DE202020106421U1 - Exhaust gas cleaning system - Google Patents

Abstract

Exhaust gas cleaning system (1) for cleaning exhaust gas (EG) on board a ship, the exhaust gas cleaning system (1) comprising:
a scrubber (7) arranged to scrub the exhaust gas (EG) with a scrubbing fluid (SF) circulating through the scrubber (7),
a first heat exchanger (3) arranged in connection with the washer (7) in order to cool the washing fluid (SF) circulating through the washer (7),
a circulation tank (5) arranged in communication with the washer (7) for supplying the washing fluid (SF) to the washer (7) and for receiving the washing fluid (SF) from the washer (7), and
a cleaning unit (11) which is arranged in connection with the circulation tank (5) in order to receive the washing fluid (SF) from the circulation tank (5) and separate it into a first and a second portion (SF1, SF2), the second portion (SF2) is more polluted than the first portion (SF1), wherein the exhaust gas cleaning system (1) is characterized in that
it further comprises a heating device (9) arranged in connection with the circulation tank (5) and the cleaning unit (11) to heat the washing fluid (SF) after it has left the circulation tank (5) and before it is removed from the Cleaning unit (11) is added.

Description

Technical part

The invention relates to an exhaust gas cleaning system for cleaning exhaust gases on board a ship, e.g. B. from a ship's engine, burner or boiler.

State of the art

Large ships are usually powered by engines that run on fuel that contains sulfur. The combustion of this fuel produces exhaust gases containing sulfur oxide (SOx). The exhaust typically also contains particles such as soot, oil and heavy metals, as well as nitrogen oxides (NOx). To reduce the impact of the exhaust gas on the environment, the exhaust gas should be cleaned before it is released into the atmosphere. For example, the exhaust gas could be passed through a washer in order to be washed with a washing fluid, the pollutants contained in the exhaust gas being collected in the washing fluid.

The scrubber could be a so-called open cycle scrubber and the scrubbing fluid could be sea water, using the natural alkalinity of the sea water to scrub the sulfur oxides from the exhaust gas. The seawater is then passed from the ocean through the scrubber to absorb SOx and suspended solids from the exhaust gas before directing it back into the ocean.

Alternatively, the scrubber could be a so-called closed circuit scrubber, which uses circulating fresh or sea water in combination with an alkaline agent such as sodium hydroxide (NaOH) or sodium carbonate (Na ₂ CO ₃ ) as a scrubbing fluid in order to wash out sulfur oxides and particles from the exhaust gas. In such a washer, the amounts of aqueous sulfite, sulfate salts and solid particles in circulating fresh or sea water gradually increase. In order to control the quality of the circulating fresh or sea water, a small amount of it can be replaced occasionally or continuously by clean fresh or sea water and either stored on the ship or discharged overboard after cleaning of particles.

When the hot exhaust gas comes into contact with the washing fluid inside the washer, it is cooled and large amounts of the water contained in the washing fluid are evaporated. This evaporated water leaves the scrubber together with the exhaust gas and can create an undesirable, visible exhaust gas plume on contact with the ambient air. According to a known solution to this problem, the exhaust gas containing the evaporated water is heated before it leaves the ship in order to make the exhaust plume less visible. However, the equipment used for this heating is large and expensive. It also consumes a lot of energy, which is negative from an ecological point of view.

Summary

It is an object of the present invention to provide an exhaust gas purification system for purifying exhaust gases on board a ship which at least partially solves the aforementioned problem. The basic concept of the invention is to cool the exhaust gas more strongly within the scrubber in order to reduce the amount of evaporated water that leaves the scrubber together with the exhaust gas. The exhaust system according to the invention is defined in the appended claims and is described below.

