MX2007002298A - Pulse detonation combustor cleaning device and method of operation - Google Patents

Abstract

A pulse detonation cleaner system is described. The cleaner includes an elongated combustion chamber configured with at least one fuel injection inlet and one air inlet to provide fuel to the combustion chamber. The fuel and air are mixed and ignited using an ignition device to produce a flame. The flame is accelerated into a detonation as it propagates downstream through the combustion chamber. The detonation and its products are vented from the combustion chamber into a vessel to be cleaned. The shock and high-pressure products of the detonation are used to release debris from the walls of the vessel and blow them away.

Description

PULSATION DETONATION COMBUSTER CLEANING DEVICE AND METHOD OF OPERATION CROSS REFERENCE This application claims priority under 35 U. S. C § 1 19 (e) of Provisional Application No. 60 / 763-563 filed on January 31, 2006.

BACKGROUND OF THE INVENTION The systems and techniques described herein are generally related to a cyclic pulsation detonating combustion cleaner. More specifically, they are related to the removal of the accumulation of surfaces in several sections of an industrial boiler system that uses pulses generated by detonations through pulsations. Industrial kettles operate using a heat source to create water vapor or other working fluid, which can later be used to move a turbine in order to supply power. The heat source can be a combustor that burns a fuel in order to generate heat, which is then transferred to the working fluid through a heat exchanger. The burning of fuel can generate residues that can remain on the surface of the combustor or heat exchanger. Such accumulation of soot, ash, slag, or dust on the surfaces of the heat exchanger can inhibit heat transfer and therefore reduce the efficiency of the system. The periodic removal of such accumulated deposits maintains the efficiency of these boiling systems. In the past, pressure steam, water jets, acoustic waves, and mechanical knocking have been used to remove this buildup. These systems can be expensive to maintain and the effectiveness of these devices varies depending on the location and use. More recently, attempts have been made to use detonating combustion devices to remove accumulation. These systems tend to require a large installation area, operate infrequently, and in some cases require oxygen enrichment in order to create detonations. Therefore, there is a continuing need for the development of effective detonating combustion cleaning systems.

BRIEF DESCRIPTION OF THE INVENTION Briefly, in accordance with one aspect of the systems described herein, a system is provided for accumulating accumulated debris from a surface in a container. The system includes a container having a surface to be cleaned, a source of fuel to provide a fuel, an air source to provide an air flow and a pulsation detonation combustor. The combustor includes a combustion chamber having a wall defining an air flow path from an upstream end to a downstream end, an air inlet arranged in the combustion chamber and connected to the air source and in communication of flow with the combustion chamber, a fuel inlet in flow communication with the combustion chamber and connected to the fuel source, an ignition device arranged downstream of the fuel inlet that is configured to periodically ignite the fuel in the flow of air and produce a flame, and a plurality of obstacles disposed along the path of the air flow and configured to promote the acceleration of the flame in a detonation as it passes through the combustion chamber. The downstream end of the pulsation detonation combustor is disposed in the container such that a shock wave associated with the detonation of the pulsation detonation combustor passes over the surface to be cleaned in the container. In accordance with another aspect of the systems described herein, it provides a cleaner for removing accumulated debris from a surface of a container. The cleaner includes a pulsed detonation combustor as described above, and the downstream end of the pulsed detonation combustor is configured to direct the shock wave associated with detonation in the pulsed detonation combustor to pass over the surface of a container that is going to be cleaned.

In accordance with one aspect of the techniques described herein, a method is described for removing accumulated debris from a surface in a container. The methods include the steps of receiving an air flow in a combustion chamber through an air chamber, the air flow defining a downstream flow direction. Another step includes receiving a fuel flow in the combustion chamber through a fuel inlet in the air flow. Other steps include mixing the fuel and air in the combustion chamber and periodically igniting the fuel and air mixture using an ignition device. Another step includes accelerating the flame to a detonation by passing downstream through the combustion chamber by passing the flow over a plurality of obstacles arranged along the path of the air flow through the combustion chamber. Other steps include directing the detonation to a container having a surface to be cleaned and passing the shock wave associated with detonation on a surface in a container to loosen surface debris. The method also includes blowing the loosened remains of the surface.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of the present invention will be better understood when the following detailed description is read with reference to the accompanying drawings in which similar characters represent similar parts throughout the accompanying drawings, wherein: 1 is a schematic representation of a pulsation detonation combustor system in accordance with one aspect of the systems described herein; Fig. 2 is a schematic representation of an alternate head end for a pulsating detonation combustor in accordance with another embodiment of the systems described herein; Figure 3 is a schematic representation of one embodiment of a deflection chamber for use with the pulsation detonation combusers described herein; Figure 4 is a schematic axial view of an annular ring obstacle for use in a pulsation detonation combustor as described herein; Figure 5 is a schematic axial view of a circular segment obstacle for use in a pulsed detonation combustor as described herein; Figure 6 is a schematic axial view of an obstacle of increasing shape for use in a pulsed detonation combustor as described herein; Figure 7 is a schematic representation of an alternate embodiment of a combustion chamber for use in a PDC-based cleaner as described herein; Figure 8 is a schematic axial cross-sectional view of a bolt used as an obstacle in a pulsation detonation combustor as described herein; Fig. 9 is a schematic representation of a curved combustion chamber for use in a pulsation detonation combustor as described herein; Figure 10 is a schematic representation of a PDC-based cleaner that extends into the interior of an example kettle as described herein; Fig. 11 is a multiple output camera for use in a PDC-based mode as described herein; and Figure 12 is an alternating arrangement of a multiple outlet cleaner disposed in an example kettle vessel in accordance with the systems described herein.

