Heat pump steam heating device and control method

Abstract

The present invention relates to a heat pump steam heating device and a control method thereof. The heating device comprises a heat pump system and a steam system. The heat pump system comprises a heat pump compressor, a heat pump condenser and a heat pump evaporator connected in sequence. The heat pump evaporator is connected to the heat pump compressor. The steam system comprises a gas-liquid separator, a steam compressor and a heat-using mechanism connected in sequence. The inlet end of the gas-liquid separator is connected to the liquid outlet of the heat pump condenser. The heat pump compressor is connected to a first frequency converter, and the steam compressor is connected to a second frequency converter. When the heat load of the heat-using mechanism changes, the steam compressor and the heat pump compressor are coupled and frequency-converted, so that the heat of the water vapor entering the heat-using mechanism and the heat load of the heat-using mechanism are balanced. Compared with the prior art, the present invention controls the frequency coupling of the compressor so that the two operate in coordination, and the balance between the heat supply of the heat-using mechanism and the required heat load is achieved as quickly as possible, the temperature change fluctuation is reduced, and the high energy efficiency ratio operation of the device is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of steam heat pumps, and in particular to a heat pump steam heating device and a control method thereof. Background Art

[0002] As a good carrier of thermal energy, water vapor is widely used as a source of thermal energy and heating materials for manufacturing companies. Current water vapor generation technologies mostly use coal-fired, gas-fired or electric heating boilers. Traditional boiler heating methods are affected by fuel combustion and heat transfer processes, and the overall heating efficiency is low. At the same time, the large-scale use of primary energy has caused an increase in carbon emissions and environmental problems. With the popularization of heat pump devices and the gradual improvement of people's awareness of energy conservation, people have gradually applied heat pumps to steam heating devices in the process of technological development, thus obtaining heat pump steam heating devices, which can greatly reduce energy consumption in use. At the same time, as a normal pressure device, the heat pump is safe and reliable to use, and does not produce waste gas or tail gas, with good environmental benefits.

[0003] However, the existing heat pump steam heating device is only simply coupled in structure, and it is still easy to cause a lot of energy loss in the process of heat pump heating water. At the same time, in the heat pump heating process, when the heat load required by the user is the same as the heating amount provided by the heat pump system, the heat pump system has the best energy-saving effect, while the existing heat pump steam heating device is basically two independent systems, and the labor-consuming components between the two do not cooperate with each other. When the working conditions change, the entire heating device cannot be adjusted in time, which not only leads to large temperature fluctuations, but also leads to low operating efficiency of the entire device. Therefore, the existing heat pump steam technology needs to be improved and developed. Summary of the invention

[0004] The purpose of the present invention is to provide a heat pump steam heating device and a control method to overcome the defects of the above-mentioned prior art, realize the coordination and linkage between the heat pump system and the steam system, and improve the operating energy efficiency ratio of the entire heat pump steam heating device. In addition, the present invention also improves the structure of the heat pump steam heating device to improve the utilization rate of heat energy during operation.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A heat pump steam heating device, comprising a heat pump system and a steam system, wherein the heat pump system comprises a heat pump compressor, a heat pump condenser and a heat pump evaporator connected in sequence, the heat pump evaporator is connected to the heat pump compressor, the steam system comprises a gas-liquid separator, a steam compressor and a heat using mechanism connected in sequence, the inlet end of the gas-liquid separator is connected to the liquid outlet of the heat pump condenser;

[0007] The heat pump compressor is connected to a first frequency converter, and the steam compressor is connected to a second frequency converter; when the heat load of the heat-using mechanism changes, the steam compressor and the heat pump compressor are coupled and frequency-converted to balance the heat of the water vapor entering the heat-using mechanism and the heat load of the heat-using mechanism.

[0008] In another preferred embodiment, the liquid outlet of the gas-liquid separator is connected to a first water pump, and the liquid outlet of the gas-liquid separator is connected to the liquid inlet of the heat pump condenser through the first water pump.

[0009] In another preferred example, the heat pump compressor is a positive displacement compressor using lubricating oil, which is connected to a lubricating oil cooler, the liquid outlet of the heat-using mechanism is connected to a second water pump, the second water pump is connected to the cooling inlet of the lubricating oil cooler, and the cooling outlet of the lubricating oil cooler is connected to the liquid inlet of the heat pump condenser.

