A combined cooling, heating, and power system and methane production system based on waste heat from a gas-fired boiler.

Abstract

This utility model discloses a combined cooling, heating, and power (CCHP) and methanation system based on waste heat from a gas-fired boiler. The system includes a gas-fired boiler unit, a Goswami cycle unit with ejectors, an air-source heat pump unit, a semi-efficiency absorption refrigeration cycle unit, and an anaerobic fermentation unit. The gas-fired boiler unit, the Goswami cycle unit with ejectors, the air-source heat pump unit, and the semi-efficiency absorption refrigeration cycle unit all provide heating; the Goswami cycle unit with ejectors provides cooling and power; and the anaerobic fermentation unit produces methanation. This utility model achieves efficient, low-carbon, and stable combined cooling, heating, and power generation through energy cascade utilization, deep waste heat recovery, multi-source dynamic coupling, and synergistic optimization of the electricity-cooling-heating-gas system.

Description

Technical Field

[0001] This utility model belongs to the field of energy comprehensive utilization and environmental protection engineering technology, specifically relating to a combined cooling, heating and power and methane production system based on waste heat from a gas-fired boiler. Background Technology

[0002] The statements herein provide only background information related to this invention and do not necessarily constitute prior art.

[0003] Gas-fired boilers are heat energy conversion devices that use natural gas, liquefied petroleum gas, or other fuels to heat water or generate steam through combustion. They are mainly used for heating, bathing, and industrial heating. Gas-fired boiler exhaust gas typically only recovers a portion of its heat through simple heat exchangers, resulting in underutilization of its high-temperature energy and low waste heat recovery efficiency. Furthermore, existing waste heat recovery systems often employ a single power generation or heating mode, failing to achieve combined cooling, heating, and power (CCHP), leading to the waste of low-grade waste heat. In addition, conventional Goswami cycles rely on mechanical pumps to drive the circulation of ammonia-water mixtures, resulting in issues such as wear and tear on moving parts, efficiency fluctuations due to load variations, and high maintenance costs. While biogas produced by anaerobic fermentation can be used as fuel, it does not synergize with the boiler exhaust gas waste heat, leading to a break in the energy utilization chain and low waste resource utilization efficiency.

[0004] In recent years, some studies have attempted to optimize energy systems. For example, replacing mechanical pumps in the Goswami cycle with ejectors utilizes high-pressure fluid to eject low-pressure working fluid, reducing mechanical losses and improving dynamic response capabilities; combining waste heat power generation with heat pump / refrigeration systems achieves combined cooling, heating, and power (CCHP). However, existing technologies still fail to address core issues: insufficient cascaded utilization of energy, with high-temperature exhaust gas, medium-temperature waste heat, and low-grade waste heat not being utilized according to their grade, resulting in high energy losses; poor system dynamic adaptability, with subsystems unable to coordinate and adjust during load fluctuations, affecting overall efficiency; and insufficient coordination between anaerobic fermentation and the main system, failing to create a closed loop between biogas production and boiler fuel demand. Utility Model Content

[0005] The purpose of this invention is to provide a combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler. Through energy cascade utilization, deep waste heat recovery, multi-source dynamic coupling, and synergistic optimization of electricity, cooling, heating, and gas, it achieves the goal of high efficiency, low carbon emissions, and stable combined cooling, heating, and power generation.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution: In a first aspect, embodiments of this utility model provide a combined cooling, heating, and power (CCHP) and methanogenic system based on waste heat from a gas-fired boiler, comprising a gas-fired boiler unit, a Goswami cycle unit with ejectors, an air-source heat pump unit, a semi-efficiency absorption refrigeration cycle unit, and an anaerobic fermentation unit; wherein the gas-fired boiler unit, the Goswami cycle unit with ejectors, the air-source heat pump unit, and the semi-efficiency absorption refrigeration cycle unit all provide heating, the Goswami cycle unit with ejectors provides cooling and power, and the anaerobic fermentation unit produces methanogens; The exhaust gas outlet of the gas boiler in the gas boiler unit is sequentially connected to the boiler of the Goswami cycle unit with an injector, the evaporator of the air source heat pump unit, the generator of the semi-efficiency absorption refrigeration cycle unit, the heat exchanger of the anaerobic fermentation unit, and the preheater of the gas boiler unit, so as to utilize the exhaust gas of the gas boiler in a cascade manner.

