Electrostatic spray nozzles for abrasive and conductive liquids in harsh environments

• US 5,704,554 A
• Filed: 03/21/1996
• Issued: 01/06/1998
• Est. Priority Date: 03/21/1996
• Status: Expired due to Term

• Current Assignee: The University of Georgia Research Foundation, Inc.
• Original Assignee: The University of Georgia Research Foundation, Inc.
• Inventors: Cooper, Steven C., Law, S. Edward
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Douglas, Lisa Ann
• Application Number:
  US08/620,088
• Time in Patent Office: 656 Days
• Field of Search: 239/690, 239/690.1, 239/692, 239/695, 239/697, 239/704-8, 239/105, 361/227, 361/228
• US Class Current: 239/690.1
• CPC Class Codes: B05B 5/03 characterised by the use of gas , e.g. electrostatically assisted pneumatic spraying B05B5/04, B05B5/043, B05B5/047 take precedence
• CPC Class Codes: B05B 5/043 using induction-charging
• CPC Class Codes: B05B 5/0533 Electrodes specially adapted therefor; Arrangements of electrodes
• CPC Class Codes: B05B 5/1608 the liquid or other fluent material being electrically conductive

Abstract

Air atomizing induction charging spray nozzles suited for use with conductive liquids, solutions, suspensions or emulsions. These systems feature a high level of the spray charging at low induction--electrode voltage and current. Primary benefits include consistent, reliable operation in harsh agricultural and industrial environments with a wide range of spray formulations, especially those having relatively high concentrations of abrasive and conductive materials. Internal and external surfaces are configured to minimize potential differences between electrode and ground. Such nozzles may employ external cavities, field concentrators, hoods and other structures and arrangements to affect aerodynamic flow of gases within the vicinity of the nozzles and electrostatic and electrodynamics effects such as those caused by electrical fields within the vicinity of the nozzles.

Claims

1. An induction spray-charging nozzle comprising:

a. a body including a liquid channel and a gas channel, the liquid channel terminating in a tip;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid emanating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle;

(ii) an electrode at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel;

(iii) an outer surface which is shaped to reduce turbulence of air flowing adjacent to the cover; and

c. at least one annular shaped cavity formed on an outside surface of the nozzle, the cavity adapted in shape to reduce reception of liquid and gas and other surface contaminants, and to reduce current flowing between the electrode and electrical ground.

2. A nozzle according to claim 1 in which the electrode is formed of abrasion resistant material.

3. A nozzle according to claim 1 further comprising an abrasion resistant outlet forming a portion of the channel.

4. A nozzle according to claim 3 in which the body tip contains structure adapted to modify flow of the gas emanating from body into an at least partially helical pattern.

5. A nozzle according to claim 3 in which the outlet is formed of ceramic material.

6. A nozzle according to claim 1 further comprising a flange disposed between an outer surface of the body and an outer surface of the cover, adapted to reduce the liquid, gas and other surface contaminants received in the annular cavity.

7. A nozzle according to claim 1 further comprising a flange disposed between an outer surface of the body and an outer surface of the cover, adapted to reduce current flow between the electrode and ground.

8. A nozzle according to claim 1 in which the body comprises the annular cavity.

9. A nozzle according to claim 1 in which the cover comprises the annular cavity.

10. A nozzle according to claim 1 in which the body and the cover each comprise one of the annular cavities.

11. A nozzle according to claim 1 in which the outer surface of the cover is substantially forwardly tapered toward an outlet of the channel.

12. A nozzle according to claim 1 in which the cover contains a conductive surface which renders predetermined locations on inner surfaces of the cover to be at substantially equal potential.

13. A nozzle according to claim 1 further comprising a hood connected to the nozzle, the hood adapted in shape to shield at least part of outside surfaces of the nozzle from liquid, gas and other surface contaminants.

14. A nozzle according to claim 1 further comprising a hood connected to the nozzle, the hood adapted in shape to shield at least part of said annular cavity from liquid, gas and other surface contaminants.

15. A nozzle according to claim 1 in which the electrode is coupled to a power supply via a resistive element that features a resistance of at least one thousand ohms.

16. A nozzle according to claim 15 in which the resistive element is contained in the cover.

17. A nozzle according to claim 15 in which the resistive element is contained in the body.

18. A nozzle according to claim 15 in which the resistive element is contained in a conductor that couples the nozzle to the power supply.

19. A nozzle according to claim 15 comprising a plurality of resistive elements whose total resistance exceeds one thousand ohms.

20. A nozzle according to claim 1 in which the body further comprises a conductive element adapted to assist in applying voltage to the electrode.

