Pressure Wave Generator

Abstract

The present invention relates to a pressure wave generator (DWG) and a system and method for generating pressure waves, in particular for cleaning a vessel, for example a steam boiler or a pipe. The DWG comprises a pressure chamber (11, 12) which can be filled with a working medium via a pressure chamber inlet, at least two opposing pressure outlets (15), an actuator chamber (18) which can be filled with an actuator medium via an actuator chamber inlet (5), and at least two opposing actuator outlets (8) connected to the pressure chamber (11, 12) by a passage. The DWG further comprises a closure element (13) in the pressure chamber (11, 12), which in a closed position closes the pressure chamber (11, 12) against the pressure outlets (15) and in an open position allows the working medium to flow out of the pressure outlets (15). The DWG also includes an actuator element (6) in the actuator chamber (18) which in a closed position closes the pressure chambers (11, 12) to the actuator outlet (8) and in an open position allows the working medium to flow through the passage (7) and the actuator outlet (8).

Description

[Technical field]

[0001] The present invention relates to a pressure wave generator (DWG) and a system for generating pressure waves, as well as a method for generating pressure waves and the use of the DWG, the system or the method.

[0002] background

[0003] DWGs can be used, for example, in power plants to clean dirty tanks, pipes or steam boilers. Such DWGs are described, for example, in WO 2021 / 078754 A1. Compressed air is forced into a pressure chamber, for example at 100 bar. When the air suddenly escapes from the pressure chamber, a very fast air flow occurs, which generates a strong pressure wave with high total pressure in the vicinity of the DWG. When this pressure wave hits the contaminated surfaces of the tank, pipe or steam boiler, it exerts a strong force on the contaminants present, for example deposits and solidified material, blowing them away.

[0004] Known DWGs have various drawbacks. On the one hand, they have a large form factor due to the volume of compressed air required and have a high weight, especially in the range of several hundred kilograms. As a result, such DWGs are hardly usable for mobile applications, in particular because they cannot be handled by hand and brought into the room to be cleaned. On the other hand, part of the potential energy stored with the compressed air in the DWG is dissipated inside the DWG, for example by impact on the walls of the pressure chamber, or outside, for example by omnidirectional propagation of pressure waves in directions free of contamination.

[0005] DISCLOSURE OF THEINVENTION

[0006] Therefore, there is a need for an improved pressure wave generator (DWG). One possible object of the present invention is to provide a DWG that can be operated by hand, in particular in places where access is difficult. Another object of the present invention is to provide a DWG with improved cleaning effect. Furthermore, an object of the present invention is to provide a correspondingly improved method for generating pressure waves. [Pressure wave generator]

[0007] One or more of the above problems are solved by the DWG according to the present invention, which is designed to generate pressure waves in the environment of the DWG and in particular to produce a cleaning effect via pressure waves, for example on contaminated containers, contaminated pipes or steam boilers.

[0008] Such a DWG is a pressure chamber which can be filled with a working medium, in particular compressed air, via a pressure chamber inlet, and which has at least two pressure outlets located opposite each other; an actuator chamber which can be filled with an actuator medium, in particular compressed air, via an inlet in the actuator chamber; at least two opposed actuator outlets connected to the pressure chamber by passageways; a closure element in the pressure chamber, which in a closed position closes the pressure chamber against the pressure outlet and in an open position allows the working medium to flow through the pressure outlet; An actuator element; The pressure chamber includes a closure element at least partially disposed between the passage and the pressure outlet. Advantageously, the closure element can be moved from the closed position to the open position by sliding it axially. The pressure outlet is advantageously disposed substantially radially outward. In this context, "radial" should be understood as any direction perpendicular to the "axial" direction. "Essentially radial" is intended to include in particular a deviation from the radial direction of up to 45°, in particular up to 30°.

[0009] The actuator element in the actuator chamber, in the closed position, closes the pressure chamber against the actuator outlet and, in the open position, allows the working medium to flow out, in particular from the pressure chamber, through the passage and the actuator outlet. The actuator element is arranged in the actuator chamber between the actuator chamber inlet and the passage. Advantageously, the actuator chamber inlet is sealed against the passage by the actuator element, in particular without a passage opening. Advantageously, the actuator element can also be moved from the closed position to the open position by sliding it axially. The actuator outlet is advantageously arranged essentially radially outward.

[0010] In operation with a working medium, the closure element can be moved from the closed position to the open position by moving the actuator element from the closed position to the open position. This can be achieved in particular by a "pneumatic actuator" comprising an actuator element and advantageously a second actuator element, as shown below. [Pressure chamber and actuator chamber]

[0011] According to one embodiment, the pressure chamber is essentially cylindrical and the closure element comprises a hollow cylinder with one open end. The opposite end of the hollow cylinder is substantially closed. However, the opposite end can have a passage opening, particularly located in the center, through which the interior of the hollow cylinder can be filled with the working medium. In this case, the outer surface of the closure element must be in tight, particularly gas-tight, contact with the inner surface of the pressure chamber. In particular, a seal is fitted between the outer surface of the closure element and the inner surface of the pressure chamber.

