A vertical tunnel thermal storage oxidation device

Abstract

The invention relates to the technical field of environmental protection equipment, and specifically discloses a vertical tunnel regenerative thermal oxidation device, which comprises a preheating chamber, a combustion chamber, a first combustion chamber and a second combustion chamber which are connected in sequence, wherein a first constriction section is provided between the first combustion chamber and the second combustion chamber, and a flow cross-sectional area of ​​the first constriction section is smaller than any one of a flow cross-sectional area of ​​the first combustion chamber and a flow cross-sectional area of ​​the second combustion chamber; in the above scheme, the design of the first constriction section can increase the flow velocity of the exhaust gas when passing through the first constriction section, so that the relative motion velocity between the exhaust gas molecules will also increase, thereby causing the collision and friction between the exhaust gas molecules to intensify, and the friction between the exhaust gas molecules will convert part of the kinetic energy into heat energy, so that the temperature of the exhaust gas rises, which is helpful to promote the further oxidation and decomposition of the organic matter that is not completely burned in the combustion reaction, thereby improving the combustion efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection equipment, and in particular to a vertical tunnel thermal storage oxidation device. Background Art

[0002] At present, most of the waste gas generated by the impregnation machine in the copper clad laminate industry is treated by incineration equipment. The regenerative combustion furnace is a highly efficient waste gas treatment equipment, mainly used to treat industrial waste gas containing volatile organic compounds. It uses a specific heat recovery technology to heat the waste gas to a sufficiently high temperature, so that the organic matter in the waste gas is oxidized and decomposed into non-toxic and harmless carbon dioxide and water at high temperature.

[0003] In the related technology, the regenerative heat combustion furnace has the problem of incomplete combustion during use, resulting in the failure to completely convert harmful substances in the exhaust gas into harmless substances, reducing the treatment effect of the regenerative heat combustion furnace, and part of the fuel is not completely converted into thermal energy, which increases energy consumption and operating costs. There is also a risk of environmental pollution. Summary of the invention

[0004] The invention discloses a vertical tunnel regenerative thermal oxidation device to solve the technical problem of low combustion efficiency in the regenerative combustion furnace in the related art.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] The present application provides a vertical tunnel regenerative thermal oxidation device, which includes a preheating chamber, a combustion chamber, a first burnout chamber and a second burnout chamber connected in sequence, wherein a first tapered section is provided between the first burnout chamber and the second burnout chamber, and a flow cross-sectional area of ​​the first tapered section is smaller than any one of a flow cross-sectional area of ​​the first burnout chamber and a flow cross-sectional area of ​​the second burnout chamber.

[0007] Furthermore, a guide portion is provided between the first combustion chamber and the first constricted section, and along the flow direction of the exhaust gas, the flow cross-sectional area of ​​the guide portion gradually decreases, and the small end of the guide portion is connected to the first constricted section.

[0008] Furthermore, the guide portion has a guide surface inclined relative to the flow direction of the exhaust gas, the angle between the guide surface and the first direction is α, 45°≤α≤75°, and the first direction is opposite to the flow direction of the exhaust gas.

[0009] Furthermore, a second tapered section is provided between the preheating chamber and the combustion chamber, and a flow cross-sectional area of ​​the second tapered section is smaller than any one of the flow cross-sectional area of ​​the preheating chamber and the flow cross-sectional area of ​​the combustion chamber.

[0010] Furthermore, a flow balancing plate is provided between the combustion chamber and the first combustion chamber, and a plurality of flow balancing holes are provided on the flow balancing plate.

[0011] Furthermore, the diameter of the flow balancing holes located in the middle of the flow balancing plate is smaller than the diameter of the flow balancing holes located at the edge of the flow balancing plate.

[0012] Furthermore, a flow cross-sectional area of ​​the second necking section is larger than a flow cross-sectional area of ​​the first necking section, and along the flow direction of the exhaust gas, an extension length of the second necking section is smaller than an extension length of the first necking section.

