JP4166847B2 - Dry ice production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing ZoSo location of dry ice and, more particularly, to manufacturing ZoSo place the dry ice by adiabatic expansion of liquefied carbon dioxide.
[0002]
[Prior art]
Dry ice is manufactured by ejecting liquefied carbon dioxide from a nozzle and adiabatic expansion, but liquefied carbon dioxide supplied from a liquefied carbon dioxide supply source (liquefied carbon dioxide storage tank (cylinder)) Some are vaporized and in a gas-liquid mixed state. If this is supplied to the nozzle as it is, the generation efficiency and stability of dry ice will be reduced. Only liquid carbon dioxide gas is supplied to the nozzle. That is, the dry ice production apparatus generally includes a gas-liquid separator on the upstream side of the nozzle, and supplies the carbon dioxide gas separated from the gaseous carbon dioxide gas by the gas-liquid separator to the nozzle. Dry ice is manufactured by adiabatic expansion of liquid carbon dioxide gas by spraying into a cylinder whose lower end is called a snow horn.
[0003]
The gas-liquid separator used in the conventional dry ice production apparatus has a tank shape as described in, for example, JP-A-4-87927 and JP-A-6-293508. The gas-liquid separated liquid carbon dioxide is extracted from the bottom of the tank, and gaseous carbon dioxide is extracted from the top of the tank.
[0004]
[Problems to be solved by the invention]
However, in the tank-shaped gas-liquid separator, when the amount of liquid stored in the tank decreases and the liquid level becomes low (the liquid depth is shallow), the liquid level is reduced by the inflow of liquefied carbon dioxide from the liquefied carbon dioxide supply source. When the carbon dioxide gas is entrained in the liquid carbon dioxide and the gaseous carbon dioxide is mixed with the liquid carbon dioxide, it may flow out of the gas-liquid separator and be supplied to the nozzle. Could adversely affect the stable production.
[0005]
Thus, the present invention can reliably perform gas-liquid separation of the liquefied carbon dioxide gas supplied from the liquefied carbon dioxide gas supply source, and stably and efficiently produce dry ice by ejecting only the liquid carbon dioxide gas from the nozzle. is an object of the present invention to provide a manufacturing ZoSo location of dry ice that can be.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a dry ice production apparatus of the present invention is a dry ice production apparatus comprising: a cylindrical body having an open lower end; and a nozzle for adiabatic expansion by ejecting liquefied carbon dioxide into the cylindrical body. An inclined pipe is provided in a spiral shape on the outer periphery of the cylindrical body, and the inclined pipe is connected to a liquefied carbon dioxide supply pipe for supplying liquefied carbon dioxide gas from a liquefied carbon dioxide supply source. A gas carbon-liquid separated extraction section is provided, and a liquid carbon dioxide supply pipe for supplying gas-liquid separated liquid carbon dioxide to the nozzle is connected to the lower portion of the inclined pipe .
[0008]
Furthermore, in the present invention, the pre-Symbol inclined tube, that it is a larger diameter than the liquefied carbon dioxide supply pipe connecting the said inclined pipe liquefied carbon dioxide supply source, it was or, wherein the inclined tubes, the tubular body It is characterized by being provided in a spiral shape on the outer periphery.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 to 3 show an embodiment of the dry ice production apparatus of the present invention. FIG. 1 is a schematic view of the dry ice production apparatus, and FIG. 2 is a schematic view showing a gas-liquid separation state in an inclined pipe. 3 is a cross-sectional plan view showing an example of a connection state between the inclined pipe and the liquefied carbon dioxide supply pipe.
