JP5615248B2 - Dry ice snow injection device and dry ice snow injection method - Google Patents

Description

  The present invention relates to a dry ice snow injection device and a dry ice snow injection method.

  For example, a dry ice snow spraying device that sprays dry ice particles (dry ice snow) to remove foreign matter adhering to the surface of an electronic component because, for example, it is not necessary to dry the electronic component after cleaning. Is being used.

  For example, in Patent Document 1, an adapter is connected to a liquefied carbon dioxide supply nozzle to which a supply line from a liquefied carbon dioxide container filled with liquefied carbon dioxide and a supply line of an injection gas container filled with jetting gas are respectively connected. A dry ice snow spraying device is described having a body nozzle connected through the same.

  In the dry ice snow injection device described in Patent Document 1, the liquefied carbon dioxide supplied from the liquefied carbon dioxide container is jetted from the micro orifice provided in the liquefied carbon dioxide supply nozzle to the cylinder portion of the main body nozzle to adiabatic expansion. By being cooled, it becomes dry ice particles, and is sprayed as dry ice snow from the main body nozzle.

  However, in the dry ice snow injection device described in Patent Document 1, when the liquefied carbon dioxide gas is input from the atmosphere or the like until the liquefied carbon dioxide gas is taken out from the liquefied carbon dioxide gas container and guided to the main body nozzle, the liquefied carbon dioxide gas As a result, the liquefied carbon dioxide gas partially vaporizes, resulting in an unstable state. When liquefied carbon dioxide gas is injected from the micro orifice to the cylinder part of the main body nozzle in such an unstable state, dry ice snow is difficult to generate, which may hinder cleaning using dry ice snow. It was.

  Therefore, for example, in Patent Document 2 and Patent Document 3, by providing a cooling means until the liquefied carbon dioxide gas is guided from the liquefied carbon dioxide container to the main body nozzle, the liquefied carbon dioxide gas is brought into a supercooled state, An apparatus for generating dry ice snow more stably is described.

  Specifically, in the dry ice injection device described in Patent Document 2, a cooler is provided between the gas container and the injector, and the temperature of the liquefied carbon dioxide gas flowing into the injector is taken out of the gas container. For example, the temperature is adjusted to be 2 ° C. or more lower than the temperature of the liquefied carbon dioxide gas.

  Moreover, in the dry ice manufacturing apparatus described in Patent Document 3, a heat exchange chamber that is insulated is provided between a supply pipe that supplies liquefied carbon dioxide from a storage container that stores liquefied carbon dioxide and a dry ice generation nozzle. In the heat exchange chamber, the liquefied carbon dioxide is jetted from the jet nozzle connected to the branch supply path branched from the middle of the supply pipe to cool the supercooling heat exchanger, and the liquefied carbon dioxide is supercooled. Is described.

Utility Model Registration Gazette No. 2557383 JP 2007-160244 A JP 2010-105837 A

  In the dry ice injection device described in Patent Document 2, the cooling temperature of the liquefied carbon dioxide gas flowing into the injector is controlled by the temperature of the liquefied carbon dioxide gas taken out from the gas container. However, when a low temperature liquefied carbon dioxide gas such as −10 ° C. is taken out from the gas container, the temperature of the liquefied carbon dioxide gas rises due to heat input from the atmosphere or the like between the gas container and the cooler and evaporates. For this reason, there is a problem that the accurate temperature of the liquefied carbon dioxide gas cannot be measured, and the cooling temperature in the cooler cannot be sufficiently controlled.

  Also, in the dry ice production apparatus described in Patent Document 3, the liquefied carbon dioxide gas is based on the temperature difference between the temperature of the liquefied carbon dioxide gas at the inlet of the heat exchange chamber and the temperature of the liquefied carbon dioxide gas at the outlet of the heat exchange chamber. The cooling temperature is controlled. Therefore, for example, when the temperature of the supply pipe and the temperature measuring unit has risen to room temperature, such as when the dry ice production apparatus is started and after a long-time shutdown, the liquefied carbon dioxide gas is wasted until these are cooled. It was necessary to flow for a long time.

  Furthermore, in the devices described in Patent Document 2 and Patent Document 3, the sprayed dry ice snow has a reduced pressure when the dry ice snow is continuously sprayed for a long time because the pressure of the liquefied carbon dioxide storage container decreases. There has also been a problem that the impact pressure (cleaning pressure) on the object to be processed changes.

