Ventilation air methane wide enthalpy phase change cryogenic heat extraction efficient defrosting system

Abstract

The utility model discloses a ventilation air methane wide enthalpy phase change cryogenic heat extraction efficient defrosting system which comprises a heat pump unit connected to the tail end of a heat consumer, the heat pump unit is connected to a first heat exchanger, a second heat exchanger and a third heat exchanger, and the heat pump unit comprises an expansion device, an evaporator, a compressor and a condenser. The expansion device, the evaporator, the compressor and the condenser are sequentially connected through pipelines, the evaporator is connected to the first heat exchanger, the second heat exchanger and the third heat exchanger through a working medium circulating pump, and the condenser is connected to a heat consumer terminal through a heat supply circulating pump. The system has all the advantages of a rolling defrosting system, the number of valves is reduced, control is optimized, the system is simple, under the condition of the same heat exchange area, the heat exchange area of the heat exchanger can be completely used for heat extraction of ventilation air methane, the heat extraction amount of the heat exchanger is larger, and the ventilation air methane waste heat recovery system can provide more heat supply amount; and more building heating areas and shaft anti-freezing loads can be met.

Description

Technical Field

[0001] The utility model relates to the field of waste heat utilization in coal mining, and more specifically to an air-defrosting wide enthalpy phase change deep cooling heat extraction and high-efficiency defrosting system. Background Art

[0002] Currently, my country's energy source is primarily coal. Ventilation is crucial during coal mining, requiring high ventilation volumes. The temperature of mine exhaust air remains largely constant year-round, and exhaust air contains a wealth of low-temperature thermal energy. Lack of air waste heat recovery technology can be used to recover this low-temperature waste heat from mine exhaust air and apply it to heating buildings, wellhead antifreeze, and hot water for bathing in industrial sites. This technology offers significant economic and social benefits and has significant potential for widespread adoption. Currently, domestic research on exhaust air waste heat recovery focuses on inter-wall heat exchange between ethylene glycol solution and exhaust air. This technology utilizes an ethylene glycol solution circulation system, adjusting the freezing point according to the required heat, allowing for deep heat extraction from the return air. However, during the heat exchange process between the ethylene glycol solution and the exhaust air through the partitioning heat exchanger, due to the low temperature of the ethylene glycol solution, the water vapor in the exhaust air will condense on the surface of the partitioning heat exchanger to form water droplets. When the temperature of the ethylene glycol solution is lower than 0°C, the water droplets on the surface of the partitioning heat exchanger will form ice crystals, causing large-scale frost on the heat exchanger surface. This not only increases the heat transfer resistance, but also increases the air resistance on the heat exchanger surface, reducing air flow, and seriously affecting the heat exchange effect of the partitioning heat exchanger. Therefore, in the actual engineering application of the project, it is necessary to consider adding a defrost system.

[0003] In order to solve the problem of frost affecting the heat exchange efficiency of the heat exchanger during the process of heat extraction from exhaust air, the following is designed: Figure 1 The automatic defrost device shown. When only a small amount of frost remains on the heat exchanger surface, defrosting is performed by suspending the exhaust air heat pump unit. When the heat exchanger surface is severely frosted, the rolling defrost device is activated to ensure normal system operation. The rolling defrost system works as follows: When the heat exchanger surface is severely frosted and the defrost system needs to be activated, the 1# and 2# pneumatic two-way ball valves are closed, and the 1# heat exchanger stops drawing heat. Simultaneously, the 3# and 4# pneumatic two-way ball valves are opened, and the 1# heat exchanger begins defrosting. When the 1# heat exchanger finishes defrosting, the 3# and 4# pneumatic two-way ball valves are closed, and the 1# and 2# pneumatic two-way ball valves begin to open, and the 1# heat exchanger begins drawing heat. In sequence, the 2# heat exchanger stops taking heat and starts defrosting. Therefore, the purpose of defrosting all heat exchanger surfaces is achieved through the rolling defrost of the system. In addition, the rolling defrost system is used, and only 1 to 2 groups of heat exchangers are defrosted each time, which does not affect the heat collection of other heat exchangers. The heat supply of the entire exhaust air waste heat recovery system is relatively stable.