[0012] Advantageously, the closed end face of the closure element has an inner surface facing inwards, in particular at least 5% smaller than the opposite outer surface. This has the effect that when the pressure chamber is closed, in particular when the actuator element is in the closed position, the closure element also remains in the closed position. According to the general formula F=p·A, the difference in area A between the outer and inner surfaces of the closure element results in an effective force F on the closure element in the direction of the closed position, since the pressure p is the same on both sides in the steady state.

[0013] When the passage is opened, in particular by moving the actuator element into the open position, the working medium flows out through the passage and the actuator outlet. This causes a rapid drop in pressure on the outer surface of the closing element. On the other hand, on the inner surface of the closing element, the pressure is only slowly reduced, i.e. only through the passage opening, as long as the closing element is in the closed position. As a result, an effective force acts on the closing element in the direction of the open position, which moves the closing element into the open position, thereby opening the pressure outlet of the pressure chamber, and the working medium, in particular the working medium from the inside of the closing element, quickly escapes. By "rapidly" it is understood in particular that the half-value time of the pressure of the working medium in the pressure chamber after moving the actuator element into the open position is at most 10 ms, in particular at most 6 ms.

[0014] In general, the DWG generates pressure waves at both the pressure outlet and the actuator outlet. Thus, the described configuration effectively uses both the total volume of the pressurized working medium in the pressure chamber, in particular the partial volume on the outer surface of the closure element and the partial volume on the inner surface of the closure element, to generate pressure waves with a cleaning effect. This can enhance the cleaning effect.

[0015] In one embodiment, the pressure chamber is between 1.2 and 2 times, in particular between 1.4 and 1.7 times, larger than the interior of the closure element. This allows the closure element to be easily moved between the closed and open positions. In particular, the interior of the closure element can have a volume of 1-2 liters and the pressure chamber can have a volume of 1.5-3 liters. Furthermore, the closure element can have an outer diameter of 100-150 mm.

[0016] The passage opening in the closure element advantageously has a diameter of 1 to 10 mm, in particular 3 to 5 mm, such dimensions allowing the closure element to be easily moved between the closed and open positions and at the same time allowing rapid filling of the pressure chamber with the working medium, for example within a maximum of 5 seconds, in particular within a maximum of 3 seconds.

[0017] In one embodiment, the pressure chamber can be filled with an actuating medium, in particular air, at a pressure of at least 100 bar, in particular at least 200 bar. In addition, the actuator chamber can be advantageously filled with an actuator medium, which is the same as the actuating medium, at a pressure of at least 10 bar. With such dimensions, the pressure chamber can be filled with a volume of air, for example, having a volume of at least 150 liters at 1 bar, in particular at least 300 liters. In particular, when moving the closing element from the closed position to the open position, a speed of at least 15 m / s, in particular at least 30 m / s, can be achieved. This generates a sufficiently strong pressure wave, which can remove even persistent dirt, for example, hardened soot and corrosion products such as rust.

[0018] Furthermore, the actuator element closing the passage from the pressure chamber in the closed position must be dimensioned such that it remains in the closed position when the pressure chamber and the actuator chamber are full, depending on the pressure of the actuating medium and the pressure of the actuator medium. The actuator element should only be moved to the open position when the pressure of the actuator medium is reduced. This is achieved in that one end face of the actuator element directed towards the passage is smaller than the opposite end face directed towards the actuator chamber inlet. The required ratio of the end faces can be calculated using the general formula F=p·A, depending on the pressure of the actuator medium and the actuating medium. [Pressure outlet and actuator outlet]

[0019] The fact that at least two pressure outlets are arranged opposite each other, in other words symmetrically, in particular axially symmetrically on the DWG, has the effect that at least the radial components of the recoil forces on the DWG caused by the outflowing working medium cancel each other out. The same applies to at least two actuator outlets arranged opposite each other on the DWG. In this way, the DWG can be operated hand-held. The DWG can thus be designed as a mobile device that can be held manually, for example, in a dirty boiler. Without a special arrangement of the outlets, the recoil forces of the outflowing working medium would make the DWG too large and mobile handling would be impossible.

[0020] In one embodiment, the total open area of ​​the pressure outlet is at least as large as the open end surface of the hollow cylinder, in particular at least 20% larger. This allows the working medium to be quickly discharged from the pressure chamber as soon as the closing element is in the open position, thus obtaining a high discharge velocity and a strong pressure wave. Advantageously, the discharge velocity at the narrowest point, e.g. the pressure outlet, is approximately Mach 1, so that the strongest possible pressure wave is achieved. Furthermore, the described dimensions of the pressure outlet prevent the working medium from exerting excessive forces on the components of the DWG during discharge, in particular on the components adjacent to the pressure outlet, which may cause damage to the DWG, at least over a long period of time.

