KR20250040778A - Heat pump using oil free centrifugal compressor and steam generating system using the same - Google Patents

Abstract

The present invention comprises: a double-suction centrifugal compressor which compresses refrigerant compressed at a low stage once more at a high stage; a condenser which condenses the refrigerant so that heat is released from the refrigerant passing through the double-suction centrifugal compressor; a first expansion valve which expands the refrigerant passing through the condenser; a refrigerant flash tank which separates the refrigerant passing through the first expansion valve into a gas phase and a liquid phase; a second expansion valve which expands the liquid refrigerant discharged from the refrigerant flash tank; an evaporator which absorbs heat energy from a heat source and evaporates the refrigerant passing through the second expansion valve; an internal heat exchanger which is installed between the refrigerant flash tank and the second expansion valve so that heat exchange occurs between the refrigerant before passing through the evaporator and flowing into the double-suction centrifugal compressor and the refrigerant discharged in a liquid phase from the refrigerant flash tank; and a heat exchanger which is branched between the internal heat exchanger and the second expansion valve and discharges a portion of the refrigerant as a cooling refrigerant into the interior of the double-suction centrifugal compressor. A heat pump using a double-suction centrifugal compressor is disclosed, which includes a cooling path for guiding the cooling refrigerant to be injected, and a return path for guiding the cooling refrigerant so that the cooling refrigerant cools the inside of the double-suction centrifugal compressor and then is discharged to join the refrigerant flowing into the double-suction centrifugal compressor from the internal heat exchanger at the low-stage inlet side.

Description

Heat pump using a double suction centrifugal compressor and a heat pump type steam generation system including the same {HEAT PUMP USING OIL FREE CENTRIFUGAL COMPRESSOR AND STEAM GENERATING SYSTEM USING THE SAME}

The present invention relates to a heat pump using a double-suction centrifugal compressor and a heat pump-type steam generation system including the same, and more specifically, to a heat pump configured to effectively cool a double-suction centrifugal compressor in order to stably generate high-temperature steam, and a steam generation system using the same.

In general, a heat pump compresses a low-temperature, low-pressure gaseous refrigerant in a compressor to high-temperature, high-pressure refrigerant, releases heat to the outside through a condenser, then expands the condensed liquid refrigerant to lower the pressure and temperature, and absorbs heat from the outside in the evaporator and supplies it back to the compressor in a gaseous state, forming a cycle. This heat pump can utilize wasted heat such as waste heat or unused heat, and can be electrified in line with the decarbonization policy, so it is emerging as one of the important technologies for future energy strategies. In particular, the demand for ultra-high-temperature steam is high in industrial sites, and the demand for heat pumps that produce ultra-high-temperature steam is also expected to increase in the future.

However, since it is recommended to use low GWP, i.e. environmentally friendly refrigerants, as refrigerants used in heat pumps, ultra-high temperature steam generation heat pumps must be able to generate ultra-high temperature steam while using environmentally friendly refrigerants. Accordingly, the performance of the compressor that compresses the refrigerant is becoming very important.

The double-suction centrifugal compressor equipped with magnetic bearings is attracting attention as a compressor suitable for heat pumps that generate ultra-high temperature steam. The double-suction centrifugal compressor equipped with magnetic bearings has a simple structure, is easy to compress multi-stage refrigerant, and does not use lubricating oil, so there are no problems related to lubricating oil.

However, in the case of heat pumps that generate ultra-high temperature steam of 150°C or higher, the operating conditions are extreme and the compressor may overheat, and if the compressor overheating continues, the life of the compressor may be shortened and the heat pump efficiency may decrease. Therefore, in order to operate the ultra-high temperature heat pump stably for a long time, an effective means of preventing the compressor from overheating is required.

An object of the present invention is to provide a heat pump-type steam generation system including a heat pump that effectively cools a double-suction centrifugal compressor and a steam generation device that generates steam through heat exchange with the heat pump.

The present invention comprises: a double-suction centrifugal compressor which compresses refrigerant compressed at a low stage once more at a high stage; a condenser which condenses the refrigerant so that heat is released from the refrigerant passing through the double-suction centrifugal compressor; a first expansion valve which expands the refrigerant passing through the condenser; a refrigerant flash tank which separates the refrigerant passing through the first expansion valve into a gas phase and a liquid phase; a second expansion valve which expands the liquid refrigerant discharged from the refrigerant flash tank; an evaporator which absorbs heat energy from a heat source and evaporates the refrigerant passing through the second expansion valve; an internal heat exchanger which is installed between the refrigerant flash tank and the second expansion valve so that heat exchange occurs between the refrigerant before passing through the evaporator and flowing into the double-suction centrifugal compressor and the refrigerant discharged in a liquid phase from the refrigerant flash tank; and a heat exchanger which is branched between the internal heat exchanger and the second expansion valve and discharges a portion of the refrigerant as a cooling refrigerant into the interior of the double-suction centrifugal compressor. A heat pump using a double-suction centrifugal compressor is disclosed, which includes a cooling path for guiding the cooling refrigerant to be injected, and a return path for guiding the cooling refrigerant so that the cooling refrigerant cools the inside of the double-suction centrifugal compressor and then is discharged to join the refrigerant flowing into the double-suction centrifugal compressor from the internal heat exchanger at the low-stage inlet side.

The above heat pump further includes a cooling channel valve installed on the cooling channel and a control unit that controls the opening of the cooling channel valve so that the flow rate of the cooling refrigerant is adjusted, and the control unit can control the flow rate of the refrigerant mixed by the joining so that the refrigerant is within a preset superheating range.

The above heat pump further includes a temperature sensor for measuring the temperature of the refrigerant sucked into the double-suction centrifugal compressor, and a pressure sensor for measuring the pressure of the refrigerant sucked into the double-suction centrifugal compressor, and the control unit receives measurement information from the temperature sensor and the pressure sensor to detect the superheating degree of the mixed refrigerant, and can determine whether the superheating degree of the mixed refrigerant has reached the preset superheating degree.

The above-described double-suction centrifugal compressor includes a motor that provides power for compressing the refrigerant, an inlet port that is opened to inject the cooling refrigerant toward the inside where the motor is located, and a discharge port that is opened to discharge the cooling refrigerant that has cooled the motor, and the inlet port and the discharge port can be respectively provided on both sides with the stator of the motor interposed therebetween.

The above-mentioned double-suction centrifugal compressor may further include a spray nozzle connected to the cooling path and installed in the injection unit to lower the temperature of the cooling refrigerant and spray it.

The above-described double-suction centrifugal compressor further includes a magnetic bearing supporting a shaft of the motor, the magnetic bearing including two radial bearings arranged opposite each other with the motor therebetween, and a thrust bearing arranged between a high-stage radial bearing among the two radial bearings and the motor, the injection portion may be located on one side of the stator corresponding to the high-stage side, and the discharge portion may be located on the other side of the stator corresponding to the low-stage side.

