Triple co-generation system combining methane-fired boiler and air source heat pump

Abstract

The utility model discloses a methane-fired boiler and air source heat pump combined triple co-generation system which comprises a methane combustion device, a boiler hot water loop and a heat pump refrigerant loop. In winter, outdoor air entering the heat pump air handling unit is preheated through smoke heat recovery of the methane-fired boiler, and the operation efficiency of the air source heat pump is improved; when the air source heat pump needs to be defrosted, heat released by combustion of the biogas is used for heating a refrigerant, and hot gas bypass defrosting of the air source heat pump is achieved; in summer, the heat exchanger connected with the refrigerant loop is used for preheating water in the hot water pipeline, and then the hot water is reheated through heating of the methane-fired boiler and the boiler smoke heat recovery process in sequence, so that domestic hot water is supplied, and multifunctionality and high efficiency of the heat pump system are achieved. And meanwhile, the sustainability and environmental friendliness of energy sources are considered, and the energy consumption is saved and utilized.

Description

Technical Field

[0001] This utility model relates to the field of design and manufacturing technology of refrigeration and heat pump air conditioning systems, specifically a combined air source heat pump tri-generation system for a biogas boiler. Background Technology

[0002] Air source heat pumps are heating and cooling devices characterized by energy saving, environmental protection, safety, and flexibility. They use air as a low-grade heat source, and because air is inexhaustible and air source heat pump devices are relatively easy to install and use, they have received widespread attention. Although air source heat pumps are being used more and more widely in my country's urban development, especially in the Yangtze River basin, their operation during winter heating is not ideal.

[0003] Currently, air source heat pumps encounter two main problems in application: First, their low-temperature adaptability; as ambient temperature decreases, the heating capacity and coefficient of performance (COP) of air source heat pumps decline. Second, there is the issue of frost formation on the outdoor heat exchanger surface. In the initial stage of frost formation, frost crystals can act as fins, thereby enhancing heat exchange. However, over time, water vapor in the air continues to penetrate the frost crystals, causing the frost layer to solidify and thicken, forming a continuous frost layer. Because the frost layer is a porous material composed of ice crystals and air, it has a low effective thermal conductivity. Therefore, the presence of the frost layer not only increases heat exchange resistance and reduces the heat transfer coefficient but also blocks air-side channels, increasing flow resistance, and in severe cases, even causing the system to malfunction. To ensure the efficient and stable operation of air source heat pumps in winter, timely defrosting of the outdoor heat exchanger is necessary.

[0004] Air source heat pumps can be defrosted using various methods, such as electric defrosting, reverse circulation defrosting, and hot gas bypass defrosting. However, traditional defrosting methods can have different negative impacts on the operation of the heat pump and the indoor environment while achieving defrosting. Electric defrosting increases the extra work done by the system, reverse circulation defrosting increases the work done by the compressor and reduces indoor thermal comfort, while hot gas bypass consumes the system's energy and reduces indoor thermal comfort.

[0005] Biogas, as a renewable energy source, is a combustible gas produced through the fermentation of microorganisms under anaerobic conditions. Biogas is typically produced by the anaerobic fermentation of organic matter such as human and livestock manure, straw, and sewage. It contains a large amount of methane and can be used for cooking, heating, and lighting. Utilizing biogas to power the defrosting process is an energy-saving method.

[0006] Therefore, there is an urgent need for a combined air source heat pump and coal-fired boiler system to solve the problem of reduced thermal efficiency of air source heat pumps in winter due to frost formation. Utility Model Content

[0007] To address the shortcomings of existing technologies, this utility model discloses a combined air source heat pump and combined heat and power system for a biogas boiler, which solves the problems mentioned in the background art and is of great significance for saving energy and improving the efficient operation of air source heat pumps.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a biogas combustion module, a boiler hot water circuit, and a heat pump refrigerant circuit, comprising a biogas combustion module, a boiler hot water circuit, and a heat pump refrigerant circuit; the biogas combustion module comprises an anaerobic biogas digester, a biogas collection device, and a biogas combustion boiler connected in sequence; the boiler hot water circuit comprises a main circulation circuit consisting of a water pump, a biogas combustion boiler, a first three-way valve, and a first heat exchanger connected in sequence via pipes, wherein the first port of the first three-way valve is connected to a gate valve, a second heat exchanger, and a hot water storage tank via pipes, and the outlet of the hot water storage tank is connected to a fourth three-way valve; the heat pump refrigerant circuit comprises a compressor, a four-way valve, an indoor unit, a throttling device, a second three-way valve, an outdoor unit, and a third three-way valve connected via pipes, wherein the first port of the third three-way valve is connected to the first heat exchanger to form a refrigerant bypass pipeline.

