WO2007085491A2

WO2007085491A2 - Method and device for cleaning heating surfaces in thermal plants

Info

Publication number: WO2007085491A2
Application number: PCT/EP2007/000752
Authority: WO
Inventors: Ragnar Warnecke; Volker Müller; Odulf Reufer
Original assignee: Gks - Gemeinschaftskraftwerk Gmbh
Priority date: 2006-01-30
Filing date: 2007-01-29
Publication date: 2007-08-02
Also published as: DE202007019690U1; DE102006004222A1; WO2007085491A3; EP1979678A2

Abstract

The invention relates to a device for cleaning the heating surfaces in a thermal plant, the latter being equipped with at least one heating surface for obtaining heat from the flue gas that is produced during the thermal conversion of a feed material. The device is characterised in that at least one cleaning device is provided for at least one of the heating surfaces, said cleaning device being introduced into the gas-conducting boiler flue of the thermal plant from one of the side walls of said flue. The invention also relates to a method for cleaning said heating surfaces. The invention permits deposits in conduit systems such as superheaters, economisers and evaporators to be eliminated during the operation of the boiler, thus optimising the thermal transfer, reducing the increase of pressure losses in the boiler interior during uninterrupted operation and/or allowing the removal of pollutants from the conduits.

Description

description

Method and device for cleaning heating surfaces in thermal

Attachments

Contents of the invention is a method and an apparatus for cleaning heating surfaces in a thermal plant.

In thermal systems, in particular waste, substitute fuel and biomass incinerator, heating surfaces, in particular convective heating surfaces, are provided in the flue gas stream. These heating surfaces, the temperature of the flue gas is gradually reduced and at the same time transmit the energy emitted by the flue gas in the form of heat to a medium. As functional heating units in which heating surfaces are provided, in particular superheaters, evaporators and so-called economizers are used. In thermal plants, solid and / or pasty fuels used herein may form deposits on the heating surfaces. These deposits lead to a reduction in the heat transfer to the heating surfaces, also by narrowing the flue gas flow cross-sections to increase the flow resistance and can also lead to damage to the surfaces of the heating surfaces, for example, by corrosion.

The thermal systems, which are designed in particular as boiler systems, are usually run for cleaning when the flue gas temperature at the boiler outlet exceeds the permissible flue gas temperature of the downstream flue gas cleaning system or the pressure drop through the economizer, evaporator or superheater secure operation with stable

Negative pressure in the smoke gas-charged boiler interior makes impossible or a Damage in the boiler plant occurs. These business interruptions have a decisive influence on the availability of the incinerator and thus on the economic efficiency.

For the purification of the convective functional heating units, in which the

Heating surfaces are usually formed surfaces of pipes of a pipe system or a tube bundle, various cleaning systems have been developed and used with varying degrees of success.

A significant distinction between the cleaning systems is the achievement of cleaning without or with the use of additional cleaning media. The following discussion refers to the systems used to clean convective heating surfaces, and more specifically to the most commonly used systems, namely percussion and steam blowers.

The group of striking mechanisms, essentially knockers, vibrators and hammer mills, bring a shock impulse to the pipe systems from the outside. This method is based on the principle of perverting. However, this requires hard, brittle caking, which can not be considered as given in all boiler areas.

In the group of steam blowers, the pipe systems are cleaned with steam pressure. In this case, the steam jet exits from nozzles of a lance tube. This method is based on the cleaning effect by pressure and speed of the cleaning medium. However, the pressure and the velocity decrease with increasing distance from the exit point, so that the cleaning effect also decreases. In addition, varies depending on the location and design of the steam blower, the number of nozzles in the lance tube. By this constellation is not always given that the lane between the tubes in the feed / rotary motion is optimally achieved with the steam jet. The object of the present invention is to provide a device and a method for cleaning heating surfaces in a thermal installation, in which the disadvantages of the prior art mentioned do not occur.

The invention is based on the finding that this object can be achieved by providing a possibility to bring a cleaning device for dispensing cleaning medium in the immediate vicinity of the surface to be cleaned.

The object is achieved by a device having the features of claim 1 and by a method having the features of claim 12. Advantages and features that are described with respect to the device, apply - as applicable - according to the method and vice versa. Further embodiments of the invention will become apparent from the dependent subclaims.