[0010] In another preferred embodiment, the heat pump evaporator adopts an air-cooled fin-tube heat exchanger or a shell-and-tube heat exchanger.

[0011] In another preferred embodiment, a throttling mechanism is provided between the heat pump condenser and the heat pump evaporator.

[0012] In another preferred embodiment, the steam compressor is an oil-free screw steam compressor.

[0013] A control method for a heat pump steam heating device is applied to any of the heat pump steam heating devices described above. When the user's heat load changes, the control method performs the following steps:

[0014] Obtain the pressure signal P2 at the outlet of the steam compressor, and determine whether the pressure signal P2 is within the set first interval: if within the first interval, maintain the current frequencies of the steam compressor and the heat pump compressor; if greater than the first interval, enter the first subroutine; if less than the first interval, enter the second subroutine; the first interval is [a*P2s, b*P2s], where a and b are set coefficients, and P2s is a set standard value;

[0015] First subroutine:

[0016] Step S11, reduce the frequency of the steam compressor according to the set step length, wait for the set first interval time, then obtain the pressure signal P1 of the gas-liquid separator, and determine whether the pressure signal P1 is greater than the set first threshold:

[0017] If yes, the frequency of the heat pump compressor is reduced according to the set step length, and the set first interval time is also waited. After the first interval time is reached, step S12 is executed;

[0018] If not, the current frequency of the heat pump compressor is maintained and step S12 is executed;

[0019] Step S12, obtaining the pressure signal P2 at the outlet of the steam compressor again, and determining whether the pressure signal P2 is greater than the first interval:

[0020] If yes, restart the first subroutine;

[0021] If not, maintain the current frequency of the steam compressor and then execute step S13;

[0022] Step S13, obtaining the pressure signal P1 of the gas-liquid separator again, and determining whether the pressure signal P1 is greater than the set first threshold:

[0023] If yes, continue to reduce the frequency of the heat pump compressor according to the set step length, wait for the set first interval time, and re-execute step S13 after reaching the first interval time;

[0024] If not, maintain the current frequency of the heat pump compressor;

[0025] The first threshold is c*P1s, where c is a set coefficient and P1s is a set standard value;

[0026] Second subroutine:

[0027] Step S21, increase the frequency of the steam compressor according to the set step length, wait for the set first interval time, then obtain the pressure signal P1 of the gas-liquid separator, and determine whether the pressure signal P1 is less than the set second threshold:

[0028] If yes, the frequency of the heat pump compressor is increased according to the set step length, and the set first interval time is also waited. After the first interval time is reached, step S22 is executed;

[0029] If not, the current frequency of the heat pump compressor is maintained and step S22 is executed;

[0030] Step S22, obtaining the pressure signal P2 at the outlet of the steam compressor again, and determining whether the pressure signal P2 is less than the first interval:

[0031] If yes, restart the second subroutine;

[0032] If not, maintain the current frequency of the steam compressor and then execute step S23;

[0033] Step S23, obtaining the pressure signal P1 of the gas-liquid separator again, and determining whether the pressure signal P1 is less than the set second threshold:

[0034] If yes, continue to increase the frequency of the heat pump compressor according to the set step length, wait for the set first interval time, and re-execute step S23 after reaching the first interval time;

[0035] If not, maintain the current frequency of the heat pump compressor;

[0036] The second threshold is d*P1s, where d is a set coefficient and P1s is a set standard value;

[0037] When the frequencies of the steam compressor and the heat pump compressor remain unchanged for more than the set second interval time, the current pressure signal P2 and the pressure signal P1 are respectively used as the standard value P2s and the standard value P1s.

[0038] In another preferred embodiment, when the ambient temperature of the heat pump steam heating device decreases, the frequency of the heat pump compressor is directly increased according to the set step length until the pressure signal P1 of the gas-liquid separator returns to the standard value P1s.

[0039] In another preferred embodiment, the setting range of coefficient a is 0.9 to 0.98, and the setting range of coefficient b is 1.02 to 1.1.

