DE102006004221A1 - Device and method for separating pollutants in the flue gas of a thermal plant - Google Patents

Abstract

A device for separating pollutants in the flue gas of a thermal plant, in particular waste, substitute fuel and biomass combustion plant, is described, in which at least one heating surface is provided for heat recovery from the flue gas, which is produced during the thermal conversion of a feed material. The device is characterized in that at least one deposition surface is provided in the device, which is connected upstream of the at least one heating surface in the direction of the flue gas. Furthermore, a method for separating pollutants in the flue gas is disclosed. With the present invention, it is possible to reduce the corrosion attack on the heating surfaces of a boiler, which can only be insufficiently protected against corrosion attack according to the prior art, to extend the service life of the heating surfaces, to improve the heat transfer of the downstream heating surface and to improve the flue gas side Reduce pressure loss to ultimately increase plant uptime.

Description

content The invention relates to a method and a device for deposition of pollutants in the flue gas of thermal systems, in particular Rubbish-, Substitute fuel or biomass incinerators.

In thermal systems are heating surfaces, in particular convective heating surfaces, provided in the flue gas stream. About these heating surfaces is the temperature of the flue gas gradually reduced and simultaneously the energy emitted by the flue gas in the form of heat to a Transfer medium. As heating units, in which heating surfaces are provided, be especially superheaters, Evaporator and so-called economizer used. Due to the chemical Composition of the flue gas and the entrained impurities in this, it comes to the heating surfaces Because of the prevailing conditions to attacks of the surfaces. These Attacks can be of a chemical nature, for example in the form of corrosion, or physical nature, for example by abrasion by the in the flue gas guided particles.

To counteract these attacks is for example in the DE 199 22 605 A1 proposed a method in which the temperature of the flue gas is adjusted by mixing the flue gas with other gases. A disadvantage of this method is that the reactions occurring when the temperature of the flue gas decreases can not be specifically influenced.

task Thus, the present invention is a method and an apparatus to provide, through the targeted protection of heating surfaces, especially convective heating surfaces the heating units are provided in a thermal plant can. In particular, the object of the invention is the corrosion attack on the heating surfaces to reduce.

Of the The invention is based on the finding that this task is solved can by putting the heating surfaces upstream reaction site for the flue gases is provided, whose conditions are adjusted specifically can be.

The Task is solved by an apparatus having the features of claim 1 and by a method having the features of claim 10. Advantages and features, the re the apparatus are described, apply - as applicable - accordingly for the Procedure and vice versa. Further embodiments of the invention arise from the dependent ones Dependent claims.

According to one In the first aspect, the invention therefore relates to a device for Removal of pollutants in the flue gas of a thermal plant, especially a garbage, Substitute fuel or biomass incinerator, in which at least a heating surface for heat recovery from the flue gas produced by the combustion of the feedstock, is provided. The device is characterized in that at least a deposition surface is provided in the device, which precedes the at least one heating surface is.

The deposition surface is an area, which projects into the flue gas stream. The deposition surface becomes thus flowed by the flue gas and can serve for the separation of pollutants from the flue gas. The deposition rate of the relevant pollutants at a in the Flue gas stream protruding surface is higher in terms of construction volume as for example on the boiler walls, where the flue gas flows past. Preferably, the deposition area of the first is different from boiler walls heating surface upstream.

The thermal plant usually has at least two boiler trains, these may be vertical and / or horizontal. The deposition surface can provided in such a thermal plant in a boiler train be upstream of the boiler train in which the heating surfaces are arranged. This upstream boiler train, for example, the second Show empty train. But it is also possible the deposition surface in the upstream Area of the first boiler train in which the heating surface to be protected is provided are to be arranged.

By doing the deposition surface the heating surface or the heating units in which provided the heating surfaces are upstream, this is the flue gas at a position exposed, at which the flue gas temperature higher than at the subsequent heating surface is. As a result, the deposition behavior is favored.

At the heating surfaces upstream deposition surface can the for a desired one In addition, reaction conditions required to be set specifically. Compared to a mixture of the flue gas with other gases, is the reaction site for the flue gas predetermined by the intended deposition surface. Preferably, at the deposition surface, the temperature of the flue gas and its components. This can be done by selective adjustment the surface temperature the deposition surface done.

