FR2764215A1 - LANCE AND APPARATUS FOR PRODUCING A LIQUID C02 JET, AND ITS APPLICATION TO A SURFACE CLEANING INSTALLATION - Google Patents

Abstract

The invention relates to a lance for producing a jet of liquid CO2, comprising means (5) for connection to a source of liquid CO2 under pressure, means (3, 91) for expanding the liquid CO2 under pressure and means (9) ejection of the expanded liquid CO2 in a jet. The liquid CO2 expansion means comprise means (3) of progressive expansion. Application to the cleaning of surfaces in the electronics industry.

Description

The invention relates to a lance for producing a liquid CO2 jet,

  comprising means for connection to a source of liquid CO2 under pressure, means for expanding the liquid CO2 under pressure and means for ejecting the expanded liquid CO2 in a jet. Many fields of activity, such as the electronic industry or the medical field, call for micro-cleaning or pollution control of surfaces. The solvents traditionally used for these cleaning operations, such as trichlorethylene or Freon (registered trademark), cause non-recyclable fumes and the

  legislation tends to prohibit their use.

  CO2 is a substitute solvent, which, applied in the form of a jet of liquid, proves to be competitive and effective for cleaning operations

or surface remediation.

  However, the production of jets of liquid CO2 of cross section and flow rate compatible with the envisaged applications, from the usual storage pressures of liquid CO2 (P = 55 bars at 20 C

  and P = 20 bars at -20 C), poses many problems.

  In particular, the existence of a triple point in its field of use, unlike the Freon, poses the problem of the appearance, during the expansion of liquid CO2, of carbon dioxide snow which can block the

  means for relaxing or ejecting the lance.

  The object of the invention is to remedy the problems mentioned above and, in particular, to provide a lance for producing a jet of liquid which can be used in cleaning applications.

  and adapted to the physical characteristics of C02.

  To this end, the subject of the invention is a lance for producing a jet of liquid C02, comprising means for connection to a source of liquid C02 under pressure, means for expanding the liquid CO2 under pressure and means for ejection of the expanded liquid CO2 in a jet, characterized in that the means for expanding the liquid CO2 include means for

progressive relaxation.

  According to particular embodiments, the lance comprises one or more of the following characteristics: - the means of progressive expansion comprise a capillary tube, in particular wound in a helix; the ejection means comprise a nozzle for ejecting the expanded liquid CO2 provided with means for adjusting the opening of the jet of liquid CO2 produced; - Said adjusting means comprise means for injecting an air flow into the jet of liquid CO2 produced, and means for adjusting the flow rate of the injected air flow; - Said adjusting means comprise a channeling member adapted to surround an upstream part of the jet of liquid CO2 produced and thus create an air suction between the jet of liquid CO2 and the channeling member; said adjustment means comprise a tube surrounding the ejection nozzle at a distance and provided with an air inlet opening, and a pipe nozzle surrounding the ejection nozzle at a distance, the pipe nozzle being operable and movable between a retracted position, in which it closes the air inlet opening of the tube, and an active position in which it at least partially releases the air inlet opening of the tube and in which a part before the pipe nozzle is adapted to surround part of the jet of liquid C 2 produced; - In its active position, said front part of the pipe nozzle forms a blaster for producing carbon dioxide snow;

  - the ejection means are interchan-

  geables; - The lance constitutes a manual lance comprising a body forming a handle for orienting the jet of liquid CO2 produced, and it comprises means forming a valve for adjusting the flow rate of the jet of liquid CO2 produced, controlled by a control member which can be operated by the hand of an operator who holds the handle body; the progressive expansion means comprise a capillary tube, and the valve means comprise a movable member connected to one end of the capillary tube, and the capillary tube is wound in a helix to adapt to the movement of said movable member; and - the valve means comprise a shut-off valve, located downstream of said progressive expansion means, and the control member comprises a trigger connected to a trigger

  actuation of the shutter of the stop valve.

