JP2008014533A - Oil recovering device of compression type refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil recovering device of a compression type refrigerating machine capable of efficiently recovering a lubricant leaked out in a refrigerant cycle to an oil circulation system without energy loss in recovering. <P>SOLUTION: This oil recovering device 1-1 of the compression-type refrigerating machine recovers the lubricant in a refrigerant by introducing the refrigerant in piping 32 from an evaporator 11 to a lubricant tank 25 connected to a suction portion of a compressor 13 by an equalizer pipe 30 through an oil recovering heat exchanger 47 heated by the refrigerant in piping 38 from a condenser 17 toward the evaporator 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oil recovery apparatus for a compression type refrigerator that recovers lubricating oil leaked during a refrigerant cycle.

  Conventionally, a compression refrigerator (vapor compression refrigerator) is configured by connecting a compressor driven by an electric motor, a condenser, and an evaporator with a refrigerant pipe. Lubricating oil is used for lubrication for bearings that support the shafts of the compressor and the motor in a freely rotatable manner, speed increasing gears, and the like. The lubricating oil is compatible with the refrigerant.

  In many cases, the compressor is hermetically sealed, including the motor, bearings, and speed-up gear (not required if the motor and impeller are directly connected), and does not have a shaft seal that penetrates the casing (sealed). Type turbo refrigerator). In this method, it is usually inevitable that a small amount of lubricating oil leaks out from the bearing or the speed increasing gear and enters the refrigerant. The leaked lubricating oil accumulates in the evaporator or compressor suction part in the refrigeration cycle during operation. In addition, due to the long-term leakage of lubricating oil, lubrication failure due to lack of oil in the lubricating oil system occurs. In addition, when lubricating oil is mixed or dissolved in the refrigerant system and accumulates, problems such as deterioration of heat transfer on the refrigerant side and further change in the refrigerant vapor pressure characteristics occur.

  As a countermeasure against this, conventionally, lubricating oil is recovered from the refrigerant circulation system. That is, the refrigerant mixed with the lubricating oil is heated and evaporated to increase the concentration of the lubricating oil in the refrigerant and recovered in the oil circulation system. For example, the oil-mixed refrigerant that accumulates in the compressor suction section is heated with the discharge steam of the compressor to evaporate the refrigerant, the lubricating oil concentration is increased, and the refrigerant vapor is sucked into the compressor (see, for example, Patent Document 1), A refrigerant with high lubricating oil concentration is collected and heated to evaporate the refrigerant. The evaporated refrigerant is returned to the evaporator, and the heating source at that time uses a discharge steam of a compressor, a heater or lubricating oil (for example, Patent Document 2).

  The refrigerant liquid in which oil is dissolved should be sucked into the compressor after exhibiting the refrigeration effect. However, in the above conventional method, it is different from cold water (a target that exhibits the refrigeration effect, the fluid to be cooled). Evaporates with heat from a fluid or heat source. That is, the evaporated refrigerant does not exhibit the refrigeration effect, but becomes a load on the compressor, thereby reducing the efficiency of the refrigerator.

  On the other hand, even if the lubricating oil concentration in the refrigerant is increased and recovered in the oil circulation system, if the refrigerant concentration in the recovered lubricating oil is high, the viscosity of the refrigerant circulation system (oil temperature management) causes the higher refrigerant concentration to be vaporized. Will be released in the form of That is, among the refrigerant liquid in the recovered liquid returned to the oil circulation system together with the lubricating oil, the refrigerant concentration higher than the refrigerant concentration of the oil circulation system lubricating oil becomes refrigerant vapor without producing the refrigeration effect. There is a problem of reducing efficiency.

  The refrigerant mist from the evaporator is sucked into the compressor suction portion. In patent document 1, it is set as the structure which heats the refrigerant | coolant collected in the suction part and raises oil concentration. In patent document 2, it is comprised so that the refrigerant | coolant with as high an oil concentration as possible may be attracted | sucked. However, the oil concentration returned to the oil circulation system is not managed.

