Steam-generating heat pump device, method for controlling steam-generating heat pump device, and program for calculating flow rate of separated circulating water

Abstract

Provided are: a steam-generating heat pump device in which the flow rate of separated circulating water can be determined; a method for controlling the steam-generating heat pump device; and a program for calculating the flow rate of separated circulating water. A steam-generating heat pump device 10 includes a steam-generating part 14 and a heat pump part 12. The steam-generating part 14 comprises a condenser 22 and a gas-liquid separator 34 and includes a thermosyphon circuit where confluence water formed by the confluence of supply water supplied from a feedwater pump 38 with separated circulating water, which has been separated by the gas-liquid separator 34, at a confluence point J is boiled in the condenser 22 and returned to the gas-liquid separator 34. The heat pump part 12 vaporizes a refrigerant with heat collected from heat source water, compresses the refrigerant, and boils the confluence water with the refrigerant in the condenser 22. A control unit 16 calculates a flow rate Mc of the separated circulating water on the basis of a weighted-mean equation from a temperature Tc of the separated circulating water before the confluence point J of the separated circulating water, a temperature Tp0 of the supply water before the confluence point J, a flow rate Mp of the supply water, and a temperature Tj of the confluence water.

Description

Steam-generating heat pump apparatus, control method for steam-generating heat pump apparatus, and program for calculating separated circulating water flow rate

[0001] The present invention relates to a steam-generating heat pump apparatus, a control method for a steam-generating heat pump apparatus, and a program for calculating a separated circulating water flow rate.

[0002] As one type of steam generator, there is a steam-generating heat pump apparatus that generates steam by recovering heat from waste warm water such as factory wastewater and used cooling water. In the steam-generating heat pump apparatus, an evaporator of a heat pump unit functions as a waste heat recoverer, where heat is recovered from a heat source warm water by a refrigerant, and the recovered heat is used to heat water to be heated in a condenser to generate water vapor. Therefore, compared with combustion-type steam generators that generate water vapor using boiler equipment or the like, the present apparatus has advantages such as lower running costs and reduced CO ２ emissions.

[0003] The steam-generating heat pump apparatus disclosed in Japanese Patent Application Laid-Open No. 2020-41724 includes a heat pump unit that recovers heat from heat source water, and a steam generation unit that performs heat exchange between the refrigerant of the heat pump unit and a condenser. In the steam generation unit, supply water supplied from a water supply pump is boiled in the condenser to be in a gas-liquid mixed state, and further separated into steam and liquid by a gas-liquid separator. The separated liquid merges with the supply water and then returns to the condenser, forming a thermosiphon circuit to circulate water. According to the thermosiphon circuit, heat can be efficiently transported while utilizing gravity.

[0004] Japanese Patent Application Laid-Open No. 2020-41724

[0005] When water is heated and boiled in a condenser, it is preferable that the water outlet of the condenser is in a gas-liquid two-phase state with an appropriate gas phase ratio (also called quality or dryness) while maintaining the liquid amount at a certain level or higher. This can prevent impurities (e.g., chloride ions) in the supply water from precipitating, thereby preventing the occurrence of corrosion starting from the impurities.

[0006] The gas phase ratio can be determined from the flow rate of the combined water after the feed water and separated circulating water have merged. While the flow rate of the feed water can be controlled by the rotation speed of the supply pump, a dedicated flow meter is required to measure the flow rate of the separated circulating water. However, such flow meters are undesirable from the standpoint of increased cost, pressure loss in the thermosiphon, layout limitations, and heat resistance limitations. Furthermore, the flow rate of the separated circulating water is difficult to calculate because it depends on the average density in the condenser and the pressure loss in the flow path.

[0007] Therefore, conventionally, the feedwater pump was controlled to maintain a constant liquid level in the steam separator, thereby optimizing the gas-phase ratio at the condenser outlet. However, when disturbances such as changes in feedwater temperature occur, the ratio does not become as expected, limiting the optimal operating conditions for the refrigeration system.

