A tunnel kiln based on high-temperature air combustion

Abstract

The present invention provides a tunnel kiln based on high-temperature air combustion, which includes a preheating zone, a firing zone, and a cooling zone connected in sequence. The kiln roofs of the low-temperature section of the cooling zone and the preheating zone are three-centered arch roofs, and the kiln roofs of the medium-temperature section of the cooling zone and the firing zone are three-centered double-layer arch roofs with an air interlayer inside; the kiln wall of the medium-temperature section of the cooling zone is provided with cold air suction vents, and there is an air inlet channel between the cold air suction vents and the air interlayer. The kiln wall of the firing zone is provided with a plurality of high-temperature air combustion components, and each high-temperature air combustion component includes an injector and a burner; the kiln bottom of the low-temperature section of the preheating zone is provided with a hot air extraction channel at the kiln bottom, and the kiln bottom of the firing zone is provided with a cold air supply channel at the kiln bottom. The beneficial effects of the present invention are as follows: The waste heat of the cooling zone and the firing zone is used to heat the air in the air interlayer to form preheated combustion-supporting air at 800-1400°C, realizing high-temperature air combustion. The temperature of the preheated combustion-supporting air is high, the proportion of the preheated combustion-supporting air volume to the air required for the burner combustion is high, the fuel consumption is low, and the thermal efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel kiln equipment, and particularly to a tunnel kiln based on high-temperature air combustion. Background Art

[0002] A tunnel kiln is a thermal equipment for continuous countercurrent production, commonly used for sintering products such as bricks, tiles, ceramics, refractory materials, etc. It has the advantages of high mechanization and automation levels, large output, high production efficiency, high thermal efficiency, etc. Along the length direction, according to different functions of the tunnel kiln, it can be divided into a preheating zone, a firing zone, and a cooling zone. Green blanks are stacked on kiln cars and pushed into the kiln from the kiln head. First, they are preheated in the preheating zone, enter the firing zone to reach the highest firing temperature and be kept at a certain temperature for sintering the products, and then are cooled in the cooling zone to a low temperature and then pushed out from the kiln tail. The cold air introduced into the cooling zone exchanges heat with the products and then the temperature rises. Part of the excess hot air is extracted for drying, and the other part reaches the firing zone to further participate in combustion; the high-temperature flue gas in the firing zone flows towards the preheating zone, exchanges heat with the products, the flue gas temperature decreases, and is discharged through the smoke exhaust system near the kiln head.

[0003] Therefore, continuously burned products are fully heat-exchanged with the gas in the kiln. For intermittent kilns, due to the difficulty of directly using the waste heat during the intermittent production process, the energy consumption is high and the thermal efficiency is low. For example, Chinese Patent CN201820696670.5 discloses an energy-saving and environment-friendly crucible kiln. There are two sets of regenerative burners symmetrically arranged on both sides of the kiln wall of the furnace body. The two burners are respectively in the heat storage and heat release states, work alternately, and take turns to act as the roles of combustion and smoke exhaust, with relatively high energy consumption.

[0004] However, the current tunnel kilns have a low utilization efficiency of waste heat. The regenerative combustion technology adopted to achieve high-temperature air combustion is to preheat the regenerator with the high-temperature flue gas in the kiln, and then exchange the heat to the combustion-supporting air. Because the sensible heat brought by the combustion-supporting air is low, the heat is mainly provided by fuel, resulting in high energy consumption. For example, Chinese Invention Patent CN 202110815345.2 discloses a regenerative tunnel kiln with flue gas reflux and high-temperature section smoke exhaust and a roasting process, which also heats the combustion-supporting air by a regenerative heat exchanger with the high-temperature flue gas in the roasting section. Summary of the Invention

[0005] In view of this, in order to solve the problems of low temperature of the combustion-supporting air in the tunnel kiln and high energy consumption, an embodiment of the present invention provides a tunnel kiln based on high-temperature air combustion.