In particular, when the temperature of the chilled water (cooled medium) is high, such as when the refrigerator is started, and the load on the evaporator increases, the amount of refrigerant mist sucked into the compressor suction section increases, and the oil concentration in the mist is Even if the oil is concentrated and returned to the oil circulation system, it will be much lower than the concentration during normal operation. Oil can even spill into the circulatory system. Also, when the cold water temperature is high at startup and the evaporation temperature of the evaporator is higher than the chiller installation atmosphere, the refrigerant vapor condenses in the compressor body, etc., and the compression suction bottom (or tank) together with the refrigerant mist It collects in. In this case, the oil concentration in the refrigerant is reduced, and even if it is concentrated by heating and returned to the oil circulation system, the oil concentration in the refrigerant is much lower than that during normal operation. It overflows with a large amount of refrigerant and may even flow out into the refrigerant circulation system.
Japanese Utility Model Publication No. 58-22064 JP-A-61-180860

  The present invention has been made in view of the above points, and an object of the present invention is to provide a compression refrigeration capable of efficiently recovering lubricating oil leaked into the refrigerant cycle in the oil circulation system without energy loss during recovery. It is to provide a machine oil recovery device.

According to the first aspect of the present invention, a compressor, a condenser, and an evaporator are connected by a refrigerant pipe that circulates a refrigerant, and a bearing that rotatably supports the shaft of the compressor is made of lubricating oil. In a compression type refrigerator to be lubricated, a tank connected to a compressor suction section through an oil recovery heat exchanger that heats the refrigerant in the evaporator with refrigerant flowing from the condenser to the evaporator, or The lubricating oil in the refrigerant is recovered by being introduced into the bottom of the compressor suction portion.
The tank connected to the compressor suction part is a concept including a lubricating oil tank installed in an oil circulation system. The bottom part of the compressor suction part is a bottom part of a casing provided outside the compressor suction nozzle so as to cover the nozzle. In addition, the refrigerant from the condenser to the evaporator includes the refrigerant from the economizer to the evaporator or the refrigerant from the condenser to the economizer in the case of a refrigeration system in which an economizer is installed between the condenser and the evaporator. It is.

  The invention according to claim 2 of the present application is characterized in that the connection position of the refrigerant pipe for introducing the refrigerant from the evaporator to the oil recovery heat exchanger with the evaporator is the cold water inlet side of the evaporator. Item 1. The oil recovery device for a compression refrigerator according to Item 1.

  The invention according to claim 3 of the present application adjusts the flow rate of the refrigerant in the refrigerant pipe for introducing the refrigerant from the evaporator to the oil recovery heat exchanger according to the degree of superheat of the refrigerant that has passed through the oil recovery heat exchanger. 3. An oil recovery apparatus for a compression refrigeration machine according to claim 1, further comprising an adjusting means.

The invention according to claim 4 of the present application is characterized by comprising heating means for heating the tank or the liquid reservoir at the bottom with a refrigerant directed from the condenser to the evaporator. It is in the oil collection | recovery apparatus of the compression-type refrigerator as described in above.
The refrigerant that goes from the condenser to the evaporator is a concept that includes the refrigerant that goes from the economizer to the evaporator or the refrigerant that goes from the condenser to the economizer in the case of a refrigeration system in which an economizer is installed between the condenser and the evaporator. is there. Moreover, you may use together with the said oil recovery heat exchanger.

According to the fifth aspect of the present invention, the compressor, the condenser, and the evaporator are connected by a refrigerant pipe that circulates the refrigerant, and a bearing that rotatably supports the shaft of the compressor is made of lubricating oil. In a compression type refrigerator to be lubricated, a tank for collecting a mixed solution of lubricating oil and a refrigerant or a bottom of a compressor suction portion, means for detecting or estimating a concentration of the mixed solution in the tank or the bottom, and the tank Or it has a means to move a mixed solution from the bottom to an oil circulation system, and it is in an oil recovery device of a compression refrigerator.
When the oil concentration of the mixed solution in the tank is low, the movement of the mixed solution to the oil circulation system is prohibited.