[0008] The present invention has been made in view of the above problems, and aims to provide a steam generation heat pump device capable of determining the flow rate of separated circulating water, which is a prerequisite for stably achieving a suitable gas phase ratio, a control method for the steam generation heat pump device, and a program for calculating the flow rate of separated circulating water.

[0009] To solve the above-mentioned problems and achieve the objective, the steam generation heat pump device according to the present invention comprises a control unit, a steam generation unit comprising a thermosiphon circuit including a condenser and a gas-liquid separator, in which the separated circulating water of the liquid phase separated by the gas-liquid separator and the separated blowdown water to be blown down, the separated circulating water and the supply water supplied from the water supply pump merge at a confluence point, the merged water is boiled in the condenser and supplied to the gas-liquid separator, and a heat pump unit which evaporates and compresses a refrigerant with heat recovered from the heat source water, and the refrigerant is used to boil the merged water in the condenser, wherein the control unit calculates the flow rate of the separated circulating water based on a weighted average formula from the temperature of the separated circulating water before the confluence point, the temperature of the supply water before the confluence point, the flow rate of the supply water before the confluence point, and the temperature of the merged water.

[0010] Furthermore, the control method for a steam generation heat pump device according to the present invention comprises a control unit, a steam generation unit comprising a thermosiphon circuit including a condenser and a gas-liquid separator, wherein the separated circulating water of the liquid phase separated by the gas-liquid separator and the separated blowdown water to be blown down, the separated circulating water and the supply water supplied from the water supply pump, are combined at a confluence point, the combined water is boiled in the condenser and supplied to the gas-liquid separator, and a heat pump unit that evaporates and compresses a refrigerant with heat recovered from the heat source water, and the combined water is boiled in the condenser by the refrigerant, wherein the control unit controls the separated circulating water before the confluence point of the separated circulating water The method is characterized by reading or determining the circulating water temperature, the supply water temperature before the confluence point of the supply water, the supply water flow rate before the confluence point of the supply water, and the confluence water temperature from sensors; calculating the separate circulating water flow rate of the separate circulating water based on a weighted average formula from the separate circulating water temperature, the supply water temperature, the supply water flow rate, and the confluence water temperature; calculating the gas phase ratio of the confluence water boiled in the condenser from the supply water flow rate, the separate circulating water flow rate, the amount of liquid level change in the gas-liquid separator, and the separate blowdown water flow rate of the separate blowdown water; and controlling at least one of the supply water flow rate and the refrigerant flow rate of the supply water so that the gas phase ratio is within a predetermined range.

[0011] Furthermore, the steam generation heat pump unit comprises a control unit including a memory unit, a thermosiphon circuit including a condenser and a gas-liquid separator, where the separated circulating water of the liquid phase separated by the gas-liquid separator and the separated blowdown water to be blown down are combined at a confluence point, the combined water is boiled in the condenser and supplied to the gas-liquid separator, and the steam generation heat pump unit evaporates and compresses a refrigerant with heat recovered from the heat source water, and the combined water is boiled in the condenser. A program for calculating the flow rate of separated circulating water in a pump device, which is read from the storage unit and executed by the control unit, is characterized in that the control unit is made to perform the following steps: read or determine the temperature of the separated circulating water before the confluence point of the separated circulating water, the temperature of the supply water before the confluence point of the supply water, the flow rate of the supply water before the confluence point of the supply water, and the temperature of the confluence water from sensors; and calculate the flow rate of the separated circulating water based on a weighted average formula from the temperature of the separated circulating water, the temperature of the supply water, the flow rate of the supply water, and the temperature of the confluence water.

[0012] According to the present invention, the flow rate of separated circulating water can be determined without using a flow meter.

[0013] Figure 1 is a circuit diagram showing the configuration of a steam generation heat pump device according to an embodiment of the present invention. Figure 2 is a flowchart of the control method for the steam generation heat pump device, which is executed by the control unit after reading the program. Figure 3 is a flowchart showing the detailed control of the supply water flow rate Mp in step 7. Figure 4 is a schematic circuit diagram showing a part of the steam generation heat pump device when performing calibration processing of the volumetric efficiency η.