According to a first aspect, the object is therefore achieved by a device for cleaning heating surfaces in a thermal system, in which at least one heating surface for heat recovery from the flue gas, which in the thermal

Implementation of a feedstock is created, is provided. The device is characterized in that at least one cleaning system is provided with at least one cleaning device for at least one of the heating surfaces, wherein the cleaning device of one of the side walls of a flue, in particular a boiler train, the thermal system in which the flue gas is guided in the Flue gas, in particular boiler train, is introduced and has a height which is less than an existing between heating surfaces, which belong to a heating unit, existing clear distance.

For the purposes of the invention is as a functional heating unit, for example, a superheater, evaporator, economizer, a heat trap, also referred to as a cold trap can be, and / or a pollutant trap called. These functional heating units may comprise one or more heating units, each of which is typically fed by a collector and, for example, represent tube bundles, a group of coiled coils or a multi-flow tube guide. Each heating unit comprises one or more heating elements. As a heating element in the context of this invention, in particular a pipe coil, tubes of a tube bundle, called pipes of a multi-flow pipe guide. The heating elements provide heating surfaces. Heating surfaces are smoke-side heating surfaces in the context of the invention, in particular the pipe surface of tubes of a tube bundle or of pipe coils. On the heating surfaces, the flue gas can give off heat. As a rule, the heating surfaces are the pipe surfaces of internally cooled pipes. In the case of the pollutant trap as a heating unit but this can also be designed so that no cooling is provided. In this case, the pollutant particles store at the pollutant trap in particular due to deflection of the flue gas stream, exposure of the tubes with electric current and / or the temperature of the tube, which is adjusted by cleaning or kept constant. Sidewalls in the context of the invention, are all boiler walls, which limits the boiler interior to the sides of the boiler to the environment. In particular, these are the left and right side wall, the front and back wall and possibly the funnels. The cleaning device, which is introduced into the flue, in particular boiler train, and whose height is according to the invention low, for example, has a round cross-section. The height of the cleaning device in this case corresponds to the diameter of the cleaning device. The cleaning device serves in particular for supplying cleaning medium, in particular liquid cleaning medium, to the at least one heating surface.

The heating surfaces, in particular the convective heating surfaces, such as the heating surfaces, that is, the tube surfaces, the superheater and the economizer, in part, the evaporator and so-called heat traps or a deposition surface, which is also referred to as pollutant trap are in thermal systems usually through Pipe systems of the heating units formed and the tubes, that is, the heating elements of the heating units are mainly at right angles to the flow direction of the flue gas. By introducing a cleaning device on a side wall of the flue, in particular boiler train, this can be in the immediate vicinity of the heating surface to be cleaned, ie tube surface, brought. This is not reliably possible with an introduction, for example through the boiler ceiling, since additional heating surfaces or pipes or entire functional heating units are optionally arranged above the heating surface to be cleaned and thus hinder the vertical access to the heating surface. Furthermore, in the lateral introduction of the

Cleaning device a boiler load reduction of the thermal system not necessary.

Due to the low construction of the cleaning device according to the invention at least in the area in which this is introduced into the flue, in particular boiler train, the cleaning device can also be brought close to individual heating surfaces and also between closely spaced heating surfaces, such as between tubes of a tube bundle. The height of the cleaning device or the diameter of the cleaning device can be at a clearance of the tubes of a tube bundle to each other by 110mm, for example in the range of 50mm to 100mm. A discharged via the cleaning device cleaning medium can thereby reach the reliable and targeted to be cleaned heating surface. By virtue of the small distance to the heating surface to be cleaned according to the invention, the cleaning medium can also reach the surface to be cleaned even with a small initial pressure.

In prior art cleaning devices, such as steam blowers, where high pressure cleaning media is used to remove deposits on heating surfaces, erosion of the surface of the heating surface may occur. In the invention possible low Pressure is not to be feared such a damage of the heating surface. Rather, a gentle cleaning of the heating surfaces can take place with the device according to the invention.

Preferably, the cleaning device has a height that is less than the clear distance between adjacent heating elements of a heating unit. If the heating unit represents, for example, a tube bundle, then the height of the cleaning device or its diameter is dimensioned such that it is smaller than the distance between two adjacent tubes of this tube bundle. Adjacent in this context means the arrangement of pipes without the presence of further pipes in the space between these pipes. In this respect, adjacent heating elements can also represent tubes of two heating units, which are arranged offset to one another.