[0009] Preferably, the boiler hot water circuit is provided with a water tank connected to the inlet of the first heat exchanger, and the hot water storage tank is connected to the outdoor fresh air duct through the second heat exchanger.

[0010] Preferably, in the heat pump refrigerant circuit, the compressor outlet is connected to the first input terminal of the four-way valve, the inlet is connected to the second output terminal of the four-way valve, the first output terminal of the four-way valve is connected to the indoor unit and then connected in series with the throttling device and the third port of the second three-way valve, the first port of the second three-way valve is connected to the outdoor unit and then returns to the second input terminal of the four-way valve through the second port of the third three-way valve.

[0011] Preferably, the third port of the first three-way valve is connected to the outlet of the biogas boiler, the second port of the first three-way valve is connected to the inlet side of the first heat exchanger, and the first port of the first three-way valve is connected to the inlet of the hot water storage tank through a gate valve.

[0012] Preferably, the first port of the third three-way valve is connected to the refrigerant channel outlet of the first heat exchanger, and the third port of the third three-way valve is connected to the second input end of the four-way valve to form a loop.

[0013] Preferably, the flue gas outlet pipe of the biogas boiler passes through the hot water storage tank to form a flue gas heat exchange structure.

[0014] Preferably, the refrigerant bypass pipeline includes a straight pipeline between the second port of the second three-way valve and the first port of the third three-way valve, and the pipeline is provided with a refrigerant passage for the first heat exchanger.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] 1. In this utility model, the air source heat pump uses biogas as a renewable and clean energy source to provide heat to the refrigerant to achieve the purpose of hot gas bypass defrosting. This not only saves energy and protects the environment, but also avoids the outdoor unit heat exchanger from frosting in winter, which affects the thermal efficiency and improves the heat exchanger's heat exchange capacity.

[0017] 2. In this utility model, when the air source heat pump is running in summer for cooling, the first heat exchanger is used as a condenser to transfer the heat released by the refrigerant to the water in the hot water pipe. At the same time, a biogas boiler can be used to produce hot water to supply domestic hot water.

[0018] 3. In this utility model, the air source heat pump uses the flue gas after combustion in the biogas boiler to recover heat through the hot water storage tank. In winter, the recovered heat can be used to preheat the fresh air of the air conditioner, thereby avoiding frost on the heat exchanger and saving energy. At the same time, the hot water storage tank can supply domestic hot water. In summer, all the heat recovered by the hot water storage tank is used for domestic hot water supply. Attached Figure Description

[0019] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0020] In the attached diagram:

[0021] Figure 1 This is a schematic diagram of the structure of the combined air source heat pump and combined heat and power system for a biogas boiler;

[0022] Labels in the diagram: 1. Anaerobic biogas digester; 2. Biogas collection device; 3. Biogas boiler; 4. Water pump; 5. First three-way valve; 5a. First port of the first three-way valve; 5b. Second port of the first three-way valve; 5c. Third port of the first three-way valve; 6. First heat exchanger; 7. Water tank; 8. Compressor; 9. Four-way valve; 9a. First input terminal of the four-way valve; 9b. First output terminal of the four-way valve; 9d. Second input terminal of the four-way valve; 9c. Second output terminal of the four-way valve; 10. Indoor unit; 11. Throttling device; 12. Second three-way valve Valve; 12a, First port of the second three-way valve; 12b, Second port of the second three-way valve; 12c, Third port of the second three-way valve; 13, Outdoor unit; 14, Third three-way valve; 14a, First port of the third three-way valve; 14b, Second port of the third three-way valve; 14c, Third port of the third three-way valve; 15, Hot water storage tank; 16, Fourth three-way valve; 16a, First port of the fourth three-way valve; 16b, Second port of the fourth three-way valve; 16c, Third port of the fourth three-way valve; 17, Second heat exchanger; 18, Gate valve. Detailed Implementation

[0023] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] Example: Figure 1 As shown, this utility model provides a combined air-source heat pump and combined heat and power system for a biogas-fired boiler, comprising a biogas combustion module, a boiler hot water circuit, and a heat pump refrigerant circuit. The specific structure and connection method are as follows:

[0025] 1) Biogas combustion module;

[0026] The biogas combustion device includes an anaerobic biogas digester 1, a biogas collection device 2, and a biogas boiler 3.

[0027] The anaerobic biogas digester 1, biogas collection device 2, and biogas boiler 3 are connected in sequence.

[0028] 2) Boiler hot water circuit;

[0029] The boiler hot water circuit includes a water pump 4, a biogas boiler 3, a first three-way valve 5, a first heat exchanger 6, a water tank 7, a hot water storage tank 15, a fourth three-way valve 16, and a second heat exchanger 17.