21. A nozzle according to claim 1 in which the cover further comprises a conductive element adapted to assist in applying voltage to the electrode.

22. A nozzle according to claim 21 in which the conductive element in the cover is formed at least partially of a thermoplastic material which features a resistance of at least one thousand ohms.

23. A nozzle according to claim 21 in which the conductive element in the cover features a resistance of at least one thousand ohms.

24. A nozzle, comprising:

a. a body including a liquid channel and a gas channel, the liquid channel terminating in a tip;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid emanating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle;

(ii) an electrode at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel;

(iii) an outer surface which is shaped to reduce turbulence of air flowing adjacent to the cover;

c. a conductive element adapted to couple the electrode to a power supply;

d. a conductive surface connected to the cover, coupled to the conductive element and adapted to cause the potential at predetermined locations on inner surfaces of the cover to be substantially at the same potential; and

e. at least one annular shaped cavity formed on an outside surface of the nozzle, the cavity adapted in shape to reduce reception of liquid, gas and other surface contaminants, and to reduce current flowing between the electrode and electrical ground.

25. A nozzle according to claim 24 in which each of the body and the cover comprises an annular shaped cavity.

26. A nozzle according to claim 24 in which only one of body and the cover comprises an annular shaped cavity.

27. A nozzle according to claim 24 in which the electrode is formed of an abrasion resistant material.

28. A nozzle according to claim 24 further comprising an abrasion resistant outlet forming a portion of the channel.

29. A nozzle according to claim 28 in which the outlet is formed of ceramic material.

30. A nozzle according to claim 24 in which the conductive element features a resistance of at least one thousand ohms.

31. A nozzle according to claim 24 in which outside surface of the cover is substantially forwardly tapered toward an outlet of the channel.

32. A nozzle according to claim 24 further comprising a flange interposed between the body and the cover, the flange adapted in shape at least partially to shield said annular shaped cavity from liquid, gas and other surface contaminants.

33. A nozzle according to claim 24 further comprising a flange interposed between the body and the cover, the flange adapted in shape to reduce current between the electrode and electrical ground.

34. A nozzle according to claim 24 further comprising a hood attached to the nozzle, the hood adapted in shape at least partially to shield said annular shaped flange from liquid, gas and other surface contaminants.

35. A nozzle, comprising:

a. a body including a liquid channel and a gas channel, the liquid channel terminating in a tip;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid emanating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle;

(ii) an electrode formed of abrasion resistant material positioned adjacent to and at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel; and

(iiii) a conductive element adapted to couple the electrode to a power supply; and

c. an outside surface formed on the nozzle adapted in shape to reduce current flowing between the electrode and electrical ground, said outside surface substantially forwardly tapered toward an outlet of the channel.

36. A nozzle according to claim 35 further in which the cover comprises an electrical surface coupled to the conductive element which is adapted to maintain locations on inner surfaces of the cover at substantially equal potential.

37. A nozzle according to claim 35 in which the conductive element features a resistance of at least one thousand ohms.

38. A nozzle according to claim 35 further comprising a hood attached to the nozzle adapted in shape to shield at least part of the nozzle from liquid, gas and other surface contaminants.

39. A nozzle according to claim 35 in which the outside surface formed on the nozzle adapted in shape to reduce current flowing between the electrode and electrical ground comprises a flange extending from the nozzle adapted in shape to reduce current flowing from the electrode to ground.

40. A nozzle according to claim 35 in which the outside surface formed on the nozzle adapted in shape to reduce current flowing between the electrode and electrical ground comprises a hood extending from the nozzle adapted in shape to reduce current flowing from the electrode to ground.

41. A nozzle, comprising:

a. a body including a liquid channel and a gas channel, the liquid channel terminating in a tip;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid eminating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle;

(ii) an electrode formed of abrasion resistant material positioned adjacent to and at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel; and

(iii) a conductive element adapted to couple the electrode to a power supply; and

c. an outside surface formed on the nozzle adapted in shape to reduce current flowing between the electrode and electrical ground, said outside surface comprising an annular cavity.

42. A nozzle according to claim 41 further comprising another annular cavity formed on an outer surface of the body, the cavities adapted in shape to receive reduced amounts of liquid, gas and other surface contaminants.

43. A nozzle according to claim 41 in which said annular cavity is adapted in shape to receive reduced amounts of liquid, gas and other surface contaminants.

44. A nozzle according to claim 41 in which the annular shaped cavity is adapted in shape to reduce current flowing from the electrode to ground.

