JP7579558B2 - Dry Ice Blaster - Google Patents

Description

The present invention relates to a dry ice spraying device that sprays dry ice particles toward an object to clean the surface of the object.

Conventionally, there is known a device that introduces dry ice particles generated from liquefied carbon dioxide into a carrier gas flow and sprays them (see, for example, Patent Document 1).

In the dry ice spraying device disclosed in Patent Document 1, liquefied carbon dioxide supplied from a liquefied carbon dioxide container to a dry ice spraying nozzle is adiabatically expanded in a dry ice production tube to produce dry ice, and the produced dry ice is introduced into the flow of carrier gas supplied from the liquid nitrogen storage tank to the dry ice spraying nozzle and sprayed.

JP 2003-145429 A

In this type of device, which sprays dry ice particles toward an object to treat (clean, etc.) the surface of the object, it is usually required that the flow rate of the sprayed dry ice particles be constant in order to efficiently treat (clean, etc.) the surface of the object.

However, if the pressure when supplying liquefied carbon dioxide is low, the dry ice particles may clog the inside of the piping, causing the dry ice particles to be sprayed intermittently. That is, when dry ice particles are generated by the adiabatic expansion of liquefied carbon dioxide, large chunks of dry ice may be generated during the particle generation process. These large chunks of dry ice may then temporarily block the dry ice generation pipe. As a result, intermittent spray occurs, where sometimes dry ice particles are sprayed from the spray nozzle and sometimes they are not, and the surface of the target object may not be treated (cleaned, etc.) efficiently.

The present invention was devised in consideration of the above problems, and aims to provide a dry ice spraying device that can stably and continuously spray dry ice particles by preventing dry ice lumps from clogging the dry ice generation tube.

The dry ice spraying device according to the first aspect of the present invention comprises a liquefied carbon dioxide supply channel for supplying liquefied carbon dioxide, a nozzle for spraying the liquefied carbon dioxide supplied from the liquefied carbon dioxide supply channel, a dry ice generation tube having an expansion space formed therein for expanding the liquefied carbon dioxide sprayed from the nozzle to generate dry ice particles, a carrier gas supply channel for supplying carrier gas, and a spray member connected to the downstream side of the dry ice generation tube and combining the dry ice particles flowing out from the downstream side of the dry ice generation tube with the carrier gas supplied from the carrier gas supply channel to spray the combined mixture from a spray nozzle, and a heating means for heating the dry ice generation tube.

A dry ice sprayer with this configuration can provide a dry ice sprayer that can stably and continuously spray dry ice particles.

The dry ice spraying device according to the second aspect of the present invention is the dry ice spraying device according to the first aspect, in which the downstream side of the dry ice generation pipe and the spraying member are connected via a flexible tube, and the spraying member is connected to the downstream side of the flexible tube, and the dry ice particles flowing out from the downstream side of the flexible tube and the carrier gas supplied from the carrier gas supply path are merged and sprayed from the spray nozzle.

The dry ice spraying device according to the third aspect of the present invention is the dry ice spraying device according to the first or second aspect, in which the liquefied carbon dioxide supply path supplies the liquefied carbon dioxide to the nozzle at a pressure within 2 MPa ± 0.3 MPa.

The dry ice spraying device according to the fourth aspect of the present invention is a dry ice spraying device according to any one of the first to third aspects, which is provided with a temperature control unit that controls the heating temperature in the heating means so that the dry ice generating tube is at a predetermined temperature.

The fifth aspect of the dry ice sprayer of the present invention is a dry ice sprayer according to any one of the first to fourth aspects, in which the heating means has a heating element and a heat transfer member having thermal conductivity, and transfers the heat generated by the heating element to the dry ice generation tube via the heat transfer member.

The sixth aspect of the dry ice spraying device of the present invention is a dry ice spraying device according to any one of the first to fifth aspects, in which the heating means transfers heat by directly contacting the dry ice generating tube.

