High-temperature flue gas multi-layer furnace waste heat utilization system and method

Abstract

The invention discloses a high-temperature flue gas multi-layer furnace waste heat utilization system and method.The system comprises a multi-layer cooling furnace and a multi-layer heating furnace, the multi-layer cooling furnace and the multi-layer heating furnace each comprise a furnace body, a driving system, a rotating shaft, an inner rotating rake, an outer rotating rake, an inner layer table, an outer layer table and a cover plate, and a low-temperature flue gas pipe and a heat exchange medium inlet are arranged at the top of the multi-layer cooling furnace; a high-temperature flue gas pipe and a heat exchange medium outlet are arranged at the bottom of the multi-layer temperature rising furnace, a heating gas pipe and a heat exchange medium inlet are arranged at the top of the multi-layer temperature rising furnace, and a normal-temperature gas pipe and a heat exchange medium outlet are arranged at the bottom of the multi-layer temperature rising furnace; according to the method, the heat value of high-temperature flue gas is transmitted to the heat exchange medium through the multi-layer cooling furnace, the heated high-temperature heat exchange medium transmits heat to normal-temperature gas through the multi-layer heating furnace, and therefore the gas preheating function is achieved; and the maximum utilization of the high-temperature flue gas waste heat is realized.

Description

Technical Field

[0001] The present invention relates to the field of high-temperature flue gas treatment, and in particular to a multi-layer furnace waste heat utilization system and method for recovering and utilizing the waste heat of high-temperature flue gas generated by the combustion of industrial kilns. Background Art

[0003] Currently, the treatment of high-temperature flue gas often uses a smoke hood and a waste heat boiler to recover the waste heat of the high-temperature flue gas, convert the calorific value of the high-temperature flue gas into pressurized steam, and then use it for waste heat power generation and other applications. By this method, the waste heat of the high-temperature flue gas is recovered. Taking the waste heat energy recovery as 60% and the steam power generation energy efficiency conversion as 30%, after deducting the waste heat dissipation of the low-temperature section flue gas, the overall waste heat utilization rate is only about 20%. Therefore, it can be seen that the waste heat utilization efficiency of high-temperature flue gas in the current industrial system is still at a relatively low level, and there is an urgent need to develop new waste heat recovery and utilization processes.

[0004] Traditional high-temperature flue gas waste heat utilization is based on the heat exchange between high-temperature flue gas and water in principle, converting high-temperature flue gas into pressurized steam. The main components of high-temperature flue gas are often mainly N2, CO2, and H2O, that is, the oxygen in the air has been consumed and converted into CO2 and H2O, and it contains a high concentration of dust, and it no longer has the utilization value of material components. The emission of high-temperature flue gas often corresponds to the air or oxygen required for combustion. Using high-temperature flue gas to heat materials is the most efficient way to utilize its waste heat resources. If it can be directly used to heat air or oxygen, it will be the best way to realize its waste heat utilization. In industrial production, high-temperature flue gas has been used for drying, heating solid raw materials such as ores, etc., but there is still a lack of cases where high-temperature flue gas directly heats air. The main reason is that the heat conduction efficiency between gases is low, and when convective heat transfer mixes high-temperature flue gas and air together, the oxygen cannot be effectively utilized and the energy utilization rate is even lower. In smelting and other production enterprises, hot blast stoves often need to directly use gas and other fuels for heating the hot blast stove. Due to the large amount of dust contained in high-temperature flue gas, the heat storage function of the checker bricks in the hot blast stove will be blocked by dust, thus losing the heat storage function and unable to be utilized. Therefore, there is an urgent need to develop new waste heat utilization system methods to directly use high-temperature flue gas for preheating air and oxygen, so as to maximize the utilization of the waste heat of high-temperature flue gas. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a high-temperature flue gas multi-layer furnace waste heat utilization system and method, which uses solid materials as the heat transfer medium, and uses a multi-layer cooling furnace and a multi-layer heating furnace to respectively realize the cooling of high-temperature flue gas and the heating of normal-temperature gas. First, the calorific value of the high-temperature flue gas is transferred to the medium through the multi-layer cooling furnace, and then the heated high-temperature medium uses the multi-layer heating furnace to transfer the heat to the normal-temperature gas, thereby realizing the gas preheating function, and further realizing the maximum utilization of the waste heat of the high-temperature flue gas.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A waste heat utilization system for high-temperature flue gas multi-layer furnace, comprising a multi-layer cooling furnace, a multi-layer heating furnace, a first conveying device, a second conveying device, and a dust removal device; Both the multi-layer cooling furnace and the multi-layer heating furnace include a furnace body, a drive system, a rotating shaft, an inner rotating rake, an outer rotating rake, an inner layer platform, an outer layer platform, and a cover plate. Inside the furnace body, multiple layers of inner layer platforms and outer layer platforms are alternately arranged from top to bottom. The inner layer platforms and outer layer platforms are used to carry heat exchange media. The outer edges of the inner layer platforms and outer layer platforms are connected to the inner wall of the furnace body. A heat exchange medium downward port is provided at a position close to the outer edge of the outer layer platform. The rotating shaft passes through the inner layer platforms and outer layer platforms from top to bottom at the center of the furnace body. A gap is provided between the inner edge of the inner layer platform and the rotating shaft. A cover plate is provided between the inner edge of the outer layer platform and the rotating shaft. Multiple groups of inner rotating rakes and outer rotating rakes are alternately arranged on the rotating shaft. The inner rotating rakes are located above the outer layer platform, and the outer rotating rakes are located above the outer layer platform. The drive system is connected to the rotating shaft and is used to drive the rotating shaft to rotate; A low-temperature flue gas pipe and a heat exchange medium inlet are provided at the top of the furnace body of the multi-layer cooling furnace. A high-temperature flue gas pipe and a heat exchange medium outlet are provided at the bottom of the furnace body of the multi-layer cooling furnace. A heating gas pipe and a heat exchange medium inlet are provided at the top of the furnace body of the multi-layer heating furnace. A normal-temperature gas pipe and a heat exchange medium outlet are provided at the bottom of the furnace body of the multi-layer heating furnace. The heat exchange medium outlet of the multi-layer cooling furnace is connected to the heat exchange medium inlet of the multi-layer heating furnace through the first conveying device. The heat exchange medium outlet of the multi-layer heating furnace is connected to the heat exchange medium inlet of the multi-layer cooling furnace through the second conveying device. The low-temperature flue gas pipe is connected to the dust removal device, and a blower is provided on the normal-temperature gas pipe.