[0014] The following describes in detail, with reference to the drawings, embodiments of the steam generation heat pump device, the control method for the steam generation heat pump device, and the program for calculating the separated circulating water flow rate according to the present invention. However, the present invention is not limited to these embodiments.

[0015] Figure 1 is a circuit diagram showing the configuration of a steam generation heat pump device 10 according to an embodiment of the present invention. In Figure 1, dashed lines represent electrical signals, medium-thick lines represent refrigerant lines, and other solid lines represent water lines. As shown in Figure 1, the steam generation heat pump device 10 has a heat pump unit 12, a steam generation unit 14, and a control unit 16. In Figure 1, the part below the dashed line excluding the control unit 16 is the heat pump unit 12, and the part above the dashed line corresponds to the steam generation unit 14. The condenser 22 and subcooler 24 on the dashed line are shared by the heat pump unit 12 and the steam generation unit 14.

[0016] The heat pump unit 12 comprises a heat pump cycle that evaporates and compresses a refrigerant using heat recovered from heat source water, boils the combined water in a condenser 22 using the refrigerant, and preheats the water to be heated in a subcooler 24. Specifically, the heat pump unit 12 includes an evaporator 18 that evaporates a low-pressure refrigerant using heat recovered from waste hot water (heat source water) such as factory wastewater, a compressor 20 that compresses the low-pressure refrigerant introduced from the evaporator 18 into a high-pressure refrigerant, a condenser 22 that condenses the high-pressure refrigerant compressed by the compressor 20 to heat and boil the water to be heated, a subcooler 24 that subcools the refrigerant condensed in the condenser 22 to preheat the water to be heated, and a first expansion valve 26 and a second expansion valve 28 that depressurize and expand the refrigerant introduced from the subcooler 24 and lead it to the evaporator 18, and these are connected by a refrigerant circulation path. The compressor 20 is, for example, a scroll type and is a two-stage compressor with a series configuration of a first compressor 20a and a second compressor 20b. A gas-liquid separator 30 is provided between the first expansion valve 26 and the second expansion valve 28, and the separated gas phase portion is supplied between the first compressor 20a and the second compressor 20b, forming a two-stage compression cycle. The heat pump unit 12 in this embodiment is a two-stage compression, two-stage expansion cycle type, but it may also be a two-stage compression, one-stage expansion cycle type or a single-stage cycle type.

[0017] In addition to the condenser 22 and subcooler 24 described above, the steam generation unit 14 includes a gas-liquid separator 34 and a heat recovery exchanger 36. In the steam generation unit 14, the water to be heated supplied from the feedwater pump 38 undergoes heat recovery in the heat recovery exchanger 36, and is further preheated by heat exchange with the refrigerant in the subcooler 24 before being supplied to the condenser 22. In the condenser 22, the water to be heated is boiled by heat exchange with the refrigerant. At this time, the control unit 16 controls the gas-phase ratio (also called quality or dryness) Q of the boiled water to be heated in the condenser 22 to an appropriate value of less than 1.0. This control will be described later.

[0018] The heated water, which boils in the condenser 22, is supplied to the gas-liquid separator 34 where it is separated into a gas phase and a liquid phase. The steam in the gas phase is output from the output pipeline via the control valve 40 and supplied to the user's heat process. A portion of the liquid phase separated in the gas-liquid separator 34 is blown down for water quality control. This blowdown passes through the heat recovery exchanger 36 and exchanges heat with the heated water supplied from the feedwater pump 38.

[0019] The liquid phase separated by the gas-liquid separator 34, excluding the blowdown portion, is combined with the heated water from the feedwater pump 38 at confluence point J and supplied to the condenser 22. In other words, as shown by the circular arrow, the heated water circulates between the condenser 22 and the gas-liquid separator 34, forming a thermosiphon circuit. The condenser 22 and the gas-liquid separator 34, which are components of the thermosiphon circuit, are vertically oriented (see Figure 4).