The seventh aspect of the dry ice spraying device of the present invention is the dry ice spraying device of the sixth aspect, in which the heating means transfers heat by directly contacting the upstream side of the dry ice generating tube.

The present invention provides a dry ice spraying device that can stably and continuously spray dry ice particles.

1 is a partial cross-sectional view showing a main part of a dry ice spraying device according to a first embodiment. FIG. 1 is a diagram showing an entire dry ice spraying device according to a first embodiment; FIG. 3 is an enlarged perspective view of the heating means according to the first embodiment, showing a manufacturing process of the heating means. FIG. 11 is a partial cross-sectional view showing the main parts of the dry ice jet according to the second embodiment. FIG. 13 is a diagram showing a main part of a dry ice spraying device according to a third embodiment.

The following describes a dry ice spraying device according to an embodiment of the present invention with reference to the drawings. As shown in FIG. 1, the dry ice spraying device 100 includes a liquefied carbon dioxide supply unit 3, a spray hole 6, a dry ice generating tube 7, a flexible tube 8, a carrier gas supply unit 9, a spray member 10, a heating means 20, a temperature control unit 50, etc.

As shown in FIG. 2, the liquefied carbon dioxide supply unit 3 includes a liquefied carbon dioxide supply path 31, a liquefied carbon dioxide storage unit 32, an on-off valve SV1, a gas-liquid separator 33, etc., and supplies liquefied carbon dioxide to the dry ice generation pipe 7.

The liquefied carbon dioxide storage unit 32 is a low-pressure storage unit that stores cooled liquefied carbon dioxide at a low pressure of approximately 2 MPa (e.g., 2 MPa ± 0.5 MPa). For example, a cryogenic container (LGC) or a storage tank (CE: cold evaporator) is used as the liquefied carbon dioxide storage unit 32. Since a large amount of liquefied carbon dioxide is used when cleaning a large object X, a container with a large capacity is often used as the liquefied carbon dioxide storage unit 32. The liquefied carbon dioxide is supplied from the liquefied carbon dioxide storage unit 32 to the liquefied carbon dioxide supply path 31 at a pressure of approximately 2 MPa (e.g., 2 MPa ± 0.3 MPa).

The liquefied carbon dioxide supply path 31 is formed by piping or the like from the liquefied carbon dioxide storage section 32 to the nozzle hole 6 formed in the orifice plate 4, and supplies liquefied carbon dioxide to the expansion space 71 in the dry ice production pipe 7 through the nozzle hole 6 of the orifice plate 4. On this liquefied carbon dioxide supply path 31, an on-off valve SV1 attached to the liquefied carbon dioxide storage section 32, a gas-liquid separator 33, etc. are provided.

The gas-liquid separator 33 separates the carbon dioxide gas generated in the liquefied carbon dioxide and discharges it from the liquefied carbon dioxide supply line 31. The gas-liquid separator 33 is provided upstream of the ejection hole 6 and close to the ejection hole 6 (for example, 100 mm to 500 mm upstream from the ejection hole 6).

The orifice plate 4 is formed of a thin plate (e.g., a circular plate with a thickness of 1 mm) with one or more ejection holes 6. This orifice plate 4 is provided at the boundary between the downstream end 31b of the liquefied carbon dioxide supply path 31 and the upstream end 7a of the dry ice generation pipe 7.

The ejection hole 6 is formed in the orifice plate 4, and ejects the liquefied carbon dioxide supplied from the liquefied carbon dioxide supply passage 31 into the expansion space 71 inside the dry ice generating tube 7. The ejection hole 6 has an inner diameter of, for example, 0.1 mm to 0.2 mm, and in this embodiment, one ejection hole 6 with an inner diameter of 0.18 mm is formed.