In a further preferred embodiment, the cleaning device has a height that is less than the clear distance between adjacent heating surfaces of a heating element. In this case, for example, the cleaning device can be brought between the longitudinally extending pipe sections of a pipe coil, which run parallel to one another.

With the dimensioning of the cleaning device used according to the invention, this can thus be brought into the different areas of heating units, for example, between pipes of a tube bundle.

The introduction opening for the cleaning device is preferably in

Flue gas direction before and / or disposed between at least two heating surfaces. The introduction openings for the cleaning device can be arranged, for example, in front of the first row of tubes and / or between rows of tubes of a tube bundle and / or in front of the first longitudinally extending tube section of a tube coil and / or between tube sections of a tube coil extending in parallel. In particular, with the device according to the invention the From the flue gas streamed pipe surface, that is, the flue gas side heating surface of the pipe to be cleaned. By means of a suitable positioning, both a heating surface located in the direction of the flue gas upstream and / or downstream of the cleaning device and, if appropriate, laterally arranged heating surfaces can be cleaned with the cleaning device. Thus, a three-dimensional cleaning can take place around the cleaning device. On a flue, in particular boiler train, several introduction openings for cleaning devices and at the same time several cleaning devices can be provided.

The introduction opening for the cleaning device preferably has a device for closing the introduction opening. As a result, between cleaning cycles that are performed during operation of the thermal system, the side wall of the boiler train are closed.

According to one embodiment, the cleaning device is designed to be mobile and can be removed from the system. Removal from the plant in this context essentially means removal from the boiler room. If the cleaning device designed mobile, it can at different times in different places in boiler trains but also on other lines or

Plants are used. The provision of separate cleaning devices for different heating surfaces is not required, so that the manufacturing and operating costs of the system can be reduced.

The cleaning device can be operated manually, semi-automatically or automatically.

The cleaning device preferably has at least one outlet for a cleaning medium. In the case of longitudinally extending cleaning devices, such as lances, a discharge from the cleaning medium to heating surfaces which are adjacent to the cleaning device, in particular in FIG Flow direction of the flue gas before and / or behind the cleaning device. In addition, pipe coverings can be removed through an outlet of cleaning medium in the feed direction of the cleaning device.

According to a further embodiment, the cleaning system comprises

Cleaning device a lance. At this lance an outlet for the cleaning medium can be provided, for example, in the area of the lance tip. But it is also possible to provide distributed over the length of the lance at least one outlet for the cleaning medium. Outlets may be outlet ports or other suitable outlet devices. The geometry of the outlets can be chosen so that they deliver, for example, a stream of cleaning medium upwards and downwards. But it is also possible to use nozzles in which over the entire circumference of the lance cleaning medium is discharged and thus all the heating surfaces located around the lance are subjected to the cleaning medium. The geometry of the outlets can be used to influence their effective radius. Since the cleaning device has a low height and is introduced via the side wall of the flue gas pass, in particular boiler pass, a targeted cleaning of individual heating surfaces can take place in different levels. For example, the third or fourth row of a tube bundle, which forms a heating unit, can be cleaned reliably, which is not possible with cleaning devices which operate at high pressure. On the one hand, because of the high pressure of the cleaning medium, the cleaning devices of the prior art usually have a large height or have a larger diameter and thus are not introduced into the small distances between heating elements of a heating unit, for example, between pipes or rows of tubes of a tube bundle can. On the other hand, these cleaning devices must have a greater distance to the heating surface due to the applied by this larger pressure. In impulse-powered cleaning devices of the prior art, the pulse is also after a few rows of tubes a

Used tube bundle or a heating unit. This will do that Removal of the linings of underlying rows of pipes, greatly attenuated due to the required higher pressure. An even higher pressure would damage the first rows of tubes.

Due to the low pressure with which according to the present invention, the cleaning medium must be discharged from the cleaning device, a low overall height is possible in the inventive cleaning device. This low height or this small diameter in turn allows the introduction of the cleaning device at any point, especially in tube bundles, that is, between pipes that form a tube bundle.

The cleaning system may according to the invention have a control and in the control end positions for an automatic operation of the cleaning device can be deposited. The end positions can be realized in the control by limit switches. In a horizontal movement of the cleaning device, the end positions usually correspond approximately to the positions of the side walls.