[0004] However, the rolling defrost system also has certain technical drawbacks. On the one hand, the rolling defrost system has a large number of pneumatic valves, resulting in a complex intelligent control system. Furthermore, the pneumatic valves are relatively expensive, leading to high investment costs for the defrost system. On the other hand, the exhaust air heat exchanger designed for the defrost system requires the addition of a separate defrost line. This results in a larger design area for the heat exchanger, but the area involved in actual effective heat exchange is limited because some heat exchange lines are not involved in heat exchange and only serve the defrosting process. Consequently, the heat exchanger has a large design area, high costs, and is difficult to design and manufacture, resulting in a long design, production, and processing cycle. Utility Model Content

[0005] Technical problems to be solved by the utility model

[0006] The purpose of the utility model is to provide a high-efficiency defrosting system with a wide enthalpy phase change deep cooling and heat extraction by exhaust air, so as to solve the related problems raised in the above-mentioned background technology.

[0007] The technical solution of the utility model

[0008] A high-efficiency defrosting system with wide enthalpy phase change deep cooling and heat extraction using exhausted air comprises a heat pump unit connected to a heat user terminal, the heat pump unit being connected to a first heat exchanger, a second heat exchanger and a third heat exchanger. The heat pump unit comprises an expansion device, an evaporator, a compressor and a condenser, and the expansion device, the evaporator, the compressor and the condenser are connected in sequence through pipelines. The evaporator is connected to the first heat exchanger, the second heat exchanger and the third heat exchanger through a working fluid circulation pump, and the condenser is connected to the heat user terminal through a heating circulation pump.

[0009] Preferably, a first pneumatic three-way ball valve and a second pneumatic three-way ball valve are provided on the outside of the first heat exchanger, the second heat exchanger and the third heat exchanger.

[0010] Preferably, the first pneumatic three-way ball valves on the outsides of the first heat exchanger, the second heat exchanger and the third heat exchanger are all connected by pipelines and communicated with the heat user end.

[0011] Preferably, the first heat exchanger, the second heat exchanger and the second pneumatic three-way ball valves outside the third heat exchanger are all connected by pipelines and communicated with the heat user end.

[0012] Preferably, the second pneumatic three-way ball valves outside the first heat exchanger, the second heat exchanger and the third heat exchanger are all connected through pipelines and communicated with the working medium circulation pump.

[0013] Beneficial effects of the utility model

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] 1. Optimize the defrost control system by using a pneumatic three-way ball valve to replace the original pneumatic two-way ball valve, reducing the number of valves used and simplifying control;

[0016] 2. Optimize the design of the heat exchanger system, and combine the heat extraction and defrosting systems of the heat exchanger into one heat exchange system with optimized structure and simple processing. Under the condition of equal heat extraction, it can effectively reduce the heat exchanger area and reduce investment costs.

[0017] 3. The exhaust air wide enthalpy phase change deep cooling heat extraction and high-efficiency defrost system of the present application has all the advantages of the rolling defrost system compared with the rolling defrost system. Moreover, the system reduces the number of valves, optimizes the control, and has a simple system. Under the condition of the same heat exchange area, the heat exchange area of the heat exchanger can be fully used for exhaust air heat extraction. The heat extraction capacity of the heat exchanger is greater, and the exhaust air waste heat recovery system can provide more heating capacity, which can meet the heating area of more buildings and the anti-freezing load of the wellbore. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of an existing low-pressure air wide enthalpy phase change cryogenic heat extraction and high-efficiency defrosting system;

[0019] Figure 2 This is a schematic structural diagram of a high-efficiency defrosting system with a wide enthalpy phase change and low-temperature cooling;

[0020] Figure 3 This is a partially enlarged structural schematic diagram of a low-pressure air wide enthalpy phase change deep cooling heat extraction and high-efficiency defrosting system of the utility model.

[0021] Explanation of the numbers in the figure: 1-heat pump unit, 101-expansion device, 102-evaporator, 103-compressor, 104-condenser, 2-first heat exchanger, 3-second heat exchanger, 4-third heat exchanger, 5-working fluid circulation pump, 6-heat supply circulation pump, 7-heat user terminal. DETAILED DESCRIPTION

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In the description of the present invention, “plurality” means two or more, unless otherwise clearly defined.

[0024] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "mounted / connected," and "connected" should be understood in a broad sense. For example, "connected" can mean 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 an indirect connection through an intermediate medium, or it can be internal communication between two components. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to the specific circumstances.

[0025] See also Figure 1-3 A high-efficiency defrosting system with wide enthalpy phase change and deep cooling for heat extraction using exhausted air includes a heat pump unit 1 connected to a heat user terminal 7, and the heat pump unit 1 is connected to a first heat exchanger 2, a second heat exchanger 3, and a third heat exchanger 4.

