Method for cooling exhaust gas and exhaust gas cooling device

Abstract

The invention relates to a method for cooling exhaust gas comprising the steps of: a) providing fuel (24) in a combustion chamber (22), b) burning the fuel (24) to produce exhaust gas, c) introducing the exhaust gas into a liquid so that the liquid is heated by the exhaust gas and the exhaust gas is cooled by the liquid, d) introducing the heated liquid into a heat exchanger (46) and / or a heat engine, and e) cooling the heated liquid in the heat exchanger (46) and / or in the heat engine. The circulation line ensures that the liquid is conveyed through a Venturi arrangement below the liquid level into a container.

Description

[0001] The invention relates to a method for cooling exhaust gas. The invention also relates to an exhaust gas cooling device for carrying out such a method, as well as an exhaust gas treatment device for such an exhaust gas cooling device.

[0002] Exhaust gas can be produced, in particular, during the combustion of fuel in various systems such as combustion engines, power plants, industrial facilities, and heating systems. Exhaust gas can be especially reactive and corrosive at high temperatures, thus damaging various components in combustion systems. Several methods and devices are known in the prior art in which water, in the form of fine droplets or a fine mist, is sprayed into the exhaust gas stream. The aim is to clean the exhaust gas, primarily through chemical reactions. Pollutants and particles are to be removed from the exhaust gas before it is released into the environment, thereby reducing harmful emissions.

[0003] WO 00 / 07699 A2 discloses a process for removing nitrogen oxides from exhaust gas from a combustion plant. In this process, exhaust gas is brought into contact with water and oxygen, causing them to react to form nitric acid. The nitric acid is then reacted with a reducing agent to produce nitrogen and water.

[0004] Fuel is burned in combustion plants to make the chemical energy it contains usable. This occurs, for example, in a building's heating system, where the thermal energy released during combustion heats a fluid, such as water. This heated fluid serves as a transport medium for the thermal energy, which can be transported to and released where needed. Heat exchangers or heat engines are used for this purpose. Since combustion produces the aforementioned exhaust gases, which are at least partially harmful to the environment and can damage the system, efforts are made to utilize as much of the energy released during combustion as possible. The amount of usable energy relative to the total energy released determines the efficiency of the combustion plant.

[0005] The present invention is based on the objective of increasing the efficiency of such systems.

[0006] The invention solves the stated problem by a method for cooling exhaust gas comprising the steps: a) providing fuel in a combustion chamber, b) burning the fuel so that exhaust gas is produced, c) directing the exhaust gas into a liquid so that the liquid is heated by the exhaust gas and the exhaust gas is cooled by the liquid, d) directing the heated liquid into a heat exchanger and / or a heat engine and e) cooling the heated liquid in the heat exchanger and / or in the heat engine.

[0007] Fuel is supplied in a combustion chamber. Preferably, the fuel is a solid fuel, a liquid fuel, and / or a gaseous fuel, or contains these. The fuel is burned in the combustion chamber, producing exhaust gas. The exhaust gas typically contains a particulate component, such as soot and / or dust, as well as a gas component, such as nitrogen, oxygen, carbon dioxide, carbon monoxide, nitrogen oxides, in particular nitrogen monoxide and / or nitrogen dioxide, and / or sulfur dioxide. The exhaust gas is discharged from the combustion chamber and directed into a container holding a liquid. The exhaust gas is introduced into the liquid, so that the liquid is heated by the exhaust gas and the exhaust gas is cooled by the liquid. For this purpose, the exhaust gas has a higher temperature than the liquid when it is introduced.Preferably, the exhaust gas has a temperature of at least 100 °C, preferably at least 200 °C, and particularly preferably at least 300 °C when it is introduced into the liquid. For example, in heating stoves and fireplaces, the temperature is generally more than 235 °C and less than 350 °C.

[0008] Due to its lower density, the exhaust gas introduced into the liquid rises to the liquid's surface in the form of bubbles. This results in a large surface area to volume ratio, leading to particularly efficient heat transfer between the exhaust gas and the liquid. In this way, a maximum amount of the heat energy contained in the exhaust gas can be transferred to the liquid. This transfer occurs in the immediate vicinity of the gas bubbles, creating a temperature gradient within the liquid. The area of ​​the liquid directly surrounding the bubbles would then have a higher temperature than the rest of the liquid.

