Combustion device for internal and external combined recovery of flue gas waste heat

Abstract

The invention discloses a combustion device for internal and external combined recovery of flue gas waste heat in the technical field of combustion, the combustion device comprises a combustor and a flue gas pipe arranged on the combustor, an internal waste heat recovery assembly is arranged in the combustor, and an external waste heat recovery assembly is arranged on the flue gas pipe; the external waste heat recovery assembly comprises a first heat exchanger; the first heat exchanger comprises a spraying chamber, a first heat exchange chamber and a second heat exchange chamber; the internal waste heat recovery assembly and the external waste heat recovery assembly are used for carrying out deep waste heat recovery on the flue gas, the efficiency is extremely high, the flue gas heat is fully recovered in a combined mode that high-temperature radiant heat of the flue gas is internally recovered to enhance gas disturbance and sensible heat of the flue gas is externally recovered, the exhaust gas temperature can be reduced to be close to a dew point, and the heat efficiency of the system is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of combustion, and more specifically to a combustion device that combines internal and external methods to recover waste heat from flue gas. Background Technology

[0002] Energy shortage and environmental pollution are two major challenges facing the world today. The flue gas emitted by industrial furnaces, boilers and other thermal equipment carries a large amount of medium and low temperature waste heat. If it is directly discharged into the atmosphere, it will cause huge energy waste. The thermal efficiency of the entire system can be improved by the flue gas waste heat utilization technology, so that the reactants can obtain physical sensible heat higher than their own chemical calorific value (lower heating value) before entering the combustion zone, thereby significantly improving the combustion temperature limit and combustion efficiency, while effectively suppressing the formation of thermal NOx.

[0003] Existing flue gas waste heat recovery technologies, such as economizers and air preheaters, typically only preheat the combustion air or feedwater outside the system, resulting in limited heat recovery and a narrow preheating zone, making it difficult to achieve truly efficient combustion. While some flue gas recirculation technologies can bring back some flue gas heat, they dilute the concentration of reactants, potentially affecting combustion stability. Furthermore, the radiant heat in the highest temperature zone of the combustion chamber is usually not directly utilized, and the loss of this high-quality heat energy is a bottleneck restricting further improvements in thermal efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a combustion device that combines internal and external recovery of waste heat from flue gas, which solves the problems existing in the current flue gas preheating and recovery system.

[0005] The present invention achieves the above objectives through the following technical solution: a combustion device for combined internal and external recovery of flue gas waste heat, comprising: a burner and a flue gas pipe disposed on the burner, wherein the burner is provided with an internal waste heat recovery component and the flue gas pipe is provided with an external waste heat recovery component; The external waste heat recovery assembly includes a first heat exchanger; The first heat exchanger includes a spray chamber, a first heat exchange chamber, and a second heat exchange chamber. The spray chamber is used to absorb the heat of the flue gas discharged from the flue gas pipe and remove impurities by spraying water. The first heat exchange chamber is used to absorb heat from the flue gas discharged from the spray chamber again by circulating water. The second heat exchange chamber is used to absorb the heat of the spray water after the first heat exchange chamber has been used by circulating water.

[0006] Preferably, the first heat exchanger includes a shell and a partition disposed inside the shell. The partition is used to divide the inner cavity of the shell into a spray chamber, a first heat exchange chamber and a second heat exchange chamber. The spray chamber is provided with a spray assembly. The first heat exchange chamber and the second heat exchange chamber are provided with heat exchange pipes that communicate with each other. The spray chamber is respectively connected to the first heat exchange chamber and the second heat exchange chamber.

[0007] Preferably, the spray chamber and the first heat exchange chamber are distributed sequentially along the flue gas flow direction, and both the spray chamber and the first heat exchange chamber are located above the second heat exchange chamber.

[0008] Preferably, the partition is provided with a connecting hole for connecting the spray chamber and the first heat exchange chamber, and baffles are alternately provided on the upper and lower inner walls of the connecting hole.

