Method for cleaning an air preheater of a combustion boiler, use of a soot blower for cleaning an air preheater and soot blower for cleaning an air preheater

Abstract

The invention relates to a method for cleaning an air preheater (1) of a combustion boiler (2), having at least the following steps: a) providing a soot blower (3); and b) cleaning the air preheater (1) with the aid of the soot blower (3), wherein a cleaning gas having a gas outlet temperature of at least 180°C is discharged using the soot blower (3). The invention also relates to a use of a soot blower (3) for cleaning an air preheater (1) of a combustion boiler (2). The invention further relates to a soot blower (3) for cleaning an air preheater (1) of a combustion boiler (2).

Description

[0001] Method for cleaning an air preheater of a combustion boiler, use of a soot blower for cleaning an air preheater and soot blower for cleaning an air preheater

[0002] The present invention relates to a method for cleaning an air preheater of a combustion boiler, the use of a soot blower for cleaning an air preheater, and a soot blower for cleaning an air preheater. The combustion boiler can, in particular, be part of a power plant for generating thermal energy, which can be converted into electrical energy by the power plant. The air preheater can be a gas-to-gas heater.

[0003] In the combustion boilers of a power plant, the combustion of fuels, waste, and the like produces flue gas. Due to its temperature, this flue gas is suitable for recovering its thermal energy through subsequent contact with heat exchangers and / or heat transfer by radiation and / or convection. The combustion boiler can, in particular, be a steam generation plant or part thereof. During combustion, in addition to ash, soot, dust, etc., aggressive gases, metal vapors, and the like may also be produced. These components contained in the flue gas are deposited during operation, especially on the walls and internal components of the combustion boiler or steam generation plant through which the flue gas passes.As a result of the increasing accumulation of such substances, the heat exchange between the flue gas and the heat exchangers decreases, thereby reducing the efficiency of the combustion boiler or steam generation plant. For this reason, it is known to clean the surfaces inside the combustion boiler or steam generation plant as needed, removing the adhering contaminants, slag, etc. To improve thermal efficiency, power plants can be equipped with air preheaters that preheat the combustion air supplied to the combustion boiler by utilizing the thermal energy contained in the flue gas. The thermal energy transferred to the combustion air no longer needs to be provided by the fuel, thus increasing the thermal efficiency of the combustion process.

[0004] Nitrogen oxides (NOx) in flue gas can be reduced using a selective catalytic reduction (SCR) process. In the SCR process, ammonia (NH3) is used as a reducing agent to convert NOx into nitrogen (N2) and water (H2O). If too much ammonia is added or the process is not optimally adjusted, excess ammonia (so-called ammonia slip) can be carried along with the flue gas. Sulfur oxides (SO2 and SO3) are also frequently present in the flue gas. These are produced during the combustion of sulfur-containing fuels. At certain temperatures (typically between 200 °C and 300 °C), the ammonia can react with sulfur trioxide (SO3) to form ammonium hydrogen sulfate (NH4HSO4), which can deposit in the air preheater. The ammonium hydrogen sulfate can reduce the efficiency of the air preheater, clog it, and / or promote corrosion.

[0005] The air preheater therefore requires regular manual cleaning with high-pressure water, which is labor-intensive and can damage the preheater. Alternatively, attempts were made to clean the preheater with steam, which is blown into the preheater using a soot blower (e.g., at approximately 1 MPa [megapascal]) through nozzles with a diameter of up to 6 mm. However, this method does not achieve satisfactory cleaning results.

[0006] The object of the invention is therefore to at least partially solve the problems described with reference to the prior art and, in particular, to provide a method for cleaning an air preheater of a combustion boiler, with which air preheaters can be reliably cleaned and damage to the air preheaters can be avoided. Furthermore, the use of a soot blower for cleaning an air preheater of a combustion boiler is proposed, with which air preheaters can be reliably cleaned and damage to the air preheaters can be avoided. In addition, a soot blower is proposed with which air preheaters can be reliably cleaned and damage to the air preheaters can be avoided.