An exhaust gas purification system according to the present invention is provided for cleaning exhaust gases on board a ship. The exhaust gas cleaning system includes a scrubber arranged to scrub the exhaust gas with a scrubbing fluid that circulates through the scrubber. The exhaust gas purification system further comprises a first heat exchanger, a circulation tank and a purification unit. The first heat exchanger is arranged in communication with the washer to cool the washing fluid circulating through the washer. The circulation tank is arranged in connection with the washer to supply the washing fluid to the washer and to receive the washing fluid from the washer. The cleaning unit is arranged in connection with the circulation tank to receive the washing fluid from the circulation tank and to separate it into a first and a second part, the second part being more polluted, i.e. contains more particles than the first fraction. The exhaust gas purification system is characterized in that it further comprises a heating device. The heating device is arranged in connection with the circulation tank and the cleaning unit in order to heat the washing fluid after it has left the circulation tank and before it is received by the cleaning unit.

The exhaust gas cleaning system could be used for cleaning exhaust gases from a ship engine on board a ship, a ship burner on board a ship or a ship boiler on board a ship.

It should be emphasized that “communicating” and “communicating” throughout the text mean “communicating directly or indirectly” and “communicating directly or indirectly”, respectively. Similarly, “to receive” means “to deliver” etc. im entire text “received directly or indirectly” or “supplied directly or indirectly”.

Since the scrubbing fluid is circulated through the scrubber via the circulation tank of the inventive exhaust gas purification system, the scrubber is a so-called cycle scrubber. As previously mentioned, a closed cycle scrubber is typically operated with a wash fluid of fresh and / or sea water mixed with a suitable alkaline agent.

The cleaning unit can be arranged to receive a constant or intermittent flow of washing fluid from the circulation tank, which flow can vary over time.

The cleaning unit can comprise one or more separators and / or filters, for example a centrifugal separator such as a high-speed separator and / or a decanter and / or a membrane filter.

As mentioned above, in an exhaust gas purification system according to the present invention, the cooling of the exhaust gas is increased in order to reduce the amount of water of the washing fluid evaporated in the washer. Such increased exhaust gas cooling is achieved by means of increased cooling of the washing fluid circulating through the washer by means of the first heat exchanger. Depending, of course, on the prevailing ambient air conditions, exhaust gas that contains more water vapor will typically produce a more visible exhaust plume when leaving the ship than exhaust gas that contains less water vapor. By reducing the amount of water evaporated in the scrubber, the amount of water vapor that leaves the ship with the exhaust gas is reduced, making the ship a less visible exhaust plume.

As described in the introduction, an exchange of the washing fluid may be necessary in a scrubber with a closed circuit in order to control the quality of the circulating washing fluid. The washing fluid to be replaced can be cleaned of particles and then, depending on the prevailing circumstances, drained into the sea or into a storage tank. In order to be diverted, the washing fluid may have to meet certain criteria, e.g. it must not have a pH value that is too low and / or a turbidity value that is too high. Depending on which alkaline agent is contained in the washing fluid, a lowered temperature of the washing fluid during the treatment of the washing fluid in the cleaning unit can lead to an impairment of the solubility of the alkaline agent and consequently to the removal of the undissolved alkaline agent together with the particles. This, of course, is a waste of unused chemicals. In addition, the alkaline agent, again depending on which alkaline agent is contained in the washing fluid, can give the washing fluid a high turbidity value which can prevent the washing fluid from escaping.

Since the exhaust gas cleaning system according to the invention comprises a heating device for heating the washing fluid after it has left the circulation tank and before it is received by the cleaning unit, the washing fluid to be replaced can be heated by the cleaning unit before the treatment. The heating of the washing fluid can improve the solubility of the alkaline agent, whereby the alkaline agent can be prevented from ending up in the more polluted second portion and being wasted. Additionally / alternatively, by heating the washing fluid, its turbidity value can be reduced, whereby it is possible to divert the cleaner first portion of the washing fluid.

The exhaust gas cleaning system can further comprise means for adding an alkaline agent to the washing fluid. The alkaline agent can be refilled if necessary in order to optimize the efficiency of the exhaust gas cleaning system. For example, the means for supplying an alkaline agent to the washing fluid can be arranged, i. the alkaline agent can be replenished upstream of the circulation tank and downstream of the scrubber.