[0020] Hereinafter, the water to be heated supplied from the water supply pump 38 will be referred to as the supply water, and its flow rate will be the supply water flow rate Mp. Of the liquid phase separated by the gas-liquid separator 34, the portion that circulates in the thermosiphon circuit upon reaching the confluence point J will be referred to as the separated circulating water, and its flow rate will be the separated circulating water flow rate Mc. The portion that is blown down will be referred to as the separated blowdown water, and its flow rate will be the separated blowdown water flow rate Mb. The water to be heated that merges at the confluence point J will be referred to as the merged water, and its flow rate will be the merged water flow rate Mj.

[0021] In the supply water pipeline, a temperature sensor for measuring temperature Tp1 is provided at the inlet of the heat recovery exchanger 36, and a temperature sensor for measuring temperature Tp2 is provided at the outlet. A temperature sensor for measuring temperature Tp0 is provided on the output side of the subcooler 24, just before the confluence point J. In the separation blowdown water pipeline, a temperature sensor for measuring temperature Tb is provided at the outlet of the heat recovery exchanger 36. In the separation circulating water pipeline, a temperature sensor for measuring temperature Tc is provided just before the confluence point J. Temperature Tc corresponds to the separation circulating water temperature and the separation blowdown water temperature. In the confluence water pipeline, a sensor for measuring the confluence water temperature Tj is provided just before the condenser 22. A pressure sensor for measuring pressure Po is provided in the steam output pipeline of the gas-liquid separator 34. The gas-liquid separator 34 is equipped with a water level sensor for measuring the liquid level H. The measured values ​​of each of these sensors are configured to be readable by the control unit 16. Although the heat pump unit 12 is also equipped with necessary sensors as appropriate, their explanation is omitted here.

[0022] The control unit 16 controls the entire steam generation heat pump device 10. The control unit 16 incorporates a processor, which is composed of hardware such as a general-purpose processor like a CPU (Central Processing Unit) or a dedicated integrated circuit that performs specific functions like an FPGA (Field Programmable Gate Array), either alone or in combination. It reads the program 72 stored in the memory unit 70 and performs various calculations to operate the steam generation heat pump device 10. The program 72 may consist of a single executable file or multiple programs may be executed collaboratively.

[0023] The storage unit 70 is implemented by recording media such as EPROM (Erasable Programmable ROM), HDD (Hard Disk Drive), SSD (Solid State Drive), and removable media. Examples of removable media include disk recording media such as USB (Universal Serial Bus) memory, CD (Compact Disc), DVD (Digital Versatile Disc), and BD (Blu-ray® Disc). The storage unit 70 can store the OS (Operating System), various programs, various tables, various databases, etc. The control unit 16 may be provided integrally with the steam generation heat pump device 10, or it may be connected via communication means. The storage unit 70 and the program 72 may be built into the control unit 16, or they may be connected via communication means.

[0024] The control unit 16 can control the water supply flow rate Mp by changing the rotation speed of the water supply pump 38. The control unit 16 can control the refrigerant circulation amount by changing the rotation speed of the compressor 20. The control unit 16 can control the steam output flow rate by changing the opening degree of the control valve 40.

[0025] Figure 2 is a flowchart of the control method for the steam generation heat pump device 10, which is executed by the control unit 16 after reading the program 72. The control unit 16 is basically the main entity that executes each step. The process in Figure 2 is executed repeatedly at very short intervals.

[0026] In step S1, measured values ​​are read from each of the above sensors. In step S2, the pressure Po in the steam output pipeline is detected, and the control valve 40 is adjusted to achieve a predetermined steam temperature. By measuring the pressure Po and controlling the pressure in the steam system by adjusting the opening of the control valve 40, the output steam temperature can be controlled. The user sets the output steam temperature and operates the system.

[0027] In step S3, the supply water flow rate Mp is determined based on equation (1). Here, N is the rotational speed instructed to the water supply pump 38 at that time, Vp is the volume of the water supply pump 38, and η is the volumetric efficiency of the water supply pump 38. The volume Vp is a constant and is stored non-volatilely in the memory unit 70. The volumetric efficiency η is a variable and its value at that time is stored non-volatilely in the memory unit 70. The volumetric efficiency η is calibrated as appropriate by a method described later. The supply water flow rate Mp may also be determined by referring to a characteristic map based on the volumetric efficiency η, rather than by calculation. Since the supply water is at a low temperature, unlike the separated circulating water, it may be measured using a flow meter.

