JPH0418218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy-saving refrigeration system, that is, a heat pump and a refrigerator, which can reduce power consumption of a refrigeration compressor.

In a conventional heat pump for producing hot water, which is a type of refrigeration equipment, for example, there is no partition in the condenser, and the entire refrigerant gas discharged by the final stage impeller of the compressor is kept at a temperature level, e.g. 80
To obtain hot water at 85°C, a method has been adopted that condenses water at 85°C. Therefore, for example, 40℃ hot water can be heated to 80℃.
In order to increase the temperature to There was a temperature difference of 45°C between the water inlet and the above-mentioned 85°C refrigerant outlet, resulting in a large energy loss. Furthermore, the difference in temperature between the refrigerant in the evaporator and the fluid to be cooled (heat source water) is large, resulting in large energy losses, which increases the power consumption of the refrigeration compressor.

In order to deal with the above-mentioned problems, a plurality of independent condensers and evaporators are communicated with each compressor to form a separate heat pump circuit, and each condenser in these heat pump circuits are connected in series so that the heated fluid flowing through the condenser increases the temperature while exchanging heat,
In addition, an energy-saving heat pump has been proposed in which the heated fluid flowing in each evaporator and the heated fluid flowing in each condenser are connected to each other by a countercurrent heat pump circuit. 55−
134254), and a refrigeration system in which two or more mutually independent condensers and evaporators are housed in a single shell divided by a partition wall has already been proposed ( (Refer to Japanese Patent Application Laid-Open No. 56-23671).

However, each of the above proposals,
Since it is composed of individual refrigerant circuits, there are problems in that the equipment becomes larger and costs increase, and the lubricating oil supplied to the bearings of the compressor of the high-temperature side refrigerator Due to the high pressure inside, a large amount of refrigerant dissolves, which causes problems such as a decrease in the viscosity of the lubricating oil and a forming phenomenon, which in the worst case can lead to damage to the shaft main body. .

In particular, this tendency was remarkable because the higher the performance of the refrigerant, the higher the amount of dissolution.

The present invention solves the above problems of the prior art and reduces the compressor pressure by minimizing the difference between the temperature level of the refrigerant gas that radiates heat to hot water in the condenser and the temperature of the hot water passing through it. In addition to saving energy by reducing the compression work of the stages, by using the same refrigerant system, it can be treated as one container, which not only facilitates pressure resistance and airtightness tests and maintenance, but also It is an object of the present invention to provide a refrigeration system in which the characteristics of the lubrication system are improved by maintaining the lubrication system of the machine at the suction pressure of the refrigerant circuit.

In order to achieve the above object, the present invention provides a refrigeration system comprising an evaporator, a plurality of condensers, a plurality of compression stages for sending compressed gas, a plurality of pressure reducing devices, piping connecting these devices, etc. , the plurality of compression stages are constituted by a multi-stage compressor in which the stage chambers are communicated with each other, and the condenser is constituted by a single condenser whose interior is partitioned into a plurality of chambers having different pressures. A part of the refrigerant gas discharged from at least one stage chamber of the multistage compressor to the next stage chamber is divided and sent to each partition chamber of the condenser with a corresponding pressure, Each partition of the condenser and the corresponding pressure stage of the multi-stage compressor are communicated separately, and each of the adjacent partitions of the condenser is communicated via a pressure reducing device, and a final low-pressure side partition, The refrigerant circuit is connected to the evaporator via a pressure reducing device, and a part of the refrigerant circuit is connected to each stage chamber of the compressor, so that the entire refrigerant circuit is configured as one refrigerant circuit, and the lubrication system of the compressor It is characterized by being configured to maintain the pressure at the suction pressure of the refrigerant circuit.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of essential parts of a multi-stage turbo refrigeration system showing a first embodiment of the present invention. The refrigeration system consists of a compressor A, a condenser B, and an evaporator C, and in the case of this embodiment, the compressor A is equipped with four impellers 1,
A communication pipe 2 leading to the condenser B is connected from the middle of each communication path between each of the impeller chambers A ₂ and A ₃ in the second and subsequent stages and the impeller chambers A ₃ and A ₄ in the next stage, and the refrigerant gas is The pressure is pressurized by each impeller 1 and sent to the next stage impeller chamber, but a part of the pressure is divided and passed through the connecting pipe 2 from the impeller chambers A ₂ and A ₃ separately to the condenser B. It is now sent to the corresponding partition. Furthermore, below the intermediate position between the impeller chambers A ₁ and A ₂ of the first and second stages of the compressor A, there is a communication pipe for communicating with the partition chambers C ₁ and C ₂ of the evaporator C. 4 is connected, and a capacity control valve 5 is provided in the middle.