DETAILED DESCRIPTION OF THE INVENTION As discussed previously, soot or other build-up on the surfaces of the heat exchanger in industrial kettles can cause losses in the overall efficiency of the system due to a reduction in the amount of heat that is actually transferred to the working fluid. This is often reflected by an increase in the temperature of the exhaust gases from the back of the process, as well as an increase in the speed of fuel burning required to maintain steam production and power generation. Traditionally, the complete removal of the accumulation of such dirty surfaces requires that the kettle be turned off while the cleaning process is being carried out. Online cleaning techniques generally result in high maintenance costs or incomplete cleaning results. In the systems and techniques described herein, a pulse detonation combustor external to the boiler is used to generate a series of detonations or quasi-detonations that are directed toward the soiled portion of the boiler. High-velocity shockwaves travel through the soiled portion of the kettle and loosen the accumulation of the surface, which is then allowed to come out of the kettle through hoppers. As will be discussed further, the use of repeated detonations has advantages over traditional cleaning techniques, such as steam blowers or purely acoustic soot removal devices. It is also desirable that a cleaning system for a kettle be able to operate to rapidly remove accumulations in order to minimize the time of stopping the kettle. Furthermore, it is desirable that the system be conveniently operable in the environment of the kettle, i.e., that it be able to physically accommodate itself in the necessary space constraints, be able to reach the portions of the kettle that require removing the dirt, and that does not interfere with the operation of the kettle when the cleaning system is not in use. It is also desirable that the installation of such a cleaner does not require an excessive flow space outside the boiler or requires major modifications to the boiler to access it. The cleaning system based on the pulsation detonation combustor that can provide these and other features will be described in greater detail below. As used herein, the term "pulsed detonation combustor" (PDC) will refer to a device or system that produces both a rise in pressure and an increase in speed of detonation or near detonation. of a fuel and oxidant, and that can be operated in a repeated mode to produce multiple detonations or near detonations in the device. A "detonation" is a supersonic combustion in which a shock wave is associated to a combustion zone, and the shock is sustained by the release of energy from the combustion zone resulting in combustion products at a higher pressure than the reactants of combustion. For simplicity, the term "detonation" as used herein may mean that it includes detonations and quasi-detonations. A "quasi-detonation" is a supersonic turbulent combustion process that produces a pressure rise and a velocity increase greater than an increase in pressure and the increase in velocity produced by a subsonic deflagration wave. The example PDCs, some of which will be discussed in more detail below, include an ignition device for the ignition combustion of a fuel / oxidant mixture, and a detonation chamber in which the pressure wave fronts initiated by combustion they coalesce to produce a detonation wave. Each detonation or quasi-detonation is initiated either by an external ignition source, such as a spark discharge, laser pulsation, heat source, or plasma ignition device, or by dynamic gas processes such as shock focus, auto-ignition or an existing detonation wave from another source (crossfire ignition). The geometry of the detonation chamber allows the pressure increase behind the detonation wave to direct the detonation wave and also blow the same combustion products out of an escape from the PDC. Various camera geometries can withstand the formation of a detonation, including round cameras, tubes, resonant cavities and ring chambers. Such chambers can be of constant or variable cross section, both in area and in shape. Example chambers include cylindrical tubes and tubes having polygonal cross sections, such as for example hexagonal tubes. As used herein, "downstream" refers to a flow direction of at least the fuel or oxidant. One embodiment of a PDC-based cleaning device suitable for use with an industrial boiler is illustrated schematically in FIG. 1. The PDC cleaner 100 extends along the illustrated x-axis from an upstream header end that includes inputs for air and fuel (102 and 104, respectively) located on the left side of the figure, to an exit opening 116 at the downstream end shown on the right side of the figure. A tube 114 extends from the end of the head to the opening 116, defining a combustion chamber 101 therein. In the illustrated embodiment the opening 16 of the PDC is attached to the wall 149 of the boiler to be cleaned or another downstream component that can be used to improve the cleaning operation, as will be discussed in more detail below. As noted above, the head end of the illustrated PDC includes an air inlet 102. The air inlet 102 can be connected to an air source that can be supplied to the PDC under pressure. This air source is used to fill and purge the combustion chamber 101 and also provides air to serve as an oxidant for combustion of the fuel. In particular embodiments, the supply to the air inlet 102 can be connected to an air source installation such as an air compressor. As will be discussed below with respect to the operation of the PDC, the flow through the air inlet will generally enter the tube 114 and will flow in the length of the combustion chamber 114 and will flow downstream through the opening 116. The air inlet 102 of the illustrated embodiment is connected to a central body 112 which extends along the axis of the tube 114 and into the combustion chamber 101. The central body of the embodiment illustrated is a generally cylindrical tube which is extends from the air inlet 102 and tapers to a downstream opening 109. In addition to the downstream opening 109, the central body 112 also includes one or more holes 108 along its length that allow air to flow through of the central body 112 to enter the upstream end of the chamber 101. These orifices connect the interior of the central body with the annular space formed between the central body and the central portion. Rising above the tube 114. The opening 109 and the holes 108 of the central body 112 allow a directional velocity to be imparted to the air that is fed into the tube 114 through the air inlet 102. Such a directional flow can be used to improve the air flow. turbulence in the injected air and improve mixing of the air with the fuel present in the flow at the head end of the PDC. In order to improve these effects, the holes 108 can be arranged in multiple angular and axial locations around the axis of the central body. In some embodiments, the angle of the holes may be purely radial to the axis of the central body. The flow through the central body also serves to provide cooling to the central body in order to avoid the accumulation of excessive heat that could result in the degradation of the central body. In addition to the air inlet 102, a fuel inlet 104 is disposed at the head end of the PDC cleaner 100 illustrated in Figure 1. The fuel inlet 104 is connected to a fuel supply that will be burned in the fuel chamber. combustion 101. A plenum 106 is connected to the fuel inlet 104. In the illustrated embodiment, the plenum 106 is a cavity that extends around the circumference of the head end of the PDC. A plurality of holes 110 connect the interior of the plenum 106 with the interior of the tube 114, fuel is supplied to the plenum 106 via the fuel inlet 104 and then distributed around the circumference of the PDC where it enters the tube 114 to through the holes 1 10. The holes 110 extend generally radially from the plenum 106 into the annular space between the wall of the tube 114 and the central body 112. The fuel is injected into the chamber 101 and mixed with the flow of air coming through the holes 108 of the central body 112. The mixing of the fuel and the air can be improved by the relative arrangement of the air holes 108 and the holes for fuel 110. For example, when placing the holes for fuel 1 0 in a place such that the fuel is injected in regions of high turbulence generated by the flow through the holes for air 108, fuel and air can be mixed faster, producing a more easily detoonable fuel / air mixture. As in the case of the air holes 108, the fuel holes 110 can be arranged in a variety of axial and circumferential positions. Further, the holes 1 0 may be aligned to extend in a purely radial direction, or they may be axially or circumferentially tilted with respect to the radial direction.The fuel can be supplied to the fuel plenum 106 through the inlet 104 by means of a valve that allows active control when fuel is allowed to enter the PDC. Said valve may be disposed in the inlet 104, or it may be arranged upstream in a supply line that is connected to the fuel inlet. In one embodiment of the system the valve can be a solenoid valve, and can be electronically controlled to open and close in order to regulate the flow of fuel. As seen in Figure 1, an ignition device 130 is arranged near the head of the PDC. In the illustrated embodiment, the ignition device is located along the wall of the tube 114 in an axial position similar to the end of the central body 112. This position allows the fuel and air to come through the orifices 110 and 108 respectively, mix before they flow past the ignition device. As indicated above, the ignition device can take various forms as is known in the art. In particular, the device does not need to produce an immediate detonation in the fuel / air mixture in each mode. However, the ignition device 130 desirably provides a sufficiently robust combustion ignition that allows combustion of the fuel / air mixture can change to a detonation within the chamber 101, as will be discussed below. The ignition device 130 can be connected to a controller in order to operate the ignition device at desired times. Although not illustrated, said controller can be used as is generally known in the art to control the timing and operation of various systems, such as the fuel valve and the ignition source. As used herein, the term controller is not limited only to those integrated circuits generally referred to in the art as a controller, but broadly refers to a processor, a microprocessor, a microcontroller, a programmable logic controller, a specific application integrated circuit. , and other programmable circuits suitable for such purposes. The embodiment of a PDC illustrated in Figure 1 includes a tube 1 14 extending generally along the x-axis from the head end described above to an opening 116 at the downstream end of the tube. The combustion chamber 101 is defined by the walls of the tube, and the combustion of the fuel / air mixture takes place in the chamber 101. In general, the combustion will advance from the ignition device 130 through the mixture found. in the combustion chamber 101. Figure 1 illustrates a cross-section of the tube in the form of a substantially round cylinder having a constant cross-sectional area. Those skilled in the art will recognize that other configurations are possible, as indicated above.

