A device for extracting and recovering latent heat of flue gas of a gas stove

Abstract

The application relates to the technical field of latent heat extraction and recovery of flue gas, in particular to a latent heat extraction and recovery device for flue gas of a gas stove, which comprises a shell, a gas inlet main pipe, a gas outlet main pipe and a plurality of heat exchange mechanisms; the heat exchange mechanism comprises a telescopic combustion assembly and a plurality of heat exchangers; the telescopic combustion assembly comprises a telescopic combustion chamber, a gas inlet branch pipe, a gas outlet branch pipe, a gas inlet branch pipe control valve, a gas outlet branch pipe control valve and an igniter; a combustion cavity is formed in the telescopic combustion chamber; the igniter is arranged in the combustion cavity; the heat exchanger is arranged outside the combustion chamber and is used for heat exchange with flue gas in the combustion cavity; one end of the gas inlet branch pipe is communicated with the gas inlet main pipe, and the other end is communicated with the combustion cavity. The telescopic function of the telescopic combustion chamber is utilized; after the flue gas enters the telescopic combustion chamber, the volume of the telescopic combustion chamber is increased, the igniter is controlled to work, carbon monoxide is ignited, air pollution is reduced, and the latent heat extraction and recovery are facilitated.

Description

Technical Field

[0001] This application relates to the field of latent heat extraction and recovery technology of flue gas, and in particular to a device for extracting and recovering latent heat from flue gas of a gas-fired furnace. Background Technology

[0002] The latent heat of flue gas in a gas-fired boiler refers to the heat released when water vapor in the flue gas condenses. It is an important component of waste heat in flue gas, and its recovery and utilization can improve thermal efficiency. The core components of flue gas in a gas-fired boiler are nitrogen, carbon dioxide, and water vapor, and may also contain small amounts of oxygen, carbon monoxide, nitrogen oxides, etc.

[0003] Currently, Chinese invention patent application with publication number CN119934833B and publication date June 24, 2025, proposes a waste heat recovery device for a roasting furnace, comprising the following structure: a converging throat is provided in the middle of the heat exchange pipe, the throat protrudes towards the outer wall of the heat exchange pipe, a first sliding plate is hinged to the top of the throat, a second sliding plate is slidably connected to the first sliding plate, a diffuser wall is hinged to the end of the second sliding plate, the diffuser wall is horizontally slidably disposed inside the heat exchange pipe, a third sliding plate is vertically slidably connected to the diffuser wall, a plurality of heat pipe finned heat exchangers are hinged to the outer wall of the heat exchange pipe, and the other side of the heat pipe finned heat exchanger connected to the outer wall of the heat exchange pipe is hinged to the third sliding plate.

[0004] By adjusting the pipe diameter of the heat exchange pipe, the cross-sectional area of ​​the flue gas flow is increased according to the flue gas temperature, which slows down and pressurizes the flue gas. A heat pipe finned heat exchanger is installed at this point to ensure that the heat exchanger always maintains full contact with the flue gas, which promotes the liquefaction of steam and releases heat to heat the external hot water, thereby realizing waste heat recovery.

[0005] Regarding the aforementioned technologies, incomplete combustion may occur during the use of natural gas. When natural gas fails to burn completely, a large amount of unburned combustible components remain in the flue gas, among which the carbon monoxide content will increase significantly, polluting the air environment and potentially posing a serious threat to human health. Summary of the Invention

[0006] This application provides a latent heat extraction and recovery device for flue gas from a gas-fired furnace. By utilizing the telescopic function of the telescopic combustion chamber, the volume of the telescopic combustion chamber increases after the flue gas enters, controlling the igniter to ignite carbon monoxide, thereby reducing air pollution and facilitating the extraction and recovery of latent heat.