[0040] In another preferred embodiment, the setting range of the coefficient c is 1.05 to 1.15, and the setting range of the coefficient d is 0.85 to 0.95.

[0041] In another preferred embodiment, the steam compressor and the heat pump compressor are adjusted at a set step frequency of at least 1 Hz.

[0042] In another preferred embodiment, the initial values ​​of the standard value P2s and the standard value P1s are set in advance in the control system based on the control logic according to user requirements. After the system is turned on, the steam compressor and the heat pump compressor will also run directly at the initial set frequency, that is, the initial speed.

[0043] In another preferred embodiment, the first interval time is 60 seconds, and the second interval time is 30 seconds.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1) The present invention respectively sets a first frequency converter and a second frequency converter on the heat pump compressor and the steam compressor, and controls the frequency coupling of the compressor so that the two can work in coordination, so as to achieve the balance between the heat supply of the heat-using mechanism and the required heat load as quickly as possible, reduce the temperature fluctuation, and realize the high energy efficiency ratio operation of the device.

[0046] 2) The heat pump compressor of the present invention adopts a positive displacement compressor using lubricating oil, and sends the cooling water discharged from the heat mechanism to the lubricating oil cooler. Not only can the cooling water be used to ensure the sustainable and normal operation of the heat pump compressor, but also the working heat of the lubricating oil is fully utilized, thereby improving the energy utilization rate of the heat pump condenser.

[0047] 3) The present invention controls the frequency of the compressor by collecting the pressure signal P2 at the outlet of the steam compressor and the pressure signal P1 of the gas-liquid separator. The monitored data is accurate and highly sensitive, which can improve the sensitivity of the control feedback and achieve rapid temperature adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a structural schematic diagram of the present invention.

[0049] Figure 2 It is the overall flow chart of the control method of the present invention.

[0050] Figure 3 This is a flow chart of the first subroutine of the control method of the present invention.

[0051] Figure 4 This is a flow chart of the second subroutine of the control method of the present invention.

[0052] Figure numerals: 1-heat pump compressor; 2-heat pump condenser; 3-throttling mechanism; 4-heat pump evaporator; 5-gas-liquid separator; 6-steam compressor; 7-heat using mechanism; 8-first water pump; 9-second water pump; 10-first inverter; 11-second inverter; 12-first pressure sensor; 13-second pressure sensor; 14-lubricating oil cooler; 15-coolant pipeline; 16-steam pipeline; 17-hot water pipeline. DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0054] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0055] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a heat pump steam heating device, including a heat pump system and a steam system. The heat pump system includes a heat pump compressor 1, a heat pump condenser 2, a throttling mechanism 3 and a heat pump evaporator 4. The steam system includes a gas-liquid separator 5, a steam compressor 6 and a heat using mechanism 7.

[0059] In the heat pump system, the heat pump compressor 1, the heat pump condenser 2, the throttling mechanism 3 and the heat pump evaporator 4 are connected in sequence through the coolant pipe 15, and the heat pump evaporator 4 is connected to the heat pump compressor 1 to form a cycle. R245fa is used as the refrigerant in the coolant pipe 15. The heat pump compressor 1 adopts a positive displacement compressor using lubricating oil, and is connected to a lubricating oil cooler 14. The heat pump evaporator 4 adopts an air-cooled fin-tube heat exchanger or a shell-and-tube heat exchanger. In this embodiment, an air-cooled fin-tube heat exchanger is preferably used. The throttling mechanism 3 adopts a conventional structure without limitation, such as a one-way valve with adjustable opening, which is used to control the flow rate of the refrigerant.