[0007] These problems are solved by a method, an application, and a soot blower according to the features of the independent claims. Further advantageous embodiments of the method and the soot blower are specified in the dependent claims. It should be noted that the features listed individually in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0008] This is achieved by a method for cleaning an air preheater of a combustion boiler, which includes at least the following steps: a) providing a soot blower; and b) cleaning the air preheater using the soot blower, wherein a cleaning gas with a gas outlet temperature of at least 180 °C is discharged with the soot blower.

[0009] The combustion boiler can be a component of a power plant. The power plant generates electricity by converting a fuel into electrical energy. This fuel can be, for example, a fossil fuel, coal, natural gas, oil, biomass, biogas, and / or waste. The fuel can be supplied to the combustion boiler via a fuel feed and / or combustible within the combustion chamber of the boiler. Combustion of the fuel produces flue gas, which can have a flue gas temperature of up to 1,800 °C. Combustion air can be supplied to the combustion chamber for the combustion of the fuel. This combustion air can be fresh air, ambient air, and / or filtered air, for example, from the surrounding area of ​​the power plant. The combustion air can be supplied to the combustion boiler via at least one air supply duct.Combustion air can be supplied to the combustion chamber via at least one air nozzle, for example in a boiler wall of the combustion boiler.

[0010] The combustion boiler, power plant, or air supply duct may include an air preheater. The air preheater preheats the combustion air by utilizing the thermal energy of the flue gas. The flue gas is supplied to the air preheater from the combustion boiler or combustion chamber, in particular via at least one flue gas passage. The air preheater may be a rotary heat exchanger. The air preheater may have a housing and / or a rotor. The housing may have inlet and outlet channels for the combustion air and / or the flue gas. The rotor may be located within the housing and / or rotate around an axis of rotation during operation of the air preheater. The axis of rotation may, for example, be (essentially) vertical. The rotor may have a diameter of, for example, 5,000 mm to 20,000 mm (particularly perpendicular to the axis of rotation) and / or a length of, for example, 1,000 mm to 4 mm (particularly parallel to the axis of rotation).The air preheater or rotor may have a diameter of 000 mm. It may include at least one heat exchanger element. The rotor and / or the heat exchanger element may have a plurality of flow channels for the combustion air and / or the flue gas. The rotor and / or the heat exchanger element may be designed as a honeycomb structure. The flow channels may be formed and / or bounded by a plurality of metal plates, metal sheets, and / or metal tubes. At least some of the metal plates and / or metal sheets may be at least partially corrugated. The air preheater, the rotor, and / or the flow channels may be open to flue gas flow in a first sector of the air preheater and open to combustion air flow in a second sector of the air preheater, for example, according to the counterflow principle.The rotor can rotate, particularly continuously, around its axis of rotation and / or relative to the housing, through the first and second sectors of the air preheater. During this process, the flue gas heats the portion of the rotor located in the first sector of the air preheater. The heated portion of the rotor then rotates into the second sector of the air preheater and heats the combustion air there.

[0011] In step a), at least one soot blower is provided. The soot blower can be located on a combustion air supply side or on a flue gas exhaust side of the rotor (also referred to as the cold end of the rotor or air preheater) and / or on a combustion air exhaust side or on a flue gas supply side of the rotor (also referred to as the hot end of the rotor or air preheater). The soot blower can have at least one lance tube with at least one nozzle. The nozzle can be located in a circumferential surface of the lance tube. The lance tube can be a so-called "rake" tube. The nozzle can be designed as an opening or bore. The soot blower can be located outside the air preheater or housing. The lance tube of the soot blower can be at least partially inserted into the air preheater or rotor for cleaning purposes.The air preheater or the housing can be moved into the housing. For this purpose, the air preheater or the housing can have at least one opening for the lance tube, which can be closed.

[0012] In step b), the air preheater or rotor is cleaned using the soot blower. The soot blower discharges a cleaning gas with a gas outlet temperature of at least 180 °C, preferably at least 200 °C. The cleaning gas is, in particular, (superheated) water vapor, which is significantly more superheated than usual. The cleaning gas is supplied to the soot blower or lance tube from a cleaning gas source, for example, via a supply line. The gas outlet temperature is, in particular, the temperature at which the cleaning gas leaves the at least one nozzle. During cleaning of the air preheater, the at least one nozzle can be located at a distance from the rotor of, for example, a maximum of 500 mm (especially parallel to the axis of rotation). During cleaning of the air preheater, the cleaning gas is directed, in particular, into the flow channels of the air preheater.of the rotor and / or through the flow channels of the air preheater or the rotor. Due to the high gas outlet temperature of the cleaning gas, contaminants in the air preheater or the rotor, especially ammonium hydrogen sulfate (NH4HSO4) (also known as ammonium bisulfate or ABS), are melted and / or decomposed and thus more easily detached from the air preheater or the rotor, particularly by the injection of superheated cleaning gas or steam from the soot blower and / or simply by a carryover effect of the flue gas.