  The invention also relates to an apparatus for producing a liquid CO2 jet, characterized in that it comprises on the one hand at least one lance as defined above, associated with at least one solenoid valve for adjusting the flow rate of the liquid CO2 jet produced by the lance, and a unit for controlling the opening of the or each solenoid valve. The invention also relates to a surface cleaning installation by liquid CO2 jet, characterized in that it comprises an apparatus as defined above and means for relative displacement of a surface to be cleaned by

report to the spear.

  The invention may also include means for evacuating the gaseous CO2 produced during

ejection of liquid CO2.

  The invention ultimately relates to

  ejection means for a lance as defined above

  above. The ejection means may comprise a nozzle for ejecting expanded liquid CO 2, a body for connection to the means of progressive expansion of a lance, a ring for mounting on the lance, a tube surrounding the ejection nozzle at a distance and provided with an air inlet opening, and a pipe nozzle surrounding the ejection nozzle at a distance, the pipe nozzle being manoeuvrable and movable between a retracted position, in which it closes the inlet opening d air from the tube, and an active position in which it at least partially frees the air inlet opening of the tube and in which a front part of the pipe nozzle is adapted

  to surround part of the jet of liquid CO2 produced.

  The invention will be better understood on reading

  of the description which follows, given only to

  by way of example, and made with reference to the accompanying drawings in which: - Figure 1 is a longitudinal section view of a lance according to the invention, - Figure 2 is an enlarged view of the ringed part II of FIG. 1, the trigger being pressed, - FIG. 3 is a view on a larger scale of the circled part III of FIG. 1, the nozzle for channeling an air flow being in the active position for channeling d 'an air flow, and - Figure 4 is a schematic view of a surface cleaning installation according to the invention. FIG. 1 illustrates a lance for producing a jet of liquid CO2 comprising a hollow body 1 of generally cylindrical shape in which are housed means 3 for progressive expansion of liquid CO2 under pressure. These means 3 are connected on the one hand, upstream, to means 5 for connection to a source 4 of pressurized liquid CO2, situated at an upstream end 7 of the body 1, and on the other hand, downstream, to means 9 for ejecting a relaxed liquid CO2 in a jet, situated at the downstream end 11 of the body 1. Means 13

  forming valve for regulating the flow of the jet of CO-

  liquid produced are arranged in the body 1 between the means 3 for progressive expansion of the liquid CO2 and the

  means 9 for ejecting liquid CO2.

  The body 1 is crossed by a bore

  longitudinal 15 threaded at the end 7.

  The connection means 5 consist of a conventional male connector 17, screwed into the end 7 of the body 1, making it possible to connect the lance, via a hose 18, to the source 4 of C02

liquid under pressure.

  This connector 17 is traversed by a stepped longitudinal bore, coaxial with the bore 15, comprising, successively from upstream to downstream, an inlet portion 19 of large diameter, a converging portion 21, a portion 23 of small section , then a portion 25 of section slightly larger than the section of the portion 23 and opening into the bore 15. A shoulder

  transverse 27 connects parts 23 and 25.

  The means 3 for progressive expansion comprise a capillary tube 29, wound in a helix, housed in the body 1, the helix formed being substantially coaxial with the bore 15. The tube 29 is of

substantially constant section.

  The two ends 31 and 33 of the tube 29 are rectilinear and coaxial with the bore 15. The upstream end 31 of the tube 29 is housed in the part 25 of the bore of the connector 17, its edge resting on the shoulder 27 A solder 35 is produced between the fitting 17 and the emerging part of the end 31 of the

tube 29.

  The inner section of the tube 29 and the section of the part 23 of the bore of the fitting 17 are

substantially equal.

  The means 13 forming a valve for adjusting the flow rate of the jet of liquid CO2 produced comprise a member 37 of generally cylindrical shape, slidably mounted in the bore 15 of the body 1, and connected by its upstream end 39 to the downstream end 33 of the tube 29. The member 37 is traversed by a stepped longitudinal bore 41 coaxial with the bore 15. This bore 41 comprises, from the end 39, parts

  successive 43, 45, 47 and 49 of decreasing sections.