[0009] The rising bubbles cause turbulence in the liquid, resulting in a distribution of the heat energy transferred from the gas bubbles to the liquid. This cools the area of ​​the liquid immediately surrounding the bubbles and thus the exhaust gas, allowing it to absorb new energy from the exhaust gas. Simultaneously, it heats the portion of the liquid that is fed to the heat exchanger and / or the heat engine. The heated liquid is then fed to a heat exchanger and / or a heat engine.

[0010] The liquid is preferably water or oil.

[0011] A heat exchanger is understood to be, in particular, a device or arrangement for transferring thermal energy from one medium to another. Preferably, one medium is the heated liquid and the other medium is a fluid, more preferably water, oil, or air. A heat engine is understood to be a device for converting thermal energy into mechanical energy, in particular a gas turbine, a steam turbine, or a Stirling engine. In the heat exchanger and / or the heat engine, the heated liquid is used, for example, in a heat transfer process or a cycle, as the working medium. The thermal energy of the heated liquid is at least partially utilized, so that the heated liquid is cooled in the heat exchanger and / or the heat engine.Since at least some of the particle fraction sinks to the bottom of the liquid due to its greater density and is thus removed from the exhaust gas, the exhaust gas is additionally cleaned.

[0012] An advantage of the method according to the invention is that the energy efficiency of exhaust gas generation plants or, where applicable, upstream systems can be increased by utilizing the thermal energy of the exhaust gas. The invention makes it possible to cool the exhaust gas to such an extent that, when it is discharged from the liquid, it has a temperature of less than 50 °C, preferably less than 35 °C, and particularly preferably less than 25 °C. Preferably, the cooled exhaust gas is discharged into the atmosphere. Due to the low temperature of the exhaust gas, complex structural measures, such as the subsequent installation of a chimney, can be avoided. This makes the installation less complex and therefore more cost-effective. In addition, the efficiency of the system is improved by utilizing a portion of the thermal energy contained in the exhaust gas.

[0013] Preferably, the exhaust gas is fed through a duct into a container filled with the liquid up to a certain level. The advantage of this is that at least some of the exhaust gas containing solids settles at the bottom of the container over time, thus reducing the pollutant emissions from the system. Furthermore, some of the pollutants contained in the exhaust gas dissolve in the liquid, for example, water, and can then be chemically neutralized. Fine particulate matter in the exhaust gas is at least partially washed out and settles at the bottom of the container along with other solid components of the exhaust gas.

[0014] Preferably, if at least one drain criterion is present, or if sedimented sludge is continuously discharged from the container via a drain valve, the at least one drain criterion is advantageously a time period or a dimension of the particulate sludge, for example, the height of the particulate sludge. The sedimented sludge comprises, in particular, sedimented particles from the particulate fraction of the exhaust gas and / or a condensed portion of the gas fraction of the exhaust gas, which settles at the bottom of the container over time. Advantageously, the discharge of the sedimented sludge is automatic and / or automated. Alternatively or additionally, it is possible to discharge the sedimented sludge manually.

[0015] Preferably, continuously cooled exhaust gas is discharged from the container via an outlet opening. For this purpose, the outlet opening is located at least partially, but preferably completely, above the liquid level. As an alternative to this generally advantageous configuration, in certain embodiments it may be useful to discharge the cooled exhaust gas from the container only when at least one discharge criterion is met. Such a discharge criterion could be, for example, a time, a flow parameter such as a flow rate or flow velocity of the exhaust gas or liquid, or a pressure. Discharging upon reaching a discharge criterion is advantageous, for example, when the exhaust gas should not or cannot be released into the atmosphere, but rather, for instance, should or must be filled into containers.

[0016] A preferred embodiment of the method is characterized in that the heat exchanger and / or the heat engine is arranged in a circulation line and the liquid is returned to the container after passing through the heat exchanger and / or the heat engine.