The tube 114 contains several obstacles 120 disposed at various locations along the length of the tube. The obstacles 120 are used to improve combustion by advancing along the pipe 1 4, and to accelerate the combustion front to a detonation or near detonation before the combustion front reaches the opening 116 at the downstream end of the pipe. . The obstacles 120 in the embodiment illustrated in Figure 1 are thermally integrated with the wall of the tube 114. Such thermally integrated obstacles can be created in various ways. For example, obstacles may include features that are carved into the wall, formed integrally with the wall (by casting or forging, for example), or attached to the wall, for example by means of welding. In general, a thermally integrated obstacle or other thermally integrated feature of the wall is in sufficient contact with the wall of the tube that the features or obstacles 120 effectively exchange heat with the wall of the tube 114 to which they are integrated. The tube 114, obstacles 120 and central body 112 can be manufactured using a variety of materials suitable to withstand the temperatures and pressures associated with repeated detonations. Such materials include but are not limited to: Inconel, stainless steel, aluminum and carbon steel. Figure 2 illustrates an alternative head end that could be used with a PDC in another embodiment of a PDC-based cleaner. The head end 200 includes a fuel inlet 104 and the plenum chamber 106 having holes 110 each structured and operating substantially in the same manner as described with respect to the embodiment shown in FIG. 1. However, in FIG. Instead of introducing air through an air inlet which is directly connected to the central body, the head end 200 shown in Figure 2 has air and fuel entering directly into a mixing chamber 215 located upstream of a perforated plate 224. Air inlets 2 0, 212 are used to introduce air flow into the mixing chamber 215 shown in Figure 2. Each air inlet can be connected to an air source, such as with an air inlet 102 in Figure 1 The fuel is also expelled from the holes 110 of the plenum 106 inside the mixing chamber 215. The fuel and air begin to mix in the chamber and mixed 215 before they flow through the holes 225 in the perforated plate 224 that separates the mixing chamber 215 from the combustion chamber 101. When the fuel / air mixture is sent through the holes 225 of the plate 224 , additional turbulence is created in the flow, further improving fuel / air mixing. The fuel / air mixture enters the upstream portion of the combustion chamber 101 after it passes through the perforated plate 224, and flows around a central body 230 that can be mounted on the plate 224. This premix flow it can then be ignited by an ignition device 130, much like that described above with respect to Figure 1. The head end 200 illustrated in Figure 2 can be used in place of the head end features described above. , or with variations the PDC that are described later. Figure 3 shows an embodiment of a divergent chamber that can be connected downstream of a PDC system, such as that shown in Figures 1 and 2, and that would receive the flow of the opening 116 of the combustion chamber 101 of the PDC . In the illustrated embodiment, the divergent chamber 300 is connected directly to the outlet opening 116 of the PDC, and the wall 149 of the downstream device shown in Figure 1 is the upstream wall 149 of the divergent chamber 300. Those experienced in the art will recognize that although the divergent chamber need not be in direct contact with the PDC, it is desirable that the camera 101 of the PDC be in flow communication with the divergent chamber 300. As shown in Figure 3, the example divergent chamber 300 has walls 302 that enclose a flow path 310. The walls illustrated form a horn or bell shape that produces an increase in the cross-sectional area of the flow path 310 of the upstream end (connected to the opening 116) to the downstream outlet 320 of the chamber 300. The cross section that increases as the downstream flow moves increases the volume of fuel and air that can be burned in the PDC cleaner during each combustion cycle. This can be used to increase the penetration and effectiveness of the shock waves produced. The illustrated divergent chamber 300 provides a gradually diverging flow path 310, as opposed to an abrupt change in volume that the flow path would experience if It will vent directly into a larger chamber. This gradual divergence allows the detonation produced by the PDC to be sustained by moving through the divergent flow path 310 of the chamber without causing a knock failure. The internal surfaces of the walls 302 of the illustrated divergent chamber 300 are smooth and substantially circular in cross section normal to the axis of the chamber. Those skilled in the art will appreciate that other forms of cross section are also possible, as well as other axial profiles for the divergent camera. In alternative modes of the divergent chamber, similar obstacles can be arranged as described herein for use in DDT in the PDC chamber 101 in the flow path 310 of the divergent chamber 300. Such obstacles (not shown) can be used to promote the Flame acceleration and DDT as the detonation propagated through the expansion profile of the chamber 300. In a particular mode of the divergent chamber, the chamber was formed of a chamber 300 of 1524 millimeters (60 inches) long circular cross section in which diameter increased approximately 50.8 millimeters (2 inches) on the upstream side to a diameter of approximately 482.6 millimeters (19 inches) at outlet 320. With detonations produced using an ethylene / air mixture in an upstream PDC , the detonations could be maintained at frequencies up to 20 Hz. As indicated above, the cleaning system based on PDC uses the detonations produced by a PDC to loosen debris and coatings that can build up on the walls of a boiler or other device, and then the high pressure flow that follows detonation to help blow loose material off the surface. In operation, the PDC creates a detonation and its associated high pressure flow via a combustion cycle, which is repeated at high frequency. PDCs can often be operated at frequencies of 1-100 Hz. Each combustion cycle generally includes a filling phase, an ignition event, a flame acceleration in the detonation phase, and an evacuation phase. The overall operation of the PDC and the cleaner will be discussed with reference to the appended figures in more detail below. In the following discussion, a single occurrence of a fuel filling phase, a combustion ignition, an acceleration of the flame front to a detonation, and the evacuation and purge of the combustion products will be referred to as a "combustion cycle". or "a detonation cycle". The portion of time in which the cleaning system is active is called "cleaning operation". The time in which the container to be cleaned is actively being used for this purpose will be called "kettle operation". As indicated above, the container to be cleaned need not be part of a kettle, however, for simplicity of reference, the term "kettle operation" will be used to refer to the operation of any device that is being cleaned by the cleaning device. In particular, as will be discussed below, an advantage of the system described herein is that, unlike other detonation cleaning systems, there is no need to turn off the boiler or other device whose container is being cleaned in order to operate the cleaner. Specifically, it is possible that the operation of the cleaner takes place during the operation of the kettle. The cleaner does not have to be operated continuously during the operation of the kettle; however, by providing flexibility to operate the cleaner in a regular cycle during the operation of the kettle, a higher overall level of cleaning can be maintained without significant stops in the operation of the kettle. In the filling phase of the detonation cycle, air and fuel are fed into the PDC. As shown in Figure 1 and as discussed above, air can be introduced via the air inlet 102, and fuel through the fuel inlet 104, after which fuel and air will be mixed as needed. described to form a fuel / air mixture suitable for combustion in the PDC. As more fuel and air are introduced and mixed, the chamber will tend to fill with the fuel / air mixture, beginning near the head end in the illustrated embodiment and proceeding along its length as more fuel and air are introduced. As discussed above, the air can be continuously fed to the PDC through the air inlet 102 during the operation of the cleaner, but it may be desirable to use a valve to control the introduction of fuel into the PDC by means of a controller in some embodiments . In addition, the ability to control the air flow for times when the cleaner is not operating may also be desirable. In an example mode, a controller can track the amount of time that has passed since the opening of a fuel valve and, based on the speed of the air intake to the PDC, can close the fuel valve once it is has added a sufficient amount of fuel for the fuel / air mixture to have filled the desired portion of the combustion chamber 101. After the combustion event, air continues to be introduced into the chamber 101 during the operation of the combustor or cleaner to help purge any combustion products remaining from the previous combustion cycle. In varying modalities, the valve can be used to provide a greater or lesser amount of fuel that would be required to fill the chamber in order to fine-tune the operation of the PDC. Once the valve is closed and the chamber is no longer supplied with fuel, the ignition device 130 is activated. The ignition device 130 can be operated by means of a controller in order to start combustion of the fuel mixture. air inside the chamber 101. If, for example, a spark igniter is used as an ignition device, the controller may send an electric current to the initiator in order to create a spark at the appropriate time. In general, the ignition device introduces sufficient energy into the mixture near the ignition device to form a flame in the fuel / air mixture near the device 130. By consuming this flame the fuel by burning it with the oxidant present in the mixture, the flame will propagate through the mixture in the chamber 101. As the flame propagates through the chamber 101 of the PDC, the flame front will reach the walls of the tube 114 and the obstacles 120 that are disposed within the tube. The interaction of the flame front with the walls of the tube and the obstacles will tend to generate an increase in pressure and temperature inside the chamber. Such an increase in pressure and temperature will tend to raise the rate at which the flame propagates through the chamber and the rate at which energy is released from the fuel / air mixture by combustion at the flame front. This acceleration continues until the rate of combustion rises above what is expected from a normal deflagration process up to a speed that characterizes a quasi-detonation or detonation. This DDT process desirably takes place quickly (in order to sustain a high cycle of operation), and thus the obstacles 120 are used to reduce the starting time and the distance required for each initiated flame to change to a detonation.