[0006] An embodiment of the present invention provides a tunnel kiln based on high-temperature air combustion, including a preheating zone, a firing zone, and a cooling zone connected in sequence;

[0007] The kiln top of the low-temperature section of the cooling zone and the preheating zone is a three-centered arch roof structure. The kiln top of the medium-temperature section of the cooling zone and the firing zone is a three-centered double-layer arch roof structure. An air interlayer is provided inside the three-centered double-layer arch roof structure. And a hot air channel is provided above the air interlayer of the kiln top in the medium-temperature section of the cooling zone and the firing zone, which communicates with the air interlayer in the medium-temperature section area of the cooling zone and the air interlayer in the firing zone area to suck the air in the air interlayer in the medium-temperature section area of the cooling zone to the firing zone area;

[0008] The kiln wall of the medium-temperature section of the cooling zone is provided with cold air suction openings. An air inlet channel is provided between the cold air suction openings and the air interlayer. The kiln wall of the firing zone is provided with a plurality of high-temperature air combustion assemblies. Each high-temperature air combustion assembly includes an injector and a burner. Wherein the injector includes an air inlet channel and an air suction channel. The air inlet channel includes a Laval nozzle. The upper end of the Laval nozzle is used for inputting air, and the lower end extends to the air interlayer in the firing zone area. The air suction channel includes a Venturi channel. The upper end of the Venturi channel extends into the air interlayer. The lower end of the Laval nozzle is arranged opposite to the upper end of the Venturi channel. And the diameter of the upper end of the Venturi channel is larger than the diameter of the lower end of the Laval nozzle. The air suction channel is connected to the burner;

[0009] The kiln bottom of the low-temperature section of the preheating zone is provided with a hot air extraction channel at the kiln bottom. The kiln bottom of the firing zone is provided with a cold air supply channel at the kiln bottom.

[0010] Further, the Laval nozzle includes a nozzle and a working fluid channel connected to the lower end of the nozzle. The diameter of the nozzle gradually increases from bottom to top. The diameter of the working fluid channel gradually increases from top to bottom.

[0011] Further, the air inlet channel further includes an air intake nozzle. The upper end of the air intake nozzle extends out of the firing zone, and the lower end is connected to the upper end of the nozzle.

[0012] Further, the Venturi channel includes a mixing chamber, a throat channel and a diffuser chamber connected in sequence from top to bottom. The diameter of the mixing chamber gradually increases from bottom to top. The throat channel is a straight pipe section. The diameter of the diffuser chamber gradually increases from top to bottom. The upper end of the mixing chamber is arranged opposite to the lower end of the working fluid channel.

[0013] Further, each high-temperature air combustion assembly further includes an air supply channel. The air supply channel is connected to the lower end of the diffuser chamber and the burner.

[0014] Further, the burner includes an inner channel, an outer channel disposed around the inner channel, and a plurality of air supply and combustion assisting hot air channels, wherein the inner channel is used for inputting air, the outer channel is used for inputting fuel, and each of the air supply and combustion assisting hot air channels is connected to the air supply channel.

[0015] Further, the air supply channel includes a vertical air supply channel, a horizontal air supply channel, and two extended air supply channels. The upper end of the vertical air supply channel is connected to the lower end of the diffusion chamber, and the lower end is connected to the horizontal air supply channel. The horizontal air supply channel is arranged along the length direction of the firing zone. The burner vertically penetrates through the horizontal air supply channel, such that the rear ends of some of the air supply and combustion assisting hot air channels extend into the horizontal air supply channel. The two extended air supply channels respectively extend along the upper and lower sides of the burner and communicate with the horizontal air supply channel, and the rear ends of the other parts of the air supply and combustion assisting hot air channels respectively extend into the two extended air supply channels.

[0016] Further, the burner further includes a mixing channel, which includes a conical channel and a horizontal channel. The smaller diameter end of the conical channel is respectively connected to the inner channel, the outer channel, and each of the air supply and combustion assisting hot air channels, and the larger diameter end of the conical channel is connected to one end of the horizontal channel. The other end of the horizontal channel extends to the inner side of the firing zone.

[0017] Further, the central angle of the arch corresponding to the air interlayer is 60°.

[0018] Further, the region where the air interlayer is located in the cooling zone is the interval of 650°C to 1000°C when the cooling zone is working.

[0019] The beneficial effects brought by the technical solution provided by the embodiment of the present invention are as follows:

[0020] 1. For a tunnel kiln based on high-temperature air combustion according to the present invention, the waste heat of the cooling zone and the firing zone is used to heat the air in the air interlayer to form preheated combustion-supporting air at 800 - 1400°C. The preheated combustion-supporting air is accelerated and injected into the burner through the Laval nozzle and the Venturi channel of the injector, realizing high-temperature air combustion. The preheated combustion-supporting air has a high temperature, and the proportion of the preheated combustion-supporting air volume in the air required for the burner combustion is high, with low fuel consumption and improved thermal efficiency.

