JP7615076B2 - Steam Generator - Google Patents

Description

An embodiment of the present invention relates to a steam generating device.

In industrial manufacturing processes, steam is sometimes used to manufacture products, and the steam generated in a boiler is supplied to the steam utilization equipment.

However, boilers generally use so-called fossil fuels such as coal, heavy oil, and natural gas as fuel. _CO2 produced by burning fossil fuels is one of the causes of global warming. Therefore, there is a demand to reduce the amount of fossil fuels burned.

In such circumstances, steam generators using a heat pump cycle that does not generate _CO2 as the steam generation cycle are being used.

Figure 13 is a system diagram of a conventional steam generator 300 that uses a heat pump cycle. Figure 14 is a p-h (pressure-enthalpy) diagram (Mollier diagram) of the heat pump cycle in the conventional steam generator 300 shown in Figure 13.

The horizontal axis of FIG. 14 indicates specific enthalpy h (kJ/kg), and the vertical axis indicates pressure P (MPa). Also, in FIG. 14, the dashed lines indicate isotherms. The temperatures indicated by the isotherms increase toward the right.

Figure 14 also shows the saturated vapor line 330, the saturated liquid line 331, and the critical point 332. In addition, in the cycle of the heat pump system in the conventional steam generating device 300, the states of the refrigerant are shown as state 320-state 323.

As shown in FIG. 13, the steam generating device 300 includes a compressor 310, a condenser 311, an expansion valve 312, and an evaporator 313. The compressor 310 is driven by, for example, a drive unit 310a. A refrigerant flows through the heat pump cycle.

In the evaporator 313, the refrigerant absorbs heat from the introduced external fluid 314a and evaporates (from state 323 to state 320 in FIG. 14). Note that the temperature of the external fluid 314b that has passed through the evaporator 313 is lower than the temperature of the introduced external fluid 314a.

The external fluid used may be waste heat from a factory. It is generally known that the higher the temperature of the external fluid, the better the performance of the heat pump cycle.

The low-pressure refrigerant vapor that has evaporated in the evaporator 313 becomes high temperature and high pressure in the compressor 310 (from state 320 to state 321 in FIG. 14). The high-temperature, high-pressure refrigerant in the compressor 310 is introduced into the condenser 311. The refrigerant then releases heat to the water 315a introduced into the condenser 311, and is cooled (from state 321 to state 322 in FIG. 14). The water 315a boils and becomes vapor 315b, which is released from the condenser 311.

The refrigerant whose temperature has been reduced in the condenser 311 is throttled and expanded by the expansion valve 312 (from state 322 to state 323 in FIG. 14). Then, the refrigerant, whose pressure and temperature have been reduced and which has become liquid, is guided to the evaporator 313.

Patent No. 5223937

In order to stably generate steam while maintaining high cycle performance in a heat pump cycle, the state of the refrigerant at the outlet of the evaporator 313 is an important factor. However, in a conventional steam generating device 300 using a heat pump cycle, maintaining high cycle performance by adjusting the state of the refrigerant at the outlet of the evaporator 313 has not been considered.

The problem that this invention aims to solve is to provide a steam generating device that can maintain high cycle performance in a heat pump cycle by adjusting the state of the refrigerant at the outlet of the evaporator.

The steam generating device of one embodiment includes a heat pump system that circulates refrigerant through a compressor, a radiator, a heat exchanger, an expansion section, an evaporator, and the heat exchanger in that order, and exchanges heat in the heat exchanger between a low-pressure side refrigerant that has passed through the evaporator and a high-pressure side refrigerant that has passed through the radiator, a fluid supply section that supplies the evaporator with a fluid that imparts heat to the refrigerant in the evaporator, and a water supply section that supplies the radiator with water for generating steam by heat exchange with the refrigerant in the radiator, and adjusts at least one of the opening degree of the expansion section and the amount of heat exchange in the evaporator based on the state quantity of the refrigerant at the outlet of the evaporator .

Furthermore, the steam generating device includes a heat exchange amount calculation unit that calculates the heat exchange amount in the evaporator, a heat exchange amount determination unit that determines whether the heat exchange amount calculated by the heat exchange amount calculation unit is equal to or less than a heat exchange amount allowable value in the evaporator, and a heat exchange amount adjustment unit that adjusts the heat exchange amount in the evaporator based on the determination of the heat exchange amount determination unit .

1 is a system diagram of a steam generating device according to an embodiment. A PH diagram of a heat pump system of a steam generating device of an embodiment. 2 is a block diagram showing a configuration of a control device of a steam generating device according to an embodiment. FIG. 3 is a ph diagram showing the amount of change in enthalpy in the ph diagram of the heat pump system 5 of the steam generating device of the embodiment shown in FIG. 2. FIG. 2 is a diagram showing the relationship between the enthalpy ratio and the COP ratio in a heat pump system of the steam generating device according to the embodiment. FIG. 4 is a diagram showing the relationship between the wetness, the degree of superheat, and the COP ratio in the heat pump system of the steam generating apparatus according to the embodiment. 4 is a diagram showing an outline of a calculation flow of a refrigerant state quantity calculation unit in the control device of the steam generating device of the embodiment. FIG. 5 is a flowchart illustrating an operation for adjusting a state of the refrigerant at an outlet of the evaporator in the steam generating device according to the embodiment. 1 is a diagram showing a schematic arrangement of a steam generating device according to an embodiment in which an evaporator is installed at a higher position than other devices. FIG. FIG. 9 is a ph (pressure-enthalpy) diagram of a heat pump system when a steam generating device according to an embodiment is installed. FIG. 11 is a system diagram of a steam generating device having another configuration of the embodiment. FIG. 11 is a system diagram of a steam generating device having another configuration of the embodiment. FIG. 1 is a system diagram of a conventional steam generating device using a heat pump cycle. FIG. 14 is a p-h diagram of a heat pump cycle in the conventional steam generating device shown in FIG. 13.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a system diagram of a steam generating device 1 according to an embodiment.

1 , the steam generating device 1 includes a heat pump system 5 including a compressor 10, a radiator 20, a heat exchanger 30, an expansion section 40, and an evaporator 50, a control device 60, and a detection section 100. The steam generating device 1 also includes a fluid supply pipe 51 that supplies fluid to the evaporator 50, a fluid discharge pipe 52 that discharges the fluid from the evaporator 50, a water supply pipe 21 that supplies water to the radiator 20, and a steam discharge pipe 22 that discharges steam from the radiator 20.

Here, the fluid supply pipe 51 functions as a fluid supply section, and the water supply pipe 21 functions as a water supply section.

The heat pump system 5 circulates the refrigerant through the compressor 10, radiator 20, heat exchanger 30, expansion section 40, evaporator 50, and heat exchanger 30 in that order. These are connected in sequence via piping. In the heat pump system 5, the refrigerant that has passed through the evaporator 50 and the refrigerant that has passed through the radiator 20 are heat exchanged in the heat exchanger 30. The compressor 10 is equipped with a drive device 11 that drives the compressor 10.

Hereinafter, the refrigerant that is led to the heat exchanger 30 after passing through the evaporator 50 is referred to as the low-pressure side refrigerant, and the refrigerant that is led to the heat exchanger 30 after passing through the radiator 20 is referred to as the high-pressure side refrigerant.

The compressor 10 compresses the refrigerant that has evaporated in the evaporator 50 and been heated in the heat exchanger 30 to produce a high-temperature, high-pressure refrigerant. The compressor 10 is driven by a drive device 11. The drive device 11 is composed of, for example, a motor, a gas engine, a turbine, etc.

