JPH057600B2 - - Google Patents

Description

Detailed Description of the Invention <<Industrial Application Field>> The present invention relates to a device for supplying a fixed amount of liquefied gas to equipment using liquefied gas. It is used as a device to supply

<<Prior Art>> For devices that utilize the low-temperature thermal energy possessed by liquefied gas, it is required to accurately control the temperature and supply amount of the liquefied gas.

Conventionally, such a liquefied gas supply device supplies liquefied carbon dioxide from a liquefied carbon dioxide gas storage tank T, as shown in FIG. A supply path L is led out, the tip of this liquefied carbon dioxide gas supply path L is communicated with an air blowing nozzle N of the blow molding machine via a blowing branch path P, and a flow meter M is interposed in the branch path P. By detecting the supply amount with this flowmeter M, a constant flow rate of liquefied carbon dioxide gas was blown in for a certain period of time.

<<Problem to be solved>> However, in this case, when the remaining amount of liquid in the liquefied gas storage tank T decreases as liquefied carbon dioxide gas is used, the vapor pressure balance in the storage tank T collapses and the liquefied carbon dioxide gas Vaporization is activated and the liquid temperature decreases. For this reason, even if a fixed amount of liquefied carbon dioxide is injected into the molded product for a set amount of time, the temperature of the supplied liquid will fluctuate, causing the latent heat of vaporization and sensible heat of the liquefied carbon dioxide to fluctuate, making the cooling rate inconsistent. . Furthermore, since the vapor pressure within the storage tank decreases and the flow rate of the delivered liquefied gas also decreases, there is also the problem that the supply amount fluctuates even if the liquefied gas is ejected for a certain period of time. Therefore, the liquefied gas supply amount must be set based on a high liquid temperature and a slow flow rate, which not only wastes the thermal energy of the liquefied gas but also increases the mold occupation time. However, there is a problem in that the operating speed of the entire production line is slow and the production efficiency is low.

Furthermore, since the liquefied gas supply system is configured in an open loop, the liquefied gas is vaporized in the supply path due to the intrusion heat acting on the liquefied gas supply system from the outside, and this vaporized gas becomes liquefied gas. This will cause the mixture to pass through the flow meter, resulting in an error in the amount of liquefied gas supplied. This results in a decrease in production efficiency.

<Means for Solving the Problems> The present invention provides a device that can efficiently supply a fixed amount of liquefied gas at constant temperature and pressure. By connecting the supply path and the liquefied gas return path, the liquefied gas flow path is constructed into a closed loop, and a liquid feeding pump is placed in the liquefied gas flow path to circulate the liquefied gas. A cooling device for maintaining the liquid temperature of the liquefied gas at a constant level is disposed in the liquefied gas, and the liquefied gas maintained at a constant temperature is supplied to the liquefied gas using device.

<<Operation>> In the present invention, a cooling device is provided in the liquefied gas supply system, and a liquid feeding pump is arranged in the liquefied gas supply path, so that the liquefied gas at a constant temperature (for example, -30°C) is kept at a constant pressure. Since the liquefied gas is supplied to the equipment in use by time control, even if the liquefied gas is supplied to the equipment in use, the amount of supply is stable and the amount of heat retained is also stable. Furthermore, since the liquefied gas flow path is formed in a closed loop and is configured to circulate the liquefied gas, even if it is gasified in the piping system due to the influence of heat intrusion from the outside, the gas components will be circulated. It rides on the liquid flow and flows into the liquefied gas return path,
No gas enters the equipment used, and a fixed amount of liquefied gas is sent to the equipment used.

<<Example>> Fig. 1 shows a flowchart in the case where liquefied gas is supplied into the interior of a blow-molded synthetic resin product and used as a cooling medium.