[0007] As a further technical solution, the Goswami circulation unit with ejector uses ammonia water as the working fluid and includes an absorber, a first heat exchanger, a boiler, a distiller, a distributor, an ejector, a first condenser, and a first evaporator connected in sequence to form a circulation loop; the outlet of the first evaporator is also connected to the ejector.

[0008] As a further technical solution, the concentrated ammonia saturated steam outlet of the distillation unit is connected to the distributor, and the weak ammonia saturated solution outlet of the distillation unit is sequentially connected to the boiler, the first heat exchanger, and the absorber.

[0009] As a further technical solution, the first outlet of the distributor is connected to the ejector, and the second outlet is connected in sequence to the superheater, turbine, refrigeration heat exchanger and absorber, and the turbine is connected to the generator.

[0010] As a further technical solution, the first condenser is connected to the user's heating terminal; the first evaporator and the refrigeration heat exchanger are both connected to the user's cooling terminal.

[0011] As a further technical solution, the air source heat pump unit includes a second evaporator, a compressor, and a second condenser connected in sequence to form a circulation loop. The second condenser is connected to the user's heating terminal through a pipe.

[0012] As a further technical solution, the semi-effect absorption refrigeration cycle unit uses lithium bromide aqueous solution as the working medium. The semi-effect absorption refrigeration cycle unit includes a low-pressure absorber, a low-pressure heat exchanger, a low-pressure generator, a high-pressure absorber, a high-pressure heat exchanger, a high-pressure generator, a third condenser, and a third evaporator connected in sequence to form a cycle. The low-pressure absorber, the high-pressure absorber, and the third condenser are all connected to the user's heating terminal.

[0013] As a further technical solution, the steam outlet of the high-pressure generator is connected to the third condenser, and the lithium bromide solution outlet of the high-pressure generator is connected in sequence to the high-pressure heat exchanger and the high-pressure absorber; the steam outlet of the low-pressure generator is connected to the high-pressure absorber, and the lithium bromide solution outlet of the low-pressure generator is connected in sequence to the low-pressure heat exchanger and the low-pressure absorber.

[0014] As a further technical solution, the anaerobic fermentation unit includes an anaerobic fermenter, which uses biomass as raw material and provides heat through a second heat exchanger. The methane outlet of the anaerobic fermenter is sequentially connected to a filter, a methane storage tank, and a syngas unit.

[0015] As a further technical solution, the gas boiler unit includes a gas boiler, the gas inlet of which is sequentially connected to a preheater, a gas end, and a methane storage tank; the gas boiler is also connected to the user's heating terminal.

[0016] The beneficial effects of the above-described embodiments of this utility model are as follows: This invention achieves combined cooling, heating, and power (CCHP) and synergistic methane production by incorporating a gas-fired boiler unit, a Goswami cycle unit with ejectors, an air-source heat pump unit, a semi-efficiency absorption refrigeration cycle unit, and an anaerobic fermentation unit. Simultaneously, the waste heat from the gas-fired boiler's exhaust gas can be utilized in stages through the Goswami cycle unit with ejectors, the air-source heat pump unit, the semi-efficiency absorption refrigeration unit, and the anaerobic fermentation unit, thereby improving the system's energy efficiency.

[0017] This invention novelly replaces mechanical pumps with ejector-enhanced Goswami circulation, improving circulation efficiency and reducing maintenance costs. Combined with multi-source waste heat cascade coupling technology, boiler exhaust gas, Goswami circulation, air source heat pump, and anaerobic fermentation are utilized in stages according to temperature and quality, constructing a closed-loop collaborative system with the boiler. At the same time, it involves double insurance: when the gas supply is insufficient, methane separated from biogas is used to supplement boiler fuel, and boiler ash is used as a fermentation carbon source, forming a "waste-energy-fertilizer" cycle. This invention preheats the gas before it enters the gas-fired boiler, which reduces losses from incomplete combustion, improves the boiler's thermal efficiency, and reduces the fuel required for heating, thus lowering fuel consumption. Furthermore, utilizing waste heat from the flue gas to preheat the gas creates an energy closed loop, achieving multi-source, cascaded utilization of waste heat.