Horizontal in the sense of the invention, an imaginary plane or distance is perpendicular to the vertical, which may differ in space with a given angle from this imaginary plane, but without reaching the vertical. Horizontal in the sense of the invention is thus any direction that has a horizontal direction component that is not equal to zero.

The cleaning system may additionally or alternatively have a control that serves for pressure monitoring and / or flow control for the cleaning medium. As a result, the cleaning device is more flexible. In particular, the pressure and the amount of control can be adjusted depending on the geometry of the outlet for the cleaning medium and the geometric and thermal conditions or pollution and flow conditions in the vicinity of the cleaning device. The entry depth of the cleaning device in the flue, in particular boiler train, can be controlled via the end positions of the cleaning device.

The cleaning device may be aligned transversely or parallel to the longitudinal axis of the surface to be cleaned. As a longitudinal axis in this case the longitudinal extent of the surface is referred to. In a coil, this is particularly the axis of the straight pipe sections of the coil, which are usually parallel to each other.

According to a further aspect, the present invention relates to a method for cleaning a heating surface in a thermal installation in which at least one heating surface is provided for recovering heat from the flue gas which is produced in the installation. The method is characterized in that the temperature of a coating formed on the heating surface is lowered by applying a cleaning medium. The covering on the heating surface may be a continuous covering but also a local deposition. The temperature change of the lining changes the physical properties of the lining, in particular its extent. The lining will therefore contract and thus detach from the heating surface. By applying the cleaning medium thus takes place a mechanical relaxation of the coating, which leads to the falling of the coating from the heating surface. This cleaning method is particularly suitable for the cleaning of convective heating surfaces in a thermal plant, since there usually allow the temperature conditions such a detachment.

According to one embodiment, the cleaning medium is introduced via a cleaning device via one of the side walls of a flue, in particular boiler flue, in a boiler train of the thermal system and applied under low pressure to the at least one heating surface. By the introduction of the cleaning device via one of the side walls of a flue, in particular boiler train, takes place, this can be brought into the vicinity of the heating surfaces to be cleaned. This is especially true for the convective boiler trains, in which the heating surfaces are usually provided in heating units in the form of horizontally or vertically extending tube bundles. Due to the proximity to the heating surface to be cleaned a very placed cleaning effect can be generated. Through this targeted cleaning and the amount of cleaning medium required can be minimized. This is advantageous because the temperature of the flue gas is lower in the heating surfaces in the convective boiler trains compared to the upstream Strahlungskesselzügen. Due to the minimized amount of cleaning medium thus a sufficient cleaning of the heating surfaces is possible without significantly affecting the overall process.

By bringing the cleaning device in the vicinity of the surface to be cleaned, according to the invention also a low pressure for the

Cleaning medium can be selected. This low pressure is advantageous because it can be realized even with small dimensions, in particular at a low height of the cleaning device. The cleaning device can thus be brought very close to a heating surface and optionally even between heating surfaces, for example, in a tube bundle introduced.

In addition, at a low pressure, even at a small distance from the surface to be cleaned damage to the heating surface, for example by erosion and by the impulse of the impingement of the cleaning medium is not to be feared.

Preferably, the cleaning medium, which is introduced via the cleaning device, has a temperature which is lower than the temperature of the coverings on the surface to be cleaned. In particular, the temperature is lower than the temperature that the pads on the outside, that is, the side facing away from the heating surface or the tube surface. These Temperature is usually higher than the temperature of the heating surface itself. By applying a relatively cooler cleaning medium on the heating surface and in particular on the coating thereon, the heat can be removed from the coating, whereby the coating separates from the heating surface. The temperature difference between the coating and the cleaning medium when hitting the coating is, for example, greater than 100 K.

The cleaning effect is achieved by applying the cleaning medium, which is preferably a liquid, to the coverings and / or deposits. Due to the Leidenfrost ^' cal phenomenon forms around the liquid droplets introduced into the flue gas stream a steam envelope. Gases or vapors are poor heat conductors, so that the liquid drop does not spontaneously evaporate despite the high ambient temperatures, even greater than 600 ⁰ C. As a result of this effect, the liquid droplet, despite its low velocity, reaches the deposition surfaces or the adhering deposits and / or deposits. The deposits and / or deposits are cooled, inter alia, by evaporation of the liquid. This results in embrittlement and stress in the linings and / or deposits, which they are solved.