[0009] Preferably, the bottom height of the inner cavity of the connecting hole gradually increases along the flue gas flow direction, and a drain port is provided on the lower baffle.

[0010] Preferably, the partition plate is provided with an opening for communicating between the spray chamber and the second heat exchange chamber, and the spray chamber is provided with a blocking element for covering the opening.

[0011] Preferably, the spray chamber is provided with an air inlet for communicating with the flue gas pipe, a screw sleeve is provided in the air inlet, a screw rod is provided in the screw sleeve, a baffle plate is provided in the spray chamber for blocking the air inlet, the screw rod passes through the baffle plate and is connected to the turntable, both the baffle plate and the turntable are provided with through holes, and a magnetic component for adsorbing the turntable is provided on the baffle plate.

[0012] Preferably, the external waste heat recovery assembly further includes a second heat exchanger, a purification device, and a fan. The second heat exchanger is connected to the burner through a gas guide pipe. The fan is used to introduce air into the second heat exchanger to absorb the heat of the flue gas discharged from the first heat exchanger. The purification device is used to purify the flue gas discharged from the second heat exchanger.

[0013] Preferably, the internal waste heat recovery assembly includes a front arch, a middle arch, and a rear arch; The front arch, middle arch, and rear arch divide the burner's inner cavity into three layers from top to bottom.

[0014] The beneficial effects of this invention are as follows: 1. The system achieves deep waste heat recovery from flue gas through internal and external waste heat recovery components, which is highly efficient. By combining the high-temperature radiant heat recovery of flue gas to enhance gas disturbance and the sensible heat recovery of flue gas from the outside, the system achieves full recovery of heat from the flue gas, and the exhaust temperature can be reduced to near the dew point, thus greatly improving the system's thermal efficiency. 2. The combined internal and external recovery of flue gas waste heat can enable the premixed air to obtain extremely high physical sensible heat before combustion, and its temperature may be much higher than the ignition point of the fuel. This results in a high combustion temperature, a fast combustion rate, and more complete combustion. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the combustion device for combined internal and external recovery of flue gas waste heat according to the present invention. Figure 2This is a cross-sectional view of the first heat exchanger of the present invention; Figure 3 For the present invention Figure 2 Enlarged schematic diagram of the structure at point A in the middle; Figure 4 For the present invention Figure 2 Enlarged schematic diagram of the structure at point B; Figure 5 This is a schematic diagram of the blocking component structure of the present invention.

[0016] In the diagram: 1. Burner; 2. Flue gas pipe; 3. First heat exchanger; 301. Shell; 302. Spray chamber; 303. First heat exchange chamber; 304. Second heat exchange chamber; 305. Heat exchange pipe; 306. Spray assembly; 307. Baffle; 308. Baffle plate; 309. Screw; 310. Screw sleeve; 311. Baffle plate; 312. Turntable; 313. Through hole; 314. Magnetic component; 315. Connecting hole; 316. Baffle; 317. Drain port; 318. Drain hole; 4. Second heat exchanger; 5. Purification equipment; 6. Fan; 7. Air guide pipe; 8. Internal waste heat recovery assembly; 801. Front arch; 802. Middle arch; 803. Rear arch; 9. Grate; 10. Feed inlet. Detailed Implementation

[0017] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0018] Example 1 Please see Figure 1 A combustion device for recovering waste heat from flue gas through internal and external combined methods includes: a burner 1, a flue gas pipe 2 connected to the top wall of the burner 1, a grate 9 at the bottom of the inner cavity of the burner 1, and a feed inlet 10 on the side wall of the burner 1.

[0019] Please see Figure 1 The burner 1 is equipped with an internal waste heat recovery assembly 8, and the flue gas pipe 2 is equipped with an external waste heat recovery assembly. Please refer to Figure 2 The external waste heat recovery component includes a first heat exchanger 3; the first heat exchanger 3 includes a spray chamber 302, a first heat exchange chamber 303 and a second heat exchange chamber 304.