The radiator 20 generates steam by heat exchange between water introduced from outside and a high-temperature, high-pressure refrigerant. The water supply pipe 21 introduces water that becomes steam through heat exchange with the refrigerant into the radiator 20. The water is introduced from outside into the water supply pipe 21 by a pressure-feeding device such as a pump (not shown).

The steam exhaust pipe 22 exhausts the steam generated by transferring the heat radiated by the refrigerant to water from the radiator 20. The steam exhausted from the radiator 20 is supplied to a steam-using section, such as a manufacturing process in a manufacturing plant.

The heat exchanger 30 exchanges heat between the low-pressure refrigerant that has passed through the evaporator 50 and the high-pressure refrigerant that has passed through the radiator 20. The heat exchanger 30 is configured to exchange heat between the high-pressure refrigerant that has passed through the radiator 20 flowing through a pipe and the low-pressure refrigerant that has passed through the evaporator 50 introduced into the heat exchanger 30, for example.

The expansion section 40 expands the refrigerant that has released heat in the heat exchanger 30, lowering its temperature and pressure. The refrigerant that has passed through the expansion section 40 becomes liquid or wet vapor. The expansion section 40 may be configured to expand the refrigerant to lower its temperature and pressure. For example, an expansion valve, an orifice, a turbine, or the like may be used as the expansion section 40.

The evaporator 50 evaporates the refrigerant by heat exchange between the refrigerant and a fluid introduced from the outside. The fluid supply pipe 51 supplies the evaporator 50 with a fluid that provides heat to the refrigerant flowing through the piping inside the evaporator 50. The fluid discharge pipe 52 discharges the fluid that has heated the refrigerant from the evaporator 50.

The temperature of the refrigerant discharged from the fluid discharge pipe 52 is lower than the temperature of the refrigerant supplied from the fluid supply pipe 51. The fluid supply pipe 51 is provided with a flow rate adjustment valve 51a. The flow rate adjustment valve 51a may also be provided in the fluid discharge pipe 52.

Here, the fluid introduced into the evaporator 50 may be any fluid having a higher temperature than the refrigerant flowing through the evaporator 50. In other words, the fluid introduced into the evaporator 50 may be any fluid having a heat quantity that causes the refrigerant to evaporate in the evaporator 50. This fluid is not particularly limited, but examples of the fluid include seawater, river water, and air.

For example, when generating a large amount of steam in the radiator 20, it is effective to use a fluid that exists in large quantities in nature, such as seawater, river water, or the atmosphere, as the fluid to be introduced into the evaporator 50. Even during cold seasons such as winter, the fluid to be introduced into the evaporator 50 must be a fluid with a higher temperature than the temperature of the refrigerant flowing through the evaporator 50.

Fluid is also introduced into the fluid supply pipe 51 from the outside by a pressure device such as a pump or a blower such as a fan (not shown).

For example, when air is supplied to the evaporator 50 by a fan or the like, the fluid supply pipe 51 is configured with a large-diameter cylinder or the like corresponding to the size of the heat exchanger in the evaporator 50. Then, for example, air is supplied to the heat exchanger of the evaporator 50 from below via the fluid supply pipe 51 by a fan installed on the below side of the heat exchanger of the evaporator 50.

The refrigerant used here is one whose standard boiling point is lower than that of the fluid supplied to the evaporator 50, or one that has no standard boiling point. Note that the standard boiling point is the boiling point of the medium at standard atmospheric pressure.

The boiling point of a refrigerant decreases when the pressure of the refrigerant is reduced. However, there is a limit to how much the pressure of the refrigerant can be reduced in a heat pump cycle. In other words, a vacuum pump or similar device is required to reduce the pressure inside the heat pump cycle below atmospheric pressure. This requires power to operate the vacuum pump, which reduces cycle performance.

Therefore, by using a refrigerant whose standard boiling point is lower than that of the fluid supplied to the evaporator 50, or a refrigerant that has no standard boiling point, the refrigerant can be evaporated in the evaporator 50 without lowering the pressure in the heat pump cycle below atmospheric pressure.

In addition, specifically, for example, R1234ze (E), R1234yf, _CO2, etc. may be used as the refrigerant. These refrigerants have a low global warming potential (GWP) of 1 and an ozone depletion potential (ODP) of "0". Therefore, there is almost no impact on the environment. In addition, these refrigerants are highly safe because they are low toxic.

The detection unit 100 and control device 60 will be described later.

In addition, the steam generating device 1 shown in FIG. 1 may be equipped with other devices depending on the functions required of the steam generating device 1. In addition, the heat pump system 5 described above may be used in combination with other systems.

Here, we will first explain the function of the refrigerant in the heat pump system 5 of the steam generating device 1.

Figure 2 is a p-h (pressure-enthalpy) diagram (Mollier diagram) of the heat pump system 5 of the steam generating device 1 of the embodiment. The horizontal axis of Figure 2 indicates the specific enthalpy h (kJ/kg), and the vertical axis indicates the pressure P (MPa). In Figure 2, isotherms are shown by dashed lines. The temperatures indicated by the isotherms increase as you move to the right.

2 also shows a saturated vapor line 110, a saturated liquid line 111, and a critical point 112. In addition, the cycle of the heat pump system 5 shows the refrigerant states in states A to F.

Note that FIG. 2 shows an example in which the state B of the refrigerant at the outlet of the compressor 10 is higher than the critical pressure. Note that the state B of the refrigerant at the outlet of the compressor 10 may be lower than the critical pressure depending on the operating state, the type of refrigerant, etc. This embodiment can also be applied when the state B of the refrigerant at the outlet of the compressor 10 is lower than the critical pressure.

The refrigerant sucked into the compressor 10 is compressed from state A to high temperature and high pressure state B. During this process, the refrigerant has sufficient temperature, or enthalpy, to boil water in the radiator 20.

The refrigerant then releases heat to the water supplied from the water supply pipe 21 in the radiator 20, changing from state B to state C. The water supplied to the radiator 20 from the water supply pipe 21 becomes wet steam or superheated steam depending on the amount of heat from the refrigerant. The generated steam is discharged from the steam discharge pipe 22 and supplied to the steam utilization section, etc.

Here, a preheater for preheating water may be provided in the water supply pipe 21. In this case, for example, water at 20°C becomes water at 90°C in the preheater. Then, this heated water is supplied from the water supply pipe 21 to the radiator 20.

A superheater for heating the steam may also be provided in the steam exhaust pipe 22. In this case, for example, the degree of superheating of the steam can be adjusted according to the requirements of the steam utilization section.

The refrigerant flowing out from the radiator 20 releases heat to the low-pressure side refrigerant flowing out from the evaporator 50 in the heat exchanger 30, and changes from state C to state D. The refrigerant flowing out from the radiator 20 is the high-pressure side refrigerant described above. In the heat exchanger 30 , the high-pressure side refrigerant is heat exchanged with the low-pressure side refrigerant flowing out from the evaporator 50, and the enthalpy decreases.

As shown in FIG. 2, the state of the high-pressure side refrigerant is not wet vapor at the inlet and outlet of the high-pressure side refrigerant in the heat exchanger 30. Therefore, by detecting the temperature and pressure at the inlet and outlet of the high-pressure side refrigerant in the heat exchanger 30, the state quantity of the high-pressure side refrigerant at each position can be grasped.