[0010]
The dry ice production apparatus includes a snow horn 2 provided with a nozzle 1 for ejecting liquid carbon dioxide, an inclined pipe 3 that performs gas-liquid separation to obtain the liquid carbon dioxide supplied to the nozzle 1, and liquefied carbon dioxide as a raw material. A liquefied carbon dioxide gas storage tank 4 for supplying gas, a liquefied carbon dioxide gas supply pipe 5 for supplying the liquefied carbon dioxide gas in the liquefied carbon dioxide gas storage tank 4 to the inclined pipe 3, and a gaseous carbon dioxide gas separated in the inclined pipe 3 A gaseous carbon dioxide exhaust pipe 6 for extraction, a liquid carbon dioxide supply pipe 7 for supplying the liquid carbon dioxide separated in the inclined pipe 3 to the nozzle 1, and a liquid level in the inclined pipe 3 are detected. A differential pressure type liquid level gauge 8, an automatic valve 9 for controlling the supply of liquid carbon dioxide to the nozzle 1, and an automatic valve 10 and a pressure holding valve 11 for controlling the amount of gaseous carbon dioxide discharged. Is formed.
[0011]
The snow horn 2 is composed of a cylindrical cylindrical body 2a and a substantially hemispherical head 2b. The snow horn 2 is arranged so that the opening is downward with the axis of the cylindrical body 2a as a vertical direction. The nozzle 1 is provided. In addition, the installation number and arrangement position of the nozzle 1 which ejects liquid carbon dioxide gas, and the ejection direction can be arbitrarily set, and may be provided in the cylindrical body 2a. Moreover, what is necessary is just to set suitably the shape of a snow horn 2, a diameter, length, etc. according to required dry ice manufacturing capability.
[0012]
The inclined pipe 3 is a gas generated by evaporating a part of the liquefied carbon dioxide supplied from the liquefied carbon dioxide storage tank 4 via the liquefied carbon dioxide supply pipe 5 by heat intrusion into the liquefied carbon dioxide supply pipe 5. It is for separating carbon dioxide, and is formed by a pipe having a diameter larger than that of the liquefied carbon dioxide supply pipe 5, and is installed so as to surround the outer periphery of the snow horn 2 in a spiral shape with a predetermined inclination angle. The pipe diameter and inclination angle of the inclined pipe 3 are such that the gas-liquid mixed carbon dioxide flowing into the inclined pipe 3 flows in a laminar flow state, and as shown in FIG. And the amount of carbon dioxide G in the gas-liquid mixed state is set so that the gaseous carbon dioxide G flows upward in the upper part of the pipe.
[0013]
For example, when the flow rate of carbon dioxide gas in a gas-liquid mixed state is large, the diameter of the inclined tube 3 is increased so that the gas-liquid separation in the inclined tube 3 can be performed for a sufficient time to increase the flow rate in the tube. What is necessary is just to make low, to make inclination-angle small, or to lengthen length.
[0014]
The form of the inclined pipe 3 varies depending on the supply amount of the liquefied carbon dioxide gas, but is usually a pipe having a large diameter of about 1.5 to 2 times the liquefied carbon dioxide supply pipe 5, for example, the liquefied carbon dioxide supply pipe 5. When the nominal diameter is 20A, a pipe of about 32A is used, the inclination angle is 30 degrees or less with respect to the horizontal plane, preferably about 3 to 10 degrees, the length is about 4000 to 5000 mm, and the liquid level (liquid depth) is What is necessary is just to make it about 300-400 mm. These dimensions and the like are related to each other. For example, if the inclination angle of the inclined tube 3 is increased too much, the flow rate of the liquefied carbon dioxide gas flowing into the inclined tube 3 is increased, and the liquid surface may be waved. Therefore, there are cases where gaseous carbon dioxide is entrained in liquid carbon dioxide and sufficient gas-liquid separation becomes difficult. Conversely, if the inclination angle is too small, the gaseous carbon dioxide in the liquid carbon dioxide will be liquid. In this case, sufficient gas-liquid separation may be difficult because the speed of rising to the surface becomes slow. In any case, considering the flow rate of the liquid carbon dioxide gas and the rising speed of the gaseous carbon dioxide gas, the flow rate of the liquid carbon dioxide gas in the inclined pipe 3 is 0.3 m or less per second, particularly about 30 to 100 mm per second. It is preferable to set the diameter and inclination angle of the pipe.