The deposition surface preferably represents a pipe surface and that at least a pipe is connected to a media pipe. The choice of pipe surfaces as deposition surface allows one in the smallest possible space size surface where the flue gas can come into contact with the deposition surface and at the chemical and / or physical processes of the pollutants carried in the flue gas can take place. Particularly preferably, the deposition surface is formed by a tube bundle. By the connection of the at least one pipe to a media line the temperature of the pipe surface can be influenced from the outside. Especially the temperature difference between the flue gas and the pipe surface is through cooling of the tube increases, thereby in turn affects the separation of pollutants from the flue gas becomes.

The Media line can be part of a separate media loop. In this case lets Although the temperature is independent of further process parameters in the thermal system. On the other hand, the through the flue gas to the medium, through the deposition surface guided will, heat given off only be used conditionally. Alternatively, the media line to Supplying the deposition surface with the cycle of heat recovery be connected to the thermal system. This will record the recorded Heat optimal used.

The deposition surface is preferably in the effective range of a discharge funnel of the thermal Plant arranged. By this arrangement, deposits on the deposition surface may be after their detachment from the surface unhindered with other solid discharges, such as dusts removed from the plant and adhere to between the discharge and respectively transfer hopper and the deposition surface located surfaces is minimized.

Additionally or alternatively to the setting of a predeterminable temperature at the deposition surface this can be supplied with electric current. The device according to a embodiment therefore, a power source connected to the deposition surface is. By this power source, the deposition surface with e.g. be subjected to positive or negative direct current. hereby can electrically charged particles that are in the flue gas due to the high Temperature may be increased, additionally attracted by the deposition surface become.

The Device can according to the invention at least a cleaning device for cleaning the deposition surface have. The cleaning device to be provided for this purpose is not on a certain design limited. By providing a cleaning device, the layer thickness from the contaminants deposited on the deposition surface or pollutants are regulated. The layer thickness of these coverings or deposits is of particular importance, since the thickness Temperature on the outside the layer and thus the processes taking place there becomes. If the layer thickness is kept low, so the temperature on the outside of the lining or the deposition can be reduced. hereby in particular, the reaction rate of the pollutant conversion reduced. Thus, a sufficient separation of pollutants at the deposition surface guaranteed and at the same time prevents attack of the material of the deposition surface become. The deposition surface is also due to the cleaning of the surface so far from corrosion attacks protected, that subsequent to the deposition sulfation of chlorides from the flue gas that releases aggressive chlorine species through Removing the deposit can be prevented. This will be the downstream heating surfaces additionally protected against corrosive attack.

The Cleaning device is preferably from one of the side walls of a Boiler train of the thermal plant in which the flue gas is guided, introduced into the boiler train. Sidewalls in the sense of the invention, are all boiler walls, which limits the boiler interior to the sides of the boiler to the environment. by name These are the left and right side wall, the front and back wall as well if necessary, the funnels.

By the horizontal orientation of the cleaning device, which may for example be a lance, it is possible to bring the detergent in the immediate vicinity of the surface to be cleaned. Horizontal in the sense of the invention, an imaginary plane is perpendicular to the vertical, which in space also may deviate from this imaginary plane at a given angle, but without reaching the perpendicular.

The Cleaning effect is achieved by applying the cleaning medium, which preferably is a liquid represents, on the coverings and / or deposits resulting from the impurities in the flue gas form or have formed. By the Leidenfrost'sche phenomenon forms around the liquid drop introduced into the flue gas stream a steam jacket. Gases or vapors are bad heat conductors, so that the liquid drop despite the high ambient temperatures, even greater than 600 ° C not spontaneous evaporated. By this effect, the liquid drop reaches the deposition surfaces or on the adhering coverings and / or deposits. Thus, with the cleaning device the covering wets. The pads and / or deposits are, inter alia, by vaporizing the liquid cooled. This causes embrittlement and tensions in the rubbers and / or deposits, thereby solving them. In addition, the weight the pads increased by the application of the cleaning medium and favors so additionally the detachment the pads from the deposition surface.