The alkaline agent can comprise various chemicals, for example magnesium oxide or magnesium carbonate. According to one embodiment of the invention, the alkaline agent comprises magnesium hydroxide, which has the advantage that the degree of crystallization of the sulfate salts formed in the washing fluid is relatively low even at a low temperature of the washing fluid.

The means for supplying an alkaline agent to the washing fluid may comprise a source of the alkaline agent and a pump for pumping the alkaline agent from the source to the washing fluid. The source of the alkaline agent could simply be a container containing the alkaline agent. The pump could be a screw pump which can reduce erosion from an abrasive alkaline agent. In addition, a screw pump is relatively less prone to clogging.

The exhaust gas cleaning system can further comprise a measuring device which is arranged to measure a value of a characteristic variable of the washing fluid, this value being lower, equal to or higher than a predetermined value Handling of the washing fluid can be dependent on an output of the measuring device.

The measuring device can be provided in connection with the heating device and the cleaning unit in order to measure the value of the characteristic variable of the washing fluid after it has been heated by the heating device and before it is received by the cleaning unit. The handling of the clean first portion of the washing fluid can be dependent on an output of the measuring device.

The measuring device can comprise a mass flow meter, and the parameter can be a density of the washing fluid. The density of the washing fluid depends on the salt content of the washing fluid.

The mass flow meter can be of any suitable type. According to an embodiment of the present invention, the mass flow meter is a Coriolis mass flow meter, which has the advantage of being an inline mass flow meter.

Alternatively or additionally, the measuring device can comprise a conductivity sensor, and the parameter can be a conductivity of the washing fluid. The conductivity of the washing fluid depends on the salt content of the washing fluid.

The cleaning unit can be in communication with the circulation tank in order to remove at least a part, i. to supply a portion of the first portion of the washing fluid to the circulation tank when the value of the parameter is below the predetermined value. If the value is relatively low, then the salinity of the scrubbing fluid may be relatively low and the purification of the cleaner first portion of the scrubbing fluid may be inconvenient for the proper operation of the emission control system. The cleaning unit can be arranged to deliver a constant or intermittent flow of washing fluid to the circulation tank, and the flow can vary over time.

The exhaust gas purification system can further comprise a water analysis unit which is arranged such that it determines a number 1 of parameter values of the first proportion of the washing fluid. The handling of the cleaner first portion of the washing fluid can depend on a performance of the water analysis unit. The parameter values determined by the water analysis unit can e.g. be the turbidity, the pH and the PAH concentration of the first portion of the washing fluid.

The cleaning unit can be in communication with the circulation tank in order to remove at least a part, i. to supply part of the first portion of the washing fluid to the circulation tank if at least one of the parameter values exceeds or corresponds to a corresponding limit value. In this way, the discharge of the first portion of the washing fluid can be prevented if certain criteria are not met, e.g. if the first part is not clean enough, which is beneficial from an ecological point of view. The cleaning unit can be arranged so that a constant or intermittent flow of washing fluid is supplied to the circulation tank, which flow can vary over time.

The cleaning unit can be arranged in such a way that at least part of the first portion of the washing fluid is fed to the circulation tank if the value of the parameter is below the predetermined value and / or at least one of the parameter values exceeds or corresponds to a corresponding limit value.

As mentioned above, the exhaust gas purification system can further comprise a water analysis unit which is arranged such that it determines a number ≥ 1 of parameter values of the first portion of the washing fluid. Furthermore, the exhaust gas cleaning system can be arranged so that it does at least some, i. a portion of the first portion of the washing fluid is ejected when each of the parameter values is below a corresponding limit value and / or the value of the parameter is above or equal to the predetermined value. For example, the first portion of the washing fluid can be discharged overboard or into an intermediate storage tank for later discharge overboard. Derived fluids can be replaced with fresh wash fluid. In this way, a salt concentration of the washing fluid circulating through the washer can be kept sufficiently low to ensure correct operation of the exhaust gas cleaning system.