  In view of the above circumstances, an object of the present invention is to provide a dry ice snow device and a dry ice snow injection method capable of stably generating and injecting dry ice snow while suppressing waste of liquefied carbon dioxide. There is to do.

  The present invention relates to a carbon dioxide storage container that is a vacuum insulation container, a carbon dioxide supply path connected to the carbon dioxide storage container, a cooling unit provided in the carbon dioxide supply path, and a pressure provided in the carbon dioxide supply path. A measurement unit, a temperature measurement unit provided on the downstream side of the cooling unit of the carbon dioxide supply channel, a liquefied carbon dioxide injection unit provided on the downstream side of the temperature measurement unit of the carbon dioxide supply channel, a cooling unit, and a pressure measurement A control unit connected to each of the unit, the temperature measurement unit and the liquefied carbon dioxide injection unit, and the control unit controls the cooling of the carbon dioxide by the cooling unit based on the pressure of the carbon dioxide measured by the pressure measurement unit. Is a dry ice snow spraying device.

  Here, in the dry ice snow injection device of the present invention, the control unit is configured such that the saturation temperature T of the carbon dioxide gas at the pressure of the carbon dioxide gas measured by the pressure measurement unit and the temperature T ′ measured by the temperature measurement unit are: It is preferable to perform control for cooling the carbon dioxide gas by the cooling unit so as to satisfy the relationship of T ′ <T.

Further, in the dry ice snow jet apparatus of the present invention, the control unit, the temperature at which the pressure of the measured carbon dioxide under a pressure measuring unit is measured by the saturation temperature T ₁ of the temperature measuring unit of carbon dioxide gas when it is P ₁ T ₁ ′, the saturation temperature T ₂ of the carbon dioxide gas when the pressure of the carbon dioxide gas measured by the pressure measurement unit is P ₂ lower than P _1, and the temperature T ₂ ′ measured by the temperature measurement unit, Control is performed to cool the carbon dioxide gas by the cooling unit so as to satisfy the relationship of T ₁ ′ <T ₁ , T ₂ ′ <T ₂ , and | T ₁ ′ −T ₁ | <| T ₂ ′ −T ₂ |. It is preferable.

  Furthermore, the present invention includes a step of measuring the pressure of carbon dioxide, a step of cooling the carbon dioxide, and a step of injecting carbon dioxide after the step of cooling. Is a dry ice snow injection method in which the carbon dioxide gas is cooled so that the saturation temperature T of the carbon dioxide gas and the temperature T ′ of the carbon dioxide gas after the cooling step satisfy the relationship of T ′ <T.

Here, in the method of injection dry ice snow of the present invention, in the step of cooling, the temperature T ₁ of the carbon dioxide gas after the step of cooling the saturation temperature T ₁ of the carbon dioxide when the pressure of the carbon dioxide gas is P ₁ ', And the saturation temperature T ₂ of the carbon dioxide gas when the pressure of the carbon dioxide gas is P ₂ lower than P ₁ and the temperature T ₂ ' of the carbon dioxide gas after the cooling step are T ₁ '<T ₁ , and It is preferable to cool the carbon dioxide gas so as to satisfy the relationship of T ₂ ′ <T ₂ and | T ₁ ′ −T ₁ | <| T ₂ ′ −T ₂ |.

  According to the present invention, it is possible to provide a dry ice snow device and a dry ice snow injection method that can suppress the waste of liquefied carbon dioxide gas and stably generate and inject dry ice snow.

It is a figure which shows the typical structure of an example of the dry ice snow injection apparatus of this invention. It is a flowchart of an example of the dry ice snow injection method using the dry ice snow injection apparatus shown in FIG.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

  In FIG. 1, the typical structure of an example of the dry ice snow injection apparatus of this invention is shown. A dry ice snow injection device shown in FIG. 1 includes a liquefied carbon dioxide storage container 1 that stores liquefied carbon dioxide gas, and a liquefied carbon dioxide supply path 5 that is connected to the liquefied carbon dioxide storage container 1 and serves as a liquefied carbon dioxide flow path. It has. Further, a pressure measuring unit 7 for measuring the pressure of the liquefied carbon dioxide gas, a cooling unit 11 for cooling the liquefied carbon dioxide gas, and the passage of the cooling unit 11 from the upstream side to the downstream side of the liquefied carbon dioxide supply path 5 A temperature measuring unit 10 for measuring the temperature of the later liquefied carbon dioxide gas and a liquefied carbon dioxide gas injection unit 12 for injecting liquefied carbon dioxide gas such as an on-off valve are provided in this order. Further, the pressure measurement unit 7, the temperature measurement unit 10, and the liquefied carbon dioxide injection unit 12 are each connected to a control unit 8 for controlling these units. Note that the pressure measurement unit 7 may be provided not on the upstream side of the cooling unit 11 but on the downstream side.