[0007] This application provides a device for extracting and recovering latent heat from flue gas of a gas-fired furnace, which adopts the following technical solution:

[0008] The casing, the main inlet pipe, the main outlet pipe, and several heat exchange mechanisms;

[0009] The heat exchange mechanism includes a telescopic combustion assembly and several heat exchangers. The telescopic combustion assembly includes a telescopic combustion chamber, an inlet branch pipe, an outlet branch pipe, an inlet branch pipe control valve, an outlet branch pipe control valve, and an igniter.

[0010] The retractable combustion chamber forms a combustion cavity, the igniter is disposed inside the combustion cavity, and the heat exchanger is disposed outside the combustion chamber for exchanging heat with the flue gas inside the combustion cavity.

[0011] One end of the intake branch pipe is connected to the intake main pipe, and the other end is connected to the combustion chamber. The intake branch pipe control valve is installed on the intake branch pipe. One end of the exhaust branch pipe is connected to the combustion chamber, and the other end is connected to the exhaust main pipe. The exhaust branch pipe control valve is installed on the exhaust branch pipe to control the entry and exit of flue gas into and out of the combustion chamber.

[0012] By adopting the above technical solution, during heat exchange, the flue gas discharged from the gas furnace enters the heat exchange mechanism through the main inlet pipe. When the flue gas enters the heat exchange mechanism, the inlet branch pipe control valve controls the flue gas to enter the telescopic combustion chamber through the inlet branch pipe. After a period of time, the igniter in the telescopic combustion chamber ignites, causing the incompletely burned carbon monoxide in the flue gas to burn and release heat. As the gas pressure in the telescopic combustion chamber gradually increases, the volume of the combustion chamber gradually expands. When the combustion chamber expands to a certain volume, the outlet branch pipe control valve controls the flue gas in the telescopic combustion chamber to be discharged from the heat exchange mechanism through the outlet branch pipe, and then discharged from the recovery device through the main outlet pipe. When the inlet branch pipe control valve of one telescopic combustion chamber is closed, the flue gas discharged from the gas furnace enters another telescopic combustion chamber, and so on. During the process of the flue gas entering the telescopic combustion chamber and being ignited, the heat exchanger continuously absorbs the heat from the flue gas. Because the flue gas can be re-ignited in the combustion chamber, the amount of carbon monoxide in the flue gas discharged from the recovery device is reduced, thus reducing air pollution. Moreover, since the combustion of carbon monoxide releases heat, the recovery device can recover this heat, improving the utilization rate of the fuel gas. Because the flue gas remains in the combustion chamber throughout the heat exchange process, the heat in the flue gas is extracted by the heat exchange mechanism before being discharged from the combustion chamber, resulting in deep extraction of heat from the flue gas, improving the heat recovery rate, and saving energy.

[0013] Optionally, the telescopic combustion chamber includes a top plate, a bottom plate, several side walls, and a number of connecting plates and spring cylinder assemblies equal to the number of side walls. The top plate and the bottom plate are both connected to the tube wall of the heat exchange mechanism. One end of each side wall and the connecting plate abuts against the top plate, and the other end abuts against the bottom plate. The side walls and the connecting plates are slidably disposed between the top plate and the bottom plate. The heat exchanger is installed on the side wall. The side wall and the connecting plate are spaced apart. An installation groove is provided at the end of the side wall near the connecting plate. The connecting plate is slidably disposed in the installation groove. The free end of the spring cylinder assembly is connected to the side wall, and the spring cylinder assembly is connected to the bottom plate.

[0014] By adopting the above technical solution, the sidewalls, connecting plates, top plate, and bottom plate form a relatively sealed area to achieve temporary storage of flue gas. As flue gas enters, the pressure in the combustion chamber increases, causing the sidewalls and connecting plates to move. This causes the sidewalls to compress the spring cylinder assembly, increasing the volume of the combustion chamber. When the spring cylinder assembly reaches its limit, the inlet branch pipe closes and the outlet branch pipe opens. As the gas is discharged, the spring cylinder assembly returns to its original position, and the combustion chamber resets. During ignition, the inlet and outlet branch pipes need to be kept closed simultaneously for a period of time to allow the heat exchanger to fully exchange heat. Through continuous charging and discharging, the residence time of flue gas in the combustion chamber is increased, fully releasing latent heat and achieving latent heat extraction and recovery.