[0007] Further, it also includes a floor and a bearing platform. The bottom of the multi-layer heating furnace is fixed on the floor. The bearing platform is arranged above the multi-layer heating furnace, and the bottom of the bearing platform is fixed on the floor. The bottom of the multi-layer cooling furnace is fixed on the bearing platform.

[0008] Further, the first heat exchange medium conveying device includes a discharge chute, a discharge valve, and a chute. The upper end of the discharge chute is connected to the heat exchange medium outlet of the multi-layer cooling furnace. The lower end of the discharge chute is connected to the upper end of the chute through the discharge valve. The lower end of the chute is connected to the heat exchange medium inlet of the multi-layer heating furnace; The second conveying device includes a bottom plate chain conveyor, a hoist, and a top plate chain conveyor. The feeding end of the bottom plate chain conveyor is connected to the heat exchange medium outlet of the multi-layer heating furnace. The discharging end of the bottom plate chain conveyor is connected to the feeding end of the top plate chain conveyor through the hoist. The discharging end of the top plate chain conveyor is connected to the heat exchange medium inlet of the multi-layer cooling furnace.

[0009] Further, the dust removal device includes a bag filter, an induced draft fan, and a chimney connected in sequence.

[0010] Further, water cooling pipes or air cooling pipes are provided inside the rotating shaft, the inner rotating rake, and the outer rotating rake.

[0011] Furthermore, the total number of the inner layer platforms and the outer layer platforms in the furnace body is not less than 3 layers.

[0012] The method for utilizing the waste heat of the high-temperature flue gas multi-layer furnace in the above-mentioned high-temperature flue gas multi-layer furnace waste heat utilization system includes: Inject the heat exchange medium into the furnace body from the heat exchange medium inlet of the multi-layer cooling furnace. Drive the rotation of the rotating shaft through the drive system to drive the inner rotating rake and the outer rotating rake to rotate. The inner rotating rake pushes the heat exchange medium to gradually travel from the outer edge of the inner layer platform to the inner edge of the inner layer platform, and then falls to the inner edge of the outer layer platform through the gap between the inner edge of the inner layer platform and the rotating shaft. The outer rotating rake pushes the heat exchange medium to gradually travel from the inner edge of the outer layer platform to the outer edge of the outer layer platform, and then falls to the outer edge of the inner layer platform through the heat exchange medium downward outlet of the outer layer platform. The heat exchange medium gradually descends to the bottom of the multi-layer cooling furnace in the above-mentioned traveling manner in the multi-layer cooling furnace. The flue gas discharged from the industrial kiln is introduced into the bottom of the multi-layer cooling furnace through the high-temperature flue gas pipe, and sequentially passes through each layer of the inner layer platform and the outer layer platform from bottom to top in the furnace body of the multi-layer cooling furnace and exchanges heat with the heat exchange medium. The cooled flue gas is discharged through the low-temperature flue gas pipe of the multi-layer cooling furnace, and then is discharged after dust removal through the dust removal device. The heated heat exchange medium is discharged through the heat exchange medium outlet of the multi-layer cooling furnace; Transport the heat exchange medium discharged from the heat exchange medium outlet of the multi-layer cooling furnace to the multi-layer heating furnace through the first transport device, and inject it into the furnace body from the heat exchange medium inlet of the multi-layer cooling furnace. The heat exchange medium gradually descends to the bottom of the multi-layer heating furnace in the same traveling manner as in the multi-layer cooling furnace in the multi-layer heating furnace. The normal-temperature gas is introduced into the bottom of the multi-layer heating furnace through the blower and the normal-temperature gas pipe, and sequentially passes through each layer of the inner layer platform and the outer layer platform from bottom to top in the furnace body of the multi-layer heating furnace and exchanges heat with the heat exchange medium. The heated gas is discharged through the heating gas pipe of the multi-layer heating furnace, and the cooled heat exchange medium is discharged through the heat exchange medium outlet of the multi-layer heating furnace; Return the heat exchange medium discharged from the heat exchange medium outlet of the multi-layer heating furnace to the multi-layer cooling furnace through the second transport device, and inject it into the furnace body from the heat exchange medium inlet of the multi-layer cooling furnace to exchange heat with the flue gas again.