[0017] Preferably, the supply line is a liquid line through which the liquid is fed into the container, wherein the supply line has a Venturi nozzle with a suction line through which the exhaust gas is fed into the supply line. Preferably, the Venturi nozzle has a constriction, wherein the suction line is arranged upstream of or within the constriction in the direction of liquid flow.

[0018] In this design, the exhaust gas is drawn from the combustion chamber into the supply line and thus into the liquid by the Venturi effect of the Venturi nozzle. This eliminates the need for an additional suction device, such as a pump. This also applies, for example, to a chimney used to vent exhaust gases from a fireplace, such as a wood-burning stove, in a building, particularly a residential building. A chimney utilizes the so-called chimney effect, which exerts a suction effect on the combustion chamber, which in this case can also be called a combustion chamber or firebox. Therefore, a functioning, and in particular, unblocked, chimney must be present if an open fireplace or other open firebox is to be operated in a living space. This prevents potentially toxic exhaust gases from the combustion chamber from entering the living space and posing a health hazard.If the exhaust gas is drawn out of the combustion chamber by the suction effect of the Venturi nozzle, a chimney is no longer necessary, which is particularly advantageous if a living space is to be retrofitted with a fireplace or other open fire.

[0019] The suction effect of the Venturi nozzle on the exhaust gas in the combustion chamber creates a negative pressure within the combustion chamber. The combustion chamber preferably has an air intake duct through which fresh air, and thus oxygen, can enter the combustion chamber. Preferably, this air intake duct has a check valve, so that air can only flow through the duct in one direction, namely into the combustion chamber. In a preferred embodiment, the negative pressure generated by the Venturi nozzle causes the check valve to open, allowing fresh, oxygen-rich air to enter the combustion chamber.

[0020] This also incorporates a safety mechanism that prevents exhaust gases from escaping the combustion chamber into a living space or other unwanted area. When the Venturi nozzle exerts its suction effect, the exhaust gas is drawn out of the combustion chamber, and simultaneously the check valve in the air intake duct opens, allowing fresh air to enter the combustion chamber. As soon as the Venturi nozzle ceases to exert its suction effect, for example, because no more liquid is flowing through the intake duct, no more exhaust gas is drawn out of the combustion chamber. This prevents the negative pressure from being created in the combustion chamber, so the check valve in the air intake duct remains closed, and no fresh air can enter the combustion chamber. As the fuel burns, the oxygen content in the combustion chamber is continuously reduced until the combustion process ceases due to lack of oxygen, and the fire, for example in the fireplace, goes out.Unlike a blocked chimney, which would result in exhaust gas from the combustion chamber entering the living space, the embodiment of the invention described here results in the fire going out without exhaust gas being able to enter the living space.

[0021] The same result can be achieved if, instead of the Venturi nozzle, a pump is used to pump the exhaust gas out of the combustion chamber, provided the combustion chamber has an air supply line with the check valve described here.

[0022] By altering the fluid flow through the Venturi nozzle, the strength of the suction effect can be changed and adjusted to a desired value. This is also possible with an adjustable pump whose suction capacity can be varied. In both cases, this allows the degree of negative pressure in the combustion chamber, caused by the achieved suction effect, to be adjusted. If the air intake line has an adjustable check valve, the amount of fresh air drawn into the combustion chamber through the intake line can be controlled by adjusting the suction effect. A check valve whose flow rate depends on the pressure differential on both sides of the valve is advantageous for this purpose. The greater the pressure differential, the more air can flow through the check valve into the combustion chamber. In this way, the combustion intensity within the combustion chamber can be adjusted.

[0023] Preferably, the circulation line includes the supply line. Particularly preferably, the heat exchanger and / or the heat engine is arranged upstream of the Venturi nozzle in the direction of fluid flow.

[0024] Advantageously, combustion air is supplied to the combustion chamber via an air intake duct, preferably in which a non-return valve is arranged. Preferably, a heating duct is arranged on and / or in the combustion chamber, in which a heat transfer medium to be heated flows. Preferably, the heat transfer medium comprises or is water, steam, air, and / or oil.