  The liquefied carbon dioxide supply path 5 is provided with a refrigerant flow path 16 serving as a flow path for the refrigerant 17 of the cooling unit 11. In the cooling zone 9 of the liquefied carbon dioxide supply path 5 to which the refrigerant flow path 16 is attached. The liquefied carbon dioxide gas 3 and the refrigerant 17 exchange heat, and the liquefied carbon dioxide gas 3 is cooled.

  A throttle unit 14 for generating dry ice snow such as an orifice is provided on the downstream side of the liquefied carbon dioxide injection unit 12. One end of a dry ice snow supply path 15 for supplying dry ice snow generated by jetting liquefied carbon dioxide gas is connected to the throttle unit 14, and an injection nozzle 21 is connected to the other end of the dry ice snow supply path 15. It is connected. Here, the outer peripheral surface of the dry ice snow supply path 15 is covered with a heat insulating material 19, and heat exchange between the dry ice snow passing through the dry ice snow supply path 15 and the external atmosphere is blocked.

  1 includes an injection gas storage container 2 that stores an injection gas, and an injection gas supply path that is connected to the injection gas storage container 2 and serves as a flow path for the injection gas. The injection gas supply path 6 is provided with an injection gas injection unit 13 for injecting an injection gas such as an on-off valve.

  In addition, an injection gas supply passage 20 with a heater is provided on the downstream side of the injection gas injection unit 13, and the downstream end of the injection gas supply passage 20 with a heater is attached to an injection nozzle 21. . Here, the outer peripheral surface of the supply path 20 for the injection gas with heater is covered with a heat insulating material 22.

  In addition, a part of the liquefied carbon dioxide supply path 5, the pressure measurement unit 7, the control unit 8, the cooling unit 11, the temperature measurement unit 10, the liquefied carbon dioxide injection unit 12, the throttle unit 14, a part of the heat insulating material 19, and for injection A part of the gas supply path 6 and the gas injection unit 13 for injection are respectively accommodated in the outer wall 18 of the dry ice snow injection device shown in FIG.

  Hereinafter, an example of a method for injecting dry ice snow using the dry ice snow injection device shown in FIG. 1 will be described.

  First, the liquefied carbon dioxide 3 is supplied from the liquefied carbon dioxide storage container 1 to the liquefied carbon dioxide supply path 5. The liquefied carbon dioxide 3 supplied from the liquefied carbon dioxide storage container 1 to the liquefied carbon dioxide supply path 5 enters the inside of the outer wall 18 of the apparatus through the liquefied carbon dioxide supply path 5, and the pressure measurement unit 7 Is measured.

  Next, the liquefied carbon dioxide gas that has passed through the pressure measurement unit 7 is cooled when passing through the cooling zone 9, and the temperature is measured by the temperature measurement unit 10 provided on the downstream side of the cooling zone 9.

  Next, the liquefied carbon dioxide 3 after passing through the temperature measuring unit 10 is injected into the dry ice snow supply path 15 by the liquefied carbon dioxide injection unit 12 through the throttle unit 14. The liquefied carbon dioxide 3 injected from the throttle unit 14 to the dry ice snow supply path 15 expands in the dry ice snow supply path 15, is cooled to become dry ice snow, and is introduced into the injection nozzle 21.

  Also, the injection gas 4 from the injection gas storage container 2 passes through the injection gas supply path 6 and is injected by the injection gas injection unit 13 into the injection gas supply path 20 with heater, and the injection gas supply path with heater 20 is introduced into the injection nozzle 21 while the temperature of the injection gas 4 is adjusted. As the injection gas 4, for example, a reaction inert gas such as dry air, nitrogen gas, or carbon dioxide gas can be used.

  The dry ice snow introduced into the injection nozzle 21 is injected from the opening of the injection nozzle 21 together with the injection gas 4 introduced into the injection nozzle 21.

