Industrial bag house elements

• US 6,740,142 B2
• Filed: 05/31/2001
• Issued: 05/25/2004
• Est. Priority Date: 09/05/2000
• Status: Expired due to Term

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Leblanc, James A., Buettner, John M., Gogins, Mark A., Weik, Thomas M.
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): Greene, Jason M.
• Application Number:
  US09/871,006
• Publication Number:
  US 20020073849A1
• Time in Patent Office: 1,090 Days
• Field of Search: 554/82, 554/86, 554/87, 555/27, 555/28, 553/411, 553/82, 553/04, 55D/IG.2, 553/01, 553/02, 952/73, 952/78, 952/80, 952/82, 442/36, 156/60, 156/196, 156/204, 156/227, 156/250, 156/251
• US Class Current: 95/273
• CPC Class Codes: B01D 2273/30 Means for generating a circulation of a fluid in a filtration system, e.g. using a pump or a fan
• CPC Class Codes: B01D 2275/208 Oval shape
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 46/0005 Mounting of filtering elements within casings, housings or frames B01D46/2422 takes precedence
• CPC Class Codes: B01D 46/04 Cleaning filters
• CPC Class Codes: B01D 46/2411 Filter cartridges
• CPC Class Codes: B01D 46/521 using folded, pleated material
• CPC Class Codes: B01D 46/71 with pressurised gas, e.g. pulsed air
• CPC Class Codes: B01D 50/20 Combinations of devices covered by groups B01D45/00 and B01D46/00
• CPC Class Codes: D01F 6/90 of polyamides
• CPC Class Codes: D01F 6/92 of polyesters
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 156/1015 Folding
• CPC Class Codes: Y10T 156/1051 by folding
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing

Abstract

The filter structures commonly known as a bag house or a filter bag or an air filter with a bag construction can be made by preparing the bag assembly, either in a tubular or a bi-fold construction by placing a layer of fine fiber on the upstream surface of the filter media structure. The filter assembly includes a filter cabinet with an interior component. The filter component is suspended within the filter cabinet interior. The filter component includes a frame or support for the filter media. The frame or support holds the filter bags such that the filter bags are suspended from the frame in the cabinet interior. The intake air enters the cabinet, passes through the filter assembly and exits the cabinet. The air must pass first into the fine fiber layer, the filter media and then the exterior of the cabinet.

Claims

1. A filter assembly comprising a filter house having an inlet and an outlet that can pass a gaseous medium, a frame within the filter housing capable of dividing the housing into a first section and a second section, a series of flexible filter bags, each bag configured for treating industrial effluent or off-gas, each bag comprising a filter fabric substrate comprising an elongated filter surface, the frame comprising sealing means connecting the flexible bags to the frame ensuring tat the gaseous medium passes through the flexible filter bag within the housing;

associated with each said flexible bag, support means to prevent the bags from collapsing under the influence of the gaseous stream moving through the housing and means, in a section of the housing, to pass a gaseous stream through the housing and through the flexible bags;

wherein each flexible bag is at least partially covered by a layer having a basis weight of 0.0005 to 0.2 mg-cm<sup>−

2</sup> and a thickness of 0.1 to 3 microns comprising a polymeric fine fiber with a diameter of about 0.01 to about 0.5 micron.

2. The assembly of claim 1 wherein after test exposure for a test period of 16 hours to test conditions of 140°

F. air and a relative humidity of 100%, the assembly retains greater than 30% of the fiber unchanged for filtration purposes.

3. The assembly of claim 1 wherein the polymer comprises an addition polymer.

4. The assembly of claim 1 wherein the polymer comprises a condensation polymer.

5. The assembly of claim 3 wherein to polymer comprises an addition polymer and an additive that forms a coating on the fiber.

6. The assembly of claim 4 wherein the polymer comprises a condensation polymer and an additive that forms a coating on the fiber.

