Device and method for utilizing flue gas waste heat of gas-fired boiler

Abstract

The invention provides a gas-fired boiler flue gas waste heat utilization device and method, and relates to the technical field of gas-fired boiler flue gas waste heat utilization, the gas-fired boiler flue gas waste heat utilization device comprises an outer cylinder, an inner cylinder, a heat exchange pipeline and a cleaning assembly, the outer cylinder is provided with a first flue gas outlet and a waste discharge port, and the inner cylinder is arranged in an inner cavity of the outer cylinder and provided with a flue gas inlet and a second flue gas outlet; the smoke inlet is suitable for being connected with a smoke exhaust pipeline of the gas-fired boiler; the heat exchange pipeline is arranged outside the inner cylinder, and the heat exchange pipeline is in contact with the inner cylinder and can generate heat transfer; the cleaning assembly comprises a driving part and a cleaning body, the driving part is in transmission connection with the cleaning body, the cleaning body and the heat exchange pipeline are both located in the cavity, the cleaning body is slidably connected with the side, away from the inner barrel, of the heat exchange pipeline, and the cleaning body comprises at least one of a cleaning brush and a high-pressure water spray head. Condensate water, dirt and the like attached to the heat exchange pipeline can be cleaned, so that the problem of low-temperature corrosion of flue gas to the wall surface of the heat exchange pipeline is solved, and the working performance of the heat exchange pipeline is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of waste heat utilization technology for flue gas from gas-fired boilers, and more particularly to a device and method for waste heat utilization of flue gas from gas-fired boilers. Background Technology

[0002] The flue gas generated during the operation of gas-fired boilers often carries a large amount of waste heat. Effectively utilizing this waste heat can improve energy efficiency, reduce energy consumption, and also reduce thermal pollution to the atmosphere. Flue gas waste heat utilization devices typically include two types: heat exchangers and waste heat boilers. Heat exchangers transfer heat from the flue gas to the water or air through separate channels using a partitioned heat exchange method. Waste heat boilers convert the heat in the flue gas into steam or hot water for heating, power generation, etc.

[0003] However, the waste heat recovery devices for gas-fired boilers in related technologies have the following problems in actual use: 1. Dust particles in flue gas are usually corrosive and easily adhere to heat exchange pipes, affecting the normal operation of waste heat recovery devices; 2. Flue gas contains nitrogen oxides and sulfur oxides, and direct emission after waste heat utilization of flue gas will pollute the environment. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] To address this, one embodiment of the present invention provides a waste heat recovery device for flue gas from a gas-fired boiler. This device can clean condensate and dirt adhering to the heat exchange pipes, thereby solving the problem of low-temperature corrosion caused by flue gas on the wall of the heat exchange pipes and ensuring the working performance of the heat exchange pipes.

[0006] Another embodiment of the present invention proposes a method for utilizing waste heat from flue gas in a gas-fired boiler.

[0007] According to an embodiment of the present invention, a waste heat recovery device for flue gas from a gas-fired boiler includes an outer cylinder, an inner cylinder, a heat exchange pipe, and a cleaning component. The outer cylinder has a first flue gas outlet and a waste discharge port. The inner cylinder is located within the cavity of the outer cylinder and has a flue gas inlet and a second flue gas outlet. The flue gas inlet is adapted to be connected to the exhaust pipe of the gas-fired boiler to allow high-temperature flue gas to enter the cavity of the inner cylinder. A cavity is defined between the outer wall surface of the inner cylinder and the inner wall surface of the outer cylinder. The first flue gas outlet, the second flue gas outlet, and the waste discharge port are all connected to the cavity. The heat exchange pipe is located outside the inner cylinder and is in contact with the inner cylinder, allowing heat transfer. The cleaning component includes a driving member and a cleaning body. The driving member is tractably connected to the cleaning body. The cleaning body and the heat exchange pipe are both located within the cavity. The cleaning body is slidably connected to the side of the heat exchange pipe opposite to the inner cylinder. The cleaning body includes at least one of a cleaning brush and a high-pressure water nozzle.

