METHODS AND APPARATUS FOR DETECTING PARTICLES ENTRAINED IN FLUIDS

• US 20130213115A1
• Filed: 10/28/2011
• Published: 08/22/2013
• Est. Priority Date: 10/29/2010
• Status: Active Grant

• Current Assignee: University of British Columbia
• Original Assignee: University of British Columbia
• Inventors: Chu, Winnie Chu-Hui, Schaap, Allison, Stoeber, Boris
• Granted Patent: US 9,541,475 B2
• Time in Patent Office: Days
• US Class Current: 73/28.04
• CPC Class Codes: B07B 7/00 Selective separation of solid materials carried by, or dispersed in, gas currents sieves or filters for separating dispersed particles from gases or vapours B01D
• CPC Class Codes: G01N 1/28 Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Qmounting specimens on microscopic slides G02B21/34; means for supporting the objects or the materials to be analysed in electron microscopes H01J37/20 ; laboratory gas handling apparatus B01L5/00
• CPC Class Codes: G01N 15/0255 with mechanical, e.g. inertial, classification, and investigation of sorted collections with centrifuges G01N15/042
• CPC Class Codes: G01N 2001/2223 aerosol sampling devices
• CPC Class Codes: G01N 2015/019 Biological contaminants; Fouling

Abstract

Apparatus and methods for size-specific detection of particles entrained in fluids are provided. A particle size selector separates particles entrained in a sample fluid stream using a curved channel. Shroud fluid streams are interposed between the sample fluid stream and walls of the channel. Centrifugal forces arising from fluid flow through the curved channel separate differently-sized particles into different transverse sections of the channel. A detector downstream from the particle size selector specifically detects particles in one or more transverse sections of the channel.

Claims

1. Size-specific particle detection apparatus comprising:

a particle size selector having;

a channel having a curved section,

a sample fluid introduction port upstream of the curved section, and

at least one shroud fluid port upstream of the curved section, the sample fluid introduction port and the at least one shroud fluid port configured to interpose a shroud fluid stream introduced via the at least one shroud fluid port between a sample fluid stream introduced via the sample fluid introduction port and the outside of the curved section; and

a detector configured to detect particles in the channel downstream from a start of the curved section wherein the sample fluid introduction port and the at least one shroud fluid port are configured to interpose a shroud fluid stream introduced via the at least one shroud fluid port between the sample fluid stream introduced via the sample fluid introduction port and the inside of the curved section.

2. Apparatus according to claim 1 wherein the detector is configured to specifically detect particles in a transverse section of the channel.

3. Apparatus according to claim 1 wherein the at least one shroud fluid port comprises an outside shroud fluid port configured to introduce shroud fluid along a side of the channel leading to the outside of the curved section.

4. Apparatus according to claim 3 wherein the outside shroud fluid port is downstream from the sample fluid introduction port.

6. Apparatus according to claim 1 wherein the at least one shroud fluid port comprises an inside shroud fluid port along a side of the channel leading to the inside of the curved section.

7. Apparatus according to claim 6 wherein the inside shroud fluid port is downstream from the sample fluid introduction port.

8. Apparatus according to claim 1 wherein the sample fluid introduction port and the at least one shroud fluid port are configured to interpose a shroud fluid stream introduced via the at least one shroud fluid port between a sample fluid stream introduced via the sample fluid introduction port and a first side of the channel between sides of the channel leading to the outside and inside of the curved section.

9. Apparatus according to claim 8 where the at least one shroud fluid port comprises a first shroud fluid port along the first side of the channel.

10. Apparatus according to claim 9 wherein the sample fluid introduction port is on the first side of the channel and upstream the first shroud fluid port.

11. Apparatus according to claim 10 wherein the at least one shroud fluid port comprises a second shroud fluid port upstream of the sample fluid introduction port.

12. Apparatus according to claim 9 wherein the at least one shroud fluid port comprises a second shroud fluid port on a second side of the channel opposite the first side.

13. Apparatus according to claim 12 wherein the sample fluid introduction port is upstream the second shroud fluid port.

14. Apparatus according to claim 1 comprising a source of pressurized shroud fluid connected to the at least one shroud fluid port.

15. Apparatus according to claim 14 wherein the source of pressurized shroud fluid comprises an air pump and a filter connected to filter air pumped by the air pump.