[0021] 2. For a tunnel kiln based on high-temperature air combustion according to the present invention, a three-centered arch roof structure is adopted, with zero lateral thrust, which can minimize the lateral deformation of the kiln body to the greatest extent and improve the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the plane layout diagram of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0023] Figure 2It is a schematic structural view of the preheating zone and the low-temperature zone of the cooling zone of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0024] Figure 3 It is a schematic structural view of the firing zone of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0025] Figure 4 It is a schematic view of the kiln roof structure of the middle-temperature zone of the cooling zone of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0026] Figure 5 It is a schematic view of the structure of one side of the kiln wall of the cooling zone of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0027] Figure 6 It is an axial partial sectional view of the firing zone of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0028] Figure 7 It is a radial partial sectional view of the firing zone of a tunnel kiln based on high-temperature air combustion according to the present invention;

[0029] Figure 8 It is a schematic installation view of a burner;

[0030] Figure 9 It is a schematic view of a burner.

[0031] In the figure: 1 - kiln wall, 2 - arch roof, 3 - air interlayer, 4 - air inlet channel, 5 - hot air supply channel, 6 - air inlet nozzle, 7 - Laval nozzle, 8 - nozzle, 9 - working fluid channel, 10 - entrained fluid channel, 11 - air suction channel, 12 - mixing chamber, 13 - throat channel, 14 - diffuser chamber, 15 - vertical air supply channel, 16 - horizontal air supply channel, 17 - cold air suction opening, 18 - damper, 19 - air entry channel, 20 - ejector, 21 - burner, 22 - extended air supply channel, 23 - inner channel, 24 - outer channel, 25 - auxiliary combustion hot air supply channel, 26 - conical channel, 27 - horizontal channel. Detailed implementation manners

[0032] To make the purpose, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the drawings. The following describes a relatively superior one among multiple possible embodiments of the present invention, aiming to provide a basic understanding of the present invention, but not aiming to identify the key or decisive elements of the present invention or limit the scope to be protected.

[0033] In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0034] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices shall be regarded as part of the authorization specification.

[0035] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. At the same time, it should be understood that for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships.

[0036] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0037] Please refer to Figures 1 to 9 , an embodiment of the present invention provides a tunnel kiln based on high-temperature air combustion, including three sections of kiln bodies: a preheating zone T1, a firing zone T2, and a cooling zone T3, which are connected in sequence. Among them, the preheating zone T1 includes a low-temperature section T101 and a medium-temperature section T102 of the preheating zone, and the cooling zone T3 includes a low-temperature section T301 and a medium-temperature section T302 of the cooling zone.

[0038] As Figure 1 and 2 shown, each section of the kiln body includes a kiln roof in the middle, two kiln walls 1 on both sides of the kiln roof, and a kiln bottom at the bottom.

[0039] Kiln roof structure:

[0040] Continuing as Figure 2 shown, the kiln roofs of the low-temperature section T301 of the cooling zone and the preheating zone T1 are three-centered arch roof structures. Specifically, the three-centered arch roof structure includes two layers of arch roofs 2 that are fitted together. Each layer of the arch roof 2 includes a middle arch and two side arches arranged on both sides of the middle arch. As described in this embodiment, the central angle of the middle arch is 60°, and the central angles of the side arches are also 60°. The radius R2 of the middle arch is 1500 - 2500 mm, and the radii R1 and R3 of the side arches are both 200 - 400 mm.

[0041] And the kiln roof of the firing zone T2 is a three-centered double-layer arch roof structure as Figure 3 shown, and at the same time, the kiln roof of the medium-temperature section T302 of the cooling zone is as Figure 4The shown three-centered double-layer vault structure, and an air interlayer 3 is provided inside the three-centered double-layer vault structure. Specifically, the three-centered double-layer vault structure includes three layers of vaults 2 stacked in sequence from top to bottom, and a notch is provided in the middle of the vault 2 in the middle layer, so that the space between the two layers of vaults 2 above and below forms the air interlayer 3.