[0026] The heat pump unit 1 includes an expansion device 101, an evaporator 102, a compressor 103, and a condenser 104, and the expansion device 101, the evaporator 102, the compressor 103, and the condenser 104 are connected in sequence by pipelines. The evaporator 102 is connected to the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4 through a working fluid circulation pump 5, and the condenser 104 is connected to the heat user terminal 7 through a heating circulation pump 6.

[0027] A first pneumatic three-way ball valve and a second pneumatic three-way ball valve are installed on the outside of the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4. The first pneumatic three-way ball valves on the outside of the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4 are connected by pipelines and communicated with the heat user terminal 7.

[0028] The second pneumatic three-way ball valves on the outside of the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4 are all connected by pipelines and communicated with the heat user terminal 7. The second pneumatic three-way ball valves on the outside of the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4 are all connected by pipelines and communicated with the working medium circulation pump 5.

[0029] The high-efficiency defrost system for exhaust air wide enthalpy phase change deep cooling heat extraction described in this application optimizes the defrost control system on the basis of existing technology, and adopts a pneumatic three-way ball valve to replace the original pneumatic two-way ball valve; in addition, the design of the heat exchanger system is also optimized, and the two heat exchange systems of heat extraction and defrosting of the heat exchanger are combined into one heat exchange system.

[0030] The high-efficiency defrost system for exhaust air, wide enthalpy phase change cryogenic heating, operates as follows: When frost on the heat exchanger surfaces becomes severe and the defrost system needs to be activated, channels 1 and 2 of the 1# pneumatic three-way ball valve and channels 4 and 5 of the 2# pneumatic three-way ball valve are closed, and heat extraction on the 1# heat exchanger stops. Then, channels 2 and 3 of the 1# pneumatic three-way ball valve and channels 5 and 6 of the 2# pneumatic three-way ball valve are opened, and defrosting on the 1# heat exchanger begins. When defrosting on the 1# heat exchanger ends, channels 2 and 3 of the 1# pneumatic three-way ball valve and channels 5 and 6 of the 2# pneumatic three-way ball valve are closed, and channels 1 and 2 of the 1# pneumatic three-way ball valve and channels 4 and 5 of the 2# pneumatic three-way ball valve are opened, and heat extraction on the 1# heat exchanger resumes. Subsequently, heat extraction on the 2# heat exchanger stops and defrosts begin. Thus, through the system's rolling defrosting, all heat exchanger surfaces are defrosted.

[0031] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency defrosting system for exhaust air with wide enthalpy phase change deep cooling and heat extraction, comprising a heat pump unit (1) connected to a heat user terminal (7), the heat pump unit (1) being connected to a first heat exchanger (2), a second heat exchanger (3), and a third heat exchanger (4), characterized in that: The heat pump unit (1) comprises an expansion device (101), an evaporator (102), a compressor (103) and a condenser (104), wherein the expansion device (101), the evaporator (102), the compressor (103) and the condenser (104) are sequentially connected via pipelines; the evaporator (102) is connected to the first heat exchanger (2), the second heat exchanger (3) and the third heat exchanger (4) via a working fluid circulation pump (5); and the condenser (104) is connected to a heat user terminal (7) via a heating circulation pump (6).

2. The exhaust air wide enthalpy phase change deep cooling heat extraction and high efficiency defrosting system according to claim 1 is characterized by: A first pneumatic three-way ball valve and a second pneumatic three-way ball valve are provided on the outside of the first heat exchanger (2), the second heat exchanger (3), and the third heat exchanger (4).

3. The exhaust air wide enthalpy phase change cryogenic heat extraction and high efficiency defrosting system according to claim 2 is characterized by: The first pneumatic three-way ball valves outside the first heat exchanger (2), the second heat exchanger (3), and the third heat exchanger (4) are all connected through pipelines and communicated with the heat user terminal (7).

4. The exhaust air wide enthalpy phase change cryogenic heat extraction and high efficiency defrosting system according to claim 3 is characterized by: The first heat exchanger (2), the second heat exchanger (3), and the second pneumatic three-way ball valves outside the third heat exchanger (4) are all connected through pipelines and communicated with the heat user terminal (7).

5. The exhaust air wide enthalpy phase change cryogenic heat extraction and high efficiency defrosting system according to claim 4 is characterized by: The second pneumatic three-way ball valves outside the first heat exchanger (2), the second heat exchanger (3), and the third heat exchanger (4) are all connected through pipelines and communicated with the working medium circulation pump (5).

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