The heating device for heating the washing fluid before it is received in the cleaning unit can comprise a second heat exchanger.

The first and second heat exchangers can be of any suitable type, e.g. Plate heat exchanger or tube bundle heat exchanger. Further, the first and second heat exchangers may be of the same type or of different types.

Still other objects, features, aspects and advantages of the invention will become apparent from the following detailed description and from the drawings.

Figure list

• 1 ist ein Blockschaltbild, das eine Abgasreinigungsanlage nach der Erfindung schematisch darstellt.

The invention will now be described in more detail with reference to the accompanying schematic drawing, wherein

• 1 Figure 3 is a block diagram schematically illustrating an exhaust gas purification system according to the invention.

Detailed description

1 shows an exhaust gas cleaning system 1 , with a first plate heat exchanger 3 , a circulation tank 5 , a washer 7th , a heater 9 in the form of a second plate heat exchanger 9 ' , a cleaning unit 11 , a water analysis unit 13th , a measuring device 15th in the form of a Coriolis mass flow meter 15 ' and means 17th for supplying an alkaline agent, here magnesium hydroxide. The means 17th for the supply of an alkaline agent in turn comprise a source 19th , in particular a container with an alkaline agent, here magnesium hydroxide, and a screw pump 21st . The emission control system 1 is configured to take EG exhaust gas from a marine diesel engine 23 cleans on board a ship (not shown).

Inside the washer 7th , which operates in a conventional manner not further described here, the exhaust gas EG is washed with a washing fluid SF in the form of fresh water mixed with magnesium hydroxide. Accordingly, the washer includes 7th an exhaust inlet 25th for taking up the exhaust gas EG from the engine 23 and an exhaust outlet 27 for the discharge of the washed exhaust gas EGW. The washing fluid SF is taken from the circulation tank 5 in the washer 7th , through the washer 7th for the absorption of pollutants from the exhaust gas EG for its purification, back into the circulation tank 5 and then back to the washer 7th etc. directed.

That from the engine 23 Ejected exhaust gas EG is very hot and is used to maintain a suitable temperature of the washing fluid SF in the first plate heat exchanger 3 who is in front of the washer 7th and after the circulation tank 5 , ie on the way from the circulation tank 5 to the washer 7th , is arranged, cooled with sea water. Due to the high temperature of the exhaust gas EG, the water contained in the washing fluid SF becomes in the washer when the washing fluid comes into contact with the exhaust gas EG 7th evaporates. The water vapor formed leaves the washer 7th and is discharged from the ship through a chimney together with the cleaned exhaust gas EGW. In order to reduce the visible plume that this moist, cleaned exhaust gas forms when it is released into the atmosphere, this is done by the scrubber 7th recycled washing fluid SF by means of the first plate heat exchanger 3 chilled more than usual. As a result, less water is evaporated in the scrubber, creating less moist, cleaned exhaust gas and consequently a less visible exhaust plume.

When the washing fluid SF through the scrubber 7th is recirculated, it becomes more and more polluted. To ensure efficient operation of the scrubber 7th To ensure that the washing fluid is not excessively soiled. Accordingly, part of the washing fluid SF becomes continuously out of the circulation tank 5 for cleaning in the cleaning unit 11 pumped. The cleaning unit 11 is a high speed separator which is arranged to separate the contaminated washing fluid into a cleaner first portion SF1 and a more contaminated second portion SF2. The second portion of SF2 is placed in a sludge tank for later disposal 29 directed. To have a sufficient amount of washing fluid in the circulation tank 5 To ensure this is filled with washing fluid to compensate for the pumped-out washing fluid. This refill could involve the addition of clean, fresh water from outside the emission control system 1 include. In this case, in order to ensure the proper operation of the exhaust system 1 To maintain proper properties of the wash fluid, replenishing the wash fluid would normally also include adding magnesium hydroxide to the wash fluid. Then magnesium hydroxide is made with the help of the screw pump 21st from the source 19th pumped into the wash fluid. Magnesium hydroxide is supplied downstream of the scrubber 7th and upstream of the circulation tank 5 . The washing fluid could alternatively / additionally take place “internally”; in this case the cleaner first portion SF1 of the washing fluid becomes SF from the cleaning unit 11 back to the circulation tank 5 directed. This is discussed further below.