[0042] The air interlayer 3 is located in the firing zone T2 interval and the medium-temperature section T302 interval during the operation of the cooling zone. As in this embodiment, the area where the air interlayer 3 is located in the medium-temperature section T302 of the cooling zone is the interval of 650°C to 1000°C during the operation of the cooling zone T3, so as to ensure that the air interlayer 3 is located in a region with a higher temperature to improve the heat exchange efficiency.

[0043] A hot air channel is provided above the air interlayer of the kiln roof in the medium-temperature section T302 of the cooling zone and the firing zone T2, which connects the air interlayer 3 in the medium-temperature section T302 region of the cooling zone and the air interlayer 3 in the firing zone T2 region, so as to suck the air in the air interlayer 3 in the medium-temperature section T302 region of the cooling zone to the firing zone T2 region. Specifically, the hot air channel connects the air interlayer 3 at one end of the cooling zone and the air interlayer 3 at one end of the firing zone. Specifically, an air suction hot air channel communicating with the air interlayer 3 is provided on the kiln roof of the cooling zone, and a hot air supply channel 5 communicating with the air interlayer 3 is provided on the kiln roof of the firing zone, and the hot air channel connects the air suction hot air channel and the hot air supply channel 5.

[0044] Kiln wall structure:

[0045] The kiln wall in the medium-temperature section T302 of the cooling zone is provided with cold air suction openings 17, and an air inlet channel 19 is provided between the cold air suction openings 17 and the air interlayer 3, so that cold air enters the medium-temperature zone T302 region of the air interlayer 3 in the cooling zone. As Figure 5 shown, in this embodiment, the cold air suction openings 17 are specifically arranged at the lower part of the kiln wall 1 of the cooling zone, and an air inlet channel 19 is provided between the cold air suction openings 17 and the air interlayer 3. As in this embodiment, the air inlet channel 19 is a vertical channel and communicates with the air interlayer 3. A shutter 18 can also be installed at the cold air suction openings 17 for adjusting the air suction volume of the air inlet channel 19.

[0046] Regarding the number of the cold air suction openings 17, it can be flexibly set to multiple pairs according to the actual application scenario, such as 3 to 5 pairs. Each pair of the cold air suction openings 17 is symmetrically arranged on the two kiln walls 1 of the cooling zone, and the multiple cold air suction openings 17 on one kiln wall 1 are evenly distributed along the length direction of the kiln wall 1.

[0047] The kiln wall of the firing zone T2 is provided with a plurality of high-temperature air combustion components. As Figure 3 and 6 shown, the function of the high-temperature air combustion components is to burn fuel to heat the blanks on the kiln car. The number of the high-temperature air combustion components can be set to multiple pairs according to actual needs, such as 9 - 30 pairs. Each pair of the high-temperature air combustion components is symmetrically arranged on both sides of the firing zone. 1 - 2 pairs are arranged at the parking space A of each kiln car.

[0048] As Figure 6 and Figure 7 shown, each of the high-temperature air combustion components includes an injector 20, an air supply channel, and a burner 21. The injector 20 is used to input the preheated combustion-supporting air in the air interlayer 3 of the firing zone into the burner 21 via the air supply channel. The injector 20 includes an air inlet channel 4 and an air suction channel 11. The air inlet channel 4 and the air suction channel 11 are both vertically arranged in the kiln wall 1 of the firing zone and are coaxially arranged.

[0049] The air inlet channel 4 includes a Laval nozzle 7 and an air inlet nozzle 6. The air inlet nozzle 6 is vertically arranged in the kiln wall 1 of the firing zone. The upper end of the air inlet nozzle 6 extends out of the kiln wall 1 of the firing zone and is connected to an external gas pipeline. Normal temperature air is input into the Laval nozzle 7 from the air inlet nozzle 6.

[0050] The lower end of the Laval nozzle 7 is arranged opposite to the upper end of the air suction channel 11. The Laval nozzle 7 includes a nozzle 8 and a working fluid channel 9 connected to the lower end of the nozzle 8. The diameter of the nozzle 8 gradually increases from bottom to top, and the diameter of the working fluid channel 9 gradually increases from top to bottom. The upper end of the nozzle 8 is connected to the lower end of the air inlet nozzle 6, and the lower end of the working fluid channel 9 extends into the air interlayer 3. Here, the air interlayer 3 is provided with an ejector fluid channel 10 extending below the working fluid channel 9.