[0013] Furthermore, the heat exchange medium is alumina-based or iron-oxide-based solid particles, and the maximum particle size does not exceed 50 mm.

[0014] Furthermore, the temperature of the flue gas introduced into the multi-layer cooling furnace through the high-temperature flue gas pipe is not less than 500 °C, the temperature of the flue gas discharged through the low-temperature flue gas pipe of the multi-layer cooling furnace does not exceed 200 °C, and the temperature of the gas discharged through the heating gas pipe of the multi-layer heating furnace is not less than 400 °C.

[0015] Furthermore, the temperature of the heat exchange medium discharged from the heat exchange medium outlet of the multi-layer cooling furnace is not less than 400 °C, and the temperature of the heat exchange medium discharged from the heat exchange medium outlet of the multi-layer heating furnace does not exceed 200 °C; The residence time of the heat exchange medium in the multi-layer cooling furnace and the multi-layer heating furnace is 15 to 60 minutes, and the time taken for the heat exchange medium to complete one cycle through the multi-layer cooling furnace, the multi-layer heating furnace, the first conveying device, and the second conveying device is 40 to 140 minutes; the stacking thickness of the heat exchange medium on the inner layer platform and the outer layer platform in the multi-layer cooling furnace and the multi-layer heating furnace does not exceed 100 mm.

[0016] Advantages: The present invention uses solid materials as the heat transfer medium, and adopts a multi-layer cooling furnace and a multi-layer heating furnace to respectively cool the high-temperature flue gas and heat the normal-temperature gas. The calorific value of the high-temperature flue gas is first transferred to the heat exchange medium through the multi-layer cooling furnace, and then the heated high-temperature heat exchange medium uses the multi-layer heating furnace to transfer the heat to the normal-temperature gas, thereby realizing the gas preheating function and maximizing the utilization of the waste heat of the high-temperature flue gas.

[0017] Processing high-temperature flue gas by this method has system advantages such as high waste heat recovery rate. In terms of waste heat recovery, through this method of treatment, the effective utilization rate of the waste heat of high-temperature flue gas exceeds 80%, compared with only about 20% utilization rate of the traditional process, and the waste heat recovery efficiency is increased by 5 times. In the treatment of high-temperature flue gas, the sedimentation and cooling of high-temperature flue gas can be realized, and the treated high-temperature flue gas can be directly discharged through a bag filter, greatly reducing the system investment and operating cost of the existing dust removal process.

[0018] The invention has the advantages of simple system process equipment, stable and reliable equipment operation, simple operation, low system failure, small investment, small floor area, and high production efficiency. There are many industrial kilns in industries such as metallurgy and building materials in our country, and the generation amount of high-temperature flue gas and waste gas is extremely large. The invention has a huge market application space. Compared with traditional waste heat utilization boilers, the invention has significant technical and market advantages. It can not only be used for the treatment of flue gas emissions from industrial kilns such as metallurgy, but also provide reliable process equipment support for the utilization of combustion waste gas such as waste incineration and coal-fired boilers, and has outstanding commercial operation value. Brief Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the high-temperature flue gas multi-layer furnace waste heat utilization system of the present invention.

[0020] Figure 2 It is a schematic diagram of the inner rotary rake and the outer rotary rake rotating to push materials.