45. A nozzle according to claim 44 in which the annular shaped cavity is formed on the outer surface of the cover.

46. A nozzle according to claim 44 in which the annular shaped cavity is formed on the outer surface of the body.

47. A nozzle according to claim 44 in which an annular shaped cavity is formed on the outside surface of each of the cover and the body.

48. A nozzle, comprising:

a. a body that includes a liquid channel for transmission of liquid and a gas channel for transmission of gas, the liquid channel terminating in a tip, the tip and the body connected with no seams through which electrical current flows to the liquid;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid emanating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle; and

(ii) an electrode formed of abrasion resistant material positioned at least partially surrounding the channel, adapted to cream electrical charge in the liquid flowing in the channel;

c. the liquid grounded upstream from the tip;

d. at least one surface formed on the nozzle to increase impedance of the surface to currents flowing between the electrode and ground, said surface; and

e. an outside surface formed on the nozzle, said outside surface comprising at least one annular shaped cavity formed on the surface of the nozzle and adapted in shape to reduce current flowing from the electrode to ground.

49. A nozzle according to claim 48 further comprising a port communicating with said gas channel and adapted to introduce gas into said at least one cavity in order to purge said at least one cavity.

50. An induction spray-charging nozzle comprising:

a. a body including a liquid channel and a gas channel;

b. a cover connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid and gas emanating from the body flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle;

(ii) an electrode at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel; and

(iii) an outer surface which contains;

a. at least one cavity adapted in shape to reduce current flowing from the electrode to ground; and

b. at least one field concentrator adapted in shape to concentrate the intensity of electrical fields in the vicinity of the field concentrator.

51. A nozzle according to claim 50 in which the field concentrator is located in the vicinity of the cavity in order to deflect foreign matter from entering the cavity.

52. A nozzle according to claim 50 in which the field concentrators are edges formed on the surface of the nozzle.

53. A nozzle according to claim 50 in which the cavities are annular cavities formed in the surface of the nozzle.

54. A nozzle according to claim 50 in which the field concentrators are adapted in shape to cause formation of curved electrical field lines in the vicinity of the field concentrators.

55. A nozzle, comprising:

a. a body that includes a liquid channel for transmission of liquid and a gas channel for transmission of gas, the liquid channel terminating in a tip, the tip and the body connected with no seams through which electrical current flows to the liquid;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid emanating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle; and

(ii) an electrode formed of abrasion resistant material positioned at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel;

c. the liquid grounded upstream from the tip; and

d. at least one surface formed on the nozzle to increase impedance of the surface to currents flowing between the electrode and ground; and

e. an outer surface formed on said nozzle, said outer surface substantially forwardly tapered toward an outlet of the channel.

56. A nozzle according to claim 55 in which the surface formed on the nozzle comprises a flange extending from the nozzle adapted in shape to reduce current flowing from the electrode to ground.

57. A nozzle according to claim 55 in which the outside surface formed on the nozzle comprises a hood extending from the nozzle adapted in shape to reduce current flowing from the electrode to ground.

58. A nozzle according to claim 55 in which the outside surface formed on the nozzle comprises at least one annular shaped cavity formed on the surface of the nozzle and adapted in shape to reduce current flowing from the electrode to ground.

59. A nozzle according to claim 58 in which the annular shaped cavity is formed on the outer surface of the cover.

60. A nozzle according to claim 58 in which the annular shaped cavity is formed on the outer surface of the body.

61. A nozzle according to claim 58 in which at least one annular shaped cavity is formed on the outside surface of each of the body and the cover.

62. A nozzle according to claim 58 further comprising a port communicating with the gas channel and adapted to introduce gas into the cavities in order to purge the cavities.

63. A nozzle according to claim 55 in which an outer surface of the cover is adapted in shape to reduce turbulence of airflow in the vicinity of the cover.

64. A nozzle according to claim 55 in which the void into which liquid emanating from the tip and gas emanating from the body flows is non-convergent.

65. A nozzle according to claim 55 in which the nozzle further comprises a conductive element adapted to assist in applying voltage to the electrode, and in which the nozzle is adapted to interrupt electrical contact between the conductive element and the electrode when the cover is removed.

66. A nozzle according to claim 55 in which the cover includes an outside surface adapted in shape to act as an electric field barrier when coated with surface contaminants.