[0015] Optionally, four sidewalls are provided, with two opposing sidewalls forming a first sidewall group and the other two opposing sidewalls forming a second sidewall group. The spring cylinder group includes a first spring cylinder group and a second spring cylinder. The first spring cylinder group is connected to the corresponding first sidewall group, and the second spring cylinder group is connected to the corresponding second sidewall group. The elastic force of the first spring cylinder group is less than that of the second spring cylinder group. The telescopic combustion assembly also includes a contact sensor, which is disposed on the sliding trajectory of the sidewall belonging to the first sidewall group. The contact sensor is installed on the first spring cylinder group.

[0016] By adopting the above technical solution, when the combustion chamber expands, the side walls compress the spring cylinder assembly. The first side wall assembly corresponding to the first spring cylinder assembly moves quickly. After contacting the contact sensor, the first side wall assembly reaches its limit position, the intake manifold control valve closes the intake manifold, and the igniter ignites. When the carbon monoxide concentration is high, the flue gas combustion releases heat. When the flue gas expands in the combustion chamber, if the spring force is the same, the four side walls are essentially a rigid whole, which can easily cause damage to the side walls. Therefore, by using springs with different spring forces, the second spring cylinder can continue to compress, avoiding damage to the side walls, etc. The use of a contact sensor facilitates the control of the ignition timing.

[0017] Optionally, the telescopic combustion assembly further includes a concentration sensor disposed inside the combustion chamber.

[0018] By adopting the above technical solution, the concentration of carbon monoxide in the combustion chamber is detected by setting a concentration sensor. When the carbon monoxide concentration is high, the igniter is controlled to ignite, thereby realizing the heat release of carbon monoxide combustion and improving the latent heat utilization rate.

[0019] Optionally, the end of the intake branch pipe away from the intake manifold is located in the middle of the combustion chamber.

[0020] By adopting the above technical solution, the intake manifold extends into the middle of the combustion chamber, allowing for uniform gas distribution within the chamber. This facilitates detection by the concentration sensor, eliminating the need for multiple sensors within the combustion chamber while still achieving accurate detection. When the gas distribution is uniform, the carbon monoxide concentration tends to be consistent throughout the chamber, which not only helps achieve stable and reliable ignition but also ensures complete combustion. Uneven gas distribution may result in a higher carbon monoxide concentration at the sensor location and a lower concentration in other areas. This could lead to ignition failure due to insufficient concentration in certain areas, thus reducing the igniter's lifespan. Alternatively, a lower concentration at the sensor location and a higher concentration in other areas could cause the detected signal to be lower than the actual concentration, leading to system misjudgment and resulting in the direct emission of incompletely burned carbon monoxide into the atmosphere. This not only pollutes the environment but may also pose a threat to human health. Incomplete combustion of carbon monoxide means that its chemical energy is not fully released, and the latent heat in the flue gas cannot be effectively recovered, resulting in wasted heat energy and reduced utilization of the flue gas's latent heat. Therefore, the proper arrangement of the intake manifold plays a crucial role in achieving accurate detection, reliable ignition, complete combustion, reducing pollution, and improving energy efficiency. Furthermore, condensation is produced when the latent heat of the flue gas is released. This condensation collects on the base plate. If the upper end of the intake manifold is level with the base plate, condensation can easily enter the intake manifold, causing poor exhaust flow. Moreover, the condensation exchanges heat with the flue gas, resulting in heat damage.

[0021] Optionally, the upper end of the intake branch pipe is sealed and an exhaust hole is provided circumferentially at the end.

[0022] By adopting the above technical solution, when the flue gas flows upward from inside the inlet branch pipe, it is forced to diffuse and discharge evenly from the surrounding outlet holes, thus forming a more stable airflow field. This avoids the localized excessively high or low concentrations caused by concentrated unidirectional emission of flue gas, and allows the concentration sensor to come into contact with the mixed gas, thereby effectively improving the accuracy and reliability of the detection data.