[0028] In step S4, the flow rate Mc of the separated circulating water is calculated based on equation (2). That is, the flow rate Mc of the separated circulating water is determined based on the temperature Tc of the separated circulating water before the confluence point J of the separated circulating water, the temperature Tp of the supply water before the confluence point J of the supply water (Tp = Tp0), the flow rate Mc of the supply water before the confluence point J of the supply water, and the temperature Tj of the confluence water. Note that equation (2) is obtained by modifying equation (3), which is the weighted average of the flow rate and temperature of the water before and after the confluence point J. In this way, in this embodiment, since the flow rate Mc of the separated circulating water can be determined by calculation, a flow meter in this part is unnecessary, there is no cost increase or pressure loss of the thermosiphon, and furthermore, it is not affected by layout limitations or heat resistance limitations.

[0029] In step S5, the separated blowdown water flow rate Mb is determined based on equation (4). Here, ΔTc is the temperature difference before and after the feedwater, which is the low-temperature side of the heat recovery exchanger 36, and ΔTc = Tc - Tb. ΔTh is the temperature difference before and after the separated blowdown water, which is the high-temperature side of the heat recovery exchanger 36, and ΔTh = Tp2 - Tp1. In this way, the separated blowdown water flow rate Mb can be determined from the temperature difference before and after each pipeline connected to the heat recovery exchanger 36. However, if the heat recovery exchanger 36 is omitted due to design conditions, the separated blowdown water flow rate Mb may be a design constant value or a theoretical value. In step S6, the change in the liquid level Ms in the gas-liquid separator 34 is determined based on equation (5). Here, ΔH is the change in the liquid level H of the gas-liquid separator 34 over a predetermined unit time, A is the cross-sectional area of ​​the gas-liquid separator 34, and ρw is the density of water. The gas-liquid separator 34 is columnar and its cross-sectional area A is constant regardless of its height, but if it is not columnar, the cross-sectional area A can be expressed as a function of the liquid level H.

[0030] On the other hand, the liquid level change Ms can be expressed by equation (6) from the mass balance relationship in the gas-liquid separator 34. In equation (6), the first term on the right side is the liquid supply amount flowing from the condenser 22 into the gas-liquid separator 34, the second term is the separated circulating water flow rate Mc of the liquid discharge amount flowing out of the gas-liquid separator 34, and the third term is the separated blowdown water flow rate Mb of the liquid discharge amount flowing out of the gas-liquid separator 34. Equation (7) is obtained by rearranging equation (6). The amount of steam input and output to the gas-liquid separator 34 is expressed as (Mp + Mc) × Q.

[0031] In step S7, the gas phase ratio Q is calculated based on equation (7). Equation (7) is obtained by rearranging equation (6). Thus, the gas phase ratio Q can be determined from the feed water flow rate Mp, the separated circulating water flow rate Mc, the liquid level change amount Ms in the gas-liquid separator 34, and the separated blowdown water flow rate Mb.

[0032] In step S8, the rotational speed N of the water supply pump 38 is instructed based on the gas phase ratio Q to control the water supply flow rate Mp.

[0033] Figure 3 is a flowchart showing the detailed control of the supply water flow rate Mp in step 8. In step S81, the gas phase ratio Q is compared with the first threshold. If Q ≥ the first threshold, the process proceeds to step S82 (YES), and if Q < the first threshold, the process proceeds to step S83 (NO). In step 72, the rotational speed N of the water supply pump 38 is increased. In step S83, the gas phase ratio Q is compared with the second threshold. If Q ≤ the second threshold, the process proceeds to step S84 (YES). In step S84, the rotational speed N of the water supply pump 38 is decreased. After steps S82 and S83, and in step 73, if Q > the second threshold, the process shown in Figure 3 is terminated. An appropriate limiter may be provided for the rotational speed N.