  Here, in the dry ice snow injection device shown in FIG. 1, the control unit 8 controls the cooling of the liquefied carbon dioxide gas 3 by the cooling unit 11 based on the pressure of the liquefied carbon dioxide gas 3 measured by the pressure measuring unit 7. It is characterized by doing.

  FIG. 2 shows a flowchart of an example of a dry ice snow injection method using the dry ice snow injection device shown in FIG. First, as shown in step S <b> 1, the pressure of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 is measured by the pressure measurement unit 7. Information on the pressure of the liquefied carbon dioxide gas 3 measured by the pressure measurement unit 7 is transmitted from the pressure measurement unit 7 to the control unit 8.

  Next, as shown in step S <b> 2, the control unit 8 calculates the saturation temperature T of the liquefied carbon dioxide gas 3 at the pressure from the information on the pressure of the liquefied carbon dioxide gas 3.

  Next, as shown in step S <b> 3, the temperature measuring unit 10 measures the temperature T ′ of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9. Information on the temperature T ′ of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 measured by the temperature measurement unit 10 is transmitted from the temperature measurement unit 10 to the control unit 8.

  As shown in step S4, the control unit 8 determines that the saturation temperature T before passing through the cooling zone 9 and the temperature T ′ of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 are T ′ <T. Determine whether or not

  When the control unit 8 determines that the relationship of T ′ <T is not satisfied, the control unit 8 operates the cooling unit 11 to cool the liquefied carbon dioxide gas 3 as shown in step S5. Then, the temperature of the liquefied carbon dioxide gas 3 is lowered. The cooling temperature of the liquefied carbon dioxide gas 3 by the cooling unit 11 can be adjusted by, for example, increasing or decreasing the refrigerant 17 supplied from the cooling unit 11 to the refrigerant flow path 16. Further, in the cooling zone 9, the evaporated portion of the liquefied carbon dioxide gas 3 can be condensed and returned to the liquefied carbon dioxide gas 3.

  On the other hand, when the control unit 8 determines that the relationship of T ′ <T is satisfied, the control unit 8 operates the liquefied carbon dioxide injection unit 12 to operate the throttle unit 14 as shown in step S6. The liquefied carbon dioxide gas 3 can be supplied to the dry ice snow supply path 15 via the, and the dry ice snow can be injected from the injection nozzle 21. Note that the cooling temperature of the liquefied carbon dioxide gas 3 can be set in advance in the control unit 8 without calculating the saturation temperature T from the pressure of the liquefied carbon dioxide gas 3 measured by the pressure measuring unit 7. The cooling temperature at each pressure may be set to a numerical value that satisfies the relationship of T ′ <T and programmed.

  As described above, in the dry ice snow injection device shown in FIG. 1, the cooling temperature of the liquefied carbon dioxide gas 3 is based on the pressure of the liquefied carbon dioxide gas 3 instead of the temperature of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9. Is controlling.

  Therefore, in the dry ice snow injection device shown in FIG. 1, even if the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 is in a liquid state, it is evaporated and vaporized by heat input from the external atmosphere or the like. But the pressure can be monitored. Therefore, since the cooling temperature of the liquefied carbon dioxide gas 3 is controlled based on the monitored pressure even when the apparatus is started up and after a long-time stop, the liquefaction is caused for cooling the liquefied carbon dioxide gas supply path 5 and the like. There is no need to waste carbon dioxide for a long time.

  Further, the temperature of the liquefied carbon dioxide gas 3 cooled in the cooling zone 9 can be controlled to a temperature suitable for generating dry ice snow based on the monitored pressure.

  Therefore, in the dry ice snow injection device shown in FIG. 1, it is possible to suppress the waste of the liquefied carbon dioxide gas 3 and stably generate and inject dry ice snow.

  Table 1 below shows the pressure P (MPaG) of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9, the saturation temperature T (° C.) when the pressure of the liquefied carbon dioxide gas 3 is P, and after passing through the cooling zone 9. An example of the relationship with the temperature T ′ (° C.) of the liquefied carbon dioxide gas 3 is shown. Here, the cooling temperature of the liquefied carbon dioxide gas 3 in the cooling zone 9 can be set to −10 ° C. to −56.6 ° C., for example.

  Further, the pressure of the liquefied carbon dioxide gas 3 supplied from the liquefied carbon dioxide gas storage container 1 gradually decreases as the dry ice snow is injected.