The detonation wave descends along the length of the tube 1 14 and out of the outlet opening 116 of the tube. From opening 16, the knock wave can be directed into the body of an object to be cleaned, or it can be sent through a divergent section 300 such as that illustrated in figure 3 before being directed into the object that is going to be cleaned High-pressure combustion products are produced after the detonation wave and are blown through the outlet opening 16 together with the detonation wave itself. As the high pressure products are blown out of the PDC, the continuous supply of air through the air inlet 102 will tend to push the products downstream of the opening 16, even when the pressure in the combustion products drops. Such a continuous air supply is used to purge the combustion products from the tube 1 14. Once the combustion products are purged, the valve for the fuel inlet 104 can be opened, and a new filling phase can be initiated to begin the next combustion cycle. The detonation wave emerging from the tube 1 4 of the divergent chamber 320 includes an abrupt pressure increase, or shock, which will propagate through the body of the object to be cleaned. This shock can have several beneficial effects in the removal of debris and slag from surfaces such as kettle walls. In one aspect, the shock wave can produce pressure waves that travel through the slag and accumulated debris. Such internal pressure waves can produce flexion and compression in the accumulations that can enhance the formation of fractures in the remains and break portions of the rest of the accumulation, or the walls of the kettle. This is often seen as "dust" that is released from the surface of the accumulated slag. In addition, the change in pressure associated with the passage of the shock can produce a bending in the walls of the kettle itself, which helps in the separation of the slag from the walls. In addition, the repeated impacts of subsequent shocks of the repetition of the combustion cycles can excite resonances in the slag that can further improve the internal stresses experienced and promote mechanical rupture of the debris. Behind each crash, the flow of pressurized combustion products provides a sweeping effect that can blow loosened debris and downstream particles. The repeated action of shock and purge is used to erode accumulations accumulated in the walls of kettles. In order to optimize the cleaning effect, the strength of each existing wave of the PDC can be increased or decreased, as can the operational frequency at which the PDC operates. Force and frequency can be adjusted by alterations in both design and operational parameters. For example, changes in the length of the chamber 101 can be used to alter the amount of start time necessary for DDT, or the use of various lengths or shapes of the divergence chamber 300 can be employed in order to achieve different levels of pressure in the shock. Operationally, variations in the amount of fuel filling can be made by controlling the duration that the fuel valve remains open, or the speed or pressure at which air or fuel is introduced into the PDC through the air and fuel inlets 102, 104. By altering the choice of fuel or the operational frequency, the overall operational reliability and cleaning effectiveness can be further refined for the particular geometry or accumulations of residues experienced. In one embodiment of a cleaner as described herein, the fuel used is a gaseous fuel, such as ethylene. In particular embodiments, it should be noted that the fuel does not need to be stored in gaseous form, but may be in gaseous form at the time of entering the combustion chamber 101 through the fuel inlet. Other possible fuels include but are not limited to: other gaseous fuels including hydrogen gas, natural gas, methane, and propane; and liquid fuels including gasoline, kerosene and aviation fuels. For example, experiments were carried out up to 20 Hz using an embodiment with a head end 200 as shown in Figure 2 by burning within a tube 114 as shown in Figure 1. Ethylene was used as fuel and air as oxidant The test results showed that the pressure measured downstream (as would be experienced inside a kettle that is cleaned) was strongly dependent on the duration of the filling phase, and the effective volume of the filling chamber 101 that was filled. By varying the effective fuel fill length of the chamber between approximately 508 millimeters (20 inches) from the inlet to approximately 2.29 meters (90 inches) from the inlet it created a significant variation in the maximum pressure measured downstream during the operation of the PDC . In addition to variations in fuel, oxidant salt variations were also used. Although the term "air" is used throughout the present, those skilled in the art will understand that an appropriate fuel mixture can be formed by the use of oxidants other than air. In a particular embodiment, air is used as an oxidant because it is generally convenient available and avoids the expense and complication of providing a separate oxidant supply. In addition, the use of air allows the continuous purging of the PDC cleaner to more effectively cool the system between combustion cycles. Furthermore, the described systems are capable of operating in such a way that detonations can occur with the use of the same oxidant, such as air, for the initial ignition of the combustion inside the chamber. As well as the start of combustion in a detonation, and the support of the detonation itself. This allows for a simpler system that does not require separate sources of oxidant, or injection of the oxidant at different pressures or concentrations within the combustion chamber at several points.