7. The assembly of claim 5 wherein the additive is hydrophobic.

8. The assembly of claim 6 wherein the additive is hydrophobic.

9. The assembly of claim 3 wherein the addition polymer comprises a polyvinyl halide polymer.

10. The assembly of claim 3 wherein the addition polymer comprises a polyvinylidene halide polymer.

11. The assembly of claim 10 wherein the polyvinylidene halide comprises polyvinylidene chloride.

12. The assembly of claim 10 wherein the polyvinylidene halide comprises a polyvinylidene fluoride.

13. The assembly of claim 2 wherein the addition polymer comprises a polyvinylalcohol.

14. The assembly of claim 13 wherein the addition polymer comprises a copolymer.

15. The assembly of claim 13 wherein the polyvinylalcohol is crosslinked with about 1 to 40 wt. % of a crosslinking agent.

16. The assembly of claim 15 wherein the crosslinked polyvinylalcohol is crosslinked using a polyacrylic acid having a molecular weight of about 1000 to 3000.

17. The assembly of claim 15 wherein the crosslinked polyvinylalcohol is crosslinked using a melamine-formaldehyde resin having a molecular weight of about 1000 to 3000.

18. The assembly of claim 4 wherein the condensation polymer comprises a nylon and an additive and the additive forms a coating on the fiber with hydrophobic properties.

19. The assembly of claim 18 wherein the additive comprises a resinous oligomer having a molecular weight of about 500 to 3000 and an aromatic character wherein the additive is miscible in thy condensation polymer.

20. The assembly of claim 18 wherein the nylon comprises a polymer, other than a copolymer formed from a cyclic lactam and a C_6-10 diamine monomer or a C_6-10 diacid monomer, and an additive.

21. The assembly of claim 20 wherein the additive comprises a resinous composition comprising an oligomer having a molecular weight of about 500 to 3000 and an alkyl phenolic aromatic character wherein the additive miscible in the condensation polymer.

22. The assembly of claim 4 wherein the condensation polymer comprises a polyalkylene terephthalate.

23. The assembly of claim 4 wherein the condensation polymer comprises a polyalkylene naphthalate.

24. The assembly of claim 4 wherein the condensation polymer comprises a nylon polymer comprising a homopolymer having repeating units derived from a cyclic lactam.

25. The assembly of claim 24 wherein the nylon polymer is combined with a second nylon polymer, the second nylon polymer differing in molecular weight or monomer composition.

26. The assembly of claim 18 wherein the nylon polymer is combined with a second nylon polymer.

27. The assembly of claim 26 wherein the second nylon polymer comprises an alkoxy alkyl modified polyamide.

28. The assembly of claim 26 wherein the polymers are treated to form a single polymeric composition as measured by a differential scanning calorimeter showing a single phase material.

29. The assembly of claim 28 wherein the polymer and the second polymer are heat treated.

30. The assembly of claim 29 wherein the copolymer and the second polymer are heat treated to a temperature less than the lower melting point of the first or the second polymers.

31. The assembly of claim 6 wherein the additive comprises an oligomer comprising tertiary butyl phenol.

32. The assembly of claim 6 wherein the additive comprises an oligomer comprising bis-phenol A.

33. The assembly of claim 6 wherein the additive comprises an oligomer comprising dihydroxy biphenyl.

34. The assembly of claim 6 wherein the additive comprises a blend of the resinous additive and a fluoropolymer.

35. The assembly of claim 6 wherein the additive comprises a fluorocarbon surfactant.

36. The assembly of claim 6 wherein the additive comprises a nonionic surfactant.

37. The assembly of claim 4 wherein the condensation polymer comprises a polyurethane polymer.

38. The assembly of claim 4 wherein the condemnation polymer comprises a blend of a polyurethane polymer and a polyamide polymer.

39. The assembly of claim 38 wherein the polyamide polymer comprises a nylon.

40. The assembly of claim 18 wherein the nylon comprises a nylon homopolymer, a nylon copolymer or mixtures thereof.

41. The assembly of claim 4 wherein the condensation polymer comprises an aromatic polyamide.

42. The assembly of claim 4 wherein the condensation polymer comprises a reaction product of a diamine monomer and poly(m-phenylene isophthalamide).

