JP5512339B2 - Remodeling existing food freezing equipment - Google Patents

Description

The present invention relates to a method for retrofitting a refrigeration cycle of fluorocarbon refrigerant use food freeze the row of cormorants already設食goods refrigeration equipment as a heat source.

  Generally, chlorofluorocarbon refrigerants are generally called CFC (chlorofluorocarbon), which is a specific chlorofluorocarbon from the molecular structure, and HCFC (hydrochlorofluorocarbon), such as R-22, and chlorofluorocarbon, which are developed for its use. It is classified as HFC (hydrofluorocarbon). CFC refrigerants are chemically stable and difficult to decompose, and are decomposed for the first time in the stratosphere. The chlorine generated there destroys the ozone layer and was completely abolished at the end of 1995.

On the other hand, since HCFC refrigerant is not as chemically stable as CFC refrigerant, the amount reaching the stratosphere is small and the influence on the ozone layer is about 1/20 of that of CFC refrigerant. Production and consumption are regulated up to.
Further, since the HFC refrigerant does not contain chlorine in the molecule, it is a refrigerant that does not destroy the ozone layer, and is a refrigerant that is used instead of CFC or HCFC. However, as with HCFC refrigerant, because of its greenhouse number 100-10000 times more than in the CO _2, regulations on even these fluorocarbon refrigerant taken up as one of the causes of global warming use is enhanced It's getting on.

Here, with reference to FIGS. 6 and 7 showing a conventional example, a food freezing facility for freezing food using a chlorofluorocarbon refrigerant will be described.
FIG. 6 is a configuration example of a food refrigeration facility provided with an evaporative condenser 52. This food refrigeration equipment includes a refrigeration cycle using a fluorocarbon refrigerant. The chlorofluorocarbon refrigerant compressed by the refrigerator (compressor) 51 is condensed and liquefied by the evaporative condenser 52, and then supplied to the expansion valve 54 via the chlorofluorocarbon high-pressure receiver 53 to be expanded. The liquefied chlorofluorocarbon refrigerant is cooled by the air cooler 55 by the latent heat of vaporization and then returned to the refrigerator 51. And the freezing space of the food freezer compartment 56 is cooled by the cooling air cooled by the air cooler 55, and for example, the food 58 conveyed on the spiral conveyor 57 is frozen as shown in the figure. .
FIG. 7 is a configuration example of a food refrigeration facility provided with a water-cooled condenser 62. This food refrigeration equipment is different from the refrigeration equipment shown in FIG. 6 in the configuration of the condenser. The cooling water cooled by the cooling tower 61 is sent to the water-cooled condenser 62 by a pump, and the water-cooled condenser 62 It is configured to condense the fluorocarbon refrigerant.

  Conventionally, many refrigeration facilities using the above-mentioned chlorofluorocarbon refrigerants have been widely used. However, in consideration of future refrigerant problems, newly produced refrigeration facilities are natural refrigerants that are friendly to the global environment. Is being promoted to use. In particular, from the viewpoint of emphasizing correspondence to general consumers, in the field of the food industry, it is desired to use a natural refrigerant in a refrigeration facility for freezing food or the like. However, the actual situation is that the conversion of existing refrigeration equipment using chlorofluorocarbon refrigerants to use natural refrigerants is not progressing because it takes time and money for remodeling work.

  Therefore, Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-157481) discloses a cooling facility for cooling an object to be cooled such as food or drinking water, and is a brine using an existing R-22 or other Freon refrigerant. A method of remodeling a natural refrigerant cooling facility that can reduce the brine circulation amount of the cooling facility and reduce the pumping power of the natural refrigerant and brine is disclosed. This is because the refrigeration circuit using ammonia refrigerant and the refrigeration circuit using carbon dioxide are connected via a cascade condenser, and the carbon dioxide refrigeration circuit is arranged on the brine circulation line side for cooling the object to be cooled. The refrigeration circuit is switched to the carbon dioxide refrigeration circuit.

JP 2008-157481 A

As described above, in recent years, in refrigeration equipment using chlorofluorocarbon refrigerants, regulations are being advanced due to the large impact on the global environment, but the use of natural refrigerants in refrigeration equipment using existing chlorofluorocarbon refrigerants has been progressing. The conversion was difficult and costly, and it was difficult to completely replace the equipment.
In the food field, the air cooler placed in the food freezer compartment is in direct contact with the food via the air circulating in the food freezer compartment, so that cleaning and maintenance are performed as hygiene management for daily production machinery. Yes. However, since the fins and piping of the air cooler may be damaged or the durability may be deteriorated due to the cleaning, there is a possibility that foreign matters are mixed into the food and chlorofluorocarbon refrigerant leaks out.