Similarly, the use of a single-fuel system for both initial combustion, starting, and detonation, allows for a simpler system than one that utilizes fuel supply separate from the various portions of the system (for example, a fuel system). supply of fuel for initial combustion and start-up, and a second fuel supply system for a main detonation chamber). In addition to the use of the same fuel supply system, the systems described here make use of the same fuel for initiation, starting and detonation. It will be understood that other alterations can be made to aspects of the systems and operational methods described while preserving the benefits shown. For example, in an alternative aspect, multiple air inlets 102 may be used in order to allow a more rapid introduction of air into the PDC. In other alternative aspects, multiple fuel inlets 104 can be used, either by feeding a single fuel plenum 106, or by feeding separate plenums that independently inject fuel into the combustion chamber 101 or the mixing chamber 215. Other variations Additional possibilities include the use of multiple ignition devices 130, spaced radially or axially along the head end or the combustion chamber 101. Another example of variation can be found in the configuration of the obstacles 120 discussed above with respect to the figure 1. Obstacles can be in several suitable ways to improve the DDT process and operate reliably in the PDC environment. In one aspect, the obstacles 120 may take the form of annular rings 410 extending from the walls 114 of the tube, as shown in Figure 4. Such rings provide a restriction in the cross-sectional area of the tube, and a surface so that the flame front is reflected from it. Other shapes may include partial obstructions, such as circular segments 420, for example a half moon as shown in Figure 5, or plates of increasing shape 430 as shown in Figure 6. Such shapes may be plates extending from the tube surface 14. The spacing and placement of obstacles 120 may also vary in order to produce more effective cleaning detonations of the PDC. For example, instead of being spaced equally as shown in Figure 1, obstacles 120 can be placed with several distances between successive obstacles 120 along the length of tube 114. In addition, for obstacles such as circular segment 420, 430, or other obstacles that are not rotationally symmetric about the axis of the tube 1 14, variable circumferential fittings are possible. For example, obstacles 120 with a circular segment shape 420 can be placed on alternating sides of tube 114 along the length, such that successive obstacles 120 are disposed opposite each other as shown in Figure 7. In addition , the placement of multiple obstacles in the same axial position along the tube 114 is also possible for obstacles that do not cover the entire area of the tube. An example of such multi-segment placement is shown on the right side of Figure 7. In another embodiment, the obstacles take the form of a cylindrical protrusion extending from the wall of the tube into the combustion chamber. As shown in the axial cross-sectional view of Figure 8, a hole 440 is created in the tube 114 of the PDC. A cylinder 450 is then placed through the orifice 440 and extends through the wall of the tube 114 and into the combustion chamber 101. In one embodiment, the cylinder 450 is threaded, like the orifice 440, and the The cylinder is held in place by the thread between the cylindrical bolt and the hole. In other embodiments, the protrusion is secured in its position by welding or other mechanical restraint. It will be understood that the cylindrical protuberance can also be formed via cast iron or formed integrally with the wall of the tube. Such an arrangement can be used to thermally integrate the bolts with the tube wall 114 as discussed above. As shown in figure 8, the cylinder 450 extends inside the combustion chamber 101. The length in which the cylinder extends into the chamber may vary in different embodiments of the systems described herein. For example, in one embodiment, the length may be greater than or equal to about half the internal diameter of the combustion chamber. In another embodiment, the length may be equal to the internal diameter of the combustion chamber, in which case, the cylinder will extend to the opposite side of the chamber on the side from which it extends. In varying embodiments, the ratio of the length in which the cylinder extends from the wall of the chamber to the internal diameter of the combustion chamber at the site of the cylinder may be: from about 0.5 to about 0.625; from about 0.625 to about 0.70; from about 0.70 to about 0.80; from about 0.80 to about 0.875; from about 0.875 to about 0.95; or from 0.95 to about 1. In a particular embodiment, the cylinder may have an extension length of approximately 38.1 millimeters (approximately 1.5 inches), and the internal diameter may be approximately 50.8 millimeters (2.0 inches), for a length ratio of approximately 0.75. Other modalities will be described below. As can be seen with reference to Figure 8, the cylinder 450 also has a width, or diameter, which may vary in different embodiments of the systems described herein. For example, in one embodiment, the width of the cylinder 450 may be greater than or equal to about one quarter of the internal diameter of the combustion chamber 101. In another embodiment, the width may be less than or equal to one-half the internal diameter . In varying embodiments, the ratio of the width of the cylinder to the internal diameter of the combustion chamber at the cylinder site can be: from about 0.25 to about 0.30; from about 0.30 to about 0.40; from about 0.40 to about 0.45; and from about 0.45 to about 0.5. In a particular embodiment, the cylinder may have a width of approximately 15.9 millimeters (approximately 0.625 inches), and the combustion chamber may have an internal diameter of approximately 50.8 millimeters (approximately 2.0 inches), for a ratio between the width of the cylinder and the internal diameter of approximately 0.3125. Other modalities will be described below. Here and throughout the specification and the claims, range limitations such as those mentioned above may be combined and / or interchanged and such identified ranges may include all secondary ranges contained therein unless the context or language Indicate something else. In another particular embodiment, the DDT portion of the tube 114 is made of a steel