[0008] According to an embodiment of the present invention, the waste heat recovery device for gas-fired boiler flue gas comprises a double-layered waste heat recovery cylinder structure formed by the cooperation of an outer cylinder and an inner cylinder. This double-layered structure optimizes the insulation performance of the waste heat recovery cylinder structure to a certain extent, thereby improving waste heat recovery efficiency. After the high-temperature flue gas from the gas-fired boiler enters the inner cavity of the inner cylinder through the exhaust pipe, the high-temperature flue gas in the inner cylinder can exchange heat with the heat exchange pipe to heat the heat exchange medium inside the pipe, thus realizing the recovery and reuse of waste heat from the gas-fired boiler flue gas. Subsequently, the driving component in the cleaning assembly can drive the cleaning body to move relative to the heat exchange pipe, placing the cleaning body in a dry brush mode so that the cleaning brush can scrape away the heat exchange pipe from the inner cylinder. Most of the dry or loose dirt adhering to one side of the cylinder, or the cleaning unit is put into rinsing mode, so that water is sprayed continuously or intermittently from the high-pressure water nozzle. The high-pressure water is used to rinse the heat exchange pipe wall or narrow gaps that are difficult to clean, while removing the dirt adhering to the cleaning brush. This prevents the dirt from hardening on the cleaning brush and affecting the subsequent cleaning operation of the heat exchange pipe wall. Therefore, the heat exchange performance of the heat exchange pipe can be restored by cleaning the heat exchange pipe through the cleaning component. Therefore, compared with related technologies, the present invention can clean the condensate and dirt adhering to the heat exchange pipe to solve the problem of low-temperature corrosion caused by flue gas to the heat exchange pipe wall and ensure the working performance of the heat exchange pipe.

[0009] In some embodiments, the flue gas waste heat utilization device further includes a partition sleeve, which is fitted onto the inner cylinder and divides the cavity into a first chamber and a second chamber arranged sequentially from the inside to the outside. The partition sleeve is provided with a sliding groove. The first flue gas outlet, the second flue gas outlet, and the waste discharge port are all connected to the first chamber. The cleaning body and the heat exchange pipe are both located in the first chamber. The cleaning body is slidably connected to the chute.

[0010] In some embodiments, the heat exchange pipe extends spirally along the extension direction of the inner cylinder and surrounds the outer wall surface of the inner cylinder.

[0011] In some embodiments, the flow direction of the heat exchange medium in the heat exchange pipe is opposite to the flow direction of the high-temperature flue gas in the inner cylinder.

[0012] In some embodiments, the cleaning body further includes a mounting base, the driving member being tractively connected to the mounting base to drive the mounting base to move relative to the heat exchange pipe along the extension direction of the inner cylinder, the mounting base having a first receiving cavity and a mounting surface facing the side of the heat exchange pipe away from the inner cylinder, the first receiving cavity being adapted to communicate with an external water source, the cleaning brush and the high-pressure water nozzle being disposed on the mounting surface, the cleaning brush abutting against the side of the heat exchange pipe away from the inner cylinder, and the high-pressure water nozzle communicating with the first receiving cavity; There are two mounting bases, which are respectively located on both sides of the inner cylinder along its radial direction. On the projection plane orthogonal to the extension direction of the inner cylinder, the projected outer contour of the mounting base is arc-shaped.

[0013] In some embodiments, the flue gas waste heat utilization device further includes a premixed burner located outside the outer cylinder. The premixed burner has a fuel inlet, an air inlet, and a flue gas outlet. The fuel inlet is adapted to communicate with an external fuel source, the air inlet is adapted to communicate with the flue gas exhaust pipe of the gas boiler, and the flue gas outlet is connected to the flue gas inlet.

[0014] In some embodiments, the flue gas waste heat recovery device further includes a flue gas treatment component, which includes a treatment box and a treatment structure. The treatment box is located outside the outer cylinder and has a second receiving cavity with an inlet and an outlet communicating with the second receiving cavity. The inlet is connected to the first flue gas outlet. The treatment structure is located in the second receiving cavity and includes at least one of a dust removal unit, a nitrogen oxide treatment unit, a sulfur oxide treatment unit, a catalytic plate, and an activated carbon filter layer arranged in sequence to treat the heat-exchanged flue gas.

[0015] In some embodiments, the processing box includes a box body, a cover plate, and a sealing ring. The box body has an open second receiving cavity. The cover plate is detachably connected to the box body to cover the openness of the second receiving cavity. The sealing ring is sandwiched between the cover plate and the box body to seal the openness of the second receiving cavity.

[0016] In some embodiments, the processing structure includes a nitrogen oxide processing unit and a sulfur oxide processing unit. The nitrogen oxide processing unit and the sulfur oxide processing unit are arranged in a vertical direction and each includes a fixed base, an atomizing nozzle, and a surrounding plate. The fixed base is installed in the second receiving cavity. The fixed base has a third receiving cavity and is provided with a dosing port communicating with the third receiving cavity. The atomizing nozzle is located at the bottom of the fixed base and communicates with the third receiving cavity. The surrounding plate is located below the fixed base and has a liquid guiding groove with an open top. The bottom of the liquid guiding groove is provided with a liquid outlet. On a projection plane orthogonal to the vertical direction, the projected outer contour of the fixed base is located inside the projected outer contour of the liquid guiding groove.