The above-described double-suction centrifugal compressor may further include an impeller that causes the refrigerant to flow, the impeller being installed on each of the low-stage inlet side and the high-stage inlet side, and the injection portion may include a first inlet located between the high-stage side radial bearing and the high-stage side impeller, and a second inlet located on a side surface of the thrust bearing.

The above-mentioned double-suction centrifugal compressor further includes a cooling jacket surrounding the outer surface of the housing, and the cooling jacket may be provided with a supply port for supplying cooling water and a discharge port for discharging cooling water.

The above-described double-suction centrifugal compressor may further include a connecting passage guiding the refrigerant discharged from the low stage to be introduced into the high stage, and the heat pump may further include an injection passage connecting the refrigerant flash tank and the connecting passage so that the refrigerant discharged as a gas from the refrigerant flash tank is mixed with the refrigerant before being introduced into the high stage of the double-suction centrifugal compressor.

Meanwhile, the present invention discloses a heat pump-type steam generation system including a heat pump and a steam generator which generates steam through heat exchange with the condenser of the heat pump to transfer heat absorbed from a low-temperature heat source to a high-temperature heat source, wherein the steam generator includes a steam flash tank which generates steam using heat released from the condenser through circulating water, a circulation path which guides the circulating water to circulate between the condenser and the steam flash tank, a circulating water discharge path which is connected to one of the circulating water path and the steam flash tank so as to discharge a portion of the circulating water, and a circulating water supply path which is connected to one of the circulating water path and the steam flash tank so as to replenish water to the circulating water.

At this time, the refrigerant may be R1336mzz(Z) and may generate vapor of 150°C or higher.

Meanwhile, the present invention relates to a cooling method for a double-suction centrifugal compressor equipped in a heat pump configured to transfer heat absorbed from a low-temperature heat source to a high-temperature heat source, the method comprising: a step of detecting the degree of overheating of a motor equipped in the double-suction centrifugal compressor; a step of calculating the required flow rate of a cooling refrigerant based on the degree of overheating of the motor; and a step of controlling the flow rate of a cooling refrigerant flowing in a cooling path so that the cooling refrigerant is injected into the interior of the double-suction centrifugal compressor in an amount equivalent to the required flow rate of the cooling refrigerant, and is characterized in that a portion of the refrigerant flowing from the internal heat exchanger to the second expansion valve is used as the cooling refrigerant.

The heat pump according to the present invention can maximize cooling efficiency by using a portion of a refrigerant suitable for use in cooling a double-suction centrifugal compressor as a cooling refrigerant, and its configuration for this purpose is not complicated, so that the manufacturing cost is not high.

In addition, the heat pump according to the present invention can increase the operating efficiency by allowing the refrigerant, which has cooled the double-suction centrifugal compressor, to be added to the refrigerant flowing into the low-stage inlet of the double-suction centrifugal compressor, thereby making it easier for the refrigerant to reach the target superheat level.

In addition, the heat pump according to the present invention can achieve the effect of doubly cooling the double-suction centrifugal compressor by cooling the interior of the double-suction centrifugal compressor surrounding the motor and magnetic bearings using a cooling refrigerant and cooling the exterior of the double-suction centrifugal compressor using cooling water.

Furthermore, the steam generation system according to the present invention can operate stably and effectively generate ultra-high temperature steam while using an eco-friendly refrigerant by utilizing such a heat pump.

Figure 1 is a conceptual diagram schematically illustrating a heat pump according to the present invention.
FIG. 2 is a drawing schematically illustrating a cross-section of a double-suction centrifugal compressor included in a heat pump according to FIG. 1.
Figure 3 is a conceptual diagram schematically illustrating a steam generation system using a heat pump according to Figure 1.
FIG. 4 is a conceptual diagram schematically illustrating various embodiments of a steam generating device according to the present invention.
Figure 5 is a flow chart showing a cooling method of a double-suction centrifugal compressor equipped in a heat pump according to the present invention.

Hereinafter, embodiments disclosed in the present specification will be described in detail with reference to the attached drawings. In this specification, the same reference numerals are given to identical or similar components even in different embodiments, and redundant descriptions thereof will be omitted. The suffixes "module," "unit," and "part" used for components in the following description are assigned or used interchangeably only for the convenience of writing the specification, and do not have distinct meanings or roles in themselves. In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in the present specification, and the technical ideas disclosed in the present specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise.

When it is stated herein that a component is "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components in between. On the other hand, when it is stated that a component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

Furthermore, it should be understood that terms such as "includes" or "have" are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, and do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

The present invention relates to a heat pump configured to effectively cool a double-suction centrifugal compressor to stably generate high-temperature steam, a steam generating device that generates steam through heat exchange with the heat pump, and a steam generating system including these.

The heat pump (100) according to the present invention can form a cycle that circulates a refrigerant to transfer heat absorbed from a low-temperature heat source to a high-temperature heat source. The structure of this heat pump (100) is described with reference to Fig. 1. Fig. 1 is a conceptual diagram schematically illustrating a heat pump (100) according to the present invention.

Referring to FIG. 1, a heat pump (100) according to the present invention includes a double-suction centrifugal compressor (110), a condenser (120), a first expansion valve (130), a refrigerant flash tank (140), a second expansion valve (150), an evaporator (160), and an internal heat exchanger (170).

The double-suction centrifugal compressor (110) may include a plurality of stages. In the present specification, the double-suction centrifugal compressor (110) is configured to enable two-stage compression. That is, the double-suction centrifugal compressor (110) may include a low-stage compression unit (hereinafter, referred to as a 'low stage') and a high-stage compression unit (hereinafter, referred to as a 'high stage'). Accordingly, the double-suction centrifugal compressor (110) may suck in a refrigerant at a low stage, compress it, and send the compressed refrigerant to a high stage to compress it once more. The refrigerant compressed at a high stage has a relatively higher pressure than the refrigerant compressed at a low stage.

A heat pump (100) may be equipped with a plurality of such double-suction centrifugal compressors (110). For example, the heat pump (100) may be equipped with two double-suction centrifugal compressors (110) in series, in which case the heat pump (100) performs a total of four stages of refrigerant compression.

The double suction centrifugal compressor (110) will be described in more detail later.

The condenser (120) condenses the refrigerant so that heat is released from the refrigerant that has passed through the double-suction centrifugal compressor (110).

Specifically, refrigerant compressed in a double-suction centrifugal compressor (110) and brought into a high-temperature and high-pressure state is introduced into the condenser (120), and the refrigerant can release heat while being condensed within the condenser (120). This condenser (120) may also be called a 'cooler' or a 'heat exchanger'. The refrigerant, whose temperature is lowered in the condenser (120), is sent to the first expansion valve (130).