[0020] It should be noted that the fuel enters the grate 9 through the feed inlet 10 and is burned. The flue gas produced by combustion is heated by the internal waste heat recovery component 8 and then enters the flue gas pipe 2. The flue gas then enters the spray chamber 302 of the first heat exchanger 3, where it is heated by the spray water and impurities are removed. The flue gas then enters the first heat exchange chamber 303, where it is heated again by the circulating water. After completion, the flue gas is discharged from the first heat exchanger 3. The used circulating water enters the second heat exchange chamber 304 to absorb the heat from the used spray water in the spray chamber 302.

[0021] In this embodiment, as a further optimization, please refer to... Figure 2 The first heat exchanger 3 includes a housing 301 and a partition 308 disposed inside the housing 301. The partition 308 is used to divide the inner cavity of the housing 301 into a spray chamber 302, a first heat exchange chamber 303, and a second heat exchange chamber 304. A spray assembly 306 (including pipes and nozzles disposed on the pipes) is provided at the top of the inner cavity of the spray chamber 302. Heat exchange pipes 305 are provided in the inner cavities of the first heat exchange chamber 303 and the second heat exchange chamber 304. The ends of the two heat exchange pipes 305 are connected to each other. The spray chamber 302 is connected to the first heat exchange chamber 303 and the second heat exchange chamber 304 respectively. The spray chamber 302 and the first heat exchange chamber 303 are distributed sequentially along the flue gas flow direction. The spray chamber 302 and the first heat exchange chamber 303 are both located above the second heat exchange chamber 304. Water enters the heat exchange pipes 305 to absorb heat from the flue gas and the spray water.

[0022] It should be noted that a drain hole 318 is provided on the second heat exchange chamber 304 to drain the spray water inside the second heat exchange chamber 304.

[0023] It should also be noted that using spray water to remove impurities from flue gas can reduce the amount of soot in the flue gas and achieve a preliminary impurity removal effect. This ensures that when the flue gas exchanges heat with the heat exchange pipe 305, the surface of the heat exchange pipe 305 will not be covered by impurities, thus ensuring that the water inside the heat exchange pipe 305 can fully exchange heat with the flue gas.

[0024] In this embodiment, as a further optimization, please refer to... Figure 1The external waste heat recovery assembly also includes a second heat exchanger 4, a purification device 5, and a fan 6. The shell side of the second heat exchanger 4 is connected to the air chamber of the burner 1 through a gas guide pipe 7. The outlet of the fan 6 is connected to the shell side of the second heat exchanger 4. The tube side inlet of the second heat exchanger 4 is connected to the flue gas outlet of the first heat exchange chamber 303. The tube side outlet of the second heat exchanger 4 is connected to the purification device 5 (the purification device 5 refers to the equipment for filtering and purifying flue gas, such as a filter. The equipment for purifying flue gas is existing technology and will not be described in detail here). The fan 6 introduces air into the second heat exchanger 4 to absorb the heat of the flue gas discharged from the first heat exchanger 3, preheating the air. The preheated air enters the air chamber of the burner 1, and the flue gas with absorbed heat enters the purification device 5, is purified, and then discharged.

[0025] It should be noted that the extremely high inlet preheating temperature enables the premixed gas to burn stably even at a lower equivalence ratio, broadening the lean combustion stability range and facilitating the achievement of more efficient low-NOx combustion.