[0021] In the figure: 1 - High-temperature flue gas pipe; 2 - Multi-layer cooling furnace; 3 - Multi-layer heating furnace; 4 - Floor; 5 - Bearing platform; 6 - Furnace body; 7 - Drive system; 8 - Rotating shaft; 9 - Inner rotating rake; 10 - Outer rotating rake; 11 - Inner layer platform; 12 - Outer layer platform; 13 - Rake teeth; 14 - Cover plate; 15 - Head; 16 - Heat exchange medium; 17 - Discharge chute; 18 - Discharge valve; 19 - Chute; 20 - Bottom plate chain conveyor; 21 - Hoist; 22 - Top plate chain conveyor; 23 - Low-temperature flue gas pipe; 24 - Bag filter; 25 - Induced draft fan; 26 - Chimney; 27 - Normal temperature gas pipe; 28 - Blower; 29 - Heating gas pipe. Specific embodiments

[0022] The present invention will be further explained below with reference to the accompanying drawings.

[0023] As Figure 1 shown, a high-temperature flue gas multi-layer furnace waste heat utilization system of the present invention includes a multi-layer cooling furnace 2, a multi-layer heating furnace 3, a first conveying device, a second conveying device, and a dust removal device.

[0024] Both the multi-layer cooling furnace 2 and the multi-layer heating furnace 3 include a furnace body 6, a drive system 7, a rotating shaft 8, an inner rotating rake 9, an outer rotating rake 10, an inner layer platform 11, an outer layer platform 12, and a cover plate 14. Inside the furnace body 6, multiple layers of inner layer platforms 11 and outer layer platforms 12 are alternately arranged from top to bottom. The inner layer platforms 11 and outer layer platforms 12 are used to carry the heat exchange medium 16. The outer edges of the inner layer platforms 11 and outer layer platforms 12 are connected to the inner wall of the furnace body 6. A heat exchange medium downward outlet is provided at a position near the outer edge of the outer layer platform 12. The rotating shaft 8 penetrates the inner layer platform 11 and the outer layer platform 12 from top to bottom at the center of the furnace body 6. A gap is provided between the inner edge of the inner layer platform 11 and the rotating shaft 8, and the heat exchange medium 16 can fall through this gap. A cover plate 14 is provided between the inner edge of the outer layer platform 12 and the rotating shaft 8 to prevent the heat exchange medium 16 from falling between the inner edge of the outer layer platform 12 and the rotating shaft 8. Multiple groups of inner rotating rakes 9 and outer rotating rakes 10 are alternately arranged on the rotating shaft 8. The inner rotating rake 9 is located above the outer layer platform 12, and the outer rotating rake 10 is located above the outer layer platform 12. The drive system 7 is connected to the rotating shaft 8 and is used to drive the rotating shaft 8 to rotate.

[0025] At the top of the furnace body 6 of the multi-layer cooling furnace 2, a low-temperature flue gas pipe 23 and a heat exchange medium inlet are provided. At the bottom of the furnace body 6 of the multi-layer cooling furnace 2, a high-temperature flue gas pipe 1 and a heat exchange medium outlet are provided. At the top of the furnace body 6 of the multi-layer heating furnace 3, a heating gas pipe 29 and a heat exchange medium inlet are provided. At the bottom of the furnace body 6 of the multi-layer heating furnace 3, a normal temperature gas pipe 27 and a heat exchange medium outlet are provided. The heat exchange medium outlet of the multi-layer cooling furnace 2 is connected to the heat exchange medium inlet of the multi-layer heating furnace 3 through the first conveying device. The heat exchange medium outlet of the multi-layer heating furnace 3 is connected to the heat exchange medium inlet of the multi-layer cooling furnace 2 through the second conveying device. The low-temperature flue gas pipe 23 is connected to the dust removal device, and a blower 28 is provided on the normal temperature gas pipe 27.

[0026] The multi-layer cooling furnace 2 and the multi-layer heating furnace 3 are arranged one above the other, and are fixed through the floor 4 and the bearing platform 5 respectively. The bottom of the multi-layer heating furnace 3 is fixed on the floor 4, the bearing platform 5 is arranged above the multi-layer heating furnace 3, the bottom of the bearing platform 5 is fixed on the floor 4, and the bottom of the multi-layer cooling furnace 2 is fixed on the bearing platform 5. The furnace bodies 6 of the multi-layer cooling furnace 2 and the multi-layer heating furnace 3 are both cylindrical steel structure furnace bodies, with refractory materials installed inside, and the thickness of the refractory materials is 80 - 300 mm. The bearing platform 5 is a concrete or steel structure platform. Sealing heads 15 are evenly distributed on the furnace bodies 6 of the multi-layer cooling furnace 2 and the multi-layer heating furnace 3. The sealing heads 15 are steel structure enclosures, and are fixed by welding or bolts, and are used to seal the tops of the furnace bodies 6 of the multi-layer cooling furnace 2 and the multi-layer heating furnace 3. The total number of the inner platforms 1 and the outer platforms 12 in each furnace body 6 is not less than 3 layers. The inner platforms 11 and the outer platforms 12 are made of steel bars and high-temperature resistant materials by masonry, and are used as carriers of the heat exchange medium 16. The outer edges of the inner platforms 11 and the outer platforms 12 and the inner wall of the furnace body 6 are connected into one body by steel bars and high-temperature resistant materials by masonry. The thickness of the inner platforms 11 and the outer platforms 12 is not less than 100 mm.