The first expansion valve (130) expands the refrigerant so that the pressure of the refrigerant, which has become low temperature after passing through the condenser (120), is lowered. The first expansion valve (130) can also control the flow rate of the refrigerant passing through it.

The refrigerant flash tank (140) separates the refrigerant that has passed through the first expansion valve (130) into gas phase and liquid phase. This refrigerant flash tank (140) may also be called a 'separator' or a 'gas-liquid separator'. The liquid refrigerant in the refrigerant flash tank (140) is sent to the second expansion valve (150).

The second expansion valve (150) expands the refrigerant discharged in a liquid state from the refrigerant flash tank (140). The pressure of the refrigerant passing through the second expansion valve (150) becomes lower than the pressure of the refrigerant passing through the first expansion valve (130). The second expansion valve (150) can also control the flow rate of the refrigerant passing through.

The evaporator (160) absorbs heat energy from a heat source and evaporates the refrigerant passing through the second expansion valve (150). Accordingly, the refrigerant in a liquid state absorbs heat energy from the heat source and becomes a gaseous state.

The refrigerant passing through the evaporator (160) may be configured to flow directly into the double-suction centrifugal compressor (110), but in the present specification, the heat pump (100) is configured to have an internal heat exchanger (170) so that the refrigerant passing through the evaporator (160) passes through the internal heat exchanger (170) before flowing into the double-suction centrifugal compressor (110). At the same time, the heat pump (100) is configured so that the refrigerant passing through the refrigerant flash tank (140) passes through the internal heat exchanger (170) before being sent to the second expansion valve (150).

Referring to FIG. 1, an internal heat exchanger (170) is interposed between a refrigerant flash tank (140) and a second expansion valve (150), and at the same time, between an evaporator (160) and a double-suction centrifugal compressor (110).

Here, the space between the refrigerant flash tank (140) and the second expansion valve (150) or between the evaporator (160) and the double-suction centrifugal compressor (110) means the middle in the order in which the refrigerant passes, and may not mean a physical arrangement relationship.

In terms of the flow of refrigerant, liquid refrigerant is discharged from the refrigerant flash tank (140) and flows into the internal heat exchanger (170), discharged from the internal heat exchanger (170) and sent to the second expansion valve (150), then passes through the evaporator (160) and flows back into the refrigerant flash tank (140). Thereafter, the refrigerant discharged from the refrigerant flash tank (140) flows into the double-suction centrifugal compressor (110).

Accordingly, in the internal heat exchanger (170), heat exchange is performed between the refrigerant that has passed through the evaporator (160) and entered the double-suction centrifugal compressor (110) and the refrigerant discharged in a liquid state from the refrigerant flash tank (140).

At this time, the internal heat exchanger (170) can be configured so that the refrigerant flowing in from the evaporator (160) and the refrigerant flowing in from the refrigerant flash tank (140) move separately from each other.

The energy efficiency of the heat pump (100) can be further improved through the introduction of such an internal heat exchanger (170).

In this way, the heat pump (100) is configured to circulate a cycle in which the refrigerant sequentially passes through a double-suction centrifugal compressor (110), a condenser (120), a first expansion valve (130), a refrigerant flash tank (140), a second expansion valve (150), an internal heat exchanger (170), and an evaporator (160), and then passes through the internal heat exchanger (170) and is introduced into the double-suction centrifugal compressor (110). Accordingly, the heat pump (100) may further include a path connecting them.

Referring to FIG. 1, the heat pump (100) has a first flow path (101) connecting a double-suction centrifugal compressor (110) and a condenser (120), a second flow path (102) connecting a condenser (120) and a first expansion valve (130), a third flow path (103) connecting a first expansion valve (130) and a refrigerant flash tank (140), a fourth flow path (104) connecting a refrigerant flash tank (140) and an internal heat exchanger (170), a fifth flow path (105) connecting an internal heat exchanger (170) and a second expansion valve (150), a sixth flow path (106) connecting a second expansion valve (150) and an evaporator (160), a seventh flow path (107) connecting an evaporator (160) and an internal heat exchanger (170), and a seventh flow path (107) connecting an internal heat exchanger (170) and a double-suction centrifugal compressor (110). It includes the 8th euro (108). At this time, the 8th euro (108) can be connected to the low stage inlet of the double suction centrifugal compressor (110), and the 1st euro (101) can be connected to the high stage outlet of the double suction centrifugal compressor (110).

Furthermore, the heat pump (100) further includes a cooling path (1051) and a return path (1052).

Referring to FIG. 1, the cooling path (1051) branches off between the internal heat exchanger (170) and the second expansion valve (150) to guide a portion of the refrigerant to be injected into the interior of the double-suction centrifugal compressor (110) as a cooling refrigerant. That is, the cooling path (1051) branches off at the fifth path (105). The refrigerant passing through the fifth path (105) becomes a state in which its temperature is lowered as it passes through the internal heat exchanger (170), which may be the most suitable state for use as a cooling refrigerant. Since the refrigerant may become an unsuitable state for use as a cooling refrigerant if it passes through the second expansion valve (150), it is most preferable that the cooling path (1051) branches off at the fifth path (105) before passing through the second expansion valve (150).

The cooling path (1051) branched from the fifth path (105) is connected to a double-suction centrifugal compressor (110). At this time, the cooling refrigerant flowing along the cooling path (1051) is injected into the double-suction centrifugal compressor (110) and is injected into a space separated from the refrigerant flowing into the double-suction centrifugal compressor (110) along the eighth path (108).

Here, the refrigerant for cooling is a part of the refrigerant branched off from the refrigerant flowing between the internal heat exchanger (170) and the second expansion valve (150) as described above. This distinction is made only for convenience of explanation, and does not mean that the refrigerant and the refrigerant for cooling are different substances.

Meanwhile, the return path (1052) guides the cooling refrigerant so that the cooling refrigerant, which has cooled the interior of the double-suction centrifugal compressor (110) and is then discharged, joins with the refrigerant flowing into the double-suction centrifugal compressor (110) from the internal heat exchanger (170) at the low-stage inlet side.

Referring to Fig. 1, the return path (1052) connects the double-suction centrifugal compressor (110) and the eighth path (108). Accordingly, the cooling refrigerant can be cooled inside the double-suction centrifugal compressor (110) and then rejoined (returned) to the refrigerant through the return path (1052).