[0013] Further, the preheating chamber, the combustion chamber, the first burnout chamber and the second burnout chamber are arranged upward in a longitudinal direction.

[0014] Furthermore, the vertical tunnel thermal storage oxidation device also includes a thermal storage body, and the thermal storage body is arranged in the air outlet duct of the second combustion chamber.

[0015] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0016] The vertical tunnel thermal storage oxidation device of the present application adds a first contraction section with a flow cross-sectional area smaller than that of the first combustion chamber and the second combustion chamber in the first combustion chamber and the second combustion chamber. The design of the first contraction section can increase the flow rate of the exhaust gas when passing through, so that the relative movement speed between the exhaust gas molecules will also increase, thereby causing the collision and friction between the exhaust gas molecules to intensify. The friction between the exhaust gas molecules will convert part of the kinetic energy into heat energy, so that the harmful substances that have not been fully decomposed and removed in the combustion chamber and the first combustion chamber can continue to be further decomposed in the second combustion chamber after the temperature of the first contraction section is raised, thereby improving the combustion efficiency and thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic structural diagram of a vertical tunnel thermal storage oxidation device according to an embodiment of the present application;

[0019] Figure 2 yes Figure 1 A local enlarged schematic diagram of the middle A;

[0020] Figure 3 is a top view of a vertical tunnel thermal storage oxidation device according to an embodiment of the present application;

[0021] Figure 4 It is a schematic diagram of the structure of the current equalizing plate of an embodiment of the present application.

[0022] In the figure:

[0023] 100, preheating chamber; 200, combustion chamber; 300, first combustion chamber; 310, guide portion; 311, guide surface; 400, second combustion chamber; 410, air outlet duct; 500, first constricted section; 600, flow balancing plate; 610, flow balancing hole; 700, second constricted section; 800, heat storage body; 900, explosion-proof device. DETAILED DESCRIPTION

[0024] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0025] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0026] The following is combined with Figure 1~Figure 4 , the vertical tunnel thermal storage oxidation device provided in the embodiment of the present application is described in detail through specific embodiments and their application scenarios.

[0027] See also Figure 1~Figure 3The present application provides a vertical tunnel regenerative oxidation device. The disclosed vertical tunnel regenerative oxidation device includes a preheating chamber 100, a combustion chamber 200, a first combustion chamber 300 and a second combustion chamber 400 which are connected in sequence. The waste gas generated in the production process first enters the preheating chamber 100. The preheating chamber 100 is mainly used for preheating the waste gas to increase the temperature of the waste gas. Exemplarily, a burner is arranged in the preheating chamber 100. The fuel and air are mixed and ignited by the burner to generate high-temperature and high-pressure combustion gas to release heat energy, thereby preheating the waste gas and air entering the furnace body. The combustion chamber 200 is used to burn the preheated waste gas and convert combustible components such as organic matter in the waste gas into harmless substances. For example, a burner is provided in the combustion chamber 200. The burner in the combustion chamber 200 can play an ignition role, so that the waste gas in the combustion chamber 200 burns and generates heat energy, and can ignite the fuel to burn when the waste gas concentration in the combustion chamber 200 is low, so as to ensure the temperature in the combustion chamber 200. After the combustion in the combustion chamber 200, most of the waste gas is completely burned in the combustion chamber 200, and the burned waste gas enters the first combustion chamber 300 and the second combustion chamber 400. The first combustion chamber 300 and the second combustion chamber 400 can prolong the residence time of the waste gas in the entire oxidation device to ensure that the incompletely burned combustible substances in the waste gas are fully burned.