The refrigerant that flows out of the heat exchanger 30 flows into the expansion section 40. The refrigerant is depressurized in the expansion section 40, and changes from state D to state E. As shown in FIG. 2, in state E, the refrigerant is in a wet vapor state.

The refrigerant flowing out of the expansion section 40 flows into the evaporator 50. In the evaporator 50, the refrigerant absorbs heat from the fluid supplied from the fluid supply pipe 51, changing from state E to state F. In other words, the state of the refrigerant at the outlet of the evaporator 50 is state F. The fluid that has released heat to the refrigerant is discharged from the fluid discharge pipe 52.

Here, the steam generating device 1 maintains high cycle performance by adjusting the state of the refrigerant at the outlet of the evaporator 50. The adjustment of the state of the refrigerant at the outlet of the evaporator 50 will be described later.

The refrigerant that flows out of the evaporator 50 flows into the heat exchanger 30 as a low-pressure side refrigerant. The low-pressure side refrigerant absorbs heat from the high-pressure side refrigerant in the heat exchanger 30, changing from state F to state A. Then, the refrigerant that has absorbed heat from the high-pressure side refrigerant flows back into the compressor 10.

Next, the configuration of the detection unit 100 and the control device 60 will be described. In addition, the configuration for maintaining high cycle performance by adjusting the state of the refrigerant at the outlet of the evaporator 50 will be described.

As shown in FIG. 1, the detection unit 100 includes a temperature detection unit 101 that detects the temperature (Tin1) of the high-pressure side refrigerant at the inlet of the high-pressure side refrigerant of the heat exchanger 30, a pressure detection unit 102 that detects the pressure (Pin1) of the high-pressure side refrigerant at the inlet of the high-pressure side refrigerant of the heat exchanger 30, a temperature detection unit 103 that detects the temperature (Tout1) of the high-pressure side refrigerant at the outlet of the high-pressure side refrigerant of the heat exchanger 30, and a pressure detection unit 104 that detects the pressure (Pout1) of the high-pressure side refrigerant at the outlet of the high-pressure side refrigerant of the heat exchanger 30.

The detection unit 100 also includes a temperature detection unit 105 that detects the temperature (Tout2) of the low-pressure side refrigerant at the outlet of the low-pressure side refrigerant of the heat exchanger 30, and a pressure detection unit 106 that detects the pressure (Pout2) of the low-pressure side refrigerant at the outlet of the low-pressure side refrigerant of the heat exchanger 30.

The detection unit 100 further includes a pressure detection unit 107 that detects the pressure (Pout3) of the refrigerant at the outlet of the evaporator 50. The detection unit 100 also includes a temperature detection unit 108 that detects the temperature (Tin4) of the fluid supplied to the evaporator 50, and a temperature detection unit 109 that detects the temperature (Tout4) of the fluid discharged from the evaporator 50.

The control device 60 performs various calculations based on the detection signal from the detection unit 100, and adjusts the opening degree of the expansion unit 40 and the amount of heat exchange in the evaporator 50. Figure 3 is a block diagram showing the configuration of the control device 60 of the steam generating device 1 of the embodiment.

As shown in FIG. 3, the control device 60 includes an input unit 70, a memory unit 80, a calculation unit 90, and an output unit 75.

The input unit 70 inputs detection signals from the detection unit 100 and input signals for changing the operating state of the steam generating device 1. The input unit 70 inputs detection signals from, for example, the temperature detection units 101, 103, 105, 108, and 109 and the pressure detection units 102, 104, 106, and 107. The input unit 70 also inputs detection signals from various flow meters (not shown) that detect the flow rates of the fluid passing through the evaporator 50 and the high-pressure side refrigerant and low-pressure side refrigerant flowing through the heat exchanger 30.

The memory unit 80 is composed of a storage medium such as a read-only memory (ROM) or a random access memory (RAM). The memory unit 80 includes a refrigerant state memory unit 81 and a heat exchange amount memory unit 82.

The refrigerant state memory unit 81 stores data necessary to calculate the state quantities of the refrigerant, data necessary to identify the state of the refrigerant, etc. The refrigerant state memory unit 81 stores, for example, various data based on a steam table, saturation temperature at each pressure, enthalpy based on pressure and temperature, enthalpy on the saturated vapor line, wetness calculated from pressure and enthalpy, degree of superheat, etc.

The refrigerant state storage unit 81 also stores thresholds and the like for determining whether the state of the refrigerant at the outlet of the evaporator 50 is within a predetermined state range. For example, a first state parameter and a second state parameter are set as state parameters specifying the state of the refrigerant at the outlet of the evaporator 50. A first threshold is set for the first state parameter, and a second threshold is set for the second state parameter.

Here, we first explain the first state parameter and the first threshold.

Figure 4 is a p-h diagram showing the amount of change in enthalpy in the p-h diagram of the heat pump system 5 of the steam generating device 1 of the embodiment shown in Figure 2. In Figure 4, the amount of change in enthalpy of the refrigerant from the inlet to the outlet of the evaporator 50 (state E-state F) is H1, the amount of change in enthalpy based on the exchange of heat between the low-pressure side refrigerant and the high-pressure side refrigerant in the heat exchanger 30 (state F-state A, state C-state D) is H2, the amount of change in enthalpy of the refrigerant from the inlet to the outlet of the compressor 10 (state A-state B) is H3, and the amount of change in enthalpy of the refrigerant from the inlet to the outlet of the radiator 20 (state B-state C) is H4.

The difference between the enthalpy of the refrigerant at the inlet of the evaporator 50 (state E) and the enthalpy (Hsat) on the saturated vapor line 110 at the vapor pressure of the refrigerant in state F is shown as HE, and the difference between the enthalpy of the refrigerant at the outlet of the evaporator 50 (state F) and the enthalpy (Hsat) is shown as ΔH.

In other words, enthalpy (Hsat) is the enthalpy at the point on the p-h diagram where the refrigerant pressure isobar at the outlet of the evaporator 50 (state F) and the saturated vapor line 110 intersect.

Note that ΔH is the value obtained by subtracting the enthalpy (Hsat) from the enthalpy of the refrigerant at the outlet of the evaporator 50 (state F).

Here, when ΔH is "0", the enthalpy of the refrigerant at the outlet (state F) of the evaporator 50 is enthalpy (Hsat). That is, when ΔH is "0", the state F of the refrigerant at the outlet of the evaporator 50 is on the saturated vapor line 110 at the vapor pressure at the refrigerant state F. In other words, when ΔH is "0", the state F of the refrigerant at the outlet of the evaporator 50 is the state at the point where the isobar of the refrigerant pressure at the outlet of the evaporator 50 intersects with the saturated vapor line 110 on the p-h diagram.

When ΔH is negative, the refrigerant state F at the outlet of the evaporator 50 is in the wet vapor region 120. When ΔH is positive, the refrigerant state F at the outlet of the evaporator 50 is in the superheated vapor region 121.

The coefficient of performance (COP) in the cycle of the heat pump system 5 is obtained by dividing the amount of heat obtained in the cycle by the driving power W of the compressor 10. Therefore, the coefficient of performance (COP) in the cycle of the heat pump system 5 is calculated as H4/W. In the following, the coefficient of performance will be referred to as COP.

The higher the COP, the greater the amount of heat that can be obtained for the driving power of the compressor 10. Therefore, the higher the COP, the better the cycle performance. In this embodiment, COP is used as an evaluation index of cycle performance.

