Gas boiler flue gas waste heat recycling system based on intermediate water circulation

Abstract

The utility model relates to the technical field of waste heat recovery and heating system, concretely is gas boiler flue gas waste heat recycling system based on intermediate water circulation, including gas boiler main part, flue gas pipeline, flue gas exhaust pipe, flue gas heat abstractor, gas lithium bromide heat pump, heating water pipe, backwater pipe and cooling side water circulation pipe network, the gas boiler main part right side is provided with air preheating mechanism, the gas boiler main part top and corresponding heating water pipe intercommunication, the gas boiler main part bottom and corresponding backwater pipe intercommunication, flue gas pipeline one side and corresponding gas boiler main part left side intercommunication, to solve gas boiler room flue gas waste heat waste, equipment corrosion, low energy efficiency etc.

Description

Technical Field

[0001] This utility model relates to the technical field of waste heat recovery and heating systems, specifically a waste heat reuse system for flue gas from a gas-fired boiler based on intermediate water circulation. Background Technology

[0002] During the operation of gas-fired boiler rooms, a large amount of heat energy is wasted with the flue gas emissions. At the same time, existing equipment suffers from problems such as severe corrosion of the air preheater, resulting in low overall boiler energy efficiency. For example, in the Dingzigu boiler room, the flue gas temperature of its 70MW gas-fired boiler is too high, reaching about 57℃-60℃. Moreover, the air preheater is severely corroded due to long-term direct heat exchange between low-temperature air and flue gas, which not only wastes energy but also affects the safe and stable operation of the boiler.

[0003] Currently, traditional heating systems have shortcomings in energy utilization, failing to fully recover waste heat from flue gas, resulting in high gas consumption and high operating costs. Furthermore, some waste heat recovery technologies also have deficiencies in terms of equipment footprint, investment costs, and water resource utilization, making it difficult to meet the modern heating industry's requirements for high efficiency, energy saving, and environmental protection. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this utility model provides a waste heat recovery and heating system for flue gas in gas-fired boiler rooms, which solves problems such as waste of flue gas waste heat, equipment corrosion, and low energy efficiency in gas-fired boiler rooms. It achieves deep recovery and utilization of flue gas waste heat, improves boiler efficiency, reduces operating costs, and enhances the overall performance of the heating system.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, this utility model provides the following technical solution: a gas boiler flue gas waste heat recovery system based on intermediate water circulation, comprising a gas boiler body, a flue gas pipe, a flue gas discharge pipe, a flue gas heat exchanger, a gas-fired lithium bromide heat pump, a hot water supply pipe, a return water pipe, and a cooling-side water circulation network. An air preheating mechanism is provided on the right side of the gas boiler body. The top of the gas boiler body is connected to the corresponding hot water supply pipe, and the bottom of the gas boiler body is connected to the corresponding return water pipe. One side of the flue gas pipe is connected to the left side of the corresponding gas boiler body, and the other side of the flue gas pipe is connected to the corresponding flue gas heat exchanger. The top of the flue gas heat exchanger is connected to the corresponding flue gas discharge pipe. The gas-fired lithium bromide heat pump is connected to the corresponding flue gas heat exchanger through the cooling-side water circulation network. The gas-fired lithium bromide heat pump is connected to the corresponding hot water supply pipe and the corresponding return water pipe through a connecting mechanism.

[0008] Furthermore, the air preheating mechanism also includes an air preheater and a blower. One side of the blower is connected to one side of the main body of the gas boiler through an air inlet pipe, and the other side of the blower is connected to the corresponding air preheater through an air inlet pipe. The air preheater is a corrosion-resistant air preheater.

[0009] Furthermore, the connection mechanism also includes a first cold water pipe and a first hot water pipe. The first hot water pipe is connected to the top area of ​​the corresponding gas-fired lithium bromide heat pump side and the hot water supply pipe, and the first cold water pipe is connected to the bottom area of ​​the corresponding gas-fired lithium bromide heat pump side and the return water pipe.

[0010] Furthermore, an improvement of this utility model is that the gas-fired lithium bromide heat pump is a direct-fired lithium bromide heat pump.

[0011] Furthermore, an improvement of this utility model is that the flue gas heat exchanger adopts a high-efficiency plate heat exchanger.

[0012] (III) Beneficial Effects

[0013] Compared with the prior art, this utility model provides a waste heat recovery system for flue gas from a gas-fired boiler based on intermediate water circulation, which has the following beneficial effects:

[0014] Highly efficient waste heat recovery and reduced gas consumption: By combining a high-efficiency plate heat exchanger (flue gas heat exchanger) with a direct-fired lithium bromide heat pump, waste heat from gas-fired boiler flue gas can be deeply recovered. The flue gas heat exchanger cools the flue gas from 57℃-60℃ to about 30℃, recovering a large amount of waste heat to heat the water on the cooling side and the boiler's fresh air. The heated water on the cooling side then enters the direct-fired lithium bromide heat pump, further enhancing the heating capacity, reducing the gas consumption required by the gas-fired boiler to achieve the same heating effect, and improving energy efficiency.