As already mentioned, the use of magnesium hydroxide as an alkaline agent makes it possible to cool the washing fluid circulating through the washer more than usual without causing problems with crystallization. However, the relatively low solubility of magnesium hydroxide in water can result in the wash fluid containing undissolved magnesium hydroxide. In order to avoid that such undissolved magnesium hydroxide of the cleaning unit 11 is supplied and ends up in the more contaminated second portion SF2 of the washing fluid SF, in order to then be drained off, that is done by the cleaning unit 11 Washing fluid to be treated using water from a heat recovery system of the ship in the second heat exchanger 9 ' , the upstream of the cleaning unit 11 and downstream of the circulation tank 5 is arranged, ie on the way from the circulation tank 5 to the cleaning unit 11 , warmed. Through this Heating, undissolved magnesium hydroxide is dissolved in the washing fluid, so that it ends up instead in the cleaner first portion SF1 of the washing fluid SF, which, as already mentioned, goes into the circulation tank 5 can be traced back.

As already mentioned, the more heavily soiled second portion SF2 of the washing fluid SF is in the sludge tank 29 directed. What happens to the cleaner first portion SF1 depends on various factors, for example on the properties of the cleaner first portion SF1. As the wash fluid is recirculated through the scrubber, the amount of sulfate salts in the wash fluid gradually increases. To ensure the correct operation of the emission control system 1 To ensure that the salinity of the circulating washing fluid must not be too high. For this purpose the density of the cleaning unit 11 wash fluid SF to be treated with the aid of the Coriolis mass flow meter 15 ' measured in front of the cleaning unit 11 and after the second plate heat exchanger 9 ' , ie on the way from the second plate heat exchanger 9 ' to the cleaning unit 11 , is arranged. If the density is higher than or equal to a predetermined value, the salt content in the washing fluid is so high that the cleaner first portion SF1 of the washing fluid from the exhaust gas cleaning system 1 should be drained or discharged, depending on its further properties. However, if the density is lower than the specified value, the first portion SF1 of the washing fluid SF does not need to be blown off, and the first portion SF1 is instead used in an “internal” refill of washing fluid in the circulation tank 5 returned.

Blowing off or diverting the first portion SF1 from the exhaust gas cleaning system 1 takes place only when the density of the washing fluid is sufficiently high and the first portion SF1 of the washing fluid SF meets certain criteria. The latter is done by the water analysis unit 13th checked that after the cleaning unit 11 and in front of the circulation tank 5 is arranged. The water analysis unit 13th is arranged such that it determines a turbidity value, a pH value and a PAH concentration (polycyclic aromatic hydrocarbons) of the first portion SF1 of the washing fluid SF. If one or more of the turbidity values, the pH value and the PAH concentration exceed or fall below a corresponding limit value, e.g. 25 NTU, 6.5 or 2250 ppb, the first portion SF1 of the washing fluid SF is not derived, but the The first portion of SF1 is instead used in an “internal” refill of washing fluid in the circulation tank 5 returned. If, however, the turbidity value, the pH value and the PAH value are below the respective limit values and the density of the scrubbing fluid is sufficiently high, the first part will come from the exhaust gas cleaning system 1 drained or discharged overboard or into a temporary collection tank (not shown) for later discharge, e.g. if the ship is in an area where discharge overboard is prohibited.