[0015]
Further, the inflow portion of the carbon dioxide gas in the gas-liquid mixed state in the inclined pipe 3 is liquefied carbon dioxide supply pipe 5 so that the liquefied carbon dioxide gas can smoothly flow into the inclined pipe 3 without foaming as shown in FIG. It is preferable that an inflow pipe 3a having the same diameter as that of the inclined pipe 3 is interposed between the inflow pipe 3a and the inflow pipe 3a. In addition, the installation position of the inflow pipe 3a is that the gas-liquid mixed carbon dioxide gas does not directly flow into the liquid phase portion in the inclined pipe 3, but the liquid carbon dioxide gas flows out from the gaseous carbon dioxide exhaust pipe 6. It is preferable to set it slightly above the middle part of the inclined tube 3 so as not to be present.
[0016]
In addition, when there is a sufficient distance in the horizontal direction from the liquefied carbon dioxide storage tank 4 to the snow horn 2, a part or all of the inclined tube 3 can be arranged linearly. Further, the inclined pipes 3 do not have to have the same diameter over the entire length, and different diameter pipes may be mixed. Furthermore, it is not necessary that all have the same inclination angle, and some can be horizontal or vertical.
[0017]
By performing gas-liquid separation of the liquefied carbon dioxide gas using the inclined pipe 3 as described above, the liquefied carbon dioxide gas (the carbon dioxide gas in a gas-liquid mixed state) flowing into the inclined pipe 3 from the liquefied carbon dioxide supply pipe 5 is Gas-liquid separation is performed while flowing downward along the inclination of the inclined pipe 3, and the separated liquid carbon dioxide gas flows into the liquid carbon dioxide gas stored in the inclined pipe 3 with a relatively gentle flow. The surface is not undulated and the gaseous carbon dioxide is not caught in the liquid carbon dioxide. Even if gaseous carbon dioxide is entrained in the liquid carbon dioxide, the distance from the liquid surface portion to the connecting portion of the liquid carbon dioxide supply pipe 7 can be made sufficiently long. Gaseous carbon dioxide can be reliably separated, and the nozzle 1 is not supplied with gaseous carbon dioxide mixed therein.
[0018]
Further, pilot pipes 8 a and 8 b are connected to the upper and lower parts of the inclined pipe 3, and the lower pressure of the inclined pipe 3 to which the liquid carbon dioxide liquid head accumulated in the inclined pipe 3 is applied, and the gas portion at the upper part of the inclined pipe 3. A differential pressure type liquid level gauge 8 for detecting the liquid level in the inclined pipe 3 from the differential pressure with respect to the pressure is provided, and the automatic valve 10 is controlled to open and close by the detected liquid level, whereby the liquid level in the inclined pipe 3 is predetermined. Therefore, liquid carbon dioxide mixed with gaseous carbon dioxide can be reliably prevented from being supplied to the nozzle 1.
[0019]
When producing dry ice using the above apparatus, first, a gas take-off valve provided in the liquefied carbon dioxide gas storage tank 4 in order to prevent dry ice from being generated in the pipe and blocking the pipe. 4a is opened, and the gaseous carbon dioxide in the storage tank is supplied from the liquefied carbon dioxide supply pipe 5 to each path such as the inclined pipe 3 for gas-liquid separation, the liquid carbon dioxide supply pipe 7, etc., and these are pressurized and cooled. .
[0020]
When the pressure in each passage reaches a predetermined pressure, the gas extraction valve 4a of the liquefied carbon dioxide storage tank 4 is closed and the liquid extraction valve 4b is opened to start supplying the liquefied carbon dioxide gas. The automatic valve 10 is opened to evacuate. As a result, the inclined pipe 3 enters a state in which liquefied carbon dioxide gas (gas-liquid mixed carbon dioxide) flows in while the gaseous carbon dioxide is exhausted, and the liquid carbon gas that has been gas-liquid separated gradually enters the lower part of the inclined pipe 3. It will be stored.
[0021]
When the liquid level in the inclined pipe 3 reaches a predetermined height, the automatic valve 9 is opened, and liquid carbon dioxide that does not contain gaseous carbon dioxide gas is discharged from the lower part of the inclined pipe 3 through the liquid carbon dioxide supply pipe 7. 1 and is ejected into the snow horn 2. The liquid carbon dioxide jetted into the snow horn 2 adiabatically expands to generate dry ice, and the generated dry ice falls from the lower end opening of the snow horn 2.