  In the invention according to claim 6 of the present application, the means for detecting the concentration of the mixed solution in the tank or the bottom is a relationship between the dew point of the mixed solution, the compressor suction portion temperature or the evaporator refrigerant temperature, and the temperature of the mixed solution. Or a means for determining the concentration of the mixed solution from the relationship between the vapor pressure of the tank or the bottom or the pressure of the compressor suction or the pressure of the evaporator and the temperature of the mixed solution. It is in the oil recovery device of the compression type refrigerator according to claim 5 characterized by the above-mentioned.

According to the seventh aspect of the present invention, the means for estimating the concentration of the mixed solution in the tank or the bottom is such that the liquid level of the lubricating oil in the lubricating oil tank provided in the oil circulation system is a predetermined liquid level. A means for detecting that the evaporator pressure or the evaporator temperature has reached a predetermined value, or a means for detecting that a predetermined time has elapsed since the start of the refrigerator. It exists in the oil recovery apparatus of the compression type refrigerator of Claim 5.
The liquid level is detected by a liquid level sensor or a liquid level switch. When the high level of the liquid level is detected, when the evaporator pressure is high, when the evaporation temperature is high, or for a predetermined time after starting the refrigerator, the movement of the mixed solution into the oil circulation system is prohibited.

  When the lubricating oil concentration in the mixed solution is estimated to be lower or lower than a predetermined value, the invention according to claim 8 of the present application prohibits the movement of the mixed solution to the oil circulation system, and the tank or the The oil recovery apparatus for a compression refrigeration machine according to any one of claims 5 to 7, further comprising means for returning the mixed solution in the bottom to the refrigerant circulation system.

  According to the first aspect of the present invention, the refrigerant mixed with oil is heated by the refrigerant introduced from the condenser to the evaporator, and the refrigerant evaporated by being heated is sucked into the compressor. At this time, since the refrigerant introduced into the evaporator is cooled (the same amount of heat), the same amount of heat as that of the evaporated refrigerant is the same as when the refrigeration effect is exhibited in the evaporator. Therefore, the lubricating oil leaked during the refrigerant cycle can be efficiently recovered in the oil circulation system without energy loss during recovery.

  According to the second aspect of the present invention, effective recovery of the lubricating oil is achieved. That is, since the temperature difference between the cold water temperature and the refrigerant temperature is larger on the cold water inlet side of the evaporator, the refrigerant is boiled more rapidly, and the refrigerant evaporates more, and the remaining refrigerant liquid contains a lot of lubricating oil. . Therefore, if it comprises like invention of Claim 2, the ratio of the lubricating oil in the refrigerant | coolant introduce | transduced into an oil collection | recovery heat exchanger can be increased, and more effective collection | recovery of lubricating oil is achieved.

  According to the invention described in claim 3, the amount of refrigerant introduced into the oil recovery heat exchanger can be maintained at an appropriate value.

  According to invention of Claim 4, the heating of the mixed solution of lubricating oil and a refrigerant | coolant can be performed efficiently.