[0017] In some embodiments, the cross-sectional area of ​​the liquid guiding groove gradually decreases from top to bottom, and the maximum cross-sectional area of ​​the liquid guiding groove is greater than or equal to the cross-sectional area of ​​the fixing seat. There are multiple atomizing nozzles, which are arranged in an array at the bottom of the mounting base.

[0018] According to an embodiment of the present invention, a method for utilizing waste heat from flue gas in a gas-fired boiler, based on the waste heat utilization device for flue gas in a gas-fired boiler described in any of the above embodiments, includes the following steps: Waste heat utilization involves introducing high-temperature flue gas from a gas-fired boiler into the inner cavity of the inner cylinder, allowing the heat exchange medium in the heat exchange pipe to exchange heat with the high-temperature flue gas, resulting in heated heat exchange medium and medium-low temperature flue gas. The heat exchange pipe is cleaned by a cleaning component that drives the cleaning body to move relative to the heat exchange pipe. The cleaning body removes condensate and dirt adhering to the heat exchange pipe.

[0019] The technical advantages of the waste heat utilization method of gas boiler flue gas according to the present invention are the same as those of the above-described waste heat utilization device of gas boiler flue gas, and will not be repeated here.

[0020] In some embodiments, after the waste heat recovery operation, the method further includes the step of: For exhaust gas treatment, the medium- and low-temperature flue gas is introduced into a treatment box, where at least one of the following components—dust removal unit, nitrogen oxide treatment unit, sulfur oxide treatment unit, catalytic plate, and activated carbon filter layer—is used to treat the flue gas, resulting in clean exhaust gas.

[0021] In some embodiments, prior to the waste heat utilization operation, the method further includes the step of: The high-temperature flue gas is premixed and heated by a premixed burner to burn off any remaining combustibles in the high-temperature flue gas and raise its temperature.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a waste heat recovery device for flue gas from a gas-fired boiler according to an embodiment of the present invention.

[0024] Figure 2 This is a cross-sectional view of a waste heat recovery device for flue gas from a gas-fired boiler according to an embodiment of the present invention.

[0025] Figure 3 yes Figure 2 A magnified schematic diagram of the structure at point A in the middle.

[0026] Figure 4 This is a schematic diagram of the mounting base in the waste heat recovery device for flue gas from a gas-fired boiler according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the structure between the treatment structure, cover plate, and sealing ring in the waste heat recovery device for flue gas from a gas-fired boiler according to an embodiment of the present invention.

[0028] Figure 6 This is a schematic flowchart of a method for utilizing waste heat from flue gas in a gas-fired boiler according to an embodiment of the present invention.

[0029] Figure label: 1. Outer casing; 11. First flue gas outlet; 12. Waste discharge port; 2. Inner cylinder; 21. Flue gas inlet; 22. Second flue gas outlet; 23. Cavity; 231. First chamber; 232. Second chamber; 3. Heat exchange pipes; 4. Cleaning components; 41. Drive unit; 42. Cleaning body; 421. Cleaning brush; 422. High-pressure water nozzle; 423. Mounting base; 4231. First receiving cavity; 4232. Mounting surface; 5. Spacer sleeve; 6. Premixed burner; 61. Fuel inlet; 62. Air inlet; 63. Flue gas outlet; 7. Flue gas treatment assembly; 71. Treatment box; 711. Second receiving cavity; 712. Smoke inlet; 713. Exhaust port; 714. Box body; 715. Cover plate; 716. Sealing ring; 72. Treatment structure; 721. Dust removal unit; 722. Nitrogen oxide treatment unit; 7221. Fixing base; 7222. Atomizing nozzle; 7223. Enclosure plate; 7224. Third receiving cavity; 7225. Chemical dosing port; 7226. Liquid guide tank; 7227. Liquid outlet; 723. Sulfur oxide treatment unit; 724. Catalytic plate; 725. Activated carbon filter layer; 73. Flow equalization plate. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] like Figure 1 and Figure 2 As shown in the figure, an embodiment of the present invention provides a waste heat recovery device for flue gas from a gas-fired boiler, comprising an outer cylinder 1, an inner cylinder 2, a heat exchange pipe 3, and a cleaning component 4. The outer cylinder 1 is provided with a first flue gas outlet 11 and a waste discharge port 12. The inner cylinder 2 is located within the inner cavity of the outer cylinder 1 and has a flue gas inlet 21 and a second flue gas outlet 22. The flue gas inlet 21 is adapted to be connected to the exhaust pipe of the gas-fired boiler to allow high-temperature flue gas to enter the inner cavity of the inner cylinder 2. A cavity 23 is defined between the outer wall surface of the inner cylinder 2 and the inner wall surface of the outer cylinder 1. The first flue gas outlet 11, the second flue gas outlet 22, and the waste discharge port 12 are all connected to the cavity 23. The heat exchange pipe 3 is located within the inner cylinder 2. Externally, the heat exchange pipe 3 is in contact with the inner cylinder 2 and heat transfer can occur; the cleaning component 4 includes a driving member 41 and a cleaning body 42, the driving member 41 and the cleaning body 42 are tractably connected, the cleaning body 42 and the heat exchange pipe 3 are both located in the cavity 23, the cleaning body 42 and the side of the heat exchange pipe 3 away from the inner cylinder 2 are slidably connected, the cleaning body 42 includes at least one of a cleaning brush 421 and a high-pressure water nozzle 422, in other words, the cleaning body may include a cleaning brush and a high-pressure water nozzle; or, the cleaning body may include a cleaning brush; or, the cleaning body may include a high-pressure water nozzle.