  Therefore, by adopting the configuration described in Patent Document 1, it is not necessary to use a chlorofluorocarbon-based refrigerant, which is effective from the viewpoint of global environmental conservation. Switching to a refrigeration circuit using natural refrigerant and a carbon dioxide refrigeration circuit is a major remodeling, and because it cannot use the CFC-based refrigerant used in existing facilities, the cost increases. there were.

Therefore, there is a demand for a refrigeration facility that can effectively continue to use the chlorofluorocarbon refrigerant without causing problems such as leakage of the chlorofluorocarbon refrigerant, is inexpensive and harmless to the global environment.
The present invention is the conventional view of the art problems, existing food freezing equipment, remodeling significant remodeling without global environment harmless refrigeration equipment can Ru already設食products refrigeration equipment to switch to using a fluorocarbon refrigerant Provide a method.

In order to solve the above-described problems, a Freon-based refrigeration circuit that constitutes a refrigeration cycle using a Freon-based refrigerant is disposed in a machine room or an outdoor or rooftop (hereinafter abbreviated as a machine room) adjacent to the machine room. with which, is disposed an air cooler to freeze food using the flon refrigerant in food freezing compartment, circulation line of fluorocarbon refrigerant is provided between the air cooler and the flon refrigerant circuit In remodeling existing food freezing equipment,
The CFC-based refrigeration circuit disposed in the machine room or the like cools and condenses high-temperature and high-pressure CFC-based refrigerant gas compressed by a compressor with a condenser, and passes the liquefied CFC-based refrigerant liquid with a liquid cooler. A CFC refrigeration circuit for producing a low-pressure chlorofluorocarbon refrigerant liquid by cooling with an expansion valve after cooling, and further adding a CO ₂ liquefaction unit to the machine room or the like without removing the CFC refrigeration circuit. Set up
The additionally installed CO ₂ liquefaction unit includes a surge drum to which a low-pressure fluorocarbon refrigerant manufactured in the fluorocarbon refrigeration circuit is supplied, and a cascade capacitor through which the fluorocarbon refrigerant from the surge drum flows. And a cascade structure in which a CO ₂ receiver that stores the CO ₂ refrigerant cooled and liquefied by the low-pressure chlorofluorocarbon refrigerant in the cascade condenser is disposed in order from above , and cascaded with the surge drum between the capacitor to form a circulation line which naturally circulates the fluorocarbon refrigerant and CO ₂ liquefaction unit additionally forming a circulation line for natural circulation of CO ₂ refrigerant between the cascade condenser and CO ₂ receiver Setting step,
A switching step of switching the connection between the air cooler disposed in the food freezer compartment and the CO ₂ receiver in the machine room or the like from the fluorocarbon refrigerant circulation line to the CO ₂ circulation line, and the air cooler Is modified into an air cooler that freezes food using CO ₂ refrigerant .

According to the present invention, by constructing a CO ₂ liquefaction unit from a surge drum, a cascade capacitor, and a CO ₂ receiver, the existing equipment can be greatly increased by adding this CO ₂ liquefaction unit to an existing food freezing facility. It is possible to easily switch to a refrigeration facility that is harmless to the global environment without modification.
In addition, the CO ₂ liquefaction unit has a saddle type structure in which the height position is lowered in the order of the surge drum, cascade capacitor, and CO ₂ receiver, so that the CFC refrigerant is passed between the surge drum and the cascade capacitor. Natural circulation can be achieved, and CO ₂ refrigerant can be naturally circulated between the cascade condenser and the CO ₂ liquid receiver, so that the installation cost and power cost of the pump can be reduced. Furthermore, the installation area can be reduced by making the CO ₂ liquefaction unit vertical, and it is possible to easily add a CO ₂ liquefaction unit to the machine room side without significantly expanding existing refrigeration equipment. It becomes.
The chlorofluorocarbon refrigerant includes CFC (chlorofull carbon), HCFC (hydrochlorofluorocarbon), and HFC (hydrofluorocarbon).

Also, the piping structure of at least one of the Freon refrigerant pipe connecting the surge drum and the cascade condenser and the CO ₂ refrigerant pipe connecting the cascade condenser and the CO ₂ receiver. In the above, it is preferable that the pipe through which the liquid mainly flows is connected to the lower part of the apparatus on the pipe inlet side, and the pipe through which the gas mainly flows is connected to the upper part of the apparatus.
As described above, in the piping structure of each device (surge drum, cascade condenser, CO ₂ receiver) of the CO ₂ liquefaction unit, the piping through which liquid mainly flows is connected to the lower portion of the device at the piping inlet side. Thus, the liquid refrigerant can be circulated without using a pump or the like. In addition, by connecting the pipe inlet side to the upper part of the device, the pipe through which gas mainly flows can circulate only the gas accumulated in the upper part of the device to other devices.