[0015] Improving boiler efficiency and ensuring safe operation: The air preheater and blower in the air preheating mechanism work together to heat the air entering the gas boiler, reduce the production of condensate, make combustion more complete, and improve boiler efficiency and safety.

[0016] Reduce corrosion risk and extend system service life: The air preheater is made of corrosion-resistant material. The system condensate is concentrated in the air preheater and discharged, which solves the problem of severe corrosion of the original equipment, reduces safety hazards, and ensures the stable operation of the boiler.

[0017] Optimize the heating system and improve heating quality: The direct-fired lithium bromide heat pump is connected to the hot water supply pipe and the return water pipe through a connection mechanism. After heating the return water, it is sent back to the hot water supply pipe. The cooling side water circulation network enables the water in the system to be recycled, ensuring the continuity of waste heat recovery and heat transfer, and enhancing the stability of the heating system.

[0018] Highly adaptable and meets environmental protection requirements: This system is suitable for gas-fired boiler rooms of different sizes, effectively reduces gas consumption and pollutant emissions, complies with environmental protection policies, helps achieve carbon peaking and carbon neutrality goals, and also achieves flue gas whitening, which is environmentally friendly.

[0019] In summary, the waste heat from the flue gas in this practical solution not only heats the return water of the main body of the gas-fired boiler, but also preheats the fresh air entering the main body of the gas-fired boiler, thus realizing the aforementioned system advantages. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to this utility model.

[0021] Figure 2 This is a schematic diagram of the first part of the waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to this utility model.

[0022] Figure 3 This is a structural schematic diagram of the main view of the waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to this utility model.

[0023] In the diagram: 1. Main body of gas boiler; 2. Flue gas duct; 3. Flue gas exhaust pipe; 4. Flue gas heat exchanger; 5. Gas lithium bromide heat pump; 6. Hot water supply pipe; 7. Return water pipe; 8. Cooling side water circulation network; 9. Air preheater; 10. Blower; 11. First cold water pipe; 12. First hot water pipe. Detailed Implementation

[0024] 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.

[0025] Please see Figure 1-3A waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation includes a gas-fired boiler body 1, a flue gas pipe 2, a flue gas discharge pipe 3, a flue gas heat exchanger 4, a gas-fired lithium bromide heat pump 5, a hot water supply pipe 6, a return water pipe 7, and a cooling-side water circulation network 8. An air preheating mechanism is provided on the right side of the gas-fired boiler body 1. The top of the gas-fired boiler body 1 is connected to the corresponding hot water supply pipe 6, and the bottom of the gas-fired boiler body 1 is connected to the corresponding return water pipe 7. One side of the flue gas pipe 2 is connected to the corresponding left side of the gas-fired boiler body 1, and the other side of the flue gas pipe 2 is connected to the corresponding flue gas heat exchanger 4. The top of the flue gas heat exchanger 4 is connected to the corresponding flue gas discharge pipe 3. The gas-fired lithium bromide heat pump 5 is connected to the corresponding flue gas heat exchanger 4 through the cooling-side water circulation network 8. The gas-fired lithium bromide heat pump 5 is connected to the corresponding hot water supply pipe 6 and the corresponding return water pipe 7 through a connecting mechanism.

[0026] When this device is in use

[0027] Start-up phase: Turn on the gas boiler body 1, blower 10, and related circulating water pumps to start the system. The gas boiler body 1 is ignited and combusted, producing high-temperature flue gas. Blower 10 sends air into air preheater 9. After being heated in air preheater 9, the air enters the gas boiler body through the air inlet duct to participate in combustion, improving combustion efficiency.

[0028] The air is preheated using the return water from the gas-fired boiler body 1 at 28°C. This, combined with the blower 10 and air preheater 9, forces the air into the gas-fired boiler body 1. The return water temperature in the gas-fired boiler body 1 drops from 28°C to 25°C. This design prevents condensation on the cold fresh air and utilizes the waste heat from the flue gas at 57°C to preheat the fresh air, thus saving energy. It also increases the temperature of the fresh air and improves the combustion efficiency of the gas-fired boiler body 1. In summary, this efficient use of waste heat from the flue gas not only heats the return water in the gas-fired boiler body 1 but also preheats the fresh air entering the boiler body 1.

[0029] Waste heat recovery stage: The high-temperature flue gas generated by the main body 1 of the gas boiler enters the high-efficiency plate heat exchanger flue gas heat extractor 4 through the flue gas pipe 2. In the flue gas heat extractor 4, the flue gas exchanges heat with the water in the cooling side water circulation network 8, and the flue gas temperature drops from about 57℃-60℃ to about 30℃. The released heat raises the temperature of the water on the cooling side from 25℃ to 39℃. The cooled flue gas is discharged through the flue gas discharge pipe 3.