[0018] This invention improves upon the traditional Goswami cycle (ammonia-water mixture) by introducing an adjustable injector to replace the mechanical pump. The injector's ejection effect reduces system losses and promotes improved cycle efficiency, while the cycle flow rate can be adaptively adjusted.

[0019] In this invention, the exhaust gas from a gas-fired boiler enters the evaporator II of an air-source heat pump unit. The waste heat from the exhaust gas can increase the evaporator inlet temperature, reduce the compression ratio, and improve the COP of the air-source heat pump. This can be controlled by a valve. Compared to similar gas-fired boiler systems, where exhaust gas is typically discharged directly into the atmosphere after waste heat utilization, this invention adds an exhaust gas treatment device. Through desulfurization and denitrification treatment, it reduces the emission of sulfur dioxide and nitrogen oxide pollutants, lowers carbon emissions, and promotes sustainable development. Attached Figure Description

[0020] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0021] Figure 1 This is a schematic diagram of the combined cooling, heating and power system and methane production system based on the waste heat of a gas-fired boiler, according to this utility model.

[0022] The diagram is for illustrative purposes only. Among them, 101, absorber; 102, first pump; 103, first heat exchanger; 104, boiler; 105, distiller; 106, distributor; 107, ejector; 108, superheater; 109, generator; 110, turbine; 111, refrigeration heat exchanger; 112, first evaporator; 113, first condenser; 201, second evaporator; 202, compressor; 203, second condenser; 301, low-pressure absorber; 302, second pump; 303, low-pressure heat exchanger; 304. Low-pressure generator; 305. High-pressure absorber; 306. Third pump; 307. High-pressure heat exchanger; 308. High-pressure generator; 309. Third condenser; 310. Third evaporator; 401. Second heat exchanger; 402. Anaerobic fermenter; 403. Impurity remover; 404. Biomass feedstock; 405. Methane storage tank; 406. Syngas unit; 501. Gas end; 502. Preheater; 503. Tail gas treatment device; 504. Gas boiler; 505. Fourth pump. Detailed Implementation

[0023] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] Example 1 In a typical embodiment of this utility model, such as Figure 1As shown, a combined cooling, heating, and power (CCHP) and methanogenic system based on waste heat from a gas-fired boiler (504) is provided. The system includes a gas-fired boiler unit, a Goswami cycle unit with ejectors, an air-source heat pump unit, a semi-efficiency absorption refrigeration cycle unit, and an anaerobic fermentation unit. The gas-fired boiler unit, the Goswami cycle unit with ejectors, the air-source heat pump unit, and the semi-efficiency absorption refrigeration cycle unit all provide heating; the Goswami cycle unit with ejectors provides cooling and power; and the anaerobic fermentation unit produces methanogens. The exhaust gas outlet of the gas boiler 504 of the gas boiler unit is sequentially connected to the boiler 104 of the Goswami cycle unit with an injector, the evaporator of the air source heat pump unit, the generator of the semi-efficiency absorption refrigeration cycle unit, the heat exchanger of the anaerobic fermentation unit, and the preheater 502 of the gas boiler unit, so as to utilize the exhaust gas of the gas boiler 504 in a cascade manner.

[0025] The aforementioned system, through the configuration of a gas-fired boiler unit, a Goswami cycle unit with ejectors, an air-source heat pump unit, a semi-efficiency absorption refrigeration cycle unit, and an anaerobic fermentation unit, achieves combined cooling, heating, and power supply and synergistic methane production. Simultaneously, the waste heat from the exhaust gas of the gas-fired boiler 504 can be utilized in stages through the Goswami cycle unit with ejectors, the air-source heat pump unit, the semi-efficiency absorption refrigeration unit, and the anaerobic fermentation unit, thereby improving the system's energy efficiency.