Furthermore, it is preferable that the cascade condenser is a plate shell type heat exchanger.
Since the plate shell heat exchanger is a compact construction, the machine room, can be disposed in the vicinity of the flon refrigerant circuit of the existing, -40 viscosity of CO ₂ liquid ℃ is also very small for electrical It is only necessary to add a CO ₂ liquid pump with low power consumption, and installation is easy because it does not require any change in electrical equipment.

In this food refrigeration equipment, a CO ₂ liquefaction unit is provided in the vicinity of a chlorofluorocarbon refrigeration circuit such as a machine room, and the air cooler is configured to correspond to the pressure of the CO ₂ refrigerant. The CO ₂ liquefaction unit, the air cooler, A CO ₂ circulation line is configured between the _two .
The CO ₂ liquefaction unit includes a cascade condenser which constitutes the evaporator fluorocarbon refrigeration circuit, a circulation line for natural circulation of CO ₂ refrigerant between the cascade condenser and CO ₂ CO ₂ receiver in the liquefaction unit Form between. The CO ₂ refrigerant is liquefied by the latent heat of evaporation of the chlorofluorocarbon refrigerant by the cascade condenser, and the liquefied CO ₂ refrigerant is sent to the air cooler disposed in the food freezer compartment through the CO ₂ receiver through the CO ₂ circulation line. The CO ₂ refrigerant partially evaporates and takes away latent heat of evaporation from the surroundings, thereby cooling the atmosphere in the food freezer compartment. The partially vaporized CO ₂ refrigerant returns to the CO ₂ receiver, and is cooled and liquefied by the chlorofluorocarbon refrigerant in the cascade condenser.
By adopting such a configuration, since the chlorofluorocarbon refrigerant is sealed in the circulation line between the chlorofluorocarbon refrigeration circuit and the CO ₂ liquefaction unit in the vicinity thereof, the filling amount of the chlorofluorocarbon refrigerant is small, and the chlorofluorocarbon refrigerant is There is almost no risk of leakage to the outside, and it is possible to provide a food freezing facility that is harmless to the global environment.

Furthermore, in the remodeling method of the existing food refrigeration equipment according to the present invention, the chlorofluorocarbon refrigeration circuit arranged in the machine room or the like cools the high-temperature and high-pressure chlorofluorocarbon refrigerant gas compressed by the compressor with a condenser. A CFC-based refrigeration circuit for producing a low-pressure CFC-based refrigerant liquid by subcooling the condensed and liquefied CFC-based refrigerant liquid with a liquid cooler, and then expanding the expansion valve to remove the CFC-based refrigeration circuit. Without further installing a CO ₂ liquefaction unit in the machine room or the like ,
The additionally installed CO ₂ liquefaction unit includes a surge drum to which a low-pressure fluorocarbon refrigerant manufactured in the fluorocarbon refrigeration circuit is supplied, and a cascade capacitor through which the fluorocarbon refrigerant from the surge drum flows. And a cascade structure in which a CO ₂ receiver that stores the CO ₂ refrigerant cooled and liquefied by the low-pressure chlorofluorocarbon refrigerant in the cascade condenser is disposed in order from above , and cascaded with the surge drum between the capacitor to form a circulation line which naturally circulates the fluorocarbon refrigerant and CO ₂ liquefaction unit additionally forming a circulation line for natural circulation of CO ₂ refrigerant between the cascade condenser and CO ₂ receiver Setting step,
A switching step of switching the connection between the air cooler disposed in the food freezer compartment and the CO ₂ receiver in the machine room or the like from the fluorocarbon refrigerant circulation line to the CO ₂ circulation line, and the air cooler Is an air cooler that freezes food using a CO ₂ refrigerant. Specifically, the CFC refrigerant provided between the surge drum and the cascade condenser is naturally circulated. As described in paragraph (0035) below, the circulation line to be supplied includes a supply line 42 for supplying the chlorofluorocarbon refrigerant liquid in the surge drum 31 to the cascade condenser 35 and the chlorofluorocarbon refrigerant gas in the cascade condenser 35 to the surge drum 31. return a line 43, also circulation line for natural circulation of CO ₂ refrigerant between the cascade condenser and CO ₂ receiver after returning "A supply line 45 for supplying the CO ₂ refrigerant gas in the cascade condenser 35, return line 46 for returning CO ₂ refrigerant liquid into CO ₂ receiver 37 'as described in paragraph (0036) consisting of a.
The CO ₂ circulation line for connecting the air cooler disposed in the food freezer and the CO ₂ receiver in the machine room or the like is “ CO ₂ refrigerant from the CO ₂ receiver 37 to the air cooler _2. A CO ₂ circulation line 47a for supplying the liquid, and a CO ₂ circulation line 47b for returning the gas-liquid mixture of the CO ₂ refrigerant gas and the liquid from the air cooler 2 to the CO ₂ receiver 37 .

