Detonative cleaning apparatus
View Patent ↗An apparatus and methods are provided for cleaning a surface within a vessel. A vessel wall separates a vessel exterior from a vessel interior and has a wall aperture. An elongate conduit has an upstream first and a downstream second end and is positioned to direct a shock wave from the second end into the vessel interior. A source of fuel and oxidizer is coupled to the conduit to deliver the fuel an oxidizer to the conduit. An initiator is positioned to initiate a reaction of the fuel and oxidizer to produce the shock wave within the conduit for generating the shock wave. A source of purge gas is positioned to introduce the purge gas to the conduit to drive reaction products of the fuel and oxidizer downstream.
1. A method for cleaning a surface within a vessel, the vessel having a wall with an aperture therein, the method comprising:
introducing fuel and oxidizer to a conduit, the introducing comprising:
introducing a first fuel and a first oxidizer forming a first fuel/oxidizer mixture; and
introducing a second fuel and a second oxidizer forming a second fuel/oxidizer mixture, the second mixture being less detonable than the first fuel/oxidizer mixture; initiating a reaction of the fuel and oxidizer so as to cause a shock wave to impinge upon the surface; and
introducing a pressurized purge gas to the conduit.
2. The method of claim 1 performed in a repeated sequential way.
3. The method of claim 1 wherein:
the reaction comprises a deflagration-to-detonation transition.
4. The method of claim 1 wherein:
the purge gas comprises in major portion air.
5. The method of claim 1 wherein:
the purge gas is introduced through a purge gas port in an upstreammost 20% of a flowpath length within the conduit.
6. The method of claim 1 wherein:
the second oxidizer is less oxygen-rich than the first oxidizer; and
the second fuel/oxidizer mixture is introduced as a mixture.
7. The method of claim 1 wherein:
the second fuel/oxidizer mixture provides a slower reaction chemistry than a reaction chemistry of the first fuel/oxidizer mixture.
8. The method of claim 1 wherein:
a major portion of said first fuel/oxidizer mixture is provided before a major portion of said second fuel/oxidizer mixture is provided.
9. The method of claim 1 wherein:
a major portion of said first fuel/oxidizer mixture is provided after a major portion of said second fuel/oxidizer mixture is provided.
10. The method of claim 1 wherein:
the vessel is a coal- or oil-fired furnace.
11. The method of claim 1 wherein:
the surface is of a tube bundle.
12. The method of claim 1 wherein:
a baseline flow of the purge gas is maintained between charge/discharge cycles of the conduit so as to prevent gas and particulate from the vessel from infiltrating upstream and to assist in cooling of the conduit.
13. A method for cleaning a surface within a vessel, the vessel having a wall with an aperture therein, the method comprising:
introducing fuel and oxidizer to a conduit, the introducing comprising:
introducing a first fuel and a first oxidizer forming a first fuel/oxidizer mixture; and
introducing a second fuel and a second oxidizer forming a second fuel/oxidizer mixture, the second mixture being less detonable than the first mixture; and
initiating a reaction of the fuel and oxidizer so as to cause a shock wave to impinge upon the surface.
14. The method of claim 13 wherein:
said introducing the first fuel and the first oxidizer is through one or more associated first ports;
said introducing the second fuel and the second oxidizer is through one or more associated second ports; and
said introducing the first fuel and the first oxidizer fills a volume of the conduit extending beyond the second ports.
15. The method of claim 13 wherein:
said volume is 1–20% of a total volume of the conduit.
16. The method of claim 13 wherein:
said introducing the first fuel and the first oxidizer is through one or more associated first ports; and
said introducing the second fuel and the second oxidizer is through one or more associated second ports, downstream of the first ports.
17. A method for cleaning a surface within a vessel, the vessel having a wall with an aperture therein, the method comprising:
introducing fuel and oxidizer to a conduit, the conduit having an upstream end and a downstream end, the introducing forming:
a first mixture of a first fuel and a first oxidizer; and
a second mixture of a second fuel and a second oxidizer, the second mixture being
downstream of the first mixture and less detonable than the first mixture; and
initiating a reaction of the fuel and oxidizer so as to cause a shock wave to impinge upon the surface.
18. The method of claim 17 wherein:
the second oxidizer is less oxygen-rich than the first oxidizer; and
the first fuel and second fuel are the same.
19. The method of claim 17 wherein:
the fuel and oxidizer fill 100% of the conduit.