One high pressure of the cleaning agent, the usual cleaning devices of need in which the detergent is at a distance to the cleansing surface is introduced, this is not required and damage to the surface by the impact of the cleaning agent under high pressure can be avoided. The required pressure depends on the cleaning requirements. The main criteria are the size of the deposition surface and the effective radius of the outlets. The cleaning medium is preferably under low pressure of less than 10 bar, preferably less than 6 bar from the cleaning device issued. The pressure is regulated so that this depends on the Distance to be adjusted to the deposition surface is adjusted. The pressure is set to a value that ensures that the cleaning medium impinges on the deposition surface. A considerable one Impulse on impact should be avoided. Depending on the orientation of the outlet (s) on the cleaning device The cleaning medium can also without pressure from the cleaning device be delivered. In this case, the cleaning medium is only too transported to the outlet and can there by gravity enter a deposition surface located below the cleaning device. In this case, the deposition surface becomes with the cleaning medium irrigated.

Farther the horizontal introduction of the cleaning device is advantageous because of this also surfaces can be achieved the under further surfaces, especially heating surfaces, are arranged. It is thus possible a deposition surface below in the flow direction the flue gas first heating surface, the one superheater or a so-called heat trap can represent, arrange and yet sufficiently clean. When introducing the cleaning device in the vertical direction would the above the deposition surface arranged heating surfaces access to the deposition area and thus make their cleaning difficult.

The introducing port for the Cleaning device in the side wall of the boiler is preferably in the flue gas direction before or after a deposition surface or arranged between at least two deposition surfaces. Is it? at the deposition surfaces around pipe surfaces of a Tube bundle, so the introduction opening is predominant between the tubes of the tube bundle intended.

The introducing port for the Cleaning device has a device for closing the insertion opening. This way it becomes possible the cleaning device, which may represent a lance may be to remove from the boiler train after cleaning completed is.

According to one In another aspect, the invention relates to a method of deposition of pollutants from a flue gas in a thermal plant, especially garbage, Replacement fuel and biomass incinerators. The procedure is characterized in that in the leadership of the flue gas at least one deposition surface to disposal is placed, which at least partially protrudes into the flue gas stream. By creating a deposition surface with such an orientation may be the removal of pollutants from the flue gas before reaching one of the heating surfaces elevated become. In particular, you can at the deposition surface related to the volume of construction more relevant pollutants are deposited, as on the boiler walls, where the flue gas flows past.

In contrast to the surfaces of the heating surfaces, which are provided for example in superheaters, evaporators, economizers or so-called heat traps, it is intended in the inventively provided deposition surface that pollutants deposit on this. The deposition surface can thus also be referred to as pollutant trap. Thus, the arrangement of eg pipes of pollutant trap so be chosen that the greatest possible separation of the harmful substances from the flue gas is achieved. The advantages of providing such a pollutant trap have already been described with reference to the device according to the invention.

Preferably the temperature of the deposition surface is adjusted so that these is lower than the flue gas temperature in the vicinity of the deposition surface. Especially Preferably, the temperature of the deposition surface is lower as the temperature of the deposition surface downstream heating surfaces.

The Setting the temperature of the deposition surface can be achieved by cooling the deposition surface done from the inside. For this purpose, cooling medium through the example tubular Abscheidungsfläche be performed.

Additionally or alternatively to the cooling can the deposition area be charged with electric power. The advantages of this measure have already been with reference to the device according to the invention described.

Preferably For example, the temperature at the deposition surface is maintained by cleaning the deposition surfaces. Through the continuity the temperature of the deposition surface, the chemical and / or physical processes at the deposition surface be specifically influenced. Is a cleaning step provided so can as a deposition surface also, for example, a heating surface, especially the heat trap, serve.

According to one embodiment is the cleaning medium, preferably a cleaning liquid, over a Cleaning device introduced and the cleaning device is aligned horizontally. Particular preference is given to a Such cleaning device, which may for example be a lance, the cleaning medium from the cleaning device in among others vertical direction. Thus, a vertical cleaning level defined, in which the deposits on the deposition surfaces removed or can be removed.

Especially Preferably, the cleaning device is in the flue gas direction or after a deposition area or between at least two deposition surfaces, e.g. Pipes of the deposition surface, brought. In the latter case can with suitable geometry of the cleaning device, in particular the outlet at the cleaning device, with a cleaning device at the same time at least two deposition surfaces or tubes getting cleaned. To introduce ensure the cleaning device between deposition surfaces to be able to In particular, low-level cleaning devices are used small diameter used.

The Cleaning medium is preferably water. With the method according to the invention, in particular when introducing the cleaning medium under low Pressure in the immediate vicinity to the deposition area, This cleaning agent may be sufficient to remove the coating on the deposition surface of this to remove. Aggressive detergents that damage the surface to lead could, are not mandatory.

