JP2004300928A - Multistage compressor, heat pump and heat utilization device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multistage compressor in which liquid for cooling is supplied to a flow passage between stages, wherein compressed air can be cooled effectively. <P>SOLUTION: A multistage compressor 12 is provided with a atomization part 31 for generating mist from liquid in a space 35a different from a flow passage 25 between steps and a mist supply part 32 for supplying the mist from the space 35a to the flow passage 25. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-stage compressor for compressing a gas in multiple stages, and more particularly to a technique for cooling a compressed gas.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a multi-stage compressor, there is a technique of supplying a liquid to a flow path between stages for the purpose of cooling a compressed gas or the like (for example, see Patent Document 1). In this technique, liquid is evaporated in a flow path between stages, and the heat of the compressed gas is removed by the latent heat of evaporation. Effective cooling of the compressed gas leads to reduced compression power.
[0003]
[Patent Document 1]
U.S. Pat. No. 2,786,626 [0004]
[Problems to be solved by the invention]
In the above-mentioned technology, there is a problem how to surely evaporate the liquid in the flow path for effective cooling of the compressed gas. Further, when the liquid particles having a large diameter collide with the rotating member in the next stage, there is a possibility that problems such as erosion and vibration may occur.
[0005]
The present invention has been made in view of the above circumstances, and provides a multi-stage compressor capable of effectively cooling a compressed gas in a multi-stage compressor in which a cooling liquid is supplied to a flow path between stages. The purpose is to:
It is another object of the present invention to provide a heat pump capable of improving energy efficiency by reducing compression power.
Another object of the present invention is to provide a heat utilization device that can achieve high energy efficiency.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a multistage compressor of the present invention is a multistage compressor for compressing a gas in multiple stages, wherein an atomizing section that generates mist from a liquid in a space different from a flow path between stages, And a mist supply unit that supplies the mist from the space to the flow path.
In the multi-stage compressor of the present invention, the liquid supplied to the flow path between the stages is previously atomized, and the size of the particle size of the liquid present in the flow path is limited to a small size. Therefore, the liquid easily evaporates in the flow path between the stages, and the occurrence of problems such as erosion due to liquid supply is prevented. The generation of fog is performed reliably and stably by using a space different from the flow path between the stages.
[0007]
In the above multistage compressor, the mist supply unit may be configured to supply the mist from the space to the flow path by using a dynamic pressure of the gas in the flow path.
In this configuration, the kinetic energy of the gas is reduced or eliminated by utilizing the dynamic pressure of the gas.
[0008]
Further, the above-described multi-stage compressor is preferably applied to a case where the static pressure of the flow passage is a negative pressure with respect to the atmospheric pressure.
In this case, there is an advantage that the pressure of the supply source can be low and the liquid (mist) can be easily transported.
[0009]
In the above-mentioned multistage compressor, the liquid may be a liquefied substance of the gas.
In this case, the occurrence of problems due to the mixture of the gas and the liquid (mist), such as the reaction of the gas and the liquid (mist) to generate impurities, is suppressed.
[0010]
A heat pump according to the present invention includes the above-described multistage compressor according to the present invention. In this case, the refrigerant may be water.
[0011]
Further, a heat utilization device of the present invention is a heat utilization device that exchanges heat with a heat source, and includes the heat pump described above.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view schematically showing an embodiment of a multi-stage compressor according to the present invention.
In FIG. 1, a compressor 12 includes a multi-stage (four-stage in this example) centrifugal compressor, and includes a rotating shaft 20 and a plurality of stages attached to the rotating shaft 20 and arranged in multiple stages in the axial direction of the rotating shaft 20. An impeller 21, a driving device 23 for driving the rotating shaft 20, a return channel 25 which is a flow path for guiding gas (gas or vapor) from the impeller 21 of the preceding stage to the impeller 21 of the subsequent stage, and a cooling liquid And a cooling liquid supply device 30 for supplying to the return channel 25.