Here, the saturation temperature of the liquefied carbon dioxide gas 3 when the pressure of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 is P ₁ is T _1, and the temperature of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 is T ₁ '. Further, the saturation temperature of the liquefied carbon dioxide gas 3 when the pressure of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 after the pressure is lowered from P ₁ is P ₂ (P ₂ <P ₁ ) is defined as T ₂ , The temperature of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 is defined as T ₂ ′. At this time, the control unit 8 sets the cooling unit so as to satisfy the relationship of T ₁ ′ <T ₁ , T ₂ ′ <T ₂ , and | T ₁ ′ −T ₁ | <| T ₂ ′ −T ₂ |. 11 is preferably used to control the cooling of the liquefied carbon dioxide gas 3. As a result, even when the pressure of the liquefied carbon dioxide gas 3 supplied from the liquefied carbon dioxide storage container 1 is reduced and the flow rate is reduced due to the injection of dry ice snow, the liquid is liquefied in accordance with the decrease in the flow rate. By lowering the cooling temperature of the carbon dioxide gas 3, it is possible to suppress a decrease in the amount of dry ice snow produced, so that dry ice snow can be produced and injected continuously and stably.

For example, as shown in Table 2 below, when the pressure P ₁ of the liquefied carbon dioxide gas 3 is 2.3 MPaG (gauge pressure) (saturation temperature T ₁ = −13.4 ° C.), it passes through the cooling zone 9. The liquefied carbon dioxide gas 3 is cooled so that the temperature T ₁ ′ of the later liquefied carbon dioxide gas 3 becomes −15 ° C. At this time, | T ₁ '-T ₁ | which is an absolute value of (T ₁ ' -T ₁ ) is 1.6 ° C.

On the other hand, when the pressure P ₂ of the liquefied carbon dioxide gas 3 is 1.5 MPaG (saturation temperature T ₂ = −26.6 ° C.), the temperature T ₂ ′ of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 is − The liquefied carbon dioxide gas 3 is cooled to 35 ° C. At this time, | T ₂ '-T ₂ | which is an absolute value of (T ₂ ' -T ₂ ) is 8.4 ° C.

  Further, as the liquefied carbon dioxide storage container 1, for example, a cylinder (cylinder), LGC (general low temperature liquefied gas container), CE (cold evaporator), or the like can be used. Especially, as the liquefied carbon dioxide gas storage container 1, it is preferable to use a large vacuum heat insulating container such as LGC or CE because the frequency of container replacement can be greatly reduced. In addition, the pressure of the liquefied carbon dioxide gas filled when using a vacuum heat insulation container as the liquefied carbon dioxide gas storage container 1 can be 0.6 MPaG-2.45 MPaG, for example.

  In the present specification, the “vacuum heat insulating container” means a liquefied gas storage container capable of suppressing heat in and out of the container by a vacuum space provided in at least a part of the container. The liquefied carbon dioxide storage container 1 may be a simply insulated container similar to a vacuum insulated container.

  Table 3 below shows the type of the liquefied carbon dioxide storage container 1, the pressure of the liquefied carbon dioxide gas (MPaG) filled in the liquefied carbon dioxide storage container 1, and the liquefied carbon dioxide gas filled in the liquefied carbon dioxide storage container 1. The relationship with the saturation temperature (degreeC) in a pressure is shown.

  In this specification, “liquefied carbon dioxide” is described, but “liquefied carbon dioxide” is not limited to being all in a liquefied state, and a part thereof is in a vaporized state. It is also included.

  In Table 4, the dry ice snow injection device (Example) of the present invention, the dry ice injection device described in Patent Document 2 (Comparative Example 1), and the dry ice production device described in Patent Document 3 (Comparative Example 2) Compare the time until accurate cooling control can be started.

  In the column of the example of Table 4, using the apparatus of FIG. 1 of the present application, the liquefied carbon dioxide 3 at temperatures near normal temperature and −10 ° C. or lower is taken out from the liquefied carbon dioxide storage container 1 which is a vacuum heat insulating container. The time until accurate cooling control of the cooling unit 11 by the control unit 8 can be started in a state where the liquefied carbon dioxide injection unit 12 is closed is shown.

  In the column of Comparative Example 1 in Table 4, liquefied carbon dioxide gas at a predetermined temperature is taken out from the gas container using a device provided with a throttle means between the cooler and the injector of FIG. The time until accurate cooling control can be started in a state where the means is opened or closed is shown.