[0034] As mentioned above, if the gas phase ratio Q is 1.0, there is a concern that impurities will precipitate. Also, if the gas phase ratio Q is too low, the efficiency of steam generation will be poor. Therefore, there is an appropriate range for the gas phase ratio Q, and it is controlled to stay within this range, with the upper limit being the first threshold and the lower limit being the second threshold. The first and second thresholds may vary depending on system conditions, operating environment, etc., but for example, the first threshold is about 0.7 and the second threshold is about 0.5.

[0035] The control based on each threshold may have hysteresis characteristics to prevent chattering, etc. The control of increasing or decreasing the rotational speed N may be PID control or learning-based control based on deviations exceeding the first threshold and deviations below the second threshold. In addition, the first threshold is greater than or equal to the second threshold, but the first threshold may be equal to the second threshold. In this case, the predetermined range for the gas phase ratio Q is a constant value. The predetermined range is the target value, and it is permissible for the gas phase ratio Q to deviate slightly from the predetermined range during the control process.

[0036] To increase or decrease the supply water flow rate Mp, in addition to controlling the rotational speed N of the water supply pump 38, a flow control valve or the like may also be used. To control the gas phase ratio Q to be within an appropriate range, in addition to increasing or decreasing the supply water flow rate Mp, the rotational speed of the compressor 20 may be increased or decreased to adjust the refrigerant flow rate of the heat pump section 12. In other words, at least one of the supply water flow rate Mp and the refrigerant flow rate should be controlled so that the gas phase ratio Q is within a predetermined range.

[0037] Figure 4 is a schematic circuit diagram showing a part of the steam generation heat pump device 10 when performing calibration processing of the volumetric efficiency η. As described above, the supply water flow rate Mp is calculated by equation (1). However, the volumetric efficiency η in equation (1) may change due to deterioration of the water supply pump 38 such as wear. Therefore, it is desirable to detect the degree of deterioration of the water supply pump 38 and perform maintenance, inspection, or calibration of the flow rate calculation. In this embodiment, since a liquid level gauge is attached to the gas-liquid separator 34, when the water supply pump 38 is operated while the heat pump unit 12 is stopped, the supply water flow rate Mp of the water supply pump 38 can be determined from the change in liquid level height H ΔH. Therefore, by periodically supplying water under the same conditions and comparing the supply water flow rate Mp at that time, the volumetric efficiency η at that time can be determined.

[0038] One way to determine the volumetric efficiency η is, for example, to store the time T0 required to reach a specified change amount ΔH during the previous calibration, and if, as in the current case, the feedwater pump 38 is rotated at a predetermined rotational speed and it takes time T1 (≧T0) to reach the specified change amount ΔH, then the correction coefficient α is α = T0 / T1 (≦1.0), and η can be rewritten as η ← η × α. Alternatively, the change amount ΔH over a specified time during the previous calibration may be stored as H0, and the change amount ΔH when the feedwater pump 38 is rotated over a specified time may be taken as H1, and the correction coefficient α may be α = H1 / H0 (≦1.0). For a new feedwater pump 38, the volumetric efficiency η can be, for example, the value listed in the specifications. In Figure 4, the condenser 22 and the gas-liquid separator 34 are set at approximately the same height, but the position of the condenser 22 is not important as long as a sufficient gas phase range is secured in the gas-liquid separator 34 to measure the change amount ΔH.

[0039] By calibrating the volumetric efficiency η in this way, the calculation error of the supply water flow rate Mp is suppressed, and the lifespan of the water supply pump 38 can be substantially extended. However, if the required supply water flow rate Mp can no longer be obtained even at the maximum rotational speed of the water supply pump 38, it is desirable to replace it.

[0040] The present invention is not limited to the embodiments described above, and can be freely modified without departing from the spirit of the invention.