Thus the washing fluid circulating through the scrubber is cooled more than normal, e.g. to 6 degrees C in order to reduce the visible exhaust plume from the ship's chimney. In order to enable such a low temperature of the washing fluid without disturbing the crystallization, magnesium hydroxide is used as an alkaline agent. To prevent undissolved magnesium hydroxide in the portion to be drained, i.e. in the second portion SF2, which comes out of the cleaning unit, the washing fluid to be treated in the cleaning unit is heated by means of the second plate heat exchanger, e.g. to 35 degrees C before it is fed to the cleaning unit. In addition to the solution of undissolved magnesium hydroxide in the washing fluid to be treated by the cleaning unit, the heating of the washing fluid also reduces the turbidity of the washing fluid and thus of the first portion SF1 of the washing fluid, so that a turbidity value is achieved that is low enough to reduce the To allow draining or the discharge of the first portion of the washing fluid more easily.

As already mentioned, the washing fluid circulating through the scrubber can be cooled with sea water, and of course, in order to allow more cooling than conventional, the sea water must be sufficiently cooled. The visibility of the exhaust plume is, as also already mentioned, dependent on the ambient air conditions, the exhaust plume typically being more visible, e.g. when the ambient air temperature is low. Usually a low sea water temperature is associated with a low ambient air temperature, which means that the above exhaust gas cleaning system is most effective when it is needed most.

The components of the exhaust gas cleaning system described above are connected to one another by suitable pipelines so that they can communicate with one another in the manner described above. In addition, the exhaust system described above may include additional components in order for it to function properly, such as pumps, valves, sensors, further water analysis units, control units, switching modules, etc. As an example, the exhaust system can be a pH meter or a sensor between the scrubber and the circulation tank for measuring the pH of the washing fluid. This pH meter can be used with the supply device if required 17th communicate for the supply of the washing fluid with magnesium hydroxide. The supply device 17th can also / alternatively be operated in response to a sulfur dioxide / carbon dioxide ratio of the cleaned exhaust gas.

The above-described embodiment of the present invention should be considered as an example only. A person skilled in the art recognizes that the embodiment discussed can be varied in various ways without departing from the inventive concept.

For example, the exhaust gas cleaning system could be operated with alkaline agents other than magnesium hydroxide, magnesium oxide. Furthermore, chemicals other than an alkaline agent can be added to the scrubbing fluid for optimized operation of the exhaust gas cleaning system, such as a flocculant or coagulant to improve the efficiency of the cleaning unit 11 .

The supply device 17th to supply the washing fluid with magnesium hydroxide does not need upstream of the circulation tank 5 and after the washer 11 to be arranged, but can be arranged elsewhere, e.g. it can be attached directly to the circulation tank 5 connected.

In the embodiment described above, the handling of the first portion of the washing fluid is dependent on the density of the washing fluid after heating and on the turbidity value, the pH value and the PAH concentration of the first portion of the washing fluid. In alternative embodiments, the handling of the first portion of the washing fluid can only depend on one or two of these parameters, on additional parameters and / or other parameters.

The wash fluid need not include fresh water and an alkaline agent, but instead may include sea water and an alkaline agent, or a combination thereof.

The flow of the washing fluid from the circulation tank to the cleaning unit does not have to be continuous, but can take place intermittently and at regular intervals or only when necessary.

The first plate heat exchanger 3 does not have to be placed upstream, ie before the washer, and downstream, ie after the circulation tank, but could instead be placed after the washer and before the circulation tank.

The heating device 9 does not have to be in the form of a second plate heat exchanger 9 ' but can have any shape. For example, the heater could 9 instead / additionally include an electric heater.

That from the cleaning unit 11 washing fluid to be treated need not be heated with water from a ship's heat recovery system, but can be heated with hot water or steam from any suitable source.

The measuring device 15th does not have to be in the form of a Coriolis mass flow meter 15 ' but can have any shape. For example, the measuring device 15th instead / additionally contain a conductivity sensor.

It should be emphasized that a description of the details that are not relevant to the present invention has been omitted and that the figures are only drawn schematically and not true to scale.