[0013]
In the compressor 12, when the driving device 23 rotates the rotating shaft 20, gas flows into the compressor 12. The gas is moved outward in the circumferential and radial directions by the rotation of the impeller 21 to increase the pressure, and is guided to the impeller 21 of the next stage through the return channel 25. Thereafter, gas compression is performed in each stage in the same manner. By repeating the compression over a plurality of stages, the pressure of the gas is increased to a desired compression ratio. Further, the compressed gas flowing through the return channel 25 is cooled by the cooling liquid supplied by the cooling liquid supply device 30, and its temperature rise is suppressed.
[0014]
FIG. 2 is a diagram conceptually showing the configuration of the cooling liquid supply device 30.
In FIG. 2, the cooling liquid supply device 30 includes an atomizing unit 31 that generates mist from a cooling liquid, and a mist supply unit 32 that supplies the mist generated by the atomizing unit 31 to the return channel 25. I have.
[0015]
The atomization unit 31 includes a liquid storage tank 35 for storing a liquid for cooling, and an atomizer 36 for atomizing the liquid in the liquid storage tank 35. In addition to the above, the atomization unit 31 includes instruments such as a temperature sensor 37 and a pressure sensor 38, a transportation unit 39 that supplies liquid to the liquid storage tank 35, and controls the amount of liquid in the liquid storage tank 35. A drain valve 40 and the like for performing the operation are appropriately provided as needed. In this example, an ultrasonic atomizer using an ultrasonic vibrator is used as the atomizer 36. The ultrasonic atomizer has an advantage that it can handle various liquids while having a simple configuration. The atomizer is not limited to the ultrasonic type, and various known types can be applied.
[0016]
The mist supply unit 32 has a gas introduction pipe 41 that guides the compressed gas flowing through the return channel 25 to the liquid storage tank 35, and a discharge pipe 42 that discharges the mist together with the compressed gas from the liquid storage tank 35 to the return channel 25. I have. In addition, instruments such as the flow rate control valves 43 and 44 and the temperature sensor 45 are appropriately provided in the mist supply unit 32 as necessary.
[0017]
One end of the gas introduction pipe 41 is connected to the return channel 25, and the other end is connected to the liquid storage tank 35. In the gas introduction pipe 41, an end 41 a on the return channel 25 side is provided so as to protrude from a wall of the return channel 25, and an opening (inlet 41 b) of the end 41 a is provided for the gas flow in the return channel 25. Arranged upstream. That is, the introduction port 41b of the gas introduction pipe 41 is arranged so as to face the flow of the gas. This is because the gas is taken into the gas introduction pipe 41 using the dynamic pressure of the gas flow in the return channel 25.
[0018]
One end of the discharge pipe 42 is connected to the liquid storage tank 35, and the other end is connected to the return channel 25. The end of the discharge pipe 42 on the return channel 25 side is formed so as not to protrude from the wall surface of the return channel 25. This is to suppress an increase in pressure loss of the gas flow in the return channel 25.
[0019]
In the cooling liquid supply device 30, mist is generated from the cooling liquid in the atomization unit 31, and the mist is supplied to the return channel 25 by the mist supply unit 32. That is, the liquid stored in the liquid storage tank 35 is atomized by the atomizer 36, and the mist accumulates in the internal space 35 a of the liquid storage tank 35. On the other hand, a part of the gas flowing in the return channel 25 flows into the gas introduction pipe 41 through the introduction port 41b, and is guided to the liquid storage tank 35. In the liquid storage tank 35, the pressure of the internal space 35 a (the gaseous phase portion including the mist) increases due to the introduction of the gas, and a part of the gaseous phase is discharged into the return channel 25 through the discharge pipe 42. The gas phase discharged to the return channel 25 contains mist, and the mist evaporates in the return channel 25, whereby the compressed gas flowing through the return channel 25 is cooled by the latent heat of evaporation.
