Method and apparatus for generating a mist

• US 9,004,375 B2
• Filed: 02/25/2005
• Issued: 04/14/2015
• Est. Priority Date: 02/26/2004
• Status: Active Grant

• Current Assignee: Tyco Fire Products LP (Johnson Controls International plc)
• Original Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Inventors: Fenton, Marcus Brian Mayhall, Heathcote, John Gervase Mark, Wallis, Alexander Guy
• Primary Examiner(s): Boeckmann, Jason
• Assistant Examiner(s): CERNOCH, STEVEN MICHAEL
• Application Number:
  US10/590,527
• Publication Number:
  US 20080230632A1
• Time in Patent Office: 3,700 Days
• Field of Search: 239/433, 239/434.5, 239/398, 239/418, 239/11, 239/135, 239/138, 239/427, 239/428.3, 239/428, 239/428.5, 239/431, 239/434, 239/594
• US Class Current: 239/11
• CPC Class Codes: A62C 31/02 Nozzles specially adapted for fire-extinguishing
• CPC Class Codes: B05B 7/0483 with gas and liquid jets intersecting in the mixing chamber
• CPC Class Codes: F23D 11/102 in an internal mixing chamber
• CPC Class Codes: F23D 11/104 intersecting at a sharp angle, e.g. Y-jet atomiser

Abstract

The present invention relates to apparatus and method for generating a mist comprising a conduit having a mixing chamber and an exit; a working fluid inlet in fluid communication with said conduit; a transport nozzle in fluid communication with the said conduit, the transport nozzle adapted to introduce a transport fluid into the mixing chamber; the transport nozzle having an angular orientation and internal geometry such that in use the transport fluid interacts with the working fluid introduced into the mixing chamber through the working fluid inlet to atomize and form a dispersed vapor/droplet flow regime, which is discharged as a mist comprising working fluid droplets, a substantial portion of the droplets having a size less than 20 μm.

Claims

1. An apparatus for generating a mist comprising:

a conduit disposed about a longitudinal axis, the conduit having a mixing chamber and an exit; and

a means for creating a dispersed droplet flow regime in which a substantial portion of the droplets have a size of less than 20 micrometers, said means comprising;

an annular working fluid nozzle in fluid communication with said conduit to introduce a working fluid into the conduit; and

an annular transport fluid nozzle adjacent the annular working fluid nozzle and in fluid communication with the conduit to introduce a transport fluid into the mixing chamber and a knife edge separation between the transport nozzle and the working fluid nozzle;

wherein the transport nozzle includes a convergent divergent portion therein to provide for the generation of high velocity flow of the transport fluid the convergent-divergent portion having a throat region between the convergent and divergent portions, the throat region having a cross-sectional area less than that of the convergent or divergent portions; and

wherein the transport nozzle and conduit have a relative angular orientation at the mixing chamber for the introduction of transport fluid flow from the transport nozzle into working fluid flow from the conduit and for shearing of the working fluid by the transport fluid so that the transport fluid concurrently atomizes and mixes with the working fluid in the passage;

wherein each of the annular working fluid nozzle and the transport fluid nozzle comprise an annular nozzle that circumscribes the conduit.

2. The apparatus of claim 1 comprising a means for creating working fluid droplets having a substantially uniform droplet distribution having droplets with a size less than 20 micrometers.

3. The apparatus of claim 1 comprising a means for creating a substantial portion of the droplets having a cumulative distribution greater than 90%.

4. The apparatus of claim 1 comprising a means for creating a substantial portion of the droplets having a droplet size less than 10 micrometers.

5. The apparatus of claim 1, wherein the mixing chamber includes a converging portion.

6. The apparatus of claim 1, wherein the mixing chamber includes a diverging portion.

7. The apparatus of claim 1, wherein the transport nozzle has an exit area to throat area ratio in the range 1.75 to 15, and has an included alpha-angle substantially equal to or less than 6 degrees for supersonic flow.

8. The apparatus of claim 1, wherein the transport nozzle is oriented at an angle beta of between 0 to 30 degrees.

9. The apparatus of claim 1, wherein the transport nozzle is annular and has a divergent flow pattern at the mixing chamber.

10. The apparatus of claim 9, wherein the transport nozzle has inner and outer surfaces each being substantially frustoconical in shape.

11. The apparatus of claim 1, wherein the working nozzle is positioned nearer to the exit than the transport nozzle.

12. The apparatus of claim 1, wherein the working nozzle has inner and outer surfaces each being substantially frustoconical in shape.

13. The apparatus of claim 1, further including a second transport nozzle being adapted to introduce further transport fluid or a second transport fluid into the mixing chamber.

14. The apparatus of claim 13, wherein the second transport nozzle is positioned nearer to the exit than the transport nozzle.

15. The apparatus of claim 14, wherein the second transport nozzle is positioned nearer to the exit than the working nozzle, such that the working nozzle is located intermediate the two transport nozzles.

16. The apparatus of claim 1, wherein the conduit includes a passage.

17. The apparatus of claim 16, wherein the inner wall of the passage comprises a contoured portion comprising a means to induce turbulence of the working fluid upstream of the transport nozzle.

18. The apparatus of claim 1, wherein the mixing chamber includes an inlet for the introduction of an inlet fluid.

19. The apparatus of claim 1, wherein the mixing chamber is closed upstream of the transport nozzle.

20. The apparatus of claim 1, further including a supplementary nozzle arranged inside the transport nozzle and adapted to introduce further transport fluid or a second transport fluid into the mixing chamber.