[0060] In the steam system, the gas outlet of the gas-liquid separator 5, the steam compressor 6 and the inlet of the heat-using mechanism 7 are connected in sequence through the steam pipe 16. The inlet end of the gas-liquid separator 5 is connected to the liquid outlet of the heat pump condenser 2. The steam compressor 6 specifically adopts an oil-free screw water vapor compressor. In this embodiment, the liquid outlet of the gas-liquid separator 5 is also connected to the first water pump 8, and the liquid outlet of the gas-liquid separator 5 is connected to the liquid inlet of the heat pump condenser 2 through the first water pump 8, and the connection adopts a hot water pipe 17. This structure allows the hot water separated by the gas-liquid separator 5 to enter the steam condenser again, and the waste heat of the hot water is reused. In this embodiment, the heat-using mechanism 7 is the user's end, and the heat-using mechanism 7 can adopt a conventional heat exchanger. After the heat-using mechanism 7 releases heat, the water vapor forms condensed water and flows out. The liquid outlet of the heat-using mechanism 7 is connected to the second water pump 9, and the second water pump 9 is connected to the cooling inlet of the lubricating oil cooler 14, and the cooling outlet of the lubricating oil cooler is connected to the liquid inlet of the heat pump condenser 2. This structure sends the cooling water discharged from the heat-using mechanism 7 to the lubricating oil cooler 14, which can not only use the cooling water to ensure the sustainable normal operation of the heat pump compressor 1, thereby reducing the exhaust temperature of the heat pump compressor 1, but also make full use of the working heat of the lubricating oil, thereby improving the energy utilization rate of the heat pump condenser 2. In this embodiment, the water temperature at the outlet of the heat pump condenser 2 can reach 105°C; after the high-temperature hot water enters the gas-liquid separator 5, the water vapor generated by flash evaporation enters the steam compressor 6 and is compressed, and after the pressure is increased to more than 150°C, it is sent to the heat-using mechanism 7 for use.

[0061] The heat pump steam heating device also includes a control system, including a master controller, a first frequency converter 10, a second frequency converter 11, a first pressure sensor 12 and a second pressure sensor 13. The first frequency converter 10 is connected to the heat pump compressor 1 for frequency regulation of the heat pump compressor 1; the second frequency converter 11 is connected to the steam compressor 6 for frequency regulation of the steam compressor 6; the first pressure sensor 12 is arranged in the gas-liquid separator 5, and the second pressure sensor 13 is arranged at the outlet of the steam compressor 6. When the heat load of the heat-using mechanism 7 changes, the values ​​of the first pressure sensor 12 and the second pressure sensor 13 change, and the master controller couples and converts the steam compressor 6 and the heat pump compressor 1 through the first frequency converter 10 and the second frequency converter 11, so that the heat of the water vapor entering the heat-using mechanism 7 and the heat load of the heat-using mechanism 7 are balanced, thereby reducing the temperature change fluctuation and achieving high energy efficiency ratio operation.

[0062] The basic principle of this embodiment is: the heat pump system raises the temperature of low-temperature water and enters the gas-liquid separator 5, where the liquid water and water vapor are separated. Then the water vapor in the gas-liquid separator 5 enters the steam compressor 6 for compression and is then provided to the user; the condensed water in the gas-liquid separator 5 enters the heat pump condenser 2 for recycling. After the user uses the completed water vapor to condense into liquid water, it is transported to the heat pump condenser 2 of the heat pump system by the second water pump 9. When the user's heat demand changes, by adjusting the speed of the heat pump compressor 1 and the steam compressor 6, the heat pump system and the steam system are intelligently coupled and controlled to provide the user with the required heating amount of water vapor.

[0063] In summary, this embodiment has the following specific features:

[0064] The heat pump system heats the liquid water in the heat pump condenser 2 by utilizing the heat in the atmosphere or the heat in the wastewater and circulating the refrigerant R245fa. In order to reduce the exhaust temperature of the heat pump compressor 1 and ensure the safety of the heat pump system, the heat pump compressor 1 is provided with an external lubricating oil cooler, which uses the condensed water generated from the user side to cool the lubricating oil of the heat pump compressor 1 and reduce the lubricating oil temperature of the heat pump compressor 1. At the same time, the temperature of the liquid condensed water is further increased and enters the heat pump condenser 2 of the heat pump system.

[0065] The high-temperature hot water of the heat pump system is not hot enough to meet the user's demand for heat source. At this time, the steam compressor 6 is used to increase the pressure and temperature of the water vapor to meet the thermal parameters required by the user and then supply it to the user. The steam compressor 6 is an oil-free twin-screw compressor, and its frequency (speed) is controlled by the second inverter 11. After the high-temperature water vapor releases heat energy on the user side, it changes from gas to liquid, and is then transported by the water pump to the heat pump condenser 2 of the heat pump system.

