Cascade steam heat pump unit

Abstract

The utility model discloses a cascade type steam heat pump unit which comprises a first compressor, a second compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first expansion valve, a second expansion valve, a first water pump, a second water pump, a third water pump, a flash tank and a first water tank. According to the cascade type high-temperature steam heat pump unit, different modes can be switched through the specific connection relation of all the components, the functions of heat storage at night and steam preparation in the daytime can be achieved, the advantage of valley electricity is fully played, the cascade type high-temperature steam heat pump unit is more energy-saving, and the operation cost is further reduced; in addition, the unit can obtain heat from chilled water to prepare steam, the purpose of combined supply of cold and heat is achieved, and the comprehensive energy efficiency of the system is further improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of heat pump technical field, specifically relates to a kind of cascade steam heat pump unit. BACKGROUND

[0002] Steam heat pump unit is a new type of compression high-temperature heat pump device for the purpose of generating high-temperature steam, as a clean energy industrial heat system, its main components are heat pump steam unit, flash tank and steam compressor, high-temperature heat pump unit generates 80~90℃ high-temperature hot water into flash tank to produce low-temperature low-pressure steam, usually the steam at this temperature and pressure cannot meet the industrial heat demand, therefore the steam produced by flash tank needs to be compressed by steam compressor to increase the pressure and temperature, so that it can be used at the end. At the same time, as the water in the flash tank is constantly converted into steam, the liquid level in the tank continues to drop, the conventional system uses the method of directly supplementing tap water into the flash tank, the temperature of tap water is low, and directly supplementing low-temperature water can easily cause the temperature inside the flash tank to drop, which can cause the water to be unable to boil, resulting in the steam production process being unable to continue, the steam flow being unstable, and the steam temperature being too low; at the same time, the heat pump system needs to reach a higher condensing temperature to meet the heat source temperature to make the water boil, so the heat pump unit is in a relatively harsh operating condition, which can easily cause damage to the compressor and system components. In addition, relatively speaking, the electricity consumption during the day is more than at night, and the price is relatively higher, therefore, how to supply high-temperature steam at a relatively low cost is a problem to be solved in the field. SUMMARY

[0003] The utility model aims at overcoming the defects of prior art, and provides an improved cascade steam heat pump unit, which can at least solve one problem existing in the prior art.

[0004] To achieve the above-mentioned purpose, the utility model adopts the technical scheme of:

[0005] A cascade steam heat pump unit, which comprises a first compressor, a second compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first expansion valve, a second expansion valve, a first water pump, a second water pump, a third water pump, a flash tank and a first water tank.

[0006] The outlet of the first compressor, one refrigerant passage of the first heat exchanger, the first expansion valve, the second heat exchanger and the inlet of the first compressor are sequentially connected and constitute a first refrigerant circulation loop.

[0007] The outlet of the second compressor, one refrigerant passage of the third heat exchanger, the second expansion valve, one refrigerant passage of the fourth heat exchanger and the inlet of the second compressor are sequentially connected and constitute a second refrigerant circulation loop.

[0008] The inlet of the first water pump is communicated with the flash tank, and the outlet of the first water pump is respectively communicated with another refrigerant passage of the third heat exchanger and another refrigerant passage of the first heat exchanger; wherein the another refrigerant passage of the third heat exchanger is also communicated with the flash tank, and the another refrigerant passage of the first heat exchanger is also respectively communicated with the flash tank and the first water tank;

[0009] The another refrigerant passage of the fourth heat exchanger is arranged in parallel with the one refrigerant passage of the first heat exchanger;

[0010] The two ends of the second water pump are respectively communicated with the first water tank and the another refrigerant passage of the first heat exchanger;

[0011] The two ends of the third water pump are respectively communicated with the first water tank and the flash tank.

[0012] According to the utility model, the cascade steam heat pump unit includes hot water mode, steam mode, water supplement steam mode, first water tank constant temperature mode and first water tank constant temperature steam mode;

[0013] When the cascade steam heat pump unit is in the hot water mode, the first compressor is in the working state, the second compressor is in the non-working state, the first water pump and the second water pump are respectively in the open state, and the third water pump is in the closed state;

[0014] When the cascade steam heat pump unit is in the steam mode, the first compressor and the second compressor are both in the working state, the first water pump is in the open state, and the second water pump and the third water pump are respectively in the closed state;

[0015] When the cascade steam heat pump unit is in the water supplement steam mode, the first compressor and the second compressor are both in the working state, the first water pump and the third water pump are respectively in the open state, and the second water pump is in the closed state;

[0016] When the cascade steam heat pump unit is in the first water tank constant temperature mode, the first compressor is in the working state, the second compressor is in the non-working state, the first water pump and the third water pump are respectively in the closed state, and the second water pump is in the open state;

[0017] When the cascade steam heat pump unit is in the first water tank constant temperature steam mode, the first compressor and the second compressor are both in the working state, and the first water pump and the second water pump are respectively in the open state.