Here, we focus on the difference (ΔH) between the enthalpy of the refrigerant at the outlet (state F) of the evaporator 50 and the enthalpy (Hsat) on the saturated vapor line 110. Then, the enthalpy ratio (ΔH/Hsat) obtained by dividing ΔH by the enthalpy (Hsat) and making it dimensionless is set as the first state parameter. In other words, the state F of the refrigerant at the outlet of the evaporator 50 is identified by the enthalpy ratio (ΔH/Hsat).

The enthalpy of the refrigerant at the outlet of the evaporator 50 (state F) functions as the first enthalpy, and the enthalpy (Hsat) functions as the second enthalpy.

Figure 5 is a diagram showing the relationship between the enthalpy ratio (ΔH/Hsat) and the COP ratio in the heat pump system 5 of the steam generating device 1 of the embodiment. The vertical axis of Figure 5 is the COP ratio (COP/COPmax) which is dimensionless, obtained by dividing the COP at each enthalpy ratio by the maximum COP value (COPmax). Note that Figure 5 shows the results obtained by cycle performance calculation.

As shown in FIG. 5, the COP ratio is maximum when the enthalpy ratio is "0". That is, the COP is maximum when the enthalpy ratio is "0". The COP ratio decreases as the enthalpy ratio becomes smaller than "0". Also, the COP ratio decreases as the enthalpy ratio becomes larger than "0".

That is, the COP ratio decreases as the absolute value of the difference (ΔH) between the enthalpy of the refrigerant at the outlet of the evaporator 50 (state F) and the enthalpy (Hsat) on the saturated vapor line 110 increases. In other words, the COP ratio is higher the closer the value of the enthalpy of the refrigerant at the outlet of the evaporator 50 (state F) is to the value of the enthalpy (Hsat) on the saturated vapor line 110.

As described above, in order to obtain excellent cycle performance (high COP), it is preferable to adjust the state F of the refrigerant at the outlet of the evaporator 50 so that the state F of the refrigerant at the outlet of the evaporator 50 approaches the saturated vapor line 110 at the vapor pressure of the refrigerant.

Therefore, based on the results shown in FIG. 5, the threshold range of the enthalpy ratio (ΔH/Hsat), which is the first state parameter, is set to -0.16 or more and 0.14 or less. Note that this threshold is the first threshold. It is more preferable to set the threshold range to -0.10 or more and 0.07 or less. It is even more preferable to set the threshold range to -0.05 or more and 0.04 or less.

By setting the threshold value in the above range, the COP can be maintained at 80% or more of the maximum COP. This allows the heat pump system 5 of the steam generating device 1 to maintain excellent cycle performance.

Next, we will explain the second state parameter and the second threshold.

Figure 6 shows the relationship between the humidity level, the degree of superheat, and the COP ratio in the heat pump system 5 of the steam generating device 1 of the embodiment.

The horizontal axis of FIG. 6 shows the wetness (%) and the degree of superheat (°C). At "0" on the horizontal axis of FIG. 6, the state F of the refrigerant at the outlet of the evaporator 50 is on the saturated vapor line 110 at the vapor pressure of the refrigerant. The left side of "0" on the horizontal axis of FIG. 6 shows the wetness (%), with the wetness increasing as you move to the left. The right side of "0" on the horizontal axis of FIG. 6 shows the superheat (°C), with the superheat increasing as you move to the right. The vertical axis, like FIG. 5, shows the COP ratio (COP/COPmax). Note that FIG. 6 shows the results obtained by cycle performance calculation.

Here, the second state parameters are the wetness and the degree of superheat. That is, the state F of the refrigerant at the outlet of the evaporator 50 is determined by the wetness and the degree of superheat.

As shown in FIG. 6, the COP ratio is maximum when the wetness and superheat are "0". In other words, the COP ratio is maximum when the refrigerant state F at the outlet of the evaporator 50 is on the saturated vapor line 110 at the vapor pressure of the refrigerant. That is, the COP is maximum when the wetness and superheat are "0".

The COP ratio decreases as the wetness increases. The COP ratio also decreases as the degree of superheat increases.

That is, the COP ratio decreases as the refrigerant state F at the outlet of the evaporator 50 moves away from the saturated vapor line 110 at the vapor pressure of the refrigerant. In other words, the COP ratio is higher the closer the refrigerant state F at the outlet of the evaporator 50 is to the saturated vapor line 110.

As described above, in order to obtain excellent cycle performance (high COP), it is preferable to adjust the state F of the refrigerant at the outlet of the evaporator 50 so that the state F of the refrigerant at the outlet of the evaporator 50 approaches the saturated vapor line 110 at the vapor pressure of the refrigerant.

Based on the results shown in Figure 6, the threshold values of the second state parameters, wetness and superheat, are set to the following ranges. The wetness threshold range is 0% to 35.0%, and the superheat threshold range is 0°C to 60.0°C. These thresholds are second thresholds. It is more preferable to set the wetness threshold range to 0% to 20.0%, and the superheat threshold range to 0°C to 31.5°C. It is even more preferable to set the wetness threshold range to 0% to 10.0%, and the superheat threshold range to 0°C to 17.0°C.

By setting the threshold value in the above range, the COP can be maintained at 80% or more of the maximum COP. This allows the heat pump system 5 of the steam generating device 1 to maintain excellent cycle performance.

Here, the refrigerant state memory unit 81 stores the above-mentioned first state parameter, second state parameter, first threshold value of the first state parameter, second threshold value of the second state parameter, etc.

The heat exchange amount storage unit 82 shown in FIG. 3 stores, for example, the heat exchange amount allowable value Qlimit set according to the specifications of the evaporator 50. In the evaporator 50, the maximum allowable heat exchange amount is set from the viewpoint of mechanical strength, etc. The heat exchange amount allowable value Qlimit corresponds to the maximum allowable heat exchange amount.

The calculation unit 90 executes various calculation processes using, for example, programs and data stored in the memory unit 80. The calculation unit 90 includes a refrigerant state quantity calculation unit 91, a refrigerant state identification unit 92, a refrigerant state determination unit 93, a refrigerant state adjustment unit 94, a heat exchange amount calculation unit 95, a heat exchange amount determination unit 96, and a heat exchange amount adjustment unit 97.

The refrigerant state quantity calculation unit 91 calculates the state quantity of the refrigerant at the outlet of the evaporator 50. The refrigerant state quantity calculation unit 91 calculates, for example, the enthalpy of the refrigerant at the outlet of the evaporator 50 based on the detection signal from the detection unit 100. Figure 7 is a diagram showing an overview of the calculation flow of the refrigerant state quantity calculation unit 91 in the control device 60 of the steam generating device 1 of the embodiment.

Here, the enthalpy of the refrigerant at the outlet of the evaporator 50 is considered to be the same as the enthalpy of the low-pressure refrigerant at the inlet of the low-pressure refrigerant of the heat exchanger 30. Then, the enthalpy of the low-pressure refrigerant at the inlet of the low-pressure refrigerant of the heat exchanger 30 is calculated, and the calculated enthalpy is used as the enthalpy of the refrigerant at the outlet of the evaporator 50.

As shown in FIG. 7, the refrigerant state quantity calculation unit 91 calculates the enthalpy (Hout2) of the low-pressure refrigerant at the outlet of the low-pressure refrigerant of the heat exchanger 30 based on the pressure (Pout2) and temperature (Tout2) (step S130).