[0023] Optionally, the igniter is electrically connected to the valve on the heat exchanger.

[0024] By adopting the above technical solution, the heat generated when the igniter ignites carbon monoxide increases. At the same time as the igniter is turned on, the valve opening on the heat exchanger increases, increasing the flow rate of the medium entering the heat exchanger, so that it can fully absorb heat and improve the heat exchange efficiency.

[0025] Optionally, the concentration sensor is installed at the upper end of the intake manifold.

[0026] By adopting the above technical solution, the concentration sensor detects more accurate data, reduces unnecessary ignition times, extends the service life of the igniter, and avoids the chain reaction problems that may be caused by data deviation, such as abnormally large valve opening of the heat exchanger and excessive medium flow. This helps maintain the system's heat exchange efficiency, reduce energy consumption, and ensure the long-term stable operation of the equipment.

[0027] Optionally, the heat exchange mechanism further includes a drain valve, which is mounted on the base plate.

[0028] By adopting the above technical solution, and when the latent heat of the flue gas is released, condensate is generated and collected on the bottom plate. It can be discharged through the drain valve, reducing heat exchange between the condensate and the flue gas and improving the heat utilization rate of the flue gas.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. This invention increases the residence time of flue gas within the combustion chamber by intermittently passing it through the retractable combustion chamber, thus fully releasing latent heat and achieving its extraction and recovery. When carbon monoxide concentration is high, the flue gas combustion releases heat, which the recovery device can reclaim, improving fuel gas utilization. Because the flue gas remains within the combustion chamber throughout the heat exchange process, the heat is extracted by the heat exchange mechanism before being discharged, resulting in deep heat extraction, improved heat recovery rate, and energy savings.

[0031] 2. This invention achieves more uniform flue gas distribution by extending the intake manifold into the middle of the combustion chamber, sealing its end, and providing an exhaust port at the top. The concentration sensor is located at the top of the intake manifold, ensuring more accurate data detection and reducing unnecessary ignition attempts.

[0032] 3. By employing a contact sensor and spring cylinders with different elastic forces, when the carbon monoxide concentration is high, the igniter ignites, the flue gas burns and releases heat, and the flue gas expands in the combustion chamber. The use of spring cylinders with different elastic forces allows part of the side wall to continue moving, thus avoiding damage to the side wall and connecting plate. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural diagram of the device in the embodiments of this application;

[0034] Figure 2 This is a schematic diagram of the internal structure of the heat exchange mechanism after being cut open in an embodiment of this application;

[0035] Figure 3 This is a partial structural diagram of the heat exchange mechanism and water storage mechanism in the embodiments of this application;

[0036] Figure 4 This is a partial structural diagram of the telescopic combustion chamber in an embodiment of this application;

[0037] Figure 5 This is an embodiment of the present application. Figure 4 A magnified view of part A in the image;

[0038] Figure 6 This is a schematic diagram showing the positions of the sidewall assembly, spring cylinder assembly, and contact sensor in an embodiment of this application.

[0039] Figure label:

[0040] 100. Main exhaust pipe;

[0041] 200. Shell;

[0042] 300. Heat exchange mechanism; 310. Telescopic combustion assembly; 311. Outlet branch pipe; 312. Outlet branch pipe control valve; 313. Inlet branch pipe control valve; 314. Inlet branch pipe; 315. Igniter; 316. Concentration sensor; 320. Heat exchanger; 330. Drain valve; 340. Telescopic combustion chamber; 341. Top plate; 342. Bottom plate; 343. Side wall; 344. Connecting plate; 345. Spring cylinder assembly; 346. First side wall assembly; 347. Second side wall assembly; 348. First spring cylinder assembly; 349. Second spring cylinder assembly; 350. Contact sensor;

[0043] 400. Water storage mechanism; 410. Water tank; 420. Water pipe;

[0044] 500. Intake manifold. Detailed Implementation

[0045] The following combination Figures 1 to 6 This application will be described in further detail.