As shown in FIG. 1, the upstream end 7a of the dry ice generating pipe 7 is connected to the downstream end 31b of the liquefied carbon dioxide supply path 31 via the orifice plate 4, and an expansion space 71 is formed inside the pipe 7 to expand the liquefied carbon dioxide ejected from the ejection hole 6 of the orifice plate 4 to generate dry ice particles. The downstream end 7b of the dry ice generating pipe 7 is connected to the upstream end 8a of the flexible tube 8, and the outer diameter of the downstream end 7b of the dry ice generating pipe 7 is set to a predetermined size so that the liquefied carbon dioxide ejected from the ejection hole 6 into the expansion space 71 expands adiabatically to form dry ice particles. In other words, the cross-sectional area of the inside of the dry ice generating pipe 7 and the cross-sectional area of the ejection hole 6 formed in the orifice plate 4 are set to a predetermined ratio. The expansion space 71 is a space formed inside the dry ice production pipe 7 from the upstream end 7a to the downstream end 7b of the dry ice production pipe 7.

The flexible tube 8 has an upstream end 8a connected to the downstream end 7b of the dry ice generating tube 7, and the injection member 10 is connected to the downstream side. This flexible tube 8 delivers dry ice particles generated in the dry ice generating tube 7 to the injection member 10. The flexible tube 8 is made of a material having a certain degree of flexibility so that the injection member 10 connected to the downstream side can move freely relative to the object X. For example, Teflon (registered trademark) can be used as the material for the flexible tube 8. In this embodiment, the length of the flexible tube 8 is about 1 m to 2 m. In addition, a crimped ferrule lock joint or the like may be used to connect the flexible tube 8 and the dry ice generating tube 7 to ensure airtightness. In addition, on the downstream side of the flexible tube 8, a straight tube with no flexibility may be used downstream of the part connected to the injection member 10.

The injection member 10 is connected to the downstream side of the flexible tube 8. Inside the injection member 10, a junction space 101 is formed, and further, a flow path 102 is formed from the downstream end 8b of the flexible tube 8 toward the injection port 103. The injection member 10 injects dry ice particles from the injection port 103 onto the object X to be cleaned. Specifically, the injection member 10 merges the dry ice particles supplied from the flexible tube 8 and the carrier gas supplied from the carrier gas supply path 91 in the junction space 101, and injects the dry ice particles together with the carrier gas through the flow path 102 onto the object X to be cleaned (see FIG. 2). Since the injection member 10 is connected to the dry ice generating tube 7 via the flexible tube 8, it can move freely relative to the object X. The injection member 10 is used, for example, attached to an injection member moving device that moves relative to the surface of the object X. Examples of the injection member moving device include a robot arm and an XY stage (not shown).

2, the carrier gas supply unit 9 has an air pressure source 92, a carrier gas supply path 91, and an on-off valve SV2. The upstream end 91a of the carrier gas supply path 91 is connected to the air pressure source 92, and the downstream end 91b is connected to the merging space 101 inside the injection member 10, and the carrier gas sent from the air pressure source 92 is supplied to the injection member 10. The tube used for the carrier gas supply path 91 is not particularly limited. However, in order to make the injection member 10 movable relative to the object X, a flexible tube 93 is used for at least a part of the downstream side of the carrier gas supply path 91. The carrier gas supply path 91 is formed so as to supply the carrier gas toward the side of the flexible tube 8 in the merging space 101 inside the injection member 10. With this configuration, a flow of the carrier gas is formed in the merging space 101 in the same direction as the flow of the dry ice particles flowing out of the flexible tube 8, as shown in FIG. 1. In this embodiment, dry air is used as the carrier gas, but a gas with a low dew point temperature can be used as the carrier gas. In addition to the dry air, nitrogen gas, carbon dioxide gas, etc. may also be used.

In the confluence space 101, the carrier gas supplied from the carrier gas supply path 91 and the dry ice particles generated in the dry ice generation tube 7 join together. Specifically, in this confluence space 101, the dry ice particles flowing out from the downstream end 8b of the flexible tube 8 join the flow of the carrier gas flowing from the upstream side of the downstream end 8b of the flexible tube 8. The dry ice particles that join the carrier gas in the confluence space 101 pass through the flow path 102 and are sprayed from the nozzle 103 toward the object X to be cleaned.