[0025] According to a second aspect, the invention solves the stated problem by means of an exhaust gas cooling device for carrying out the method according to the invention, comprising a) an exhaust gas generation device with i) a combustion chamber for burning a fuel to generate exhaust gas and ii) a discharge for discharging exhaust gas from the combustion chamber, and b) an exhaust gas treatment device with i) a container which is filled with a liquid up to a certain liquid level, ii) a supply line for directing exhaust gas into the container, which is fluidically connected to the discharge of the exhaust gas generation device, and c) a heat exchanger and / or a heat engine, wherein the heat exchanger and / or the heat engine is fluidly connected to the container.

[0026] Advantageously, the exhaust gas cooling device has a circulation line for circulating heated liquid, which is fluidically connected to the container and in which the heat exchanger and / or the heat engine is arranged.

[0027] Preferably, the supply line opens into the container via an inlet opening, the inlet opening being preferably located below the liquid level.

[0028] Advantageously, the container has an outlet opening for releasing cooled exhaust gas, which is located at least partially, but preferably completely, above the liquid level. Preferably, the outlet opening is fluidically connected to an exhaust gas line. Preferably, the exhaust gas is automatically discharged, particularly by means of overpressure within the container. Alternatively or additionally, a pump for conveying the exhaust gas from the container is arranged on the exhaust gas line.

[0029] Preferably, the outlet opening also serves as an overflow for draining excess liquid from the container. Alternatively or additionally, the container has a separate overflow for draining excess liquid from the container.

[0030] Preferably, a filling line for filling the container with liquid is arranged on the container. Preferably, a filling valve is arranged in the filling line, by which the flow of liquid through the filling line into the container can be adjusted.

[0031] Preferably, the exhaust gas cooling device has a drain valve for draining sedimented sludge from the container. Preferably, the drain valve is arranged in a lower region of the container, particularly on the underside of the container.

[0032] Advantageously, the exhaust gas cooling device includes a control unit configured to open and close the drain valve. Preferably, the container includes a sensor arranged and configured to detect the sedimented sludge and / or its height, with the draining of the sedimented sludge occurring based on the sensor data. Alternatively or additionally, the draining of the sedimented sludge can occur based on time and / or a mass flow rate of the exhaust gas and / or liquid.

[0033] Preferably, the supply line is a liquid line comprising a Venturi nozzle with a suction line, wherein the suction line is fluidly connected to the outlet of the exhaust gas generation device and the Venturi nozzle is arranged and configured to draw in the exhaust gas from the combustion chamber and to direct the exhaust gas via the suction line into the supply line.

[0034] Advantageously, the circulation line includes the supply line. The heat exchanger and / or the heat engine is then preferably arranged in the circulation line upstream of the Venturi nozzle, particularly upstream of the constriction, in the direction of fluid flow.

[0035] Preferably, the inlet pipe has a widening downstream of the Venturi nozzle in the direction of liquid flow. This widening is characterized in particular by the fact that the inlet pipe has a smaller internal cross-sectional area upstream of the widening than downstream of the widening. This allows for a longer residence time of the exhaust gas in the liquid with a constant inlet pipe length, thus achieving a longer heat transfer time between the exhaust gas and the liquid.

[0036] Alternatively or additionally, at least one flow control element, such as one or more orifice plates, screens and / or wire meshes, is arranged in the supply line and / or in the container, which is designed and configured to increase the residence time of the exhaust gas in the liquid.

[0037] Advantageously, the exhaust gas generation device has an air intake line for supplying combustion air to the combustion chamber. Preferably, a check valve is arranged in the air intake line. Preferably, a pump for conveying the combustion air is arranged in the air intake line. Alternatively, no pump is arranged in the air intake line. In this case, the combustion air is conveyed into the combustion chamber by the suction of the Venturi nozzle in the intake line.

[0038] Preferably, the exhaust gas cooling device includes an exhaust gas aftertreatment device for treating the exhaust gas, which is arranged downstream of the exhaust gas treatment device in the direction of exhaust gas flow. Preferably, the exhaust gas aftertreatment device includes at least one catalyst. Preferably, the at least one catalyst is a three-way catalyst, a reduction catalyst (SCR catalyst), an oxidation catalyst, or a particulate filter.