[0022]
When the detection liquid level of the differential pressure type liquid level gauge 8 reaches a predetermined height, the automatic valve 10 is closed to stop the exhaust, and when the detection liquid level becomes lower than the predetermined height, the automatic valve 10 is opened and the upper portion of the inclined pipe 3 is opened. The gaseous carbon dioxide is exhausted, that is, stored in the inclined pipe 3. By repeating this operation during the dry ice production operation, the liquid carbon dioxide gas can be supplied to the nozzle 1 in a stable state.
[0023]
In this way, by performing gas-liquid separation with the inclined pipe 3, it is possible to supply the liquid carbon dioxide gas, which is sufficiently gas-liquid separated and not mixed with gaseous carbon dioxide gas, to the nozzle 1, so that the dry ice is always in a stable state. Can be manufactured. In addition, the installation space can be reduced by installing the inclined tube 3 in a spiral shape so as to surround the outer periphery of the snow horn 2, and the apparatus can be greatly reduced in size compared with the case where a tank-shaped gas-liquid separator is installed. Can be planned.
[0024]
【Example】
An experiment for producing dry ice was performed using the apparatus having the structure shown in FIG. The size of each part of the apparatus is as follows.
Snow horn: total length 500mm, outer diameter 139.8mm
Liquid carbon dioxide injection nozzle: 4 nozzles at regular intervals on the circumference centered on the top of the head Nozzle hole diameter: 0.1 mm
Supply pressure: 20 kgf / cm ²
Supply amount: 3kg / min
Liquefied carbon dioxide supply pipe: Nominal diameter 20A
Inclined tube for gas-liquid separation: Nominal diameter 32A
Spiral height: 585mm
Inclination angle: 5 degrees with respect to the horizontal plane Carbon dioxide supply pipe: Nominal diameter 10A
As a result, the operation could be continued in a stable state, and good dry ice could be obtained continuously.
[0025]
【The invention's effect】
As described above, according to the present invention, gas-liquid separation can be efficiently performed by the inclined tube having a predetermined inclination angle, and gaseous carbon dioxide gas is mixed into the liquid carbon dioxide gas injected into the snow horn. Therefore, dry ice can be produced in a stable state. Further, by arranging the inclined pipe in a spiral shape, it is possible to reduce the size as compared with an apparatus using a tank-shaped gas-liquid separator.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an embodiment of the dry ice production apparatus of the present invention.
FIG. 2 is a schematic diagram showing a gas-liquid separation state in an inclined pipe.
FIG. 3 is a partial cross-sectional plan view showing an example of a connection state between an inclined pipe and a liquefied carbon dioxide supply pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Nozzle, 2 ... Snow horn, 3 ... Inclined pipe, 4 ... Liquefied carbon dioxide storage tank, 5 ... Liquefied carbon dioxide supply pipe, 6 ... Gaseous carbon dioxide exhaust pipe, 7 ... Liquid carbon dioxide supply pipe, 8 ... Differential pressure type Level gauge, 9, 10 ... Automatic valve, 11 ... Holding pressure valve

Claims (2)

  In a dry ice manufacturing apparatus provided with a cylindrical body having an open lower end and a nozzle for adiabatic expansion by ejecting liquefied carbon dioxide gas into the cylindrical body, an inclined pipe is provided on the outer periphery of the cylindrical body, The inclined pipe is connected to a liquefied carbon dioxide supply pipe for supplying liquefied carbon dioxide gas from a gas supply source, and an outlet for gaseous carbon dioxide separated in the inclined pipe is provided at the upper part of the inclined pipe. An apparatus for producing dry ice, characterized in that a liquid carbon dioxide supply pipe for supplying liquid carbon dioxide separated into gas and liquid to the nozzle is connected to the lower part of the apparatus.   The apparatus for producing dry ice according to claim 1, wherein the inclined pipe has a larger diameter than a liquefied carbon dioxide supply pipe connecting the inclined pipe and a liquefied carbon dioxide supply source.

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