[0028] In the embodiment of the present application, the vertical tunnel regenerative thermal oxidation device further includes a first constricted section 500, which is disposed between the first combustion chamber 300 and the second combustion chamber 400. Along the flow direction of the exhaust gas, the flow cross-sectional area of ​​the first constricted section 500 is smaller than the flow cross-sectional area of ​​the first combustion chamber 300. At the same time, the flow cross-sectional area of ​​the first constricted section 500 is also smaller than the flow cross-sectional area of ​​the second combustion chamber 400. In other words, the first constricted section 500 forms a neck structure between the first combustion chamber 300 and the second combustion chamber 400. The design of the first constricted section 500 reduces the flow cross-sectional area, so that the flow rate of the exhaust gas increases when the exhaust gas passes through the first constricted section 500.

[0029] Based on the above technical solution, on the one hand, the increase in the flow rate of the exhaust gas increases the relative movement speed between the exhaust gas molecules, thereby causing the collision and friction between the exhaust gas molecules to intensify. The friction between the exhaust gas molecules will convert part of the kinetic energy into thermal energy, causing the temperature of the exhaust gas to rise, which helps to promote further oxidation and decomposition of the incompletely burned organic matter in the combustion chamber 200 and the first combustion chamber 300, that is, it can make the incompletely burned organic matter burn fully after the temperature rises; on the other hand, the design of the first constricted section 500 can increase the turbulent kinetic energy of the exhaust gas when it passes through, which is beneficial to the full mixing of the exhaust gas and the air in the second combustion chamber 400, further ensuring full combustion and improving combustion efficiency.

[0030] In the optional embodiments of this application, please continue to refer to Figure 1~Figure 2 A guide portion 310 is provided between the first combustion chamber 300 and the first constricted section 500. Along the flow direction of the exhaust gas, the flow cross-sectional area of ​​the guide portion 310 gradually decreases, and the small end of the guide portion 310 is connected to the first constricted section 500. For example, the guide channel of the guide portion 310 may be a conical guide channel. By providing the guide portion 310 between the first combustion chamber 300 and the first constricted section 500, the guide portion 310 can guide the exhaust gas to form a circular flow while guiding the flow of the exhaust gas, increase the friction between the exhaust gas molecules, and enable the exhaust gas to heat up rapidly; on the other hand, based on the guiding effect of the guide portion 310 on the exhaust gas, it is possible to avoid the exhaust gas from forming a dead zone on the side of the first combustion chamber 300 close to the first constricted section 500, so that the exhaust gas in the first combustion chamber 300 can participate in the combustion and decomposition as fully as possible, thereby improving the combustion efficiency and the exhaust gas treatment efficiency.

[0031] In the examples of this application, see Figure 2 The guide portion 310 has a guide surface 311 which is inclined relative to the flow direction of the exhaust gas. The angle between the guide surface 311 and the first direction is α, and the first direction is opposite to the flow direction of the exhaust gas. In a further technical solution, 45°≤α≤75°, so that the guide surface 311 can guide the exhaust gas in the first combustion chamber 300 to enter the first constricted section 500, and at the same time, based on 45°≤α≤75°, the exhaust gas guided by the guide surface 311 is mainly used to generate circulation, that is, the guide surface 311 uses this inclination angle to make the friction heating effect between the exhaust gas molecules more obvious, thereby ensuring the combustion efficiency and thermal efficiency of the organic molecules in the exhaust gas, and the more obvious the circulation effect of the exhaust gas at the guide portion 310, the more evenly the exhaust gas molecules can be mixed with the air, the contact area between the organic molecules and the air can be increased, and the combustion efficiency can be further improved.

[0032] In the examples of this application, see Figure 1 A second constricted section 700 is provided between the preheating chamber 100 and the combustion chamber 200. The flow cross-sectional area of ​​the second constricted section 700 is smaller than the flow cross-sectional area of ​​the preheating chamber 100. At the same time, the flow cross-sectional area of ​​the second constricted section 700 is also smaller than the flow cross-sectional area of ​​the combustion chamber 200. Similarly, the flow velocity of the exhaust gas increases when passing through the second constricted section 700, thereby causing the collision and friction between the exhaust gas molecules to intensify. The friction between the exhaust gas molecules will convert part of the kinetic energy into heat energy, thereby improving the preheating effect of the preheating chamber 100 on the exhaust gas. At the same time, the design of the second constricted section 700 can form a squeeze flow toward the combustion chamber 200, which can enhance the mixing and flow of the exhaust gas and air in the combustion chamber 200, and improve the combustion efficiency of the organic molecules.