[0021] In one embodiment, at least two pressure outlets on at least two sides of the pressure wave generator each include at least three outlet openings. The outlet openings can be designed with a substantially square cross section. Such a design of the pressure outlets produces strong pressure waves that are directed in an angular range of, for example, 90 degrees, thus achieving a good cleaning effect in this angular range.

[0022] The actuator outlet may also comprise one or more outlet openings, for example in the form of an elongated outlet slot, or in particular having a square cross section. Again, the shape of the outlet may be used to affect the intensity and directional characteristics of the generated pressure wave.

[0023] Furthermore, it is advantageous for the at least two actuator outlets to be oriented essentially the same as the at least two pressure outlets, in particular with a deviation of no more than 30 degrees.

[0024] In particular, the actuator outlet can be located at essentially the same angular position on the DWG as the pressure outlet. Such an arrangement has the effect that the pressure waves generated at the actuator outlet and the pressure outlet are directed to the same angular range, reinforcing their cleaning effects on each other.

[0025] In one embodiment, the total open area of ​​the actuator outlet or the passage to the actuator outlet is smaller than the total open area of ​​the pressure outlet. In particular, the total open area of ​​the actuator outlet or the passage can be smaller than half of the total open area of ​​the pressure outlet. This has the advantage that when the closure element is moved to the open position, the pressure of the working medium decreases more slowly through the actuator outlet than through the pressure outlet, so that the working medium remaining in the pressure chamber outside the closure element acts as a gas spring and damps the movement of the closure element. This in turn avoids a strong impact of the closure element inside the pressure chamber, thus improving both the manageability and the service life of the DWG. [Second Actuator Chamber]

[0026] In an advantageous embodiment, the DWG further comprises a second actuator chamber, which can be filled with an actuator medium via a second actuator chamber inlet and at least two second actuator outlets are placed opposite each other. The second actuator chamber and the actuator chamber are connected by a second passage, which advantageously corresponds to the actuator chamber inlet and - a second actuator element in the second actuator chamber, which in a closed position closes the actuator chamber and the second actuator chamber to the second actuator outlet and in an open position allows actuator medium to flow through the second passageway and the second actuator outlet, the second actuator element being disposed in the second actuator chamber between the second actuator chamber inlet and the second passageway.

[0027] For a simple and compact design, the actuator chamber may be filled with actuator medium via the second actuator chamber and the second actuator chamber inlet.

[0028] Advantageously, the second actuator chamber and the second actuator element are cylindrical. A cylindrical shape generally has the advantage that the pressurizing force is distributed without excessively acting on individual components or wall parts, while at the same time allowing a piston-like displacement of the (second) actuator element in the (second) actuator chamber or the closure element in the pressure chamber.

[0029] Furthermore, the second actuator element can have a passage opening, in particular a central passage opening. The actuator chamber can also be filled with actuator medium from the second actuator chamber inlet via this passage opening. Advantageously, the second actuator element is in principle similar to the closing element, but is formed such that the end face aligned with the actuator chamber is smaller, in particular at least 5% smaller, than the end face aligned with the second actuator chamber inlet. This then has the effect that, as described above in connection with the closing element, when the actuator chamber and the second actuator chamber are filled, the second actuator element remains in the closed position, thus closing the second actuator outlet. As a result, the actuator element and the closing element also remain in the closed position, allowing the pressure chamber to be filled with actuating medium.

[0030] In an advantageous embodiment, the DWG further comprises a controllable drain valve, in particular for the second actuator chamber inlet, for triggering the drain of the actuator medium from the actuator chamber. Advantageously, the drain valve comprises a solenoid valve. By opening the drain valve, the above-mentioned "pneumatic actuator" is operated as follows: the pressure in the second actuator chamber decreases as the actuator medium flows out through the drain valve. As a result, the second actuator element is moved to the open position with an effective force in the direction of the open position and the second actuator outlet is released. Now the actuator medium also flows out of the actuator chamber quickly, in particular via the second actuator outlet. As a result, the pressurized actuating medium exerts an effective force on the actuator element in the direction of the open position. The actuator element moves to the open position and releases the actuator outlet so that the actuating medium flows out from it, and the closing element moves to the open position as described above and a pressure wave is generated. [Further aspects of DWG]

[0031] It is inevitable that the flow of the working medium when exiting the pressure outlet has an axial component of flow velocity in addition to the radial component, especially while the closing element is moving to the open position. As a result, the recoil force on the DWG also includes an axial component that is not compensated for by the above-mentioned clever arrangement of the pressure outlet, which has undesirable effects on the operator, especially under manual operation.

[0032] In order to minimize this recoil, in an advantageous embodiment, at least one protrusion is provided on the outside of the drawing board, adjacent to at least two pressure outlets in the direction of the end face of the drawing board. At the same time, the pressure outlet should also be arranged in the part of the pressure chamber facing the end face of the drawing board, in particular the closing element should be located close to the end face in the closed position and away from the end face in the open position. Such an arrangement of the pressure outlets results in an axial component of the flow velocity of the outflowing working medium in the direction of the end face. The protrusion is advantageously arranged to influence, in particular to deflect, the flow of the working medium exiting through the pressure outlet. When the flow hits the protrusion, a force acts on the drawing board that at least partially compensates for the axial component of the recoil force, in particular at least 50%. A suitable protrusion is, for example, a rib that protrudes at least 1 cm and advantageously runs parallel to the end face. In an advantageous embodiment, the at least one protrusion is designed as a ring that continues adjacent to and around the at least two pressure outlets.