tube with an outer diameter of approximately 50.8 millimeters (2 inches) with a length of (1, 02 meters) 40 inches between the end ignition device of head 130 and exit aperture 116. Obstacles 120 were placed approximately every 50.8 millimeters (2 inches) along the length of the DT section, and each obstacle was a threaded pin 450 of approximately 12.7 millimeters (0.5 inches) ) diameter directed through an orifice 440 in the wall of the tube 1 14 and protruding at approximately 31.75 millimeters (1.25 inches) inside the combustion chamber 101. Each bolt 450 was located circumferentially at a position of approximately 90 degrees from the pin arranged immediately upstream, creating a spiral configuration of pins extending along the length of tube 114. In tests, it was found that The use of cylindrical protuberances, such as bolts, provided a high degree of robustness of operational parameters that could be used to withstand detonation. For example, the use of bolts allowed the variation in the overall fuel / air ratio that was present in the combustion chamber at the time of ignition, still allowing the combustion to change to detonation. Such variations in the fuel / air ratio can be achieved by varying the duration of the fuel fill used before each ignition, thus varying the fraction of the overall chamber that is filled with fuel. Such variations can also be achieved by changing the speed at which air or fuel is introduced into the system. During the operation of a PDC, the heat and pressure produced within the combustion chamber can have a damaging effect on the surface of the combustion chamber 101. In particular, obstacles 120 that extend into the flow can be significantly heated during combustion. Having thermally integrated obstacles helps in the transfer of heat from the obstacles to the interior of the tube 114. Because the tube is only heated from one side, and can also be cooled externally, the tube 114 can be used as a heat sink to dissipate heat that is transferred to thermally integrated obstacles 120. Such thermally integrated obstacles will remain colder during the operation and will therefore remain stronger and less prone to failure than non-thermally integrated obstacles. In addition to assisting in the transition from deflagration to detonation in the combustion chamber, obstacles 120 in the form of bolts 450 as shown in Figure 8 can also be removed from tube 114 and replaced if damaged by extended operation. Because such a removable obstacle can be replaced before failure, degradation of PDC performance can be avoided without the need to replace all sections of the PDC tube 114. In addition to the configurations discussed here, other configurations and arrangements of the illustrated components can be used. in the creation of appropriate cleaning systems based on PDC. For example, although the tube 114 is illustrated as extending substantially linearly along the X-axis in Figure 1, in an alternative embodiment, such as that shown in Figure 9, the tube could contain a curvature 510 a The lake of its length separating a first section 520 of the tube from a second section 530 of the tube. In such an arrangement, the second section 530 is not coaxial with the first section 520. Such an arrangement may include obstacles 120 arranged in one or more of the first section 520, the second section 530 and the curvature 530. This configuration creates a combustion chamber 101 extending along the curved path of the tube from the head end to the outlet opening 116. As with the straight tubes, the PDC modes with curvatures 530 can optionally be connected to diverging chambers 300 or other running components. below, or they can go directly to the device that is going to be cleaned. In another embodiment, a curvature may be located in a divergent chamber, such that the divergent chamber is divided into a first section and a second section that are not coaxial. As discussed above with respect to Figure 9, such arrangements may include obstacles in one or more of the first section of the divergent chamber, the second section of the divergent chamber, or the curvature of the divergent chamber. In addition, the curvature itself may be of a divergent cross-sectional area. In still other embodiments, a curvature may be placed between the PDC and one or more downstream devices. For example, in a particular embodiment, a curvature may be arranged between the opening 116 of a combustion chamber and a divergent chamber 300. In addition to providing more flexibility in the package of components of PDC cleaning systems, the curvatures throughout The length of the flow path can provide dynamic benefits of the gas in maintaining the force and development of a detonation wave as it passes through such a curved flow path. In another alternate configuration, a portion of the PDC cleaner may be disposed in the container to be cleaned. For example, Figure 10 illustrates a schematic view of a PDC cleaner having a straight tube 1 14 which is connected to a divergent chamber 300. However, the location of the outlet 320 of the divergent chamber placed flush with the wall 610 of an exemplary kettle 600, a portion of the divergent chamber is disposed within the boiler 600 in such a manner that the divergent chamber 300 extends fura of the wall 610. Another alternate configuration of a Downstream device for use with the PDC cleaners described herein is shown in Figure 11. A multi-output camera 650 is illustrated schematically. Said chamber 650 is formed of the walls 660 which extend inside the container to be cleaned 600 outside the wall 610 of the container itself. The flow of the PDC is directed to the multi-outlet chamber 650 through a hole in the wall 610 of the container. A plurality of holes 670 are disposed in the walls 660 of the chamber 650 through which the knock wave and the pressurized flow of the PDC can be directed into the container 600. Such an arrangement can be used to direct more particularly and locate the output of the PDC for more effective cleaning of specific surfaces inside the container. In the illustrated mode, the multi-outlet chamber 650 extends inside the container 600 from a wall 610 on the side of the container. However, in other embodiments, the multiple outlet tube could be arranged along a wall 610 of the container such that the holes 670 are used to direct the detonations of the PDC at multiple locations along the wall, as shown in FIG. shows in figure 12.