16. Apparatus according to claim 14 wherein the source of pressurized shroud fluid comprises a source of compressed gas.

17. Apparatus according to claim 1 comprising at least one downstream shroud fluid port downstream of the curved section.

18. Apparatus according to claim 17 wherein the at least one downstream shroud fluid port comprises a downstream outside shroud fluid port along a side of the channel extending from the outside of the curved section.

19. Apparatus according to claim 17 wherein the at least one downstream shroud fluid port comprises a downstream inside shroud fluid port on a side of the channel extending from the inside of the curved section.

20. Apparatus according to claim 17 comprising a source of pressurized shroud fluid connected to the at least one downstream shroud fluid port.

21. Apparatus according to claim 14 wherein the particle size selector comprises a variable valve operable to control flow of shroud fluid from the source of pressurized shroud fluid to the channel.

22. Apparatus according to claim 21 wherein the particle size selector comprises a plurality of variable valves operable to independently control flow of shroud fluid from the source of pressurized shroud fluid through corresponding ones of the at least one shroud fluid port.

23. Apparatus according to claim 1 wherein a transverse width of the channel downstream from the curved section is wider than a transverse width of the channel in the curved section.

24. Apparatus according to claim 1 wherein the channel widens between the start of the curved section and the detector.

25. Apparatus according to claim 1 wherein the detector comprises a filter configured to collect particles entrained in fluid flowing in the channel.

26. Apparatus according to claim 25 wherein at least a portion of the filter is translucent and wherein the detector comprises:

a light source configured to illuminate at least a part of the translucent portion of the filter, and

a light sensor configured to detect light transmitted by the filter.

27. Apparatus according to claim 26 wherein the filter comprises translucent and opaque transverse sections.

28. Apparatus according to claim 26 wherein the light source is configured to illuminate only one or more specific transverse sections of the filter.

29. Apparatus according to claim 26 wherein the light sensor is configured to detect only light transmitted through one or more specific transverse sections of the filter.

30. Apparatus according to claim 1 wherein the detector comprises a light source configured to emit a light beam into the channel and a light detector configured to detect light scattered by particles passing through the light beam.

31. Apparatus according to claim 30 wherein the light source is configured to illuminate only a specific transverse section of the channel.

32. Apparatus according to claim 30 wherein the light sensor is configured to sense only light scattered by particles passing through a specific transverse section of the channel.

33. Apparatus according to claim 1 wherein the channel has a divider downstream of the curved section defining a plurality of sub-channels.

34. Apparatus according to claim 33 wherein the divider is generally parallel to an axis curvature of the curved section.

35. Apparatus according to claim 33 wherein the detector is configured to detect only particles passing in one of the plurality of sub-channels.

36. Apparatus according to claim 33 wherein the divider is configured to separate a portion of fluid flow adjacent a wall of the channel from a remainder of fluid flow in the channel.

37. Apparatus according to claim 36 wherein the divider is generally perpendicular to an axis curvature of the curved section.

38. Apparatus according to claim 33 wherein one of the sub-channels has a second curved section downstream from the divider.

39. Apparatus according to claim 38 wherein a transverse width of the second curved section is greater than a transverse width of the one sub-channel'"'"'s corresponding transverse section of the channel upstream from the divider.

40. Apparatus according to claim 1 wherein the detector is located downstream from a widening of the channel.

41. Apparatus according to claim 1 wherein the particle size selector comprises at least one variable valve operable to control at least one of flow of shroud fluid into the channel and sample fluid into the channel.

42. Apparatus according to claim 41 where in the particle size selector comprises:

a sensor configured to detect at least one of a flow rate and a pressure of fluid in the channel, and

a controller configured to control the variable valve to maintain laminar flow conditions in the channel based at least in part on the detected at least one of the flow rate and the pressure of fluid in the channel.

43. Apparatus according to claim 41 wherein the at least one shroud fluid port comprises:

an outside shroud fluid port along a side of the channel leading to the outside of the curved section, and

an inside shroud fluid port along a side of the channel leading to the inside of the curved section,

and wherein the at least one variable valve comprises a variable shroud control valve operable to control flow of shroud fluid introduced via one of the outside shroud fluid port and the inside shroud fluid port.

44. Apparatus according to claim 43 wherein particle size selector comprises a variable valve operable to control flow of shroud fluid introduced via the other one of the outside shroud fluid port and the inside shroud fluid port.