The return path (1052) is connected to the double-suction centrifugal compressor (110) on one side and to the eighth path (108) on the other side, but the return path (1052) is not limited to being connected to a path other than the eighth path (108). However, it is preferable that the return path (1052) is connected to a position close to the low-stage inlet side of the double-suction centrifugal compressor (110) even in the eighth path (108). The reason for this is that when the cooling refrigerant is combined with the refrigerant flowing into the low stage of the double-suction centrifugal compressor (110), it is advantageous for the refrigerant flowing into the low stage of the double-suction centrifugal compressor (110) to reach the target superheating degree. This is an effect achieved because the temperature of the cooling refrigerant rises after cooling the inside of the double-suction centrifugal compressor (110). That is, the refrigerant mixed with the cooling refrigerant can be in a state where it is easier to reach the target superheat than the unmixed refrigerant. This means that the refrigerant can be made to reach the target superheat with less energy, and it can be said that the heat pump (100) operates more efficiently.

Here, the target superheat is the superheat required for the refrigerant flowing into the low stage of the double-suction centrifugal compressor (110), and may be set to a specific value or set as a range.

For measuring superheat, the heat pump (100) may further include at least one temperature sensor or pressure sensor. Matters related to measuring superheat will be described in detail later.

Meanwhile, the heat pump (100) may further include a cooling flow valve (180) and a control unit.

The cooling path valve (180) is installed on the cooling path (1051) and can be controlled by a control unit.

The control unit can control the opening of the cooling path valve (180) so that the flow rate of the cooling refrigerant flowing along the cooling path (1051), i.e. flowing into the double-suction centrifugal compressor (110), is controlled.

The control unit can further open the cooling flow valve (180) if it is desired to increase the amount of refrigerant for cooling. Conversely, the control unit can further close the cooling flow valve (180) if it is desired to decrease the amount of refrigerant for cooling.

The opening of the cooling path valve (180) does not necessarily mean complete opening, and may include partial opening to the extent that at least some of the cooling refrigerant can flow along the cooling path (1051). The closing of the cooling path valve (180) also does not necessarily mean complete closing, and may include partial closing to the extent that at least some of the cooling refrigerant can flow along the cooling path (1051).

The control unit will be described in more detail later.

As examined above, the heat pump (100) according to the present invention can maximize cooling efficiency by using a portion of the refrigerant that is suitable for use in cooling a double-suction centrifugal compressor (110) as a cooling refrigerant, and the configuration for this is not complicated, so the manufacturing cost is not high.

The heat pump (100) can increase operating efficiency by allowing the refrigerant that has cooled the double-suction centrifugal compressor (110) to be added to the refrigerant flowing into the low-stage inlet of the double-suction centrifugal compressor (110), thereby making it easier for the refrigerant to reach the target superheat level.

Meanwhile, the heat pump (100) can use a refrigerant of the HFOs (Hydrofluoroolefins) or HCFO (Hydrochlorofluoroolefin) series, which is a low-GWP (global warming potential), as a working fluid. Specifically, the heat pump (100) can use refrigerants such as R1336mzz (Z), R1224yd (Z), and R1233zd (E), and among these, it is preferable to use R1336mzz (Z) as a working fluid. When R1336mzz (Z) is used as a working fluid, products such as Opteon MZ or Opteon 1100 can be used.

In addition, the heat pump (100) can use waste heat, geothermal heat, air heat, or unused heat as a heat source, and for this purpose, it can also include a component for recovering heat (e.g., a heat source recovery device, a heat source supply device, etc.). However, in this specification, the component for recovering heat is not related to the problem to be solved by the present invention, so a description thereof will be omitted.

Hereinafter, a double-suction centrifugal compressor (110) will be described with reference to Fig. 2. Fig. 2 is a drawing schematically illustrating a cross-section of a double-suction centrifugal compressor (110) included in a heat pump (100) according to Fig. 1.

In Fig. 2, the low stage (111) of the double suction centrifugal compressor (110) corresponds to the left, and the high stage (112) corresponds to the right. However, according to another embodiment, the double suction centrifugal compressor (110) may have a different shape and configuration from those of Fig. 2, and the number of configurations is also not limited to Fig. 2.

A double suction centrifugal compressor (110) may include a motor (113), an injection unit (114), and a discharge unit (115).

First, the motor (113) provides power to compress the refrigerant. The motor (113) may include a cylindrical rotor (113a) and a stator (113b) formed by surrounding the outer surface of the rotor (113a).

The rotor (113a) of the motor (113) includes a shaft formed by extending longitudinally from both ends, and a magnetic bearing (117) to be described later penetrates the shaft to support the shaft so that the rotor (113a) can rotate in the air.

The double-suction centrifugal compressor (110) may further include a housing (110a) to protect the motor (113) and the magnetic bearing (117). The housing (110a) of the double-suction centrifugal compressor (110) forms the overall outer shape of the double-suction centrifugal compressor (110) and may be configured as an integral or divided form. If the housing (110a) is divided, the double-suction centrifugal compressor (110) may additionally be provided with a means for fastening the divided housings (110a).

This housing (110a) can form an internal space surrounding a motor (113) and a magnetic bearing (117). And a part of the internal space can be communicated with the outside of the double-suction centrifugal compressor (110) through an injection part (114).

The injection part (114) is formed in the housing (110a) and is opened so that a cooling refrigerant is injected toward the interior where the motor (113) is located. Here, the interior where the motor (113) is located means the internal space surrounding the motor (113) and the magnetic bearing (117).

The discharge portion (115) is formed in the housing (110a) and is opened to discharge the cooling refrigerant that cools the motor (113). The discharge portion (115) may also allow a portion of the internal space to communicate with the outside.

These injection parts (114) and discharge parts (115) can be provided on both sides with the stator (113b) of the motor (113) interposed therebetween.

Referring to FIG. 2, the injection part (114) may be located on one side of the stator (113b) corresponding to the high stage (112) side, and the discharge part (115) may be located on the other side of the stator (113b) corresponding to the low stage (111) side.

The double suction centrifugal compressor (110) may further include a spray nozzle (116).

A spray nozzle (116) is installed in the injection portion (114) to lower the temperature of the cooling refrigerant and spray the cooling refrigerant. The sprayed cooling refrigerant has a lower temperature than when flowing through the cooling path (1051), which makes it more advantageous for cooling the double-suction centrifugal compressor (110).

In addition, the spray angle can be widened by the spray nozzle (116) so that the refrigerant for cooling can be evenly distributed inside the double-suction centrifugal compressor (110).

The spray nozzle (116) is connected to the cooling path (1051), and there is no limitation on the connection method.

The cooling refrigerant sprayed by the spray nozzle (116) is sprayed into the internal space surrounding the motor (113) and the magnetic bearing (117), and passes through the gap between the rotor (113a) and the stator (113b), the gap between the stator (113b) and the inner wall of the double-suction centrifugal compressor (110), etc., thereby lowering the temperature of the overheated motor (113).