[0018] According to some preferred aspects of the utility model, the cascade steam heat pump unit further includes a first valve, a second valve, a third valve, a fourth valve, a fifth valve and a sixth valve;

[0019] The two ends of the first valve are respectively communicated with the outlet of the first compressor and the one refrigerant passage of the first heat exchanger;

[0020] The two ends of the second valve are respectively communicated with the outlet of the first compressor and the other refrigerant passage of the fourth heat exchanger;

[0021] The two ends of the third valve are respectively communicated with the outlet of the first water pump and the other refrigerant passage of the first heat exchanger;

[0022] The two ends of the fourth valve are respectively communicated with the outlet of the first water pump and the other refrigerant passage of the third heat exchanger;

[0023] The two ends of the fifth valve are respectively communicated with the other refrigerant passage of the first heat exchanger and the flash tank;

[0024] The two ends of the sixth valve are respectively communicated with the other refrigerant passage of the first heat exchanger and the first water tank.

[0025] In some embodiments of the utility model, when the cascade steam heat pump unit is in the hot water mode, the first valve, the third valve, the fifth valve and the sixth valve are all in the open state, and the second valve and the fourth valve are both in the closed state;

[0026] When the cascade steam heat pump unit is in the steam mode or the water replenishing steam mode, the first valve, the third valve, the fifth valve and the sixth valve are all in the closed state, and the second valve and the fourth valve are both in the open state;

[0027] When the cascade steam heat pump unit is in the first water tank constant temperature mode, the first valve and the sixth valve are both in the open state, and the second valve, the third valve, the fourth valve and the fifth valve are all in the closed state;

[0028] When the cascade steam heat pump unit is in the first water tank constant temperature steam mode, the first valve, the second valve, the fourth valve and the sixth valve are all in the open state, and the third valve and the fifth valve are both in the closed state.

[0029] In some embodiments of the utility model, the first valve and the second valve are respectively electrically controlled valves, and the third valve, the fourth valve, the fifth valve and the sixth valve are respectively electromagnetic valves.

[0030] In some embodiments of the utility model, the cascade steam heat pump unit further includes a steam output pipe communicated with the flash tank, and a pressure reducing valve arranged on the steam output pipe; when the cascade steam heat pump unit is in the hot water mode, the first water tank constant temperature mode, the pressure reducing valve is in a closed state; when the cascade steam heat pump unit is in the steam mode, the water replenishing steam mode, the first water tank constant temperature steam mode, the pressure reducing valve is in an open state.

[0031] In some embodiments of the utility model, the second compressor further includes a gas supplement port; the cascade steam heat pump unit further includes an economizer and a third expansion valve, one refrigerant passage of the economizer is connected in series between the one refrigerant passage of the third heat exchanger and the second expansion valve, another refrigerant passage of the economizer is communicated with the gas supplement port of the second compressor and the outlet of the third expansion valve respectively, and the inlet of the third expansion valve is communicated with the one refrigerant passage of the economizer.

[0032] In some embodiments of the utility model, the cascade steam heat pump unit further includes a second water tank, a fourth water pump, a seventh valve and an eighth valve, the second water tank, the fourth water pump, the seventh valve and the flash tank are communicated in sequence, and the second water tank, the fourth water pump, the eighth valve and the first water tank are communicated in sequence.

[0033] In some embodiments of the utility model, the cascade steam heat pump unit further includes a gas-liquid separator, and the gas-liquid separator is communicated with the inlet of the first compressor and the second heat exchanger respectively.

[0034] In some embodiments of the utility model, the first compressor is a variable frequency compressor, the second compressor is a fixed frequency compressor, the first water pump and the second water pump are fixed frequency water pumps respectively, and the third water pump is a variable frequency water pump.

[0035] In some embodiments of the utility model, the cascade steam heat pump unit further includes a temperature sensor, a pressure sensor and a liquid level sensor arranged on the flash tank respectively.