The lower temperature of the cleaning medium when hitting the covering can also be realized in the method according to the invention, since the cleaning medium is discharged in the vicinity of the heating surface to be cleaned from the cleaning device and a strong heating of the cleaning medium is not to be feared in the rule.

The cleaning medium can, as already mentioned above, be dispensed in different directions from the cleaning device. According to a preferred embodiment, the cleaning medium is discharged from the cleaning device in another vertical direction.

In particular, the cleaning device is discharged in a direction that relative to the surface to be cleaned has a vertical directional component, which is not equal to zero. This results, among other things, in a cleaning plane perpendicular to the preferred orientation or feed direction of the cleaning device. By moving the cleaning device in the horizontal direction creates a cleaning plane, which is shifted and thus reaches a significant proportion of the surface of the heating surface.

In the method according to the invention, the cleaning medium may be water. The advantage of using water is that stress on the overall system is not expected, and this cleaning medium causes low procurement costs. By using a liquid cleaning medium and in particular of water, in the method according to the invention, the covering on the heating surface can be wetted. In addition, a liquid, such as water, increases the weight of the lining and thus promotes detachment from the heating surface.

The cleaning medium is preferably released from the cleaning device at a low pressure, that is, a low pre-pressure, of less than 10 bar, preferably less than 6 bar. The pressure is controlled so that it is adjusted depending on the distance to the heating surfaces to be cleaned. The pressure is set to a value that ensures that the cleaning medium impinges on the heating surface. However, a considerable impulse when striking should be avoided. Depending on the orientation of the outlet or outlets on the cleaning device, the cleaning medium can also be dispensed without pressure from the cleaning device. In this case, the cleaning medium is transported only to the outlet and can reach there by gravity to a heating surface located below the cleaning device. In this case, the heating surface is sprinkled with the cleaning medium. The cleaning device is preferably moved during the cleaning of the heating surface in the horizontal direction. Even if only a single outlet for the cleaning medium, for example at the lance tip, is provided on the cleaning device, a heating surface can be cleaned substantially over its entire length when guiding the cleaning device parallel to the longitudinal axis of the heating surface, in particular of tubes in vertically guided cleaning devices and horizontal heating surfaces is not possible or only with great effort.

However, it is also possible to guide the cleaning device perpendicular to the longitudinal axis of the heating surface. In this case, subregions of adjacent heating surfaces, in particular of adjacent tubes, are treated with cleaning agent via the advance of the cleaning device and thus cleaned.

The cleaning is preferably carried out during the operation of the thermal system. By prevailing during operation of the system temperature conditions, a detachment of the pads from the heating surfaces can be ensured by peeling. In particular, heat can be removed from the covering under these temperature conditions in a simple manner and thus the detachment of the covering can be achieved. In addition, the cleaning method according to the invention on the intended operation of the boiler has only minor side effects, so that a largely undisturbed operation is guaranteed.

The cleaning medium is preferably discharged with the removed contaminants via the discharge device or with the flue gas. This is possible in the method according to the invention, since the amount of cleaning medium due to the proximity of the cleaning device to the surface to be cleaned and the leading to the detachment of the coating conditions, in particular the temperature reduction of the coating can be kept low. Adhesion of moist dust in the discharge device, in particular a discharge hopper is therefore unlikely to be expected. With the present invention, thus a reliable cleaning of the heating surfaces, in particular the surfaces of pipe coils and surfaces of pipes of a tube bundle can be achieved and thereby on the one hand, an optimal heat transfer to the heating surfaces are guaranteed. Furthermore, closing the flue gas path between the pipe systems can be prevented by the cleaning, whereby an increase in the pressure loss in the boiler interior over the travel time is reduced. Finally, the removal of accumulating on the pipes pollutants attack the surface, for example by corrosion, can be avoided.

The invention will be explained again below with reference to the accompanying drawings which show possible embodiments of the present invention. In particular show:

Figure 1: a schematic representation of a waste incineration boiler with vertical boiler trains; Figure 2: a schematic block diagram of an embodiment of a

Cleaning system; Figure 3: a schematic representation of a waste incineration boiler with horizontal boiler trains; Figure 4: a schematic representation of an embodiment of

heating surfaces;

Figure 5: a photograph of a crude pipe system; Figure 6: a photograph of a pipe system cleaned during operation; and

Figure 7: a schematic sectional view of the position of a

Cleaning device between heating elements of a

Heating unit.