  According to invention of Claim 5 thru | or 8, according to the oil concentration of a mixed solution, the movement to the oil circulation system of a mixed solution and its prohibition can be performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is an overall schematic configuration diagram of a compression refrigerator 1-1 configured by using the first embodiment of the present invention. As shown in the figure, the compression refrigerator 1-1 is a compression refrigerator that performs a vapor compression refrigeration cycle, and is composed of a closed system in which a refrigerant is enclosed. An evaporator 11 that removes heat from the cooling fluid) and evaporates the refrigerant to exert a refrigeration effect; a compressor 13 that is rotationally driven by an electric motor (driver) 15 to compress the refrigerant vapor into high-pressure vapor; A condenser 17 that cools and condenses steam with cooling water (cooling fluid) and an expander 19 that decompresses and expands the condensed refrigerant and sends it to the evaporator 11 are connected by a refrigerant pipe 21 that circulates the refrigerant. Configured. Further, the compression refrigerator 1-1 includes a control device (control means) (not shown) that performs drive control of the electric motor 15 and various pumps, open / close control of various open / close means, and the like. The shafts of the compressor 13 and the electric motor 15 are rotatably supported by a bearing 23, and the bearing 23 is lubricated with lubricating oil. In FIG. 1, the impeller 13a of the compressor 13 and the electric motor 15 are directly connected. However, the impeller 13a may be driven by increasing the rotation of the electric motor 15 with a speed increasing gear. In that case, the speed increasing gear is also lubricated with lubricating oil.

  The compression refrigerator 1-1 includes a lubricating oil tank 25 that stores lubricating oil for lubricating the bearing 23 of the compressor 13. In this embodiment, the bearings 23 are installed on both sides of the electric motor 15. A pipe 29a for supplying the lubricating oil to the bearing 23 via the oil pump 27 and a pipe 29b for returning the lubricating oil that has lubricated the bearing 23 to the lubricating oil tank 25 are attached to the lubricating oil tank 25. 29b, the lubricating oil tank 25, and the oil pump 27 constitute an oil circulation system. If the bearing 23 is a rolling bearing, the allowable viscosity range of the lubricating oil can be made wider than that of the conventional sliding bearing, and management of the lubricating oil becomes easy.

  The lubricating oil tank 25 has a lubricating oil liquid level, the upper part of which is refrigerant vapor, and the lower part is lubricating oil mixed with the refrigerant (hereinafter referred to as “mixed solution” depending on the case). The piping 29 a is connected to the lower portion of the lubricating oil tank 25, so that the mixed solution of lubricating oil and refrigerant in the lubricating oil tank 25 is sent to the bearing 23 by the oil pump 27, and the piping 29 b is connected to the upper portion of the lubricating oil tank 25. The mixed solution returned from the bearing 23 by being connected is introduced into the refrigerant vapor space of the lubricating oil tank 25. The upper part of the lubricating oil tank 25 and the suction part of the compressor 13 are connected by a pressure equalizing pipe 30 so that the refrigerant vapor in the upper part of the lubricating oil tank 25 is introduced into the compressor 13.

  The compression refrigerator 1-1 includes oil recovery means for recovering oil from the refrigerant of the evaporator 11 and returning it to the lubricating oil tank 25. The oil recovery means connects the lubricating oil tank 25 in which the refrigerant containing the oil in the evaporator 11 is connected to the suction portion of the compressor 13 by the pressure equalizing pipe 30 via the oil recovery heat exchanger 47. In the refrigerant, the refrigerant passing through the oil recovery heat exchanger 47 is heated by the refrigerant (pipe 38) from the condenser 17 to the evaporator 11. It is structured to collect the lubricating oil. That is, the refrigerant in the evaporator 11 is guided to the oil recovery heat exchanger 47 and heated by the refrigerant from the condenser 17 to the evaporator 11. As for the amount of refrigerant from the evaporator 11 to the oil recovery heat exchanger 47, the degree of superheat after evaporation is detected by the superheat degree detecting means 49, and the opening degree of the valve 51 is controlled so that this superheat degree becomes a predetermined value. This is done by the adjusting means 52 that adjusts accordingly. This superheated steam entrains a refrigerant liquid having a high oil concentration along the tube wall in the form of a liquid film and enters the lubricating oil tank 25. The refrigerant vapor is sucked into the suction side of the compressor 13 through the pressure equalizing pipe 30. By adjusting the degree of superheat, it is not necessary to introduce excess refrigerant liquid into the oil recovery heat exchanger 47.