[0036] In some embodiments of the utility model, the first water pump is communicated with the bottom of the flash tank, the another refrigerant passage of the third heat exchanger is communicated with the middle part of the flash tank, and a steam outlet is arranged on the top of the flash tank.

[0037] In some embodiments of the utility model, the refrigerant in the first refrigerant circulation loop includes R515B refrigerant or R1234ze (E) refrigerant, and the refrigerant in the second refrigerant circulation loop includes R245fa refrigerant.

[0038] By means of the technical scheme, the utility model discloses the following advantages compared with the prior art.

[0039] The utility model discloses can solve the steam flow of high temperature heat pump steam unit preparation steam because the water temperature is too low and leads to the problem such as steam temperature being too low, can realize the function of night heat storage and daytime steam preparation through the switching of different modes, give full play to the advantage of valley electricity, make this compound high temperature steam heat pump unit more energy -conserving, further reduce operating cost. In addition, the unit can realize steam preparation from chilled water heat extraction, realize the purpose of cold and heat supply, further improve the system comprehensive energy efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained without creative labor under the premise of not paying.

[0041] Figure 1 It is the structure schematic diagram of compound steam heat pump unit of the utility model embodiment;

[0042] In the figure mark, 1, first compressor;2, second compressor;3, first heat exchanger;4, second heat exchanger;5, third heat exchanger;6, fourth heat exchanger;7, first expansion valve;8, second expansion valve;9, first water pump;10, second water pump;11, third water pump;12, flash tank;13, first water tank;14, first valve;15, second valve;16, third valve;17, fourth valve;18, fifth valve;19, sixth valve;20, steam output pipe;21, pressure reducing valve;22, economizer;23, third expansion valve;24, second water tank;25, fourth water pump;26, seventh valve;27, eighth valve;28, gas-liquid separator. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the following will make detailed description to the utility model with the specific embodiment and the drawings. In the following description, a lot of specific details are set forth in order to fully understand the utility model. But the utility model can be implemented in many other ways different from the description, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the following disclosed specific embodiments.

[0044] In the description of the utility model, the meaning of "multiple" is at least two, for example two, three, etc. Unless otherwise explicitly specified.

[0045] In the present application, unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise expressly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In the present application, unless otherwise expressly specified and limited, the first feature is "on" or "under" the second feature. The first and second features can be in direct contact, or the first and second features can be in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0047] It should be noted that when an element is referred to as "fixed to" or "provided on" another element, it can be directly on another element or there can be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element.

[0048] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0049] As shown in Figure 1 The present application provides a kind of complex steam heat pump unit, which includes first compressor 1, second compressor 2, first heat exchanger 3, second heat exchanger 4, third heat exchanger 5, fourth heat exchanger 6, first expansion valve 7, second expansion valve 8, first water pump 9, second water pump 10, third water pump 11, flash tank 12, first water tank 13.

[0050] In this example, the outlet of the first compressor 1, one refrigerant passage of the first heat exchanger 3, the first expansion valve 7, the second heat exchanger 4, the inlet of the first compressor 1 are sequentially communicated and constitute a first refrigerant circulation loop; the outlet of the second compressor 2, one refrigerant passage of the third heat exchanger 5, the second expansion valve 8, one refrigerant passage of the fourth heat exchanger 6, the inlet of the second compressor 2 are sequentially communicated and constitute a second refrigerant circulation loop; the inlet of the first water pump 9 is communicated with the flash tank 12, and the outlet of the first water pump 9 is respectively communicated with another refrigerant passage of the third heat exchanger 5 and another refrigerant passage of the first heat exchanger 3; wherein, the other refrigerant passage of the third heat exchanger 5 is also communicated with the flash tank 12, and the other refrigerant passage of the first heat exchanger 3 is also respectively communicated with the flash tank 12 and the first water tank 13; the other refrigerant passage of the fourth heat exchanger 6 is arranged in parallel with one refrigerant passage of the first heat exchanger 3; the two ends of the second water pump 10 are respectively communicated with the first water tank 13 and the other refrigerant passage of the first heat exchanger 3; the two ends of the third water pump 11 are respectively communicated with the first water tank 13 and the flash tank 12.

[0051] The first compressor 1 can be a low-temperature stage compressor, and specifically can be a variable frequency compressor, and the refrigerant in the first refrigerant circulation loop includes R515B refrigerant or R1234ze(E) refrigerant, etc.; further, the steam heat pump unit further includes a gas-liquid separator 28, the gas-liquid separator 28 is respectively communicated with the second heat exchanger 4 and the inlet of the first compressor 1, the first heat exchanger 3 is a condenser, and the second heat exchanger 4 is an evaporator.

[0052] The second compressor 2 is a high-temperature stage compressor, has a gas supplement port, and can be a fixed frequency compressor, and the refrigerant in the second refrigerant circulation loop includes R245fa refrigerant; further, the cascade steam heat pump unit further includes an economizer 22 and a third expansion valve 23, one refrigerant passage of the economizer 22 is connected in series between one refrigerant passage of the third heat exchanger 5 and the second expansion valve 8, the other refrigerant passage of the economizer 22 is respectively communicated with the gas supplement port of the second compressor 2 and the outlet of the third expansion valve 23, the inlet of the third expansion valve 23 is communicated with one refrigerant passage of the economizer 22, and through the arrangement of the economizer 22 and the third expansion valve 23, the inlet temperature of the second expansion valve 8 can be lower, which is beneficial to protect the second expansion valve 8 and avoid damage caused by too high inlet temperature; specifically, part of the refrigerant flowing through one refrigerant passage of the economizer 22 is throttled through the third expansion valve 23, the temperature is raised, then is further heated in the economizer 22, and then the refrigerant in one refrigerant passage of the economizer 22 is cooled, supercooled, and then enters the second expansion valve 8 and the third expansion valve 23 at a relatively low temperature. The third heat exchanger 5 is a condenser, and the fourth heat exchanger 6 is an evaporative condenser.

[0053] In this example, referring to Figure 1As shown, the first water pump 9 is communicated with the bottom of the flash tank 12, another refrigerant passage of the third heat exchanger 5 is communicated with the middle of the flash tank 12, and the top of the flash tank 12 is provided with a steam outlet communicated with the steam output pipe 20.

[0054] In this example, the cascade steam heat pump unit comprises a hot water mode, a steam mode, a water supplement steam mode, a first water tank constant temperature mode and a first water tank constant temperature steam mode.

[0055] When the cascade steam heat pump unit is in the hot water mode, the first compressor 1 is in the working state, the second compressor 2 is in the non-working state, the first water pump 9 and the second water pump 10 are respectively in the open state, and the third water pump 11 is in the closed state.

[0056] When the cascade steam heat pump unit is in the steam mode, the first compressor 1 and the second compressor 2 are both in the working state, the first water pump 9 is in the open state, and the second water pump 10 and the third water pump 11 are respectively in the closed state.

[0057] When the cascade steam heat pump unit is in the water supplement steam mode, the first compressor 1 and the second compressor 2 are both in the working state, the first water pump 9 and the third water pump 11 are respectively in the open state, and the second water pump 10 is in the closed state.

[0058] When the cascade steam heat pump unit is in the first water tank constant temperature mode, the first compressor 1 is in the working state, the second compressor 2 is in the non-working state, the first water pump 9 and the third water pump 11 are respectively in the closed state, and the second water pump 10 is in the open state.

[0059] When the cascade steam heat pump unit is in the first water tank constant temperature steam mode, the first compressor 1 and the second compressor 2 are both in the working state, and the first water pump 9 and the second water pump 10 are respectively in the open state.

[0060] In this example, the cascade steam heat pump unit further comprises a first valve 14, a second valve 15, a third valve 16, a fourth valve 17, a fifth valve 18 and a sixth valve 19; the two ends of the first valve 14 are respectively communicated with the outlet of the first compressor 1 and one refrigerant passage of the first heat exchanger 3; the two ends of the second valve 15 are respectively communicated with the outlet of the first compressor 1 and another refrigerant passage of the fourth heat exchanger 6; the two ends of the third valve 16 are respectively communicated with the outlet of the first water pump 9 and another refrigerant passage of the first heat exchanger 3; the two ends of the fourth valve 17 are respectively communicated with the outlet of the first water pump 9 and another refrigerant passage of the third heat exchanger 5; the two ends of the fifth valve 18 are respectively communicated with another refrigerant passage of the first heat exchanger 3 and the flash tank 12; and the two ends of the sixth valve 19 are respectively communicated with another refrigerant passage of the first heat exchanger 3 and the first water tank 13.

[0061] Further, when the cascade steam heat pump unit is in the hot water mode, the first valve 14, the third valve 16, the fifth valve 18 and the sixth valve 19 are in the open state, and the second valve 15 and the fourth valve 17 are in the closed state.

[0062] When the cascade steam heat pump unit is in the steam mode or the water-supply steam mode, the first valve 14, the third valve 16, the fifth valve 18 and the sixth valve 19 are in the closed state, and the second valve 15 and the fourth valve 17 are in the open state.

[0063] When the cascade steam heat pump unit is in the first water tank constant temperature mode, the first valve 14 and the sixth valve 19 are in the open state, and the second valve 15, the third valve 16, the fourth valve 17 and the fifth valve 18 are in the closed state.

[0064] When the cascade steam heat pump unit is in the first water tank constant temperature steam mode, the first valve 14, the second valve 15, the fourth valve 17 and the sixth valve 19 are in the open state, and the third valve 16 and the fifth valve 18 are in the closed state.

[0065] In this example, the cascade steam heat pump unit further comprises a steam output pipe 20 in communication with the flash tank 12, a pressure reducing valve 21 arranged on the steam output pipe 20, a second water tank 24, a fourth water pump 25, a seventh valve 26 and an eighth valve 27, the second water tank 24, the fourth water pump 25, the seventh valve 26 and the flash tank 12 are sequentially communicated, and the second water tank 24, the fourth water pump 25, the eighth valve 27 and the first water tank 13 are sequentially communicated; further, when the cascade steam heat pump unit is in the hot water mode or the first water tank constant temperature mode, the pressure reducing valve 21 is in the closed state; when the cascade steam heat pump unit is in the steam mode, the water-supply steam mode or the first water tank constant temperature steam mode, the pressure reducing valve 21 is in the open state.

[0066] In this example, the first valve 14 and the second valve 15 can be electrically controlled regulating valves, the third valve 16, the fourth valve 17, the fifth valve 18, the sixth valve 19, the seventh valve 26 and the eighth valve 27 can be electromagnetic valves, and the first water pump 9 and the second water pump 10 can be constant frequency water pumps, and the third water pump 11 and the fourth water pump 25 can be variable frequency water pumps.

[0067] In this example, the cascade steam heat pump unit further comprises a temperature sensor, a pressure sensor and a liquid level sensor arranged on the flash tank respectively.

[0068] This example also provides a control method of the cascade steam heat pump unit, and the control method comprises at least one of the following (a)-(e) modes:

[0069] (a) when it is detected that the liquid level in the flash tank is greater than a first preset warning liquid level and the temperature in the flash tank is greater than or equal to 90℃, the cascade steam heat pump unit is controlled to be in the steam mode.

[0070] (b) when the liquid level in the flash tank is detected to be lower than the first preset warning liquid level, and the liquid level in the first water tank is higher than the second preset warning liquid level, and the water temperature is greater than 90℃, the third water pump is opened, and the cascade steam heat pump unit is controlled to be in the make-up steam mode;

[0071] (c) when the liquid level in the flash tank is detected to be lower than the first preset warning liquid level, and the water temperature in the first water tank is lower than 90℃, the second water pump is opened, and the cascade steam heat pump unit is controlled to be in the first water tank constant temperature steam mode;

[0072] (d) when the steam production is stopped, and the liquid level in the first water tank is detected to be lower than the third preset warning liquid level and the temperature is lower than 90℃, the cascade steam heat pump unit is controlled to be in the first water tank constant temperature mode;

[0073] (e) when the time is at night, the cascade steam heat pump unit is controlled to be in the hot water mode.

[0074] The working process is roughly as follows:

[0075] (1) When it is at night and heat storage is performed by using valley electricity, the first compressor 1 works, the high-temperature and high-pressure first refrigerant releases heat at the first heat exchanger 3 (the released heat is absorbed by the water to be heated), then absorbs heat at the second heat exchanger 4 (evaporator) after throttling through the first expansion valve 7, and changes into gas at the gas-liquid separator 28, the gas refrigerant enters the first compressor 1 for compression, and the circulation is realized; the second compressor 2 is stopped, the first valve 14 is opened, the second valve 15 is closed, the third valve 16 is opened, the fourth valve 17 is closed, the fifth valve 18 and the sixth valve 19 are both opened, the pressure reducing valve 21 is closed, the first water pump 9 and the second water pump 10 are started respectively, the water in the flash tank 12 is pumped out through the first water pump 9, flows to the first heat exchanger 3 (condenser) through the third valve 13 for heat exchange (heat absorption), at the same time, the water in the first water tank 13 is pumped out through the second water pump 10, directly flows through the first heat exchanger 3 (condenser) for heat exchange (heat absorption), after being heated, part of the water returns to the flash tank 12 from the middle part of the flash tank 12 through the fifth valve 18, and the other part returns to the first water tank 13 through the sixth valve 19, so as to realize the circulation, and the water in the flash tank 12 and the first water tank 13 is heated to about 90℃ by using valley electricity at night; of course, if the water level in the flash tank 12 and the first water tank 13 is insufficient, the fourth water pump 25 can be started in advance to pump the water in the second water tank 24 to the flash tank 12 through the seventh valve 26, and to the first water tank 13 through the eighth valve 27, and after the water supplement is completed, the fourth water pump 25, the seventh valve 26 and the eighth valve 27 are closed. The above process can be the working state of the hot water mode.

[0076] (2) When the first water tank constant temperature mode of the cascade steam heat pump unit is in the first water tank constant temperature mode, which is preferably completed at night, the first compressor 1 is in the working state, the second compressor 2 is in the non-working state, the first water pump 9 and the third water pump 11 are respectively in the closed state, the second water pump 10 is in the open state, the first valve 14 and the sixth valve 19 are both open, the second valve 15, the third valve 16, the fourth valve 17, the fifth valve 18 and the seventh valve 26 are closed, and if the liquid level in the first water tank 13 is insufficient, the water in the second water tank 24 can be supplemented to the first water tank 13 through the eighth valve 27 by pre-starting the fourth water pump 25, and the fourth water pump 25 and the eighth valve 27 are closed after the water supplement is completed.

[0077] (3) When steam is generated, it can be roughly divided into three states, the first state is the steam mode, the second state is the water supplement steam mode, and the third state is the first water tank constant temperature steam mode; when in the steam mode, no water is supplemented from the first water tank 13 to the flash tank 12; when in the water supplement steam mode, water needs to be supplemented from the first water tank 13 to the flash tank 12; when in the first water tank constant temperature steam mode, according to the liquid level in the flash tank 12, if the liquid level is appropriate, no water is supplemented from the first water tank 13 to the flash tank 12, and if the liquid level is relatively low, water is supplemented from the first water tank 13 to the flash tank 12; in the above three states, the first compressor 1 and the second compressor 2 are both working;

[0078] Further, (3-1) when in the steam mode, the first compressor 1 and the second compressor 2 are both working, the first valve 14, the third valve 16, the fifth valve 18, the sixth valve 19 and the seventh valve 26 are all closed, the second valve 15 and the fourth valve 17 are both open, the pressure reducing valve 21 is open, the first water pump 9 is open, the second water pump 10 and the third water pump 11 are both closed, the high-temperature refrigerant in the first refrigerant circulation loop supplies heat to the second refrigerant circulation loop at the fourth heat exchanger 6, the high-temperature refrigerant in the second refrigerant circulation loop exchanges heat with the high-temperature water (extracted by the first water pump 9) in the flash tank 12 at the third heat exchanger 5 and heats the high-temperature water, and then returns to the flash tank 12 through the middle part of the flash tank 12 to generate steam, the steam generated in the flash tank 12 is supplied to the outside through the pressure reducing valve 21, and the temperature of the supplied steam can reach above 120 degrees Celsius;

[0079] (3-2) When in the water vapor mode, the first compressor 1 and the second compressor 2 are both working, the first valve 14, the third valve 16, the fifth valve 18, the sixth valve 19 and the seventh valve 26 are all closed, the second valve 15 and the fourth valve 17 are both opened, the pressure reducing valve 21 is opened, the first water pump 9 and the third water pump 11 are both opened, the second water pump 10 is closed, the high-temperature refrigerant in the first refrigerant circulation loop supplies heat to the second refrigerant circulation loop at the fourth heat exchanger 6, the high-temperature refrigerant in the second refrigerant circulation loop exchanges heat with the high-temperature water (extracted by the first water pump 9) in the flash tank 12 at the third heat exchanger 5 and heats the high-temperature water, and then returns to the flash tank 12 via the middle part of the flash tank 12 to produce steam, the steam produced in the flash tank 12 is supplied outward via the pressure reducing valve 21, and the temperature of the supplied steam can reach above 120 degrees Celsius; wherein the hot water in the first water tank 13 is extracted by the third water pump 11 and supplied into the flash tank 12 to ensure that the flash tank 12 has sufficient liquid level for stable steam production;

[0080] (3-3) When in the first water tank constant temperature vapor mode, the first compressor 1 and the second compressor 2 are both working, the first valve 14, the third valve 16, the fifth valve 18, the sixth valve 19 and the seventh valve 26 are all closed, the second valve 15 and the fourth valve 17 are both opened, the pressure reducing valve 21 is opened, the first water pump 9 and the second water pump 10 are opened, the high-temperature refrigerant in the first refrigerant circulation loop supplies heat to the second refrigerant circulation loop at the fourth heat exchanger 6, the high-temperature refrigerant in the second refrigerant circulation loop exchanges heat with the high-temperature water (extracted by the first water pump 9) in the flash tank 12 at the third heat exchanger 5 and heats the high-temperature water, and then returns to the flash tank 12 via the middle part of the flash tank 12 to produce steam, the steam produced in the flash tank 12 is supplied outward via the pressure reducing valve 21, and the temperature of the supplied steam can reach above 120 degrees Celsius;

[0081] Wherein, the third water pump 11 has two working states, the first is that when the liquid level in the flash tank 12 is insufficient, the third water pump 11 is opened and the hot water in the first water tank 13 is supplemented into the flash tank 12, the second is that when the liquid level in the flash tank 12 is sufficient, the third water pump 11 can be closed, at this time, it can be further judged whether the liquid level in the first water tank 13 is sufficient, if not, the water in the second water tank 24 is supplemented into the first water tank 13 by starting the fourth water pump 25, since the first water tank 13 is in the constant temperature mode, the supplemented water can be heated to the ideal temperature, so as to realize the production of steam from the hot water and realize the cold and heat supply; if the liquid level in the first water tank 13 is sufficient, only the operation of the second water pump 10 and the opening of the sixth valve 19 are needed to maintain the constant temperature of the water in the first water tank 13.

[0082] In conclusion, the utility model can solve the problems of unstable steam flow and too low steam temperature caused by too low water supplement temperature when the high-temperature heat pump steam unit generates steam.

[0083] The above examples are only for illustrating the technical concept and characteristics of the utility model, and the purpose is to enable those skilled in the art to understand the content of the utility model and implement it, and it cannot limit the protection scope of the utility model, and any equivalent changes or modifications according to the spirit and essence of the utility model shall be covered within the protection scope of the utility model.

Claims

1. A cascade steam heat pump unit, characterized by, The cascade steam heat pump unit comprises a first compressor, a second compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first expansion valve, a second expansion valve, a first water pump, a second water pump, a third water pump, a flash tank and a first water tank; The outlet of the first compressor, one refrigerant passage of the first heat exchanger, the first expansion valve, the second heat exchanger and the inlet of the first compressor are sequentially communicated and constitute a first refrigerant circulation loop; The outlet of the second compressor, one refrigerant passage of the third heat exchanger, the second expansion valve, one refrigerant passage of the fourth heat exchanger and the inlet of the second compressor are sequentially communicated and constitute a second refrigerant circulation loop; The inlet of the first water pump is communicated with the flash tank, and the outlet of the first water pump is communicated with another refrigerant passage of the third heat exchanger and another refrigerant passage of the first heat exchanger respectively; wherein the another refrigerant passage of the third heat exchanger is also communicated with the flash tank, and the another refrigerant passage of the first heat exchanger is also communicated with the flash tank and the first water tank respectively; Another refrigerant passage of the fourth heat exchanger is arranged in parallel with the one refrigerant passage of the first heat exchanger; Two ends of the second water pump are communicated with the first water tank and the another refrigerant passage of the first heat exchanger respectively; Two ends of the third water pump are communicated with the first water tank and the flash tank respectively.

2. The cascade steam heat pump unit according to claim 1, characterized in that, The cascade steam heat pump unit comprises a hot water mode, a steam mode, a water supplement steam mode, a first water tank constant temperature mode and a first water tank constant temperature steam mode; When the cascade steam heat pump unit is in the hot water mode, the first compressor is in a working state, the second compressor is in a non-working state, the first water pump and the second water pump are in an open state respectively, and the third water pump is in a closed state; When the cascade steam heat pump unit is in the steam mode, the first compressor and the second compressor are in a working state, the first water pump is in an open state, and the second water pump and the third water pump are in a closed state respectively; When the cascade steam heat pump unit is in the water supplement steam mode, the first compressor and the second compressor are in a working state, the first water pump and the third water pump are in an open state respectively, and the second water pump is in a closed state; When the cascade steam heat pump unit is in the first water tank constant temperature mode, the first compressor is in a working state, the second compressor is in a non-working state, the first water pump and the third water pump are in a closed state respectively, and the second water pump is in an open state; When the cascade steam heat pump unit is in the first water tank constant temperature steam mode, the first compressor and the second compressor are in a working state, and the first water pump and the second water pump are in an open state respectively.

3. The cascade steam heat pump unit according to claim 2, characterized in that, The cascade steam heat pump unit further comprises a first valve, a second valve, a third valve, a fourth valve, a fifth valve and a sixth valve; Two ends of the first valve are communicated with the outlet of the first compressor and the one refrigerant passage of the first heat exchanger respectively; Two ends of the second valve are respectively communicated with the outlet of the first compressor and the other refrigerant passage of the fourth heat exchanger; Two ends of the third valve are respectively communicated with the outlet of the first water pump and the other refrigerant passage of the first heat exchanger; Two ends of the fourth valve are respectively communicated with the outlet of the first water pump and the other refrigerant passage of the third heat exchanger; Two ends of the fifth valve are respectively communicated with the other refrigerant passage of the first heat exchanger and the flash tank; Two ends of the sixth valve are respectively communicated with the other refrigerant passage of the first heat exchanger and the first water tank.

4. The cascade steam heat pump unit according to claim 3, characterized in that, When the cascade steam heat pump unit is in the hot water mode, the first valve, the third valve, the fifth valve and the sixth valve are in the open state, and the second valve and the fourth valve are in the closed state; When the cascade steam heat pump unit is in the steam mode or the water supplement steam mode, the first valve, the third valve, the fifth valve and the sixth valve are in the closed state, and the second valve and the fourth valve are in the open state; When the cascade steam heat pump unit is in the first water tank constant temperature mode, the first valve and the sixth valve are in the open state, and the second valve, the third valve, the fourth valve and the fifth valve are in the closed state. When the cascade steam heat pump unit is in the first water tank constant temperature steam mode, the first valve, the second valve, the fourth valve and the sixth valve are in the open state, and the third valve and the fifth valve are in the closed state.

5. The cascade vapor pump unit according to claim 3, wherein The first valve and the second valve are respectively electrically controlled valves, and the third valve, the fourth valve, the fifth valve and the sixth valve are respectively electromagnetic valves.

6. The cascade steam heat pump unit according to claim 2, characterized in that, The cascade steam heat pump unit further comprises a steam output pipe communicated with the flash tank and a pressure reducing valve arranged on the steam output pipe; when the cascade steam heat pump unit is in the hot water mode or the first water tank constant temperature mode, the pressure reducing valve is in the closed state; when the cascade steam heat pump unit is in the steam mode, the water supplement steam mode or the first water tank constant temperature steam mode, the pressure reducing valve is in the open state.

7. The cascade vapor pump unit according to claim 1, wherein The second compressor further comprises a gas supplement port; the cascade steam heat pump unit further comprises an economizer and a third expansion valve, one refrigerant passage of the economizer is connected in series between the one refrigerant passage of the third heat exchanger and the second expansion valve, the other refrigerant passage of the economizer is respectively communicated with the gas supplement port of the second compressor and the outlet of the third expansion valve, the inlet of the third expansion valve is communicated with the one refrigerant passage of the economizer; and / or, The cascade steam heat pump unit further comprises a second water tank, a fourth water pump, a seventh valve and an eighth valve, the second water tank, the fourth water pump, the seventh valve and the flash tank are communicated in sequence, and the second water tank, the fourth water pump, the eighth valve and the first water tank are communicated in sequence.

8. The cascade vapor pump unit according to claim 1, wherein The cascade steam heat pump unit further comprises a gas-liquid separator, which is in communication with the second heat exchanger and the inlet of the first compressor respectively; and / or the first compressor is a variable frequency compressor, the second compressor is a fixed frequency compressor, the first water pump and the second water pump are fixed frequency water pumps respectively, and the third water pump is a variable frequency water pump.

9. The cascade vapor pump unit according to claim 1, wherein The cascade steam heat pump unit further comprises a temperature sensor, a pressure sensor and a liquid level sensor arranged on the flash tank respectively.

10. The cascade vapor pump unit according to claim 1, wherein The first water pump is in communication with the bottom of the flash tank, the other refrigerant passage of the third heat exchanger is in communication with the middle of the flash tank, and a steam outlet is arranged at the top of the flash tank.

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