The double-suction centrifugal compressor (110) may further include a magnetic bearing (117) supporting the shaft of the motor (113). Here, the shaft of the motor (113) means the shaft of the rotor (113a). The motor (113) rotates around the shaft and transmits power, and the magnetic bearing (117) may support the motor (113) to rotate stably.

Referring to FIG. 2, the magnetic bearing (117) may include a radial bearing (117a) and a thrust bearing (117b). In the present specification, the magnetic bearing (117) includes two radial bearings (117a) and one thrust bearing (117b), but the number is not limited thereto.

The thrust bearing (117b) may be arranged between the radial bearing (117a) on the high stage (112) side among the two radial bearings (117a) and the stator (113b) of the motor (113). However, the thrust bearing (117b) may be located anywhere inside the double-suction centrifugal compressor (110) as long as it is on the shaft of the double-suction centrifugal compressor (110).

Meanwhile, the double-suction centrifugal compressor (110) may further include an impeller (118) that causes the flow of refrigerant.

The impeller (118) is used to increase the pressure and flow of the refrigerant and may include a plurality of blades extending radially from a center portion.

The impeller (118) is located inside the housing (110a) and can be installed on each of the low-stage inlet (111a) side and the high-stage inlet (112a) side.

Referring to Fig. 2, a low-stage (111) side impeller (118a) is installed on the low-stage inlet (111a) side, and a high-stage (112) side impeller (118b) is installed on the high-stage inlet (112a) side. The low-stage (111) side impeller (118a) and the high-stage (112) side impeller (118b) are arranged to face each other on both sides of a double-suction centrifugal compressor (110) so as to suck refrigerant from both sides of the double-suction centrifugal compressor (110).

The impeller (118a) on the low stage (111) side and the impeller (118b) on the high stage (112) side may be the same or different in size and shape.

The injection unit (114) and the discharge unit (115) may each be provided in multiple numbers. According to the embodiment of the present specification, two injection units (114) are provided. Accordingly, the injection unit (114) may include a first injection port (114a) and a second injection port (114b).

Referring to FIG. 2, the first inlet (114a) may be located between the radial bearing (117a) on the high stage (112) side and the impeller (118b) on the high stage (112) side, and the second inlet (114b) may be located on the side of the thrust bearing (117b).

To this end, the cooling channel (1051) connected to the injection unit (114) may be branched at one end to be connected to each of the first injection port (114a) and the second injection port (114b). At this time, the spray nozzle (116) may also include a first spray nozzle (116a) installed in the first injection port (114a) and a second spray nozzle (116b) installed in the second injection port (114b) according to the number of injection units (114). Here, the fact that the cooling channel (1051) is connected to the injection unit (114) is not structurally different from the fact that the cooling channel (1051) is connected to the spray nozzle (116).

The refrigerant for cooling injected into the first inlet (114a) can be sprayed into the first space (110aa) among the internal spaces surrounding the motor (113) and the magnetic bearing (117). Referring to FIG. 2, the first space (110aa) can be formed by the housing (110a) of the double-suction centrifugal compressor (110), the high-stage (112)-side radial bearing (117a), and the high-stage (112)-side impeller (118b). Accordingly, the refrigerant for cooling injected into the first inlet (114a) is configured to flow along the exposed surfaces of the high-stage (112)-side radial bearing (117a), the thrust bearing (117b), the rotor (113a), the stator (113b), and the low-stage (111)-side radial bearing (117a) and be discharged to the discharge portion (115).

Referring to FIG. 2, at least a portion of the cooling refrigerant injected into the first space (110aa) can move through a cooling refrigerant passage (110b) leading to the second space (110ab). The cooling refrigerant passage (110b) can be formed by penetrating the housing (110a). The second space (110ab) can be formed by the housing (110a) of the double-suction centrifugal compressor (110), the thrust bearing (117b), and the stator (113b). Accordingly, at least a portion of the cooling refrigerant injected into the first inlet (114a) is configured to flow along the exposed surfaces of the thrust bearing (117b), the rotor (113a), the stator (113b), and the low-stage (111)-side radial bearing (117a) and be discharged to the discharge portion (115).

Meanwhile, the cooling refrigerant injected into the second inlet (114b) may be sprayed into the third space (110ac) among the internal spaces surrounding the motor (113) and the magnetic bearing (117). Referring to FIG. 2, the third space (110ac) may be formed by the housing (110a) of the double-suction centrifugal compressor (110), the thrust bearing (117b), and the stator (113b). Accordingly, the cooling refrigerant injected into the second inlet (114b) is configured to flow along the exposed surfaces of the thrust bearing (117b), the rotor (113a), the stator (113b), and the low-stage (111)-side radial bearing (117a) and be discharged to the discharge portion (115).

Furthermore, the first inlet (114a) and the second inlet (114b) may be positioned at positions approximately 180 degrees apart from each other based on the rotation axis of the motor (113). The first inlet (114a) and the second inlet (114b) may help to effectively cool the motor (113) by increasing the area where the cooling refrigerant comes into contact with the motor (113). The cooling refrigerant may not only cool the motor (113), but may also cool the entire internal space of the double-suction centrifugal compressor (110), including the magnetic bearing (117).

The cooling refrigerant that cools the interior of the double-suction centrifugal compressor (110) including the motor (113) can be collected into a fourth space (110ad) connected to the discharge portion (115). The fourth space (110ad) can be formed by the housing (110a) of the double-suction centrifugal compressor (110), the low-stage (111) side radial bearing (117a), and the stator (113b).

Meanwhile, the internal space surrounding the motor (113) and the magnetic bearing (117) can be physically separated from the flow path of the refrigerant flowing in for compression. Accordingly, the refrigerant compressed in the double-suction centrifugal compressor (110) is not mixed with the refrigerant for cooling inside the double-suction centrifugal compressor (110).

Furthermore, the heat pump (100) may further include a cooling jacket (110c) that surrounds the outer surface of the housing (110a) of the double-suction centrifugal compressor (110).

Referring to FIG. 2, a cooling jacket (110c) can surround a portion of a housing (110a) of a double-suction centrifugal compressor (110).

Cooling water is supplied between the cooling jacket (110c) and the housing (110a) to cool the double-suction centrifugal compressor (110). To this end, the double-suction centrifugal compressor (110) may be provided with a cooling water passage (110d) through which the cooling water flows. For example, as shown in FIG. 2, a plurality of grooves may be formed at regular intervals along the outer surface of the housing (110a), and the cooling jacket (110c) may be formed to surround the outer surface of the housing (110a) including the plurality of grooves. Cooling water may flow through the cooling water passage (110d) formed by the plurality of grooves and the cooling jacket (110c). The cooling water flowing along the cooling water passage (110d) cools the double-suction centrifugal compressor (110).

As another example, the cooling jacket (110c) may be formed to wrap around the outer surface of the main body of the double-suction centrifugal compressor (110) at a predetermined interval.