[0032] According to an embodiment of the present invention, the waste heat recovery device for gas-fired boiler flue gas comprises an outer cylinder 1 and an inner cylinder 2 forming a double-layered waste heat recovery cylinder structure. This double-layered structure optimizes the insulation performance of the waste heat recovery cylinder structure, thereby improving waste heat recovery efficiency. After the high-temperature flue gas from the gas-fired boiler enters the inner cavity of the inner cylinder 2 through the exhaust pipe from the flue gas inlet 21, the high-temperature flue gas in the inner cylinder 2 can exchange heat with the heat exchange pipe 3 to heat the heat exchange medium within the heat exchange pipe 3, thus realizing the recovery and reuse of waste heat from the gas-fired boiler flue gas. Subsequently, the driving component 41 in the cleaning assembly 4 can drive the cleaning body 42 to move relative to the heat exchange pipe 3, causing the cleaning body 42 to be in a dry brush mode, where the cleaning brush 421 scrapes away any debris from the heat exchange pipe 3 away from the inner cylinder. Most of the dry or loose dirt attached to one side of the cylinder 2, or, by putting the cleaning body 42 into rinsing mode, continuously or intermittently spraying water from the high-pressure water nozzle 422, uses high-pressure water to rinse the wall of the heat exchange pipe 3 or narrow gaps that are difficult to clean, while removing the dirt attached to the cleaning brush 421, preventing the dirt from hardening on the cleaning brush 421 and affecting the subsequent cleaning operation of the wall of the heat exchange pipe 3. Therefore, the heat exchange performance of the heat exchange pipe 3 can be restored by cleaning the heat exchange pipe 3 through the cleaning component 4. Thus, compared with related technologies, the present invention can clean the condensate and dirt attached to the heat exchange pipe 3, so as to solve the problem of low-temperature corrosion caused by flue gas to the wall of the heat exchange pipe 3 and ensure the working performance of the heat exchange pipe 3.

[0033] Specifically, the outer and inner cylinders can be arranged coaxially and both extend vertically. The first flue gas outlet can be located at the top of the outer cylinder. The waste discharge port can be located at the bottom of the outer cylinder. The second flue gas outlet can be located at the top of the inner cylinder. The cavity can extend vertically. The drive component can be installed outside the outer cylinder. The drive component is not limited to a drive motor; it can drive the cleaning body to move through a transmission mechanism. The transmission mechanism may include, for example, the bevel gear set, threaded rod, and slider shown in the figure. The transmission mechanism can adopt existing technology in the field, which will not be elaborated here. The heat exchange pipes can be connected to an external cold source to introduce the heat exchange medium. The heat exchange pipes can also be connected to an external heat source so that the heated heat exchange medium can be supplied with heat after heat exchange. The external cold source is not limited to the cold water pipes of the HVAC building and / or the cold water pipes of the gas boiler, while the external heat source is not limited to the hot water supply pipes of the HVAC building and / or the preheating pipes of the gas boiler.

[0034] like Figure 2 As shown, in some embodiments, the flue gas waste heat utilization device further includes a spacer 5, which is fitted on the inner cylinder 2 and divides the cavity 23 into a first chamber 231 and a second chamber 232 arranged sequentially from the inside to the outside. That is, the first chamber is closer to the inner cylinder than the second chamber. The spacer 5 is provided with a sliding groove (not shown in the figure).