[0033] In this way, a DWG can be provided that can be held by hand during operation, i.e. hand-held and operable. Such manual maneuverability facilitates, accelerates and improves the cleaning of soiled vessels, since the DWG can be held at the point to be cleaned without great effort, for example by repeated assembly.

[0034] Here, the weight of the DWG naturally also plays an important role. Advantageously, the DWG has a weight of 12 kg or less, in particular 7 kg or less. This can be achieved by manufacturing the main components of the DWG, in particular the pressure chamber, the actuator chamber, the second actuator chamber, the closure element, the actuator element and / or the second actuator element, from aluminum. The reduced weight also improves handling. [System that generates pressure waves]

[0035] Another aspect of the invention relates to a system for generating pressure waves. The system comprises a DWG as described above and a lance to whose distal end the DWG is attached. At the proximal end of the lance the system can be held by a user and controlled from there. The lance comprises a first supply line for the actuation medium and a second supply line for the actuator medium. Furthermore, the lance advantageously includes a control line for controlling the discharge valve, for example an electrical line in case of a solenoid valve.

[0036] Such a system makes it possible to clean contaminated vessels, in particular pipes or boilers, even in remote locations, without the user having to enter the vessel himself. For this purpose, the lance may be at least 3 m long, in particular at least 5 m long. In particular, such a system makes it possible to clean contaminated vessels during operation, without stopping their operation, for example in the case of power plants or generators.

[0037] Especially in the latter application, the DWG or the system must be designed to withstand temperatures of several hundred °C, in particular at least 900 °C. The following embodiment is advantageous for this purpose: The lance comprises a multi-chambered hollow profile. The outer chamber of the hollow profile is designed to supply cooling water and / or cooling air for the DWG to the distal end of the lance. At the distal end, the lance may in particular have an outlet opening arranged so that during operation the cooling water drips or flows over the DWG to cool it. Furthermore, the first and second supply lines, in particular the control lines, run inside the inner chamber of the hollow profile. In this way, the supply lines and the control lines are also protected from high temperatures during operation, which allows cleaning at high temperatures, in particular during operation of the power plant.

[0038] In a further embodiment, the system comprises a camera attached to the pressure wave generator, in particular to the end face of the pressure wave generator, and set to inspect the area surrounding the pressure wave generator. Infrared cameras (IR cameras) have proven to be particularly suitable for inspecting contaminated areas. The camera can better recognize the dirty areas and can better align the DWG to these areas, thus accelerating and / or improving the cleaning of the dirty containers.

[0039] Advantageously, the system also comprises at least one storage bottle to which the first and second supply lines are connected. The at least one storage bottle can contain a total volume of working medium or actuator medium of, for example, 200-300 liters. In practice, the at least one storage bottle can be filled with working medium or actuator medium using a compressor up to a pressure of more than 300 bar, for example 330 bar. Compressors with a capacity of at least 500 to 800 liters / min at 330 bar have proven to be particularly practical for this purpose. [How to generate pressure waves]

[0040] A further aspect of the invention relates to a method of generating pressure waves, in particular for cleaning contaminated containers, which method is carried out using the above mentioned DWG and comprises the following steps: (a) filling an actuator chamber with a gaseous actuator medium at a pressure above 10 bar, in particular below 50 bar; (b) filling the pressure chamber with a gaseous working medium at a pressure of more than 100 bar, in particular more than 200 bar; (c) moving the actuator element from the closed position to the open position, thereby discharging the pressurized working medium from the pressure chamber through the pressure outlet and the actuator outlet. As described above, the rapid discharge of the working medium in the pressure chamber due to the high pressure generates a pressure wave at the pressure outlet and the actuator outlet, which provides a good cleaning effect.

[0041] To obtain a good cleaning effect, it is advantageous for the pressurized working medium to be discharged from the pressure chamber in step (c) with a half-time of less than 10 ms, in particular less than 6 ms. Such a half-time can be achieved using a drawing having the above-mentioned dimensions.

[0042] According to one embodiment, the working medium, in particular the actuator medium, is air. In particular, the pressure chamber can be filled with air at 1 bar, in a volume having a pressure of at least 150 bar, in particular a volume of at least 300 liters.

[0043] Furthermore, in embodiments having a second actuator chamber, it is advantageous that in step (a) the actuator chamber is filled via a passage opening in the second actuator chamber and the second actuator element. This avoids a separate inlet for the actuator chamber and allows for a compact design. On the other hand, the pressure chamber advantageously has its own pressure chamber inlet.