[0039] Preferably, the exhaust gas aftertreatment device includes a further container filled with another liquid, preferably water or comprising water, up to a certain liquid level. Preferably, photosynthetic organisms, in particular algae, are arranged in the further container for at least short-term absorption of carbon dioxide and for converting the carbon dioxide by photosynthesis. In particular, the photosynthetic organisms can be harvested and dried and subsequently used as fuel in the combustion chamber of the exhaust gas generation device.

[0040] Advantageously, the further container has a wall that is at least partially, but preferably completely, transparent. Alternatively or additionally, the further container is open on one side and / or has at least one opening for letting light into the further container.

[0041] The invention also solves the stated problem by means of an exhaust gas treatment device for an exhaust gas cooling device according to the invention.

[0042] The accompanying figures illustrate exemplary embodiments of the invention. They show: Figure 1 - a schematic representation of an exhaust gas cooling device according to a first embodiment of the present invention and Figure 2 - a schematic representation of an exhaust gas cooling device according to a second embodiment of the present invention.

[0043] The in Figure 1The exhaust gas cooling device 10 shown comprises an exhaust gas generation unit 20 and an exhaust gas treatment unit 30. The exhaust gas generation unit has a combustion chamber 22 in which a fuel 24 is burned. Air is supplied to the combustion chamber 22 via an air supply line 21. A check valve 23 is arranged in the air supply line 21, which prevents the backflow of fluids, in particular exhaust gas and air supply.

[0044] A heating line 25 with a heating chamber 27 is arranged at the combustion chamber 22. A heat transfer pump 28 for circulating a heat transfer medium, for example water, is arranged in the heating line 25. The heat transfer medium is heated by the heat generated during the combustion of the fuel 24. The heated heat transfer medium is conveyed via the heating line 25 to a heat exchanger 46 arranged in the heating line 25 and then back into the heating chamber 27.

[0045] During combustion, exhaust gas is produced, which is discharged from the combustion chamber 22 via a line 26 and conveyed to the exhaust gas treatment unit 30. The exhaust gas treatment unit has a container 32, which is filled with a liquid up to a certain liquid level, and a supply line 34 for directing exhaust gas into the container 32. The supply line 34 is fluidically connected to the line 26 of the exhaust gas generation unit 20.

[0046] In the illustrated embodiment, the supply line 34 is designed as a liquid line in which a Venturi nozzle 42 with a suction line 44 is arranged. The suction line 44 is fluidically connected to the outlet 26 of the exhaust gas generation device 20. Due to the Venturi effect, a negative pressure is created in the liquid-filled Venturi nozzle 42, causing exhaust gas to be drawn in via the suction line 44 and fed into the supply line 34. The liquid and the exhaust gas are then conveyed via the supply line 34 into the container 32.

[0047] As a result of heat transfer between the liquid and the exhaust gas, the liquid is heated and the exhaust gas is cooled. In the container 32, at least some of the exhaust gas rises over time and collects above the liquid level. The container 32 has an outlet opening 38 for releasing cooled exhaust gas from the container 32, which, in the illustrated embodiment, is partially located above the liquid level. In this example, the outlet opening 38 also serves as an overflow for draining excess liquid from the container 32. For this purpose, the outlet opening 38 is connected to both an exhaust gas line 48 and a wastewater line 49. As an additional option, a gas pump 50, for example a diaphragm pump, can be installed in the exhaust gas line 48 to assist in the discharge of the gas.This is particularly advantageous if, during downstream exhaust gas utilization, the back pressure in the exhaust gas line 48 is or could be too high compared to the internal pressure of the container. Alternatively or additionally, in this case it may be advisable to wait until a discharge criterion is met before the exhaust gas is fed into the utilization process. One such criterion is, for example, reaching a sufficiently high internal pressure of the container.

[0048] In the container 32, flow-directing elements 31 in the form of perforated plates are arranged, which lengthen the flow path of the exhaust gas and thus increase the residence time of the exhaust gas in the liquid.