The cleaning fluid is for example under low pressure, particularly preferably in Range of less than 10 bar, preferably less than 6 bar, discharged from the cleaning device.

The Cleaning device is during the cleaning of the deposition surface preferably in horizontal Direction moves. In this way, a cleaning level, the with vertical release of the cleaning agent in the vertical direction is moved along the deposition surface and so on the entire area cleaned in the same way and with the same intensity become.

The Cleaning is carried out according to the invention preferably while the operation of the thermal plant. This cleaning during the Operation of the thermal plant has the advantage of a shutdown the boiler load is not necessary. With the method according to the invention can over it beyond the detached one Surface of the deposition surfaces removed from the boiler alone or together with other discharges become. Due to the small amount of cleaning fluid, in the method according to the invention necessary, can the dusts and coverings usually discharged dry become. Continue to be during given the temperature conditions of the operation of the thermal plant, the for the detachment the pads from the deposition surface by heat extraction necessary.

With The present invention thus makes possible a method and a method To create a device to prevent corrosion on the heating surfaces of a Kessels, which according to the prior art, only inadequate Protected against corrosion can be to prevent the service life of the heating surfaces to extend Finally increase the plant operating times. Furthermore, in larger scope dusts be removed from the flue gas, whereby the subsequent heating surfaces less be occupied. This is with an improved heat transfer and a reduced flow resistance to count.

The Invention will be described again below with reference to the attached Illustrated illustrations, the possible embodiments of the present invention. In particular show:

1 a schematic representation of a waste incineration boiler with vertical boiler trains;

2 a schematic block diagram of an embodiment of a cleaning system;

3 a schematic representation of a waste incineration boiler with horizontal boiler trains;

4 a schematic representation of an embodiment of the deposition surface;

5 : a photograph of a crude pipe system; and

6 : a photograph of a pipe system cleaned in operation.

The present invention will be described essentially with reference to a countercurrent furnace with 4-pass vertical vessel. The schematic structure of such a boiler is in 1 shown. However, the invention can also be used in other firing and boiler types.

The thermal plant used in the 1 represents a waste incineration plant, has a furnace 15 , as well as four vertical boiler trains 16 . 17 . 18 and 19 on. The boiler trains 16 and 17 are here Leerzüge in which there is a transfer of heat by radiation on the walls of the boiler trains. To the empty trains 16 . 17 Close in flue gas direction R boiler trains 18 . 19 with convective heating surfaces. In the illustrated embodiment, in the third boiler train 18 a heat trap 21 and four superheaters 22.1 to 22.4 arranged. In the subsequent fourth boiler train 19 are four economizers 23.1 to 23.4 arranged. These heating units, which have convective heating surfaces, are designed as piping systems.

As a so-called "pollutant trap" is a pipe system 24 , which in the flue gas direction in front of the heating surfaces to be protected 21 . 22 . 23 is used in the flue gas stream.

The pipe system 24 is schematic in 4 shown. In this case, the pipe system 24 the heat trap 21 upstream. As it turned out 4 results, the pipe system can 24 be involved in the water / steam cycle of the boiler. This is indicated by the dashed line in the figure. The feed takes place in such a way that the temperature of the pipe wall of the pipe system 24 lower than that of the heating surfaces to be protected 22 (see 1 and 3 ). By, in relation to the environment, lower surface temperature of the pipe system 24 the solid, liquid or gaseous pollutants separate from the flue gas and strike as liquid and / or solid deposits on the pipe system 24 the pollutant trap down. In the 4 is still presented the possibility that the pipe system 24 is cooled by a separate from the water / steam cycle of the boiler circuit.

The deposition from the gas phase is based essentially on the condensation, in particular of chloridic gases. Some condensation temperatures are shown in Table 1. Table 1: Boiling and melting point temperatures of selected chlorides

The Deposition from the liquid and solid phase can be many different mechanisms subject [cf. Warnecke, R .: Corrosion under consideration of flow velocity and reaction enthalpy. In: Born, M .: Flue gas-side steam generator corrosion (Experience in mitigation). Freiberg: Publisher Saxonia Site Development and Management Company mbH, 2003]. Above all, the deposition subsequent sulfation The chlorides release aggressive chlorine species that are the pipe wall due to corrosion can. Another corrosion relevant mechanism is the solution of the Pipe material in liquid Chloride melts. If the tube wall temperature is kept low, so can one hand the pollutants are deposited on the pollutant trap and on the other hand can be at enough lower Pipe wall temperature of the pollutant trap the reaction rate the chemical, corrosive processes on the ground are reduced so much that technically and economically satisfactory service life of the Pollutant trap can be achieved. The result is a reduction the pollutant load for the downstream heating surfaces and thus also an increase in their service lives.