[0026] In this embodiment, as a further optimization, please refer to... Figure 1 The internal waste heat recovery component 8 includes a front arch 801, a middle arch 802, and a rear arch 803. The lower layer is the main combustion zone. High-temperature flue gas first enters the middle layer from the lower layer through the gap between the front arch 801 and the rear arch 803. The rising channel is blocked by the middle arch 802, and the flue gas is diverted to both sides. After being deflected by the furnace walls on both sides, it enters the upper layer and then flows out of the combustion chamber through the flue gas pipe 2. During this process, the front arch 801, the rear arch 803, and the middle arch 802 are directly exposed to the high-temperature flue gas and can absorb the highest quality heat in the flue gas. The heat absorbed can be used to preheat the fuel, air, or premixed gas that is about to enter the combustion reaction, forming a premixed gas with ultra-high physical sensible heat, forming a uniform and stable temperature field, and enhancing the combustion process.

[0027] Example 2 As a further optimization of Example 1, please refer to Figure 2 and Figure 4 A connecting hole 315 is provided on the partition 308, which is used to connect the spray chamber 302 with the first heat exchange chamber 303. Baffles 316 are provided on the upper and lower inner walls of the connecting hole 315, and the upper and lower baffles 316 are staggered. The baffles 316 block the spray water from passing through the connecting hole 315. The bottom height of the inner cavity of the connecting hole 315 gradually increases along the flue gas flow direction, and a drain port 317 is provided on the lower baffle 316. This allows the spray water that enters the connecting hole 315 to flow back into the inner cavity of the spray chamber 302.

[0028] Example 3 As a further optimization of Example 1, please refer to Figure 2 and Figure 5An opening is provided on the partition plate 308, which connects the spray chamber 302 with the second heat exchange chamber 304. A blocking member 307 is provided in the inner cavity of the spray chamber 302, which covers the opening (the blocking member 307 includes a C-shaped plate and two inclined plates on the front and rear side walls of the C-shaped plate, and the two inclined plates will not block the front and rear openings of the C-shaped plate). The blocking member 307 is used to block the opening, reducing the probability of flue gas entering the interior of the second heat exchange chamber 304 through the opening.

[0029] In this embodiment, as a further optimization, please refer to... Figure 2 and Figure 3 The spray chamber 302 has an air inlet, which is connected to the flue gas pipe 2. A threaded sleeve 310 is fixed in the inner cavity of the air inlet, and a screw 309 is installed inside the threaded sleeve 310. A baffle plate 311 is provided on the inner side wall of the spray chamber 302 to block the air inlet. The end of the screw 309 passes through the baffle plate 311 and is connected to the turntable 312. The turntable 312 is in contact with the baffle plate 311. Both the baffle plate 311 and the turntable 312 have several through holes 313. The through hole 313 is misaligned, and the baffle plate 311 is equipped with a magnetic component 314 (such as a magnet). The turntable 312 is made of a metal material that can be magnetically attracted, such as iron. The magnetic component 314 is used to attract the turntable 312. When the burner 1 starts to burn, the generated flue gas gradually enters the interior of the flue gas pipe 2. Because the initial amount of flue gas generated is small, the flue gas cannot break through the restriction of the baffle plate 311 and the turntable 312, and will stay inside the flue gas pipe 2. As the flue gas accumulates, the pressure exerted by the flue gas on the turntable 312 increases. The force increases, exceeding the attraction of the magnetic component 314 to the turntable 312, causing the turntable 312 to begin moving away from the baffle plate 311. This pulls the screw 309, causing it to rotate inside the screw sleeve 310, thus rotating the turntable 312. The through hole 313 on the turntable 312 then aligns with the through hole 313 on the baffle plate 311. The flue gas inside the flue pipe 2 enters the spray chamber 302 through the through hole 313 and the gap between the baffle plate 311 and the turntable 312, allowing the flue gas to accumulate to a certain amount before entering the spray chamber. In chamber 302, spray water is saved, and several through holes 313 can disperse the flue gas, allowing the flue gas to fully contact the spray water. When combustion stops and the flue gas decreases, the pressure on the turntable 312 decreases. Under the adsorption of the magnetic component 314, the turntable 312 moves closer to the baffle plate 311. With the cooperation of the screw 309 and the screw sleeve 310, the turntable 312 rotates and fits against the baffle plate 311, causing the through holes 313 on the turntable 312 to be misaligned with the through holes 313 on the baffle plate 311, thus sealing the air inlet.