This liquefied gas quantitative supply device supplies liquefied carbon dioxide extracted from a liquefied carbon dioxide storage tank 1 into a blow molding machine 2, and uses the heat of vaporization of the liquefied carbon dioxide to cool a resin molded product from inside. The liquefied gas flow path 3 is configured to supply a fixed amount of liquefied carbon dioxide gas, and the liquefied gas flow passage 3 is connected to the liquefied gas supply path 4 led out from the bottom of the liquefied carbon dioxide storage tank 1 and the liquefied gas supply path 4 that communicates with the upper part of the liquefied carbon dioxide storage tank 1. The return path 5 forms a closed loop. A branch pipe 6 branched from the liquefied gas supply path 4 is connected to a nozzle 8 of the blow molding machine 2.
It is connected to the liquefied gas usage section. A liquid feed pump 9 is disposed in the middle of the liquefied gas supply path 4, and the flow rate of the liquefied gas flowing through the liquefied gas supply path 4 is controlled by a flow rate control valve 10 disposed downstream of the liquid feed pump 9. The flow rate is set to be 5 to 15 times the amount of liquefied gas consumed by the blow molding machine 2.

On the other hand, the liquefied gas return path 5 is communicated with the liquefied carbon dioxide storage tank 1 via the heat exchanger 11, and the return liquid flowing through the return path 5 is cooled in the heat exchanger 11, and then the liquefied carbon dioxide It is designed to be released in a shower-like manner in the gas phase at the upper part of the storage tank 1. In this way, when the heat exchanger 5 is interposed in the liquefied carbon dioxide gas return path 11, the cooled return liquid flows into the large capacity liquefied carbon dioxide storage tank 1. In addition to making it easier to control the liquid temperature in the tank 1, since the returning liquid is discharged into the gas phase in a shower-like manner, the gas-liquid equilibrium state in the storage tank 1 is maintained, and the temperature in the storage tank 1 is maintained at a constant temperature. Liquefied carbon dioxide gas at constant pressure is obtained.

As a result, most of the liquefied carbon dioxide extracted from the liquefied carbon dioxide storage tank 1 is circulated through the gas flow path 3. In this case, the temperature of the liquefied gas returned to the liquefied gas storage tank 1 is controlled by the heat exchanger 11 to be equal to the temperature of the liquid extracted from the liquefied gas storage tank 1.

The heat exchanger 11 uses Freon R22 as a refrigerant, cools the return liquid with this refrigerant, condenses the gas components mixed in the return liquid, and transfers it to the liquefied carbon dioxide storage tank 1 in a gas-free state. It is configured to return. The refrigerant that has undergone heat exchange in the heat exchanger 11 is condensed in a refrigerator 12 and is sent into the heat exchanger 11 again.

A branch pipe 6 branched out from the liquefied gas supply path 4
As shown in Figure 2, stainless steel bellows tube 1
The outer surface of the nozzle 3 is covered with a rubber heat insulating layer 14, and the outer surface of the rubber heat insulating layer 14 is covered with a mesh body 15, so that the nozzle 8 can be moved up and down. Further, this branch pipe 6 is formed such that its cross-sectional area becomes smaller as it goes from the outlet base side to the outlet end side. By configuring each branch pipe 6 in this way, even if liquefied carbon dioxide gas is vaporized in the branch pipe 6 and a gas component is generated, the vaporized gas component can escape to the liquefied gas supply path 4 side. No more flowing into the molding machine.

3 and 4 show another embodiment of the present invention, and the one shown in FIG. 3 is a liquefied carbon dioxide gas storage tank 1 and a heat exchanger 11 disposed outside the liquefied gas storage tank 1.
are connected by cooling piping 16 to form a liquefied gas cooling system, and by passing the liquefied carbon dioxide in the liquefied carbon dioxide storage tank 1 through the heat exchanger 11, the temperature of the liquefied gas in the storage tank 1 can be controlled. It is designed to maintain a constant temperature. As a modification of this embodiment, it is conceivable to arrange the heat exchanger 11 within the liquefied gas storage tank 1 and to perform heat exchange directly.

In the device shown in FIG. 4, a heat exchanger 11 is arranged in the liquefied gas supply path 4 on the downstream side of the liquid feeding pump 9,
The liquefied gas sent out from the liquid sending pump 9 is kept at a constant temperature and supplied to the blow molding machine 2.