[0066] Example 2

[0067] This embodiment provides a control method for the heat pump steam heating device as described in Embodiment 1, and the principle is as follows:

[0068] The pressure signal P2 at the outlet of the steam compressor 6 and the pressure signal P1 of the gas-liquid separator 5 are acquired in real time.

[0069] During normal operation, the inlet pressure and the user-side pressure of the steam compressor 6 remain constant, and the pressure signals are respectively preset standard values ​​P1s and P2s.

[0070] When the heat load required by the user decreases, the heat supply of the heat pump system is fixed, and the pressure signal P2 measured at this time increases. At this time, the control signal controls the inverter of the steam compressor 6 to reduce the speed of the steam compressor 6; then, the pressure value of the pressure signal P1 increases, and the control signal controls the inverter of the heat pump compressor 1 to reduce the speed of the heat pump compressor 1. This adjustment method is carried out in steps, gradually reducing the pressure of the pressure signal P2 until it matches the user side.

[0071] When the heat load required by the user increases, the heat supply of the heat pump system is fixed, and the pressure value of the pressure signal P2 decreases. At this time, the control signal controls the inverter of the steam compressor 6 to increase the speed of the steam compressor 6; then, the pressure value of the pressure signal P1 decreases, and the control signal controls the inverter of the heat pump compressor 1 to increase the speed of the heat pump compressor 1. This adjustment method is carried out in steps, gradually increasing the pressure value of the pressure signal P2 until it matches the user side.

[0072] When the ambient temperature changes and causes the heating capacity of the heat pump system to decrease, the pressure signal P1 decreases. At this time, the speed of the heat pump compressor 1 is directly increased to increase the pressure signal P1 to the original pressure P1s.

[0073] The initial values ​​of the standard value P2s and the standard value P1s are set in advance in the control system based on the control logic according to user needs. After the system is turned on, the steam compressor 6 and the heat pump compressor 1 will also run directly at the initial set frequency, that is, the initial speed.

[0074] The specific steps of the control method of this embodiment are as follows:

[0075] 1. When the user's heat load changes, the control method executes the general process, such as Figure 2 As shown:

[0076] Obtain the pressure signal P2 at the outlet of the steam compressor 6, and determine whether the pressure signal P2 is within the set first interval: if it is within the first interval, maintain the current frequencies of the steam compressor 6 and the heat pump compressor 1; if it is greater than the first interval, enter the first subroutine; if it is less than the first interval, enter the second subroutine.

[0077] In the overall process, the first interval is set as [a*P2s, b*P2s], where a and b are set coefficients, and P2s is a set standard value. In this embodiment, the first interval is specifically [0.95*P2s, 1.05*P2s].

[0078] The first subroutine is Figure 3 As shown:

[0079] Step S11, reduce the frequency of the steam compressor 6 according to the set step length, wait for the set first interval time, then obtain the pressure signal P1 of the gas-liquid separator 5, and determine whether the pressure signal P1 is greater than the set first threshold:

[0080] If yes, the frequency of the heat pump compressor 1 is reduced according to the set step length, and the set first interval time is also waited. After the first interval time is reached, step S12 is executed;

[0081] If not, the current frequency of the heat pump compressor 1 is maintained and step S12 is executed.

[0082] Step S12, obtaining the pressure signal P2 at the outlet of the steam compressor 6 again, and determining whether the pressure signal P2 is greater than the first interval:

[0083] If yes, restart the first subroutine;

[0084] If not, the current frequency of the steam compressor 6 is maintained, and then step S13 is executed.

[0085] Step S13, obtaining the pressure signal P1 of the gas-liquid separator 5 again, and determining whether the pressure signal P1 is greater than the set first threshold:

[0086] If yes, continue to reduce the frequency of the heat pump compressor 1 according to the set step length, wait for the set first interval time, and re-execute step S13 after reaching the first interval time;

[0087] If not, maintain the current heat pump compressor frequency.

[0088] In the first subroutine, the first threshold is c*P1s, where c is a set coefficient. In this embodiment, the first threshold is specifically 1.1*P1s. The first time interval is one minute.