[0013] The characteristic that the cleaning gas is discharged from the soot blower at a gas outlet temperature of at least 180 °C can refer specifically to the temperature at the outlet point of the cleaning gas at the nozzle, i.e., specifically where the cleaning gas (subsequently) effectively impacts the contaminated surfaces of the air preheater. The gas outlet temperature of at least 180 °C can be understood, in particular, as a locally effective thermal energy input at which the decomposition or conversion temperature required for certain deposits, such as ammonium-based compounds (e.g., ammonium hydrogen sulfate, ABS), is reliably exceeded.In this context, it is important to emphasize that the commonly used term "superheated steam" does not correspond to the characteristic of a gas outlet temperature of at least 180 °C and typically refers to steam generated above the saturation temperature of a given pressure, for example, in the range of 120 °C to 160 °C. However, such temperatures do not guarantee that the temperature at the point of action—i.e., at the nozzle of the soot blower or at the contaminants on the air preheater—is actually > 180 °C, especially not in the case of longer pipe runs, pressure losses, heat radiation, or throttling within the system. The gas outlet temperature of at least 180 °C is specifically chosen to achieve a thermally induced cleaning effect, particularly the thermal decomposition of sticky or chemically stable deposits in the air preheater, without requiring high mechanical cleaning impulses.Furthermore, a specific combination of gas outlet temperature and a defined nozzle geometry profile can be selected. Such a targeted selection creates a technical synergy effect: The hot cleaning gas can penetrate deep into the heat exchanger elements with low pressure but sufficient momentum and act in a targeted manner, thereby effectively removing even stubborn deposits.

[0014] Unlike conventional methods, the proposed method for cleaning stubborn deposits does not require an increase in cleaning pressure; instead, it raises the gas outlet temperature of the cleaning gas. Previously, cleaning was performed with a gas outlet temperature as close as possible to, or slightly above, the saturated steam temperature of 100 °C, because the cost of the cleaning gas increases with its outlet temperature. Furthermore, a high-quality cleaning gas source providing the necessary temperature is not readily available for cleaning or soot blowing purposes. However, it has been recognized that cleaning with a significantly higher gas outlet temperature is advantageous despite the higher cost of the cleaning gas, because it reduces cleaning time and causes less wear on the air preheater and rotor.Furthermore, cleaning can be carried out with very dry steam, which prevents the solidification of impurities, especially (powdered) ammonium hydrogen sulfate (NH4HSO4) or ammonium bisulfate.

[0015] In step b) contaminants of the air preheater (1) can be vaporized, melted and / or decomposed and the contaminants subsequently removed at least partially by the cleaning gas, flue gas and / or combustion air.

[0016] In step b), the gas outlet temperature can be 180 °C to 320 °C, preferably 200 °C to 320 °C. In particular, the cleaning gas can be discharged from the soot blower at an outlet temperature of 180 °C to 320 °C, preferably 200 °C to 320 °C, and most preferably 225 °C to 255 °C or 290 °C to 320 °C. A significant improvement in the cleaning effect can be achieved, especially at an outlet temperature of 290 °C to 320 °C.

[0017] The cleaning gas can be supplied to the soot blower at a gas inlet temperature of at least 400 °C, preferably at least 480 °C. The gas inlet temperature of the cleaning gas can be the temperature at which the cleaning gas flows into a cleaning inlet of the soot blower or the temperature at which the cleaning gas is located at the valve or inlet valve of the soot blower.

[0018] The gas inlet temperature can be 400 °C to 650 °C, preferably 480 °C to 610 °C.