[0044] Furthermore, the movement of the actuator element in step (c) is in one embodiment effected by exhausting actuator medium from the actuator chamber via the actuator chamber inlet, in particular by exhausting actuator medium from the second actuator chamber via the second actuator chamber inlet, in particular by opening an exhaust valve - see description of "Pneumatic actuator" above.

[0045] In continuous operation when cleaning contaminated containers, the DWG is usually not only actuated once, i.e. not only generates a single pressure wave, but also "shoots" at regular intervals. The method therefore advantageously comprises repeating steps (a), (b) and (c) with a pressure wave interval of at most 10 seconds, in particular at most 5 seconds. Thus, theoretically, at least 6, in particular at least 12 "shots", i.e. pressure waves, are generated per minute. In particular, the method for cleaning containers further comprises the step of moving the DWG, in particular by hand, to the next position to be cleaned. [Use DWG]

[0046] The features of the DWG or system for generating pressure waves described above are intended to be disclosed in relation to said method and vice versa.Furthermore, the present invention relates to the use of the DWG, the system or the method for cleaning contaminated vessels, pipes or steam boilers.Such vessels, pipes and steam boilers are typically part of power plants, for example coal-fired, waste-fired, biomass-fired or gas turbine power plants.

[0047] Thus, when used in coal-fired power plants, the DWG primarily cleans the vessel's surfaces from dirt caused by combustion products, e.g. soot. As explained, this can be done even while the power plant is operated, i.e. while hot flue gases circulate inside the vessel.

[0048] When used in gas turbine combined cycle power plants, DWG mainly removes rust from the finned tube surfaces of downstream steam boilers, which is formed as a corrosion product during further utilization of the residual heat contained in the exhaust gas.

[0049] If the surroundings of the DWG are rather cold, especially below 100 °C, for example in the downstream boiler of a gas turbine power plant, a configuration with a wire rope hoist instead of the lanced system described above is also conceivable. In this case, the DWG is attached to a rope hoist that is configured so that the DWG can reach and clean the entire surface of the tube bundle in the tank. In particular, the position of the DWG can be automatically controlled via the rope hoist and a computer implemented control system and adapted to the respective vessel. [Brief description of the drawings]

[0050] Further embodiments, advantages and applications of the invention are evident from the dependent claims and the following description of the drawings. [Figure 1] FIG. 1 is a schematic diagram of a pressure wave generator (DWG) according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a system for generating pressure waves according to an embodiment of the invention in use. [Diagram 3] FIG. 3 is a schematic diagram of a system for generating pressure waves according to an embodiment of the invention in use.

[0051] Methods of carrying out the invention

[0052] The structure of the DWG is shown diagrammatically in Figure 1. The housing 16, advantageously made of aluminium for weight reasons, encloses the pressure chamber consisting of the interior 12 and the gas spring chamber 11, the actuator chamber 18 and the second actuator chamber 19.

[0053] Within the cylindrical pressure chambers 11, 12 there is a hollow cylinder 13 which acts as a closure member as described above. The hollow cylinder 13 encloses the interior 12 and in its closed position (shown in FIG. 1) closes the pressure outlet 15 from the pressure chambers 11, 12 to the surroundings of the DWG. The outer diameter of the hollow cylinder is, for example, of the order of 0.1 m. The volume of the interior chamber 12 may be, for example, of about 1 liter and the volume of the gas spring chamber 11 may be, for example, of about 0.6 liter. To prevent the working medium from escaping from the gas spring chamber 11 through the pressure outlet 15, a seal 13a, for example a Teflon O-ring, is fitted between the hollow cylinder 13 and the inner wall of the housing 16.

[0054] For optimal sealing, the housing 16 can generally have a sealing layer 14, especially made of Teflon, at the end face of the DWG, against which the hollow cylinder 13 is pressed in the closed position. The pressure chamber can be filled with a pressurized working medium, for example air, via a valve-controlled supply line 10. The pressure of the working medium in the pressure chamber can be more than 200 bar in order to generate powerful pressure waves with a high cleaning effect. When the pressure chamber is closed, this pressure is equalized via the passage opening 17 in the hollow cylinder 13, resulting in a state of equilibrium, so that it acts both on the gas spring chamber 11 and on the interior 12.

[0055] Located in the actuator chamber 18 is the actuator element 6, which also has a cylindrical shape. In the closed position (shown in FIG. 1 ), the actuator element 6 closes the flow passage 7 between the pressure chamber, in particular the gas spring chamber 11, and the actuator outlet 8. The actuator element 6 seals against the inner wall of the actuator chamber 18. For this purpose, a sealing ring 6a, for example comprising Teflon, can for example be inserted into the inner wall of the actuator chamber.

[0056] Within the second actuator chamber 19 is a second actuator element 2 having a through hole 5 (similar to the hollow cylinder 13). In its closed position (shown in FIG. 1 ), the second actuator element 2 closes the flow path 3 between the actuator chamber 18 and the second actuator outlet 4. The second actuator element 2 is also sealed against the inner wall of the housing by a seal 2a, e.g. an O-ring with Teflon.