  Part 43 is tapped and receives by screwing a connector 51 of generally cylindrical stepped shape,

  crossed by a stepped longitudinal bore 53.

  The bore 53 successively has a first part 55 for receiving the downstream end 33 of the tube 29, and a second part 57 of section substantially equal to the internal section of the tube 29 and opening out

in part 47 of bore 41.

  An O-ring 59, arranged in a circular groove provided at the downstream end (on the right in FIG. 1) of the connector 51 provides sealing between the downstream part of the connector 51 and the part 45 of the bore 41 in which it is received. A solder 60 is produced, in the same way as the solder 35, between the downstream end 33 of the tube and the fitting 51. The downstream end edge of the tube 29 is supported on a shoulder joining the parts 55 and 57 of the bore 53. A ball 61 for closing the passage between parts 47 and 49 of bore 41 is disposed with a radial clearance in part 47 of bore 41. Its seat is constituted by a converging surface 63 connecting the parts 47 and 49 of bore 41, and the ball 61 is held against its seat 63 by a

  helical spring 65 bearing on the fitting 61.

  The means 13 forming a valve also comprise a part 67 for maneuvering the ball, of generally stepped cylindrical shape, pierced with a longitudinal bore 69 coaxial with the bore 15. This part 67 is terminated upstream by a tapered part 71 the end of which is pierced with transverse openings or notches 72. This part 71 is slidably received in the part 49 of the bore 41. An O-ring 73, surrounding the tapered part 71, is housed in a groove inner circular part 49 of the bore 41, thus ensuring the seal between the parts 49 and 71. The downstream end 74 of the part 67 forms a support flange of a helical spring 75 threaded on the part 67 and also resting on the member 37. The member 37 comprises, on its outer surface, an annular groove 77, opposite which a lever 79 is rotatably mounted on the body 1 of the lance thanks to a pin 80 s' extending between two flanges 81 lo ngitudinal projecting from the body 1. A first arm 83 of the lever 79 forms a trigger and the other arm 85 forms a trigger, the free end of the arm 85 advancing through an opening 84 formed

in body 1, in throat 77.

  The means 9 for ejecting the expanded liquid CO2 comprise a connecting body 87, of generally cylindrical stepped shape, crossed by a stepped bore 89 coaxial with the bore 15, and receiving an ejection nozzle 91 in the form of a tube capillary coaxial with the bore 15. The upstream end of this tube abuts against an intermediate shoulder of the bore 89. A solder 92 is produced between the nozzle 91 and the body 87. The body 87 comprises three successive cylindrical parts 93, 95 and 97 of decreasing section while moving towards the front of the lance (on the right in FIG. 1), the part 93 being received in a sliding manner in the bore 15 and an O-ring 96 ensuring the sealing between the walls in

  look at bore 15 and part 93.

  A ring 101 resting on a transverse shoulder joining the parts 93 and 95 of the body 87 is screwed onto the end 11 of the body 1, which is threaded. The part 67 is held against the body 87 by the spring 75, the bores 69 and 89 of the part 67 and of the body 87 communicating in leaktight manner and being

substantially the same section.

  A vent 102 is drilled in the body 1 between the front end (on the right in FIG. 1) of

  organ 37 and part 93 of body 87.

  From a transverse shoulder joining the parts 95 and 97 of the body 87 leaves, towards the front end of the lance, a tube 103 guided on the part 97 of the body 87, this tube 103 being coaxial with the nozzle 91 and surrounding at a distance part of this nozzle 91. The

  front part 105 of this nozzle protrudes from the tube 103.

  Two transverse orifices 107 pass through the wall of the tube 103, allowing the circulation of air

  between the outside and the inside of the tube 103.

