe
WM: wetted material / wetted paper

Claims

Device (100) for drying wetted material (WM), comprising
a) at least one drying device (10) for accommodating the wetted material (WM);

b) a multi stage washing column (20) with
- a gas inlet (21) for introducing a gas into the multi stage washing column (20),

- a gas outlet (22) for exiting the gas out of the multi stage washing column (20),

- a first washing column liquid inlet (23) for introducing liquid into the multi stage washing column (20),

- a third washing column liquid inlet (25) for introducing liquid into the multi stage washing column (20), and

- a liquid outlet (26) for exiting the liquid out of the multi stage washing column (20),
wherein in a mounting position of the multi stage washing column (20) the third washing column liquid inlet (25) is positioned above the first washing column liquid inlet (23),

- a second washing column liquid inlet (24),wherein the second washing column liquid inlet (24) is positioned between the first washing column liquid inlet (23) and the third washing column liquid inlet (25);

c) a heat pump (30), wherein
- the liquid outlet (26) of the multi stage washing column (20) is fluidly connected with a first heat pump liquid inlet (31) and a first liquid outlet (32) of the heat pump (30) is fluidly connected with the first washing column liquid inlet (23) of the multi stage washing column (20);

- a second heat pump inlet (33) is fluidly connected with a with a hot fluid source; and

- a second heat pump outlet (34) is fluidly connected with a drying device gas inlet (11) and a drying device outlet (12) is fluidly connected with the gas inlet (21) of the multi stage washing column (20)
and

d) a heat exchanger (40), wherein
- a first heat exchanger liquid inlet (41) is fluidly connected with the first heat pump liquid outlet (32) and the first washing column liquid inlet (23) of the multi stage washing column (20) ;

- a first heat exchanger liquid outlet (42) is fluidly connected with the second washing column liquid inlet (24) of the multi stage washing column (20); and

- a second heat exchanger liquid inlet (43) and a second heat exchanger liquid outlet (44) are fluidly connectable with a heat energy consumer (60), so that thermal energy from the liquid introduced into the heat exchanger (40) via the first heat exchanger liquid inlet (41) is transferable to the heat energy consumer (60).
Device (100) according to claim 1, characterized in that the device (100) further comprises a compressor (50) arranged between the second heat pump outlet (34) and the drying device gas inlet (11), wherein a compressor inlet (51) is fluidly connected with the second heat pump outlet (34) and a compressor outlet (52) is fluidly connected with the drying device gas inlet (11).
Device (100) according to any of the preceding claims, characterized in that the third washing column liquid inlet (25) of the multi stage washing column (20) is fluidly connected with a fresh water source.
Device (100) according to any of the preceding claims, characterized in that in the mounting position of the multi stage washing column (20) the gas outlet (22) is positioned above the gas inlet (21).
Device (100) according to any of the preceding claims, characterized in that in the mounting position of the multi stage washing column (20) each liquid inlet (23, 24, 25) is arranged at a different vertical position of the multi stage washing column (20).
Use of a multi stage washing column (20) with
- a gas inlet (21) for introducing a gas into the multi stage washing column (20),

- a gas outlet (22) for exiting the gas out of the multi stage washing column (20),

- a first washing column liquid inlet (23) for introducing liquid into the multi stage washing column (20),

- a third washing column liquid inlet (25) for introducing liquid into the multi stage washing column (20), and

- a liquid outlet (26) for exiting the liquid out of the multi stage washing column (20),

- a second washing column liquid inlet (24),
wherein in a mounting position of the multi stage washing column (20) the third washing column liquid inlet (25) is positioned above the first washing column liquid inlet (23), wherein the second washing column liquid inlet (24) is positioned between the first washing column liquid inlet (23) and the third liquid inlet (25),
wherein a liquid having a first temperature is introduced into the first washing column liquid inlet (23),
wherein a liquid having a second temperature is introduced into the second washing column liquid inlet (24),
wherein a liquid having a third temperature is introduced into the third washing column liquid inlet (25), and
wherein the first temperature is higher than the second temperature, and wherein the second temperature is higher than the third temperature.