[0030] The outlet of the water pump 4 is connected to the biogas boiler 3, the biogas boiler is connected to the third port 5c of the first three-way valve 5, the second port 5b of the first three-way valve is connected to the first heat exchanger 6, the first heat exchanger is connected to the inlet of the water pump 4, the first port 5a of the first three-way valve is connected to the gate valve 18 and the second heat exchanger 17, the gate valve 17 and the second heat exchanger 17 are connected to the hot water storage tank 15, the outlet of the hot water storage tank is connected to the fourth three-way valve 16, and the water tank 7 is connected to the inlet side of the first heat exchanger 6.

[0031] 3) Heat pump refrigerant circuit

[0032] The heat pump refrigerant circuit includes a compressor 8, a four-way valve 9, an indoor unit 10, a throttling device 11, a second three-way valve 12, an outdoor unit 13, a third three-way valve 14, and a refrigerant bypass pipeline, wherein the refrigerant bypass pipeline is connected to the first heat exchanger 6.

[0033] The compressor 8 has its outlet connected to the first input terminal 9a of a four-way valve, its inlet connected to the second output terminal 9c of a four-way valve, its first output terminal 9b connected to the indoor unit 10, its indoor unit 10 connected to a throttling device 11, its throttling device 11 connected to the third port 12c of a second three-way valve, its first port 12a connected to the outdoor unit 13, its outdoor unit 13 connected to the second port 14b of a third three-way valve, its third port 14c connected to the second input terminal 9d of a four-way valve, its first port 14a connected to the first heat exchanger 6, and the other end of the first heat exchanger 6 connected to the second port 12b of the second three-way valve. The refrigerant bypass pipeline is the pipeline between the second port 12b of the second three-way valve and the first port 14a of the third three-way valve.

[0034] The operating modes of the air source heat pump air conditioning system are as follows:

[0035] 1) During winter heating operation:

[0036] The biogas collection device 2 collects biogas from the anaerobic biogas digester 1 and supplies it to the biogas boiler 3. The high-temperature flue gas from the biogas boiler is discharged to the outside through the hot water storage tank 15. The hot water in the hot water storage tank 15 exchanges heat with the outdoor fresh air through the second heat exchanger 17 to preheat the fresh air. The water passing through the second heat exchanger 17 returns to the hot water storage tank 15 to complete the loop. Part of the hot water in the hot water storage tank 15 is used to supply domestic hot water.

[0037] In the refrigerant circuit, the refrigerant in compressor 8 passes sequentially through four-way valve 9, indoor unit 10, throttling device 11, second three-way valve 12, outdoor unit 13 and third three-way valve 14, and then returns to compressor 8 through four-way valve 9 to complete the heating cycle.

[0038] 2) During winter defrosting operation:

[0039] The biogas collection device 2 collects biogas from the anaerobic biogas digester 1 and supplies it to the biogas boiler 3. The water in the hot water circuit enters the biogas boiler 3 through the water pump 4 and is heated into hot water. Then, it enters the first heat exchanger 6 through the first three-way valve 5 to release heat. The water then flows out of the first heat exchanger 6 and enters the water pump 4 to complete the cycle. The refrigerant in the refrigerant bypass circuit enters the first heat exchanger 6, absorbs heat, and becomes high-temperature gas. It then enters the outdoor unit 13 through the second three-way valve 12 to participate in defrosting. The refrigerant flowing out of the outdoor unit 13 returns to the first heat exchanger 6 through the third three-way valve 14 to complete the defrosting cycle.

[0040] 3) During summer cooling and refrigeration operation:

[0041] In the refrigerant circuit, the refrigerant passes through the compressor 8 and the four-way valve 9, enters the refrigerant bypass pipeline through the third three-way valve 14, releases heat through the first heat exchanger 6, and then enters the throttling device 11 through the second three-way valve 12. After releasing cooling capacity through the indoor unit 10, the refrigerant returns to the compressor 8 through the four-way valve 9, completing the refrigeration cycle.

[0042] 4) During summer hot water supply operation:

[0043] In the refrigerant circuit, the refrigerant passes through the compressor 8 and the four-way valve 9, enters the refrigerant bypass pipeline through the third three-way valve 14, and then releases heat through the first heat exchanger 6.

[0044] In the boiler hot water circuit, water in water tank 7 enters the first heat exchanger 6, absorbs the energy released by the refrigerant and exchanges heat with the water. The water preheated by the first heat exchanger 6 enters the water pump 4 and flows into the biogas boiler 3. The biogas collection device 2 collects biogas from the anaerobic biogas digester 1 and sends it to the biogas boiler 3. The boiler combustion 3 heats the water flowing into the boiler. The heated hot water enters the hot water storage tank 15 through the fourth three-way valve 16 and the gate valve 18, transfers heat to the water in the hot water storage tank 15, and then returns to the first heat exchanger 6 through the fourth three-way valve 16 to participate in the circulation.