A cooling jacket (110c) has holes formed to allow cooling water to enter and exit through a cooling water passage (110d), and a supply port (110e) for supplying cooling water and a discharge port (110f) for discharging cooling water can be installed corresponding to these holes.

In this way, the heat pump (100) according to the present invention cools the interior of the double-suction centrifugal compressor (110) surrounding the motor (113) and the magnetic bearing (117) using a cooling refrigerant, and cools the exterior of the double-suction centrifugal compressor (110) using cooling water, thereby achieving the effect of doubly cooling the double-suction centrifugal compressor (110).

Meanwhile, referring again to FIG. 1, the double-suction centrifugal compressor (110) may further include a connecting passage (1101) that guides the refrigerant discharged from the low stage (111) to flow into the high stage (112).

Referring to FIG. 2, one end of the connecting passage (1101) is connected to the outlet (111b) of the low stage (111), and the other end of the connecting passage (1101) is connected to the inlet (112a) of the high stage (112). Accordingly, the refrigerant can be introduced through the inlet (111a) of the low stage (111), compressed, discharged from the outlet (111b) of the low stage (111), and introduced into the inlet (112a) of the high stage (112). Thereafter, the refrigerant is compressed once more, discharged through the outlet (112b) of the high stage (112), and sent to the condenser (120).

Furthermore, the heat pump (100) may further include an injection path (109) connecting the refrigerant flash tank (140) and the connection path (1101).

The injection path (109) can guide the refrigerant discharged as a gas from the refrigerant flash tank (140) to be introduced into the connection path (1101). Accordingly, the refrigerant discharged as a gas from the refrigerant flash tank (140) can be mixed with the refrigerant discharged from the low stage (111) of the double-suction centrifugal compressor (110) before being introduced into the high stage (112).

Meanwhile, the present invention discloses a heat pump-type steam generation system (10, hereinafter referred to as 'steam generation system') that generates steam using such a heat pump (100).

Fig. 3 is a conceptual diagram schematically illustrating a steam generation system (10) using a heat pump (100) according to Fig. 1. Referring to Fig. 3, the steam generation system (10) includes a heat pump (100) and a steam generation device (200).

The steam generator (200) generates steam through heat exchange with the condenser (120) of the heat pump (100).

To this end, the steam generation device (200) includes a steam flash tank (210), a circulation path (220), a steam path (230), a circulation water discharge path (240), and a circulation water supply path (250).

The steam flash tank (210) can generate steam by using heat released from the condenser (120) via circulating water. Specifically, the steam flash tank (210) can generate steam by depressurizing circulating water that has been heated while passing through the condenser (120).

This steam flash tank (210) can store the circulating water by separating it into steam (gas phase) and water (liquid phase), and accordingly, the circulating water can be discharged in a water state through a circulating path (220) and in a steam state through a steam path (230).

The circulation path (220) guides the circulation water to circulate through the condenser (120) and the steam flash tank (210).

Referring to FIG. 3, the circulation path (220) may include a first circulation path (221) that guides the circulation water to flow from the steam flash tank (210) to the condenser (120), and a second circulation path (222) that guides the circulation water that has absorbed heat in the condenser (120) to flow back into the steam flash tank (210).

Accordingly, the circulating water is supplied to the condenser (120) through the first circulation path (221) to absorb the heat released by the high-temperature and high-pressure refrigerant as it condenses, and the circulating water that has absorbed the heat is introduced into the steam flash tank (210) through the second circulation path (222).

The steam path (230) can discharge steam generated in the steam flash tank (210) to the outside. In other words, the steam path (230) can supply steam to a place that requires steam.

The circulating water, which circulates in this manner and repeats the absorption and release of heat, may gradually become contaminated and cause fouling or scaling in the condenser (120). Since fouling or scaling may deteriorate the heat exchange performance of the condenser (120), a purification process may be performed to discharge a portion of the circulating water and replenish clean water to prevent this.

To this end, the circulating water discharge path (240) may be configured to discharge a portion of the circulating water. In addition, the circulating water supply path (250) may be configured to replenish clean water to the circulating water. Valves for controlling the amount of circulating water (or water) discharged or replenished may be installed in each of the circulating water discharge path (240) and the circulating water supply path (250).

Each of the circulation water discharge path (240) and the circulation water supply path (250) can be connected to either the circulation path (220) or the steam flash tank (210).

Fig. 4 is a conceptual diagram schematically illustrating various embodiments of a steam generating device (200) according to the present invention. The arrangement relationship of components forming the steam generating device (200) may have various embodiments as shown in Fig. 4.

The steam generator (200) may be configured such that the circulating water discharge path (240) is connected to the steam flash tank (210), as shown in Fig. 4(a), and the circulating water supply path (250) is connected to the first circulating path (221) among the circulating paths (220).

Alternatively, the steam generator (200) may be configured such that both the circulating water discharge path (240) and the circulating water supply path (250) are connected to the steam flash tank (210), as shown in FIG. 4(b).

Alternatively, the steam generator (200) may be configured such that both the circulating water discharge path (240) and the circulating water supply path (250) are connected to the first circulating path (221), as shown in FIG. 4(c).

Meanwhile, the steam generation device (200) may be installed on a circulation path (220) and may include a pump (260) that creates a flow of circulating water. The circulating water may be circulated along the circulation path (220) by the pump (260).

At least one pump (260) can be installed, and FIGS. 3 and 4 show a state where one pump (260) is installed.

As shown in (a) to (c) of FIG. 4, the pump may be installed on the first circulation path (221), but as shown in (d) of FIG. 4, it may also be installed on the second circulation path (222).

Even if the purpose of the circulating water is not purification, some of it may be discharged or more may be supplied depending on the state of the steam generating device (200). That is, the steam flash tank (210) may discharge some of the circulating water to reduce the amount of circulating water, or supply more water to the circulating water to increase the amount of circulating water, depending on the amount of circulating water stored. For this purpose, the steam flash tank (210) may be equipped with a flow meter that measures the amount of circulating water.

A heat pump-type steam generation system (10) including a heat pump (100) and a steam generation device (200) is capable of generating steam of 150°C or higher.

Furthermore, it is preferable that this heat pump type steam generation system (10) be operated in a supercritical cycle in which heat dissipation in the condenser (120) is performed above the critical point in order to obtain high temperature steam.

Above, the structure of a heat pump-type steam generation system (10) that effectively cools a double-suction centrifugal compressor (110) equipped in a heat pump (100) to stably produce steam has been described.

Hereinafter, a cooling method of the double-suction centrifugal compressor (110) will be specifically described with reference to Fig. 5. Fig. 5 is a flow chart showing a cooling method of the double-suction centrifugal compressor (110) equipped in the heat pump (100) according to the present invention.