Furthermore , according to the present invention, this refrigeration circuit is used as it is as a heat source for the CO ₂ circulation line without removing the chlorofluorocarbon refrigeration circuit, and the refrigeration cycle through which the chlorofluorocarbon refrigerant circulates is minimized. For this reason, even if the regulations on chlorofluorocarbon refrigerants such as R-22 are further strengthened, it is possible to provide refrigeration equipment that is harmless to the global environment without any problems.
Further, as described above, since the air cooler disposed in the food freezer compartment is in direct contact with the food via the air circulating in the food freezer compartment, cleaning for cleaning is performed as hygiene management for daily production machines. Therefore, the air cooler arranged in the food freezer is periodically updated. On the other hand, the refrigeration apparatus that constitutes the refrigeration cycle that is the heat source of the food freezer can be used for a long time without failure by periodically replacing the bearings based on the accumulated operating time, It will not be updated unless there is a change in production scale, such as a production line update. By adopting the remodeling method of the present invention in accordance with the renewal time of the air cooler that will be renewed in a short period of time compared to refrigeration equipment, facilities that are harmless to the global environment without significantly remodeling existing food refrigeration equipment Can be modified.

As described above, according to the present invention, a CO ₂ liquefaction unit is configured from a surge drum, a cascade capacitor, and a CO ₂ receiver, and this CO ₂ liquefaction unit is additionally installed in an existing food freezing facility. Thus, it is possible to easily switch to a refrigeration facility that is harmless to the global environment without significantly modifying existing facilities.
In addition, the CO ₂ liquefaction unit has a saddle type structure in which the height position is lowered in the order of the surge drum, cascade capacitor, and CO ₂ receiver, so that the CFC refrigerant is passed between the surge drum and the cascade capacitor. Natural circulation can be achieved, and CO ₂ refrigerant can be naturally circulated between the cascade condenser and the CO ₂ liquid receiver, so that the installation cost and power cost of the pump can be reduced. Further, the installation area can be reduced by making the CO ₂ liquefaction unit into a vertical shape, and the CO ₂ liquefaction unit can be easily added to the machine room side without greatly expanding the existing refrigeration equipment .

It is a basic lineblock diagram of the food freezing equipment concerning the present invention. It is a block diagram showing a CO ₂ liquefaction unit. Is a diagram showing a CO ₂ liquefaction unit, (A) is a side view, (B) is a front view. 1 is an overall configuration diagram of a food freezing facility according to a first embodiment of the present invention. It is a whole block diagram of the food freezing equipment which concerns on 2nd Embodiment of this invention. It is a whole food refrigeration equipment block diagram provided with the conventional evaporation type condenser. It is a whole food refrigeration equipment block diagram provided with the conventional air cooling type condenser.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
FIG. 1 is a basic configuration diagram of a food freezing facility according to the present invention. This food freezing facility is a freezing facility for freezing food (including beverages). Food includes cooked and uncooked foods.
The food freezing facility includes a food freezing room 1 that freezes food and a machine room 10 that generates cold for cooling the food freezing room 1.

The food freezer 1 has an air cooler 2 and a spiral conveyor 3.
The air cooler 2 cools the freezing space of the food freezer compartment 1 with CO ₂ refrigerant circulated from a CO ₂ liquefaction unit described later.
The spiral conveyor 3 is a means for conveying food. Note that the conveying means is not limited to this.
In the food freezer compartment 1 having the above-described configuration, the food conveyed by the spiral conveyor 3 is frozen by the cooling air blown from the air cooler 2.

The machine room 10 includes a Freon refrigeration circuit 20 constituting a refrigeration cycle using a chlorofluorocarbon refrigerant, and a CO ₂ liquefaction unit 30 provided between the Freon refrigeration circuit 20 and the air cooler 2 of the food freezer compartment 1. It has. In the present embodiment, as an example, a configuration in which devices other than the condenser 22, the evaporative condenser 25, and the cooling tower 27 are arranged in the machine room 10 is shown, but the installation location of each device is limited to this. The devices including the CO ₂ liquefaction unit 30 and the chlorofluorocarbon refrigeration circuit 20 can be installed on the machine room 10 or outdoors or on the roof adjacent to the machine room 10.