[0027] A plurality of inner rotary rakes 9 and outer rotary rakes 10 in each group are arranged around the rotating shaft 8, and a plurality of rake teeth 11 are evenly distributed below each inner rotary rake 9 and outer rotary rake 10. Figure 2 As shown in the figure, when the drive system 7 drives the rotating shaft 8 to rotate, the rotating shaft 8 drives the inner rotary rake 9 and the outer rotary rake 10 to rotate, and the installation angles of the rake teeth 13 on the inner rotary rake 9 and the outer rotary rake 10 are in opposite directions. Figure 2 Taking [example] as an example, when the inner rotary rake 9 and the outer rotary rake 10 move counterclockwise along with the rotating shaft 8, the rake teeth 13 on the inner rotary rake 9 will push the heat exchange medium 16 to move outward along the outer edge when rotating on the outer platform 12 because the tooth surface faces outward in the moving direction; the rake teeth 13 on the outer rotary rake 10 will push the heat exchange medium 16 to move inward along the inner edge when rotating on the inner platform 11 because the tooth surface faces inward in the moving direction; therefore, the inner rotary rake 9 and the outer rotary rake 10 will cause the heat exchange medium 16 to move in opposite directions in the radial direction along with the movement of the rotating shaft 8. When the inner rotary rake 9 and the outer rotary rake 10 rotate, the rake teeth 11 of the inner rotary rake 9 can push the heat exchange medium on the inner platform 11 inward, and the rake teeth 11 of the outer rotary rake 10 can push the heat exchange medium on the outer platform 12 outward. The rotating shaft 8, the inner rotary rake 9, the outer rotary rake 10, the rake teeth 13, and the cover plate 14 are all made of heat-resistant steel structure materials. The rotating shaft 8, the inner rotary rake 9, and the outer rotary rake 10 are provided with water-cooled pipes or air-cooled pipes, and water cooling protection is preferably adopted. The rake teeth 13 are made of high-temperature resistant and wear-resistant steel materials, and the thickness is not less than 20 mm. The drive system 7 is driven by a frequency conversion motor, and the drive system 7 is arranged at the bottom of the furnace body 6 and is connected to the lower end of the rotating shaft 8, and the connection method is welding or bolt fixing.

[0028] The first heat transfer medium conveying device includes a discharge chute 17, a discharge valve 18, and a chute 19. The upper end of the discharge chute 17 is connected to the heat transfer medium outlet of the multi-layer cooling furnace 2, the lower end of the discharge chute 17 is connected to the upper end of the chute 19 through the discharge valve 18, and the lower end of the chute 19 is connected to the heat transfer medium inlet of the multi-layer heating furnace 3. Among them, the discharge chute 17 and the chute 19 are made of steel structure materials. The discharge valve 18 is a high-temperature resistant discharge valve, which can stably make the heat transfer medium 16 fall from the multi-layer cooling furnace 2 into the multi-layer heating furnace 3, and at the same time has good air tightness, preventing the cross-flow between the multi-layer cooling furnace 2 and the multi-layer heating furnace 3, which is not conducive to waste heat recovery and utilization.

[0029] The second conveying device includes a bottom plate chain conveyor 20, a hoist 21, and a top plate chain conveyor 22. The feeding end of the bottom plate chain conveyor 20 is connected to the heat transfer medium outlet of the multi-layer heating furnace 3, the discharging end of the bottom plate chain conveyor 20 is connected to the feeding end of the top plate chain conveyor 22 through the hoist 21, and the discharging end of the top plate chain conveyor 22 is connected to the heat transfer medium inlet of the multi-layer cooling furnace 2. Among them, the plate chain conveyor 20, the top plate chain conveyor 22, and the hoist 21 are all made of materials that can withstand high temperatures not lower than 200 °C to make the conveying container, and the hoist 21 is a bucket elevator. The chimney 26 is a steel structure chimney.