  A pipe nozzle 109, of general shape of revolution, convergent and coaxial with the nozzle 91, is slidably mounted on the front end of the tube 103. This nozzle 109 has a cylindrical rear part 111 surrounding the front end of the tube 103, and a cylindrical front part 113 surrounding at

  a short distance from the front end of the nozzle 91.

  Parts 111 and 113 are connected by a part

convergent 114.

  A pin 115 secured to the front part of the tube 103 is received in an oblong longitudinal opening 116 of the part 111 of the nozzle 109. The pin limits the translation of the nozzle 109 on the tube 103 between two positions: on the one hand , a retracted position (FIG. 1), in which the rear part of the nozzle 111 closes the orifices 107, and in which the front part 105 of the nozzle 91 projects from the front part 113 of the nozzle 109; and on the other hand, an active position for channeling an air flow (FIG. 3), in which the nozzle 109 completely releases the orifices 107 and in which the front part 111 of the nozzle 109 projects forward ( right in Figure 1) relative to the front end 105 of

nozzle 91.

  The lance being connected via the connector 17 and the hose 18 to the source 4 of CO, liquid under pressure, the means 13 forming a valve are in the rest position shown in FIG. 1, the ball 61 closing the passage between parts 47 and

  49 of bore 41 of member 37. The source of CO.

  pressurized liquid is therefore placed in communication with the bore of the connector 17, the capillary tube 29, the part 57 of the bore 53 of the connector 51 and the part 47

of bore 41.

  When an operator wishes to use the lance to produce a jet of liquid CO2, the latter grasps with one hand the body 1 forming a handle as well as the arm 83 of the lever forming the trigger and, by tightening the grip, brings the arm 83 closer to the body 1 by rotating the lever 79 counterclockwise in FIG. 1. The arm 85 then pushes the member 37 forward (on the right in FIG. 1) in the body 1 by compressing the spring 75. The tapered part 71 of the part 67 slides in the part 49 of the bore 41 of the member 37 and pushes the ball 61, moving it away from its seat 63 (FIG. 2). The ball 61, under the action of

  this displacement compresses the spring 65.

  The ball 61 having left its seat and the end of the part 71 being pierced with openings 72, the source of pressurized liquid CO2 is put, by means of the bore 69 of the part 67, of the bore 89 of the body 87 and of the capillary tube 91, in

  communication with the ambient atmosphere.

  The liquid CO2 then flows from the source to the ambient atmosphere. It undergoes progressive expansion in the capillary tube 29 which, by its dimensional characteristics (length and section) makes it possible to induce a significant pressure drop while slowing the flow of the liquid CO 2 and therefore limiting the flow of the relaxed liquid CO 2. The flow of liquid CO2 is indicated by arrows in line

bold in Figures 2 and 3.

  The expanded liquid CO2 is then conveyed to the outlet of the capillary tube 91, where it expands to ambient pressure producing a fine jet and of limited flow rate, suitable for cleaning operations. By moving the nozzle 109 by hand, from its retracted position (FIG. 1) to its active position (FIG. 3), the operator can progressively place the front part 113 of this nozzle around the jet of liquid CO2 produced while the rear part 111

  of the nozzle 109 gradually releases the orifices 107.

  The jet of liquid CO2 entrains the air present between it and the internal wall of the front part 113 of the nozzle 109, thus creating an air suction in the nozzle 109 initiating an air flow, materialized by arrows in a thin line in FIG. 3, in the tube 103, this flow being supplied by the orifices 107. This air flow is channeled by the tube 103 and the nozzle 109 and injected into the jet of liquid CO, thus increasing the cross-section and the temperature of the liquid CO2 jet produced. The nozzle 109 therefore makes it possible to modify the opening of the CO jet,

liquid produced.

  When the operator wishes to suspend the ejection of liquid C02, he releases the arm 83 forming a trigger, and the spring 75 pushes the member 37 to the left in FIG. 1, bringing with it the lever 79 in rotation, the part 71 tapering gradually withdrawing from the part 47 of the bore 41 and the ball 61 being brought back by the spring 65 on its seat 63, where it again closes the passage between the

parts 47 and 49 of bore 41.