The refrigerant state quantity calculation unit 91 also calculates the heat exchange quantity of the high-pressure side refrigerant in the heat exchanger 30 (step S131).

Specifically, the refrigerant state quantity calculation unit 91 calculates the enthalpy (Hin1) of the high-pressure side refrigerant at the inlet of the high-pressure side refrigerant of the heat exchanger 30 and the enthalpy (Hout1) of the high-pressure side refrigerant at the outlet of the high-pressure side refrigerant of the heat exchanger 30 based on the pressure (Pin1), temperature (Tin1), pressure (Pout1), and temperature (Tout1). Then, the refrigerant state quantity calculation unit 91 calculates the heat exchange amount of the high-pressure side refrigerant in the heat exchanger 30 based on the calculated enthalpy (Hin1), enthalpy (Hout1), and the flow rate of the high-pressure side refrigerant.

Note that the processes of steps S130 and S131 may be executed in parallel, or either process may be executed first.

Next, the refrigerant state quantity calculation unit 91 calculates the enthalpy of the low-pressure side refrigerant at the inlet of the low-pressure side refrigerant of the heat exchanger 30 based on the enthalpy (Hout2), the flow rate of the low-pressure side refrigerant, the enthalpy (Hin1), the enthalpy (Hout1), and the flow rate of the high-pressure side refrigerant (step S132).

In the heat pump system 5, since there is usually no refrigerant leakage, the enthalpy of the low-pressure refrigerant at the inlet of the low-pressure refrigerant of the heat exchanger 30 is calculated based on the enthalpy (Hout2), enthalpy (Hin1), and enthalpy (Hout1). The flow rate of the high-pressure refrigerant is detected, for example, by a flow meter (not shown) provided at the outlet of the high-pressure refrigerant of the heat exchanger 30. The flow rate of the low-pressure refrigerant is detected by a flow meter (not shown) provided at the outlet of the low-pressure refrigerant of the heat exchanger 30.

The calculated enthalpy of the low-pressure refrigerant at the inlet of the low-pressure refrigerant of the heat exchanger 30 is regarded as the enthalpy of the refrigerant at the outlet of the evaporator 50, as described above.

In this way, the refrigerant state quantity calculation unit 91 calculates the state quantity of the refrigerant at the outlet of the evaporator 50 (the state quantity of the low-pressure side refrigerant flowing into the heat exchanger 30) in the above-mentioned calculation step.

The refrigerant state determination unit 92 determines the state of the refrigerant at the outlet of the evaporator 50 based on the state quantity of the refrigerant calculated by the refrigerant state quantity calculation unit 91, the refrigerant pressure at the outlet of the evaporator 50 (Pout3), and the data of the refrigerant state storage unit 81. Here, the state of the refrigerant at the outlet of the evaporator 50 is determined as the first state parameter or the second state parameter described above.

The refrigerant state determination unit 93 determines whether the state of the refrigerant identified by the refrigerant state determination unit 92 is within a predetermined state range. In other words, the refrigerant state determination unit 93 determines whether the value of the first state parameter identified by the refrigerant state determination unit 92 is within a first threshold range. The refrigerant state determination unit 93 also determines whether the value of the second state parameter identified by the refrigerant state determination unit 92 is within a second threshold range.

The refrigerant state determination unit 93 also determines whether the refrigerant pressure at the outlet of the evaporator 50 is lower than atmospheric pressure or is atmospheric pressure, based on the refrigerant pressure (Pout3) at the outlet of the evaporator 50.

The refrigerant state adjustment unit 94 adjusts the opening of the expansion unit 40 and the amount of heat exchange in the evaporator 50 based on the judgment of the refrigerant state judgment unit 93. In other words, the refrigerant state adjustment unit 94 outputs a signal to the output unit 75 to adjust the opening of the expansion unit 40 and the amount of heat exchange in the evaporator 50 based on the judgment of the refrigerant state judgment unit 93. Here, the amount of heat exchange in the evaporator 50 is adjusted, for example, by adjusting the flow rate of the fluid supplied from the fluid supply pipe 51 to the evaporator 50.

The heat exchange amount calculation unit 95 calculates the amount of heat exchange in the evaporator 50. Specifically, the heat exchange amount calculation unit 95 calculates the amount of heat exchange Qeff in the evaporator 50 based on the temperature of the fluid supplied to the evaporator 50 (Tin4), the temperature of the fluid discharged from the evaporator 50 (Tout4), and the flow rate of the fluid passing through the evaporator 50.

The flow rate of the fluid passing through the evaporator 50 is detected, for example, by a flow meter (not shown) provided in the fluid discharge pipe 52. The flow rate of the fluid passing through the evaporator 50 may also be calculated, for example, from the differential pressure between the fluid pressure at the inlet of the evaporator 50 and the fluid pressure at the outlet of the evaporator 50. The flow rate of the fluid passing through the evaporator 50 may also be calculated, for example, based on the power of a fan or pump that pressurizes the fluid to the fluid supply pipe 51.

The heat exchange amount determination unit 96 determines whether the heat exchange amount calculated by the heat exchange amount calculation unit 95 is equal to or less than the heat exchange amount allowable value Qlimit in the evaporator 50.

The heat exchange amount adjustment unit 97 adjusts the amount of heat exchange in the evaporator 50 based on the judgment of the heat exchange amount judgment unit 96. In other words, the heat exchange amount adjustment unit 97 outputs a signal to the output unit 75 to adjust the amount of heat exchange in the evaporator 50 based on the judgment of the heat exchange amount judgment unit 96. Here, the amount of heat exchange in the evaporator 50 is adjusted, for example, by adjusting the flow rate of the fluid supplied to the evaporator 50 from the fluid supply pipe 51.

The output unit 75 outputs the control signal output from the calculation unit 90, for example, to a flow rate control valve 51a provided in the fluid supply pipe 51. The output unit 75 also outputs the control signal output from the calculation unit 90, for example, to the expansion unit 40.

Here, the processing performed by the control device 60 described above is realized, for example, by a computer device.

(Control related to adjustment of the state of the refrigerant at the outlet of the evaporator 50)
Next, the operation of maintaining high cycle performance by adjusting the state of the refrigerant at the outlet of the evaporator 50 in the steam generating device 1 will be described.

Figure 8 is a flow chart explaining the operation for adjusting the state of the refrigerant at the outlet of the evaporator 50 in the steam generating device 1 of the embodiment.

When an input signal for changing the operating state is input to the output unit 75, for example, the refrigerant state adjustment unit 94 outputs a signal for adjusting the opening degree of the expansion unit 40 to the output unit 75 (step S140). The output unit 75 then outputs the signal to the expansion unit 40. This adjusts the opening degree of the expansion unit 40.

The adjustment of the expansion section 40 is also performed, for example, if the answer is Yes in step S141, if the answer is No in step S147, or after the processing of step S149, as described below.

Next, the refrigerant state determination unit 93 determines whether the refrigerant pressure at the outlet of the evaporator 50 is lower than atmospheric pressure based on the refrigerant pressure (Pout3) at the outlet of the evaporator 50 (step S141).

If it is determined in step S141 that the refrigerant pressure at the outlet of the evaporator 50 is lower than atmospheric pressure (Yes in step S141), the refrigerant state adjustment unit 94 executes the process of step S140.