[0049] In the illustrated embodiment, the supply line 34 is designed as part of a circulation line 36 in which a heat exchanger 46 is arranged. Alternatively or additionally to the heat exchanger 46, a heat engine (not shown) can be arranged in the circulation line 36. In the illustrated embodiment, the fluid heated by the exhaust gas is conveyed in the circulation line 36 to the heat exchanger 46 and / or the heat engine by means of a circulation pump 37. In the heat exchanger 46 and / or the heat engine, the thermal energy of the heated fluid is utilized, causing the fluid to cool. Downstream of the heat exchanger 46 and / or the heat engine, the Venturi nozzle 42 is arranged in the circulation line. Downstream of the Venturi nozzle 42, the supply line 34 has a widening 43.The inner cross-sectional area of ​​the supply line 34 is larger downstream of the expansion 43 than upstream of the expansion 43 in the direction of fluid flow. Due to the larger cross-sectional area, the velocity of the fluid flow in the supply line 34 decreases, thus increasing the residence time of the exhaust gas in the liquid and, in particular, in the supply line 34.

[0050] Over time, particles, particularly those from the particulate matter of the exhaust gas and / or a condensed portion of the gaseous content of the exhaust gas, settle as particulate sludge at the bottom of the container. Therefore, a drain valve 40 is located in the lower part of the container 32 to remove the settled particulate sludge.

[0051] In the illustrated embodiment, a filling line 33 for filling the container 32 with liquid is arranged on the container 32. A filling valve 35 is arranged in the filling line 33, by which the flow of liquid via the filling line 33 into the container 32 can be adjusted.

[0052] Figure 2Figure 1 shows an exhaust gas cooling device 10 according to a second embodiment, comprising an exhaust gas generation unit 20 and an exhaust gas treatment unit 30. The exhaust gas generation unit 20 has a combustion chamber 22. Air is supplied to the combustion chamber 22 via an air supply pump 29 and an air supply line 21. The air supply line has a check valve 23 to prevent backflow of the air supply and / or exhaust gas. A fuel 24 is burned in the combustion chamber 22. The heat generated during combustion heats a heat transfer fluid flowing in a heating chamber 27. The heating chamber 27 is part of a heating line 25 in which the heat transfer fluid flows. The heat transfer fluid is pumped in the heating line 25 by a heat transfer pump 28. The heat transfer fluid is pumped from the heating chamber 27 via the heating line 25 to a heat exchanger 46 and from the heat exchanger 46 back to the heating chamber 27.

[0053] During the combustion of fuel 24 in combustion chamber 22, exhaust gas is produced, which is discharged from combustion chamber 22 via a duct 26. The duct 26 is fluidically connected to an inlet 34 of the exhaust gas treatment device 30. The inlet 34 leads via an exhaust gas distributor 47 into a container 32, which is filled with a liquid, for example water, up to a certain liquid level. The exhaust gas distributor 47 is located below the liquid level. The exhaust gas therefore flows upwards in the container 32.

[0054] Flow-directing elements 31 in the form of perforated metal sheets are arranged in the container. These elements increase the flow path of the exhaust gas towards the liquid level, thus increasing the residence time of the exhaust gas in the liquid. The exhaust gas is cooled by contact with the liquid, while the liquid is heated as a result.

[0055] The container 32 is fluidically connected to a circulation line 36 in which a heat exchanger 46 is arranged. The heated liquid is pumped by a circulation pump 37 through the circulation line 36 to the heat exchanger 46, where it is cooled and then flows back into the container 32.

[0056] Container 32 has a pipe on its underside containing a drain valve 40 for draining sedimented sludge. The sedimented sludge consists, for example, of sedimented particles from the particulate matter of the exhaust gas and / or a condensed portion of the gaseous content of the exhaust gas, which settles at the bottom of container 32 over time.

[0057] The container 32 has an outlet opening 38 on its upper side for releasing cooled exhaust gas from the container 32. The outlet opening 38 is fluidically connected to an exhaust gas line 48, through which the exhaust gas is, for example, released into the environment or fed to an exhaust gas aftertreatment system.

[0058] The container 32 also has an overflow opening 45 in its upper area, which is fluidically connected to a wastewater pipe 49. Excess liquid can be drained from the container 32 via the wastewater pipe 49.