[0046] refer to Figure 1This embodiment provides a latent heat extraction and recovery device for flue gas from a gas furnace, comprising: a shell 200, an inlet manifold 500, an outlet manifold 100, several heat exchange mechanisms 300, and a water storage mechanism 400. The shell 200 houses the several heat exchange mechanisms 300 and the water storage mechanism 400. Flue gas enters the heat exchange mechanism 300 from the inlet manifold 500, where the heat exchanger 320 absorbs the latent heat of the flue gas. When the carbon monoxide concentration is high, the flue gas is ignited, releasing heat through carbon monoxide combustion, thus reducing air pollution. The water storage mechanism 400 collects the condensate generated during heat exchange. The flue gas after heat exchange is discharged from the outlet manifold 100, achieving full extraction and recovery of latent heat.

[0047] refer to Figure 2-5 The heat exchange mechanism 300 includes a telescopic combustion assembly 310, several heat exchangers 320, and a drain valve 330. The telescopic combustion assembly 310 includes a telescopic combustion chamber 340, an inlet branch pipe 314, an outlet branch pipe 311, an inlet branch pipe control valve 313, an outlet branch pipe control valve 312, an igniter 315, a concentration sensor 316, and a contact sensor 350. A combustion chamber is formed inside the telescopic combustion chamber 340. The igniter 315 and the concentration sensor 316 are disposed inside the combustion chamber. The heat exchangers 320 are disposed outside the combustion chamber for heat exchange with the flue gas inside the combustion chamber. The contact sensor... 350 is located outside the combustion chamber and is used to control the ignition time of the igniter 315. The igniter 315 is electrically connected to the valve on the heat exchanger 340. The drain valve 330 is installed at the bottom of the telescopic combustion chamber 340. One end of the intake branch pipe 314 is connected to the intake main pipe 500, and the other end is connected to the combustion chamber. The intake branch pipe control valve 313 is installed on the intake branch pipe 314. One end of the exhaust branch pipe 311 is connected to the combustion chamber, and the other end is connected to the exhaust main pipe 100. The exhaust branch pipe control valve 312 is installed on the exhaust branch pipe 311 and is used to control the entry and exit of flue gas into and out of the combustion chamber.

[0048] refer to Figure 2-5During heat exchange, the flue gas discharged from the gas furnace enters the heat exchange mechanism 300 through the main intake pipe 500. The intake branch pipe control valve 313 controls the flue gas to enter the telescopic combustion chamber 340 through the intake branch pipe 314. After a period of time, the concentration sensor 316 detects the concentration of carbon monoxide. When the concentration reaches the preset value, the igniter 315 in the telescopic combustion chamber 340 ignites the gas. During ignition, the intake branch pipe control valve 313 and the exhaust branch pipe control valve 312 are closed for a period of time, allowing the incompletely burned carbon monoxide in the flue gas to burn and release heat. When the igniter 315 ignites the carbon monoxide, the heat generated increases. At the same time as the igniter 315 is opened, the valve opening on the heat exchanger 320 increases, increasing the flow rate of the medium input to the heat exchanger, allowing it to fully absorb heat and improve the heat exchange efficiency. When the flue gas releases heat, condensate is generated and discharged from the drain valve 330. As the gas pressure in the telescopic combustion chamber gradually increases, the volume of the combustion chamber gradually expands. When the combustion chamber expands to a certain volume, the exhaust branch control valve 312 controls the flue gas in the telescopic combustion chamber to be discharged from the heat exchange mechanism 300 through the exhaust branch pipe 311, and then discharged from the recovery device through the exhaust main pipe 100. The flue gas discharged from the gas furnace enters another telescopic combustion chamber 340, and the cycle continues.

