Catalyst obstacles for pulse detonation device employed in a detonation device cleaning system   

Abstract: A pulse detonation device includes a body member having an outer wall and an inner wall that defines a pulse detonation zone and a plurality of obstacles extend along the pulse detonation zone. At least a portion of the plurality of obstacles include a combustion catalyst.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to coal burning systems and, more particularly, to catalyst obstacles provided in a pulse detonation device employed in a detonation cleaning system.

Industrial boilers operate by using a heat source to create steam from water or another working fluid, which can then be used to drive a turbine in order to supply power. Conventionally, the heat source is a combustor that burns a fuel in order to generate heat, which is then transferred into the working fluid via a heat exchanger, such as a fluid conducting tube or pipe. Burning fuel may generate residues that often are left behind forming a buildup on surfaces of associated ducting or the heat exchanger. This buildup can lead to performance degradation related to an increase in pressure drop, reduced fuel efficiency, and damage to mechanical components. Performance degradation can eventually lead to costly planned or unplanned outages. Periodic removal or prevention of such buildup maintains the operational efficiency of such boiler systems. In the past, the buildup was removed by directing pressurized steam, water jets, acoustic waves, and mechanical hammering onto the inner surfaces of the combustor or heat exchanger. However, such methods are often times costly and not always effective. More recently, detonative combustion devices are being used to remove the buildup. Detonative combustion devices that burn customer friendly fuels, such as natural gas and propane, tend to require large detonation chamber diameters and lengths, which, in turn, require a relatively large installation footprint. Moreover, in some cases, such detonation devices require oxygen enrichment in order to create the detonations. Flexible fuels, or fuels having a large detonation cell size and high direct initiation energy, such as natural gas and propane, do not burn properly in existing systems without the addition of some amount of oxygen. More specifically, when using flexible fuels in existing detonative combustions devices, flame propagation velocity is less than desired, resulting in little or no cleaning ability for the resulting combustion process.

According to one aspect of the invention, a pulse detonation device includes a body member having an outer wall and an inner wall that defines a pulse detonation zone and a plurality of obstacles extend along the pulse detonation zones. At least a portion of the plurality of obstacles include a combustion catalyst.

According to another aspect of the invention, a detonation cleaning system includes a vessel having an interior chamber, and a pulse detonation device operatively coupled to the vessel and fluidly coupled to the interior chamber. The pulse detonation device includes a body member having an outer wall and an inner wall that defines a pulse detonation zone. A plurality of obstacles extend along at the pulse detonation zone. At least a portion of the plurality of obstacles includes a combustion catalyst.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a top schematic view of an interior chamber of a vessel, shown in the form of an industrial boiler, having a pulse detonation device constructed in accordance with an exemplary embodiment; and

FIG. 2 is a schematic cross-sectional view of the pulse detonation device of FIG. 2.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION

With initial reference to FIG. 1, a detonation cleaning system 1 in accordance with an exemplary embodiment includes a vessel, shown in the form of an industrial boiler is indicated generally at 2. Vessel 2 includes a main body 4 having an outer surface 6 and an inner surface 7 that defines an interior chamber 8. In the embodiment shown, vessel 2 includes a flange 10 that is provided on main body 4. Cleaning system 1 also includes a pulse detonation device 20 operatively connected to flange 10 and, as will become more fully evident below, an air source 23 and a fuel source 24 that are electrically connected to a controller 40. Pulse detonation device 20 is selectively operated to direct a supersonic pulse detonation or shockwave 44 into interior chamber 8 to dislodge or loosen any build-up of debris.

Pulse detonation device 20 includes a body member 83 having a first end or inlet 86 that extends to a second end or outlet 87 through an intermediate portion 89. With this arrangement, controller 40 establishes a desired fuel/air mixture that is passed to inlet 86 of pulse detonation device 20. The fuel air mixture is ignited to form a pulse detonation wave that is directed through transition piece 91 and into interior chamber 8 to loosen debris, such as soot that my be clinging to internal surfaces of vessels 2. Controller 40 is also configured to set a desired frequency of supersonic pulse detonation wave 44 emanating from pulse detonation device 20. Controller 40 can set a frequency of up to about 20 Hz for the pulse detonation wave. The frequency of the pulse detonation wave can be controlled to aid in establishing non-uniform, frequency shifted, waves that cooperate to dislodge the debris. Supersonic pulse detonation wave 44 can reach temperatures up to about 2500° F. (1371.1° C.) degrees or better. The high temperatures and non-uniform shockwaves achievable by the use of a pulse detonation device cooperates to enhance the removal of debris from vessel 2.