The condenser B is the same as the conventional one in that a large number of cooling pipes 6 through which hot water flows are provided inside, but the inside is divided into a plurality of partitioned chambers B 12 , ₁₂ by partition walls 7 .
B ₃ and B ₄ , the first partition B ₁₂ is connected to the communication path of the second stage impeller chamber A ₂ of the compressor, and the second and third partition chambers B ₃ and B ₄ are connected to the compressor. The impeller chambers A ₃ and A ₄ of the third and fourth stages are connected to communication passages through communication pipes 2, respectively. In addition, in order to guide the refrigerant liquid condensed in each partition from the high pressure side B ₄ to the low pressure sides B ₃ to _{B 12} sequentially, a pressure reducing valve 1 is installed at the bottom of each partition.
Conduits 17, 18 with 5, 16 are provided.

In addition, the evaporator C is provided with a cooled tube 9 for heat exchange at the lower part, and is divided into chambers C ₁ and C ₂ by a partition wall 11.
The refrigerant liquid to the chamber _C1 is introduced from the condenser B through the connecting pipe 8 and the expansion valve ₁₂ , and the refrigerant liquid to the chamber C1 is introduced into the chamber _C2 through the conduit 20 and the expansion valve 19.
It is introduced at a lower pressure. Further, the evaporated refrigerant gas is configured to be returned from the chamber C ₁ to the intermediate chamber between the first and second impeller chambers through the communication pipe 4 and from the chamber C ₂ to the inlet of the first impeller. There is.

According to this embodiment, when the impeller 1 of the compressor A rotates, the refrigerant gas is pressurized by each impeller 1 and is divided and sent to the corresponding condenser chamber as described above. Here, the refrigerant gas in each chamber is cooled and liquefied by exchanging heat with the hot water passing through the cooling pipe 6, but at this time, the pressure of the refrigerant gas sent into each partition of the condenser is gradually increased. The temperature level (condensation temperature) of the refrigerant gas also increases gradually from room _B12 to room _B4 . In this way, the condensation temperature required by each condenser compartment can be kept at (hot water temperature passing through each compartment + appropriate temperature difference), so the compression work of each stage of the compressor is reduced compared to conventional partitions. Compared to a condenser without a chamber (single chamber condenser), it requires less energy, resulting in energy savings. Furthermore, when the refrigerant condensate enters _B3 from _B4 through the pressure reducing valve 15, a portion of it flashes due to the temperature difference between the refrigerant liquids in chambers _B4 and _B3 . The flash steam heats the cooling pipe passing through _B3 . The same thing is done in chamber B ₁₂ , and with the same amount of refrigerant circulation, the heating capacity is increased compared to the case where the refrigerant is returned from each compartment directly from the condensing chamber to the evaporation chamber. Therefore, the required power is reduced for the same heating capacity. The refrigerant liquid sent to the first partition chamber _C1 of the evaporator C through the expansion valve 12 expands to an intermediate pressure between the first and second stages of the compressor, and a portion evaporates to become refrigerant at an intermediate temperature. becomes gas,
It is separated from the liquid, passes through the eliminator 10, and is sucked into the compressor chamber between the first and second stages through the connecting pipe ₄ . When cooling the fluid to be cooled flowing through the cooling pipe 9 by the second partition chamber _C2 whose pressure is further reduced through the pressure reducing valve 19 and evaporated, the temperature of the fluid and the evaporation temperature of the refrigerant gas in each chamber are Since the difference between the