If it is determined in step S141 that the refrigerant pressure at the outlet of the evaporator 50 is not lower than atmospheric pressure, i.e., if it is determined that the refrigerant pressure at the outlet of the evaporator 50 is equal to or higher than atmospheric pressure (No in step S141), the refrigerant state determination unit 93 determines whether the refrigerant pressure at the outlet of the evaporator 50 is atmospheric pressure or not based on the refrigerant pressure at the outlet of the evaporator 50 (Pout3) (step S142).

If it is determined in step S142 that the refrigerant pressure at the outlet of the evaporator 50 is atmospheric pressure (Yes in step S142), the refrigerant state determination unit 93 determines whether the value of the state parameter identified by the refrigerant state determination unit 92 is within the threshold range based on the results of the calculations by the refrigerant state quantity calculation unit 91 described above (steps S130-S132: see Figure 7) and the data from the refrigerant state storage unit 81 (step S143).

Here, if the state parameter is a first state parameter, the threshold is a first threshold. Also, if the state parameter is a second state parameter, the threshold is a second threshold. These thresholds are stored in the refrigerant state storage unit 81.

If it is determined in step S143 that the value of the state parameter is not within the threshold range (No in step S143), the refrigerant state adjustment unit 94 outputs a signal to adjust the heat exchange amount in the evaporator 50 to the output unit 75 (step S144). The output unit 75 then outputs the signal to, for example, the flow rate adjustment valve 51a provided in the fluid supply pipe 51. This adjusts the flow rate adjustment valve 51a.

Here, if the enthalpy ratio (ΔH/Hsat), which is the first state parameter, falls below the first threshold value, the flow rate of the fluid supplied to the evaporator 50 is increased. Also, if the enthalpy ratio (ΔH/Hsat), which is the first state parameter, exceeds the first threshold value, the flow rate of the fluid supplied to the evaporator 50 is decreased.

When the second state parameter, wetness, exceeds a second threshold, the flow rate of the fluid supplied to the evaporator 50 is increased. When the second state parameter, superheat, exceeds a second threshold, the flow rate of the fluid supplied to the evaporator 50 is decreased.

If it is determined in step S143 that the value of the state parameter is within the threshold range (Yes in step S143), the heat exchange amount determination unit 96 determines whether the heat exchange amount Qeff is equal to or less than the heat exchange amount allowable value Qlimit based on the heat exchange amount Qeff calculated by the heat exchange amount calculation unit 95 and the heat exchange amount allowable value Qlimit stored in the heat exchange amount memory unit 82 (step S145).

If it is determined in step S145 that the heat exchange amount Qeff is equal to or less than the heat exchange amount allowable value Qlimit (Yes in step S145), the operation ends.

If it is determined in step S145 that the heat exchange amount Qeff is not equal to or less than the heat exchange amount allowable value Qlimit, i.e., if it is determined that the heat exchange amount Qeff exceeds the heat exchange amount allowable value Qlimit (No in step S145), the heat exchange amount adjustment unit 97 outputs a signal to adjust the heat exchange amount in the evaporator 50 to the output unit 75 (step S146). Then, the output unit 75 outputs the signal to, for example, the flow rate adjustment valve 51a provided in the fluid supply pipe 51. This adjusts the flow rate adjustment valve 51a.

In this case, the heat exchange amount adjustment unit 97 outputs a signal to the output unit 75 to reduce the flow rate of the fluid supplied to the evaporator 50.

After processing step S146, execute processing step S143 again.

If it is determined in step S142 that the refrigerant pressure at the outlet of the evaporator 50 is not atmospheric pressure (No in step S142), the refrigerant state determination unit 93 determines, similarly to step S143, whether the value of the state parameter identified by the refrigerant state identification unit 92 is within the threshold range based on the result of the calculation by the refrigerant state quantity calculation unit 91 (step S147).

Here, if it is determined in step S142 that the refrigerant pressure at the outlet of the evaporator 50 is not atmospheric pressure, this means that the refrigerant pressure at the outlet of the evaporator 50 exceeds atmospheric pressure.

When it is determined in step S147 that the value of the state parameter is not within the threshold range (No in step S147), the process of step S140 is executed. In step S140, the opening degree of the expansion section 40 is adjusted so that the value of the state parameter is within the threshold range.

If it is determined in step S147 that the value of the state parameter is within the threshold range (Yes in step S147), the heat exchange amount determination unit 96 determines whether the heat exchange amount Qeff is less than or equal to the heat exchange amount tolerance Qlimit based on the heat exchange amount Qeff calculated by the heat exchange amount calculation unit 95 and the heat exchange amount tolerance Qlimit stored in the heat exchange amount memory unit 82 (step S148).

If it is determined in step S148 that the heat exchange amount Qeff is equal to or less than the heat exchange amount allowable value Qlimit (Yes in step S148), the operation ends.

If it is determined in step S148 that the heat exchange amount Qeff is not equal to or less than the heat exchange amount allowable value Qlimit (No in step S148), the heat exchange amount adjustment unit 97 outputs a signal to adjust the heat exchange amount in the evaporator 50 to the output unit 75 (step S149). The output unit 75 then outputs the signal to, for example, the flow rate adjustment valve 51a provided in the fluid supply pipe 51. This adjusts the flow rate adjustment valve 51a.

In this case, the heat exchange amount adjustment unit 97 outputs a signal to the output unit 75 to reduce the flow rate of the fluid supplied to the evaporator 50.

After processing step S149, execute processing step S140.

As described above, according to the embodiment of the steam generating device 1, the state of the refrigerant at the outlet of the evaporator 50 can be determined by calculating the state quantity of the refrigerant at the outlet of the evaporator 50. Furthermore, according to the steam generating device 1, high cycle performance can be maintained by adjusting the state of the refrigerant at the outlet of the evaporator 50.

Here, in the steam generating device 1 of the above embodiment, the installation configuration of each device is not particularly limited, but an example of the installation configuration of each device is shown.

Each device of the steam generating device 1 may be installed, for example, at approximately the same height position. Also, the heat exchange section 53 of the evaporator 50 may be installed, for example, at a higher position than the other devices. Note that the heat exchange section 53 of the evaporator 50 is a section where heat exchange occurs between the fluid introduced into the evaporator 50 and the refrigerant flowing through the evaporator 50. Also, the height position is the height position in the vertical direction.

Here, we will explain the case where the heat exchange section 53 of the evaporator 50 is installed at a higher position than other equipment.

Figure 9 is a schematic diagram showing the arrangement of the steam generating device 1 of the embodiment when the heat exchange section 53 of the evaporator 50 is installed at a higher position than the other devices. In Figure 9, only the heat exchange section 53 of the evaporator 50 is shown. Figure 10 is a p-h (pressure-enthalpy) diagram of the heat pump system 5 when the steam generating device 1 of the embodiment is installed as shown in Figure 9. Note that in Figure 10, the horizontal axis, vertical axis, and isotherms are the same as those in the p-h diagram shown in Figure 2.

As shown in FIG. 9, the heat exchange section 53 of the evaporator 50 is installed at a higher position than other equipment, for example. Here, the evaporator 50 itself may be installed, for example, on the foundation (base) on which other equipment is installed. In FIG. 9, an example is shown in which the expansion section 40 is installed at a position slightly lower than the heat exchange section 53 of the evaporator 50, and the compressor 10, radiator 20, and heat exchanger 30 are installed at a lower position than the expansion section 40. Also, in FIG. 9, the compressor 10, radiator 20, and heat exchanger 30 are installed at the same height.