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

The thermal plant, which is a waste incineration plant in FIG. 1, has a furnace 15 and four vertical boiler passes 16, 17, 18 and 19. 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 lines 16, 17 close in flue gas direction R boiler trains 18, 19 with convective functional heating units. In the illustrated embodiment, a heat trap 21 and four superheaters 22.1 to 22.4 are arranged in the third boiler train 18. In the subsequent fourth boiler train 19 four economizers 23.1 to 23.4 are arranged. These functional heating units, which have heating units with a number of convective heating surfaces, are designed as piping systems. The structure of the pipe systems, each of which is a heating unit, is shown schematically in Figure 4, the heating surfaces being formed by tubes.

The combustion of fuels in the combustion chamber 15 produces, inter alia, gaseous, liquid and solid pollutants. These are carried in the flue gas stream R. Despite a partial, passive deposition of pollutants in the vertical trains 16; 17, the convective heating surfaces of the functional heating units (heat trap [21], superheater [22.1 to 22.4], economiser [23.1 to 23.3]) are exposed to pollutants. The formed as a pipe system convective heating surfaces of the functional heating units 21; 22; 23 are in the flue gas flow R (see Fig. 4) in the following boiler trains 18; 19. The temperature range of the flue gas in the region of entry into the superheater is, for example, depending on the travel time 550 ⁰ C to 650 ⁰ C. At these temperatures, for example, pollutant-bearing dusts of some solid, pasty and / or liquid consistency and tend to stick , By adhering the dusts to the pipe systems of the heating units, the heat utilization is reduced and the Flue gas paths are narrowed. Furthermore, the dusts and gases contribute to the corrosion of the pipes.

To clean these surfaces, a cleaning system shown schematically in Figure 2 can be used. The cleaning device here comprises as a cleaning device a substantially horizontally guided lance 1 with specially constructed nozzle 2. The lance 1 is introduced through the boiler wall in the boiler interior. The geometry of the lance 1 is selected so that the outlet openings 2 at the points to be cleaned in the space between the pipe systems [Fig. 4], i. between the individual tubes of the heating unit, for example, between the tubes of a Mehrflutigen pipe system, can get. The lance 1 is by means of a drive 4 in the space between the pipe systems [Fig. 4].

To automate the process, for example, two limit switches 5 and 6 can switch the drive 4 in a reverse or in the standstill. The supply of the lance 1 with the cleaning medium via a supply, such as a flexible hose 3. A control roller 7 gives a pulse to open (close) of the solenoid valve 8 after the lance 1 has reached the boiler inside (-Outside). Thus, for example, after entering the outlet openings 2 in the boiler interior 16 to 19 via a control roller 7, a pulse for opening the solenoid valve 8 are given. By opening the solenoid valve 8, a defined amount of the cleaning medium under a defined pressure is largely uniformly applied 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, especially if the cleaning trips are repeated more often and between the repetitions of the boiler can regenerate in terms of temperature. A boiler load reduction during cleaning is not necessary. The detached dusts and coverings can be discharged via the hopper 20 and the existing Kesselaustragsysteme (not shown) easily. 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.

The cleaning effect is achieved by a stream of cleaning medium drops. This stream acts in the direction of the pipe system, that is, on the individual pipes, with a profile depending on the geometric and procedural conditions. The effective area can be adjusted from the parameters cleaning medium pressure and nozzle geometry. Due to the given dimensions, the system can work with a low cleaning medium pressure. This blow damage to the heating surfaces can be avoided. The cleaning effect due to the above-described relationships and the resulting detachment of the coverings can therefore be used particularly efficiently in the method according to the invention.

The arrangements of the cleaning device, in particular the lance 1, in the boiler trains 16 to 19 during cleaning is indicated schematically in Figures 1 and 4. The lances protrude into the image plane and are located at the clear distance A between the tubes of the heating units of the functional heating units 21 to 23.

Figure 3 shows another embodiment of a thermal plant in which the boiler trains are arranged horizontally. Also in this system, the lances 1 protrude into the image plane and thus extend between the tubes of the heating units 21 to 23.