[0030] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A combustion device for combined internal and external recovery of flue gas waste heat, characterized in that, include: The burner (1) and the flue gas pipe (2) provided on the burner (1) are provided with an internal waste heat recovery assembly (8) and an external waste heat recovery assembly on the flue gas pipe (2). The external waste heat recovery assembly includes a first heat exchanger (3); The first heat exchanger (3) includes a spray chamber (302), a first heat exchange chamber (303), and a second heat exchange chamber (304). The spray chamber (302) is used to absorb the heat of the flue gas discharged from the flue gas pipe (2) and remove impurities by using spray water. The first heat exchange chamber (303) is used to absorb the heat of the flue gas discharged from the spray chamber (302) again by using circulating water. The second heat exchange chamber (304) is used to absorb the heat of the spray water after the first heat exchange chamber (303) has been used by using the circulating water after the first heat exchange chamber (303) has been used.

2. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 1, characterized in that, The first heat exchanger (3) includes a shell (301) and a partition (308) disposed inside the shell (301). The partition (308) is used to divide the inner cavity of the shell (301) into a spray chamber (302), a first heat exchange chamber (303) and a second heat exchange chamber (304). The spray chamber (302) is provided with a spray assembly (306). The first heat exchange chamber (303) and the second heat exchange chamber (304) are provided with heat exchange pipes (305) that communicate with each other. The spray chamber (302) is connected to the first heat exchange chamber (303) and the second heat exchange chamber (304) respectively.

3. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 2, characterized in that, The spray chamber (302) and the first heat exchange chamber (303) are distributed sequentially along the flue gas flow direction, and both the spray chamber (302) and the first heat exchange chamber (303) are located above the second heat exchange chamber (304).

4. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 3, characterized in that, The partition (308) is provided with a communication hole (315) for connecting the spray chamber (302) and the first heat exchange chamber (303), and baffles (316) are alternately provided on the upper and lower inner walls of the communication hole (315).

5. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 4, characterized in that, The height of the bottom of the inner cavity of the connecting hole (315) gradually increases along the flue gas flow direction, and the lower baffle (316) is provided with a drain port (317).

6. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 2, characterized in that, The partition (308) is provided with an opening for communicating the spray chamber (302) with the second heat exchange chamber (304), and the spray chamber (302) is provided with a blocking member (307) for covering the opening.

7. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 1, characterized in that, The spray chamber (302) is provided with an air inlet for communicating with the flue gas pipe (2). A screw sleeve (310) is provided in the air inlet. A screw rod (309) is provided in the screw sleeve (310). A baffle plate (311) is provided in the spray chamber (302) for blocking the air inlet. The screw rod (309) passes through the baffle plate (311) and is connected to the turntable (312). Both the baffle plate (311) and the turntable (312) are provided with through holes (313). A magnetic component (314) for adsorbing the turntable (312) is provided on the baffle plate (311).

8. The combustion device for combined internal and external recovery of flue gas waste heat according to claim 1, characterized in that, The external waste heat recovery assembly also includes a second heat exchanger (4), a purification device (5) and a fan (6). The second heat exchanger (4) is connected to the burner (1) through a gas duct (7). The fan (6) is used to introduce air into the second heat exchanger (4) to absorb the heat of the flue gas discharged from the first heat exchanger (3). The purification device (5) is used to purify the flue gas discharged from the second heat exchanger (4).

9. A combustion device for combined internal and external recovery of flue gas waste heat according to claim 1, characterized in that, The internal waste heat recovery assembly (8) includes a front arch (801), a middle arch (802) and a rear arch (803). The front arch (801), middle arch (802) and rear arch (803) divide the inner cavity of the burner (1) into three layers from top to bottom.

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