[0089] The second subroutine is Figure 4 As shown:

[0090] Step S21, increase the frequency of the steam compressor 6 according to the set step length, wait for the set first interval time, then obtain the pressure signal P1 of the gas-liquid separator 5, and determine whether the pressure signal P1 is less than the set second threshold:

[0091] If yes, the frequency of the heat pump compressor 1 is increased according to the set step length, and the set first interval time is also waited. After the first interval time is reached, step S22 is executed;

[0092] If not, the current frequency of the heat pump compressor 1 is maintained and step S22 is executed.

[0093] Step S22, obtaining the pressure signal P2 at the outlet of the steam compressor 6 again, and determining whether the pressure signal P2 is less than the first interval:

[0094] If yes, restart the second subroutine;

[0095] If not, the current frequency of the steam compressor 6 is maintained, and then step S23 is executed.

[0096] Step S23, obtaining the pressure signal P1 of the gas-liquid separator 5 again, and determining whether the pressure signal P1 is less than the set second threshold value:

[0097] If yes, continue to increase the frequency of the heat pump compressor 1 according to the set step length, wait for the set first interval time, and re-execute step S23 after reaching the first interval time;

[0098] If not, maintain the current heat pump compressor frequency.

[0099] In the second subroutine, the second threshold is d*P1s, where d is a set coefficient. In this embodiment, the second threshold is specifically 0.9*P1s. The first time interval is one minute, the same as step 2.

[0100] When the frequencies of the steam compressor 6 and the heat pump compressor 1 remain unchanged for more than the set second interval time, the current pressure signal P2 and pressure signal P1 are used as the standard value P2s and the standard value P1s respectively. The second interval time is at least 30 seconds, and 30 seconds is preferably used in this embodiment. In all the above steps, the set step frequency for the steam compressor 6 and the heat pump compressor 1 to be adjusted is generally 1Hz, which can ensure that both compressors can be at the operating speed of the system's overall optimal COP (heating capacity per unit power).

[0101] 2. When the ambient temperature of the heat pump steam heating device decreases, the frequency of the heat pump compressor 1 is directly increased according to the set step length until the pressure signal P1 of the gas-liquid separator 5 returns to the standard value P1s.