It will also be appreciated that such cleaning systems are not limited to industrial kettles, but can be used to provide cleaning on a variety of different surfaces that may experience fouling. Examples of containers having surfaces that can be cleaned using the systems and techniques described herein include but are not limited to; containers used in the production of cement, energy waste plants, and energy installations by burning of coal, as well as reactors in coal gasification plants. Other features that can be used in variable embodiments of the systems described herein include area reduction devices that can be arranged within the combustion chamber 101 or downstream devices such as the divergent chamber 300 or the multi-outlet chamber 650. Such Area reducing devices may include but are not limited to nozzles and venturis, and may be used to increase pressure in the various chambers or to reflect shocks in order to improve the transition of detonation and propagation. Such devices can be formed integrally with the walls of the chamber, for example, by machining, or they can be attached to the chambers by means of techniques such as friction adjustment, bolting or welding. In addition to varying the configuration of the cleaner, as described above, the duration and frequency of the combustion cycles and the operation of the cleaner may also vary. For example, in a particular embodiment, the cleaner can be activated for approximately 2 seconds during each minute of operation of the kettle. During these two seconds of operation, the cleaner can operate a detonation cycle frequency of about 2 Hz. In said system, a number of small detonations are used for a short period of time each minute to loosen the accumulated debris by agitation. In another embodiment, the operation of the cleaner is used for about one minute. Followed by one minute of no operation in order to allow the cleaner to cool. Said cycle of one minute on and one minute off of the operation of the cleaner is repeated for a period of time, such as 30 minutes. This operation can be executed once per day, or as needed during the continuous operation of the boiler. The frequency of the detonation cycle can be set at 2 Hz, as in the previous example, or it can be increased or decreased as desired. Those skilled in the art will recognize that a variety of configurations of cleaner operating work cycles are possible, making use of a variety of detonation cycle frequencies, without deviating from the present teachings. In a particular embodiment, the cleaner combustor is operated at a frequency greater than or equal to about 1 Hz. In another embodiment, the frequency of the knocking cycle is less than or equal to about 100 Hz. In varying modes, the frequency of the Detonation cycle can be: from about 1 Hz to about 1.5 Hz; from about 1.5 Hz to about 2.5 Hz; from about 2.5 Hz to about 4 Hz; from about 4 Hz to about 8 Hz; from about 8 Hz to about 12 Hz; from about 12 Hz to about 18 Hz; from about 18 Hz to about 25 approximately; from about 25 Hz to about 40 Hz; and from about 40 Hz to about 100 Hz. In particular embodiments, the knocking frequency is: about 2 Hz; of about 3 Hz; of approximately 10 Hz; and about 20 Hz. The various embodiments of the cleaning systems described above provide a way to achieve the removal of soot or ash from a kettle or other container. These techniques and systems also allow periodic operation without the need to turn off the device that is being cleaned for long periods of time. Of courseIt will be understood that all those objects or advantages described above can not necessarily be achieved in accordance with any particular embodiment. Therefore, those skilled in the art will recognize that the systems and techniques described herein may be formed or carried out in a manner that achieves or optimizes an advantage or group of advantages as taught herein without necessarily attaining other advantages. objects or advantages as they may be taught or suggested in the present. In addition, the experienced person will recognize the ability to exchange several characteristics of the different modalities. For example, the use of bolts as described obstacles with respect to one embodiment may be adapted for use with divergent chambers described with respect to another. Similarly, the various features described, as well as other equivalents of each feature, can be combined and fulfilled by someone skilled in the art to build additional systems and techniques with principles of the present disclosure. Although the present systems have been described in the context of certain preferred embodiments and examples, those skilled in the art will understand that the invention extends beyond the modalities specifically described to other alternative embodiments and / or uses of the systems. and techniques of the present and obvious and equivalent modifications thereof. Therefore, it is intended that the scope of the invention described not be limited by the particular embodiments presented described above, but should be determined only by a fair reading of the following claims.