[0035] The first flue gas outlet 11, the second flue gas outlet 22, and the waste outlet 12 are all connected to the first chamber 231. The cleaning body 42 and the heat exchange pipe 3 are both located in the first chamber 231. The cleaning body 42 is slidably connected to the slide. At least a portion of the aforementioned transmission mechanism is located in the second chamber.

[0036] Understandably, using a spacer can, to some extent, insulate the inner cylinder, reduce the loss of residual heat from flue gas, and also separate the inner cylinder from the aforementioned transmission mechanism to reduce the impact of condensate and dirt on the transmission mechanism, thus ensuring the working performance of the cleaning components.

[0037] Specifically, the spacer and the groove thereon can both extend in the vertical direction. Both the first chamber and the second chamber can extend in the vertical direction.

[0038] like Figure 2 As shown, in some embodiments, the heat exchange pipe 3 extends spirally along the extension direction of the inner cylinder 2 and wraps around the outer wall of the inner cylinder 2. In other words, a spiral structure of heat exchange pipe is coiled around the outside of the inner cylinder to increase the contact area between the heat exchange pipe and the inner cylinder, ensuring the heat exchange effect of both and improving the recovery rate of waste heat from the high-temperature flue gas in the inner cylinder. The heat exchange pipe is not limited to alloy pipes; for example, stainless steel pipes may be used.

[0039] like Figure 2 As shown, in some embodiments, the flow direction of the heat exchange medium in the heat exchange pipe 3 is opposite to the flow direction of the high-temperature flue gas in the inner cylinder 2, so as to further improve the heat absorption performance of the heat exchange medium in the heat exchange pipe on the waste heat of the high-temperature flue gas in the inner cylinder and extend the heat exchange time between the two.

[0040] like Figures 2 to 4 As shown, in some embodiments, the cleaning body 42 further includes a mounting base 423. The driving member 41 is connected to the mounting base 423 to drive the mounting base 423 to move relative to the heat exchange pipe 3 along the extension direction of the inner cylinder 2. The mounting base 423 has a first receiving cavity 4231 and a mounting surface 4232 facing the side of the heat exchange pipe 3 away from the inner cylinder 2. The first receiving cavity 4231 is adapted to communicate with an external water source. The cleaning brush 421 and the high-pressure water nozzle 422 are both provided on the mounting surface 4232. The cleaning brush 421 abuts against the side of the heat exchange pipe 3 away from the inner cylinder 2, and the high-pressure water nozzle 422 communicates with the first receiving cavity 4231.

[0041] There are two mounting bases 423, which are respectively located on both sides of the inner cylinder 2 along its radial direction. On the projection plane orthogonal to the extension direction of the inner cylinder 2, the projected outer contour of the mounting base 423 is arc-shaped.

[0042] Understandably, designing the mounting base as an arc-shaped structure allows the cleaning brush and high-pressure water nozzle to cover the entire heat exchange pipe's outer edge away from the inner cylinder, i.e., the outer ring of the heat exchange pipe, through two mounting bases. At the same time, the high-pressure water nozzle can perform high-pressure flushing on the narrow gaps of the spirally coiled heat exchange pipe, further optimizing the cleaning effect of the cleaning unit on the heat exchange pipe.

[0043] Specifically, there are multiple bristle clusters and high-pressure water nozzles of the cleaning brush, which are arranged in an array on the mounting surface. Any bristle cluster and any high-pressure water nozzle are spaced apart and alternately arranged. In other words, the high-pressure water nozzle is located in the area between any two adjacent bristle clusters to avoid the bristle clusters clogging the high-pressure water nozzle.

[0044] like Figure 1 As shown, in some embodiments, the flue gas waste heat utilization device further includes a premixed burner 6, which is located outside the outer cylinder 1. The premixed burner 6 has a fuel inlet 61, an air inlet 62, and a flue gas outlet 63. The fuel inlet 61 is adapted to be connected to an external fuel source, the air inlet 62 is adapted to be connected to the flue gas exhaust pipe of the gas boiler, and the flue gas outlet 63 is connected to the flue gas inlet 21.

[0045] It is understandable that during the start-up of a gas-fired boiler, load fluctuations, or when combustible components (such as CO and VOCs) are present in the flue gas... s When the concentration is momentarily high, the premixed burner can be activated to premix and burn the supplementary fuel (such as natural gas) with the high-temperature flue gas from the gas boiler. This process completely incinerates (oxidizes) the residual combustibles in the flue gas (to CO2 and H2O), achieving harmless treatment. At the same time, it increases the flue gas temperature, which is beneficial for subsequent waste heat utilization.