[0057] The second actuator chamber 19 and the actuator chamber 18 are filled with an actuator medium, for example air, under pressure from a valve-controlled supply line 1 via a through hole 5. A release valve 9, also fitted at the inlet of the second actuator chamber 19, is closed. The pressure in the actuator chamber 18 is typically significantly lower than the pressure in the pressure chamber, in particular about an order of magnitude lower. In particular, the actuator chamber 18 is filled with air at a pressure of 8 to 25 bar, for example about 20 bar.

[0058] The supply valves 1, 10 and the discharge valve 9 are preferably solenoid valves which can be controlled via electrical pulses. The control system is advantageously designed as a computer or hardware implemented control system such that the valves open and close automatically during operation.

[0059] Placing the discharge valve 9 in the vicinity of the second actuator chamber 19 is advantageous in that the actuator medium can be quickly discharged. In particular, the discharge valve should be located within 1 m of the second actuator chamber 19. For reasons of robustness and compact design, the discharge valve 9 is preferably integrated in the housing 16. On the other hand, the supply valves 1, 10 can be located further away from the housing 16, for example at the end of the lance or even more than 1 m or even more than 3 m away from the housing 16. In particular, as mentioned above, if the DWG is attached to the lance, the supply valves 1, 10 can be located in a supply and control unit, for example, which also houses the pressurized gas cylinder and is connected upstream of the lance. This is an advantage, as the system made up of the lance and the DWG is intended to be mobile and is light, so that it can be held by hand.

[0060] The "fire cycle" in which a pressure wave is generated during the operation of the DWG proceeds as follows: 1. The actuator medium supply valve 1 is opened. The actuator pressure rises in front of the second actuator element 2, forcing it onto its seat in the flow passage 3 and closing the second actuator outlet 4. Valves 9 and 10 remain closed during this phase. 2. Now the actuator medium flows through the small through hole 5 into the actuator element 6 and forces it into the seat of the passage 7, i.e. in the closed position, whereby the actuator outlet 8 is closed. 3. The power supply valve 10 is opened and the gas spring chamber 11 and interior 12 are filled with working medium through the small passage opening 16 of the hollow cylinder or piston 13. The gas spring piston surface is larger than the piston inner surface, therefore the gas spring force pushes the piston 13 towards the end face into the soft seal 14, i.e., into the closed position, thus closing the radial pressure outlet 15. The DWG is filled. 4. Supply valves 1 and 10 are closed. 5. Open the exhaust valve 9. The driving pressure behind the second actuator element 2 drops and the actuator element is opened by the higher pushing force on the flow passage 7. The driving pressure of the actuator element 6 escapes through the second actuator outlet 4 and the pressure of the working medium in the gas spring chamber 11 pushes the actuator element 6 open (open position) and releases the radial actuator opening 8. 6. The air in the gas spring escapes through the actuator release 8, releasing the gas spring 11. At this time, the piston internal pressure in the interior 12 is greater than the gas spring pressure in the gas spring chamber 11, and the piston 13 moves backward, i.e. to the release position, by the differential force and is released at high speed. As a result, the working medium escapes radially outward from the piston 13 through the pressure outlet 15.

[0061] As the working medium rapidly escapes from the gas spring chamber 11 through the actuator outlet 8 and from the interior 12 through the pressure outlet 15, an intense pressure wave is generated in the surrounding gas. The pressure wave propagates through the environment and cleanses surfaces from contamination when it impinges on them.

[0062] To ensure that the DWG can be operated hand-held, some precautions must be taken as mentioned above, since the recoil of the escaping working medium would tear the DWG from the user's hands. On the other hand, the pressure outlets 15 are arranged opposite each other on the housing 16. The same applies to the actuator outlets 8.

[0063] On the other hand, it is advantageous if a protrusion 20, for example in the form of a rib or a circumferential ring, is mounted adjacent to the pressure outlet 15 on the outside of the housing 16. The outflowing gases with an axial component of flow impinge on the protrusion 20. As mentioned above, the axial recoil of the outflowing working medium on the pressure chambers 11, 12 and the piston 13 and the opposite impact of the working medium on the protrusion 20 at least partially compensate each other. This makes the DWG easier to handle.

[0064] Figure 2 shows a system used in steam boilers, consisting of a DWG 24 and a lance 25 on which the DWG 24 is mounted. A tube bundle 23 with a large number of heat exchange tubes is installed in the convection passage 21 of the steam boiler and covers the entire flow cross section of the boiler. Hot flue gases 22 flow through the tube bundles 23, known for short as "bundles", passing through the heat exchange tubes and transferring their heat to the tubes. The flue gases 22 are often accompanied by combustion products that settle or condense on the bundles 23, so that fouling occurs there, for example in the form of soot and agglomerations. Between each two bundles 23 there is an intermediate space 27, called the passage, which is accessible via a boiler door 28. The length of one side of a square boiler cross section, for example, is typically 3 to 25 m.