An optionally provided in the device according to the invention cleaning system is in 2 shown schematically. Through the cleaning system is the low-covering, and thus cooler surface of the pipe system 24 ensured. This cleaning system is based on a mainly horizontally guided lance 1 passing through the boiler wall into the boiler interior 16 to 19 is introduced. The geometry of the lance 1 is chosen so that the at least one outlet 2 to the points to be cleaned in the space of the pipe system 24 can get. The in the pipe system 24 introduced lance 1 is schematic in the 4 indicated. This extends the lance 1 into the picture plane.

To automate the cleaning process, for example, after entering the outlet opening 2 in the boiler interior 16 to 19 via a tax role 7 a pulse to open the solenoid valve 8th are given. By opening the solenoid valve 8th a defined amount of the cleaning medium is applied under defined pressure as evenly as possible to the surfaces to be cleaned.

It has been shown that even small amounts of untreated water at low form show good to very good cleaning effect. This improves if the cleaning trips are repeated more often and between the repetitions the boiler can regenerate in relation to the temperature. A boiler load reduction during cleaning is not necessary. The detached dusts and coverings can over the funnel 20 and the existing Kesselaustragsysteme (not shown) are easily discharged. Due to the small amount of water used, the dusts are conveyed dry. An introduction of water in the dust extraction is usually not given.

3 shows a further embodiment of a thermal plant in which the boiler trains are arranged horizontally. Also in this system is in front of the heating surfaces 21 . 22 . 23 a deposition surface in the form of a pipe system 24 brought in.

Finally, in the 5 and 6 the pipe system 24 shown with adherent pads. As can be seen from these photographs, the pads after cleaning in the area in which the cleaning device was introduced into the boiler room are significantly reduced. At the boiler wall is in the 6 to recognize the inlet opening for the cleaning device. Furthermore, in the 6 to recognize the pipes of the pipe system on the left side, whereas in an unpurified pipe system in 5 the pipes are not visible.

The The invention is not limited to the illustrated embodiment. With The invention generally relates to a method for the separation of pollutants created from flue gases in incinerators, in which a deposition surface, for example introduced in the form of a pipe system (pollutant trap) in the flue gas path is, this pipe system is in the boiler, in the installed position to be protected from the ones to be protected heating surfaces is located and is preferably integrated in the cycle of the boiler. In this case, the feed into the pipe system (pollutant trap) at a lower temperature than the ambient temperature of the downstream one heating surfaces done and by the lower surface temperature of the pipe system the pollutant trap the pollutants from the gas phase and as liquid and / or solid coverings precipitate on the pipe system of the pollutant trap. Will the Deposition surface, especially the pipe system, cleaned by a cleaning system, so can the solved by the pipe system dusts and vouchers generally dry through the boiler ash discharge systems be discharged. The selection of the parameters surface and Arrangement of the pipe system, temperature and mounting position can be at of the present invention are chosen so that these the intended operation the boiler only minor side effects in terms of parameters Have steam pressure, steam temperature and steam quantity of the boiler.

The Supply of the cleaning medium is preferably carried out via a horizontal lance, passing through the side wall of the boiler introduced and at the one nozzle is attached, which brings out the cleaning medium. Preferably the application of the cleaning medium takes place symmetrically, thus no reaction forces to effect the lance. The plant for cleaning the deposition surface can be mobile be formed. Furthermore, the system can be manually, semi-automatically or operated fully automatically. Preferably, the cleaning system a low design. This allows them between the pipes get the pipe systems.

Of the Exit angle of the cleaning medium will meet the requirements Geometry of the pipe systems and process engineering conditions customized.

Farther can End positions of the cleaning system to be specified. These end positions can be monitored for automatic operation become. In addition, the cleaning system can be used for one Automatic operation via a pressure monitor and / or a quantity regulation for have the cleaning medium. The entry depth of the cleaning system can be exceeded via the end positions of the cleaning system be managed. For The automatic operation of the cleaning system can be a control be provided.