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. - A system for removing accumulated debris from a surface in a container, the system comprising: a container having a surface to be cleaned; a fuel source that provides a fuel; an air source that provides an air flow; a pulse detonating combustor (100), comprising: a combustion chamber (101) having a wall defining an air flow path from an upstream end to a downstream end; an air inlet (102) disposed in the combustion chamber (101) and connected to the air source and in flow communication with the combustion chamber (101); a fuel inlet (104) in flow communication with the combustion chamber (101) and connected to the fuel source; an ignition device (130) disposed downstream of the fuel inlet (104) which is configured to periodically ignite the fuel in the air flow and produce a flame; and a plurality of obstacles (120) disposed along the air flow path and configured to promote acceleration of the flame to a detonation as it passes through the combustion chamber (101); wherein the downstream end (109) of the pulsation detonation combustor (100) is disposed in the container such that the shock wave associated with the detonation of the pulsation detonation combustor passes over the surface to be cleaned in the recipient.

2. - The system according to claim 1, further characterized in that the container is part of a device that keeps in operation during the operation of the combustor (00).

3. - The system according to claim 1, further characterized in that a plenum chamber (106) is arranged in flow communication with the fuel inlet (104), the fuel plenum (106) has a plurality of holes ( 10) that allow the fuel to be injected into the detonation combustor by pulsations (100) through the plurality of holes.

4. - The system according to claim 1, further characterized in that the air inlet (102) is in flow communication with an interior of a hollow central body (1 2) that extends along an axis of the combustion chamber (101), the central body (1 12) has a plurality of holes (108) that provide flow communication between the interior of the central body (1 12) and the combustion chamber (101).

5. - The system according to claim 1, further characterized in that the air source provides a continuous supply of air to the combustion chamber (101) through the air inlet (102) during the operation of the combustor (100). ).

6. - The system according to claim 1, further characterized in that the fuel passing through the fuel inlet (104) is in gaseous form.

7. - A cleaner for removing accumulated debris from a surface of a container, the cleaner comprises: a pulsed detonation combustor (100), comprising: a combustion chamber (101) having a wall defining an air flow path from an upstream end to a downstream end; an air intake (102) in flow communication with the combustion chamber (101) and configured to connect to an air source; a fuel inlet (104) in flow communication with the combustion chamber (101) and configured to connect to a fuel source; an ignition device (130) disposed downstream of the fuel inlet (104) which is configured to periodically ignite the fuel in the air flow and produce a flame; and a plurality of obstacles (120) disposed along the air flow path and configured to promote acceleration of the flame to a detonation as it passes through the combustion chamber (101); wherein the downstream end of the pulsation detonation combustor (100) is configured to direct the shock wave associated with detonation in the pulsation detonation combustor to pass over the surface of a container to be cleaned.

8. - A method for removing accumulated debris from a surface in a container, the method comprising: receiving an air flow in a combustion chamber (101) through an air inlet (102), the air flow defines a direction of downstream flow; receiving a fuel flow within the combustion chamber (101) through the fuel inlet (104) in the air flow; mix the fuel and the air in the combustion chamber (101); periodically igniting the fuel and air mixture using an ignition device (130); accelerating the flame towards a detonation by passing downstream through the combustion chamber (101) passing the flow over a plurality of obstacles (102) arranged along the path of the air flow through the combustion chamber ( 101); directing the detonation inside a container having a surface to be cleaned; passing the shock wave associated with detonation on a surface within a container to loosen surface debris; and blowing the loosened remains of the surface.

9. - The method according to claim 8, further characterized in that the container is part of a device and the device is in operation during the execution of the method.

10. - The method according to claim 8, further characterized in that the steps of the method are repeated at a frequency greater than about 1 Hz.