The chlorofluorocarbon refrigeration circuit 20 includes a refrigerator (compressor) 21, a condenser 22, a chlorofluorocarbon high-pressure receiver 23, and a liquid cooler 24.
The refrigerator 21 is a means for compressing a chlorofluorocarbon refrigerant and may be composed of multiple stages.
The condenser 22 condenses and liquefies the fluorocarbon refrigerant gas compressed by the refrigerator 21. The condenser 22 may be any of a water cooling type, an air cooling type, and an evaporation type.
The CFC-based high-pressure receiver 23 stores CFC-based refrigerant liquid, and mainly adjusts the change in the refrigerant amount due to load fluctuations.
The liquid cooler 24 is means for supercooling the chlorofluorocarbon refrigerant liquid and is selectively installed as necessary.
The chlorofluorocarbon refrigerant includes CFC (chlorofull carbon), HCFC (hydrochlorofluorocarbon), and HFC (hydrofluorocarbon).

The CO ₂ liquefaction unit 30 includes a surge drum 31, an oil return device 32, an expansion valve 33, a cascade capacitor (CO ₂ liquefier) 35, a CO ₂ receiver 37, and a CO ₂ liquid circulation pump 38. Have
The surge drum 31 mixes the chlorofluorocarbon refrigerant liquid supplied from the liquid cooler 24 via the expansion valve 33 with the chlorofluorocarbon refrigerant gas returned from the cascade capacitor 35, and converts the gas-liquid mixture into a gas. The chlorofluorocarbon refrigerant gas is returned to the refrigerator 21 and the chlorofluorocarbon refrigerant liquid is sent to the cascade condenser 35.
The oil return unit 32 returns the refrigeration oil accumulated in the surge drum 31 to the refrigeration unit 21.
The expansion valve 33 expands the high-pressure chlorofluorocarbon refrigerant liquid from the liquid cooler 24 and supplies the low-pressure chlorofluorocarbon refrigerant liquid to the surge drum 31. The expansion valve 33 may be a liquid level control valve.

The cascade condenser 35 cools and liquefies the CO ₂ refrigerant with a fluorocarbon refrigerant. The cascade condenser 35 is preferably a plate shell type heat exchanger. Since the plate shell type heat exchanger has a compact configuration, it can be installed in the machine room 10 in the vicinity of the existing chlorofluorocarbon refrigeration circuit 20, and the viscosity of the CO ₂ liquid at −40 ° C. is very small. In addition, it is only necessary to add a CO ₂ liquid pump with low power consumption, and the installation is easy because it does not require any change in electrical equipment.
The CO ₂ liquid receiver 37 stores a CO ₂ refrigerant liquid and adjusts a change in the refrigerant amount mainly due to load fluctuations.
The CO ₂ liquid circulation pump 38 circulates the CO ₂ refrigerant liquid through the air cooler 2.

A circulation line for naturally circulating a chlorofluorocarbon refrigerant is formed between the surge drum 31 and the cascade condenser 35, and a CO ₂ refrigerant is naturally placed between the cascade condenser 35 and the CO ₂ receiver 37. A circulation line for circulation is formed.

In the food refrigeration facility having the above-described configuration, in the machine room 10, the chlorofluorocarbon refrigerant gas is compressed by the compressor 21 of the chlorofluorocarbon refrigeration circuit 20, and the high-temperature and high-pressure chlorofluorocarbon refrigerant gas is cooled and condensed by the condenser 22. The liquefied chlorofluorocarbon refrigerant is stored in the chlorofluorocarbon high-pressure receiver 23, supercooled by the liquid cooler 24, and then expanded by the expansion valve 33, and the low-pressure chlorofluorocarbon refrigerant is the surge drum of the CO ₂ liquefaction unit 30. 31.
In the surge drum 31, the gas-liquid mixture of the chlorofluorocarbon refrigerant is separated into the chlorofluorocarbon refrigerant gas and the chlorofluorocarbon refrigerant liquid, and the chlorofluorocarbon liquid is sent to the cascade condenser 35. In the cascade condenser 35, the CO ₂ refrigerant gas is liquefied by the latent heat of vaporization of the chlorofluorocarbon refrigerant liquid, and the CO ₂ refrigerant liquid is sent to the air cooler 2 of the food freezer compartment 1 by the CO ₂ liquid circulation pump 38. In the air cooler 2, a part of the CO ₂ refrigerant liquid evaporates and takes away latent heat of evaporation from the surrounding refrigeration space to cool the refrigeration space, and the food conveyed on the spiral conveyor 3 is frozen.

The CO ₂ refrigerant that has passed through the air cooler 2 is returned to the CO ₂ receiver 37 as a gas-liquid mixture of liquid and gas.
On the other hand, the fluorocarbon refrigerant that has passed through the cascade condenser 35 is returned to the surge drum 31 as a gas-liquid mixture of liquid and gas. Then, the fluorocarbon refrigerant gas separated by the surge drum 31 is returned to the refrigerator 21.

By adopting such a configuration, since the chlorofluorocarbon refrigerant is sealed in the circulation line between the chlorofluorocarbon refrigeration circuit 20 and the CO ₂ liquefaction unit in the vicinity thereof, the filling amount of the chlorofluorocarbon refrigerant can be small, and the chlorofluorocarbon refrigerant can be used. There is almost no risk of leakage to the outside, and it is possible to provide a food freezing facility that is harmless to the global environment.