The heating means 20 will be described below. The heating means 20 is provided to heat the dry ice generating tube 7. As shown in FIG. 3(a), the heating means 20 has a heating element 201 and a heat transfer member 202 having thermal conductivity. The heating means 20 heats the dry ice generating tube 7, thereby preventing the generation of excessively large chunks of dry ice that could cause clogging in the dry ice generating tube 7.

The heating element 201 may be, for example, an electric heater that generates heat when electricity is applied. The electric heater serving as the heating element 201 may be, for example, shaped like a straight rod, and is arranged parallel to the axial center of the dry ice generating tube 7.

The heat transfer member 202 is composed of, for example, a rectangular parallelepiped block divided into two parts, the first heat transfer member 2021 and the second heat transfer member 2022. The first heat transfer member 2021 and the second heat transfer member 2022 are connected in a state in which their connection surfaces face each other and are in surface contact, as shown in FIG. 3(b). The heating element 201 and the dry ice generating tube 7 are arranged parallel to each other and sandwiched between the first heat transfer member 2021 and the second heat transfer member 2022. A recess is formed on one or both of the connection surfaces of the first heat transfer member 2021 and the second heat transfer member 2022 in accordance with the shape of the side portion of the heating element 201 and the dry ice generating tube 7. By making it into such a shape, the area of contact between the heat transfer member 202 and the heating element 201 and the dry ice generating tube 7 can be increased, and heat can be efficiently transferred from the heating element 201 to the dry ice generating tube 7. The first heat transfer member 2021 and the second heat transfer member 2022 are fixed together using bolts (not shown), but the fixing means is not particularly limited.

The configuration of the heating means 20 is not limited to the above configuration. For example, it may be configured to blow hot air onto the dry ice generating tube 7, or to have the heating element 201 directly contact the dry ice generating tube 7. In other words, it is sufficient that the configuration heats the dry ice generating tube 7 so as to prevent excessively large lumps of dry ice from being generated inside the dry ice generating tube 7.

The heating means 20 may be configured to heat only a portion of the dry ice generating tube 7 (e.g., the upstream side from the midpoint in the longitudinal direction, or the upstream end 7a).

The temperature control unit 50 (see Figures 1 and 2) controls the heating temperature in the heating means 20 so that the temperature of the outer surface of the dry ice generating tube 7 becomes a predetermined temperature. Specifically, when the heating element 201 is an electric heater, the temperature control unit 50 controls the power supplied to the heating element 201. By controlling the power, the temperature of the heating element 201 is controlled, and the heating temperature of the dry ice generating tube 7 is controlled. Since the triple point of carbon dioxide, which is the intersection of the boiling line, melting line, and sublimation line, has a temperature of -56°C, it is desirable to prevent the temperature inside the dry ice generating tube 7 from falling below -56°C so that excessively large chunks of dry ice are not formed. In order to make the inside of the dry ice generating tube 7 at that temperature, it is desirable to keep the temperature of the outer surface of the dry ice generating tube 7 at a constant temperature, for example, about -20°C to -30°C. By doing so, the temperature control unit 50 controls the power supplied to the electric heater and controls the heating temperature of the heating means 20, so that the temperature of the outer surface of the dry ice generating tube 7 and therefore the temperature inside the dry ice generating tube 7 can be controlled to a desired temperature.

The following are some variations of this case:

As shown in FIG. 4, the dry ice spraying device 100A according to the second embodiment does not use a flexible tube 8, and the upstream end 10a of the spraying member 10 is directly connected to the downstream side of the dry ice generating pipe 7.

The heating means 20 in the dry ice jetting device 100A according to the second embodiment heats the portion of the dry ice generating tube 7 exposed from the jetting member 10. In the example shown in FIG. 4, the heating means 20 heats the portion of the dry ice generating tube 7 exposed from the jetting member 10, which is a predetermined distance upstream from the downstream end 7b of the dry ice generating tube 7 (e.g., a length equal to 1/2 the length of the dry ice generating tube 7).