  In the suction portion of the compressor 13, refrigerant liquid mist accompanying the refrigerant vapor from the evaporator 11 is accumulated. The refrigerant liquid mist is contained in a form in which the lubricating oil is concentrated, is not easily evaporated, and accumulates at the bottom 40 of the suction portion. In order to increase the oil concentration of the accumulated liquid (mixed solution of refrigerant and lubricating oil), the liquid is heated by the refrigerant (heating means 35 provided in the pipe 34) from the condenser 17 toward the evaporator 11. Refrigerant vapor evaporating from the heated mixed solution is sucked into the impeller 13a through the gap between the suction portions. As shown in FIG. 4, the concentration of the mixed solution of the refrigerant and the lubricating oil can be known from the refrigerant dew point temperature and the mixed solution temperature (FIG. 4 shows a case where R245fa is used as the refrigerant and polyol ester is used as the lubricating oil. Ring diagram). While controlling this concentration, the mixed solution in the bottom 40 is lubricated by the piping 45 connecting the bottom 40 of the suction portion of the compressor 13 and the lubricating oil tank 25 and the opening / closing means (valve) 43 connected to the piping 45. By returning to the tank 25, it is possible not to apply an extra load to the compressor 13. The oil circulation system receives heat due to mechanical friction loss at the bearing 23, the lubricating oil in which the refrigerant is dissolved is heated, and the refrigerant evaporates. In order to lower the lubricating oil temperature, it is possible to make the refrigerant concentration in the lubricating oil tank 25 higher than that in the other oil circulation system and adjust the temperature with the refrigerant vapor. In this figure, for example, the target concentration of the mixed solution to be heated and concentrated is set so that the oil circulation system reaches a predetermined temperature, and the hot water temperature of the lubricating oil system is adjusted, and the oil that cools the lubricating oil Installation of a cooler is omitted (oil cooling is consciously mixed with a lubricant in the lubricating oil system).

  The means for detecting the concentration of the mixed solution includes means for obtaining the concentration of the mixed solution from the relationship between the dew point of the mixed solution and the temperature of the mixed solution, the relationship between the compressor suction portion temperature and the temperature of the mixed solution, or evaporation. Similarly, the concentration of the mixed solution may be obtained from the relationship between the refrigerant temperature and the temperature of the mixed solution. Further, the concentration of the mixed solution may be obtained from the relationship between the vapor pressure at the bottom 40 of the suction portion, the compressor 13 suction portion pressure, the evaporator 11 pressure, the specific gravity of the mixed solution, and the temperature of the mixed solution.

  In this compression type refrigerator 1-1, two portions to be heated by the refrigerant liquid from the condenser 17 to the evaporator 11 are provided (oil recovery heat exchanger 47 and heating means 35), but only one of them is provided. Even if provided, there is an effect. In the case of a refrigerator having an economizer between the condenser 17 and the evaporator 11, the efficiency is slightly inferior, but the refrigerant from the economizer to the evaporator 11 or the refrigerant from the condenser 17 to the economizer The mixed solution may be heated.

  The opening / closing means 43 of the mixed solution recovery line (pipe 45) from the suction portion of the compressor 13 to the lubricating oil tank 25 is not based on the concentration of the mixed solution, but for a predetermined time from the start of the compression refrigerator 1-1. Even with a simple method of closing, recovery of a mixed solution containing a large amount of refrigerant and having a low oil concentration can be avoided (the oil concentration of the mixed solution is low for a predetermined time from the start).