[0049] refer to Figure 2-5 During the process of flue gas entering the retractable combustion chamber 340 and being ignited, the heat exchanger 320 continuously absorbs heat from the flue gas. Because the flue gas can be re-ignited within the combustion chamber, the amount of carbon monoxide in the flue gas discharged from the recovery device is reduced, thus reducing air pollution. Furthermore, since the combustion of carbon monoxide releases heat, the heat recovery device can recover this heat, improving the utilization rate of the fuel gas. Because the flue gas remains within the combustion chamber throughout the heat exchange process, and the heat in the flue gas is extracted by the heat exchange mechanism 300 before being discharged from the combustion chamber, the heat in the flue gas is deeply extracted, improving the heat recovery rate and saving energy.

[0050] refer to Figure 4 and 5 The intake branch pipe 314, located away from the main intake pipe 500, is positioned in the middle of the combustion chamber. The upper end of the intake branch pipe 314 is sealed, and an outlet hole 317 is circumferentially opened at its end. The concentration sensor 316 and the igniter 315 are installed at the upper end of the intake branch pipe 314. Flue gas in the intake branch pipe 314 is discharged through the outlet hole 317, resulting in a more uniform flue gas distribution and more accurate data detection by the concentration sensor 316. This avoids potential chain reactions caused by data deviations, such as abnormally large valve openings in the heat exchanger or excessively high medium flow rates. This helps maintain system heat exchange efficiency, reduces energy consumption, and ensures long-term stable operation of the equipment.

[0051] refer to Figure 3 and 4The telescopic combustion chamber 340 includes a top plate 341, a bottom plate 342, several side walls 343, a number of connecting plates 344 equal to the number of side walls, and spring cylinder assemblies 345. The top plate 341 and the bottom plate 342 are both connected to the pipe wall of the heat exchange mechanism 300. The drain valve 330 is installed on the bottom plate 342. The intake branch pipe 314 passes through the bottom plate 342 in a sealed manner. The spring cylinder assemblies 345 are connected to the bottom plate 342. Adjacent spring cylinder assemblies 345 have different spring forces. The contact sensor 350 is installed on the spring cylinder assembly 345 with the smaller spring force. The side walls 343 are connected to the springs. At the free end of the cylinder assembly 345, the heat exchanger 320 is mounted on the side wall 343. One end of the side wall 34 and the connecting plate 344 abuts against the top plate 341, and the other end abuts against the bottom plate 342. The side wall 343 and the connecting plate 344 are slidably disposed between the top plate 341 and the bottom plate 342. The side wall 343 and the connecting plate 344 are spaced apart to form a square area. The side wall 343 is provided with a mounting groove at the end near the connecting plate 344, and the connecting plate 344 is slidably disposed in the mounting groove. The air outlet branch pipe 311 is mounted on the top plate 341.

[0052] refer to Figure 6 The sidewalls 343 are provided in four configurations. Two opposing sidewalls 343 form a first sidewall group 346, and the other two opposing sidewalls 343 form a second sidewall group 347. The spring cylinder group 345 includes a first spring cylinder group 348 and a second spring cylinder group 349. The first spring cylinder group 348 is connected to the corresponding first sidewall group 346, and the second spring cylinder group 349 is connected to the corresponding second sidewall group 347. The elastic force of the first spring cylinder group 348 is less than the elastic force of the second spring cylinder group 349. The contact sensor 350 is disposed on the sliding trajectory of the sidewall 343 belonging to the first sidewall group 346, and the contact sensor 350 is mounted on the first spring cylinder group 348.