[0033] In the optional embodiments of this application, see Figure 1The vertical tunnel regenerative oxidation device of the embodiment of the present application may also include an explosion-proof device 900, which is arranged at the top of the second combustion chamber 400. For example, the explosion-proof device 900 may be a pressure-release explosion-proof device. The explosion-proof device 900 is arranged at the top of the second combustion chamber 400, that is, the explosion-proof device 900 is arranged at the end of the main flow direction (from bottom to top) of the exhaust gas in the entire oxidation device. In this way, when the pressure in the furnace of the entire oxidation device exceeds the safety pressure, the excessive positive pressure in the furnace will quickly open the explosion-proof device and release the pressure, which is conducive to the rapid release of pressure and avoids the movement of exhaust gas in the furnace.

[0034] In the optional embodiments of this application, please continue to refer to Figure 1 , Figure 2 and Figure 3 The vertical tunnel regenerative thermal oxidation device of the embodiment of the present application may further include a flow equalizing plate 600, which is disposed between the combustion chamber 200 and the first combustion chamber 300. The flow equalizing plate 600 is provided with a plurality of flow equalizing holes 610, and the flue gas generated by the combustion in the combustion chamber 200 is introduced into the first combustion chamber 300 through the flow equalizing holes 610. Exemplarily, the flow equalizing plate 600 may be formed by integral casting of a high temperature resistant material. Based on the flow guiding effect of the flow equalizing plate 600, the flue gas generated by the combustion chamber 200 can be evenly dispersed into the first combustion chamber 300, ensuring that the fluid flow rate in each area of ​​the first combustion chamber 300 is substantially the same, and the situation that the local area in the first combustion chamber 300 is overheated or the temperature in the local area is insufficient can be avoided, which helps to form a uniform temperature distribution in the first combustion chamber 300.

[0035] A flow equalizer plate 600 is provided at the end of the combustion chamber 200. The flow equalizer plate 600 can also ensure that the incompletely burned exhaust gas is fully mixed with the air, thereby reducing the generation of unburned substances and harmful gases while improving the combustion efficiency. At the same time, based on the flow equalizer hole 610 provided on the flow equalizer plate 600, the flow cross-sectional area at the end of the combustion chamber 200 can be further reduced, thereby keeping as much heat energy as possible in the combustion chamber 200, thereby further ensuring the sufficiency of combustion in the combustion chamber 200.

[0036] The inventors discovered during the research process that, due to the existence of the aforementioned second tapered section 700, the exhaust gas in the preheating chamber 100 mainly flows to the combustion chamber 200 through the middle thereof. As a result, the flow rate of the exhaust gas passing through the flow equalizing holes 610 in the middle of the flow equalizing plate 600 is significantly higher than the flow rate of the exhaust gas at the edge of the flow equalizing plate 600, resulting in the first combustion chamber 300 still having a problem of poor temperature uniformity.

[0037] Based on the above situation, in the optional embodiments of this application, please refer to Figure 4The aperture of the flow balancing hole 610 located in the middle of the flow balancing plate 600 is smaller than the aperture of the flow balancing hole 610 located at the edge of the flow balancing plate 600. In this way, compared with the flow balancing hole 610 in the middle of the flow balancing plate 600, by increasing the aperture of the flow balancing hole 610 at the edge of the flow balancing plate 600, the exhaust gas flow passing through the edge of the flow balancing plate 600 can be increased, so that the exhaust gas flow passing through the middle of the flow balancing plate 600 is equivalent to the exhaust gas flow passing through the edge of the flow balancing plate 600, thereby improving the flow distribution of the entire flow balancing plate 600 and improving the temperature uniformity of the first combustion chamber 300.