[0030] The high-temperature flue gas pipe 1, the low-temperature flue gas pipe 23, the normal-temperature gas pipe 27, and the heating gas pipe 29 are all steel structure pipes. Among them, refractory materials are installed inside the high-temperature flue gas pipe 1 and the heating gas pipe 29, and the thickness of the refractory materials is not less than 80 mm. The dust removal device includes a bag filter 24, an induced draft fan 25, and a chimney 26 connected in sequence, and the connection method is welding or bolt fixing. The induced draft fan 25 and the blower 28 are both driven by variable frequency motors The method for utilizing the waste heat of the high-temperature flue gas multi-layer furnace based on the above high-temperature flue gas multi-layer furnace waste heat utilization system of the present invention includes: The heat exchange medium is introduced into the furnace body 6 from the heat exchange medium inlet of the multi-layer cooling furnace 2. The driving system 7 drives the rotation of the rotating shaft 8 to drive the inner rotating rake 9 and the outer rotating rake 10 to rotate. The inner rotating rake 9 pushes the heat exchange medium (16) to gradually travel from the outer edge of the inner layer table 11 to the inner edge of the inner layer table 11, and then falls to the inner edge of the outer layer table 12 through the gap between the inner edge of the inner layer table 11 and the rotating shaft 8. The outer rotating rake 10 pushes the heat exchange medium 16 to gradually travel from the inner edge of the outer layer table 12 to the outer edge of the outer layer table 12, and then falls to the outer edge of the inner layer table 11 through the heat exchange medium downward outlet of the outer layer table 12. The heat exchange medium 16 gradually descends to the bottom of the multi-layer cooling furnace 2 in the above-mentioned traveling manner. The flue gas discharged from the industrial kiln furnace is introduced into the bottom of the multi-layer cooling furnace 2 through the high-temperature flue gas pipe 1, and sequentially passes through each layer of the inner layer table 11 and the outer layer table 12 from bottom to top in the furnace body 6 of the multi-layer cooling furnace 2 to exchange heat with the heat exchange medium. The cooled flue gas is discharged through the low-temperature flue gas pipe 23 of the multi-layer cooling furnace 2, and then discharged after dust removal by the dust removal device. The heated heat exchange medium is discharged through the heat exchange medium outlet of the multi-layer cooling furnace 2; The heat exchange medium discharged from the heat exchange medium outlet of the multi-layer cooling furnace 2 is transported to the multi-layer heating furnace 3 through the first conveying device, and is introduced into the furnace body 6 from the heat exchange medium inlet of the multi-layer cooling furnace 2. The heat exchange medium 16 gradually descends to the bottom of the multi-layer heating furnace 3 in the same traveling manner as in the multi-layer cooling furnace 2. The normal-temperature gas is introduced into the bottom of the multi-layer heating furnace 3 through the normal-temperature gas pipe 27 by the blower 28. The heat exchange medium exchanges heat with the heat exchange medium while sequentially passing through each layer of the inner layer table 11 and the outer layer table 12 from bottom to top in the furnace body 6 of the multi-layer heating furnace 3. The heated gas is discharged through the heating gas pipe 29 of the multi-layer heating furnace 3, and the cooled heat exchange medium is discharged through the heat exchange medium outlet of the multi-layer heating furnace 3; The heat exchange medium discharged from the heat exchange medium outlet of the multi-layer heating furnace 3 is returned to the multi-layer cooling furnace 2 through the second conveying device, and is introduced into the furnace body 6 from the heat exchange medium inlet of the multi-layer cooling furnace 2 to exchange heat with the flue gas introduced into the multi-layer cooling furnace 2 again.

[0031] According to the above method, the multi-layer cooling furnace 2 is used to cool the flue gas discharged from the industrial kiln furnace and heat the heat exchange medium, and the multi-layer heating furnace 3 is used to heat the normal-temperature gas and cool the heat exchange medium. The heat exchange medium 16 is recycled in the multi-layer cooling furnace 2 and the multi-layer heating furnace 3, realizing the waste heat utilization and ultra-clean emission of the high-temperature flue gas.

[0032] Among them, the heat exchange medium 16 is alumina-based solid particles or iron oxide-based solid particles, and the maximum particle size does not exceed 50 mm. Considering the comprehensive heat exchange performance and system cost, the alumina content in the alumina-based solid particles is not less than 50%, and the iron oxide content in the iron oxide-based solid particles is not less than 40%.

[0033] The flue gas temperature introduced into the multi-layer cooling furnace 2 through the high-temperature flue gas pipe 1 is not lower than 500 °C, the flue gas temperature discharged through the low-temperature flue gas pipe 23 of the multi-layer cooling furnace 2 does not exceed 200 °C, and the gas temperature discharged through the heating gas pipe 29 of the multi-layer heating furnace 3 is not lower than 400 °C.

[0034] The heat exchange medium temperature discharged from the heat exchange medium outlet of the multi-layer cooling furnace 2 is not lower than 400 °C, and the heat exchange medium temperature discharged from the heat exchange medium outlet of the multi-layer heating furnace 3 does not exceed 200 °C.

[0035] The residence time of the heat medium 16 in the multi-layer cooling furnace 2 and the multi-layer heating furnace 3 is 15 to 60 minutes, and the time taken for the heat exchange medium 16 to complete one cycle through the multi-layer cooling furnace 2, the multi-layer heating furnace 3, the first conveying device, and the second conveying device is 40 to 140 minutes. The stacking thickness of the heat exchange medium 16 on the inner layer platform 11 and the outer layer platform 12 in the multi-layer cooling furnace 2 and the multi-layer heating furnace 3 does not exceed 100 mm.