[0026] In this embodiment, the Goswami circulation unit with ejector uses ammonia water as the working fluid and includes an absorber 101, a first heat exchanger 103, a boiler 104, a distiller 105, a distributor 106, an ejector 107, a first condenser 113, and a first evaporator 112 connected in sequence to form a circulation loop; the outlet of the first evaporator 112 is also connected to the ejector 107.

[0027] Furthermore, the concentrated ammonia saturated vapor outlet of the distillation unit 105 is connected to the distributor 106, and the weak ammonia saturated solution outlet of the distillation unit 105 is sequentially connected to the boiler 104, the first heat exchanger 103, and the absorber 101.

[0028] Furthermore, the first outlet of the distributor 106 is connected to the ejector 107, and the second outlet is sequentially connected to the superheater 108, the turbine 110, the refrigeration heat exchanger 111, and the absorber 101. The turbine 110 is connected to the generator 109.

[0029] Furthermore, the first condenser 113 is connected to the user's heating terminal; the first evaporator 112 and the refrigeration heat exchanger 111 are both connected to the user's cooling terminal.

[0030] The working principle of the Goswami circulation unit with ejector is as follows: using ammonia water as the working fluid, the basic ammonia solution at the outlet of absorber 101 is pressurized by the first pump 102 via pipe 1 and enters the first heat exchanger 103. In the first heat exchanger 103, it exchanges heat with the weak ammonia solution (pipe 6) from boiler 104. After absorbing the heat, the basic ammonia solution enters boiler 104 via pipe 3. In boiler 104, the solution is heated to saturation and enters distiller 105 via pipe 4. The saturated steam (4) is divided into two parts in distiller 105, resulting in concentrated ammonia saturated steam (pipe 9) at the top and weak ammonia saturated solution (pipe 5) at the bottom. The weak ammonia solution at the bottom of the boiler enters the first heat exchanger 103 via pipe 6 to release heat, then enters valve Val I via pipe 7 to reduce the pressure to the circulation low pressure, and then returns to absorber 101 via pipe 8. Concentrated ammonia vapor enters the distributor 106 via pipe 9, where it is divided into two streams. One stream enters the superheater 108 via pipe 10 and is heated to a superheated state. It then drives the turbine 110 via pipe 11 to expand and generate electricity. The concentrated ammonia vapor discharged from the turbine 110 enters the refrigeration heat exchanger 111 via pipe 12, where it absorbs heat to achieve refrigeration. The other stream of concentrated ammonia vapor enters the ejector 107 via pipe 14, serving as the working fluid for the ejector 107. The vapor from pipe 14 mixes with some saturated vapor from pipe 19 within the ejector 107 and then enters the first condenser 113 via pipe 15. The condensed saturated solution enters the first evaporator 112 via pipe 16 after being depressurized by valve Val II, where it absorbs heat to achieve refrigeration. The saturated steam at the outlet of evaporator I is divided into pipe 18 and pipe 19. The saturated steam in pipe 18 and the concentrated ammonia vapor (pipe 13) at the outlet of refrigeration heat exchanger 111 enter the absorber 101 together. In the absorber 101, it is absorbed by the weak ammonia solution (pipe 8) from the first heat exchanger 103 and reforms the basic ammonia solution (1). The cycle is then completed.

[0031] The heat required by the boiler comes from pipe 20 (exhaust gas from gas boiler 504), and then flows to the air source heat pump system via pipe 21. The refrigeration heat exchanger 111, the first evaporator 112, and the user's cooling terminal exchange heat using water as the working fluid, with flow controlled by valves Val III and Val IV. The first condenser 113 exchanges heat with the user's heating terminal using water as the working fluid, with flow controlled by valve Val V.

[0032] In this embodiment, the air source heat pump unit includes a second evaporator 201, a compressor 202, and a second condenser 203 connected in sequence to form a circulation loop. The second condenser 203 is connected to the user's heating terminal through a pipe.