[0102] The above control method synergistically controls the coupled operation of the heat pump system and the steam system, adjusts the heating amount of the entire heating device in real time, and achieves high energy efficiency ratio operation.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for a heat pump steam heating device, characterized in that: Applicable to a heat pump steam heating device, the heat pump steam heating device comprising a heat pump system and a steam system, the heat pump system comprising a heat pump compressor (1), a heat pump condenser (2) and a heat pump evaporator (4) connected in sequence, the heat pump evaporator (4) being connected to the heat pump compressor (1), the steam system comprising a gas-liquid separator (5), a steam compressor (6) and a heat using mechanism (7) being connected in sequence, the inlet end of the gas-liquid separator (5) being connected to the liquid outlet of the heat pump condenser (2); The heat pump compressor (1) is connected to a first frequency converter (10), and the steam compressor (6) is connected to a second frequency converter (11); when the heat load of the heat-using mechanism (7) changes, the steam compressor (6) and the heat pump compressor (1) are coupled and frequency-converted, so that the heat of the water vapor entering the heat-using mechanism (7) and the heat load of the heat-using mechanism (7) are balanced; When the user's heat load changes, the control method performs the following steps: Obtaining a pressure signal P2 at the outlet of the steam compressor (6), and determining whether the pressure signal P2 is within a set first interval: if within the first interval, maintaining the current frequencies of the steam compressor (6) and the heat pump compressor (1); if greater than the first interval, entering a first subroutine; if less than the first interval, entering a second subroutine; the first interval is [a*P2s, b*P2s], where a and b are set coefficients, and P2s is a set standard value; First subroutine: Step S11, reducing the frequency of the steam compressor (6) according to a set step length, waiting for a set first interval time, and then obtaining a pressure signal P1 of the gas-liquid separator (5), and determining whether the pressure signal P1 is greater than a set first threshold value: If yes, the frequency of the heat pump compressor (1) is reduced according to the set step length, and the set first interval time is also waited. After the first interval time is reached, step S12 is executed; If not, the current frequency of the heat pump compressor (1) is maintained and step S12 is executed; Step S12, obtaining the pressure signal P2 at the outlet of the steam compressor (6) again, and determining whether the pressure signal P2 is greater than the first interval: If yes, restart the first subroutine; If not, maintain the current frequency of the steam compressor (6), and then execute step S13; Step S13, obtaining the pressure signal P1 of the gas-liquid separator (5) again, and determining whether the pressure signal P1 is greater than a set first threshold: If yes, continue to reduce the frequency of the heat pump compressor (1) according to the set step length, wait for the set first interval time, and after the first interval time is reached, re-execute step S13; If not, maintain the current frequency of the heat pump compressor; The first threshold is c* P1s, where c is a set coefficient and P1s is a set standard value; Second subroutine: Step S21, increasing the frequency of the steam compressor (6) according to a set step length, waiting for a set first interval time, and then obtaining the pressure signal P1 of the gas-liquid separator (5), and determining whether the pressure signal P1 is less than a set second threshold value: If yes, the frequency of the heat pump compressor (1) is increased according to the set step length, and the set first interval time is also waited. After the first interval time is reached, step S22 is executed; If not, the current frequency of the heat pump compressor (1) is maintained and step S22 is executed; Step S22, obtaining the pressure signal P2 at the outlet of the steam compressor (6) again, and determining whether the pressure signal P2 is less than the first interval: If yes, restart the second subroutine; If not, maintain the current frequency of the steam compressor (6), and then execute step S23; Step S23, obtaining the pressure signal P1 of the gas-liquid separator (5) again, and determining whether the pressure signal P1 is less than a set second threshold value: If yes, continue to increase the frequency of the heat pump compressor (1) according to the set step length, wait for the set first interval time, and after reaching the first interval time, re-execute step S23; If not, maintain the current frequency of the heat pump compressor; The second threshold is d*P1s, where d is a set coefficient and P1s is a set standard value; When the frequencies of the steam compressor (6) and the heat pump compressor (1) remain unchanged for more than a set second interval time, the current pressure signal P2 and the pressure signal P1 are used as the standard value P2s and the standard value P1s respectively; Among them, the setting range of coefficient a is 0.9~0.98, the setting range of coefficient b is 1.02~1.1, the setting range of coefficient c is 1.05~1.15, and the setting range of coefficient d is 0.85~0.

95.

2. A control method for a heat pump steam heating device according to claim 1, characterized in that: When the ambient temperature of the heat pump steam heating device decreases, the frequency of the heat pump compressor (1) is directly increased according to the set step length until the pressure signal P1 of the gas-liquid separator (5) returns to the standard value P1s.

3. The control method of a heat pump steam heating device according to claim 1, characterized in that: The steam compressor (6) and the heat pump compressor (1) are adjusted with a set step frequency of at least 1 Hz.

4. The control method of a heat pump steam heating device according to claim 1, characterized in that: The liquid outlet of the gas-liquid separator (5) is connected to a first water pump (8), and the liquid outlet of the gas-liquid separator (5) is connected to the liquid inlet of the heat pump condenser (2) through the first water pump (8).

5. The control method of a heat pump steam heating device according to claim 1, characterized in that: The heat pump compressor (1) is a positive displacement compressor using lubricating oil and is connected to a lubricating oil cooler (14). The liquid outlet of the heat-using mechanism (7) is connected to a second water pump (9). The second water pump (9) is connected to a cooling inlet of the lubricating oil cooler (14). The cooling outlet of the lubricating oil cooler (14) is connected to a liquid inlet of a heat pump condenser (2).

6. The control method of a heat pump steam heating device according to claim 1, characterized in that: The heat pump evaporator (4) adopts an air-cooled fin-tube heat exchanger or a shell-and-tube heat exchanger.

7. The control method of a heat pump steam heating device according to claim 1, characterized in that: A throttling mechanism (3) is provided between the heat pump condenser (2) and the heat pump evaporator (4).

8. The control method of a heat pump steam heating device according to claim 1, characterized in that: The steam compressor (6) is an oil-free screw water vapor compressor.

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