[0065] Using the DWG 24 according to the invention, this contamination can be removed. For this purpose, the DWG 24 can be introduced into the passage 27 through the boiler door 28 with the help of the lance 25. Advantageously, the lance 25 is more than 3 m and up to 12 m long so that larger boilers with a side length of up to 25 m, accessible from both sides, can be cleaned. In the passage 27, the DWG 24 generates a strong pressure wave 26 that is ideally directed towards the bundle 23 and the dirt. Due to the optimized manageability mentioned above, the lance 25 can be held by hand even in the "shooting mode". Moreover, in one embodiment, especially of a water-cooled system, it is not even necessary to switch off the hot gas flow 22. Thus, the steam boiler 21 and the bundle 23 can be cleaned during operation.

[0066] FIG. 3 shows an alternative installation of the DWG 32 in a vessel in the form of a boiler 31, for example a downstream steam boiler in a gas-fired combined cycle power plant. The DWG 32 is suspended on a rope 35 in the boiler 31. At the same time, supply lines and control lines for the working medium and actuator medium can also run along the rope 35. The position of the DWG 32 can be controlled via a motor-driven roller 36, on which the rope 35 runs. The control of the position of the DWG 32 and the "shot", i.e. the generation of the pressure wave 33, is preferably performed automatically, for example via a computer-implemented control system 37.

[0067] Another advantageous feature is a camera 34 attached to the DWG 32, which allows to detect particularly soiled areas and estimate the success of the cleaning. It is also conceivable to control the position and the "shots" of the DWG 32 in real time via a computer control unit 37 depending on the images taken by the camera 34.

[0068] Although preferred embodiments of the present invention have been described in this application, it should be noted that the present invention is not limited thereto and may be embodied in other ways within the scope of the claims.

Claims

1. In a pressure wave generator that generates a pressure wave, - a pressure chamber (11, 12) which can be filled with a working medium via a pressure chamber inlet and has at least two pressure outlets (15) arranged opposite each other; an actuator chamber (18) which can be filled with actuator medium via an actuator chamber inlet (3); at least two actuator outlets (8) placed opposite each other and connected to said pressure chambers (11, 12) by passages (7); a closure element (13) in the pressure chamber (11, 12) which in a closed position closes the pressure chamber (11, 12) against the pressure outlet (15) and in an open position allows the working medium to flow through the pressure outlet (15), the closure element (13) being at least partially disposed within the pressure chamber (11, 12) between the passage (7) and the pressure outlet (15); an actuator element (6) in said actuator chamber (18), which in a closed position closes said pressure chambers (11, 12) to said actuator outlet (8) and in an open position allows said working medium to flow through said passage (7) and said actuator outlet (8), and by moving said actuator element (6) from the closed position to the open position during operation by said working medium, said closing element (13) can be moved from the closed position to the open position; A pressure wave generator comprising:

2. 2. The pressure wave generator according to claim 1, wherein the closure element (13), in particular the actuator element (6), can be moved from a closed position to an open position by axial displacement, and the pressure outlet (15) and the actuator outlet (8) are arranged substantially radially outward.

3. 3. A pressure wave generator according to claim 1, wherein the pressure chambers (11, 12) are substantially cylindrical and the closure element (13) comprises a hollow cylinder which is open at one end face and the opposite end face of the hollow cylinder is substantially closed and has a passage opening (17) arranged in particular centrally, through which the interior (12) of the hollow cylinder can be filled with a working medium.

4. 4. The pressure wave generator according to claim 3, wherein the closed end surface of the closing element (13) has an inner surface facing the interior (12), said inner surface being smaller than the opposite outer surface, in particular by at least 5%.

5. 5. A pressure wave generator according to claim 3 or 4, wherein the total open area of ​​the pressure outlet (15) is at least as large as the open end face of the hollow cylinder, in particular at least 20% larger.

6. 6. The pressure wave generator according to claim 1, wherein the pressure chambers (11, 12) are 1.2 to 2 times, in particular 1.4 to 1.7 times larger than the interior (12) of the closure element (13), in particular the interior (12) of the closure element (13) has a volume of 1 to 2 liters and the pressure chambers (11, 12) have a volume of 1.5 to 3 liters and / or in particular the closure element (13) has an outer diameter of 100 mm to 150 mm.

7. 7. A pressure wave generator according to any one of claims 1 to 6, wherein the pressure chambers (11, 12) can be filled with the actuator medium at a pressure of at least 100 bar, in particular at least 200 bar, in particular the actuator chamber (18) can be filled with the actuator medium at a pressure of at least 10 bar.

8. 8. A pressure wave generator according to any one of claims 1 to 7, wherein at least two actuator outlets (8) are oriented essentially in the same way as at least two pressure outlets (15), in particular the actuator outlets (15) are arranged at substantially the same angular position on the pressure wave generator as the pressure outlets (15).

9. 9. A pressure wave generator according to any one of claims 1 to 8, wherein the total open area of ​​the actuator outlet (8) or the passage (7) is smaller than the total open area of ​​the pressure outlet (15), in particular less than half.