[0046] Specifically, the specific structure and working principle of the premixed burner can adopt the existing technology in this field. The present invention mainly utilizes the concept of "supplementary combustion" to further optimize the overall performance of the waste heat utilization device for flue gas of the gas boiler.

[0047] like Figures 2 to 5 As shown, in some embodiments, the flue gas waste heat utilization device further includes a flue gas treatment component 7. The flue gas treatment component 7 includes a treatment box 71 and a treatment structure 72. The treatment box 71 is located outside the outer cylinder 1. The treatment box 71 has a second receiving cavity 711 and is provided with a flue gas inlet 712 and an exhaust port 713 communicating with the second receiving cavity 711. The flue gas inlet 712 is connected to the first flue gas outlet 11. The treatment structure 72 is located in the second receiving cavity 711. The treatment structure 72 includes at least one of the following arranged in sequence: a dust removal unit 721, a nitrogen oxide treatment unit 722, a sulfur oxide treatment unit 723, a catalytic plate 724, and an activated carbon filter layer 725, to treat the flue gas after heat exchange.

[0048] Understandably, the flue gas treatment components can treat the medium- and low-temperature flue gas after waste heat recovery to improve the emission quality. The dust removal unit can use fiber dust filter bags, which can remove unburned carbon particles and prevent carbon buildup. The nitrogen oxide treatment unit can wash the flue gas with ammonia and urea to convert NOx into harmless N2 and H2O, thus treating the nitrogen oxides in the flue gas. The sulfur oxide treatment unit can wash the flue gas with limestone slurry to react with SO2 to produce gypsum, thus treating the sulfur oxides in the flue gas. The platinum and palladium catalysts in the catalytic plate can remove CO and VOCs. s It is oxidized into CO2 and H2O; the activated carbon filter layer can adsorb particulate matter, ash and impurities in the flue gas.

[0049] Specifically, both the treatment chamber and the second receiving cavity can extend vertically. The flue gas inlet can be located at the top of the treatment chamber. The exhaust outlet can be located at the bottom of the treatment chamber. The treatment structure may include, from top to bottom, a dust removal unit, a nitrogen oxide treatment unit, a sulfur oxide treatment unit, a catalytic plate, and an activated carbon filter layer.

[0050] Furthermore, the flue gas treatment assembly 7 also includes a flow equalization plate 73, which is disposed in the second receiving cavity 711 and located above the treatment structure 72, so that the flue gas entering through the flue gas inlet is evenly distributed by the flow equalization plate, thereby improving the subsequent treatment effect of the flue gas by the treatment structure.

[0051] like Figures 2 to 5 As shown, in some embodiments, the processing box 71 includes a box body 714, a cover plate 715, and a sealing ring 716. The box body 714 has an open second receiving cavity 711. The cover plate 715 is detachably connected to the box body 714 to cover the opening of the second receiving cavity 711. The sealing ring 716 is sandwiched between the cover plate 715 and the box body 714 to seal the opening of the second receiving cavity 711.

[0052] Understandably, designing the treatment box to include a box body and a cover facilitates the disassembly and maintenance of the treatment structure within the second containment chamber, thereby reducing the maintenance costs of the flue gas treatment components.

[0053] For example, as shown in the figure, the opening of the second receiving cavity can be opened on the side of the box body away from the waste heat utilization cylinder structure, so as to facilitate the disassembly and maintenance of the cover plate.

[0054] like Figures 2 to 5As shown, in some embodiments, the processing structure 72 includes a nitrogen oxide processing unit 722 and a sulfur oxide processing unit 723. The nitrogen oxide processing unit 722 and the sulfur oxide processing unit 723 are arranged vertically and each includes a mounting base 7221, an atomizing nozzle 7222, and a surrounding plate 7223. The mounting base 7221 is installed in the second receiving cavity 711. The mounting base 7221 has a third receiving cavity 7224 and is provided with a dosing port 7225 communicating with the third receiving cavity 7224. Atomization... The nozzle 7222 is located at the bottom of the fixed base 7221 and communicates with the third receiving cavity 7224; the surrounding plate 7223 is located below the fixed base 7221 and has a liquid guiding groove 7226 with an open top. The bottom of the liquid guiding groove 7226 is provided with a liquid outlet 7227. On the projection plane orthogonal to the vertical direction, the outer projection contour of the fixed base 7221 is located inside the outer projection contour of the liquid guiding groove 7226, so that the liquid sprayed by the atomizing nozzle can fall completely into the liquid guiding groove, preventing waste liquid from contaminating the treatment structure.