The heat exchange section 53 of the evaporator 50 only needs to be installed at a position at least higher than the heat exchanger 30. Equipment other than the heat exchange section 53 of the evaporator 50 may be installed at any position lower than the heat exchange section 53 of the evaporator 50, taking into consideration maintainability, location conditions, etc.

As shown in FIG. 9, the expansion section 40 is preferably installed at a high position close to the heat exchange section 53 of the evaporator 50. By installing the expansion section 40 at a height close to the heat exchange section 53 of the evaporator 50, the pressure difference between before and after the expansion section 40 can be used to supply the refrigerant to the evaporator 50 without pumping it with a pump. This eliminates the need for power to pump the refrigerant from the expansion section 40 to the evaporator 50, improving the COP.

In FIG. 9, the vertical height position of the piping at the outlet of the heat exchange section 53 of the evaporator 50 is indicated as Z1, and the vertical height position of the piping that introduces the refrigerant to the heat exchanger 30 is indicated as Z2.

When the refrigerant descends through the pipe from height position Z1 to height position Z2, the difference in potential energy changes into pressure energy. Regarding velocity energy, the flow rate differs depending on the pipe diameter and also on the equipment. Therefore, here we will explain the change from potential energy to pressure energy, which is the main cause of energy change.

Here, assuming that the density of the refrigerant is ρ and the gravitational acceleration is g, the pressure change ΔP due to the head difference between the height position Z1 and the height position Z2 is expressed by the following equation.
ΔP=ρ×g×(Z1-Z2)

The pressure loss between height position Z1 and height position Z2 is reduced by the pressure change ΔP due to the head difference. If the pressure loss from height position Z1 to height position Z2 is smaller than the head difference, the power required for pressurization in the compressor 10 can be reduced. As shown in FIG. 10, the refrigerant pressure at the inlet of the compressor 10 increases due to the head difference from refrigerant pressure Pz1 at height position Z1 at the outlet of the heat exchange section 53 of the evaporator 50 to refrigerant pressure Pz2 at height position Z2 at the inlet of the heat exchanger 30 (state A1).

That is, as can be seen from a comparison of the p-h diagram in FIG. 2, in which the various devices of the steam generating device 1 are installed at the same height, with the p-h diagram in FIG. 10, by installing the heat exchange section 53 of the evaporator 50 at a higher position than the other devices, the refrigerant pressure at the inlet of the compressor 10 (state A1) increases. Therefore, when pressurizing to state B, it is possible to reduce the power required in the compressor 10 equivalent to the increased pressure. This makes it possible to improve the COP.

Here, for example, by increasing the inner diameter of the pipe through which the refrigerant flows between the evaporator 50 and the heat exchanger 30 and reducing the pressure loss in the pipe, the potential energy difference can be utilized to improve the COP as described above.

Other Embodiments
Here, Fig. 11 is a system diagram of a steam generator 2 having another configuration of the embodiment. In the following embodiment, the same components as those of the steam generator 1 of the embodiment are denoted by the same reference numerals, and duplicated explanations are omitted or simplified.

As shown in FIG. 11, an evaporator 160 may be provided downstream of the evaporator 50. In other words, the evaporator 160 may be provided between the evaporator 50 and the heat exchanger 30. Note that the downstream side means the downstream side in the direction in which the refrigerant flows.

The evaporator 160, like the evaporator 50, evaporates the refrigerant remaining as a liquid by heat exchange between the refrigerant and a second fluid introduced from the outside. The fluid supply pipe 161 supplies the second fluid, which imparts heat to the refrigerant flowing through the piping inside the evaporator 160, into the evaporator 160. The fluid discharge pipe 162 discharges the second fluid, which has heated the refrigerant, from the evaporator 160. The temperature of the refrigerant discharged from the fluid discharge pipe 162 is lower than the temperature of the refrigerant supplied from the fluid supply pipe 161.

The fluid supply pipe 161 is also provided with a flow rate adjustment valve 161a. The flow rate adjustment valve 161a may also be provided in the fluid discharge pipe 162.

Here, the second fluid introduced into the evaporator 160 may be any fluid having a higher temperature than the refrigerant flowing through the evaporator 160. In other words, the second fluid introduced into the evaporator 160 may be any fluid having a heat quantity that causes the refrigerant to evaporate in the evaporator 160. In addition, the temperature of the second fluid is higher than the temperature of the fluid supplied from the fluid supply pipe 51 to the evaporator 50.

This second fluid is not particularly limited, but may be, for example, drain water discharged from a factory. The second fluid is introduced into the fluid supply pipe 161 from the outside by a pump or other pressure-feeding device (not shown).

In the steam generating device 2, for example, a portion of the refrigerant is evaporated in the evaporator 50. Then, in the evaporator 160, the refrigerant remaining as a liquid is evaporated by heat exchange with a second fluid.

Here, the outlet of the evaporator 50 in the embodiment described above corresponds to the outlet of the evaporator 160 in the steam generating device 2 shown in FIG. 11. Therefore, in the steam generating device 2 shown in FIG. 11, the refrigerant state quantity calculation unit 91 calculates the state quantity of the refrigerant at the outlet of the evaporator 160. The refrigerant state determination unit 92 determines the state of the refrigerant at the outlet of the evaporator 160 based on the state quantity of the refrigerant calculated by the refrigerant state quantity calculation unit 91, the refrigerant pressure at the outlet of the evaporator 160, and the data of the refrigerant state storage unit 81.

The first state parameter, first threshold, second state parameter, and second threshold used in the refrigerant state determination unit 93 are the same as those in the embodiment described above.

The refrigerant state adjustment unit 94 adjusts the opening of the expansion section 40 and the amount of heat exchange in the evaporator 160 based on the judgment of the refrigerant state judgment unit 93. Note that when adjusting the amount of heat exchange in the evaporator 160, the refrigerant state adjustment unit 94 may also adjust the amount of heat exchange in the evaporator 50.

In addition, when adjusting the heat exchange amount in the evaporator 160 based on the judgment of the heat exchange amount judgment unit 96, the heat exchange amount adjustment unit 97 may also adjust the heat exchange amount in the evaporator 50.

By providing the evaporator 160 in the steam generating device 2, the amount of heat exchange in the evaporator 50 can be reduced. For example, if air is used as the fluid in the evaporator 50, the power of the fan that supplies air to the evaporator 50 can be reduced. This can improve the COP.

In addition, when air is used as the fluid in the evaporator 50 and drain water discharged from a factory or the like is used as the second fluid in the evaporator 160, the size of the evaporator 50 can be made smaller than the size of the evaporator 50 when the evaporator 50 alone exchanges heat with air. This makes it possible to reduce the installation area of the evaporator 50.

Here, FIG. 12 is a system diagram of a steam generating device 3 having another configuration of the embodiment.

As shown in FIG. 12, the fluid supply pipe 51 may be provided with a heat exchanger 170. The heat exchanger 170 includes a fluid supply pipe 171 that supplies the second fluid to the heat exchanger 170, and a fluid discharge pipe 172 that discharges the second fluid from the heat exchanger 170.

The fluid supply pipe 171 is equipped with a flow rate control valve 171a that adjusts the flow rate of the second fluid supplied to the heat exchanger 170.

The temperature of the second fluid is higher than the temperature of the fluid flowing through the fluid supply pipe 51. The second fluid is not particularly limited, but may be, for example, drain water discharged from a factory, etc.

The fluid flowing through the fluid supply pipe 51 is heated by heat exchange with the second fluid. The fluid heated in the heat exchanger 170 is then supplied to the evaporator 50.