1

lance

2

jet

3

flexible connection

4

drive

5

limit switch

6

limit switch

7

control roller

8th

magnetic valve

9

volume control

10

quantity measurement

11

pressure switch

12

control

13

pusher

14

barrier

15

firebox

16

first boiler pass

17

second boiler pass

18

third boiler pass

19

fourth boiler pass

20

funnel

21

heat trap

22

superheater

22.1

Superheater package 1

22.2

Superheater package 2

22.3

Superheater package 3

22.4

Superheater package 4

23

economizer

23.1

economizer 1

23.2

economizer 2

23.3

economizer 3

23.4

economizer 4

24

pipe system the pollutant trap

Claims (22)

Device for separating pollutants in the flue gas of a thermal installation, in particular a refuse, substitute fuel or biomass incinerator, in which at least one heating surface ( 21 . 22 . 23 ) is provided for recovering heat from the flue gas, which is formed during the combustion of the feedstock, characterized in that at least one deposition surface ( 24 ) is provided for the selective removal of pollutants in the device, the at least one heating surface ( 21 . 22 . 23 ) in the flue gas direction (R) is connected upstream. Apparatus according to claim 1, characterized in that the deposition surface ( 24 ) represents a pipe surface and the at least one pipe is connected to a media line. Apparatus according to claim 2, characterized in that the media line for supplying the deposition surface ( 24 ) is connected to the cycle of heat recovery respectively of the boiler. Device according to one of claims 1 to 3, characterized in that the deposition surface ( 24 ) in the effective range of a discharge funnel ( 20 ) of the thermal system is arranged. Device according to one of claims 1 to 4, characterized in that the device comprises a current source connected to the deposition surface ( 24 ) connected is. Device according to one of claims 1 to 5, characterized in that the device comprises at least one cleaning device ( 1 ) for cleaning the deposition surface ( 24 ) having. Apparatus according to claim 6, characterized in that the cleaning device ( 1 ) from one of the side walls of a boiler train ( 16 . 17 . 18 . 19 ) of the thermal system in which the flue gas is guided, in the boiler train ( 16 . 17 . 18 . 19 ) is introduced. Device according to one of claims 6 or 7, characterized in that the cleaning device ( 1 ) in the flue gas direction (R) before and / or after and / or between at least two deposition surfaces. Device according to one of claims 6 to 8, characterized in that the introduction opening for the cleaning device ( 1 ) has a means for closing the insertion opening. Method for separating pollutants from a flue gas in a thermal installation having at least one heating surface ( 21 . 22 . 23 ) for heat recovery from the flue gas, characterized in that in the leadership of the flue gas in front of the heating surface ( 21 . 22 . 23 ) at least one deposition surface ( 24 ) is provided for the selective separation of pollutants, which extends at least partially into the flue gas stream (R). A method according to claim 10, characterized in that the temperature of the deposition surface ( 24 ) is set to be lower than the flue gas temperature in the vicinity of the deposition surface. Method according to one of claims 10 or 11, characterized in that the deposition surface ( 24 ) is cooled. Method according to one of claims 10 to 12, characterized in that the deposition surface ( 24 ) is charged with an electric current. A method according to claim 10 to 13, characterized in that the temperature of the deposition area ( 24 ) by cleaning the deposition surface ( 24 ) is kept low. A method according to claim 14, characterized in that a cleaning medium via a cleaning device ( 1 ) and the cleaning device ( 1 ) is aligned horizontally. A method according to claim 15, characterized in that the cleaning medium from the cleaning device ( 1 ) is discharged in another vertical direction. Method according to one of claims 15 to 16, characterized in that the cleaning device ( 1 ) in the flue gas direction (R) before and / or after a deposition surface ( 24 ) and / or between at least two deposition surfaces. Method according to one of claims 15 to 17, characterized that the cleaning medium is water. Method according to one of claims 15 to 18, characterized in that the cleaning medium under a low pressure of less than 10 bar, preferably less than 6 bar, from the cleaning device ( 1 ) is delivered. Method according to one of claims 15 to 19, characterized in that the cleaning device ( 1 ) during the cleaning of the deposition surface ( 24 ) is moved in the horizontal direction. Method according to one of claims 14 to 20, characterized that cleaning during the Operation of the thermal system takes place. Method according to one of claims 15 to 21, characterized that the cleaning medium with the removed contaminants on the Discharge device or is discharged with the flue gas.