45. Apparatus according to claim 43 wherein the particle size selector comprises:

a shroud flow sensor configured to detect at least one of a flow rate and a pressure of shroud fluid flow controlled by the variable shroud control valve, and

a controller configured to control the variable shroud control valve based at least in part on the at least one of the flow rate and the pressure of shroud fluid detected by the shroud flow sensor.

46. Apparatus according to claim 45 wherein the controller is configured to control the variable shroud flow valve to steer flow of sample fluid introduced via the sample fluid introduction port to a specific transverse section of the channel.

47. Apparatus according to claim 1 wherein the channel comprises a planar channel.

48. Apparatus according to claim 1 wherein the channel comprises a non-planar channel.

49. Apparatus according to claim 1 wherein the channel has a rectangular cross section.

50. Apparatus according to claim 49 wherein the transverse width of the channel is larger than the vertical dimension of the channel

51. Apparatus according to claim 1 wherein the transverse width of the channel upstream from the curved section is in a range of 200 μ

m±

140 μ

m.

52. Apparatus according to claim 1 wherein the transverse width of the channel upstream from the curved section is less than 1 mm.

53. Apparatus according to claim 1 wherein the hydraulic diameter of the channel upstream from the curved section is at least 100 μ

m.

54. Apparatus according to claim 1 wherein the curved section turns at least 90 degrees.

55. Apparatus according to claim 1 wherein the curved section turns at least 120 degrees.

56. Apparatus according to claim 1 wherein the curved section turns at least 180 degrees.

57. Apparatus according to claim 1 wherein a radius of curvature of the curved section is greater than 1 mm.

58. Apparatus according to claim 1 wherein a radius of curvature of the curved section is less than 5 cm.

59. Apparatus according to claim 1 wherein the height of the channel upstream from the curved section is in a range of 200 μ

m±

140 μ

m.

60. Apparatus according to claim 1 wherein the transverse width of the channel downstream from the curved section is at least 5 times as wide.

106. Portable air quality monitoring apparatus comprising apparatus according to any claim 1.

5. (canceled)

61. A method for separating particles entrained in a sample fluid stream according to particle size, the method comprising:

flowing the sample fluid stream through a curved section of a channel with the sample fluid stream spaced apart from the outside of the curved section by shroud fluid to separate the particles into a plurality of different transverse sections of the channel the method comprising sandwiching the sample fluid stream between streams of shroud fluid upstream from the curved section.

62. (canceled)

63. A method for size-specific detection of particles in a sample fluid stream, the method comprising:

flowing the sample fluid stream through a curved section of a channel with the sample fluid stream spaced apart from the outside of the curved section by shroud fluid to separate the particles into a plurality of different transverse sections of the channel;

detecting particles downstream from the curved section at one or more of the different transverse sections of the channel the method comprising sandwiching the sample fluid stream between streams of shroud fluid upstream from the curved section.

65. A method according to claim 63 comprising interposing a shroud fluid stream between the sample fluid stream and the outside of the curved section.

66. A method according to claim 63 comprising introducing shroud fluid along a side of the channel leading to the outside of the curved section.

67. A method according to claim 63 comprising interposing a shroud fluid stream between the sample fluid stream and the inside of the curved section.

68. A method according to claim 63 comprising introducing shroud fluid along a side of the channel leading to the inside of the curved section.

69. A method according to claim 63 comprising surrounding the flow of sample fluid with shroud fluid upstream of the curved section of the channel.

70. A method according to claim 63 comprising interposing a shroud fluid stream between a first side of the channel between the sides of the channel leading to the outside and inside of the curved section.

71. A method according to claim 63 comprising introducing the sample fluid stream into a stream of shroud fluid.

72. A method according to claim 63 comprising introducing shroud fluid downstream from the curved section to laterally displace fluid flowing in the channel.

73. A method according to claim 63 comprising specifically detecting particles in the one or more transverse sections of the channel.

74. A method according to claim 63 wherein detecting particles downstream from the curve section comprises collecting particles entrained in fluid flowing in the channel with a filter.

75. A method according to claim 74 wherein at least a portion of the filter is translucent and comprising:

illuminating at least part of the translucent portion of the filter; and

detecting light transmitted by the filter.