Here, for example, when adjusting the amount of heat exchange in the evaporator 50 based on the judgment of the refrigerant state judgment unit 93, the refrigerant state adjustment unit 94 may adjust the flow rate of the fluid supplied from the fluid supply pipe 51 to the evaporator 50, and may also control the flow rate adjustment valve 171a to adjust the flow rate of the second fluid.

In addition, when adjusting the heat exchange amount in the evaporator 50 based on the judgment of the heat exchange amount judgment unit 96, the heat exchange amount adjustment unit 97 may adjust the flow rate of the fluid supplied to the evaporator 50 from the fluid supply pipe 51, and may also control the flow rate adjustment valve 171a to adjust the flow rate of the second fluid.

By providing a heat exchanger 170 in the steam generating device 3, the evaporation and heating of the refrigerant in the evaporator 50 can be promoted. This reduces the power required by the compressor 10, improving the COP.

According to the embodiment described above, in a heat pump cycle, it is possible to maintain high cycle performance by adjusting the state of the refrigerant at the outlet of the evaporator.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

1, 2, 3...steam generating device, 5...heat pump system, 10...compressor, 11...drive device, 20...radiator, 21...water supply pipe, 22...steam exhaust pipe, 30, 170...heat exchanger, 40...expansion section, 50...evaporator, 51, 161, 171...fluid supply pipe, 51a, 161a, 171a...flow control valve, 52, 162, 172...fluid exhaust pipe, 53...heat exchange section, 60...control device, 70...input section, 75...output section, 80...memory section, 81...refrigerant state memory section, 82...heat exchange amount Memory unit, 90...calculation unit, 91...refrigerant state quantity calculation unit, 92...refrigerant state determination unit, 93...refrigerant state determination unit, 94...refrigerant state adjustment unit, 95...heat exchange amount calculation unit, 96...heat exchange amount determination unit, 97...heat exchange amount adjustment unit, 100...detection unit, 101, 103, 105, 108, 109...temperature detection unit, 102, 104, 106, 107...pressure detection unit, 110...saturated vapor line, 111...saturated liquid line, 112...critical point, 120...wet vapor region, 121...superheated vapor region, 160...evaporator.

Claims (11)

a heat pump system in which a refrigerant is circulated through a compressor, a radiator, a heat exchanger, an expansion section, an evaporator, and the heat exchanger in this order, and in which a low-pressure side refrigerant that has passed through the evaporator is heat-exchanged with a high-pressure side refrigerant that has passed through the radiator in the heat exchanger;
a fluid supply unit that supplies a fluid to the evaporator to impart heat to the refrigerant in the evaporator;
a water supply unit that supplies water to the radiator for generating steam by heat exchange with the refrigerant in the radiator ,
A steam generating device that adjusts at least one of an opening degree of the expansion section and a heat exchange amount in the evaporator based on a state quantity of a refrigerant at an outlet of the evaporator ,
a heat exchange amount calculation unit that calculates a heat exchange amount in the evaporator;
a heat exchange amount determination unit that determines whether the heat exchange amount calculated by the heat exchange amount calculation unit is equal to or less than a heat exchange amount allowable value in the evaporator;
a heat exchange amount adjustment unit that adjusts the amount of heat exchange in the evaporator based on the determination by the heat exchange amount determination unit;
A steam generating device comprising: a refrigerant state quantity calculation unit that calculates a state quantity of the refrigerant at an outlet of the evaporator;
a refrigerant state determination unit that determines a state of the refrigerant at an outlet of the evaporator based on the state quantity of the refrigerant calculated by the refrigerant state quantity calculation unit;
a refrigerant state determination unit that determines whether the state of the refrigerant identified by the refrigerant state determination unit is within a predetermined state range;
The steam generating device according to claim 1 , further comprising a refrigerant state adjusting unit that adjusts at least one of an opening degree of the expansion unit and an amount of heat exchange in the evaporator based on a determination by the refrigerant state determining unit. 3. The steam generating device according to claim 2, wherein the refrigerant state quantity calculation unit calculates a state quantity of the refrigerant at the outlet of the evaporator based on a pressure of the refrigerant at the outlet of the evaporator, a state quantity of the high-pressure side refrigerant at the inlet and outlet of the high-pressure side refrigerant of the heat exchanger, and a state quantity of the low-pressure side refrigerant at the outlet of the low-pressure side refrigerant of the heat exchanger . a heat pump system in which a refrigerant is circulated through a compressor, a radiator, a heat exchanger, an expansion section, an evaporator, and the heat exchanger in this order, and in which a low-pressure side refrigerant that has passed through the evaporator and a high-pressure side refrigerant that has passed through the radiator are heat-exchanged in the heat exchanger;
a fluid supply unit that supplies a fluid to the evaporator to impart heat to the refrigerant in the evaporator;
a water supply unit that supplies water to the radiator for generating steam by heat exchange with a refrigerant in the radiator;
a refrigerant state quantity calculation unit that calculates a state quantity of the refrigerant at an outlet of the evaporator;
a refrigerant state determination unit that determines a state of the refrigerant at an outlet of the evaporator based on the state quantity of the refrigerant calculated by the refrigerant state quantity calculation unit;
a refrigerant state determination unit that determines whether the state of the refrigerant identified by the refrigerant state determination unit is within a predetermined state range;
a refrigerant state adjusting unit that adjusts at least one of an opening degree of the expansion unit and an amount of heat exchange in the evaporator based on a determination by the refrigerant state determining unit;
Equipped with
a refrigerant state quantity calculation unit that calculates a state quantity of the refrigerant at the outlet of the evaporator based on the pressure of the refrigerant at the outlet of the evaporator, a state quantity of the high-pressure side refrigerant at the inlet and outlet of the high-pressure side refrigerant of the heat exchanger, and a state quantity of the low-pressure side refrigerant at the outlet of the low-pressure side refrigerant of the heat exchanger. The steam generating device according to any one of claims 2 to 4, characterized in that the refrigerant state identification unit identifies the state of the refrigerant at the outlet of the evaporator by an enthalpy ratio (ΔH/Hsat) which is the ratio of a difference (ΔH) between a first enthalpy of the refrigerant at the outlet of the evaporator and a second enthalpy (Hsat) at a point where an isobar of the refrigerant pressure at the outlet of the evaporator intersects with a saturated vapor line, and the second enthalpy (Hsat). The steam generating device according to any one of claims 2 to 4, characterized in that the refrigerant state determination unit determines the state of the refrigerant at the outlet of the evaporator based on the wetness and superheat of the refrigerant at the outlet of the evaporator. The evaporator includes a heat exchange portion where a refrigerant and the fluid exchange heat with each other,
7. The steam generating device according to claim 1, wherein the heat exchange section is disposed at a higher position than each of the devices constituting the heat pump system. The steam generating device according to claim 7, characterized in that the expansion section is installed in a position close to the heat exchange section of the evaporator. The steam generating device according to any one of claims 1 to 8, characterized in that the normal boiling point of the refrigerant circulating in the heat pump system is lower than the temperature of the fluid supplied to the evaporator. The steam generating device according to any one of claims 1 to 8, characterized in that the refrigerant circulating in the heat pump system is a refrigerant that does not have a normal boiling point. The steam generating device according to any one of claims 1 to 10, characterized in that the pressure of the refrigerant circulating in the heat pump system is equal to or higher than atmospheric pressure.

Images