Claims (15)

Exhaust gas cleaning system (1) for cleaning exhaust gas (EG) on board a ship, the exhaust gas cleaning system (1) comprising: a washer (7) which is arranged to scrub the exhaust gas (EG) with a washing fluid (SF), that circulates through the washer (7), a first heat exchanger (3) arranged in connection with the washer (7) to cool the washing fluid (SF) circulating through the washer (7), a circulation tank (5), which is arranged in connection with the washer (7) to supply the washing fluid (SF) to the washer (7) and to receive the washing fluid (SF) from the washer (7), and a cleaning unit (11) in connection with the circulation tank (5) is arranged to receive the washing fluid (SF) from the circulation tank (5) and to separate it into a first and a second portion (SF1, SF2), the second portion (SF2) being more contaminated than that first portion (SF1), wherein the exhaust gas cleaning system (1) is characterized in that it further ei ne heating device (9) which is arranged in connection with the circulation tank (5) and the cleaning unit (11) in order to heat the washing fluid (SF) after it has left the circulation tank (5) and before it is removed from the cleaning unit ( 11) is recorded. Exhaust gas cleaning system (1) Claim 1 which further comprises means (17) for supplying an alkaline agent to the washing fluid (SF). An exhaust gas purification system (1) according to any one of the preceding claims, wherein the alkaline agent contains magnesium hydroxide. Exhaust gas cleaning system (1) according to one of the Claims 2 - 3 wherein the means (17) for supplying an alkaline agent to the washing fluid (SF) comprises a source (19) of the alkaline agent and a pump (21) for pumping the alkaline agent from the source (19) to the washing fluid (SF). Exhaust gas cleaning system (1) Claim 4 wherein the pump (21) is a screw pump. The exhaust gas purification system (1) according to any one of the preceding claims, further comprising a measuring device (15) which is arranged to measure a value of a characteristic quantity of the washing fluid (SF), this value being lower, equal to or higher than a predetermined value. Exhaust gas cleaning system (1) Claim 6 , wherein the measuring device (15) is arranged in connection with the heating device (9) and the cleaning unit (11) to measure the value of the parameter of the washing fluid (SF) after it has been heated by the heating device (9) and before it is taken up by the cleaning unit (11). Exhaust gas cleaning system (1) according to one of the Claims 6 - 7th , wherein the measuring device (15) comprises a mass flow meter (15 ') and the parameter is a density of the washing fluid (SF). Exhaust gas cleaning system (1) Claim 8 wherein the mass flow meter (15 ') is a Coriolis mass flow meter. Exhaust gas cleaning system (1) according to one of the Claims 6 - 7th , wherein the measuring device (15) comprises a conductivity sensor and the parameter is a conductivity of the washing fluid (SF). Exhaust gas cleaning system (1) according to one of the Claims 6 - 10 , wherein the cleaning unit (11) is connected to the circulation tank (5) in order to supply at least a part of the first portion (SF1) of the washing fluid (SF) to the circulation tank (5) when the value of the parameter is below the predetermined value. Exhaust gas purification system (1) according to one of the preceding claims, further comprising a water analysis unit (13) which is arranged such that it determines a number ≥ 1 of parameter values of the first portion (SF1) of the washing fluid (SF). Exhaust gas cleaning system (1) Claim 12 , wherein the cleaning unit (11) is connected to the circulation tank (5) in order to supply at least part of the first portion (SF1) of the washing fluid (SF) to the circulation tank (5) if at least one of the parameter values exceeds a corresponding limit value or is the same a corresponding limit value. Exhaust gas cleaning system (1) according to one of the Claims 6 - 11 , which further comprises a water analysis unit (13) which is arranged such that it determines a number ≥ 1 of parameter values of the first fraction (SF1) of the washing fluid (SF), wherein the exhaust gas cleaning system (1) is arranged so that there is at least one Part of the first portion (SF1) of the washing fluid (SF) is ejected when each of the parameter values is below a corresponding limit value and / or the value of the parameter is above or equal to the predetermined value. Exhaust gas cleaning system (1) according to one of the preceding claims, wherein the heating device (9) has a second heat exchanger (9 ').

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