  That is, in the compression refrigerator 1-1, the concentration of the mixed solution in the bottom portion 40 of the suction portion of the compressor 13 is detected, and when the lubricating oil has a predetermined concentration or more, the mixed solution is supplied from the bottom portion 40 to the oil circulation system. It is recovered (moved) to the oil circulation system by the piping 45 and the opening / closing means 43 which are moving means. A tank connected to the suction portion of the compressor 13 is installed in place of the bottom portion 40 to detect its concentration, and when the measured concentration is equal to or higher than the predetermined concentration, this mixed solution is recovered (moved) to the oil circulation system. ). When a tank is separately connected to the suction portion of the compressor 13, if this tank is positioned higher than the lubricating oil tank 25 (the lubricating oil tank 25 is lower than the tank) and both tanks are configured to have substantially the same pressure, The mixed solution can be recovered from the tank to the lubricating oil tank 25 by the position head. If this tank is connected to the compressor suction pressure and the pressure equalization, and the lubricating oil tank 25 pressure is higher, the pressure equalization connection is compressed from the compressor suction side when collecting the mixed solution. By switching to the machine discharge side, the mixed solution can be recovered from the tank to the lubricating oil tank 25.

  In this embodiment, the connection position of the refrigerant pipe 32 with the evaporator 11 is the cold water inlet side of the evaporator 11. This is because the temperature difference between the cold water temperature and the refrigerant temperature is larger on the cold water inlet side of the evaporator 11, and the boiling of the refrigerant is intense, and the refrigerant evaporates more, and the remaining refrigerant liquid contains a lot of lubricating oil. Therefore, the ratio of the lubricating oil in the refrigerant introduced into the oil recovery heat exchanger 47 can be increased, and more effective recovery of the lubricating oil can be achieved.

[Second Embodiment]
FIG. 2 is an overall schematic configuration diagram of a compression type refrigerator 1-2 configured using the second embodiment of the present invention. In the compression refrigeration machine 1-2 shown in the figure, the same or corresponding parts as those in the compression refrigeration machine 1-1 shown in FIG. Items other than those described below are the same as those in the embodiment shown in FIG. In this compression type refrigerator 1-2, the difference from the compression type refrigerator 1-1 is that a power recovery device 63 is installed instead of the expander 19.

  The power recovery device 63 used in this embodiment is a rotary power recovery expander that recovers the energy of the refrigerant flow from the condenser 17 to the evaporator 11, and has a nozzle and a turbine inside. Thus, the flow rate of the refrigerant liquid from the condenser 17 is increased and a swirling flow is applied, and this liquid flow is applied to the turbine to give a rotational force to the turbine. The power recovery device 63 includes a generator (power recovery machine) 65, and the generator 65 recovers the energy of the refrigerant flow as electric power. If the recovered electric power is supplied to the motor 15 and used for a part of the compression work, the input electric power (input power) from the outside can be reduced accordingly. Further, since the power is recovered from the refrigerant entering the evaporator 11 from the condenser 17, the enthalpy of the refrigerant entering the evaporator 11 is lowered, and thus the refrigerating capacity of the evaporator 11 is increased and the refrigeration effect is increased. .

[Third Embodiment]
FIG. 3 is an overall schematic configuration diagram of a compression refrigerator 1-3 configured using the third embodiment of the present invention. In the compression refrigeration machine 1-3 shown in the same figure, the same or corresponding parts as those of the compression refrigeration machine 1-1 shown in FIG. Items other than those described below are the same as those in the embodiment shown in FIG. This compression refrigerator 1-3 is different from the compression refrigerator 1-1 in that the oil recovery means including the oil recovery heat exchanger 47 and the pipe 32 is omitted, while the oil circulation system (the pipe 29a ) Is provided with a cooler 70 for cooling the lubricating oil, and an opening / closing means 43 connected to the piping 45 that connects the bottom 40 of the suction portion of the compressor 13 and the lubricating oil tank 25 is installed in the lubricating tank 25. The controller 44 is configured to control opening and closing so that the liquid level of the lubricating oil measured by the liquid level sensor 41 falls within a predetermined liquid level range.