Further, according to this embodiment, a part of the refrigerant gas discharged from each impeller chamber of the second and subsequent stages of the multistage compressor to the impeller chamber of the next stage is diverted to the partition chamber of the corresponding condenser. Part of the refrigerant circuit is
Since each impeller chamber from the stage onward is connected and the entire refrigerant circuit is composed of one refrigerant circuit, as shown in Figure 6, the multi-stage impeller A suction side bearing 102a and a discharge side bearing 102b are used to support the axle 101 at both ends.
Both bearing chambers 103a and 103b respectively housed
is connected to the oil tank 106 which is communicated with the suction side of the compressor via the balance passage 105 and maintained at a low pressure.
It is possible to communicate through the passages 104a and 104b, and therefore, even if high-temperature, high-pressure refrigerant gas on the discharge side leaks into the discharge-side bearing chamber 103b during operation, the bearing chamber 103b is kept at a low pressure as described above. Therefore, only a small amount of refrigerant gas dissolves into the lubricating oil that is forcibly lubricated via the oil pump 107, oil cooler 108, and lubricating oil circuit 109, thereby preventing deterioration of the lubricating oil. This allows the bearing to be used for a long period of time.

FIG. 3 shows a second embodiment. In this embodiment, the condenser B is divided into three partition chambers B ₁₂ , B 3 , and B ₄ as in the first embodiment (FIG. 2), and the refrigerant liquid in the high pressure chamber B ₄ is divided into three partition chambers B 12 , B ₃ , and B 4 . 16, the liquid is sequentially transferred to the low pressure chambers, and from chamber B ₁₂ , it passes through the connecting pipe 8, passes through the expansion valve 12, and is sent to the conventional evaporator C consisting of a single chamber.

According to this embodiment, each time the refrigerant liquid flows from the high-pressure chamber to the low-pressure chamber of the condenser, a portion of the refrigerant liquid flashes, and the generated steam heats the cooling pipe passing through the low-pressure chamber, increasing the heating capacity. Furthermore, since the temperature difference between the temperature level (condensation temperature) of the refrigerant gas in the condenser B and the hot water passing through each partition is reduced, the compression work of the compressor is reduced, and energy can be saved.

FIG. 4 shows a third embodiment. In this embodiment, the condenser B is divided into three chambers B ₁₂ , B ₃ and B ₄ as in the first and second embodiments (FIGS. 2 and 3);
In addition, the evaporator C is equipped with a cooled pipe 9 _.
An economizer C _E is attached adjacent to the chamber, and both chambers are connected via an expansion valve 19 at the bottom. This economizer C _E has a structure different from the partition chamber C ₁ in the first embodiment (FIG. 2) in that the cooled pipe 9 is not provided inside.

According to this embodiment, as in the first and second embodiments, in the condenser B, the temperature difference between the temperature level of the refrigerant gas dissipating heat to the hot water in each partition and the hot water passing therethrough is reduced. Therefore, the compression work of the compressor is reduced. Furthermore, since the cooling pipe of the low pressure chamber is heated by the flash steam generated each time liquid enters the low pressure chamber from the high pressure chamber of the condenser through the pressure reducing valve, the heating capacity is increased. Also, evaporator C
In this case, as in the first embodiment (FIG. 2), the refrigerant liquid led through the expansion valve 12 enters the economizer.
The refrigerant liquid expands to an intermediate pressure in C _E , partially evaporates, becomes refrigerant gas, and returns to the compressor room between the first and second stages. The pressure is further reduced by the expansion valve 19, and the temperature of the chamber _C2 is lowered to perform a cooler function.

In each of the above embodiments, a turbo compressor equipped with a multi-stage centrifugal impeller has been described as a compressor, but it goes without saying that screw type or reciprocating positive displacement compressors are also included.