In accordance with an exemplary embodiment illustrated in FIG. 2, pulse detonation device 20 includes a central pulse detonation tube 126 arranged within body member 83, and an intermediate pulse detonation tube 128 arranged within body member 83 and about central pulse detonation tube 126. Central pulse detonation tube 126 includes a first end 132 that extends to a second end 133 through an intermediate portion 134 that defines a first pulse detonation zone 135. In the embodiment shown, first end 132 defines a fuel and air inlet 137 coupled to fuel air source 23 and fuel source 24. Intermediate pulse detonation tube 128 includes a first end 146 that extends to a second end 147 through an intermediate portion 148 that defines a second pulse detonation zone 149. Second end 147 of intermediate pulse detonation tube 128 includes a flow redirection zone 152 having a curvilinear surface 154. As will be discussed more fully below, flow redirection zone 152 guides a turbulent combustion wave from first pulse detonation zone 135 toward second pulse detonation zone 149.

Body member 83 of pulse detonation device 20 includes an outer wall 157 and an inner wall 158 that defines a third pulse detonation zone 160. In addition, inlet 86 is shown to include a second flow redirection zone 163 having a curvilinear surface 165. Second flow redirection zone 163 redirects the turbulent combustion wave from second pulse detonation zone 149 toward third pulse detonation zone 160. With this arrangement, pulse detonation device 20 includes a curvilinear flow path that promotes the turbulent combustion wave into a shockwave that is detonated to form supersonic pulse detonation wave 44. The curvilinear flow path enables pulse detonation device 20 to have a short overall length while ensuring a desired detonation of the shockwave.

In order to further promote the shock wave and enhance detonation, a first plurality of obstacles 171 extend along first pulse detonation zone 135. First plurality of obstacles 171 take the form of annular discs and are configured to bend/fold the turbulent combustion wave to help promote the shock wave. In accordance with one aspect of the exemplary embodiment, one or more of the first plurality of obstacles 171 are formed from a combustion catalyst 173 that is configured to aid/promote the detonation of the shockwave. In accordance with another aspect of the exemplary embodiment, one or more of the first plurality of obstacles 171 are coated with combustion catalyst 173. In either case, combustion catalyst 173 includes at least one of a chromium oxide, a cobalt oxide, an iron compound, a copper compound, palladium, platinum, and calcium nitrate. Of course it should be understood that combustion catalyst 173 can be formed from a variety of materials that are configured to catalytically increase combustion.

In further accordance with the exemplary embodiment, a second plurality of obstacles 178 extend along second pulse detonation zone 149. In a manner similar to that described above, second plurality of obstacles 178 take the form of annular discs. In accordance with one aspect of the exemplary embodiment, one or more of the second plurality of obstacles 178 are formed from a combustion catalyst 180 that is configured to aid/promote the detonation of the shockwave. In accordance with another aspect of the exemplary embodiment, one or more of the second plurality of obstacles 178 are coated with combustion catalyst 180. In a manner similar to that described above, combustion catalyst 180 includes at least one of a chromium oxide, a cobalt oxide, an iron compound, a copper compound, palladium, platinum, and calcium nitrate. As note above, combustion catalyst 180 can be formed from a variety of materials that are configured to catalytically increase combustion.

In still further accordance with the exemplary embodiment a third plurality of obstacles 184 extend along third pulse detonation zone 160. In a manner also similar to that described above, third plurality of obstacles 184 take the form of annular discs. In accordance with one aspect of the exemplary embodiment, one or more of the third plurality of obstacles 184 are formed from a combustion catalyst 186 that is configured to aid/promote the detonation of the shockwave. In accordance with another aspect of the exemplary embodiment, one or more of the third plurality of obstacles 184 are coated with catalyst 186. In a manner similar to that described above, catalyst 186 includes at least one of a chromium oxide, a cobalt oxide, an iron compound, a copper compound, palladium, platinum, and calcium nitrate. Also, as note above, combustion catalyst 180 can be formed from a variety of materials that are configured to catalytically increase combustion.

Combustion catalysts 173, 180 and 186 react with the shockwave to promote detonation. The addition of combustion catalysts 173, 180, and 186 to obstacles 171, 178 and 184 respectively allows pulse detonation device 20 to have a much shorter length than currently achievable by existing pulse detonation devices. At this point it should be understood that while described as annular discs, the obstacles can take on a variety of forms. Also, in addition to forming/coating the obstacles with the combustion catalyst, pulse detonation device 20 could also be constructed with one or more of the central pulse detonation tube, the intermediate pulse detonation tube, and the inner wall of the body member being formed from, or coated with, a combustion catalyst. Finally, the particular type, and/or geometry of the pulse detonation device could vary. That is, while shown as a reverse flow pulse detonation device, e.g., a detonation device that includes a curvilinear detonation path, the obstacles could also be employed in detonation devices having a substantially linear detonation path.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.