Referring to FIGS. 2 and 3, specifically explained preferred example of a CO ₂ liquefaction unit according to the present invention. Figure 2 is a block diagram schematically showing a CO ₂ liquefaction unit, FIG 3 is a diagram showing a CO ₂ liquefaction unit, (A) is a side view, (B) is a front view.

As shown in FIGS. 2 and 3, the CO ₂ liquefaction unit 30 has a saddle type device configuration in which a surge drum 31, a cascade capacitor 35, and a CO ₂ liquid receiver 37 are arranged in the vertical direction. Specifically, each of the surge drum 31, the cascade capacitor 35, and the CO ₂ receiver 37 is formed in a horizontal cylindrical shape, and is arranged from above in this order. In the CO ₂ liquefaction unit 30 shown in FIG. 3, the surge drum 31 and the cascade capacitor 35 are shifted from the vertical direction due to the structure of the piping. As described above, the positional relationship among the surge drum 31, the cascade capacitor 35, and the CO ₂ receiver 37 may be arranged so as to be shifted from each other as long as the height position is as described above. However, it may be arranged on a straight line in the vertical direction.

As described above, by forming the CO ₂ liquefaction unit 30 from the surge drum 31, the cascade capacitor 35, and the CO ₂ receiver 37, the CO ₂ liquefaction unit 30 can be added to the existing food freezing facility. It is possible to easily switch to a refrigeration facility that is harmless to the global environment without significantly remodeling existing facilities.
Further, the CO ₂ liquefaction unit 30 has a saddle type structure in which the height position is lowered in the order of the surge drum 31, the cascade capacitor 35, and the CO ₂ liquid receiver 37, so that the surge drum 31 and the cascade capacitor 35 are arranged. Fluorocarbon refrigerant can be naturally circulated between them, and CO ₂ refrigerant can be circulated naturally between the cascade condenser 35 and the CO ₂ liquid receiver 37, thereby reducing the installation cost and power cost of the pump. Become. Furthermore, the installation area can be reduced by making the CO ₂ liquefaction unit 30 into a vertical shape, and the CO ₂ liquefaction unit 30 can be easily added to the machine room side without greatly expanding the existing refrigeration equipment. Is possible.

Further, the CO ₂ refrigerant that connects the surge drum 31 and pipe fluorocarbon refrigerant which connects a cascade condenser 35 (line), and the cascade condenser 35 and CO ₂ receiver 37 piping (lines) In the structure, the pipe through which liquid mainly flows is connected to the lower part of the above equipment (surge drum 31, cascade capacitor 35, CO ₂ receiver 37), and the pipe through which gas mainly flows is pipe inlet. Is preferably connected to the top of the device.

Specifically, the following configuration is preferable.
A supply line 41 to which a chlorofluorocarbon refrigerant liquid from the liquid cooler 24 (see FIG. 1) is supplied is connected to the lower portion of the surge drum 31. The supply line 41 is provided with an expansion valve 33.
Further, a return line 44 for returning the chlorofluorocarbon refrigerant gas to the refrigerator 21 is connected to the upper portion of the surge drum 31.
Further, a supply line 42 for supplying a chlorofluorocarbon refrigerant liquid to the cascade capacitor 35 is connected to the lower portion of the surge drum 31, and this supply line 42 is connected to one end of the cascade capacitor 35 in the horizontal direction.
A return line 43 for returning the chlorofluorocarbon refrigerant gas to the surge drum 31 is connected to upper portions of both ends of the cascade capacitor 35 in the horizontal direction. The return lines 43 are connected to both ends of the surge drum 31 in the horizontal direction.

A supply line 45 that supplies CO ₂ refrigerant gas to the cascade condenser 35 is connected to the upper part of the CO ₂ receiver 37, and the supply line 45 is connected to the upper part of the cascade condenser 35.
A return line 46 for returning the CO ₂ refrigerant liquid to the CO ₂ receiver 37 is connected to the lower part of the cascade capacitor 35, and this return line 46 is connected to the upper part of the CO ₂ receiver 37. .
Further, the lower portion of the CO ₂ receiver 37, the upper portion together with CO ₂ circulation line 47a for supplying the CO ₂ refrigerant liquid is connected to an air cooler 2 (see FIG. 1), CO ₂ receiver 37 A CO ₂ circulation line 47b for returning a gas-liquid mixture of the gas and liquid of the CO ₂ refrigerant from the air cooler 2 is connected.