[0055] It is understandable that ammonia, urea, or limestone slurry can be added to the second containment chamber through the dosing port and sprayed out through the atomizing nozzle, so that the sprayed ammonia or urea reacts with the nitrogen oxides in the flue gas flowing through the nitrogen oxide treatment unit, or the sprayed limestone slurry reacts with the sulfur oxides in the flue gas flowing through the sulfur oxide treatment unit, and the treated waste liquid can be discharged from the outlet of the liquid guide tank.

[0056] like Figures 2 to 5 As shown, in some embodiments, the cross-sectional area of ​​the liquid guiding groove 7226 gradually decreases from top to bottom, and the maximum cross-sectional area of ​​the liquid guiding groove 7226 is greater than or equal to the cross-sectional area of ​​the fixed base 7221. The aforementioned structure is beneficial for the waste liquid to automatically collect to the outlet for discharge under the action of gravity.

[0057] Multiple atomizing nozzles 7222 are arranged in an array at the bottom of the mounting base 7221 so that the ammonia water, urea or limestone slurry sprayed by the atomizing nozzles can come into uniform contact with the flue gas, thereby improving the treatment effect on nitrogen oxides or sulfur oxides in the flue gas.

[0058] like Figure 6 As shown, an embodiment of the present invention provides a method for utilizing waste heat from flue gas in a gas-fired boiler. Based on any of the above embodiments of the gas-fired boiler flue gas waste heat utilization device, the method includes the following steps: Step S1, waste heat utilization, the high temperature flue gas of the gas boiler is introduced into the inner cavity of the inner cylinder 2, so that the heat exchange medium in the heat exchange pipe 3 exchanges heat with the high temperature flue gas, and the heated heat exchange medium and medium-low temperature flue gas are obtained. Step S2, cleaning of heat exchange pipe 3: the cleaning body 42 is moved relative to heat exchange pipe 3 by the driving component 41 of the cleaning component 4, and the cleaning body 42 cleans the condensate and dirt attached to the heat exchange pipe 3.

[0059] The technical advantages of the waste heat utilization method of gas boiler flue gas according to the present invention are the same as those of the above-described waste heat utilization device of gas boiler flue gas, and will not be repeated here.

[0060] like Figure 6 As shown, in some embodiments, after step S1, the following step is further included: Step S2', exhaust gas treatment: medium and low temperature flue gas is introduced into treatment box 71, and at least one of the following in treatment box 71—dust removal unit 721, nitrogen oxide treatment unit 722, sulfur oxide treatment unit 723, catalytic plate 724, and activated carbon filter layer 725—treats the medium and low temperature flue gas to obtain clean exhaust gas.

[0061] like Figure 6 As shown, in some embodiments, the step S1 is preceded by the following step: Step S0, supplementary combustion and heating: the premixed burner 6 premixes and burns the high-temperature flue gas and fuel to burn the residual combustibles in the high-temperature flue gas and raise the temperature of the high-temperature flue gas.

[0062] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0066] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A waste heat recovery device for flue gas from a gas-fired boiler, characterized in that, include: The outer cylinder and the inner cylinder are provided. The outer cylinder is provided with a first flue gas outlet and a waste discharge port. The inner cylinder is located in the inner cavity of the outer cylinder and has a flue gas inlet and a second flue gas outlet. The flue gas inlet is adapted to be connected to the flue gas pipe of the gas boiler so that high-temperature flue gas enters the inner cavity of the inner cylinder. A cavity is defined between the outer wall surface of the inner cylinder and the inner wall surface of the outer cylinder. The first flue gas outlet, the second flue gas outlet and the waste discharge port are all connected to the cavity. A heat exchange pipe is located outside the inner cylinder, and the heat exchange pipe is in contact with the inner cylinder and can transfer heat. A cleaning assembly includes a drive component and a cleaning body. The drive component is tractably connected to the cleaning body. The cleaning body and the heat exchange pipe are both located in the cavity. The cleaning body and the heat exchange pipe are slidably connected to the side opposite to the inner cylinder. The cleaning body includes at least one of a cleaning brush and a high-pressure water nozzle.

2. The waste heat recovery device for gas-fired boiler flue gas according to claim 1, characterized in that, The heat exchange pipe extends spirally along the extension direction of the inner cylinder and surrounds the outer wall surface of the inner cylinder; And / or, the flow direction of the heat exchange medium in the heat exchange pipe is opposite to the flow direction of the high-temperature flue gas in the inner cylinder.