[0036] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A high-temperature flue gas multi-layer furnace waste heat utilization system, characterized in that: It comprises a multi-layer temperature-lowering furnace (2), a multi-layer temperature-raising furnace (3), a first conveying device, a second conveying device, and a dust removal device; The multi-layer cooling furnace (2) and the multi-layer heating furnace (3) both comprise a furnace body (6), a driving system (7), a rotating shaft (8), an inner rotating rake (9), an outer rotating rake (10), an inner platform (11), an outer platform (12), and a cover plate (14). Multiple layers of inner platforms (11) and outer platforms (12) are alternately arranged from top to bottom inside the furnace body (6). The inner platforms (11) and the outer platforms (12) are used to carry a heat exchange medium (16). The outer edges of the inner platforms (11) and the outer platforms (12) are connected to the inner wall of the furnace body (6). A heat exchange medium (16) is arranged near the outer edge of the outer platform (12). A heat exchange medium downward port, a rotating shaft (8) passes through the inner platform (11) and the outer platform (12) from top to bottom in the center of the furnace body (6), a gap is provided between the inner edge of the inner platform (11) and the rotating shaft (8), a cover plate (14) is provided between the inner edge of the outer platform (12) and the rotating shaft (8), a plurality of groups of inner rotating rakes (9) and outer rotating rakes (10) are alternately arranged on the rotating shaft (8), the inner rotating rake (9) is located on the upper side of the outer platform (12), and the outer rotating rake (10) is located on the upper side of the outer platform (12), and a driving system (7) is connected to the rotating shaft (8) for driving the rotating shaft (8) to rotate; A low-temperature flue gas pipe (23) and a heat exchange medium inlet are arranged at the top of the furnace body (6) of the multi-layer cooling furnace (2); a high-temperature flue gas pipe (1) and a heat exchange medium outlet are arranged at the bottom of the furnace body (6) of the multi-layer cooling furnace (2); a heating gas pipe (29) and a heat exchange medium inlet are arranged at the top of the furnace body (6) of the multi-layer heating furnace (3); a normal-temperature gas pipe (27) and a heat exchange medium outlet are arranged at the bottom of the furnace body (6) of the multi-layer heating furnace (3); the heat exchange medium outlet of the multi-layer cooling furnace (2) is connected to the heat exchange medium inlet of the multi-layer heating furnace (3) via a first conveying device; the heat exchange medium outlet of the multi-layer heating furnace (3) is connected to the heat exchange medium inlet of the multi-layer cooling furnace (2) via a second conveying device; the low-temperature flue gas pipe (23) is connected to a dust removal device; and a blower (28) is arranged on the normal-temperature gas pipe (27).

2. A high-temperature flue gas multi-layer furnace waste heat utilization system according to claim 1, characterized in that: It also includes a floor (4) and a support platform (5), wherein the bottom of the multi-layer heating furnace (3) is fixed on the floor (4), the support platform (5) is arranged above the multi-layer heating furnace (3), the bottom of the support platform (5) is fixed on the floor (4), and the bottom of the multi-layer cooling furnace (2) is fixed on the support platform (5).

3. The high-temperature flue gas multi-layer furnace waste heat utilization system according to claim 1 is characterized in that: The first heat exchange medium conveying device comprises a discharge trough (17), a discharge valve (18), and a chute (19); the upper end of the discharge trough (17) is connected to the heat exchange medium outlet of the multi-layer cooling furnace (2); the lower end of the discharge trough (17) is connected to the upper end of the chute (19) via the discharge valve (18); and the lower end of the chute (19) is connected to the heat exchange medium inlet of the multi-layer heating furnace (3); The second conveying device comprises a bottom plate chain conveyor (20), an elevator (21), and a top plate chain conveyor (22); the loading end of the bottom plate chain conveyor (20) is connected to the heat exchange medium outlet of the multi-layer heating furnace (3); the unloading end of the bottom plate chain conveyor (20) is connected to the loading end of the top plate chain conveyor (22) via the elevator (21); and the unloading end of the top plate chain conveyor (22) is connected to the heat exchange medium inlet of the multi-layer cooling furnace (2).

4. The high-temperature flue gas multi-layer furnace waste heat utilization system according to claim 1 is characterized in that: The dust removal device comprises a bag dust collector (24), an induced draft fan (25), and a chimney (26) which are connected in sequence.

5. The high-temperature flue gas multi-layer furnace waste heat utilization system according to claim 1 is characterized in that: The rotating shaft (8), the inner rotating rake (9) and the outer rotating rake (10) are provided with water cooling pipes or air cooling pipes.

6. According to the high-temperature flue gas multi-layer furnace waste heat utilization system according to claim 1, it is characterized in that: The total number of inner platforms (11) and outer platforms (12) in the furnace body (6) is not less than 3 layers.