[0019] The cleaning gas can be supplied to the soot blower at a gas inlet pressure of at least 1.2 MPa, preferably at least 2.5 MPa. The gas inlet pressure of the cleaning gas can be the pressure at which the cleaning gas flows into the cleaning gas inlet of the soot blower or the pressure at which the cleaning gas is present at the valve or inlet valve of the soot blower.

[0020] The gas inlet pressure can be 1.2 MPa to 7 MPa, preferably 2.5 MPa to 7 MPa.

[0021] The cleaning gas can be discharged through at least one nozzle having a diameter of at least 8 mm, preferably at least 11 mm. This ensures a sufficiently long cleaning range for the cleaning gas. When cleaning the air preheater in step b), the at least one nozzle can be oriented towards the axis of rotation and / or towards the flow channels. The soot blower or lance tube can have a plurality or multiple nozzles.

[0022] The diameter of the at least one nozzle can be 8 mm to 30 mm, preferably 11 mm to 30 mm, and particularly preferably 11.5 mm to 16 mm. The cleaning gas can be discharged through at least one nozzle, which, according to step b), is pivoted by 30° to 150°, preferably 80° to 100°, and particularly preferably (essentially) 90°. According to step b), the at least one nozzle is pivoted, in particular, about a longitudinal axis of the lance tube. For this purpose, the lance tube or an outer tube of the lance tube can be rotated about the longitudinal axis of the lance tube. By pivoting the at least one nozzle according to step b), fouling of the at least one nozzle during operation of the air preheater can be avoided or reduced, especially when the soot blower is in a detent position.

[0023] The cleaning gas can be discharged at a gas outlet pressure of 0.2 MPa to 0.8 MPa. This gas outlet pressure is the pressure at which the cleaning gas leaves at least one nozzle. The gas inlet pressure can be reduced, at least partially, to the gas outlet pressure by a throttle on the soot blower and / or by pressure losses within the soot blower. The low gas outlet pressure prevents damage to the air preheater or the rotor and, more importantly, ensures a higher gas outlet temperature of the cleaning gas (due to its inherent thermal properties).

[0024] Following a further aspect, the use of a soot blower for cleaning an air preheater of a combustion boiler is proposed, wherein the soot blower releases a cleaning gas with a gas outlet temperature of at least 180 °C and wherein the soot blower has at least the following features:

[0025] - a valve for a cleaning gas; and

[0026] - a lance tube with at least one nozzle for delivering the cleaning gas, wherein the nozzle has a diameter of at least 8 mm, preferably at least 11 mm.

[0027] The soot blower is used in particular for carrying out the process described herein. The soot blower is specifically designed and configured for carrying out the process described herein. The soot blower has a valve for the cleaning gas. This valve can be an inlet valve of the soot blower. The valve allows control of the discharge of the cleaning gas. The valve can be a shut-off valve. The valve can have a nominal diameter of (at least) 3 inches, preferably (at least) 4 inches.

[0028] The soot blower has a lance tube with at least one nozzle for delivering the cleaning gas. The lance tube extends, in particular, along its longitudinal axis, which is preferably straight. The lance tube can have a length of up to 15,000 mm, particularly parallel to its longitudinal axis. The lance tube can have at least one outer tube and at least one inner tube. The inner tube can be located at least partially within the outer tube. The outer tube and the inner tube can extend along the longitudinal axis of the lance tube. The outer tube and the inner tube can be telescopically extendable relative to each other. The nozzle can be located in the circumferential wall of the outer tube. The lance tube or the outer tube can have a plurality or multiple nozzles for the cleaning gas.The nozzle has a diameter of at least 8 mm, preferably at least 11 mm, particularly preferably 11 mm to 30 mm, and most preferably 11.5 mm to 16 mm. The large diameter of the nozzle, compared to conventional soot blowers, allows for a sufficiently deep cleaning of the cleaning gas even at a low gas outlet pressure.

[0029] The lance tube (or at least one outer tube) can have a first inner diameter of at least 100 mm, at least partially (especially perpendicular to the longitudinal axis of the lance tube). This first inner diameter is larger than that of conventional soot blowers for air preheaters and reduces pressure loss of the cleaning gas, allowing the use of a low-pressure cleaning gas source while still achieving effective cleaning results. The lance tube has an inner tube with a second inner diameter of at least 75 mm. This second inner diameter is measured perpendicular to the longitudinal axis of the lance tube. The inner tube can, in particular, extend coaxially with the outer tube.