76. A method according to claim 75 comprising illuminating only one or more specific transverse sections of the filter.

77. A method according to claim 75 comprising detecting only light transmitted through one or more specific transverse sections of the filter.

78. A method according to claim 63 comprising:

emitting light into the channel; and

detecting light scattered by particles passing through the emitted light.

79. A method according to claim 78 comprising illuminating only one or more specific transverse sections of the channel.

80. A method according to claim 78 comprising detecting only light scattered by particles passing through one or more specific transverse sections of the channel.

81. A method according to claim 63 comprising dividing fluid flowing in the channel downstream from the curved section into a plurality of sub-channels.

82. A method according to claim 81 wherein each of the plurality of sub-channels corresponds to a different transverse section of the channel.

83. A method according to claim 81 wherein detecting particles downstream from the curve sections at one or more of the different transverse sections of the channel comprises detecting particles passing in one of the plurality of sub-channels.

84. A method according to claim 81 comprising flowing fluid in one of the plurality of sub-channels through a second curved section.

85. A method according to claim 63 comprising separating a lower velocity portion of fluid flow in the channel from the remainder of fluid flow in the channel.

86. A method according to claim 63 wherein detecting particles downstream from the curved section comprises detecting particles at in an expanded channel section having a transverse width greater than a transverse width of the channel in the curved section.

87. A method according to claim 63 comprising:

detecting at least one of a flow rate and a pressure of fluid in the channel, and

controlling at least one of a flow of shroud fluid and sample fluid into the channel based at least in part on the detected at least one of the flow rate and the pressure of fluid in the channel.

88. A method according to claim 63 comprising:

detecting at least one of a flow rate and a pressure of shroud fluid introduced along a side of the channel leading to the outside of the curved section; and

controlling a flow of shroud fluid introduced along the side of the channel leading to the outside of the curved section based at least in part on the detected at least one of the flow rate and the pressure of fluid introduced along the side of the channel leading to the outside of the curved section.

89. A method according to claim 63 comprising:

detecting at least one of a flow rate and a pressure of shroud fluid introduced along a side of the channel leading to the inside of the curved section; and

controlling a flow of shroud fluid introduced along the side of the channel leading to the inside of the curved section based at least in part on the detected at least one of the flow rate and the pressure of fluid introduced along the side of the channel leading to the inside of the curved section.

90. A method according to claim 63 comprising controlling a flow of shroud fluid introduced along a side of the channel to steer flow of sample fluid to a specific transverse section of the channel.

91. A method according to claim 63 wherein the sample fluid is flowed at a velocity of less than 5 meters per second in the curved section.

92. A method according to claim 63 wherein the sample fluid is flowed at a velocity of more than 0.1 meters per second in the curved section.

93. A method according to claim 63 wherein the sample fluid is flowed at a velocity in a range of 0.5 meters per second to 2 meters per second in the curved section.

94. A method according to claim 63 wherein the sample fluid is flowed at a velocity in a range of 1 meters per second to 1.5 meters per second in the curved section.

95. A method according to claim 63 wherein a ratio of shroud fluid to sample fluid in the channel is at least 2:

1 by volume.

96. A method according to claim 63 wherein a ratio of shroud fluid to sample fluid in the channel is at least 3:

1 by volume.

97. A method according to claim 63 wherein a ratio of shroud fluid to sample fluid in the channel is at least 10:

1 by volume.

98. A method according to claim 63 wherein a ratio of shroud fluid to sample fluid in the channel is at least 100:

1 by volume.

99. A method according to claim 63 wherein the curved section turns at least 90 degrees.

100. A method according to claim 63 wherein the curved section turns at least 120 degrees.

101. A method according to claim 63 wherein the curved section turns at least 180 degrees.

102. A method according to claim 63 wherein the shroud fluid comprises gas.

103. A method according to claim 63 wherein the shroud fluid comprises air.

104. A method according to claim 63 wherein the shroud fluid comprises filtered sample fluid.

64. (canceled)

105. A particle size selector comprising:

a channel having a curved section,

a sample fluid introduction port upstream of the curved section, and

at least one shroud fluid port upstream of the curved section, the sample fluid introduction port and the at least one shroud fluid port configured to interpose a shroud fluid stream introduced via the at least one shroud fluid port between a sample fluid stream introduced via the sample fluid introduction port and the outside of the curved section.

107. (canceled)

108. (canceled)