43. The assembly of claim 41 wherein the polyamide comprises a reaction product of a diamine and a poly(p-phenylene terephthalamide).

44. The assembly of claim 4 wherein the condensation polymer comprises a polybenzimidazole.

45. The assembly of claim 4 wherein the condensation polymer comprises a polyarylate.

46. The assembly of claim 45 wherein the polyarylate polymer comprises a condensation polymerization reaction product between bis-phenol-A and mixed phthalic acids.

47. The assembly of claim 1 wherein the flexible bag substrate comprises a filter tube having an open end and a closed end, said open end having a seal, the gaseous stream exiting from at least a portion of the interior of the bag section.

48. The assembly of claim 47 wherein the filter tube comprises a woven fabric.

49. The assembly of claim 47 wherein the filter tube comprises a non-woven fabric.

50. The assembly of claim 47 wherein the filter tube section comprises a polyester fiber.

51. The assembly of claim 47 wherein the filter tube comprises a cotton fiber.

52. The assembly of claim 47 wherein the filter can pass about 5 to about 15 cubic feet per minute of gaseous media per square foot of filter media.

53. The assembly of claim 47 wherein there are about 10 to about 100 filter tubes in the housing.

54. The assembly of claim 47 wherein the filter tube comprises a layer of fine fiber on an upstream surface of the filter tube and a second layer of fine fiber on an exit surface of the filter tube.

76. The assembly of claim 47 wherein the fine fiber is covered with a layer that prevents abrasion of the fine fiber layer.

77. The assembly of claim 76 wherein the layer that prevents abrasion comprises a scrim with a basis weight of about 0.2 to 2 oz-yd⁻

2.

78. The assembly of claim 47 wherein the filter tube comprises a layer of fine fiber on the exit surface of the filter tube.

79. The assembly of claim 4 wherein the condensation polymer comprises a nylon polymer, and a resinous additive comprising an oligomer having a molecular weight of about 500 to 3000 and an aromatic character wherein the additive is miscible in the condensation polymer.

80. The assembly of claim 47 wherein the layer of fine fiber has a thickness of about 0.1 to about 3 microns and has a basis weight of about 0.001 to 0.1 milligram per square centimeter.

55. A bag house filter apparatus comprising:

(a) a housing defining an interior, an inlet and an outlet;

(b) a frame mounted within the housing interior;

(c) at least two filter bags each bag configured for treating industrial effluent or off-gas each bag mounted on and sealed against said frame;

(i) each of said filter bags having an exterior, upstream surface and an interior, downstream surface defining an interior volume;

each of the filter bags having a clean air opening communicating with the interior volume; and

(ii) each filter bag exterior surface having uniformly deposited thereon a fine fiber layer with a thickness of 0.1 to 3 microns, a diameter of 0.001 to 0.5 microns and a basis weight of about 0.0005 to 0.2 mg-cm<sup>−

2</sup>; and

(d) a blower arrangement to move an air stream through the housing inlet, through the filter bags from the upstream surface to the downstream surface into the interior volume and then exit the interior volume through the clean air opening, and through the housing outlet.

56. An apparatus according to claim 55 wherein each of the filter bags is rectangular, with substantially parallel walls.

57. An apparatus according to claim 55 wherein each of the filter bags is tube-shaped.

58. An apparatus according to claim 55 wherein each of the filter bags comprises a woven fabric.

59. An apparatus according to claim 55 wherein each of the fabric bags comprises a non-woven fabric.

60. An apparatus according to claim 55 wherein each of the filter bags comprises a polyester fiber.

61. An apparatus according to claim 55 wherein each of the filter bags comprises a cotton fiber.

62. An apparatus according to claim 55 wherein the filter apparatus can pass about 5 to about 15 cubic feet per minute of gaseous media per square foot of filter media.

63. An apparatus according to claim 55 wherein there are about 10 to about 100 filter bags in the housing.

64. An apparatus according to claim 55 wherein each of the filter bags comprises a layer of fine fiber on the upstream surface of each of the filter bags and a second layer of fine fiber on the exit surface of each of the filter bags.