Regarding the partitioning method, it is of course possible to partition in the axial direction as shown in FIG. 5, instead of partitioning in a ring type (perpendicular to the axis) as shown in FIG. 2 and other figures.

As explained above, according to the present invention, a plurality of compression stages in a refrigeration system are configured by a multi-stage compressor in which the stage chambers are communicated with each other, and the condenser is configured by a multi-stage compressor having internal pressures different from each other. Consisting of a single condenser partitioned into a plurality of chambers, a part of the refrigerant gas discharged from at least one stage chamber of the multistage compressor to the next stage chamber is divided to reduce the pressure corresponding to the above. By connecting a part of the refrigerant circuit to each stage chamber of the compressor so that the refrigerant is sent to each partition chamber of the condenser, and configuring the refrigerant circuit as a whole into one refrigerant circuit, the following effects can be achieved.

() Since the condensation temperature required by each condenser compartment can be kept to a level that adds an appropriate temperature difference to the temperature of the hot water passing through each compartment, the compression work of each stage of the compressor can be reduced compared to conventional partitions. Compared to those without a chamber, it requires less space and saves energy.

() By having one refrigerant circuit as a whole and using the same refrigerant system, it is possible to treat it as one container, which makes pressure resistance and airtightness tests easier and maintenance easier.

() A multi-stage compressor with multiple compression stages in which the stage chambers are communicated with each other, and the entire refrigerant circuit is configured as a single refrigerant system to support both ends of the multi-stage compressor. It is possible to maintain the pressure in both bearing chambers at a low pressure (equivalent to the evaporator pressure) on the suction side of the compressor via the balance passage, and in this way the compressor lubrication system is maintained at the suction pressure of the refrigerant circuit. With this structure, it is possible to reduce the amount of high-temperature, high-pressure refrigerant gas dissolved in the lubricating oil on the discharge side during operation, prevent deterioration of the lubricating oil, and enable long-term use of the bearing. , it becomes possible to obtain a high-performance heat pump that can obtain high temperatures.

[Brief explanation of drawings]

Figure 1 shows the changes in the refrigerant condensation temperature a, hot water temperature b, cooled fluid temperature c, and refrigerant evaporation temperature d in the condenser and evaporator when a conventional refrigeration system is used as a heat pump. Line diagram. 2 to 4 show the first to third parts of the refrigeration system of the present invention.
FIG. 5 is a sectional view of the main part of the embodiment, FIG. 5 is a sectional view taken along a plane perpendicular to the axis showing another example of partitioning the condenser and evaporator, and FIG. 6 is a cross-sectional view of the refrigerator multi-stage compressor of the present invention. FIG. 2 is an explanatory diagram showing a forced lubrication circuit for a bearing. A... Compressor, B... Condenser, C... Evaporator,
_A1 to _A4 ...impeller chamber, _B12 to _B4 ...condenser partition, _C1 , C...evaporator partition.

Claims (1)

[Claims] 1. In a refrigeration system consisting of an evaporator, multiple condensers, multiple compression stages for sending compressed gas, multiple pressure reducing devices, piping connecting these devices, etc., the multiple compression stages are connected to each stage chamber. The condenser is composed of a single condenser whose interior is partitioned into a plurality of chambers having different pressures, and at least one of the multistage compressors A part of the refrigerant gas discharged from one stage chamber to the next stage chamber is divided and sent to each partition chamber of the condenser corresponding to the pressure, and the refrigerant gas is divided between each partition chamber of the condenser and the multistage compressor. The corresponding pressure stages are communicated separately, the adjacent partitions of these condensers are communicated via a pressure reducing device, and the final low pressure side partition is connected to the evaporator via a pressure reducing device. A part of the refrigerant circuit is connected to each stage chamber of the compressor so that the entire refrigerant circuit is constituted by one refrigerant circuit, and the lubrication system of the compressor is maintained at the suction pressure of the refrigerant circuit. This is an energy-saving refrigeration device that is characterized by: