Defrosting system of low-temperature cascade steam heat pump

Abstract

The utility model discloses a defrosting system of a low-temperature cascade steam heat pump. The defrosting system comprises a low-temperature loop, a high-temperature loop, a steam loop and a controller. The low-temperature loop comprises an evaporator, a low-temperature-stage compressor, a first four-way valve, the low-temperature side of the intermediate heat exchanger and a low-temperature-stage expansion valve. The high-temperature loop comprises a high-temperature-stage compressor, a second four-way valve, the high-temperature side of the intermediate heat exchanger, the high-temperature side of the condenser, a high-temperature-stage expansion valve and a first stop valve. The steam loop comprises a flash tank, a water pump, a steam valve, a steam side of the condenser and a second stop valve; the low-temperature loop and the high-temperature loop exchange heat through the low-temperature side and the high-temperature side of the intermediate heat exchanger; the high-temperature loop and the steam loop exchange heat through the high-temperature side and the steam side of the condenser. Defrosting can be completed in a short time, fault alarms such as over-high voltage or over-low voltage are avoided, and continuity and stability of defrosting of the system are guaranteed.

Description

Technical Field

[0001] This utility model specifically relates to a defrosting system for a low-temperature cascade steam heat pump. Background Technology

[0002] Steam is widely used in industrial and commercial production, such as distillation, sterilization, cleaning, and ironing. Most steam operates at temperatures between 100 and 200°C, which is high in temperature and heat.

[0003] Steam heat pump systems are widely used to produce steam, replacing traditional fossil fuel boilers. Due to the low winter temperatures (below 0°C) and the large difference between ambient and operating temperatures, cascade systems are typically used to extend the low-temperature range to produce steam at low ambient temperatures.

[0004] When a cascade system is used for heating at low ambient temperatures (below 0°C), the evaporator section of the low-temperature stage is prone to frosting because it is below the freezing point. During defrosting, the low-temperature and high-temperature stages must be switched simultaneously, operating in opposite directions for defrosting. Because the steam produced by the high-temperature stage liquefies and generates significant heat when the system operates in reverse, the large difference in heat load between the low-temperature and high-temperature stages during simultaneous operation can cause alarms such as high suction and exhaust pressures and excessively high exhaust temperatures, easily leading to system shutdowns. Utility Model Content

[0005] To address the aforementioned technical problems, this utility model proposes a defrosting system for a low-temperature cascade steam heat pump.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows:

[0007] This utility model discloses a defrosting system for a low-temperature cascade steam heat pump, comprising: a low-temperature circuit, a high-temperature circuit, a steam circuit, and a controller;

[0008] The cryogenic circuit includes: evaporator, cryogenic stage compressor, first four-way valve, cryogenic side of intermediate heat exchanger, and cryogenic stage expansion valve;

[0009] The inlet of the first four-way valve is connected to the outlet of the cryogenic stage compressor via a return pipe. The return port of the first four-way valve is connected to the return port of the cryogenic stage compressor via a pipeline. The first outlet of the first four-way valve, the evaporator, and one end of the intermediate heat exchanger on the cryogenic side are connected sequentially via pipelines. A cryogenic expansion valve is installed on the pipeline connecting the evaporator and the cryogenic side of the intermediate heat exchanger.

[0010] The second outlet of the first four-way valve is connected to the other end of the low-temperature side of the intermediate heat exchanger via a pipeline.

[0011] The high-temperature circuit includes: a high-temperature stage compressor, a second four-way valve, the high-temperature side of the intermediate heat exchanger, the high-temperature side of the condenser, a high-temperature stage expansion valve, and a first shut-off valve;

[0012] The inlet of the second four-way valve is connected to the outlet of the high-temperature stage compressor via a return pipe, and the return port of the second four-way valve is connected to the return port of the high-temperature stage compressor via a pipeline. The first outlet of the second four-way valve is connected to one end of the high-temperature side of the intermediate heat exchanger via a pipeline.

[0013] The second outlet of the second four-way valve is connected to one end of the high-temperature side of the condenser via a pipeline.

[0014] The other end of the high-temperature side of the condenser is connected to the other end of the high-temperature side of the intermediate heat exchanger through a pipeline, and a high-temperature expansion valve is installed on the pipeline connecting the other end of the high-temperature side of the condenser to the other end of the high-temperature side of the intermediate heat exchanger.

[0015] The first shut-off valve is electrically connected to the controller and is used to control the operating status of the high-temperature compressor.

[0016] The steam circuit includes: a flash tank, a water pump, steam valves, the steam side of the condenser, and a second shut-off valve;

[0017] One end of the condenser on the steam side, the inlet of the flash tank, the condensate outlet of the flash tank, and the other end of the condenser on the steam side are connected in sequence by pipelines.

[0018] The flash tank's steam outlet outputs steam through an output pipeline, and a steam valve is used to control the opening and closing of the output pipeline;

[0019] Furthermore, the steam outlet of the flash tank is connected to the pipeline in the steam circuit through the return pipeline, which is used to transport steam back to the steam circuit. A second shut-off valve is installed on the return pipeline, which is electrically connected to the controller. The second shut-off valve is used to control the opening and closing of the return pipeline.

[0020] The water pump is installed on the pipeline of the steam circuit to transport water.

[0021] The water pump inlet is connected to the water supply pipeline to provide makeup water for the steam circuit;

[0022] The low-temperature circuit and the high-temperature circuit exchange heat through the low-temperature side and the high-temperature side of the intermediate heat exchanger.

[0023] The high-temperature circuit and the steam circuit exchange heat through the high-temperature side and the steam side of the condenser.

[0024] Based on the above technical solution, the following improvements can be made:

[0025] As a preferred option, the steam outlet of the flash tank is connected to the suction port of the water pump via a return pipeline.

[0026] As a preferred option, the water pump is a water pump with an ejector function, which can transport water flow and can also draw in steam.

[0027] As a preferred option, the water pump is installed on the pipeline connecting the condensate outlet of the flash tank to the other end of the steam side of the condenser.

[0028] As a preferred embodiment, the steam circuit also includes: a steam heat exchanger;

[0029] The condensate outlet of the flash tank is connected to one end of the steam side of the steam heat exchanger via a pipeline, and the other end of the steam side of the steam heat exchanger is connected to the other end of the steam side of the condenser via a pipeline.

[0030] The steam outlet of the flash tank is connected to one end of the drain side of the steam heat exchanger via a return pipeline, and the other end of the drain side of the steam heat exchanger is connected to the drain pipeline.

[0031] As a preferred embodiment, the water pump is installed on the pipeline connecting the other end of the steam side of the steam heat exchanger and the other end of the steam side of the condenser.

[0032] As a preferred embodiment, a pressure sensor is installed on the return pipe that connects to the exhaust port of the cryogenic compressor, and the pressure sensor is electrically connected to the controller.

[0033] This utility model discloses a defrosting system for a low-temperature cascade steam heat pump. When the defrosting conditions are met, it can complete defrosting in a short time without causing fault alarms such as excessively high pressure or excessively low pressure, thus ensuring the continuity and stability of the system's defrosting process. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is one of the structural schematic diagrams of the defrosting system of the low-temperature cascade steam heat pump provided in the embodiment of this utility model.

[0036] Figure 2 The second schematic diagram of the defrosting system of the low-temperature cascade steam heat pump provided in this embodiment of the present invention.

[0037] Wherein: 1-Controller, 21-Evaporator, 22-Low-temperature stage compressor, 23-First four-way valve, 24-Low-temperature side of intermediate heat exchanger, 25-Low-temperature stage expansion valve, 26-Pressure sensor, 31-High-temperature stage compressor, 32-Second four-way valve, 33-High-temperature side of intermediate heat exchanger, 34-High-temperature side of condenser, 35-High-temperature stage expansion valve, 36-First shut-off valve, 41-Flash tank, 42-Water pump, 43-Steam valve, 44-Steam side of condenser, 45-Second shut-off valve, 51-Steam side of steam heat exchanger, 52-Drainage side of steam heat exchanger. Detailed Implementation

[0038] The preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0040] Meanwhile, expressions such as "first" and "second" are used only to distinguish between multiple configurations, rather than to restrict the order between configurations or other features.

[0041] Furthermore, the expression "includes" is an "open-ended" expression, which only means that the corresponding component exists and should not be interpreted as excluding additional components.

[0042] To achieve the objectives of this utility model, some embodiments of a defrosting system for a low-temperature cascade steam heat pump, such as... Figure 1 As shown, the defrosting system includes: a low-temperature circuit, a high-temperature circuit, a steam circuit, and a controller 1;

[0043] The low-temperature circuit includes: evaporator 21, low-temperature stage compressor 22, first four-way valve 23, low-temperature side of intermediate heat exchanger 24, and low-temperature stage expansion valve 25;

[0044] The inlet a0 of the first four-way valve 23 is connected to the outlet of the low-temperature stage compressor 22 via a return pipe. The return port a3 of the first four-way valve 23 is connected to the return port of the low-temperature stage compressor 22 via a pipeline. The first outlet a1 of the first four-way valve 23, the evaporator 21, and one end of the low-temperature side 24 of the intermediate heat exchanger are sequentially connected via pipelines. A low-temperature expansion valve is installed on the pipeline connecting the evaporator 21 and the low-temperature side 24 of the intermediate heat exchanger.

[0045] The second outlet a2 of the first four-way valve 23 is connected to the other end of the low-temperature side 24 of the intermediate heat exchanger through a pipeline;

[0046] A pressure sensor 26 is installed on the return pipe that connects to the exhaust port of the cryogenic compressor 22, and the pressure sensor 26 is electrically connected to the controller 1.

[0047] The high-temperature circuit includes: a high-temperature stage compressor 31, a second four-way valve 32, a high-temperature side of an intermediate heat exchanger 33, a high-temperature side of a condenser 34, a high-temperature stage expansion valve 35, and a first shut-off valve 36.

[0048] The inlet b0 of the second four-way valve 32 is connected to the outlet of the high-temperature stage compressor 31 through a return pipe; the return port b3 of the second four-way valve 32 is connected to the return port of the high-temperature stage compressor 31 through a pipeline; and the first outlet b1 of the second four-way valve 32 is connected to one end of the high-temperature side 33 of the intermediate heat exchanger through a pipeline.

[0049] The second outlet b2 of the second four-way valve 32 is connected to one end of the high-temperature side 34 of the condenser via a pipeline.

[0050] The other end of the high-temperature side 34 of the condenser is connected to the other end of the high-temperature side 33 of the intermediate heat exchanger through a pipeline, and a high-temperature expansion valve 35 is installed on the pipeline connecting the other end of the high-temperature side 34 of the condenser to the other end of the high-temperature side 33 of the intermediate heat exchanger.

[0051] The first shut-off valve 36 is electrically connected to the controller 1 and is used to control the working state of the high-temperature compressor 31.

[0052] The steam circuit includes: a flash tank 41, a water pump 42, a steam valve 43, a steam side of the condenser 44, and a second shut-off valve 45;

[0053] One end of the steam side 44 of the condenser, the inlet of the flash tank 41, the condensate outlet of the flash tank 41, and the other end of the steam side 44 of the condenser are connected in sequence by pipelines.

[0054] The steam outlet of the flash tank 41 outputs steam through the output pipeline, and the steam valve 43 is used to control the opening and closing of the output pipeline;

[0055] Furthermore, the steam outlet of the flash tank 41 is connected to the pipeline in the steam circuit through the return pipeline, which is used to transport steam back to the steam circuit. A second shut-off valve 45 is installed on the return pipeline. The second shut-off valve 45 is electrically connected to the controller 1 and is used to control the opening and closing of the return pipeline.

[0056] Water pump 42 is installed on the pipeline of the steam circuit for transporting water.

[0057] The inlet of water pump 42 is connected to the water supply pipeline to provide makeup water for the steam circuit;

[0058] The low-temperature circuit and the high-temperature circuit exchange heat through the low-temperature side 24 and the high-temperature side 33 of the intermediate heat exchanger.

[0059] The high-temperature circuit and the steam circuit exchange heat through the high-temperature side 34 and the steam side 44 of the condenser.

[0060] In order to further optimize the implementation effect of this utility model, in some other embodiments, the remaining features are the same, except that the steam outlet of the flash tank 41 is connected to the air intake of the water pump 42 through a return pipeline.

[0061] Furthermore, the water pump 42 is a water pump 42 with ejector function (or a water pump 42 with ejector attachment), which can transport water flow and can draw in steam.

[0062] Furthermore, the water pump 42 is installed on the pipeline connecting the condensate outlet of the flash tank 41 to the other end of the steam side 44 of the condenser.

[0063] The workflow of this utility model is briefly described as follows:

[0064] When this invention operates normally at low ambient temperatures:

[0065] Low-temperature circuit: The refrigerant absorbs heat through the evaporator 21, enters the low-temperature stage compressor 22 for compression, and is discharged to the low-temperature side 24 of the intermediate heat exchanger. It then expands through the low-temperature stage expansion valve 25 and re-enters the evaporator 21 to achieve low-temperature stage circulation.

[0066] High-temperature circuit: The refrigerant absorbs heat from the high-temperature side 33 of the intermediate heat exchanger, enters the high-temperature stage compressor 31 for compression, and is discharged to the high-temperature side 34 of the condenser. It then expands through the high-temperature stage expansion valve 35 and re-enters the high-temperature side 33 of the intermediate heat exchanger, thus realizing the high-temperature stage cycle.

[0067] Steam circuit: Water absorbs heat from the steam side 44 of the condenser and flows into the flash tank 41. The steam valve 43 on the output pipeline expands and throttles, generating steam. The condensate and makeup water generated in the flash tank 41 are transported by the water pump 42 to achieve steam circulation. At this time, the controller 1 controls the second shut-off valve 45 to close.

[0068] When the evaporator 21 is frosted at a low ambient temperature, the defrosting process is as follows: Low temperature circuit: The refrigerant enters the evaporator 21, expands through the low temperature stage expansion valve 25, and is discharged to the low temperature side 24 of the intermediate heat exchanger. After being compressed by the low temperature stage compressor 22, it releases heat from the evaporator 21, realizing the low temperature stage reverse heating defrosting cycle.

[0069] High-temperature circuit: The refrigerant enters the high-temperature side 33 of the intermediate heat exchanger, expands through the high-temperature stage expansion valve 35, and is discharged to the condenser. It is then compressed by the high-temperature stage compressor 31 and released from the intermediate heat exchanger to achieve a high-temperature stage reverse heating cycle.

[0070] Steam circuit: Controller 1 controls the second shut-off valve 45 to open, and the steam generated by the flash tank 41 is transported to the suction port of the water pump 42 through the return pipeline. The water pump 42 delivers water through the steam side 44 of the condenser to release heat, realizing the steam liquefaction and heat release cycle. The water generated in the intermediate process is discharged through the drain pipe.

[0071] When the low-temperature circuit reaches the defrosting condition, the controller 1 can control the speed of the low-temperature stage compressor 22 to quickly rise to the maximum frequency.

[0072] This invention sets a high-pressure operating range for the low-temperature stage and controls the on / off of the first shut-off valve 36 via a signal from the controller 1, so that the high-temperature stage compressor 31 operates between 10-100% load, ensuring continuous heat balance for all intermediate components, completing defrosting in the shortest possible time, preventing fault alarms such as excessively high or low pressure, and ensuring the continuity and stability of the system defrosting.

[0073] Furthermore, the second shut-off valve 45 between the steam and water pump 42 is controlled by the controller 1. During defrosting, the second shut-off valve 45 is opened, allowing steam to bypass and the water pump 42 to draw in steam; during normal operation, the second shut-off valve 45 is closed.

[0074] To further optimize the implementation effect of this utility model, in some other embodiments, the remaining technical features are the same, the difference being that, for example... Figure 2 As shown, the steam circuit also includes: a steam heat exchanger;

[0075] The condensate outlet of the flash tank 41 is connected to one end of the steam side 51 of the steam heat exchanger via a pipeline, and the other end of the steam side 51 of the steam heat exchanger is connected to the other end of the steam side 44 of the condenser via a pipeline.

[0076] The steam outlet of the flash tank 41 is connected to one end of the drain side 52 of the steam heat exchanger via a return pipeline, and the other end of the drain side 52 of the steam heat exchanger is connected to the drain pipeline.

[0077] Furthermore, the water pump 42 is installed on the pipeline connecting the other end of the steam side 51 of the steam heat exchanger and the other end of the steam side of the condenser.

[0078] In this embodiment, a steam heat exchanger is used to achieve defrosting.

[0079] During defrosting, controller 1 opens the second shut-off valve 45, allowing heat exchange between the steam heat exchanger and the steam circuit. It is important to note that when using this structure for defrosting, the water supply circuit of water pump 42 needs to be shut off.

[0080] In summary, this utility model discloses a defrosting system for a low-temperature cascade steam heat pump. When defrosting conditions are met, defrosting can be completed in a short time without causing fault alarms such as excessively high pressure or excessively low pressure, thus ensuring the continuity and stability of the system's defrosting process.

[0081] In the description of this utility model, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "other end", "upper", "side", "top", "inner", "front", "center", "both ends", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0082] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications may be made to this utility model without departing from its spirit and scope. All such changes and modifications fall within the scope of protection of this utility model as defined by the appended claims and their equivalents.

[0084] The control method of this utility model is to control the device by manually starting and stopping the switch. The wiring diagram of the power element and the supply of power are common knowledge in the field. Since this utility model is mainly used to protect mechanical devices, the control method and wiring layout will not be explained in detail.

Claims

1. A defrosting system for a low-temperature cascade steam heat pump, characterized in that, include: Low-temperature circuit, high-temperature circuit, steam circuit, and controller; The cryogenic circuit includes: an evaporator, a cryogenic stage compressor, a first four-way valve, the cryogenic side of an intermediate heat exchanger, and a cryogenic stage expansion valve; The inlet of the first four-way valve is connected to the outlet of the cryogenic compressor via a return pipe, and the return port of the first four-way valve is connected to the return port of the cryogenic compressor via a pipeline. The first outlet of the first four-way valve, the evaporator, and one end of the intermediate heat exchanger on the cryogenic side are sequentially connected via pipelines. A cryogenic expansion valve is installed on the pipeline connecting the evaporator and the end of the intermediate heat exchanger on the cryogenic side. The second outlet of the first four-way valve is connected to the other end of the low-temperature side of the intermediate heat exchanger via a pipeline; The high-temperature circuit includes: a high-temperature stage compressor, a second four-way valve, a high-temperature side of an intermediate heat exchanger, a high-temperature side of a condenser, a high-temperature stage expansion valve, and a first shut-off valve; The inlet of the second four-way valve is connected to the outlet of the high-temperature stage compressor via a return pipe, the return port of the second four-way valve is connected to the return port of the high-temperature stage compressor via a pipeline, and the first outlet of the second four-way valve is connected to one end of the high-temperature side of the intermediate heat exchanger via a pipeline. The second outlet of the second four-way valve is connected to one end of the high-temperature side of the condenser via a pipeline. The other end of the high-temperature side of the condenser is connected to the other end of the high-temperature side of the intermediate heat exchanger through a pipeline, and a high-temperature expansion valve is installed on the pipeline connecting the other end of the high-temperature side of the condenser to the other end of the high-temperature side of the intermediate heat exchanger. The first shut-off valve is electrically connected to the controller and is used to control the operating status of the high-temperature compressor. The steam circuit includes: a flash tank, a water pump, a steam valve, the steam side of the condenser, and a second shut-off valve; One end of the condenser's steam side, the inlet of the flash tank, the condensate outlet of the flash tank, and the other end of the condenser's steam side are connected in sequence via pipelines. The flash tank's steam outlet outputs steam through an output pipeline, and the steam valve is used to control the opening and closing of the output pipeline; Furthermore, the steam outlet of the flash tank is connected to the pipeline in the steam circuit through a return pipeline for transporting steam back to the steam circuit. A second shut-off valve is installed on the return pipeline, which is electrically connected to the controller and is used to control the opening and closing of the return pipeline. The water pump is installed on the pipeline of the steam circuit and is used to transport water. The water pump's inlet is connected to the water supply pipeline to provide makeup water for the steam circuit; The low-temperature circuit and the high-temperature circuit exchange heat through the low-temperature side and the high-temperature side of the intermediate heat exchanger. The high-temperature circuit and the steam circuit exchange heat through the high-temperature side and the steam side of the condenser.

2. The defrosting system according to claim 1, characterized in that, The steam outlet of the flash tank is connected to the air intake of the water pump via a return pipeline.

3. The defrosting system according to claim 2, characterized in that, The water pump is a water pump with an ejector function, which can transport water flow and can also draw in steam.

4. The defrosting system according to claim 3, characterized in that, The water pump is installed on the pipeline connecting the condensate outlet of the flash tank to the other end of the steam side of the condenser.

5. The defrosting system according to claim 1, characterized in that, The steam circuit also includes: a steam heat exchanger; The condensate outlet of the flash tank is connected to one end of the steam side of the steam heat exchanger via a pipeline, and the other end of the steam side of the steam heat exchanger is connected to the other end of the steam side of the condenser via a pipeline. The steam outlet of the flash tank is connected to one end of the drain side of the steam heat exchanger via a return pipeline, and the other end of the drain side of the steam heat exchanger is connected to a drain pipeline.

6. The defrosting system according to claim 5, characterized in that, The water pump is installed on the pipeline connecting the other end of the steam side of the steam heat exchanger and the other end of the steam side of the condenser.

7. The defrosting system according to any one of claims 1-6, characterized in that, A pressure sensor is installed on the return pipe that communicates with the exhaust port of the cryogenic compressor, and the pressure sensor is electrically connected to the controller.

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