[0051] The air suction channel 11 includes a Venturi channel. The Venturi channel includes a mixing chamber 12, a throat channel 13, and a diffuser chamber 14 connected in sequence from top to bottom. The diameter of the mixing chamber 12 gradually increases from bottom to top. The throat channel 13 is a straight pipe section. The diameter of the diffuser chamber 14 gradually increases from top to bottom. The upper end of the mixing chamber 12 extends into the air interlayer 3 and is arranged opposite to the lower end of the working fluid channel 9. Preferably, the diameter of the upper end of the Venturi channel is larger than the diameter of the lower end of the Laval nozzle 7.

[0052] The air supply channel connects the lower end of the diffusion chamber 14 and the burner 21, so as to convey preheated combustion-supporting air to the burner 21. Specifically, the air supply channel includes a vertical air supply channel 15, a horizontal air supply channel 16, and two extended air supply channels 22. The upper end of the vertical air supply channel 15 is connected to the lower end of the diffusion chamber 14, and the lower end is connected to the horizontal air supply channel 16. The horizontal air supply channel 15 is arranged along the length direction of the firing zone T2.

[0053] As Figure 8 and 9 shown, the burner 21 crosses the kiln wall of the firing zone T2 and is arranged at the same height as the table plane L of the kiln car. The burner 21 includes an inner channel 23, an outer channel 24 arranged around the inner channel 23, and a plurality of combustion-supporting hot air supply channels 25. The inner channel 23 is used for inputting air, the outer channel 24 is used for inputting fuel, and each combustion-supporting hot air supply channel 25 is connected to the extended air supply channel 22 of the air supply channel. As in this embodiment, the number of the combustion-supporting hot air supply channels 25 is four, which are evenly distributed around the axis of the burner 21. The rear end of each combustion-supporting hot air supply channel 25 is the air inlet end, and the preheated combustion-supporting air enters from the rear end of the combustion-supporting hot air supply channel 25.

[0054] As Figure 6 and 8 shown, the burner 21 vertically penetrates the horizontal air supply channel 16, so that the rear ends of some combustion-supporting hot air supply channels 25 extend into the horizontal air supply channel 16. As in this embodiment, the rear ends of the two horizontal combustion-supporting hot air supply channels 25 directly extend into the horizontal air supply channel 16. The two extended air supply channels 22 respectively extend along the upper and lower sides of the burner 21 and communicate with the horizontal air supply channel 16. The rear ends of the other part of the combustion-supporting hot air supply channels 25 respectively extend into the two extended air supply channels 22. As in this embodiment, the rear end of one combustion-supporting hot air supply channel 25 located above directly extends into the upper extended air supply channel 22, and the rear end of one combustion-supporting hot air supply channel 25 located below directly extends into the lower extended air supply channel 22.

[0055] The preheated combustion-supporting air flows into the horizontal air supply channel 16 through the vertical air supply channel 15. When the preheated combustion-supporting air flows in the horizontal air supply channel 16 to the burner, the preheated combustion-supporting air is respectively shunted upward and downward along the two extended air supply channels 22, so that the preheated combustion-supporting air can surround the burner 21. Furthermore, the preheated combustion-supporting air can flow into along the rear ends of the combustion-supporting hot air supply channels 25 and flow out along the front ends of the combustion-supporting hot air supply channels 25 and uniformly enter the burner 21.

[0056] As Figure 8 and 9As shown, the burner 21 further includes a mixing channel, which includes a conical channel 26 and a horizontal channel 27. One end with a smaller diameter of the conical channel 26 is respectively connected to the inner channel 23, the outer channel 24 and each of the combustion-supporting hot air supply channels 25. One end with a larger diameter of the conical channel 26 is connected to one end of the horizontal channel 27, and the other end of the horizontal channel 27 extends to the inner side of the firing zone.

[0057] The kiln wall of the cooling zone T3 is provided with a cooling air channel and an excess hot air extraction channel. The external cooling air system S6 is connected to the cooling air channel to introduce cold air into the kiln; the external excess hot air extraction system S7 is connected to the excess hot air extraction channel to extract the hot air in the kiln, accelerating the cooling of the fired products in the cooling zone T.

[0058] When the above-mentioned tunnel kiln based on high-temperature air combustion works:

[0059] The primary combustion-supporting cold air system S1 is connected to each cold air suction port 17. The primary combustion-supporting cold air system S1 extracts the external cold air and enters the air interlayer 3 through the cold air suction port 17 of the cooling zone T3. After the air enters the cooling zone, it is preliminarily heated by the waste heat in the cooling zone to form preheated air.