In each of the above embodiments, a case has been described in which liquefied carbon dioxide gas is supplied as a cooling medium to a resin blow molding machine, but the present invention can be used, for example, to supply a fixed amount of liquefied gas in various types of refrigeration equipment.

In the liquefied gas quantitative supply device having the above configuration, the liquid feeding pump 9 is disposed in the liquefied gas supply path 4, and a cooling device (heat exchanger) is disposed in the liquefied gas supply system. It is possible to supply a fixed amount of liquefied gas at constant temperature and pressure to gas-using equipment, and maintain the retained heat amount constant.

<<Effects>> In the present invention, the liquefied gas flow path led out from the bottom of the liquefied gas storage tank is connected to the top of the liquefied gas storage tank to form a closed loop, and a cooling device is disposed in the liquefied gas supply system. Since the liquid pump is disposed in the liquefied gas supply path between the gas storage tank and the liquefied gas usage device, it is possible to supply a fixed amount of constant temperature and pressure liquefied gas to the liquefied gas usage device. As a result, stable low-temperature thermal energy can be obtained at all times, making it possible to set machining times without energy loss, increasing the work speed before and after equipment using liquefied gas, and It is possible to increase production efficiency by increasing operating efficiency.

Moreover, the structure is such that the liquefied gas flow path is piped in a closed loop, a pump is interposed in the liquefied gas supply path, and a cooling device is installed in the liquefied gas supply system, so it can be used with existing equipment. It can be easily implemented.

[Brief explanation of the drawing]

Fig. 1 is a flowchart when supplying liquefied gas to a blow molding machine, Fig. 2 is a vertical cross-sectional view of a branch pipe, Figs. 3 and 4 are flowcharts of different embodiments, and Fig. 5 is a flowchart of a conventional example. This is a flowchart. 1... Liquefied gas storage tank, 2... Liquefied gas usage device (blow molding machine), 3... Liquefied gas flow path, 4
...Liquefied gas supply path, 5...Liquefied gas return path, 9
... Liquid pump, 11 ... Cooling device (heat exchanger),
16... Cooling piping.

Claims (1)

[Claims] 1. The liquefied gas supply path 4 led out from the bottom of the liquefied gas storage tank 1 is connected to the liquefied gas usage device 2, and the liquefied gas usage device 2 and the upper part of the liquefied gas storage tank 1 are liquefied. The liquefied gas flow path 3 is configured as a closed loop by communicating with the gas return path 5, and the liquid feeding pump 9 is disposed in the liquefied gas supply path 3, and the liquefied gas is supplied to the liquefied gas supply system including the liquefied gas storage tank 1. A quantitative supply device for liquefied gas, characterized in that it is equipped with a cooling device 11 that maintains a constant liquid temperature. 2. The liquefied gas quantitative supply device according to claim 1, wherein the cooling device 11 is disposed in the liquefied gas flow path 3 downstream of the liquid feeding pump 9. 3. The liquefied gas quantitative supply device according to claim 2, wherein the cooling device 11 is disposed in the liquefied gas return path 5. 4. The liquefied gas quantitative supply device according to claim 2, wherein the cooling device 11 is disposed in the liquefied gas supply path 4. 5 The liquefied gas in the liquefied gas storage tank 1 is cooled by the cooling device 1.
Claim 1 configured to cool in 1
The liquefied gas metering supply device described in section. 6. The liquefied gas quantitative supply device according to claim 5, wherein the heat exchange section of the cooling device 11 is disposed within the liquefied gas storage tank 1. 7 Connect the heat exchange part of the cooling device 11 to the liquefied gas storage tank 1
The liquefied gas quantitative supply device according to claim 5, which is arranged outside of the storage tank 1 and the heat exchange section through a cooling pipe 16. 8. Claim 1, wherein the return liquid is spouted in a shower shape from the terminal end of the liquefied gas return path 5 communicating with the upper part of the liquefied gas storage tank 1.
The liquefied gas quantitative supply device described in any one of Items 7 to 7.