  The ball 61 therefore behaves like the shutter of a check valve for the flow of CO2

  expanded liquid, controlled by lever 79.

  During the production of a jet of liquid CO2, the liquid CO2 under pressure undergoes in the tube 29 a progressive expansion, thus avoiding on the one hand the production of carbon dioxide snow in the expansion means and in the means forming a valve, and on the other hand too great cooling in the body of the lance which could hinder or prevent the use

manual lance.

  The helical configuration of the tube 29 allows on the one hand to place in a reduced volume a length of tube sufficient to obtain the desired progressive relaxation, and on the other hand allows the tube 29 to

  adapt to the movement of the organ 37.

  The dimensions of the capillary tube 29 may

  vary depending on the intended power source.

  For example, for a low pressure liquid CO2 supply (P = 20 bars), its dimensions will be such that the liquid CO2 undergoes a pressure drop of 5 bars in

crossing it.

  Vent 102 allows, in the event of a leak in the

  body 1, the ejection of liquid CC2 under pressure.

  The means 9 for ejecting the Co, produced liquid are removable by unscrewing the ring 101 and are interchangeable. This makes it possible to modify, for example, the dimensional characteristics of the nozzle 91 for ejecting liquid CO 2 and of the nozzle 109 for air ducting, and thus to modify the range of characteristics of the jets that can be produced by the

  launches to adapt it to the type of cleaning envisaged.

  The length of the nozzle 109 can be such that, in its active air ducting position (FIG. 3), its front part 113 advances sufficiently beyond the front end 105 of the nozzle 91 so that a jet of liquid CO2 produced impacts the inner wall of this nozzle 109, which then forms a blunderbuss

of dry ice production.

  The positioning of the means 13 forming a valve downstream of the progressive expansion means 3 makes it possible to avoid delays in the production of the liquid CO2 jet when the operator presses or releases the arm.

83 forming relaxation.

  Alternatively, the valve means may consist of a solenoid valve 117 (Figure 4), preferably arranged upstream of the means 3 for progressive expansion. The lance described above is therefore perfectly suited to manual use, since an operator can, while holding and orienting the lance thanks to the body 1 forming a handle, control with the same hand the production of a jet of liquid CO2, and vary the characteristics of the liquid Co2 jet by moving the nozzle 109 using its

other hand.

  In particular, the heating of liquid CO2 by injection of an air flow can, in particular in the field of electronics, prove to be

  useful for limiting condensation of ambient air.

  Finally, the lance for producing a liquid CO2 jet according to the invention can be used

  manually in the open air or in glove boxes.

  As shown diagrammatically in FIG. 4, several lances according to the embodiment described or according to the aforementioned variant, can be combined to produce an apparatus for producing a jet of liquid CO2 for cleaning, for example automatically, surfaces. In such an apparatus, the valve forming means preferably consist of one or more solenoid valves 117, possibly common to several lances, for adjusting the flow rate of jets of liquid CO2 produced, and connected to one or more individual or common control units 119 of

  the opening of these solenoid valves 117.

  Such an apparatus could be incorporated in a surface cleaning installation comprising means 121 for moving a surface 123 to be cleaned with respect to the means for ejecting the different lances, and means 125 for evacuating the gaseous CO2 produced during the ejection of liquid CO2 may also be provided. Such an installation could also incorporate means 127 for heating the surface to limit the drawbacks associated with relatively low temperatures.

of the CO- liquid produced.