  As described above, the refrigerant liquid mist having a high lubricating oil concentration accompanying the refrigerant vapor from the evaporator 11 accumulates at the bottom 40 of the suction portion of the compressor 13. In order to further increase the oil concentration of the mixed solution of the accumulated refrigerant and lubricating oil, the refrigerant is heated by the refrigerant (heating means 35) from the condenser 17 toward the evaporator 11. The refrigerant vapor that is heated and evaporates from the mixed solution is sucked into the impeller 13a through the gap between the suction portions. When the liquid level of the lubricating oil tank 25 is below a predetermined level, the mixed solution having a high oil concentration is recovered by the opening / closing means 43 and collected in the lubricating oil tank 25. When the liquid level is high, the opening / closing means 43 is closed and the lubricating oil is collected. It is not introduced into the tank 25. The oil circulation system receives heat due to mechanical friction loss at the bearing 23, and the lubricating oil in which the refrigerant has melted is heated and the refrigerant tends to evaporate. Therefore, there is no problem even if extra refrigerant enters. Since the cooling oil temperature is managed by the cooler 70, the refrigerant concentration in the lubricating oil of the lubricating oil system is not excessively reduced and the refrigerant concentration can be managed by the relationship shown in FIG. Although omitted in FIG. 3, the cooler 70 may be cooled with the refrigerant liquid of the condenser 17, and the evaporated vapor may be returned to the condenser 17 or the evaporator 11, and may be returned to the economizer when an economizer is provided. However, the cooler itself can be placed in the economizer and cooled by the economizer.

  That is, in the compression refrigerator 1-3, the concentration of the mixed solution at the bottom 40 of the suction portion of the compressor 13 is estimated, and when the estimated lubricating oil concentration in the mixed solution is equal to or higher than a predetermined concentration, this is added to the oil circulation system. Is recovered (moved). Further, it is preferable to directly detect the liquid level of the lubricating oil tank 25 in the oil circulation system and move to the oil circulation system while confirming that the lubricating oil tank 25 does not overflow.

  If the liquid level of the lubricating oil tank 25 is high and the return of oil is restricted, the mixed solution will accumulate too much at the bottom 40 of the suction portion of the compressor 13. In this state, it can be estimated that the oil concentration of the solution at the bottom 40 of the compressor 13 is low. Therefore, the excess solution is returned to the evaporator 11 by the pipe 71 connecting the bottom 40 of the suction unit and the evaporator 11. To do. In FIG. 3, the mixed solution at the bottom 40 of the suction portion overflows into the pipe 71. In addition, the liquid seal part 73 is provided in the middle of the pipe 71 to prevent the back flow of the refrigerant. That is, the refrigerant pipe 71 is means for returning the mixed solution in the bottom 40 to the refrigerant circulation system.

  In the said 1st-3rd embodiment, although the refrigerant | coolant with comparatively high lubricating oil concentration is caught by the suction part of the compressor 13, you may catch by another part. That is, a relatively high-concentration refrigerant may be captured by, for example, the evaporator 11 or may be captured by an eliminator section of the evaporator (which separates droplets from refrigerant gas evaporated by the evaporator). Further, these captured mixed solutions are stored in a tank higher than the bottom 40 of the compressor 13 suction part instead of the bottom 40 of the compressor 13 suction part, and are stored in pressure with the suction part of the compressor 13, Furthermore, the mixed solution can be heated and concentrated as necessary. After concentrating in this tank, it is recovered in the lubricating oil tank 25 of the oil circulation system. Even when a tank is used, the same apparatus and method as described above can be applied for concentration management and the like.

  As a means for estimating the concentration of the mixed solution, in this embodiment, a means for detecting that the liquid level of the lubricating oil in the lubricating oil tank 25 has become a predetermined liquid level is used. It can also be estimated by using means for detecting that the reactor pressure or the evaporator temperature has reached a predetermined value, means for detecting that a predetermined time has elapsed after the start of the refrigerator, and the like.

1 is an overall schematic configuration diagram of a compression refrigerator 1-1. It is a whole schematic block diagram of the compression type refrigerator 1-2. It is a whole schematic block diagram of the compression refrigerator 1-3. It is a figure which shows the relationship between mixed solution temperature, a refrigerant | coolant dew point, and a refrigerant | coolant density | concentration.