[0030] Heat enhancement and heating stage: Hot water at 39°C enters the gas-fired lithium bromide heat pump 5 through the cooling side water circulation network 8. The gas-fired lithium bromide heat pump 5 uses the heat energy from gas combustion as its driving heat source and, utilizing the principle of absorption heat pump, further cools the hot water to 28°C, extracting the heat to heat the 47°C return water flowing in from the return water pipe 7. The heated return water reaches 80°C and enters the hot water supply pipe 6 through the first hot water pipe 12, providing high-temperature hot water for heating users.

[0031] Circulation phase: After heat exchange at the user end, the low-temperature water at 47°C flows back through the return water pipe 7. Part of it enters the gas lithium bromide heat pump 5 through the first cold water pipe 11 to be reheated, and the other part enters the cooling side water circulation network 8 to mix with the hot water from the flue gas heat exchanger 4 or to replenish the water loss in the system. Then it enters the flue gas heat exchanger 4 again to absorb the waste heat of the flue gas. This cycle repeats to achieve continuous waste heat recovery and heating process.

[0032] Shutdown Phase: When it is necessary to stop the system operation, first shut off the gas supply to the main gas boiler to stop combustion. Then, shut down the blower 10, circulating water pump, and other equipment in sequence. After the system stops running, maintenance can be performed on the equipment, checking the operating status of each component, cleaning dirt and impurities inside the equipment, and ensuring the safety and stability of the system's next operation.

[0033] As a preferred embodiment of the above, the air preheating mechanism further includes an air preheater 9 and a blower 10. One side of the blower 10 is connected to one side of the gas boiler body 1 through an air inlet pipe, and the other side of the blower 10 is connected to the corresponding air preheater 9 through an air inlet pipe. The air preheater 9 is a corrosion-resistant air preheater 9.

[0034] As a preferred embodiment of the above, the connection mechanism further includes a first cold water pipe 11 and a first hot water pipe 12. The first hot water pipe 12 is connected to the top area of ​​the corresponding gas-fired lithium bromide heat pump 5 and the hot water supply pipe 6. The first cold water pipe 11 is connected to the bottom area of ​​the corresponding gas-fired lithium bromide heat pump 5 and the return water pipe 7.

[0035] As a preferred embodiment of the above, the gas-fired lithium bromide heat pump 5 is a direct-fired lithium bromide heat pump.

[0036] As a preferred embodiment of the above, the flue gas heat exchanger 4 adopts a high-efficiency plate heat exchanger.

[0037] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0038] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0039] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0040] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A gas-fired boiler flue gas waste heat recovery system based on intermediate water circulation, comprising a gas-fired boiler body (1), a flue gas pipe (2), a flue gas discharge pipe (3), a flue gas heat exchanger (4), a gas-fired lithium bromide heat pump (5), a hot water supply pipe (6), a return water pipe (7), and a cooling-side water circulation network (8). An air preheating mechanism is provided on the right side of the gas-fired boiler body (1). The top of the gas-fired boiler body (1) is connected to the corresponding hot water supply pipe (6), and the bottom of the gas-fired boiler body (1) is connected to the corresponding return water pipe (6). 7) Connecting, one side of the flue gas pipe (2) is connected to the left side of the corresponding gas boiler body (1), the other side of the flue gas pipe (2) is connected to the corresponding flue gas heat exchanger (4), the top of the flue gas heat exchanger (4) is connected to the corresponding flue gas discharge pipe (3), the gas lithium bromide heat pump (5) is connected to the corresponding flue gas heat exchanger (4) through the cooling side water circulation network (8), and the gas lithium bromide heat pump (5) is connected to the corresponding hot water supply pipe (6) and the corresponding return water pipe (7) through the connecting mechanism.

2. The waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to claim 1, characterized in that, The air preheating mechanism also includes an air preheater (9) and a blower (10). One side of the blower (10) is connected to one side of the gas boiler body (1) through an air inlet pipe, and the other side of the blower (10) is connected to the corresponding air preheater (9) through an air inlet pipe. The air preheater (9) is a corrosion-resistant air preheater (9).

3. The waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to claim 2, characterized in that, The connection mechanism also includes a first cold water pipe (11) and a first hot water pipe (12). The first hot water pipe (12) is connected to the top area of ​​the corresponding gas-fired lithium bromide heat pump (5) and the hot water supply pipe (6). The first cold water pipe (11) is connected to the bottom area of ​​the corresponding gas-fired lithium bromide heat pump (5) and the return water pipe (7).

4. The waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to claim 3, characterized in that, The gas-fired lithium bromide heat pump (5) is a direct-fired lithium bromide heat pump.

5. The waste heat recovery system for gas-fired boiler flue gas based on intermediate water circulation according to claim 4, characterized in that, The flue gas heat exchanger (4) adopts a high-efficiency plate heat exchanger.

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