[0045] The flue gas discharged from the biogas boiler 3 is discharged to the outside through the hot water storage tank 15. The flue gas releases heat in the hot water storage tank 15 to heat the water in the tank. The water in the hot water storage tank 15 is used for domestic hot water.

[0046] In practical use: In winter, the energy released by the combustion of the biogas boiler 3 is transferred to the refrigerant in the bypass pipeline of the outdoor unit 13 by the heat exchanger, thereby realizing hot gas bypass defrosting. At the same time, the waste heat of the flue gas of the biogas boiler 3 is recovered by the heat exchanger to preheat the fresh air, thereby realizing defrosting of the heat exchanger of the outdoor unit 13 in winter and increasing the thermal efficiency of the heat pump system. In summer, the heat exchanger connected to the outdoor unit 13 acts as the condenser of the air source heat pump, and the released heat is used to preheat the water in the hot water pipeline. The preheated water then enters the biogas boiler and becomes high-temperature water before entering the hot water storage tank 15. The waste heat of the flue gas in the biogas boiler 3 is recovered by the hot water storage tank 15, and the hot water in the hot water storage tank 15 can be used to supply domestic hot water.

[0047] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A combined air-source heat pump and combined heat and power system for a biogas boiler, characterized in that: The system includes a biogas combustion module, a boiler hot water circuit, and a heat pump refrigerant circuit. The biogas combustion module includes an anaerobic biogas digester (1), a biogas collection device (2), and a biogas boiler (3) connected in sequence. The boiler hot water circuit includes a main circulation circuit consisting of a water pump (4), a biogas boiler (3), a first three-way valve (5), and a first heat exchanger (6) connected in sequence via pipes. The first port (5a) of the first three-way valve (5) is connected to a gate valve (18), a second heat exchanger (17), and a hot water storage tank (15) via pipes. The outlet of the hot water storage tank (15) is connected to a fourth three-way valve (16). The heat pump refrigerant circuit includes a compressor (8), a four-way valve (9), an indoor unit (10), a throttling device (11), a second three-way valve (12), an outdoor unit (13), and a third three-way valve (14) connected via pipes. The first port (14a) of the third three-way valve (14) is connected to the first heat exchanger (6) to form a refrigerant bypass pipeline.

2. The combined air-source heat pump and combined heat and power system for a biogas boiler according to claim 1, characterized in that: The boiler hot water circuit is equipped with a water tank (7) connected to the inlet of the first heat exchanger (6), and the hot water storage tank (15) is connected to the outdoor fresh air channel through the second heat exchanger (17).

3. The combined air-source heat pump and combined heat and power system for a biogas boiler according to claim 1, characterized in that: In the heat pump refrigerant circuit, the compressor (8) outlet is connected to the first input terminal (9a) of the four-way valve, and the inlet is connected to the second output terminal (9c) of the four-way valve. The first output terminal (9b) of the four-way valve is connected to the indoor unit (10) and then connected in series with the throttling device (11) and the third port (12c) of the second three-way valve. The first port (12a) of the second three-way valve is connected to the outdoor unit (13) and then returns to the second input terminal (9d) of the four-way valve through the second port (14b) of the third three-way valve.

4. The combined air-source heat pump and combined heat and power system for a biogas boiler according to claim 1, characterized in that: The first three-way valve (5) has its third port (5c) connected to the outlet of the biogas boiler (3), its second port (5b) connected to the inlet side of the first heat exchanger (6), and its first port (5a) connected to the inlet of the hot water storage tank (15) via a gate valve (18).

5. A combined air-source heat pump and combined heat and power system for a biogas boiler according to claim 1, characterized in that: The first port (14a) of the third three-way valve is connected to the refrigerant channel outlet of the first heat exchanger (6), and the third port (14c) of the third three-way valve is connected to the second input end (9d) of the four-way valve to form a loop.

6. The combined air source heat pump and combined heat and power system for a biogas boiler according to claim 1, characterized in that: The flue gas outlet pipe of the biogas boiler (3) passes through the hot water storage tank (15) to form a flue gas heat exchange structure.

7. A combined air-source heat pump and combined heat and power system for a biogas boiler according to claim 1, characterized in that: The refrigerant bypass pipeline includes a straight pipeline between the second port (12b) of the second three-way valve and the first port (14a) of the third three-way valve, and the refrigerant passage of the first heat exchanger (6) is provided in the pipeline.

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