Explanation of symbols

1-1 Compression Refrigerator 11 Evaporator 15 Electric Motor (Driver)
DESCRIPTION OF SYMBOLS 13 Compressor 17 Condenser 19 Expander 21 Refrigerant piping 23 Bearing 25 Lubricating oil tank 27 Oil pump 30 Pressure equalizing pipe 35 Heating means 40 Bottom part 47 Oil recovery heat exchanger 49 Superheat detection means 51 Valve 52 Adjustment means 1-2 Compression type Refrigerator 63 Power recovery device 1-3 Compressive refrigerator 70 Cooler

Claims (8)

In the compression type refrigerator that connects the compressor, the condenser, and the evaporator with a refrigerant pipe that circulates the refrigerant, and lubricates a bearing that rotatably supports the shaft of the compressor with lubricating oil.
The refrigerant in the evaporator is introduced into the tank connected to the compressor suction section or the bottom of the compressor suction section via an oil recovery heat exchanger that heats the refrigerant from the condenser to the evaporator. By doing so, the oil recovery apparatus of the compression-type refrigerator which collects the lubricating oil in the said refrigerant | coolant is characterized by the above-mentioned.   The compression refrigerator according to claim 1, wherein a connection position of the refrigerant pipe for introducing the refrigerant from the evaporator to the oil recovery heat exchanger with the evaporator is on a cold water inlet side of the evaporator. Oil recovery device.   The refrigerant pipe for introducing the refrigerant from the evaporator to the oil recovery heat exchanger is provided with adjusting means for adjusting the refrigerant flow rate according to the degree of superheat of the refrigerant that has passed through the oil recovery heat exchanger. The oil recovery apparatus of the compression type refrigerator according to claim 1 or 2.   The oil recovery of the compression type refrigerator according to claim 1, 2 or 3, further comprising heating means for heating the tank or the liquid reservoir at the bottom with a refrigerant from a condenser to an evaporator. apparatus. In the compression type refrigerator that connects the compressor, the condenser, and the evaporator with a refrigerant pipe that circulates the refrigerant, and lubricates a bearing that rotatably supports the shaft of the compressor with lubricating oil.
A tank for collecting a mixed solution of lubricating oil and a refrigerant or a bottom portion of a compressor suction portion, means for detecting or estimating a concentration of the mixed solution in the tank or the bottom portion, and an oil mixture from the tank or the bottom portion. An oil recovery apparatus for a compression refrigeration machine comprising a means for moving to a circulation system. Means for detecting the concentration of the mixed solution in the tank or the bottom,
Is the means for obtaining the concentration of the mixed solution from the relationship between the dew point of the mixed solution or the compressor suction part temperature or the evaporator refrigerant temperature and the temperature of the mixed solution,
6. The compression refrigeration according to claim 5, wherein the concentration of the mixed solution is obtained from the relationship between the vapor pressure of the tank or the bottom, the pressure of the compressor suction portion or the evaporator pressure, and the temperature of the mixed solution. Machine oil recovery equipment. Means for estimating the concentration of the mixed solution in the tank or the bottom,
Means for detecting that the level of the lubricating oil in the lubricating oil tank provided in the oil circulation system has reached a predetermined level;
Or means for detecting that the evaporator pressure or the evaporator temperature has reached a predetermined value,
Alternatively, means for detecting that a predetermined time has elapsed after the start of the refrigerator,
The oil recovery apparatus for a compression type refrigerator according to claim 5, wherein   When the lubricating oil concentration in the mixed solution is lower than or lower than the predetermined value, the movement of the mixed solution to the oil circulation system is prohibited, and the mixed solution in the tank or the bottom is made into the refrigerant circulation system. The oil recovery apparatus for a compression type refrigerator according to any one of claims 5 to 7, further comprising a returning means.

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