[0060] The combustion-supporting hot air extraction and supply system S2 is connected to the hot air channel. The preheated air is extracted to the air interlayer 3 in the firing zone and then is secondary-heated by the air interlayer 3, forming preheated combustion-supporting air in the area of the air interlayer 3 located in the firing zone. In this way, the temperature of the kiln roof in the firing zone is higher, and the temperature of the preheated combustion-supporting air is also higher, up to 800 - 1400 °C; at the same time, the waste heat recovery and utilization efficiency of the tunnel kiln can be improved, making it more energy-saving.

[0061] The fuel combustion system S3 is connected to the upper ends of the intake nozzles 6 of each of the high-temperature air combustion components to input air. The normal-temperature air input into the Laval nozzle 7 through the intake nozzle 6 is accelerated by the Laval nozzle 7 and then enters the air suction channel 11, and the preheated combustion-supporting air in the air interlayer in the firing zone is sucked into the air suction channel 11. The air suction channel 11 is of a Venturi structure to further increase the flow rate of the fluid, so that the preheated combustion-supporting air has sufficient power.

[0062] Subsequently, the preheated combustion-supporting air is input into the burner 21 along the vertical air supply channel 15, the horizontal air supply channel 16, and the two extended air supply channels. The preheated combustion-supporting air is respectively input into the conical channel 26 through the hot combustion-supporting air supply channel 25, the normal-temperature air is input into the conical channel 26 through the inner channel 23, and the fuel is input into the conical channel 26 through the outer channel 24. A large amount of preheated combustion-supporting air, a small amount of normal-temperature air, and the fuel are mixed in the conical channel 26 and then enter the interior of the firing zone through the horizontal channel 27 to achieve high-temperature air combustion. The proportion of the preheated combustion-supporting air in the combustion air can be as high as 80%.

[0063] Bottom structure of the kiln:

[0064] A hot air extraction channel is provided at the bottom of the kiln in the low-temperature section T101 of the preheating zone. Specifically, the hot air extraction channel is provided at 1 to 2 vehicle positions near the medium-temperature section 102 in the low-temperature section 101 of the preheating zone. The hot air extraction channel includes a vertical hot air extraction channel and a horizontal hot air extraction channel. Both the vertical hot air extraction channel and the horizontal hot air extraction channel are provided with a plurality of upward hot air extraction openings, and each hot air extraction opening is flush with the lower plane of the track in the kiln. The external bottom hot air extraction system S4 is connected to the hot air extraction channel, and the hot air is sent to other places that need heating, such as a drying kiln, through the hot air extraction channel, so as to better save energy and reduce costs.

[0065] A cold air supply channel is provided at the bottom of the kiln in the firing zone T2. The cold air supply channel is provided at 3 to 5 vehicle positions near the medium-temperature section of the cooling zone in the firing zone T2. The cold air supply channel includes a vertical cold air supply channel and a horizontal cold air supply channel. Both the vertical cold air supply channel and the horizontal cold air supply channel are provided with a plurality of upward cold air supply openings, and each cold air supply opening is flush with the lower plane of the track in the kiln. The external bottom air supply system S5 is connected to the cold air supply channel, and cold air is conveyed to the bottom of the kiln car through the cold air supply channel to cool the kiln car and ensure that the temperature at the bottom of the kiln does not become too high.

[0066] In this article, the orientation words such as front, back, up, and down are defined based on the positions of the components in the drawings and the positions of the components relative to each other, only for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different usage and placement methods. The use of the orientation words should not limit the scope of protection requested by this application.