  In the column of Comparative Example 2 in Table 4, the apparatus shown in FIG. 1 of Patent Document 3 is used to take out liquefied carbon dioxide gas at a predetermined temperature from the storage container and accurately open or close the stop solenoid valve. The time until the start of proper cooling control is shown.

  As shown in Table 4, in the embodiment, since accurate cooling control can be started from the time when the liquefied carbon dioxide gas 3 flows into the pressure measuring unit 7, the liquefied carbon dioxide gas injection unit 12 is closed and the gas flow is reduced. Even in the absence of the liquefied carbon dioxide gas taken out from the liquefied carbon dioxide storage container 1 to the liquefied carbon dioxide gas supply path 5, the temperature can be instantly (within 1 second) accurately cooled regardless of whether the temperature of the liquefied carbon dioxide gas is near room temperature or below -10 ° C. Control can be started.

  In the embodiment, as a matter of course, when the liquefied carbon dioxide injection unit 12 is opened and there is a gas flow, accurate cooling control can be started instantaneously (within 1 second).

  Therefore, in the embodiment, since the control of the cooling temperature can be started without wastefully flowing the gas with the liquefied carbon dioxide injection unit 12 closed, it is possible to inject dry ice snow at any time. Can do.

  On the other hand, in Comparative Example 1, the cooling of the liquefied carbon dioxide gas is controlled so that the temperature of the liquefied carbon dioxide gas flowing into the injector is lower by, for example, 2 ° C. or more than the temperature of the liquefied carbon dioxide gas taken out from the gas container. For this reason, when the throttle means is closed and there is no gas flow, the temperature of the liquefied carbon dioxide gas flowing into the injector cannot be measured, so that accurate cooling control cannot be started.

  Further, in Comparative Example 1, when the throttle means is opened and the gas flow is present, accurate cooling control can be started from the time when the liquefied carbon dioxide gas flows into the temperature sensor, so that the gas is taken out from the gas container. When the temperature of the liquefied carbon dioxide gas is near room temperature, accurate cooling control can be started, but the liquefied carbon dioxide gas flowed out from the gas container is small and the liquefied carbon dioxide gas evaporates before reaching the temperature sensor. Therefore, accurate cooling control cannot be started.

  In Comparative Example 2, when the stop solenoid valve is closed and there is no gas flow, liquefied carbon dioxide cannot be ejected from the ejection nozzle installed downstream of the stop solenoid valve. Cooling control cannot be started.

  In Comparative Example 2, when the stop solenoid valve is opened and the gas flow is present, accurate control of the cooling temperature can be started from the time when the liquefied carbon dioxide flows into the temperature sensor. When the temperature of the liquefied carbon dioxide taken out from the container is around room temperature, it takes several tens of seconds until accurate cooling control can be started. Even when the temperature is -10 ° C. or lower, the temperature sensor liquefies. Although the control of the cooling temperature can be started from the time when carbon dioxide flows, it is necessary to cool the device by flowing a large amount of liquefied carbon dioxide. It takes seconds to a few minutes.

  In the “gas flow” column of Table 4, “None” means that the liquefied carbon dioxide gas injection unit 12, the throttle means or the stop solenoid valve is closed and there is no liquefied carbon dioxide flow. In addition, the notation “present” means that the liquefied carbon dioxide gas flow is present because the liquefied carbon dioxide injection unit 12, the throttle means or the stop electromagnetic valve is opened.

  In the column of “Supply liquefied carbon dioxide gas temperature” in Table 4, the temperature of the liquefied carbon dioxide gas taken out from the liquefied carbon dioxide gas storage container 1, gas container or storage container is shown. This means that the temperature of the liquefied carbon dioxide gas cannot be measured by the temperature sensor regardless of the temperature of the liquid crystal.

<Example 1>
By spraying dry ice snow from the dry ice snow injection device shown in FIG. 1 onto a pressure measurement film (trade name: Fuji Prescale) manufactured by Fuji Photo Film Co., Ltd., the collision pressure of dry ice snow is measured and the collision pressure is measured. The maximum difference was calculated.