7. A method for utilizing waste heat from a high-temperature flue gas multi-layer furnace based on the waste heat utilization system for a high-temperature flue gas multi-layer furnace according to claim 1, characterized in that: The method includes: A heat exchange medium (16) is introduced into the furnace body (6) from the heat exchange medium inlet of the multi-layer cooling furnace (2), and the driving system (7) drives the rotating shaft (8) to rotate and drives the inner rotating rake (9) and the outer rotating rake (10) to rotate. The inner rotating rake (9) pushes the heat exchange medium (16) from the outer edge of the inner platform (11) to the inner edge of the inner platform (11), and falls through the gap between the inner edge of the inner platform (11) and the rotating shaft (8) to the inner edge of the outer platform (12). The outer rotating rake (10) pushes the heat exchange medium (16) from the inner edge of the outer platform (12) to the outer edge of the outer platform (12), and falls through the heat exchange medium descending port of the outer platform (12) to the inner layer. The heat exchange medium (16) gradually descends to the bottom of the multi-layer cooling furnace (2) in the multi-layer cooling furnace (2) according to the above-mentioned moving mode. The flue gas discharged from the industrial kiln (2) passes through the high-temperature flue gas pipe (1) into the bottom of the multi-layer cooling furnace (2). In the furnace body (6) of the multi-layer cooling furnace (2), the flue gas passes through the inner layer platform (11) and the outer layer platform (12) from bottom to top in turn and exchanges heat with the heat exchange medium. The flue gas after cooling is discharged through the low-temperature flue gas pipe (23) of the multi-layer cooling furnace (2), and then discharged after dust removal by the dust removal device. The heat exchange medium after heating is discharged through the heat exchange medium outlet of the multi-layer cooling furnace (2); The heat exchange medium discharged from the heat exchange medium outlet of the multi-layer cooling furnace (2) is transported to the multi-layer heating furnace (3) through the first transport device and is fed into the furnace body (6) from the heat exchange medium inlet of the multi-layer cooling furnace (2). The heat exchange medium (16) gradually descends to the bottom of the multi-layer heating furnace (3) in the multi-layer heating furnace (3) in the same manner as the multi-layer cooling furnace (2). Normal temperature gas passes through the blower (28) and the normal temperature gas pipe (27) into the bottom of the multi-layer heating furnace (3). In the furnace body (6) of the multi-layer heating furnace (3), the gas passes through the inner layer platform (11) and the outer layer platform (12) of each layer from bottom to top and exchanges heat with the heat exchange medium. The heated gas is discharged through the heating gas pipe (29) of the multi-layer heating furnace (3). The cooled heat exchange medium is discharged through the heat exchange medium outlet of the multi-layer heating furnace (3). The heat exchange medium discharged from the heat exchange medium outlet of the multi-layer heating furnace (3) is returned to the multi-layer cooling furnace (2) through the second conveying device, and is fed into the furnace body (6) from the heat exchange medium inlet of the multi-layer cooling furnace (2) to perform heat exchange with the flue gas again.

8. A method for utilizing waste heat from a high-temperature flue gas multi-layer furnace according to claim 7, characterized in that: The heat exchange medium (16) is aluminum oxide-based or iron oxide-based solid particles, and the maximum particle size does not exceed 50 mm.

9. The method for utilizing waste heat from a high-temperature flue gas multi-layer furnace according to claim 8, characterized in that: The temperature of the flue gas entering the multi-layer cooling furnace (2) through the high-temperature flue gas pipe (1) is not less than 500° C., the temperature of the flue gas discharged through the low-temperature flue gas pipe (23) of the multi-layer cooling furnace (2) is not more than 200° C., and the temperature of the gas discharged through the heating gas pipe (29) of the multi-layer heating furnace (3) is not less than 400° C.

10. The method for utilizing waste heat from a high-temperature flue gas multi-layer furnace according to claim 8, characterized in that: The temperature of the heat exchange medium discharged from the heat exchange medium outlet of the multi-layer temperature-lowering furnace (2) is not less than 400° C., and the temperature of the heat exchange medium discharged from the heat exchange medium outlet of the multi-layer temperature-raising furnace (3) is not more than 200° C.; The residence time of the heat exchange medium (16) in the multi-layer cooling furnace (2) and the multi-layer heating furnace (3) is 15 to 60 minutes, and the time taken for the heat exchange medium (16) to complete one cycle through the multi-layer cooling furnace (2), the multi-layer heating furnace (3), the first conveying device, and the second conveying device is 40 to 140 minutes; the stacking thickness of the heat exchange medium (16) on the inner layer platform (11) and the outer layer platform (12) in the multi-layer cooling furnace (2) and the multi-layer heating furnace (3) does not exceed 100 mm.

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