[0038] For further technical solutions, please continue to refer to Figure 1 , the flow cross-sectional area of ​​the second constricted section 700 is larger than the flow cross-sectional area of ​​the first constricted section 500. In this way, when the flow rate of the entire vertical tunnel thermal storage oxidation device remains unchanged, the flow rate of the exhaust gas entering the combustion chamber 200 through the second constricted section 700 is slower than the flow rate of the exhaust gas passing through the first constricted section 500, which can make the exhaust gas stay in the preheating chamber 100 for a longer time, thereby making the exhaust gas fully preheated in the preheating chamber 100, which can avoid the exhaust gas that is not fully preheated from having a low temperature when entering the combustion chamber 200 and reducing the combustion efficiency of the exhaust gas, and also avoid the exhaust gas that is not fully preheated from needing more energy in the combustion chamber 200 to be heated to a suitable temperature for combustion and causing energy waste, that is, this method can improve the combustion efficiency of the exhaust gas in the combustion chamber 200 while reducing energy consumption.

[0039] In a further technical solution, along the flow direction of the exhaust gas, the extension length of the second contraction section 700 is smaller than the extension length of the first contraction section 500. In this way, when the exhaust gas in the first combustion chamber 300 enters the second combustion chamber 400 through the first contraction section 500, the exhaust gas molecules have sufficient friction contact in an area with a smaller flow cross-sectional area. In addition, due to the longer extension length of the second contraction section 700, the exhaust gas molecules passing through the second contraction section 700 have sufficient time to heat up by friction, that is, the exhaust gas discharged from the first combustion chamber 300 enters the second combustion chamber 400 after being fully heated and accelerated, which helps to enhance the mixing and flow of the exhaust gas in the second combustion chamber 400, reduce incomplete combustion products, and help reduce overall energy consumption while further improving combustion efficiency.

[0040] In the embodiment of the present application, the preheating chamber 100, the combustion chamber 200, the first combustion chamber 300 and the second combustion chamber 400 are arranged upward in the longitudinal direction. On the one hand, the longitudinal arrangement improves the utilization rate of the longitudinal space and effectively reduces the land occupancy rate. On the other hand, the longitudinal arrangement helps to optimize the airflow flow, ensure that the flue gas flows smoothly between the preheating chamber 100, the combustion chamber 200, the first combustion chamber 300 and the second combustion chamber 400, reduce the resistance to the exhaust gas, that is, the wind resistance is low, which is conducive to improving the combustion efficiency.

[0041] Based on the aforementioned longitudinal arrangement, the longitudinal flow of exhaust gas can flush the heating surface of the entire vertical tunnel thermal storage oxidation device, which is conducive to the natural sedimentation of dust and particulate matter and reduces accumulation inside the equipment. In other words, the longitudinal arrangement is less prone to dust accumulation than the horizontal arrangement, which is conducive to extending the service life of the entire device.

[0042] The inventors also found during the research that during the flue gas combustion process, there is still a temperature difference between the preheating chamber 100, the combustion chamber 200, the first combustion chamber 300 and the second combustion chamber 400. In particular, the temperature difference is large before and after the entire device is started, which will cause a large thermal expansion of the entire device. If the regenerative thermal oxidation device is arranged horizontally, the lateral size of the entire oxidation device is large, and the deformation caused by thermal expansion will be transmitted to the lateral ends of the entire device, which is easy to cause damage to the equipment.

[0043] The thermal storage oxidation device in the embodiment of the present application is arranged longitudinally. When thermal expansion occurs, the entire device deforms upward. The lateral dimension of the part close to the ground is smaller, and the corresponding lateral deformation is also smaller, thereby reducing the thermal stress of the entire device and extending the service life of the equipment.