[0033] The working principle of the air source heat pump is as follows: the exhaust gas (pipeline 21) of the gas boiler 504 exchanges heat with the second evaporator 201. The heat transfer medium in the evaporator absorbs heat and evaporates into a gaseous state. After being compressed in the compressor 202, it becomes a high-temperature, high-pressure gas. The gas then flows into the second condenser 203 and condenses into a liquid state. Finally, it passes through the expansion valve Val VI and returns to the second evaporator 201. The water in pipe 56 exchanges heat in the second condenser 203 to become hot water. It is then supplied to the user's heating terminal via pipe 57, and the flow rate is controlled by valve Val II.

[0034] In this embodiment, the semi-effective absorption refrigeration cycle unit uses lithium bromide aqueous solution as the working medium. The semi-effective absorption refrigeration cycle unit includes a low-pressure absorber 301, a low-pressure heat exchanger 303, a low-pressure generator 304, a high-pressure absorber 305, a high-pressure heat exchanger 307, a high-pressure generator 308, a third condenser 309, and a third evaporator 310 connected in sequence to form a cycle. The low-pressure absorber 301, the high-pressure absorber 305, and the third condenser 309 are all connected to the user's heating terminal.

[0035] Furthermore, the steam outlet of the high-pressure generator 308 is connected to the third condenser 309, and the lithium bromide solution outlet of the high-pressure generator 308 is sequentially connected to the high-pressure heat exchanger 307 and the high-pressure absorber 305; the steam outlet of the low-pressure generator 304 is connected to the high-pressure absorber 305, and the lithium bromide solution outlet of the low-pressure generator 304 is sequentially connected to the low-pressure heat exchanger 303 and the low-pressure absorber 301.

[0036] The working principle of the semi-effect absorption refrigeration cycle unit is as follows: using Libr / H2O solution (lithium bromide aqueous solution) as the working medium, it can be driven by thermal energy at a temperature of 60~80℃.

[0037] The exhaust gas from pipe 22 is divided into two equal parts, which flow to the high-pressure generator 308 and the low-pressure generator 304 respectively, for both to absorb heat, and then flow out and merge along pipe 23 to the second heat exchanger 401.

[0038] The semi-efficiency absorption refrigeration cycle operates at three pressures: high, medium, and low. The high-pressure stage is located between the high-pressure generator 308 and the high-pressure absorber 305. First, the high-pressure generator 308 absorbs heat from the exhaust gas of the gas boiler 504, heating the LiBr / H2O solution into a gas-liquid mixture, namely water vapor and lithium bromide-rich water solution. The water vapor enters the third condenser 309 along pipe 41 and is condensed into liquid water. The liquid water is throttled to a low-pressure state through valve Val X via pipe 42, and then enters the third evaporator 310 along pipe 43 to evaporate and absorb heat, forming water vapor (44). The LiBr solution from the high-pressure generator 308 enters the high-pressure heat exchanger 307 through pipe 38 for cooling. The cooled LiBr solution is throttled to a medium pressure through valve Val IX via pipe 39, and then flows into the high-pressure absorber 305 along pipe 40. The medium-pressure lithium bromide solution absorbs water vapor (pipeline 45) from the low-pressure generator 304 in the high-pressure absorber 305 to form a lithium bromide solution. The lithium bromide solution is pressurized to high pressure by the third pump 306 along the pipeline 35, and then enters the high-pressure heat exchanger 307 through the pipeline 36 to heat the high-pressure LiBr solution. Finally, the high-pressure LiBr solution returns to the high-pressure generator 308 along the pipeline 37.