The heating means 20 in the dry ice jetting device 100A according to the second embodiment is in direct contact with the surface of the dry ice generating tube 7. Specifically, the heat transfer member 202 is in direct contact with the surface of the dry ice generating tube 7.

As shown in FIG. 5, the dry ice jetting device 100B according to the third embodiment has multiple dry ice generating tubes 7. The multiple dry ice generating tubes 7 are arranged parallel to each other with their upstream ends 7a and downstream ends 7b oriented in the same direction.

In the dry ice jetting device 100B according to the third embodiment, it is preferable to use fewer heating means 20B than the number of dry ice generating tubes 7 for the multiple dry ice generating tubes 7. For example, it is possible to use one heating element 201B and one heat transfer member 202B, and have the heat transfer member 202B come into contact with all of the multiple dry ice generating tubes 7. In this way, all of the multiple dry ice generating tubes 7 can be heated by one heating means 20B. Furthermore, by reducing the number of heating means 20B, it is possible to prevent an increase in the space required for installing the heating means 20B.

The configuration of the multiple dry ice generating tubes 7 and the heating means 20B that heats each of them is not limited to the above configuration. In other words, any other configuration may be used as long as it can efficiently spray dry ice particles onto the target object X.

The present invention can be applied, for example, to a dry ice sprayer.

100, 100A, 100B Dry ice injection device 31 Liquefied carbon dioxide supply path 6 Jet hole 7 Dry ice generation tube 7a Downstream end (of dry ice generation tube) 71 Expansion space 8 Flexible tube 8b Downstream end (of flexible tube) 91 Carrier gas supply path 10 Injection member 101 Junction space 102 Flow path 103 Injection port 20 Heating means 201 Heat generating element 202 Heat transfer member 50 Temperature control unit

Claims (3)

a liquefied carbon dioxide supply line for supplying liquefied carbon dioxide;
an orifice plate having a nozzle hole formed therein for spraying the liquefied carbon dioxide supplied from the liquefied carbon dioxide supply passage;
A dry ice generating tube having an expansion space formed therein for expanding the liquefied carbon dioxide ejected from the ejection hole to generate dry ice particles;
a carrier gas supply path for supplying a carrier gas;
an injection member connected to the downstream side of the dry ice generating pipe, which joins the dry ice particles flowing out from the downstream side of the dry ice generating pipe with the carrier gas supplied from the carrier gas supply path and injects the mixed gas from an injection port;
Equipped with
A heating means for heating the dry ice generating tube is provided,
The orifice plate is provided at a boundary between a downstream end of a pipe forming the liquefied carbon dioxide supply path and an upstream end of the dry ice production pipe,
The heating means transfers heat by directly contacting the dry ice generating tube with a surface thereof without directly contacting the piping forming the liquefied carbon dioxide supply path and the orifice plate,
The heating means includes a heating element and a heat transfer member having thermal conductivity.
The heat transfer member is a block divided into two parts, a first heat transfer member and a second heat transfer member, and the heating element and the dry ice generating tube are sandwiched between the first heat transfer member and the second heat transfer member in a state parallel to each other,
The heating means transfers heat generated by the heating element to the dry ice generating tube via the heat transfer member,
The heating means heats only the upstream side of the intermediate position in the longitudinal direction of the dry ice generating pipe,
A temperature control unit is provided to control the heating temperature in the heating means so that the temperature of the outer surface of the dry ice generating tube is between −20° C. and −30° C.
A dry ice spraying device. 2. The dry ice jetting device according to claim 1,
The downstream side of the dry ice generating pipe and the injection member are connected via a flexible tube,
The ejection member is connected to the downstream side of the flexible tube, and ejects the dry ice particles flowing out from the downstream side of the flexible tube and the carrier gas supplied from the carrier gas supply path from an ejection port by joining the dry ice particles.
A dry ice spraying device. 3. The dry ice jetting device according to claim 1,
The liquefied carbon dioxide supply path supplies the liquefied carbon dioxide to the nozzle at a pressure of 2 MPa ± 0.3 MPa.
A dry ice spraying device.

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