[0067] Without conflict, the above-mentioned embodiments and the features in the embodiments in this article can be combined with each other.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tunnel kiln based on high-temperature air combustion, comprising a preheating zone, a firing zone and a cooling zone connected in sequence, characterized in that: The kiln top of the low-temperature section of the cooling zone and the preheating zone is a three-centered arch roof structure, and the kiln top of the medium-temperature section of the cooling zone and the firing zone is a three-centered double-layer arch roof structure. An air interlayer is provided inside the three-centered double-layer arch roof structure, and a hot air channel is provided above the air interlayer of the kiln top in the medium-temperature section of the cooling zone and the firing zone, which communicates with the air interlayer in the medium-temperature section area of the cooling zone and the air interlayer in the firing zone area to suck the air in the air interlayer in the medium-temperature section area of the cooling zone to the firing zone area; The kiln wall of the medium-temperature section of the cooling zone is provided with cold air suction openings, and an air inlet channel is provided between the cold air suction openings and the air interlayer. The kiln wall of the firing zone is provided with a plurality of high-temperature air combustion assemblies. Each high-temperature air combustion assembly includes an injector and a burner. The injector includes an air inlet channel and an air suction channel. The air inlet channel includes a Laval nozzle. The upper end of the Laval nozzle is used to input air, and the lower end extends to the air interlayer in the firing zone area. The air suction channel includes a Venturi channel. The upper end of the Venturi channel extends into the air interlayer. The lower end of the Laval nozzle is arranged opposite to the upper end of the Venturi channel, and the diameter of the upper end of the Venturi channel is larger than the diameter of the lower end of the Laval nozzle. The air suction channel is connected to the burner; The kiln bottom of the low-temperature section of the preheating zone is provided with a hot air suction channel at the kiln bottom, and the kiln bottom of the firing zone is provided with a cold air supply channel at the kiln bottom.

2. The tunnel kiln based on high-temperature air combustion according to claim 1, wherein: The Laval nozzle includes a nozzle and a working fluid channel connected to the lower end of the nozzle. The diameter of the nozzle gradually increases from bottom to top, and the diameter of the working fluid channel gradually increases from top to bottom.

3. The tunnel kiln based on high-temperature air combustion according to claim 2, wherein: The air inlet channel further includes an air inlet nozzle. The upper end of the air inlet nozzle extends out of the firing zone, and the lower end is connected to the upper end of the nozzle.

4. A tunnel kiln based on high-temperature air combustion according to claim 2, characterized in that: The Venturi channel includes a mixing chamber, a throat channel and a diffuser chamber connected in sequence from top to bottom. The diameter of the mixing chamber gradually increases from bottom to top. The throat channel is a straight pipe section. The diameter of the diffuser chamber gradually increases from top to bottom. The upper end of the mixing chamber is arranged opposite to the lower end of the working fluid channel.

5. The tunnel kiln based on high-temperature air combustion according to claim 4, characterized in that: Each high-temperature air combustion assembly further includes an air supply channel, and the air supply channel is connected to the lower end of the diffuser chamber and the burner.

6. The tunnel kiln based on high-temperature air combustion according to claim 5, wherein: The burner includes an inner channel, an outer channel arranged around the inner channel, and a plurality of auxiliary combustion hot air supply channels. The inner channel is used to input air, the outer channel is used to input fuel, and each auxiliary combustion hot air supply channel is connected to the air supply channel.

7. The tunnel kiln based on high-temperature air combustion according to claim 6, characterized in that: The air supply passage includes a vertical air supply passage, a horizontal air supply passage and two extended air supply passages. The upper end of the vertical air supply passage is connected to the lower end of the diffusion chamber, and the lower end is connected to the horizontal air supply passage. The horizontal air supply passage is arranged along the length direction of the firing zone. The burner vertically penetrates the horizontal air supply passage, so that the rear end of a part of the auxiliary combustion hot air supply passage extends into the horizontal air supply passage. The two extended air supply passages respectively extend along the upper and lower sides of the burner and communicate with the horizontal air supply passage, and the rear ends of the other parts of the auxiliary combustion hot air supply passages respectively extend into the two extended air supply passages.

8. A tunnel kiln based on high-temperature air combustion according to claim 6, characterized in that: The burner further includes a mixing passage, and the mixing passage includes a conical passage and a horizontal passage. The smaller diameter end of the conical passage is respectively connected to the inner passage, the outer passage and each of the auxiliary combustion hot air supply passages, the larger diameter end of the conical passage is connected to one end of the horizontal passage, and the other end of the horizontal passage extends to the inner side surface of the firing zone.

9. A tunnel kiln based on high-temperature air combustion according to claim 1, characterized in that: The arch central angle corresponding to the air interlayer is 60°.

10. A tunnel kiln based on high-temperature air combustion according to claim 1, characterized in that: The region where the air interlayer is located in the cooling zone is the interval of 650°C to 1000°C when the cooling zone is working.

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