67. A spray-charging nozzle, comprising:

a. a nozzle body including a liquid channel for transmission of liquid, a gas channel, the nozzle body containing no seams through which electrical current flows to the liquid;

b. a cover disposed on said body in fluid-tight manner, said cover including an outlet port through which atomized liquid and gas emanate through an outlet face of the cover into the air surrounding the nozzle in a desired spray pattern, said cover forming no portion of said liquid channel;

c. an electrode disposed within said outlet port, upstream of said outlet face of said cover, downstream of said fluid channel and coupled to a power supply through no conduits which communicate with said liquid channel, said electrode adapted to impart a charge to the liquid that emanates into the air, charge from said electrode unable to migrate on surfaces of said nozzle between said electrode and a liquid line for providing liquid to said liquid channel without migrating across external surfaces of said nozzle;

d. a liquid line, a gas line, and an electrical line for providing liquid, gas and voltage to the liquid channel, gas channel and electrode, respectively;

e. the liquid grounded upstream of the outlet port; and

f. the nozzle including an outside surface adapted in shape to increase impedance to current flowing from the electrode to ground.

68. A nozzle according to claim 67 in which the nozzle outside surface comprises a flange extending from the nozzle adapted in shape to reduce current flowing from the electrode to ground.

69. A nozzle according to claim 67 in which the nozzle outside surface comprises a hood extending from the nozzle adapted in shape to reduce current flowing from the electrode to ground.

70. A nozzle according to claim 69 in which the hood is adapted to reduce turbulence in air flowing in the vicinity of the nozzle.

71. A nozzle according to claim 67 in which the nozzle outside surface comprises at least one annular shaped cavity formed on the surface of the nozzle and adapted in shape to reduce current flowing from the electrode to ground.

72. A nozzle according to claim 71 in which the annular shaped cavity is formed on the outer surface of the cover.

73. A nozzle according to claim 71 in which at least one annular shaped cavity is formed on the outside surface of each of the body and the cover.

74. A nozzle according to claim 71 in which the annular shaped cavity is formed on the outer surface of the body.

75. A nozzle according to claim 67 further comprising a hood connected to at least one of the liquid line, gas line and electrical line for protecting surfaces of the nozzle against undesired deposition of liquid, gas and other surface contaminants.

76. A nozzle according to claim 75 in which the hood is adapted in shape to reduce current flowing from the electrode to ground.

77. An induction spray-charging nozzle comprising:

a. a body including a liquid channel terminating in a tip and a cover removably connected to the body;

b. the cover including an electrode and forming a channel through which liquid and gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from an outlet of the channel into the air surrounding the nozzle;

c. at least one outer surface that is;

(i) adapted in shape to reduce contaminant deposit on the nozzle by including a tapered surface that is tapered toward the outlet to (A) present a smaller surface area in the vicinity of the outlet than at other locations on the nozzle; and

(B) present an aerodynamic surface that substantially decreases turbulent airflow in the vicinity of the nozzle; and

(ii) adapted in shape to reduce electrical current flowing between the electrode and ground, by including surface features that are adapted in shape to increase the impedance presented by the outer surface to current flowing from the electrode to ground; and

d. an electrode power supply which is coupled to the nozzle structure.

78. A nozzle according to claim 77 in which the wall of the channel is at least partially made of abrasion resistant material.

79. A nozzle according to claim 78 in which the wall of the channel is at least partially made of ceramic material.

80. A nozzle according to claim 77 in which said power supply is mounted to the body portion of the nozzle.

81. A nozzle according to claim 77 in which said power supply is mounted within the body portion of the nozzle.

82. A nozzle according to claim 77 in which said power supply is mounted to the cover portion of the nozzle.

83. A nozzle according to claim 77 in which said power supply is mounted within the cover portion of the nozzle.

84. A nozzle according to claim 77 in which said power supply has input leads which emanate from a low voltage body portion of the nozzle.

85. A nozzle according to claim 77 in which said power supply has input leads which have shields formed on them to reduce contaminant deposit.

86. A nozzle, comprising:

a. a body including a liquid channel and a gas channel, the liquid channel terminating in a tip;

b. a cover removably connected to the body, said cover comprising at least partially insulative material, the cover including;

(i) an inner surface which cooperates with an outer surface of the body to form at least one void into which liquid emanating from the tip and gas emanating from the body may flow, the cover forming a channel through which the liquid and the gas flow, the channel adapted in shape to cause atomized liquid and gas to emanate properly from the channel into air surrounding the nozzle;

(ii) an electrode formed of abrasion resistant material positioned adjacent to and at least partially surrounding the channel, adapted to create electrical charge in the liquid flowing in the channel; and

(iii) a conductive element adapted to couple the electrode to a power supply; and

c. an outside surface formed on the nozzle adapted in shape to reduce current flowing between the electrode and electrical ground, said outside surface adapted in shape to reduce turbulence of air flowing around the nozzle and electrically to deflect matter emanating from the nozzle from entering cavities formed on outside surfaces of the nozzle.