[0053] refer to Figure 3 , 46. The side wall 343, connecting plate 344, top plate 341, and bottom plate 342 form a relatively sealed area to temporarily store flue gas. As flue gas enters, the pressure in the combustion chamber increases, causing the side wall 343 and connecting plate 344 to move. This causes the side wall 343 to squeeze the spring cylinder assembly 345, increasing the volume of the combustion chamber. The first side wall assembly 346 corresponding to the first spring cylinder assembly 348 moves quickly. After contacting the contact sensor 350, the first side wall assembly 346 reaches its limit position (the free end of the first spring cylinder assembly 348 is completely inside the cylinder), and the intake branch pipe control valve 313 closes the intake branch pipe 314. When the carbon monoxide concentration is high, the igniter 315 ignites, requiring the intake branch pipe 314 and the outlet branch pipe 311 to be closed simultaneously for a period of time to allow the heat exchanger 320 to exchange heat fully. When the flue gas burns and releases heat, and the flue gas expands in the combustion chamber, if the spring forces are the same, the four side walls are essentially a rigid whole, which can easily cause damage to the side walls. Therefore, by using springs with different elasticity, the second spring cylinder assembly 349 can continue to compress, avoiding damage to the side wall 343, etc. The intake branch pipe 314 is closed, and the exhaust branch pipe 315 is opened. As the gas is discharged, the spring cylinder assembly 345 returns to its original position, and the combustion chamber resets. Through continuous charging and discharging, the residence time of the flue gas in the combustion chamber is increased, fully releasing latent heat and achieving latent heat extraction and recovery.

[0054] refer to Figure 3 The water storage mechanism 400 includes a water tank 410 and a water pipe 420. The water tank 410 is mounted on the housing 200. One end of the water pipe 420 is connected to the water tank 410. The water pipe 420 passes through the pipe wall of the heat exchange mechanism 300 in a sealed manner. The drain valve 330 is connected to the other end of the water pipe 420. The water discharged from the drain valve 330 is collected in the water tank 410 through the water pipe 420 to prevent condensate from remaining inside the heat exchange mechanism 300.

[0055] The working principle of this embodiment is as follows:

[0056] The flue gas discharged from the gas furnace enters the heat exchange mechanism 300 through the main intake pipe 500. The intake branch pipe control valve 313 controls the flue gas to pass through the intake branch pipe 314. The flue gas in the intake branch pipe 314 is discharged through the exhaust port 317, making the flue gas distribution more uniform as it enters the telescopic combustion chamber 340. As the flue gas enters, the pressure in the combustion chamber increases, causing the side wall 343 and connecting plate 344 to move. This causes the side wall 343 to compress the spring cylinder assembly 345, thus increasing the volume of the combustion chamber. The first side wall assembly 346 moves quickly and, after contacting the contact sensor 350, the intake branch pipe control valve 313 closes. The intake branch pipe 314 and the concentration sensor 316 detect the concentration of carbon monoxide. After the concentration reaches a preset value, the igniter 315 in the telescopic combustion chamber 340 ignites the gas. During ignition, the intake branch pipe control valve 313 and the outlet branch pipe control valve 312 are closed for a period of time, allowing the incompletely burned carbon monoxide in the flue gas to burn and release heat. When the igniter 315 ignites the carbon monoxide, the heat generated increases. At the same time as the igniter 315 is opened, the valve opening on the heat exchanger 320 increases, increasing the flow rate of the medium entering the heat exchanger, allowing it to fully absorb heat and improve heat exchange efficiency. When the flue gas releases heat, condensate is generated and discharged from the drain valve 330. The water discharged from the drain valve 330 is collected in the water tank 410 through the water pipe 420, preventing condensate from remaining inside the heat exchange mechanism 300. As the gas pressure inside the telescopic combustion chamber gradually increases, the volume of the combustion chamber gradually expands. When the combustion chamber expands to a certain volume, the exhaust branch control valve 312 controls the flue gas in the telescopic combustion chamber to be discharged from the heat exchange mechanism 300 through the exhaust branch pipe 311, and then discharged from the recovery device through the exhaust main pipe 100. When the intake branch control valve 313 of one telescopic combustion chamber 340 is closed, the flue gas discharged from the gas furnace enters another telescopic combustion chamber 340, and so on.