[0020]
As described above, in the compressor 12 of the present embodiment, the mist generated in a space different from the flow path between the stages (such as the return channel 25) is supplied to the return channel 25, and the compression of the mist that flows through the return channel 25 due to evaporation of the mist The gas is cooled. Therefore, the size of the particle size of the liquid existing in the return channel 25 is limited to a small size. For example, the particle size of the fog is 20 μm or less, preferably 1 to 10 μm.
[0021]
By limiting the size of the liquid particles to a small size, the surface area per unit volume of the liquid is increased, the evaporation of the liquid in the return channel 25 is promoted, and the time required for the liquid particles to completely evaporate. Is shortened. Therefore, the gas flowing through the return channel 25 is effectively cooled by the latent heat of evaporation. Further, the particles of the liquid hardly collide with the impeller 21 at the subsequent stage, or the diameter of the particles is extremely small even if the collision occurs, thereby preventing the occurrence of troubles in the compressor 12 due to liquid supply such as erosion. The generation of fog is performed in a space different from the flow path between the stages, that is, in the internal space 35 a of the liquid storage tank 35. Therefore, by controlling the space 35a to be in a state suitable for generating fog, fog can be generated reliably and stably.
[0022]
Note that, in FIG. 1 described above, in the present example, a configuration is adopted in which a mist-like coolant is supplied to each of the return channels 25 between the stages. Therefore, in the compressor 12, the temperature rise of the compressed gas is suppressed for each stage, and the compression power is reduced for each stage. Note that the present invention is not limited to a configuration in which the cooling liquid is supplied to all of the return channels 25 between the stages. Further, the position and number of the supply location of the mist-like cooling liquid in the return channel 25 are appropriately determined according to the type of the compressed gas and the compression conditions such as the compression ratio. As an example, by supplying the cooling liquid from a location (upstream position) as far as possible from the impeller 21 at the subsequent stage in the return channel 25, the distance from the supply location of the mist to the impeller 21 at the next stage becomes longer, and the compressed gas is reduced. It is possible to more reliably evaporate the liquid (mist) before reaching the impeller 21.
[0023]
Further, in the compressor 12 of the present embodiment, a part of the gas flowing through the return channel 25 is taken into the liquid storage tank 35 to supply the mist, that is, the mist of the mist is made using the dynamic pressure of the gas flow in the return channel 25. Because of the supply configuration, there is an advantage that motive energy for mist supply is reduced or eliminated. The method for supplying the fog is not limited to this method, and another method may be used.
[0024]
FIGS. 3 and 4 are diagrams illustrating another configuration example of the fog supply unit 32. FIG.
The mist supply unit 32a shown in FIG. 3 is for guiding the mist from the liquid storage tank 35 to the return channel 25 by reducing the pressure of the mist supply position in the return channel 25. That is, in the fog supply unit 32a, the discharge port 42a of the discharge pipe 42 for supplying the fog is disposed in the low-pressure part 25a of the return channel 25. The low-pressure portion 25 a can be formed, for example, by narrowing a part of the flow channel of the return channel 25 or providing a bypass flow channel having a small flow channel cross-sectional area with respect to the return channel 25. Alternatively, a low pressure region formed on the back surface of the object provided in the return channel 25 may be used. In this configuration, as compared with the configuration shown in FIG. 2, the configuration is simplified, such as omitting a gas introduction pipe for guiding gas to the liquid storage tank 35.
[0025]
Further, the fog supply unit 32b shown in FIG. 4 is configured to include a power source 46 such as a pump for supplying fog. That is, in the mist supply unit 32 b, for example, the mist is supplied from the liquid storage tank 35 to the return channel 25 by increasing the pressure of the internal space of the liquid storage tank 35 by the power source 46. In this configuration, since a power source for fog supply is provided, it is easy to control conditions related to fog supply such as a supply amount.
[0026]
Here, the compressor 12 is preferably applied not only when the static pressure of the flow path between the stages (such as the return channel 25) is positive with respect to the atmospheric pressure but also when the static pressure is negative. . When the static pressure of the flow path is a negative pressure with respect to the atmospheric pressure, there is an advantage that the pressure of the liquid supply source can be reduced and the liquid (mist) can be easily transported.