21. The apparatus of claim 20, wherein the supplementary nozzle is arranged axially in the mixing chamber.

22. The apparatus of claim 20, wherein the supplementary nozzle extends forward of the transport nozzle.

23. The apparatus of claim 20, wherein the supplementary nozzle is shaped with a convergent-divergent profile to provide supersonic flow of the transport fluid which flows therethrough.

24. The apparatus of claim 1, further including a control means adapted to control one or more of droplet size, droplet distribution, spray cone angle and projection distance.

25. The apparatus of claim 1, further including a control means to control one or more of the flow rate, pressure, velocity, quality, and temperature of the inlet and/or working and/or transport fluids.

26. The apparatus of claim 24, wherein the control means includes means to control the angular orientation and internal geometry of the working and/or transport and/or secondary nozzles.

27. The apparatus of claim 24, wherein the control means includes means to control the internal geometry of at least part of the mixing chamber or exit to vary it between convergent and divergent.

28. The apparatus of claim 1, wherein the exit of the apparatus is provided with a cowl to control the mist.

29. The apparatus of claim 28, wherein the cowl comprises a plurality of separate sections arranged radially, each section adapted to control and re-direct a portion of the discharge of mist emerging from the exit.

30. The apparatus of claim 1, wherein the apparatus for generating a mist is located within a further cowl.

31. The apparatus of claim 1, wherein at least one of the transport, secondary or working nozzles is adapted with a turbulator to enhance turbulence.

32. A spray system comprising the apparatus of claim 1 and transport fluid in the form of steam.

33. The spray system of claim 32, further including working fluid in the form of water.

34. The spray system of claim 32, further including a steam generator and water supply.

35. The spray system of claim 34, wherein the spray system is portable.

36. The apparatus of claim 1, wherein the substantial portion of the droplets that have a size of less than 20 micrometers comprises droplets having a size with 30% or less than a median size of the droplets.

37. A method of generating a mist comprising the steps of:

introducing a flow of transport fluid into a mixing chamber of a conduit through an annular transport nozzle;

introducing a working fluid into the mixing chamber of the conduit through an annular working nozzle, the conduit having an exit disposed about a longitudinal axis;

generating a high velocity flow of the transport fluid by way of a convergent-divergent portion within the transport nozzle, the convergent-divergent portion having a throat region between the convergent and divergent portions, the throat region having a cross-sectional area less than that of the convergent or divergent portions;

orienting the transport nozzle adjacent the working nozzle with a knife edge separation in between such that the high velocity transport fluid flow imparts a shearing force on the working fluid flow; and

atomizing the working fluid and creating a dispersed droplet flow regime of droplets under the shearing action of the working fluid on the transport fluid in which a substantial portion of the droplets have a size less than 20 micrometers;

wherein each of the annular working nozzle and the transport nozzle comprise an annular nozzle that circumscribes the conduit and the conduit circumscribes the longitudinal axis.

38. The method of claim 37, wherein a stream of transport fluid introduced into the mixing chamber is annular.

39. The method of claim 37, wherein the apparatus has an axis and the working nozzle is defined by a working nozzle outer surface facing inward toward the axis and a working nozzle inner surface facing outward away from the axis;

wherein at least part of the working nozzle outer surface converges toward the axis in a direction along the axis toward the mixing chamber.

40. The method of claim 37, wherein the working nozzle circumscribes the transport nozzle.

41. The method of claim 40, wherein an inlet fluid is introduced into the mixing chamber via an inlet of the mixing chamber of the apparatus.

42. The method of claim 37, wherein the method includes the step of introducing the transport fluid into the mixing chamber in a continuous or discontinuous or intermittent or pulsed manner.

43. The method of claim 37, wherein the method includes the step of introducing the transport fluid into the mixing chamber as a supersonic flow.

44. The method of claim 37, wherein the method includes the step of introducing the transport fluid into the mixing chamber as a sub-sonic flow.

45. The method of claim 37, wherein the method includes the step of introducing the working fluid into the mixing chamber in a continuous or discontinuous or intermittent or pulsed manner.

46. The method of claim 37, wherein the mist is controlled by modulating at least one of the following parameters:

the flow rate, pressure, velocity, quality and/or temperature of the transport fluid;

the flow rate, pressure, velocity, quality and/or temperature of the working fluid;

the flow rate, pressure, velocity, quality and/or temperature of the inlet fluid;

the angular orientation of the transport and/or working and/or secondary nozzle(s) of the apparatus;

the internal geometry of the transport and/or working and/or secondary nozzle(s) of the apparatus; and

the internal geometry, length and/or cross section of the mixing chamber.

47. The method of claim 46, wherein the mist is controlled to have a substantial proportion of its droplets having a size less than 10 micrometers.

48. The method of claim 37, including the generation of condensation shocks and/or momentum transfer to provide suction within the apparatus.

49. The method of claim 37, including inducing turbulence of the inlet fluid prior to it being introduced into the mixing chamber.

50. The method of claim 37, including inducing turbulence of the working fluid prior to it being introduced into the mixing chamber.

51. The method of claim 37, including inducing turbulence of the transport fluid prior to it being introduced into the mixing chamber.

52. The method of claim 37, wherein the transport fluid is steam or an air/steam mixture.

53. The method of claim 37, wherein the working fluid is water or a water-based liquid.

54. The method of claim 37, wherein the mist is used for fire suppression.

55. The method of claim 37, wherein the mist is used for decontamination of a room or space.

56. The method of claim 37, wherein the substantial portion of the droplets that have a size of less than 20 micrometers comprises droplets having a size with 30% or less than a median size of the droplets.