[0059] A filling line 33 for filling the container 32 with the liquid is arranged on the container 32. A filling valve 35 is arranged in the filling line 33. Reference symbol list

[0060] 10 Exhaust gas cooling device 20 Exhaust gas generation unit 21 Air intake duct 22 Combustion chamber 23 Check valve 24 Fuel 25 Heating duct 26 Drain 27 Heating chamber 28 Heat transfer pump 29 Air intake pump 30 Exhaust gas treatment unit 31 Flow control element 32 Tank 33 Filling line 34 Supply line 35 Filling valve 36 Circulation line 37 Circulation pump 38 Outlet opening 40 Drain valve 42 Venturi nozzle 43 Expansion 44 Suction line 45 Overflow opening 46 Heat exchanger 47 Exhaust gas distributor 48 Exhaust line 49 Wastewater line 50 Gas pump

Claims

1. A method for cooling exhaust gas, comprising the steps of: a) providing fuel (24) in a combustion chamber (22), b) burning the fuel (24) to produce an exhaust gas, c) feeding the exhaust gas into a liquid so that the liquid is heated by the exhaust gas and the exhaust gas is cooled by the liquid, d) feeding the heated liquid into a heat exchanger (46) and / or a heat engine, and e) cooling the heated liquid in the heat exchanger (46) and / or in the heat engine.

2. Method according to claim 1, characterized in that the exhaust gas is fed through a feed line (34) into a container (32) which is filled with the liquid up to a liquid level, the exhaust gas entering the container below the liquid level.

3. Method according to claim 2, characterized in that when at least one discharge criterion is present, particle sludge is discharged from the container (32) via a discharge valve (40).

4. Method according to claim 2 or 3, characterized in that when at least one outlet criterion is present or continuously cooled exhaust gas is discharged from the container (32) via an outlet opening (38) of the container (32) which is arranged above the liquid level.

5. Method according to one of the preceding claims, characterized in that the heat exchanger (46) and / or the heat engine is arranged in a circulation line (36) and the liquid is passed back into the container (32) after passing through the heat exchanger (46) and / or the heat engine.

6. Method according to one of claims 2 to 5, characterized in that the supply line (34) is a liquid line through which the liquid is fed into the container (32), wherein the supply line (34) has a Venturi nozzle (42) with a suction line (44) via which the exhaust gas is sucked in from the combustion chamber (22) and fed into the supply line (34).

7. Method according to claim 6, characterized in that the circulation line (36) has the supply line (34).

8. An exhaust gas cooling device (10) for carrying out a method according to any one of the preceding claims, comprising a) an exhaust gas generating device (20) with i) a combustion chamber (22) for burning a fuel (24) to generate exhaust gas and ii) a discharge line (26) for discharging exhaust gas from the combustion chamber (22), and b) an exhaust gas treatment device (30) with i) a container (32) filled with a liquid up to a liquid level, ii) a feed line (34) for feeding exhaust gas into the container (32), which feed line is fluidically connected to the discharge line (26) of the exhaust gas generating device (10), and c) a heat exchanger (46) and / or a heat engine, wherein the heat exchanger (46) and / or the heat engine is fluidically connected to the container (32).

9. Exhaust gas cooling device (10) according to claim 8, characterized bya circulation line (36) for circulating heated liquid, which is fluidly connected to the container (32) and in which the heat exchanger (46) and / or the heat engine is arranged.

10. Exhaust gas cooling device (10) according to claim 9, characterized in that the container (32) has an outlet opening (38) for discharging cooled exhaust gas from the container, which is arranged at least partially, but preferably completely, above the liquid level.

11. Exhaust gas cooling device (10) according to one of the preceding claims, characterized by a drain valve (40) for draining sedimented particle sludge from the container (32).

12. Exhaust gas cooling device according to one of the preceding claims, characterized in thatthe supply line (34) is a liquid line which has a Venturi nozzle (42) with a suction line (44), wherein the suction line (44) is fluidically connected to the discharge line (26) of the exhaust gas generating device (20) and the Venturi nozzle (42) is arranged and configured to suck in the exhaust gas from the combustion chamber (22) and to feed the exhaust gas via the suction line (44) into the supply line (34).

13. Exhaust gas cooling device (10) according to claim 12, characterized in that the circulation line (36) has the supply line (34).

14. Exhaust gas treatment device (20) for an exhaust gas cooling device (10) according to one of claims 8 to 13.

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