First, in the present invention, a process of detecting the degree of overheating of a motor (113) equipped in a double-suction centrifugal compressor (110) can be performed (S510).

For this purpose, the double-suction centrifugal compressor (110) may be equipped with a motor-side sensor (119) that measures the temperature of the motor (113).

The motor side sensor (119) can directly or indirectly measure the temperature of the motor (113). Therefore, in some cases, the temperature of the motor (113) may mean the ambient temperature of the motor (113).

In Fig. 2, the motor-side sensor (119) measures the ambient temperature of the motor (113). The motor-side sensor (119) may be a composite sensor that comprehensively measures pressure, etc. in addition to temperature.

When measuring the ambient temperature of the motor (113), the present invention may include an additional process for compensating the temperature of the motor (113). For example, when measuring the ambient temperature of the motor (113), the control unit may consider a value obtained by adding a predetermined temperature to the temperature measured by the motor-side sensor (119) as the temperature of the motor (113).

If the ambient temperature of the motor (113) is measured and considered as the temperature of the motor (113) without separate compensation, the subsequent process can be set to be applied based on the ambient temperature of the motor (113).

The control unit can detect the degree of overheating of the motor (113) based on the motor temperature received from the motor side sensor (119). For example, the control unit can determine that the motor (113) is in an overheated state if the motor temperature exceeds the 'motor limit temperature' for more than 5 seconds.

The control unit can express the degree of overheating of the motor (113) as a temperature or as a plurality of stages. For example, the control unit can express a good stage when the motor temperature is T1 or more and less than T2, a warning stage when it is T2 or more and less than T3, and a dangerous stage when it is T3 or more.

Next, in the present invention, a process of calculating the required flow rate of refrigerant for cooling based on the degree of overheating of the motor (113) can be performed (S520).

At this time, matching data matching the degree of overheating of the motor (113) and the required flow rate of the cooling refrigerant may be input into the control unit. The matching data may include, for example, information that when the motor temperature is in the good stage, the required flow rate of the cooling refrigerant is Q1, and when the motor temperature is in the warning stage, the required flow rate of the cooling refrigerant is Q2.

Such matching data can be obtained experimentally.

The control unit can use this matching data to calculate the required flow rate of the cooling refrigerant. Alternatively, the control unit can use the relationship between the cooling refrigerant and the required flow rate of the cooling refrigerant to calculate the required flow rate of the cooling refrigerant.

Next, in the present invention, a process of controlling the flow rate of the cooling refrigerant flowing in the cooling path (1051) so that the cooling refrigerant is injected into the interior of the double-suction centrifugal compressor (110) in the amount of the required flow rate of the cooling refrigerant can be performed (S530).

To this end, a cooling refrigerant flow sensor capable of measuring the flow rate of the cooling refrigerant flowing in the cooling refrigerant flow path (1051) may be installed on the cooling duct (1051).

The control unit can compare the flow rate of the cooling refrigerant transmitted by the cooling refrigerant flow rate sensor with the required flow rate of the cooling refrigerant. If the flow rate of the cooling refrigerant is less than the required flow rate of the cooling refrigerant, the control unit can gradually open the cooling flow valve (180) until the flow rate of the cooling refrigerant reaches the required flow rate of the cooling refrigerant.

When the flow rate of the cooling refrigerant reaches the required flow rate of the cooling refrigerant, the control unit can stop adjusting the cooling flow valve (180) until the motor (113) is out of the overheated state or the motor temperature enters a stable state. Thereafter, when a preset condition is satisfied, the control unit can adjust the opening of the cooling flow valve (180) to reduce the flow rate of the cooling refrigerant. The preset condition may be a case where the motor (113) continues in a non-overheated state for a predetermined period of time or longer.

According to another example, the control unit can cool the double-suction centrifugal compressor (110) without calculating the required flow rate. Accordingly, when the motor (113) is in an overheated state, the control unit can further open the valve (180), and when it is determined that the temperature of the motor has sufficiently decreased, the control unit can further close the cooling flow valve (180) to reduce the flow rate of the cooling refrigerant.

Here, the refrigerant for cooling is a portion of the refrigerant flowing from the internal heat exchanger (170) to the second expansion valve (150), as described above.

In addition, as described above, the refrigerant for cooling flows along the return path (1052) after cooling the double-suction centrifugal compressor (110) and is combined with the refrigerant flowing into (sucked into) the inlet of the double-suction centrifugal compressor (110). Accordingly, the refrigerant flowing into (sucked into) the double-suction centrifugal compressor (110) is a refrigerant mixed with the refrigerant for cooling.

The refrigerant for cooling and the refrigerant can be mixed in different states such as temperature or pressure. Specifically, the temperature of the refrigerant for cooling can rise while cooling the double-suction centrifugal compressor (110), and the temperature of the refrigerant for cooling can be higher than that of the refrigerant.

In this case, the refrigerant mixed with the cooling refrigerant can have a temperature-rising effect, which can be used to efficiently control the superheating of the refrigerant.

Accordingly, the control unit can control the flow rate of the refrigerant so that the refrigerant mixed by the merging reaches a preset superheat (or is within a preset superheat range).

To this end, the heat pump (100) may further include at least one temperature sensor for measuring the temperature of the refrigerant sucked into the double-suction centrifugal compressor (110) and at least one pressure sensor for measuring the pressure of the refrigerant sucked into the double-suction centrifugal compressor (110).

The temperature sensor may be installed at least one of the low-stage inlet (111a) side, the high-stage outlet (112b) side, and the housing (110a) of the double-suction centrifugal compressor (110), and the pressure sensor may also be installed at least one of the low-stage inlet (111a) side, the high-stage outlet (112b) side, and the housing (110a) of the double-suction centrifugal compressor (110).

The control unit receives temperature information and pressure information measured from the temperature sensor and pressure sensor, detects the superheat of the mixed refrigerant, and determines whether the superheat of the mixed refrigerant has reached a preset superheat (or is within a preset superheat range).

For example, the control unit can calculate the pre-compression superheat of the mixed refrigerant by using the pressure sensor installed on the low-stage inlet (111a) side of the double-suction centrifugal compressor (110) as well as the temperature sensor installed on the low-stage inlet (111a) side of the double-suction centrifugal compressor (110). If the pre-compression superheat of the mixed refrigerant does not reach a preset superheat, the control unit can adjust the flow rate of the refrigerant flowing through the first passage (101) to the eighth passage (108) of the heat pump (100) to increase or decrease the superheat. To this end, the heat pump (100) can include an accumulator (not shown) capable of storing a portion of the refrigerant. If the control unit wants to increase the flow rate of the refrigerant, it can decrease the storage amount in the accumulator, and if the control unit wants to decrease the flow rate of the refrigerant, it can increase the storage amount in the accumulator.