As described above, in the piping structure of each device of the CO ₂ liquefaction unit 30, the piping through which the liquid mainly flows is a liquid refrigerant without using a pump or the like by connecting the piping inlet side to the lower portion of the device. Can be circulated. In addition, by connecting the pipe inlet side to the upper part of the device, the pipe through which gas mainly flows can circulate only the gas accumulated in the upper part of the device to other devices.

Next, specific embodiments of the present invention will be described below. 1st Embodiment is related with the food refrigeration equipment provided with the evaporative condenser, and 2nd Embodiment is related with the food refrigeration equipment provided with the air-cooled condenser.
In the following embodiments, detailed description of the same configuration as the device configuration shown in FIGS. 1 to 3 is omitted. 4 and 5 are the same as those in FIGS. 1 to 3.

(First embodiment)
FIG. 4 is an overall configuration diagram of the food freezing facility according to the first embodiment of the present invention.
The food refrigeration equipment includes an evaporative condenser (Evaporative Condenser) 25. The evaporative condenser 25 causes a fluorocarbon refrigerant to flow through the pipe, sends air between the pipes while spraying water from above, evaporates part of the sprayed water, and takes away the latent heat of vaporization. A known device for cooling the fluorocarbon refrigerant is used.

The high-temperature and high-pressure chlorofluorocarbon refrigerant gas compressed by the refrigerator 21 is sent to the evaporative condenser 25 through the line 48, is condensed and liquefied by the evaporative condenser 25, and then passes through the line 49. It is sent to the high pressure receiver 23. The chlorofluorocarbon refrigerant sent from the chlorofluorocarbon high-pressure receiver 23 is expanded by the expansion valve 33 through the supply line 41 and supplied to the surge drum 31 as a low-pressure chlorofluorocarbon refrigerant.
In the surge drum 31, the chlorofluorocarbon refrigerant liquid is supplied to the cascade condenser 35 through the supply line 42, and the chlorofluorocarbon refrigerant gas used for cooling the CO ₂ refrigerant in the cascade condenser 35 passes through the return line 43. Return to 31. The chlorofluorocarbon refrigerant gas in the surge drum 31 is returned to the refrigerator 21 through the return line 44.

On the other hand, the CO ₂ refrigerant gas-liquid mixture in the CO ₂ receiver 37 is supplied to the cascade capacitor 35 through the supply line 45. The CO ₂ refrigerant cooled by the chlorofluorocarbon refrigerant liquid in the cascade condenser 35 is returned to the CO ₂ liquid receiver 37 through the return line 46. CO ₂ refrigerant liquid CO ₂ liquid receiver 37 passes through the CO ₂ circulation line 47a is supplied to the air cooler 2. In the air cooler 2, the cooling air is cooled by the latent heat of vaporization of the CO ₂ refrigerant, and the cooling air is blown into the freezing space of the food freezing chamber 1. In the food freezer compartment 1, the food conveyed on the spiral conveyor 3 is frozen by this cooling air. CO ₂ refrigerant passing through the air cooler 2 is returned to the CO ₂ receiver 37 through the CO ₂ circulation line 47b in a state where liquid containing the gas.
Thus, according to 1st Embodiment, since it is set as the structure which condenses a CFC-type refrigerant | coolant with the evaporative condenser 25, it can maintain the condensation efficiency of a refrigerant | coolant highly and can reduce the amount of cooling water used for condensation. Is possible.

(Second Embodiment)
FIG. 5 is an overall configuration diagram of the food freezing facility according to the first embodiment of the present invention.
This refrigeration facility includes a water-cooled condenser 26. The water-cooled condenser 26 uses a known device that circulates the water cooled by the cooling tower 27 by the cooling water pump 28 and cools and condenses the chlorofluorocarbon refrigerant in the water-cooled condenser 26 with the cooling water.
The other configuration of the second embodiment is the same as that of the first embodiment described above, and thus the description thereof is omitted.
Thus, according to 2nd Embodiment, since it is set as the structure which condenses a CFC-type refrigerant | coolant with the water-cooling type | mold condenser 26, installation cost is low, and since a pump etc. are unnecessary, power cost can be reduced.

The food refrigeration equipment according to the embodiment of the present invention described above may be manufactured by modifying the conventional refrigeration equipment shown in FIG. 6 or FIG. This modification method is described below.
The existing refrigeration system has a refrigeration circuit that forms a refrigeration cycle using chlorofluorocarbon refrigerant in the machine room, and an air cooler that freezes food using chlorofluorocarbon refrigerant in the food freezer compartment. And a configuration in which a chlorofluorocarbon circulation line is provided between the chlorofluorocarbon refrigeration circuit and the air cooler.