[0039] The low-pressure stage is located between the low-pressure generator 304 and the low-pressure absorber 301. The low-pressure generator 304 absorbs some of the heat from the pipe 22 to heat the Libr / H2O solution into a gas-liquid mixture. Water vapor enters the high-pressure absorber 305 along the pipe 45. The LiBr solution flowing out of the low-pressure generator 304 enters the low-pressure heat exchanger 303 along the pipe 32 for cooling. The cooled LiBr solution enters the valve Val VIII along the pipe 33 for throttling to a low-pressure state. The low-pressure lithium bromide solution enters the low-pressure absorber 301 along the pipe 34. The low-pressure lithium bromide solution absorbs water vapor (pipeline 44) from the third evaporator 310 in the low-pressure absorber 301 to form a lithium bromide solution. The lithium bromide solution is then pressurized to a medium-pressure state by the second pump 302 along pipeline 29. The medium-pressure lithium bromide solution enters the low-pressure heat exchanger 303 along pipeline 30 for heating. Finally, the medium-pressure LiBr solution returns to the low-pressure generator 304 along pipeline 31, completing the cycle.

[0040] In this embodiment, the anaerobic fermentation unit includes an anaerobic fermenter 402, which uses biomass as raw material and provides heat through a second heat exchanger 401. The methane outlet of the anaerobic fermenter 402 is sequentially connected to a filter 403, a methane storage tank 405, and a syngas unit 406.

[0041] The working principle of the anaerobic fermentation unit is as follows: The activity of the biogas-producing bacteria in the anaerobic fermenter 402 is greatly affected by temperature, and the optimal activity temperature for thermophilic bacteria is generally around 55℃. The temperature of the exhaust gas at pipe 23 of the gas boiler 504 is matched with this temperature. Water in the second heat exchanger 401 absorbs the heat from the exhaust gas and becomes hot water. The hot water in pipe 46 exchanges heat with the anaerobic fermenter 402, providing heat to the anaerobic fermenter 402 and maintaining the high activity of the thermophilic bacteria. The water after heat exchange returns to the second heat exchanger 401 through pipe 47.

[0042] Biomass (straw, animal manure, kitchen waste, etc.) is fed into the anaerobic digester 402 via pipe 50 as fermentation raw material. Through the biological degradation by anaerobic bacteria, biogas is produced. The biogas contains numerous impurities, which are then passed through a separator 403 via pipe 48 to remove impurities such as carbon dioxide and hydrogen sulfide. The separated methane is then fed into a methane storage tank 405 via pipe 49 for subsequent use. The methane in the storage tank can be reformed by steam, dry reforming, or partial oxidation to produce syngas (CO+H2). It can also be used to replenish fuel for the gas-fired boiler 504 via pipe 81, controlled by valve Val XV.

[0043] Anaerobic fermentation technology can be used to systematically process biomass waste to produce biogas. When the fuel supply at the gas-fired end is insufficient, the methane in the methane storage tank can be used to supplement the fuel for the gas-fired boiler. In addition, the ash residue from the boiler can be used as a carbon source supplement for the fermentation system, increasing the biogas yield by more than 10%.

[0044] In this embodiment, the gas boiler unit includes a gas boiler 504, the gas inlet of which is sequentially connected to a preheater 502, a gas end 501, and a methane storage tank 405; the gas boiler 504 is also connected to a user's heating terminal.

[0045] The working principle of the gas-fired boiler unit is as follows: Gas flows out from the gas end 501, enters the preheater 502 along the pipeline 51, exchanges heat with the exhaust gas in the pipeline 24, and heats the gas in the pipeline 51. The heated gas is then pressurized by the fourth pump 505 along the pipeline 52 and sent to the gas-fired boiler 504 for combustion. The gas-fired boiler 504 is connected to the user's heating terminal through pipelines 76, 77, and 78 for heat exchange. Val XIV plays a role in flow regulation.

[0046] The boiler exhaust gas flowing out of the preheater 502 enters the exhaust gas treatment device 503 through the pipeline 25 for carbon capture and storage, reducing carbon emissions. The carbon capture can be used for the production of urea and methanol.