In the figure 4, the heating units 21 and 22.1 are shown schematically. Here, in each case a heating element of the respective heating units 21, 22.1 is shown. The heating units represent pipe coils here. Further raw coils are arranged in front of and behind the plane of the drawing. The cleaning device 1 or lance 1 is shown in Figure 4 in an orientation in which this protrudes into the image plane. However, it is also possible that the lance 1 is guided in the image plane, that is, along the parallel pipe sections of the coils.

FIG. 7 shows a schematic illustration of heating elements in the form of tubes, for example a tube bundle, and a cleaning device 1 introduced therein in a vertical sectional view. The illustrated arrangement may be, for example, the functional heating unit of the superheater 22.1. As can be seen from FIG. 7, the lance 1 is arranged between four tubes of the superheater pact 22.1 and can thus clean all four tubes. In the illustrated embodiment, the diameter of the lance is less than the clear distance A between the tubes of the heating element 25 and also as the clear distance A between adjacently offset from each other arranged tubes of two adjacent heating elements 25th

Finally, in Figures 5 and 6, designed as a pipe system heating surface is shown with adhering coatings. As can be seen from these photographs are the coverings for cleaning in the area in which the

Cleaning device was introduced into the boiler room, significantly reduced. On the boiler wall, Figure 6 shows the inlet opening for the cleaning device. Furthermore, in FIG. 6, the pipes of the pipe system can be seen on the left side, whereas in the case of an unpurified pipe system in FIG. 5, the pipes are not visible.

The invention is not limited to the illustrated embodiment. In particular, it is also possible to provide more than the cleaning level shown in the figures. This can be realized by the provision of additional outlet openings on the lance. The selection of the parameters

Quantity and form of the cleaning medium is preferably adjusted so that it comes to a cleaning effect without damage to the pipe surface by, for example, abrasion. The outlet of the cleaning medium is preferably carried out via one or more nozzles on a lance. However, other outlet devices may be used. Preferably, the application of the cleaning medium takes place symmetrically, so as to cause no reaction forces on the lance. The cleaning device preferably has a low design and can thus reach between the tubes of the pipe systems, that is, the heating units. The exit angle of the cleaning medium can be adapted to the requirements of geometry of the pipe systems and process engineering conditions. The exit angle is usually determined by the outlets and their orientation. But it is also possible to use other devices, such as obstacles, in the form of baffles to direct the cleaning medium flow in the desired direction.

With the present invention, the heating surfaces, in particular the

Pipe systems of the heating units are cleaned so well that can preferentially deposit new solid or condensable pollutants, which can then be replaced in a further purification step. Thus, in addition to the improvement of the cleaning of the heating surfaces also a deposition of pollutants on the heating surfaces and a targeted discharge of pollutants from the boiler can be done.

The invention allows cleaning during boiler operation. In addition, cleaning can be carried out without lowering the boiler load, and the removed dusts and deposits can generally reach the boiler ash discharge systems in a dry state.

With the invention, it is thus possible to provide a method and an apparatus, wherein the pipe systems, in particular of functional heating units, such as superheaters, economizers and evaporators, which can be insufficiently cleaned according to the prior art, freed during operation of coverings can be and thus optimizes the heat transfer, a narrowing of the flue gas path avoided and / or pollutants can be removed from the pipes, in order to ultimately increase the plant operating times.

The invention has been described essentially with reference to a combustion plant, in particular a waste incineration plant. The invention is not limited to this type of thermal systems. It is also within the scope of the invention to use the cleaning device in another thermal installation, such as a cement making apparatus, and to carry out the method according to the invention in this annex. If the thermal installation is a plant different from a waste incineration plant, the boiler flues mentioned in the description are to be understood as the flues of the thermal plant. The other features and advantages of the invention, which have been described with respect to the waste incineration plant apply to other thermal systems - as applicable - accordingly.