First, as shown in FIG. 2 and FIG. 3, as a first step, a CFC-based refrigerant that is inserted in a CFC-type refrigeration circuit 20 and expanded after being condensed and liquefied in the refrigeration circuit 20 is supplied to the machine room 10 side. Surge tank 31, a cascade condenser 35 through which the chlorofluorocarbon refrigerant from the surge tank 31 flows, and a CO ₂ receiver 37 that stores the liquefied CO ₂ refrigerant cooled by the chlorofluorocarbon refrigerant in the cascade condenser 35. And a CO ₂ liquefaction unit having a vertical structure in which are arranged in order from above. These are connected by a supply line 41 so that the chlorofluorocarbon refrigerant from the chlorofluorocarbon high-pressure receiver 23 is supplied to the surge drum 31, and an expansion valve 33 is disposed on the supply line 41. . Further, these are connected by a return line 44 so that the chlorofluorocarbon refrigerant gas from the surge drum 31 returns to the refrigerator 21.

Next, as a second step, in the existing refrigeration facility, a CFC refrigerant circulation line for a CFC refrigerant returning from the CFC high pressure receiver to the refrigerator through the air cooler is connected to the CO ₂ receiver 37 and the air cooling. The CO ₂ circulation lines 47a and 47b connected to the vessel 2 are switched. A CO ₂ liquid circulation pump is provided on the CO ₂ circulation line 47a.
These steps complete the remodeling work.

According to this remodeling method of the food refrigeration equipment, the refrigeration cycle in which the chlorofluorocarbon refrigerant circulates is used without removing the chlorofluorocarbon refrigeration circuit 20 and using the refrigeration circuit as a heat source for the CO ₂ circulation lines 47a and 47b. Therefore, it is possible to provide refrigeration equipment that is harmless to the global environment without any problem even if the regulation of chlorofluorocarbon refrigerants such as R-22 is further strengthened.
In addition, by adopting the above-mentioned remodeling method according to the renewal time of the air cooler 2 arranged in the food freezer compartment 1, it is possible to make the existing food freezing equipment harmless to the global environment without significantly remodeling. Can be modified.

1 food freezer compartment 2 air cooler 3 spiral conveyor 10 machine room 20 Freon refrigeration circuit 21 the refrigerator 22 condenser 23 flon high pressure liquid receiver 24 liquid cooler 30 CO ₂ liquefaction unit 31 surge drum 35 the cascade condenser 37 CO ₂ Receiver 38 CO ₂ liquid circulation pump

Claims (3)

A freon-based refrigeration circuit constituting a refrigeration cycle using a freon-based refrigerant is disposed on a machine room or on the outdoor or rooftop (hereinafter abbreviated as a machine room) adjacent to the machine room, and the food freezer air cooler to freeze food using flon refrigerant is disposed in the existing method of modifying food freezing equipment circulation line of fluorocarbon refrigerant is provided between the air cooler and the flon refrigeration circuit,
The CFC-based refrigeration circuit disposed in the machine room or the like cools and condenses high-temperature and high-pressure CFC-based refrigerant gas compressed by a compressor with a condenser, and passes the liquefied CFC-based refrigerant liquid with a liquid cooler. A CFC refrigeration circuit for producing a low-pressure chlorofluorocarbon refrigerant liquid by cooling with an expansion valve after cooling, and further adding a CO ₂ liquefaction unit to the machine room or the like without removing the CFC refrigeration circuit. Set up
The additionally installed CO ₂ liquefaction unit includes a surge drum to which a low-pressure fluorocarbon refrigerant manufactured in the fluorocarbon refrigeration circuit is supplied, and a cascade capacitor through which the fluorocarbon refrigerant from the surge drum flows. And a cascade structure in which a CO ₂ receiver that stores the CO ₂ refrigerant cooled and liquefied by the low-pressure chlorofluorocarbon refrigerant in the cascade condenser is disposed in order from above , and cascaded with the surge drum between the capacitor to form a circulation line which naturally circulates the fluorocarbon refrigerant and CO ₂ liquefaction unit additionally forming a circulation line for natural circulation of CO ₂ refrigerant between the cascade condenser and CO ₂ receiver Setting step,
A switching step of switching the connection between the air cooler disposed in the food freezer compartment and the CO ₂ receiver in the machine room or the like from the fluorocarbon refrigerant circulation line to the CO ₂ circulation line, and the air cooler Is remodeled into an air cooler that freezes food using CO ₂ refrigerant. Piping of the flon-based refrigerant which connects the cascade condenser and said surge drum, and Te the CO ₂ refrigerant pipe odor that connects the CO ₂ liquid receiver and the cascade condenser, the piping liquids are flowing the inlet side is connected to the lower part of the device, a pipe inlet side of gas is flowing, the existing remodeling process of food freezing equipment according to claim 1, characterized in that connected to the top of the device. Said cascade condenser, the existing remodeling process of food freezing equipment according to claim 1 or 2, characterized in that the plate shell heat exchanger.

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