[0047] The system provided in this embodiment can simultaneously output electrical energy, cooling energy, heating energy, and methane to meet users' heating and cooling needs. The electrical energy can be further connected to the power grid, and the methane produced by anaerobic fermentation can be further processed into syngas (CO+H2) through steam reforming, dry reforming, or partial oxidation. The system has a wide range of heating sources: a gas boiler, a first condenser, a second condenser, a low-pressure absorber, a high-pressure absorber, and a third condenser, ensuring a 24-hour hot water supply for users. Cooling is provided by a refrigeration heat exchanger and a first evaporator, meeting users' cooling needs.

[0048] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. 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 cooling, heating and power (CCHP) and methane production system based on waste heat of a gas-fired boiler, characterized in that, It includes a gas-fired boiler unit, a Goswami cycle unit with ejectors, an air-source heat pump unit, a semi-efficiency absorption refrigeration cycle unit, and an anaerobic fermentation unit; wherein, the gas-fired boiler unit, the Goswami cycle unit with ejectors, the air-source heat pump unit, and the semi-efficiency absorption refrigeration cycle unit all provide heating, the Goswami cycle unit with ejectors provides cooling and power, and the anaerobic fermentation unit produces methane; The exhaust gas outlet of the gas boiler in the gas boiler unit is sequentially connected to the boiler of the Goswami cycle unit with an injector, the evaporator of the air source heat pump unit, the generator of the semi-efficiency absorption refrigeration cycle unit, the heat exchanger of the anaerobic fermentation unit, and the preheater of the gas boiler unit, so as to utilize the exhaust gas of the gas boiler in a cascade manner.

2. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 1, characterized in that, The Goswami circulation unit with ejector uses ammonia as the working fluid and includes an absorber, a first heat exchanger, a boiler, a distiller, a distributor, an ejector, a first condenser, and a first evaporator connected in sequence to form a circulation loop; the outlet of the first evaporator is also connected to the ejector.

3. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 2, characterized in that, The concentrated ammonia saturated vapor outlet of the distillation unit is connected to the distributor, and the weak ammonia saturated solution outlet of the distillation unit is connected in sequence to the boiler, the first heat exchanger, and the absorber.

4. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 2, characterized in that, The first outlet of the distributor is connected to the ejector, and the second outlet is connected in sequence to the superheater, turbine, refrigeration heat exchanger and absorber. The turbine is connected to the generator.

5. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 4, characterized in that, The first condenser is connected to the user's heating terminal; the first evaporator and the refrigeration heat exchanger are both connected to the user's cooling terminal.

6. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 1, characterized in that, The air source heat pump unit includes a second evaporator, a compressor, and a second condenser connected in sequence to form a circulation loop. The second condenser is connected to the user's heating terminal via a pipe.

7. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 1, characterized in that, The semi-efficiency absorption refrigeration cycle unit uses lithium bromide aqueous solution as the working medium. The semi-efficiency absorption refrigeration cycle unit includes a low-pressure absorber, a low-pressure heat exchanger, a low-pressure generator, a high-pressure absorber, a high-pressure heat exchanger, a high-pressure generator, a third condenser, and a third evaporator connected in sequence to form a cycle. The low-pressure absorber, the high-pressure absorber, and the third condenser are all connected to the user's heating terminal.

8. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 7, characterized in that, The steam outlet of the high-pressure generator is connected to the third condenser, and the lithium bromide solution outlet of the high-pressure generator is connected in sequence to the high-pressure heat exchanger and the high-pressure absorber; the steam outlet of the low-pressure generator is connected to the high-pressure absorber, and the lithium bromide solution outlet of the low-pressure generator is connected in sequence to the low-pressure heat exchanger and the low-pressure absorber.

9. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 1, characterized in that, The anaerobic fermentation unit includes an anaerobic fermenter, which uses biomass as raw material and provides heat through a second heat exchanger. The methane outlet of the anaerobic fermenter is connected in sequence to a filter, a methane storage tank, and a syngas unit.

10. The combined cooling, heating, and power (CCHP) and methane production system based on waste heat from a gas-fired boiler as described in claim 9, characterized in that, The gas boiler unit includes a gas boiler, the gas inlet of which is sequentially connected to a preheater, a gas end, and a methane storage tank; the gas boiler is also connected to the user's heating terminal.

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