[0041] 10 Steam generating heat pump device 12 Heat pump unit 14 Steam generating unit 16 Control unit 18 Evaporator 20 Compressor 20a First compressor 20b Second compressor 22 Condenser 24 Subcooler 26 First expansion valve 28 Second expansion valve 30, 34 Gas-liquid separator 36 Heat recovery exchanger 38 Water supply pump 40 Control valve 70 Storage unit 72 Program

Claims

1. A steam generating heat pump device comprising: a control unit; a thermosiphon circuit including a condenser and a gas-liquid separator, wherein the separated circulating water of the liquid phase separated by the gas-liquid separator and the separated blowdown water to be blown down, the separated circulating water and the supply water supplied from the water supply pump, are combined at a confluence point, the combined water is boiled in the condenser and supplied to the gas-liquid separator; and a heat pump unit that evaporates and compresses a refrigerant with heat recovered from heat source water, and the refrigerant is used to boil the combined water in the condenser, wherein the control unit calculates the flow rate of the separated circulating water based on a weighted average formula from the temperature of the separated circulating water before the confluence point, the temperature of the supply water before the confluence point, the flow rate of the supply water before the confluence point, and the temperature of the combined water.

2. The steam generation heat pump apparatus according to claim 1, characterized in that the control unit calculates the gas phase ratio of the combined water boiled in the condenser from the supply water flow rate, the separated circulating water flow rate, the amount of change in the liquid level of the gas-liquid separator, and the separated blowdown water flow rate, and controls at least one of the supply water flow rate and the refrigerant flow rate of the refrigerant so that the gas phase ratio is within a predetermined range.

3. The steam generating heat pump device according to claim 2, comprising a heat recovery exchanger that exchanges heat between the supply water and the separated blowdown water, wherein the control unit calculates the flow rate of the separated blowdown water from the temperature difference of the supply water before and after the heat recovery exchanger, the temperature difference of the separated blowdown water before and after the heat recovery exchanger, and the flow rate of the supply water.

4. The steam generating heat pump device according to claim 1, characterized in that the control unit calculates the supply water flow rate from the rotational speed instructed to the water supply pump, the volume of the water supply pump, and the volumetric efficiency.

5. A control method for a steam generating heat pump device comprising: a control unit; a thermosiphon circuit including a condenser and a gas-liquid separator, wherein the separated circulating water of the liquid phase separated by the gas-liquid separator and the separated blowdown water to be blown down, the separated circulating water and the supply water supplied from the water supply pump, merge at a confluence point, the merged water is boiled in the condenser and supplied to the gas-liquid separator; and a heat pump unit that evaporates and compresses a refrigerant with heat recovered from heat source water, and uses the refrigerant to boil the merged water in the condenser, wherein the control unit reads or determines the temperature of the separated circulating water before the confluence point, the temperature of the supply water before the confluence point, the flow rate of the supply water before the confluence point, and the temperature of the merged water from sensors, and calculates the flow rate of the separated circulating water based on a weighted average formula from the temperature of the separated circulating water, the temperature of the supply water, the flow rate of the supply water, and the temperature of the merged water. A control method for a steam generation heat pump device, characterized by calculating the gas phase ratio of the combined water boiled in the condenser from the supply water flow rate, the separated circulating water flow rate, the amount of liquid level change in the gas-liquid separator, and the separated blowdown water flow rate, and controlling at least one of the supply water flow rate and the refrigerant flow rate of the refrigerant so that the gas phase ratio is within a predetermined range.

6. A steam generating heat pump device comprising: a control unit including a memory unit; a thermosiphon circuit including a condenser and a gas-liquid separator, wherein the separated circulating water of the liquid phase separated by the gas-liquid separator and the separated blowdown water to be blown down, the separated circulating water and the supply water supplied from the water supply pump, merge at a confluence point, the merged water is boiled in the condenser and supplied to the gas-liquid separator; and a heat pump unit that evaporates and compresses a refrigerant with heat recovered from a heat source water, and uses the refrigerant to boil the merged water in the condenser, wherein the control unit reads from the memory unit and executes a program for calculating the flow rate of the separated circulating water, comprising the steps of reading or determining the temperature of the separated circulating water before the confluence point, the temperature of the supply water before the confluence point, the flow rate of the supply water before the confluence point, and the temperature of the merged water from sensors; A program for calculating the flow rate of separated circulating water, characterized by causing the control unit to perform the steps of calculating the flow rate of separated circulating water based on a weighted average formula from the temperature of the separated circulating water, the temperature of the supply water, the flow rate of the supply water, and the temperature of the combined water.

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