3. The waste heat recovery device for gas-fired boiler flue gas according to claim 2, characterized in that, The cleaning body also includes a mounting base. The driving component is throttlely connected to the mounting base to drive the mounting base to move relative to the heat exchange pipe along the extension direction of the inner cylinder. The mounting base has a first receiving cavity and a mounting surface facing the heat exchange pipe away from the inner cylinder. The first receiving cavity is adapted to communicate with an external water source. The cleaning brush and the high-pressure water nozzle are both disposed on the mounting surface. The cleaning brush abuts against the side of the heat exchange pipe away from the inner cylinder. The high-pressure water nozzle communicates with the first receiving cavity. There are two mounting bases, which are respectively located on both sides of the inner cylinder along its radial direction. On the projection plane orthogonal to the extension direction of the inner cylinder, the projected outer contour of the mounting base is arc-shaped.

4. The waste heat recovery device for gas-fired boiler flue gas according to claim 1, characterized in that, It also includes a premixed burner, which is located outside the outer cylinder. The premixed burner has a fuel inlet, an air inlet, and a flue gas outlet. The fuel inlet is adapted to be connected to an external fuel source, the air inlet is adapted to be connected to the flue gas duct of the gas boiler, and the flue gas outlet is connected to the flue gas inlet.

5. The waste heat recovery device for gas-fired boiler flue gas according to any one of claims 1-4, characterized in that, It also includes a flue gas treatment component, the flue gas treatment component comprising: The processing box is located outside the outer cylinder. The processing box has a second receiving cavity and is provided with a smoke inlet and an exhaust outlet communicating with the second receiving cavity. The smoke inlet is connected to the first flue gas outlet. The processing structure is disposed in the second receiving cavity, and the processing structure includes at least one of the following arranged in sequence: a dust removal unit, a nitrogen oxide treatment unit, a sulfur oxide treatment unit, a catalytic plate, and an activated carbon filter layer, for treating the flue gas after heat exchange.

6. The waste heat recovery device for gas-fired boiler flue gas according to claim 5, characterized in that, The processing structure includes the nitrogen oxide processing unit and the sulfur oxide processing unit, wherein the nitrogen oxide processing unit and the sulfur oxide processing unit are arranged in a vertical direction and each includes: The device includes a fixed base and an atomizing nozzle. The fixed base is installed in the second receiving cavity. The fixed base has a third receiving cavity and is provided with a dosing port that communicates with the third receiving cavity. The atomizing nozzle is located at the bottom of the fixed base and communicates with the third receiving cavity. A surrounding plate is provided below the fixed base and has a liquid guiding channel with an open top. The bottom of the liquid guiding channel is provided with a liquid outlet. On a projection plane orthogonal to the vertical direction, the projected outer contour of the fixed base is located inside the projected outer contour of the liquid guiding channel.

7. The waste heat recovery device for gas-fired boiler flue gas according to claim 6, characterized in that, The cross-sectional area of ​​the liquid guiding groove gradually decreases from top to bottom, and the maximum cross-sectional area of ​​the liquid guiding groove is greater than or equal to the cross-sectional area of ​​the fixed base. The atomizing nozzles are multiple and arranged in an array at the bottom of the mounting base.

8. A method for utilizing waste heat from flue gas in a gas-fired boiler, based on the waste heat utilization device for flue gas in a gas-fired boiler as described in any one of claims 1-7, characterized in that, The method for utilizing waste heat from flue gas includes the following steps: Waste heat utilization involves introducing high-temperature flue gas from a gas-fired boiler into the inner cavity of the inner cylinder, allowing the heat exchange medium in the heat exchange pipe to exchange heat with the high-temperature flue gas, resulting in heated heat exchange medium and medium-low temperature flue gas. The heat exchange pipe is cleaned by a cleaning component that drives the cleaning body to move relative to the heat exchange pipe. The cleaning body removes condensate and dirt adhering to the heat exchange pipe.

9. The method for utilizing waste heat from flue gas in a gas-fired boiler according to claim 8, characterized in that, Following the waste heat utilization operation, the method further includes the step of: For exhaust gas treatment, the medium- and low-temperature flue gas is introduced into a treatment box, where at least one of the following components—dust removal unit, nitrogen oxide treatment unit, sulfur oxide treatment unit, catalytic plate, and activated carbon filter layer—is used to treat the flue gas, resulting in clean exhaust gas.

10. The method for utilizing waste heat from flue gas in a gas-fired boiler according to claim 8 or 9, characterized in that, Prior to the waste heat utilization operation, the method further includes the following steps: The high-temperature flue gas is premixed and heated by a premixed burner to burn off any remaining combustibles in the high-temperature flue gas and raise its temperature.

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