[0030] The outer pipe and / or the inner pipe are in particular metal pipes.

[0031] The lance tube may be insulated. This insulation is primarily thermal insulation, designed to at least reduce the temperature drop of the cleaning gas within the soot blower. The insulation may be applied to at least one outer tube and / or at least one inner tube. For example, the insulation may be a coating.

[0032] The lance tube can be rotatable about a longitudinal axis. In particular, the outer tube can be rotatable about the longitudinal axis of the lance tube. This allows at least one nozzle to be pivoted about the longitudinal axis of the lance tube, for example by 30° to 150°, preferably by 80° to 100°, and most preferably by (essentially) 90°.

[0033] For further details on the use, please refer in full to the description of the procedure.

[0034] Following a further aspect, a soot blower for cleaning an air preheater of a combustion boiler is proposed, which has at least the following features:

[0035] - a valve for a cleaning gas; and

[0036] - A lance tube with at least one nozzle for dispensing the cleaning gas, the nozzle having a diameter of at least 11 mm. The soot blower is specifically designed and configured for carrying out the procedure described herein.

[0037] The nozzle preferably has a diameter of 11 mm to 30 mm, particularly preferably 11.5 mm to 16 mm. The large diameter of the nozzle, compared to conventional soot blowers, allows for a sufficiently deep cleaning of the cleaning gas even at a low gas outlet pressure.

[0038] For further details on the soot blower, please refer to the description of the process and its use.

[0039] The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the figures show a particularly preferred embodiment of the invention, but that the invention is not limited to this embodiment. Identical components in the figures are designated with the same reference numerals. The figures show, by way of example and schematically:

[0040] Fig. 1 : a power plant with a combustion boiler and an air preheater in a side view;

[0041] Fig. 2: a rotor of the air preheater with soot blowers in a perspective view;

[0042] Fig. 3: a soot blower in a side view; and

[0043] Fig. 4: an enthalpy-entropy vapor diagram.

[0044] Fig. 1 shows a side view of a power plant 13. The power plant 13 comprises a combustion boiler 2, to which combustion air can be supplied via an air supply duct 14. Hot flue gases are produced during the combustion of fuel in the combustion boiler 2. The combustion boiler 2 has heat exchanger tubes (not shown in Fig. 1) with which thermal energy from the flue gases can be transferred to water or a steam system. The generated steam can be used to drive a turbine for electricity generation. The flue gases flow via a primary flue 15 and secondary flue 16 of the combustion boiler 2 to an electrostatic precipitator 17 and then via a flue gas desulfurization unit 20 to a chimney 18, through which the cleaned flue gases can be released into the surroundings 19 of the power plant 13.

[0045] The hot flue gases flow through an air preheater 1, which is arranged downstream of the flue gas flow towards the combustion chamber 2. The air preheater 1 serves to preheat the combustion air. For this purpose, the air preheater 1 extracts thermal energy from the flue gases and transfers it to the combustion air. The air preheater 1 is a rotary heat exchanger whose rotor 22 (see Fig. 2) rotates about an axis of rotation 21.

[0046] Fig. 2 shows a perspective view of a rotor 22 of the air preheater 1 shown in Fig. 1. The rotor 22 is housed in a casing shown in Fig. 1.

[0047] The rotor 22 of the air preheater 1 is rotatable about the axis of rotation 21. The axis of rotation 21 can be vertical. The rotor 22 is permeable to flue gas in a first sector 24 of the air preheater 1 and to combustion air in a second sector 25 of the air preheater 1. For this purpose, the rotor 22 can have a plurality of flow channels for the flue gas and the combustion air. The flow channels can extend parallel to the axis of rotation 21 through the rotor 22. The flow channels can be formed by a plurality of, in particular thin and / or corrugated, metal plates or sheets of the rotor 22. The rotor 22 rotates continuously about the axis of rotation 21 through the first sector.