65. An apparatus according to claim 55 wherein the layer of fine fiber has a basis weight of about 0.001 to 0.1 milligram per square centimeter.

66. A method of filtering an air stream containing a particulate, the method comprising the steps of:

(a) placing an air filtration bag within a filter housing having an air inlet and an air outlet, said filter housing comprising a frame support within the housing dividing the housing into two sections, a clean section and a dirty section, the housing and frame comprising a series of flexible filter bags of an air pervious material, each bag configured for industrial effluent of off-gas, each bag including a substantially open upper end and a seal to the frame, sealing members secured to at least one of the filter bags maintaining the separation between the clean section and the dirty section, air pervious support means within said bags to prevent the bags from collapsing and means in one section of the housing to cause air to pass through the bags;

(b) and passing the air through the filter bags to ensure that the particulate is removed from the air stream, said filter bag having an exterior surface and an interior surface, the exterior surface having uniformly deposited thereon a fine fiber layer at a basis weight of about 0.0005 to 0.2 mg-cm<sup>−

2</sup> and a thickness of 0.1 to 3 microns, the fiber having a diameter of 0.01 to 5 microns, said air passing into the bag and exiting the interior surface.

67. The method of claim 66 wherein the filtration method includes a pulse cleaning step wherein dust forming on the exterior of the bag is removed by a short reversal of the air flow resulting in a substantially reduced pressure drop.

68. The method of claim 66 wherein the filtration method includes a mechanical vibratory cleaning of the bag wherein dust forming on the exterior of the bag is removed by a vibration resulting in a substantially reduced pressure drop.

69. A method of making a filter bag for an industrial bag house, the steps comprising:

(a) forming a layer of fine fiber on an industrial bag house fabric, the fiber having a diameter of about 0.01 to 0.5 microns and a basis weight of about 0.0005 to 0.2 mg-cm<sup>−

2</sup>, said layer having a thickness of about 1 to 100 times the fiber diameter forming a fiber and fabric; and

(c) assembling the fiber and fabric into a bag configured for industrial effluent or off-gas filtration.

70. The method of claim 69 wherein a step of heat treating the fiber and fabric for a period of time that effectively increases the adhesion of the fiber to the fabric forming an adhered fiber and fabric.

71. The method of claim 70 wherein the heat treating step is performed after the bag is assembled.

72. The method of claim 69 wherein the fiber and fabric is made into the form of a roll of fiber and fabric and the fiber and fabric is unrolled, cut and sewn into the bag.

73. The method of claim 69 wherein the fiber is electrospun onto a woven fabric.

74. The method of claim 70 wherein the fiber and fabric are heat treated at a temperature less than a melting point of one of the fine fibers.

75. The method of claim 69 wherein the layer of fine fiber is formed on the fabric by laminating a preformed fine fiber layer.

81. A filter bag for an industrial bag house, the bag comprising:

(a) a layer of fine fiber, on an upstream surface of the bag, the bag comprising a layer of an industrial bag house fabric, the fine fiber layer having a fiber diameter of about 0.01 to 0.5 microns and a basis weight of about 0.0005 to 0.2 mg-cm<sup>−

2</sup>, said fine fiber layer having a thickness of about 1 to 100 times thickness of the fine fiber;

wherein after test exposure for a test period of 16 hours to test conditions of 140°

F. air and a relative humidity of 100% the bag retains greater than 30% of the fine fiber unchanged for filtration purposes and the bag is sized to pass 5 to 15 cubic fact per minute of gaseous media per square feet of filter media.

82. The bag of claim 81 wherein the line fiber is covered with a layer that prevents abrasion of the fine fiber layer, and the bag comprises a tube with an open end and a closed end.

83. The bag of claim 81 wherein the polymer comprises an addition polymer and an additive that forms a coating on the fiber.

84. The bag of claim 83 wherein the polymer comprises a nylon and the additive forms a coating on the fiber with hydrophobic properties.