[0057] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A device for extracting and recovering latent heat from flue gas of a gas-fired furnace, characterized in that, include: The casing (200), the inlet manifold (500), the outlet manifold (100), and several heat exchange mechanisms (300); The heat exchange mechanism (300) includes a telescopic combustion assembly (310) and several heat exchangers (320). The telescopic combustion assembly (310) includes a telescopic combustion chamber (340), an intake branch pipe (314), an outlet branch pipe (311), an intake branch pipe control valve (313), an outlet branch pipe control valve (312), and an igniter (315). The telescopic combustion chamber (340) forms a combustion chamber inside, the igniter (315) is disposed inside the combustion chamber, and the heat exchanger (320) is disposed outside the telescopic combustion chamber (340) for exchanging heat with the flue gas inside the combustion chamber; One end of the intake branch pipe (314) is connected to the intake main pipe (500), and the other end is connected to the combustion chamber. The intake branch pipe control valve (313) is installed on the intake branch pipe (314). One end of the exhaust branch pipe (311) is connected to the combustion chamber, and the other end is connected to the exhaust main pipe (100). The exhaust branch pipe control valve (312) is installed on the exhaust branch pipe (311) and is used to control the entry and exit of flue gas into and out of the combustion chamber. The telescopic combustion chamber (340) includes a top plate (341), a bottom plate (342), several side walls (343), and a number of connecting plates (344) and spring cylinder assemblies (345) equal to the number of side walls. The top plate (341) and the bottom plate (342) are both connected to the tube wall of the heat exchange mechanism (300). One end of each side wall (343) and the connecting plate (344) abuts against the top plate (341), and the other end abuts against the bottom plate (342). The side wall (343) and the connecting plate (344) are connected to each other. 4) Both are slidably disposed between the top plate (341) and the bottom plate (342). The heat exchanger (320) is installed on the side wall (343). The side wall (343) and the connecting plate (344) are spaced apart. The side wall (343) has an installation groove at one end near the connecting plate (344). The connecting plate (344) is slidably disposed in the installation groove. The free end of the spring cylinder assembly (345) is connected to the side wall (343). The spring cylinder assembly (345) is connected to the bottom plate (342). The sidewalls (343) are provided in four parts. Two opposite sidewalls (343) form a first sidewall group (346), and two other opposite sidewalls (343) form a second sidewall group (347). The spring cylinder group (345) includes a first spring cylinder group (348) and a second spring cylinder group (349). The first spring cylinder group (348) is connected to the corresponding first sidewall group (346), and the second spring cylinder group (349) is connected to the corresponding second sidewall group (347). The elastic force of the first spring cylinder group (348) is less than that of the second spring cylinder group (349). The telescopic combustion assembly (310) also includes a contact sensor (350). The contact sensor (350) is set on the sliding trajectory of the sidewall (343) belonging to the first sidewall group (346). The contact sensor (350) is installed on the first spring cylinder group (348). The telescopic combustion assembly (310) also includes a carbon monoxide concentration sensor (316), which is disposed inside the combustion chamber.

2. The latent heat extraction and recovery device for gas-fired boiler flue gas according to claim 1, characterized in that: The end of the intake branch pipe (314) away from the intake main pipe (500) is located in the middle of the combustion chamber.

3. The latent heat extraction and recovery device for gas-fired boiler flue gas according to claim 2, characterized in that: The upper end of the intake branch pipe (314) is sealed and an exhaust hole (317) is opened in the circumferential direction at the end.

4. The latent heat extraction and recovery device for gas-fired boiler flue gas according to claim 3, characterized in that: The igniter (315) is electrically connected to the valve on the heat exchanger (320).

5. The latent heat extraction and recovery device for gas-fired boiler flue gas according to claim 3, characterized in that: The carbon monoxide concentration sensor (316) is installed at the upper end of the intake manifold (314).

6. The latent heat extraction and recovery device for gas-fired boiler flue gas according to claim 1, characterized in that: The heat exchange mechanism (300) also includes a drain valve (330), which is mounted on the base plate (342).

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