[0048] The flue gases heat the section of the rotor 22 located in the first sector 24 of the air preheater 1. The heated section of the rotor 22 then rotates into the second sector 25 of the air preheater 1 and heats the combustion air there. A first soot blower 3 is arranged on a combustion air inlet side 26 or on a flue gas outlet side 29 of the rotor 22, and a second soot blower 3 is arranged on a combustion air outlet side 27 or on a flue gas inlet side 28 of the rotor 22. Each soot blower 3 has a lance tube 7 with a nozzle 4. A cleaning gas can be blown through the nozzles 4 into the flow channels of the rotor 22 to clean these channels.

[0049] Fig. 3 shows a side view of one of the soot blowers 3 shown in Fig. 2. The soot blower 3 is arranged outside the air preheater 1 shown in Fig. 1, or rather outside the housing 23 of the air preheater 1. The soot blower 3 has a frame 30 to which the lance tube 7 is attached. The lance tube 7 comprises an inner tube 10 and an outer tube 11, which extend along a (straight) longitudinal axis 12. The inner tube 10 has a first inner diameter 8 and the outer tube 11 has a second inner diameter 9. The lance tube 7 is telescopic. The outer tube 11 is movable relative to the inner tube 10 by means of a slide 38 parallel to the longitudinal axis 12. In Fig. 3, the soot blower 3 is in a rest position in which the outer tube 11 has been extended out of the air preheater 1 shown in Fig. 1. To clean the air preheater 1, the outer tube 11 is removed through an opening in the part shown in Fig.The housing 23 of the air preheater 1 shown in the illustration can be moved into the air preheater 1.

[0050] The cleaning gas can be supplied to the lance tube 7 or the inner tube 10 via a cleaning gas inlet 31. The cleaning gas can flow from the cleaning gas inlet 31 through the inner tube 10 into the outer tube 11 and can be discharged via the nozzle 4 of the outer tube 11 (essentially orthogonal to the longitudinal axis 12 of the lance tube). The nozzle 4 is arranged in a circumferential wall 32 of the outer tube 11 and has a diameter 5. The discharge of the cleaning gas can be controlled via a valve 6 of the soot blower 3.

[0051] Figure 4 shows an enthalpy-entropy vapor diagram, also called a Mollier diagram. The enthalpy-entropy vapor diagram is used in thermodynamics to represent changes of state of water and vapor, as they occur in many technical applications. Enthalpy is plotted on the vertical y-axis and entropy on the horizontal x-axis. Pressure is represented by isobaric lines (lines of equal pressure), temperature by isothermal lines (lines of equal temperature), and vapor content by lines of equal vapor content (also known as degree of dryness or vapor fraction).

[0052] To clean the air preheater 1 shown in Fig. 1, cleaning gas with a gas inlet temperature of, for example, 500 °C and a gas inlet pressure of, for example, 3 MPa can be supplied to the soot blower 3 shown in Fig. 3 at the cleaning gas inlet 31. This is represented by a first point 33 in the enthalpy-entropy vapor diagram in Fig. 4. The pressure of the cleaning gas in the soot blower 3 can be throttled to, for example, 1.4 MPa by a throttle 36 (see Fig. 3) located inside the valve 6, which is represented by a second point 34 in the enthalpy-entropy vapor diagram in Fig. 4. The first inner diameter 8 of the inner tube 10 is at least 100 mm in order to reduce the pressure loss of the cleaning gas within the lance tube 7. The pressure of the cleaning gas drops to ambient pressure of (essentially) 0.1 MPa after being discharged through nozzle 4, resulting in a decrease in the temperature of the cleaning gas. This is shown in the enthalpy-entropy vapor diagram in Fig.Figure 4 shows a third point 35. The cleaning gas is supplied to the soot blower 3 at such a high gas inlet temperature that the gas outlet temperature, at which the cleaning gas flows into the rotor 22 of the air preheater 1, is at least 180 °C. The gas outlet temperature is therefore significantly higher than the saturated steam temperature that would be required to achieve saturated steam. This is illustrated by an arrow 37 in the enthalpy-entropy steam diagram in Figure 4.

[0053] Due to the high gas outlet temperature of the cleaning gas, impurities in the rotor 22 are first decomposed or vaporized / melted and then removed by the cleaning gas, the flue gas and / or the combustion air.