Claims (16)

  1. Lance for producing a jet of liquid CO2, comprising means (5) for connection to a source of liquid CO2 under pressure, means (3, 91) for expansion of the liquid CO2 under pressure and means (9) for ejecting the expanded liquid CO2 in a jet, characterized in that the means for expanding the liquid CO2 comprise means (3) for expanding progressive.   2. Lance according to claim 1, characterized in that the means (3) for progressive expansion comprise a capillary tube (29), especially wound in a helix.   3. Lance according to claim 1 or 2, characterized in that the ejection means (9) comprise a nozzle (91) for ejecting the expanded liquid CO2 provided with means (103, 109) for adjusting   opening of the liquid CO2 jet produced.   4. Lance according to claim 3, characterized in that said adjustment means comprise means (103, 109) for injecting an air flow into the jet of liquid CO2 produced, and adjustment means (109) flow rate of injected air.   5. Lance according to claim 4, characterized in that said adjustment means (103, 109) comprise a channeling member (109) adapted to surround an upstream part of the jet of liquid CO2 produced and thus create an air suction between the liquid CO2 jet and the channeling member. 6. Lance according to claim 5, characterized in that said adjustment means (103, 109) comprise a tube (103) surrounding the nozzle (91) for ejection from a distance and provided with an opening (107) for entry air, and a pipe nozzle (109) surrounding the ejection nozzle (91) at a distance, the pipe nozzle (109) being manoeuvrable and movable between a retracted position, in which it closes the opening (107) air inlet of the tube (103), and an active position in which it at least partially frees the air inlet opening (107) of the tube and in which a front part (113) of the nozzle of pipe is suitable for surrounding part of the liquid CO2 jet produced.   7. Lance according to claim 6, characterized in that in its active position, said front part (113) of the pipe nozzle (109)   forms a blister for producing dry ice.   8. Launches according to any of   claims 1 to 7, characterized in that the means   ejection (9) are interchangeable. 9. Launcher according to any one of   claims 1 to 8, characterized in that it   constitutes a manual lance comprising a body (1) forming a handle for orienting the jet of liquid CO produced, and in that it comprises means (13) forming a valve for adjusting the flow rate of the CO jet, produced liquid, controlled by a control member (79) which can be operated by the hand of an operator who   holds the body (1) forming a handle.   10. Lance according to claim 9, characterized in that the means (3) for progressive expansion comprise a capillary tube (29), and the means (13) forming a valve comprise a movable member (37) connected to one end of the capillary tube (29), and in that the capillary tube (29) is wound in a helix to adapt to the movement of said movable member (37). 11. Lance according to claim 9 or 10, characterized in that the means (13) forming a valve comprise a shut-off valve (61), located downstream of said progressive expansion means (3), and in that the control member (79) comprises a trigger (83) connected to an actuating trigger (85)   the shutter (61) of the shut-off valve.   12. Apparatus for producing a liquid CO2 jet, characterized in that it comprises on the one hand at least one lance according to any one of   claims 1 to 8, associated with at least one   solenoid valve for adjusting the flow rate of the liquid CO2 jet produced by the lance, and a control unit for   the opening of the or each solenoid valve.   13. Installation for cleaning the surface by a jet of liquid CO2, characterized in that it comprises an apparatus according to claim 12, and means for relative displacement of a surface to be cleaned by report to the spear.   14. Installation according to claim 13, characterized in that it further comprises means for evacuating the gaseous CO2 produced during ejection. liquid CO2.   15. Ejection means for a lance according to   any one of claims 1 to 11.   16. Ejection means according to claim, characterized in that they comprise a nozzle (91) for ejecting expanded liquid CO2, a body (87) for connection to the means (3) for progressive expansion of a lance, a ring (101) for mounting on the lance, a tube (103) surrounding the ejection nozzle (91) at a distance and provided with an air inlet opening (107), and a nozzle (109) for pipe surrounding the ejection nozzle (91) remotely, the pipe nozzle (109) being manoeuvrable and movable between a retracted position, in which it closes the air inlet opening (107) of the tube, and a active position in which it at least partially frees the air inlet opening (107) of the tube (103) and in which a front part (113) of the pipe nozzle (109) is adapted to surround a   part of the liquid CO2 jet produced.