[0027]
In the compressor 12, the cooling liquid may be a liquefied compressed gas. In this case, the occurrence of inconvenience due to the mixture of the gas and the liquid (mist), such as generation of impurities due to a chemical reaction, for example, is suppressed. In this case, the compressor 12 can be preferably applied to a heat pump.
[0028]
A heat pump is a device that pumps heat from a low-temperature object and applies heat to a high-temperature object by a cycle including evaporation, compression, condensation, and expansion steps. Since the energy use efficiency is relatively high, it is widely used in heat utilization devices such as air conditioners and refrigeration devices having a cooling / heating function.
[0029]
FIG. 5 is a diagram schematically showing an embodiment in which the heat pump of the present invention is applied to an air conditioner. The air conditioner 110 has a function of cooling and heating indoor air, and includes a heat pump 114 including an evaporator 111, a compressor 112, and a condenser 113. In this example, the condenser 113 includes a cooler 116 that further includes a cooling fan and a heat exchanger for further cooling the condensed liquid.
[0030]
In this embodiment, the multi-stage compressor shown in FIGS. 1 and 2 is used as the compressor 112. That is, the compressor 112 is composed of a four-stage centrifugal compressor, and the cooling liquid supply device 30 supplies the mist-like cooling liquid to the flow path (return channel 25) between the respective stages. The cooling liquid is a gas flowing in the compressor 112, that is, a liquefied product of the refrigerant gas (refrigerant liquid), and is a part of the refrigerant liquid cooled and condensed in the condenser 113. More specifically, a part of the refrigerant liquid condensed in the condenser 113 and cooled by the cooler 116 is transported to the liquid storage tank 35 (see FIG. 2) of the cooling liquid supply device 30 by the pump 116a and cooled. Used as a liquid.
[0031]
In the heat pump 114, the refrigerant liquid in the evaporator 111 evaporates due to heat absorbed from the surroundings. Heat is supplied from the room during cooling and from the atmosphere during heating. The evaporated refrigerant gas (vapor) is compressed by the compressor 112 and discharged as a high-temperature and high-pressure gas. The discharged refrigerant gas is cooled and condensed by releasing heat to the surroundings in the condenser 113. Heat is released to the atmosphere during cooling, and is released indoors during heating. The refrigerant liquid that has exited the condenser 113 decreases in pressure and temperature via the expansion valve 115 and returns to the evaporator 111 again.
[0032]
In the heat pump 114, a part of the refrigerant liquid cooled and condensed in the condenser 113 (and the cooler 116) is sent to the cooling liquid supply device 30, where it is turned into mist and the compressed gas flow path of the compressor 112 is changed. 25. As the mist evaporates in the flow path 25, the compressed gas is cooled by the latent heat of evaporation.
[0033]
Examples of the refrigerant for the heat pump include water (H ₂ O) in addition to various known refrigerants such as a CFC-based refrigerant and ammonia. Since water has a large latent heat of vaporization, a theoretically high coefficient of performance (COP) is expected (about 1.5 times that of CFCs). Water refrigerants also have many environmental advantages (zero ozone depletion potential, zero global warming potential, etc.). However, since water has a large change in saturation pressure, compression at a high compression ratio (about three times or more of CFC) is required for use in a heat pump.
[0034]
Since the heat pump 114 of the present example includes the multi-stage compressor shown in FIGS. 1 and 2, it is possible to increase the compression ratio. Further, as described above, since the compressed gas is effectively cooled by the mist-like cooling liquid, the compression power is reduced. Therefore, the heat pump 114 of the present example can preferably cope with a refrigerant requiring a high compression ratio, such as water, by highly efficient compression. In addition, reduction of the compression power is advantageous also for downsizing of the compressor.