[0054] The invention allows the air preheater 1 to be reliably cleaned and prevents damage to the air preheater 1. Reference numeral list

[0055] 1 air preheater

[0056] 2 combustion boilers

[0057] 3 soot blowers

[0058] 4 nozzles

[0059] 5 diameters

[0060] 6 valve

[0061] 7 lance tubes

[0062] 8 first inner diameter

[0063] 9 second inner diameter

[0064] 10 inner tube

[0065] 11 Outer pipe

[0066] 12 Longitudinal axis of the lance tube

[0067] 13 Power plant

[0068] 14 Air supply duct

[0069] 15 Primary train

[0070] 16 Secondary train

[0071] 17 Electrostatic precipitators

[0072] 18 Chimney

[0073] 19 surroundings

[0074] 20 Flue gas desulfurization unit

[0075] 21 axis of rotation

[0076] 22 Rotor

[0077] 23 cases

[0078] 24 first sector

[0079] 25 second sector

[0080] 26 Combustion air supply side

[0081] 27 Combustion air outlet side

[0082] 28 Flue gas inlet side

[0083] 29 Flue gas exhaust side

[0084] 30 frames

[0085] 31 Cleaning gas inlet 32 ​​Perimeter wall

[0086] 33 first point

[0087] 34 second point

[0088] 35 third point 36 throttle

[0089] 37 Arrow

[0090] 38 sleds

Claims

Patent claims 1. Method for cleaning an air preheater (1) of a combustion boiler (2), comprising at least the following steps: a) providing a soot blower (3); and b) cleaning the air preheater (1) using the soot blower (3), wherein the soot blower (3) discharges a cleaning gas with a gas outlet temperature of at least 180 °C.

2. Method according to claim 1, wherein in step b) contaminants of the air preheater (1) are evaporated, melted or decomposed and the contaminants are subsequently at least partially removed by the cleaning gas, flue gas or combustion air.

3. Method according to one of the preceding claims, wherein in step b) the gas outlet temperature is 180 °C to 320 °C.

4. Method according to one of the preceding claims, wherein the cleaning gas is supplied to the soot blower (3) with a gas inlet temperature of at least 400 °C.

5. Method according to claim 4, wherein the gas inlet temperature is 400 °C to 650 °C.

6. Method according to one of the preceding claims, wherein the cleaning gas is supplied to the soot blower (3) with a gas inlet pressure of at least 1.2 MPa.

7. Method according to claim 6, wherein the gas inlet pressure is 2.5 MPa to 7 MPa.

8. Method according to one of the preceding claims, wherein the cleaning gas is discharged via at least one nozzle (4) having a diameter (5) of at least 8 mm.

9. Method according to claim 8, wherein the diameter (5) of the at least one nozzle (4) is 8 mm to 30 mm.

10. Method according to one of the preceding claims, wherein the cleaning gas is discharged via at least one nozzle (4) which is pivoted by 30° to 150° according to step b).

11. Method according to one of the preceding claims, wherein the cleaning gas is discharged at a gas outlet pressure of 0.2 MPa to 0.8 MPa.

12. Use of a soot blower (3) for cleaning an air preheater (1) of a combustion boiler (2), wherein the soot blower (3) discharges a cleaning gas with a gas outlet temperature of at least 180 °C and wherein the soot blower (3) has at least the following features: - a valve (6) for a cleaning gas; and - a lance tube (7) with at least one nozzle (4) for the discharge of the cleaning gas, wherein the nozzle has a diameter (5) of at least 8 mm.

13. Use according to claim 12, wherein the lance tube (7) has at least partially a first inner diameter (8) of at least 100 mm.

14. Use (3) according to claim 12 or 13, wherein the lance tube (7) has an inner tube (10) with a second inner diameter (9) of at least 75 mm.

15. Use (3) according to any one of claims 12 to 14, wherein the lance tube (7) has insulation.

16. Use (3) according to one of claims 12 to 15, wherein the lance tube (7) is rotatable about a longitudinal axis (12) of the lance tube.

17. Soot blower (3) for cleaning an air preheater (1) of a combustion boiler (2), comprising at least the following: - a valve (6) for a cleaning gas; and - a lance tube (7) with at least one nozzle (4) for dispensing the cleaning gas, wherein the nozzle has a diameter (5) of at least 11 mm.

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