The control unit may also control the first expansion valve (130) or the second expansion valve (150) to regulate the flow rate of refrigerant flowing in the system.

The control unit may also adjust physical quantities or state values other than the flow rate of the refrigerant to increase or decrease the superheat level.

According to another example, the control unit may calculate the superheat degree of the mixed refrigerant after compression by using a temperature sensor installed on the high-stage outlet (112b) side of the double-suction centrifugal compressor (110) and a pressure sensor installed on the high-stage outlet (112b) side of the double-suction centrifugal compressor (110), and may also control the flow rate of the refrigerant based on the superheat degree.

According to another example, the control unit can also calculate the superheat level by using a pressure sensor and a temperature sensor installed on one of the first to eighth passages (101) to (108) flowing into the double-suction centrifugal compressor (110), and a pressure sensor and a temperature sensor installed on the cooling passage (1051).

In this way, the control unit can control the flow rate of refrigerant circulating in the cycle of the heat pump (100).

In addition, the control unit can control the heat pump (100) as a whole. Accordingly, the control unit can control at least one of the impeller (118) and the motor (113) provided in the double-suction centrifugal compressor (110).

Furthermore, the double-suction centrifugal compressor (110) may be equipped with an inverter for controlling the motor (113), and the control unit may indirectly control the motor (113) through the inverter.

In this specification, unless the low-stage inlet (111a) side and the high-stage inlet (112a) side of the double-suction centrifugal compressor (110) are distinguished, the inlet side of the double-suction centrifugal compressor (110) should be regarded as the low-stage inlet (111a) side of the double-suction centrifugal compressor (110).

In addition, the refrigerant introduced into the double-suction centrifugal compressor (110) in this specification means a refrigerant in which a cooling refrigerant is mixed with the refrigerant before being discharged from the internal heat exchanger (170) and introduced into the double-suction centrifugal compressor (110).

Meanwhile, the above detailed description should not be construed as restrictive in all respects but should be considered as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (10)

A double-suction centrifugal compressor that compresses the refrigerant compressed at a low stage once more at a high stage;
A condenser for condensing the refrigerant so that heat is released from the refrigerant passing through the double-suction centrifugal compressor;
A first expansion valve for expanding the refrigerant passing through the condenser;
A refrigerant flash tank that separates the refrigerant passing through the first expansion valve into a gas phase and a liquid phase;
A second expansion valve for expanding the liquid refrigerant discharged from the refrigerant flash tank;
An evaporator that absorbs heat energy from a heat source and evaporates the refrigerant that has passed through the second expansion valve;
An internal heat exchanger installed between the refrigerant flash tank and the second expansion valve to allow heat exchange between the refrigerant before it passes through the evaporator and flows into the double-suction centrifugal compressor and the refrigerant discharged in a liquid phase from the refrigerant flash tank;
A cooling path branched between the internal heat exchanger and the second expansion valve to guide a portion of the refrigerant to be injected into the interior of the double-suction centrifugal compressor as a cooling refrigerant; and
A heat pump using a double-suction centrifugal compressor, which includes a return path for guiding the cooling refrigerant so that the cooling refrigerant cools the inside of the double-suction centrifugal compressor and then is discharged to join the refrigerant flowing into the double-suction centrifugal compressor from the internal heat exchanger at the low-stage inlet side. In the first paragraph,
A cooling channel valve installed on the above cooling channel; and
It further includes a control unit that controls the opening of the cooling flow valve so that the flow rate of the cooling refrigerant is adjusted,
A heat pump using a double-suction centrifugal compressor, characterized in that the control unit controls the flow rate of the refrigerant so that the refrigerant mixed by the joining is within a preset superheat range. In the second paragraph,
A temperature sensor for measuring the temperature of the refrigerant sucked into the double-suction centrifugal compressor; and
Further comprising a pressure sensor for measuring the pressure of the refrigerant sucked into the double-suction centrifugal compressor;
The above control unit,
Detecting the superheating of the mixed refrigerant by receiving measurement information from the above temperature sensor and the above pressure sensor,
A heat pump using a double-suction centrifugal compressor, characterized in that it determines whether the superheat of the mixed refrigerant is within the preset superheat range. In the first paragraph,
The above double suction centrifugal compressor,
A motor providing power to compress the above refrigerant;
An injection port opened to inject the cooling refrigerant toward the inside where the motor is located; and
Including a discharge port opened to discharge the cooling refrigerant that cools the above motor,
A heat pump using a double-suction centrifugal compressor, characterized in that the injection part and the discharge part are respectively provided on both sides with the stator of the motor interposed therebetween. In paragraph 4,
A heat pump using a double-suction centrifugal compressor, wherein the double-suction centrifugal compressor further includes a spray nozzle connected to the cooling path and installed in the injection unit to lower the temperature of the cooling refrigerant and spray it. In paragraph 4,
The above-mentioned double-suction centrifugal compressor further includes a magnetic bearing supporting the shaft of the motor,
The above magnetic bearings,
Two radial bearings arranged opposite each other with the above motor in between; and
It includes a thrust bearing arranged between the high-side radial bearing among the above two radial bearings and the motor,
The above injection part is located on one side of the stator corresponding to the high side,
A heat pump using a double-suction centrifugal compressor, characterized in that the discharge portion is located on the other side of the stator corresponding to the low-stage side. In Article 6,
The above-mentioned double-suction centrifugal compressor further includes an impeller that causes the flow of the refrigerant,
The above impellers are installed on each of the low stage inlet side and the high stage inlet side,
The above injection part,
A first inlet located between the high-side radial bearing and the high-side impeller; and
A heat pump using a double-suction centrifugal compressor, characterized in that it includes a second inlet located on the side surface of the thrust bearing. In the first paragraph,
The above-mentioned double-suction centrifugal compressor further includes a cooling jacket surrounding the outer surface of the housing,
A heat pump using a double-suction centrifugal compressor, characterized in that the cooling jacket is provided with a supply port for supplying cooling water and a discharge port for discharging cooling water. A heat pump according to any one of claims 1 to 8, for transferring heat absorbed from a low-temperature heat source to a high-temperature heat source; and
It includes a steam generating device that generates steam through heat exchange with the condenser of the above heat pump,
The above steam generating device,
A steam flash tank that generates steam by utilizing the heat released from the condenser through circulating water;
A circulation path that guides the above-mentioned circulating water to circulate through the above-mentioned condenser and the above-mentioned steam flash tank;
A circulation water discharge path connected to one of the above circulation path and the above steam flash tank so that a portion of the circulation water is discharged; and
A heat pump type steam generation system including a circulating water supply path connected to one of the above circulating water path and the above steam flash tank to replenish water to the circulating water. In Article 9,
The above refrigerant is R1336mzz(Z),
A heat pump type steam generation system characterized by generating steam of 150°C or higher.