[0044] In a further technical solution, the vertical tunnel thermal storage oxidation device further includes a thermal storage body 800, which is disposed in the air outlet duct 410 of the second combustion chamber 400. Exemplarily, the thermal storage body 800 may be a ceramic thermal storage body. After the exhaust gas is processed by the first combustion chamber 300 and the second combustion chamber 400, the organic exhaust gas is burned and converted into purified gas. When the hot purified gas passes through the cold thermal storage body 800, the thermal storage body 800 absorbs the heat of the purified gas, so that the discharged purified gas is cooled, while the thermal storage body 800 itself is heated, that is, the thermal storage body 800 can realize heat energy recovery, accumulate heat for the furnace environment of the entire oxidation device, and keep the flue gas in the furnace at a high temperature, thereby improving the thermal efficiency of the entire device and reducing the operating cost.

[0045] It should be noted that in the embodiments of the present application, the "flow cross-sectional area" mentioned is usually the flow cross-sectional area of ​​the exhaust gas in each chamber, that is, the channel size formed by each chamber.

[0046] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0047] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A vertical tunnel thermal storage oxidation device, characterized in that: The invention comprises a preheating chamber (100), a combustion chamber (200), a first combustion chamber (300) and a second combustion chamber (400) which are connected in sequence; wherein: a first contraction section (500) is provided between the first combustion chamber (300) and the second combustion chamber (400); a flow cross-sectional area of ​​the first contraction section (500) is smaller than any one of the flow cross-sectional area of ​​the first combustion chamber (300) and the flow cross-sectional area of ​​the second combustion chamber (400); A second constricted section (700) is provided between the preheating chamber (100) and the combustion chamber (200); a flow cross-sectional area of ​​the second constricted section (700) is smaller than any one of a flow cross-sectional area of ​​the preheating chamber (100) and a flow cross-sectional area of ​​the combustion chamber (200); a flow cross-sectional area of ​​the second constricted section (700) is larger than a flow cross-sectional area of ​​the first constricted section (500); and an extension length of the second constricted section (700) is smaller than an extension length of the first constricted section (500).

2. The vertical tunnel thermal regenerative oxidation device according to claim 1, characterized in that: A guide portion (310) is further provided between the first combustion chamber (300) and the first constricted section (500); along the flow direction of the exhaust gas, the flow cross-sectional area of ​​the guide portion (310) gradually decreases, and the small end of the guide portion (310) is in contact with the first constricted section (500).

3. The vertical tunnel thermal regenerative oxidation device according to claim 2, characterized in that: The guide portion (310) comprises a guide surface (311) arranged obliquely relative to the flow direction of the exhaust gas, the included angle between the guide surface (311) and a first direction is α, 45°≤α≤75°, and the first direction is opposite to the flow direction of the exhaust gas.

4. The vertical tunnel thermal regenerative oxidation device according to claim 1, characterized in that: A flow balancing plate (600) is further provided between the combustion chamber (200) and the first combustion chamber (300), and a plurality of flow balancing holes (610) are provided on the flow balancing plate (600).

5. The vertical tunnel thermal regenerative oxidation device according to claim 4, characterized in that: The diameter of the flow balancing hole (610) located in the middle of the flow balancing plate (600) is smaller than the diameter of the flow balancing hole (610) located at the edge of the flow balancing plate (600).

6. The vertical tunnel thermal regenerative oxidation device according to any one of claims 1 to 5, characterized in that: The preheating chamber (100), the combustion chamber (200), the first combustion chamber (300) and the second combustion chamber (400) are arranged upwardly in a longitudinal direction.

7. The vertical tunnel regenerative thermal oxidation device according to claim 1, characterized in that: It also comprises a heat storage body (800), wherein the heat storage body (800) is arranged in the air outlet duct (410) of the second combustion chamber (400).

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