(Experimental conditions)
Liquefied carbon dioxide storage container 1: LGC
Throttle unit 14: Orifice Injection gas 4: Dry air, 0.55 MPaG, 30 ° C.
Laboratory temperature: 20-25 ° C
Specifically, first, the liquefied carbon dioxide 3 was supplied from the liquefied carbon dioxide storage container 1 made of LGC, which is a vacuum heat insulating container, to the liquefied carbon dioxide supply path 5. Then, the pressure P of the liquefied carbon dioxide 3 supplied from the liquefied carbon dioxide storage container 1 to the liquefied carbon dioxide supply path 5 is measured by the pressure measuring unit 7, and the control unit 8 measures the liquefied carbon dioxide 3 at the pressure P. The saturation temperature T was calculated. Table 5 shows the pressure P (MPaG) of the liquefied carbon dioxide gas 3 measured by the pressure measurement unit 7 and the saturation temperature T (° C.) at each pressure P.

  Then, the liquefied carbon dioxide gas 3 that has passed through the pressure measuring unit 7 is cooled in the cooling zone 9, and the temperature T of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 by the temperature measuring unit 10 provided on the downstream side of the cooling zone 9. 'Measured. Table 5 shows the temperature T ′ (° C.) of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 at each pressure P.

  Here, in Example 1, the control unit 8 is set such that the difference (T′−T) between the temperature T ′ of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 and the saturation temperature T is −2 ° C. Controlled the cooling unit 11 to cool the liquefied carbon dioxide gas 3.

  Thereafter, the liquefied carbon dioxide gas 3 is jetted from the liquefied carbon dioxide jet unit 12 through the throttle unit 14 to the dry ice snow supply passage 15 and is injected into the dry ice snow supply passage 15 as dry ice snow from the jet nozzle 21 for dry air. The gas 4 was sprayed for 5 seconds perpendicularly (distance 20 mm) to the pressure measuring film.

  And the collision pressure (MPa) of dry ice snow was measured from the color change of the pressure measurement film after dry ice snow injection, and the maximum difference (MPa) of the collision pressure was calculated. The results are shown in Table 5.

  As shown in Table 5, the difference (T′−T) between the temperature T ′ of the liquefied carbon dioxide gas 3 after passing through the cooling zone 9 and the saturation temperature T calculated based on the pressure P is −2 ° C. In Example 1 in which the cooling of the liquefied carbon dioxide gas 3 was controlled, the pressure P of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 was 2.3 (MPaG), 1.9 (MPaG) and 1.5. When the pressure was (MPaG), the collision pressure was 41 (MPa), 43 (MPa), and 45 (MPa), respectively, and the maximum difference in the collision pressure was 4 (MPa).

<Example 2>
The saturation temperatures when the pressure of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 is P ₁ and P ₂ (P ₂ <P ₁ ) are T ₁ and T ₂ , respectively, and the liquefied carbon dioxide after passing through the cooling zone 9 When the temperatures of the gas 3 are T ₁ ′ and T ₂ ′, respectively, T ₁ ′ <T ₁ , T ₂ ′ <T ₂ , and | T ₁ ′ −T ₁ | <| T ₂ ′ −T ₂ | The collision pressure (MPa) of dry ice snow was measured in the same manner as in Example 1 except that the control unit 8 controlled the cooling unit 11 to cool the liquefied carbon dioxide gas 3 so as to satisfy the above relationship. The maximum difference (MPa) in collision pressure was calculated. The results are shown in Table 5.

  As shown in Table 5, in Example 2 in which the cooling of the liquefied carbon dioxide gas 3 was controlled as described above, the pressure P of the liquefied carbon dioxide gas 3 before passing through the cooling zone 9 was 2.3 (MPaG), 1.9. The collision pressures at (MPaG) and 1.5 (MPaG) were 42 (MPa), 42 (MPa) and 43 (MPa), respectively, and the maximum difference between the collision pressures was 1 (MPa).

<Reference example>
The experiment was performed in the same manner as in Example 2 except that the cooling of the liquefied carbon dioxide gas was controlled so that the temperature T ′ of the liquefied carbon dioxide gas after cooling was constant at −35 ° C. The results are shown in Table 5.

  As shown in Table 5, in the reference example, the collision pressure when the pressure P of the liquefied carbon dioxide gas before cooling is 2.3 (MPaG), 1.9 (MPaG), and 1.5 (MPaG), respectively. 36 (MPa), 40 (MPa), and 43 (MPa), and the maximum difference in collision pressure was 7 (MPa).