LIST OF REFERENCE NUMBERS

1 lance

2 nozzles

3 Flexible connection

4 drive

5 limit switches

6 limit switches

7 tax role

8 solenoid valve

9 Volume control

10 quantity measurement

11 pressure monitors

12 control

13 slides

14 barrier

15 firebox

16 First boiler train

17 Second boiler train

18 Third boiler train

19 Fourth boiler train

20 funnels

21 heat traps

22 superheaters

22. 1 superheater package 1

22. 2 superheater package 2

22. 3 superheater package 3

22. 4 superheater package 4

23 economiser

23. 1 Economiser 1

23. 2 Economiser 2

23. 3 Economiser 3

23. 4 Economiser 4

24 heating element

25 heating unit

Claims

claims

1. A device for cleaning heating surfaces in a thermal plant, in which at least one heating surface for heat recovery from the flue gas (R), which is formed during the thermal conversion of a feedstock, is provided, characterized in that at least one cleaning system with a cleaning device (1 ) is provided for at least one of the heating surfaces, wherein the cleaning device (1) of one of the side walls of a flue gas duct (16, 17, 18, 19) of the thermal system, in which the

Flue gas (R) is introduced into the flue gas duct (16, 17, 18, 19) and has a height which is lower than a between heating surfaces belonging to a heating unit (21, 22, 23, 25), existing lights distance (A).

2. Apparatus according to claim 1, characterized in that the

Cleaning device (1) has a height which is less than the clear distance between adjacent heating elements (24) of a heating unit (21, 22, 23, 25).

3. Device according to one of claims 1 or 2, characterized in that the cleaning device (1) has a height which is less than the clear distance between adjacent heating surfaces of a heating element (24).

4. Device according to one of claims 1 to 3, characterized in that the cleaning device (1) preferably in the flue gas direction (R) before and / or between at least two heating surfaces (21, 22, 23).

5. Device according to one of claims 1 to 4, characterized in that the introduction opening for the cleaning device (1) comprises means for closing the insertion opening.

6. Device according to one of claims 1 to 5, characterized in that the cleaning device (1) is designed to be mobile and thus can be removed from the thermal system.

7. Device according to one of the claims 1 to 6, characterized in that the cleaning device (1) is operated manually, semi-automatically or automatically.

8. Device according to one of claims 1 to 7, characterized in that the cleaning system as a cleaning device comprises a lance (1) and over the length of the lance (1) at least one outlet (2) are provided.

9. Device according to one of claims 1 to 8, characterized in that it comprises a controller (12) and in the controller (12) end positions for an automatic operation of the cleaning device (1) are stored.

10. Device according to one of claims 1 to 9, characterized in that it has a controller (12) and the control for pressure monitoring (11) and / or flow control (9) for the cleaning medium is used.

11.Vorrichtung according to one of claims 1 to 10, characterized in that the entry depth of the cleaning device (1) is regulated by end positions.

12. A method for cleaning heating surfaces (21, 22, 23) in a thermal system, in which at least one heating surface (21, 22, 23) for heat recovery from the flue gas (R), which is formed in the system, is provided by characterized in that the temperature of a coating formed on the heating surface (21, 22, 23) is lowered by applying a cleaning medium.

13. The method according to claim 12, characterized in that a

Cleaning device (1) via one of the side walls of a flue gas duct (16, 17, 18, 19) in a flue (16, 17, 18, 19) of the thermal system is introduced and via this cleaning device (1) a cleaning medium under low pressure on the at least one heating surface

(21, 22, 23) is applied.

H.Verfahren according to claim 12, characterized in that the

Cleaning medium with a temperature on the heating surface (21, 22, 23) is applied, which is lower than the temperature of the deposits on the surface to be cleaned.

15. The method according to claim 12 to 14, characterized in that the cleaning medium from the cleaning device (1) is discharged in another vertical direction.

16. The method according to any one of claims 12 to 15, characterized in that the cleaning device (1) is preferably introduced before and / or between at least two heating surfaces (21, 22, 23).

17. The method according to any one of claims 12 to 16, characterized in that the cleaning medium is water.

18. The method according to any one of claims 12 to 17, characterized in that the cleaning medium at a pressure of less than 10 bar, preferably less than 6 bar, from the cleaning device (1) is discharged.

19. The method according to any one of claims 12 to 18, characterized in that the cleaning device (1) during the cleaning of the heating surface (21,

22, 23) is moved in the horizontal direction.

20. The method according to any one of claims 12 to 19, characterized in that the cleaning takes place during the operation of the thermal plant.

21. The method according to any one of claims 12 to 20, characterized in that the cleaning medium is discharged with the removed contaminants on the discharge or with the flue gas.