10. 10. A pressure wave generator according to any one of claims 1 to 9, wherein at least one protrusion (20) is provided on the outside of the pressure wave generator adjacent to the at least two pressure outlets (15) in the direction of an end face of the pressure wave generator, in particular said protrusion (20) being arranged to influence, in particular to deflect, the flow of the working medium exiting from said pressure outlets (15).

11. Further comprising a second actuator chamber (19) and a second actuator element; said second actuator chamber (19) can be filled with said actuator medium via a second actuator chamber inlet, at least two second actuator outlets (4) are placed opposite each other, said second actuator chamber (19) and said actuator chamber (18) are connected by a second passage (3), in particular by said actuator chamber inlet (3), 11. The pressure wave generator according to claim 1, wherein the second actuator element in the second actuator chamber (19) in a closed position closes the actuator chamber (18) and the second actuator chamber (19) against the second actuator outlet (4) and in an open position allows the actuator medium to flow out through the second passage (3) and the second actuator outlet (4) and is disposed in the second actuator chamber (19) between the second actuator chamber inlet and the second passage (3) and is capable of filling the actuator chamber (18) with the actuator medium via the second actuator chamber (19) and the second actuator chamber inlet.

12. 12. The pressure wave generator according to claim 11, wherein the second actuator chamber (19) and the second actuator element (2) are cylindrical, the second actuator element (2) having a passage opening (5) located in particular centrally.

13. A pressure wave generator according to any one of the preceding claims, wherein the actuator chamber inlet (3) is sealed against the passage (7) by an actuator element (6) which in particular does not have a passage opening.

14. 14. The pressure wave generator according to any one of claims 1 to 13, comprising a controllable exhaust valve (9), in particular for the second actuator chamber inlet, for triggering an exhaust of actuator medium from the actuator chamber (18), in particular from the second actuator chamber (19), in particular the exhaust valve (9) comprising a solenoid valve.

15. A pressure wave generator according to any one of the preceding claims, which can be operated handheld, in particular the pressure wave generator having a weight of at most 12 kg, in particular at most 7 kg.

16. In a system for generating pressure waves, A pressure wave generator (24) according to any one of claims 1 to 15, a lance (25) having a pressure wave generator (24) attached to its distal end; Equipped with The lance (25) comprises a first supply line for a working medium and a second supply line for an actuator medium, In particular, said lance comprises a control line for actuating said discharge valve (9).

17. the lance comprises a multi-chamber hollow profile, an outer chamber of the hollow profile being arranged to supply cooling water and / or cooling air for the pressure wave generator (24) to the distal end of the lance (25), 17. The system according to claim 16, wherein the first and second supply lines, in particular a control line, lead to an inner chamber of the hollow profile.

18. 18. The system according to claim 6 or 17, comprising a camera (34), in particular an IR camera, attached to the pressure wave generator (24, 32), in particular to the end face of the pressure wave generator (24, 32), and arranged to inspect the environment of the pressure wave generator (24, 32).

19. A method for generating pressure waves using a pressure wave generator according to any one of claims 1 to 15 or a system according to any one of claims 16 to 18, comprising the steps of: (a) filling said actuator chamber (18) with a gaseous actuator medium at a pressure greater than 10 bar, in particular less than 50 bar; (b) filling the pressure chambers (11, 12) with a gaseous working medium at a pressure of more than 100 bar, in particular more than 200 bar; (c) moving the actuator element (6) from a closed position to an open position, thereby moving the closure element (13) from the closed position to the open position, thereby releasing pressurized working medium from the pressure chambers (11, 12) via the pressure outlet (15) and the actuator outlet (8); A method comprising:

20. 20. The method according to claim 19, wherein the pressurized working medium is released from the pressure chambers (11, 12) in step (c) with a half-value time of less than 10 ms, in particular less than 6 ms.

21. 21. The method according to claim 19 or 20, wherein the actuator chamber (18) is filled in step (a) via the passage opening (5) in the second actuator element (2) and the second actuator chamber (19).

22. 22. The method according to any one of claims 19 to 21, wherein the working medium, in particular the actuator medium, is air, in particular the pressure chamber (11, 12) is filled with an amount of air having a volume of at least 150 litres, in particular at least 300 litres at 1 bar.

23. 23. The method according to any one of claims 19 to 22, wherein the movement of the actuator element (6) in step (c) is performed by evacuating actuator medium from the actuator chamber (18) via the actuator chamber inlet (3), in particular by evacuating actuator medium from the second actuator chamber (18) via the second actuator chamber inlet by opening a drain valve (9).

24. The method according to any one of claims 19 to 23, further comprising repeating steps (a), (b) and (c) with an interval between pressure waves of up to 10 seconds, in particular up to 5 seconds.

25. Use of a pressure wave generator according to any one of claims 1 to 15, a system according to any one of claims 16 to 18, or a method according to any one of claims 19 to 24 for cleaning dirty vessels, pipes or steam boilers.

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