[0035]
As an example, in a water-refrigerant heat pump, the steam at the inlet of the compressor has a temperature of 5 ° C. and a pressure of 0.009 ata, and the steam at the outlet of the compressor has a temperature of 89 ° C. and 0.09 ata. It is. That is, the pressure in the flow path at both the inlet and the outlet of the compressor is negative with respect to the atmospheric pressure, and the compression ratio of the compressor needs to be about 10.
[0036]
In this water-refrigerant heat pump, the above-described mist-like cooling liquid (water) is supplied to a four-stage compressor at a mass flow rate with respect to steam flowing through the compressor in flow paths (three places) between the stages. When a total of about 10% of the cooling liquid (water) is added, a trial calculation shows that about 20% of the compression power is reduced.
[0037]
As described above, the heat pump can be applied to an air conditioner having at least one function of cooling, heating, dehumidification, and humidification. In addition, various devices that exchange heat with a heat source, such as a cooling device (such as a heat sink), a heating device (such as a floor heating device), a hot water supply device, a freezing device, a dehydrating device, a heat storage device, a snow melting device, and a drying device. It can be applied to various heat utilization devices (including plants and systems). In these heat utilization devices, high energy efficiency can be obtained by using the heat pump of the present invention. Further, by using water as the refrigerant of the heat pump, various environmental advantages can be obtained while improving energy efficiency.
[0038]
As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but it is needless to say that the present invention is not limited to such examples. The shapes, combinations, and the like of the constituent members shown in the above-described examples are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention.
[0039]
【The invention's effect】
As described above, according to the multi-stage compressor of the present invention, since the mist-like liquid easily evaporates in the flow passage between the stages, the compressed gas can be effectively cooled by the latent heat of evaporation.
Further, according to the heat pump of the present invention, the compression power is reduced by effectively cooling the compressed gas. Therefore, energy efficiency can be improved. Moreover, the heat pump of the present invention can preferably cope with a refrigerant that requires a high compression ratio, such as water, by highly efficient compression.
Further, according to the heat utilization device of the present invention, the use of the heat pump can improve energy efficiency.
[Brief description of the drawings]
FIG. 1 is a view schematically showing an embodiment of a multi-stage compressor according to the present invention.
FIG. 2 is a diagram conceptually showing a configuration of a cooling liquid supply device.
FIG. 3 is a diagram illustrating another configuration example of the fog supply unit.
FIG. 4 is a diagram illustrating another configuration example of the fog supply unit.
FIG. 5 is a diagram schematically showing an embodiment in which the heat pump of the present invention is applied to an air conditioner.
[Explanation of symbols]
12: compressor (multistage compressor), 20: rotating shaft, 21: impeller, 25: return channel (flow path), 31: atomizing unit, 32: fog supply unit, 35: liquid storage tank, 35a: liquid storage Internal space of the tank, 36: atomizer, 41: gas introduction pipe, 41b: introduction port, 42: discharge pipe, 110: air conditioner, 111: evaporator, 112: compressor, 113: condenser, 114 ... Heat pump, 115: expansion valve, 116: cooler.

Claims (7)

In a multi-stage compressor that compresses gas in multiple stages,
An atomizing unit that generates mist from the liquid in a space different from the flow path between the stages,
A multistage compressor having a mist supply unit for supplying the mist from the space to the flow path. 2. The multi-stage compressor according to claim 1, wherein the supply unit supplies the mist from the space to the flow channel using a dynamic pressure of the gas in the flow channel. 3. The multi-stage compressor according to claim 1 or 2, wherein the static pressure of the flow path is a negative pressure with respect to the atmospheric pressure. The multi-stage compressor according to any one of claims 1 to 3, wherein the liquid is a liquefied substance of the gas. A heat pump comprising the multi-stage compressor according to any one of claims 1 to 4. The heat pump according to claim 5, wherein the refrigerant is water. A heat utilization device that exchanges heat with a heat source,
A heat utilization device comprising the heat pump according to any one of claims 1 to 6.

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