<Evaluation>
As shown in Table 5, in Example 1 and Example 2, it was possible to generate and spray dry ice snow more stably than in the reference example. This is probably because, in the first and second embodiments, unlike the reference example, appropriate cooling control is performed based on the pressure of the liquefied carbon dioxide before cooling.

  Further, as shown in Table 5, in Example 2, it was possible to generate and spray dry ice snow more stably than in Example 1. This is because the amount of liquefied carbon dioxide flowing into the liquefied carbon dioxide jet unit 12 decreases as the inside of the liquefied carbon dioxide storage container 1 becomes lower in pressure, so by lowering the cooling temperature and increasing the degree of supercooling, This is probably because the production rate was increased and the amount of dry ice generated could be made substantially constant regardless of the change in pressure in the liquefied carbon dioxide storage container 1.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used in a dry ice snow spraying apparatus and a dry ice snow spraying method.

  1 liquefied carbon dioxide storage container, 2 injection gas storage container, 3 liquefied carbon dioxide gas, 4 injection gas, 5 liquefied carbon dioxide supply path, 6 injection gas supply path, 7 pressure measurement unit, 8 control unit, 9 cooling zone DESCRIPTION OF SYMBOLS 10 Temperature measurement unit, 11 Cooling unit, 12 Liquefied carbon dioxide injection unit, 13 Injection gas injection unit, 14 Throttle unit, 15 Dry ice snow supply path, 16 Refrigerant flow path, 17 Refrigerant, 18 Outer wall, 19 Thermal insulation, 20 supply path for spray gas with heater, 21 spray nozzle, 22 heat insulating material.

Claims (5)

A carbon dioxide storage container which is a vacuum insulation container;
A carbon dioxide gas supply path connected to the carbon dioxide gas storage container;
A cooling unit provided in the carbon dioxide supply path;
A pressure measurement unit provided in the carbon dioxide gas supply path;
A temperature measurement unit provided on the downstream side of the cooling unit of the carbon dioxide supply path;
A liquefied carbon dioxide injection unit provided on the downstream side of the temperature measurement unit of the carbon dioxide supply path;
A control unit connected to each of the cooling unit, the pressure measurement unit, the temperature measurement unit, and the liquefied carbon dioxide injection unit, and
The dry ice snow injection device, wherein the control unit controls the cooling of the carbon dioxide by the cooling unit based on the pressure of the carbon dioxide measured by the pressure measuring unit.   The control unit is configured so that the saturation temperature T of the carbon dioxide gas at the pressure of the carbon dioxide gas measured by the pressure measurement unit and the temperature T ′ measured by the temperature measurement unit satisfy a relationship of T ′ <T. The dry ice snow spraying device according to claim 1, wherein the cooling unit performs control to cool carbon dioxide gas. The control unit includes a saturation temperature T ₁ of carbon dioxide gas when the pressure of the carbon dioxide gas measured by the pressure measurement unit is P ₁ , a temperature T ₁ ′ measured by the temperature measurement unit, and the pressure measurement unit in the measured temperature T ₂ the pressure is measured at saturated temperature T ₂ and the temperature measuring unit of carbon dioxide gas when the a low P ₂ than P ₁ of the carbon dioxide gas 'and is, T _1' <T ₁ And T ₂ '<T ₂ and | T ₁ ' -T ₁ | <| T ₂ '-T ₂ | 2. A dry ice snow spraying device according to 2. Measuring the pressure of carbon dioxide,
A step of cooling carbon dioxide,
Injecting carbon dioxide gas after the cooling step,
In the cooling step, the carbon dioxide gas is cooled so that the saturation temperature T of the carbon dioxide gas at the measured pressure and the temperature T ′ of the carbon dioxide gas after the cooling step satisfy a relationship of T ′ <T. A dry ice snow injection method. In the cooling step,
When the carbon dioxide pressure is P ₁ , the carbon dioxide saturation temperature T ₁ , the carbon dioxide temperature T ₁ ′ after the cooling step, and the carbon dioxide pressure is P ₂ lower than P _1. The carbon dioxide gas saturation temperature T ₂ and the carbon dioxide gas temperature T ₂ ′ after the cooling step are T ₁ ′ <T ₁ , T ₂ ′ <T ₂ , and | T ₁ ′ −T ₁ | < The method for spraying dry ice snow according to claim 4, wherein the carbon dioxide gas is cooled so as to satisfy a relationship of | T ₂ ′ −T ₂ |.

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