A secondary combustion chamber and control method for a small domestic waste incineration system

Abstract

The present invention provides a secondary combustion chamber and control method for a small-scale domestic waste incineration system, the secondary combustion chamber comprising: a shell assembly having an inner cavity, a transition pipe disposed within the shell assembly; a radial cyclone disposed within the shell assembly and fixedly connected to the first end of the transition pipe; an axial cyclone disposed between the outer wall of the transition pipe and the inner wall of the shell assembly; the axial cyclone having a rotation direction opposite to that of the radial cyclone, and the axial cyclone dividing the interior of the shell assembly into a combustion zone and an air intake zone; an air supply pipe disposed on the side wall of the shell assembly and connected to the air intake zone; a pyrolysis gas input pipe disposed at the bottom of the shell assembly and fixedly connected to the second end of the transition pipe; a smoke exhaust pipe disposed at the top of the shell assembly, an igniter, and a fuel supply system. The secondary combustion chamber and secondary combustion method provided by the present invention have a wide adaptability to changes in the temperature, flow rate, and composition of the pyrolysis gas, good combustion stability, high combustion efficiency, and are easy to implement automated control of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of harmless disposal, reduction and resource utilization of garbage, and in particular to a secondary combustion chamber and a control method for a small-scale domestic garbage incineration system. Background Art

[0002] The current pyrolysis incineration process for treating domestic waste generates primary combustion flue gas containing a large amount of combustible components, also known as pyrolysis gas. Since the organic combustible components in pyrolysis gas are themselves harmful pollutants, supplementing the pyrolysis gas with oxygen and then performing a secondary premixed combustion process can convert the pyrolysis gas into harmless substances such as carbon dioxide, water, and heat. Therefore, the pyrolysis gas must be fully and thoroughly treated during the secondary combustion process. Otherwise, not only will emissions exceed standards and pollute the environment, but the exhaust gas may also have an odor and color that negatively impacts surrounding residents, creating a NIMBY effect. Therefore, secondary combustion has a significant impact on pollutant emissions from small incineration systems.

[0003] The thorough and effective treatment of pyrolysis gas requires addressing two key issues: First, the composition of the pyrolysis gas must be relatively stable, with no intermittent fluctuations, which is crucial for the development of pyrolysis technology. Second, efficient secondary combustion technology for the pyrolysis gas must be developed to improve the combustion efficiency and, therefore, the complete decomposition of the combustible components. The first issue hinges on the development of efficient pyrolysis gasifiers, while the second relies on the development of efficient secondary combustion mechanisms.

[0004] For the pyrolysis gas produced by small-scale domestic waste pyrolysis furnaces, since the parameters such as the flow rate, composition, and temperature of the pyrolysis gas are often not stable, it is necessary to develop a mechanism for the secondary combustion of the pyrolysis gas, which has a wide adaptability range of flow rate and combustible component concentration, high combustion efficiency, and the ability to rely on the control system for automatic ignition. This is of great significance to the development of small-scale domestic waste clean incineration technology. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a secondary combustion chamber and control method for a small domestic waste incineration system, so as to enhance the adaptability to changes in the flow rate and composition of pyrolysis gas within a large range during the combustion process, and improve the combustion efficiency of the pyrolysis gas.

[0006] To solve the above technical problems, an embodiment of the present invention provides a secondary combustion chamber for a small-scale domestic waste incineration system, the secondary combustion chamber comprising:

[0007] A shell assembly having an inner cavity, wherein a transition pipe is provided inside the shell assembly;

[0008] a radial swirler disposed inside the housing assembly and fixedly connected to the first end of the transition duct;

[0009] an axial swirler disposed between the outer wall of the transition duct and the inner wall of the housing assembly;

[0010] The axial swirler has a rotation direction opposite to that of the radial swirler, and the axial swirler divides the interior of the housing assembly into a combustion zone and an air intake zone;

[0011] An air supply pipe provided on a side wall of the housing assembly and in communication with the air intake area;

[0012] a pyrolysis gas input pipe disposed at the bottom of the shell assembly and fixedly connected to the second end of the transition pipe;

[0013] a smoke exhaust pipe disposed on the top of the shell assembly;

[0014] an igniter communicated with the combustion zone and disposed on a side wall of the housing assembly; and a fuel supply system connected to the igniter.

[0015] Optionally, at least one of an outlet temperature sensor or an oxygen content sensor is provided on the smoke exhaust pipe; and / or, an air temperature sensor is provided on the air supply pipe; and / or, an inlet temperature sensor is provided on the pyrolysis gas input pipe.

[0016] Optionally, the radial swirler includes:

[0017] a first circular plate; and a second circular plate disposed parallel to the first circular plate;

[0018] The first circular plate and the second circular plate are provided with mounting holes for the transition pipe to pass through;

[0019] A plurality of radial guide vanes are provided between the first circular plate and the second circular plate with the transition duct as the symmetrical center;

[0020] The gap between any two adjacent radial guide vanes forms a radial air passage.

[0021] Optionally, the swirl number of the radial swirler ranges from 0.45 to 2.15.

[0022] Optionally, the axial swirler includes:

[0023] a first circular ring, and a second circular ring disposed outside the first circular ring;

[0024] A plurality of axial guide vanes are provided between the first circular ring and the second circular ring with the first circular ring as the symmetrical center;

[0025] The gap between any two adjacent axial guide vanes forms an axial air channel.

[0026] Optionally, the swirl number of the axial swirler ranges from 0.4 to 1.6.

[0027] Optionally, a porous plate is provided in the combustion zone, and a plurality of heat storage bodies are provided on the porous plate.

[0028] Optionally, the secondary combustion chamber for a small-scale domestic waste incineration system further includes: a maintenance hole provided on the side wall of the shell assembly and connected to the air intake area.

[0029] An embodiment of the present invention further provides a control method for a secondary combustion chamber of a small-scale domestic waste incineration system, which uses the secondary combustion chamber described above and includes the following steps:

[0030] The pyrolysis gas enters the transition pipe through the pyrolysis gas input pipe and enters the combustion zone through the radial cyclone;

[0031] The mixed combustion air enters the air intake area through the air supply pipe and enters the combustion area through the axial swirler;

[0032] When the pyrolysis gas contacts and mixes with the combustion air, the igniter is turned on for combustion.

[0033] Optionally, the secondary combustion method of pyrolysis gas further includes:

[0034] When the oxygen content sensor value on the exhaust pipe is greater than 6%, reduce the flow rate of the mixed combustion air; when the oxygen content sensor value is less than 3%, increase the flow rate of the mixed combustion air;

[0035] When the value of the outlet temperature sensor on the exhaust pipe is less than 850°C, and the difference between the value of the outlet temperature sensor and the air temperature sensor on the air supply pipe, and the difference between the value of the outlet temperature sensor and the inlet temperature sensor on the pyrolysis gas input pipe are both less than 300°C, the igniter stops operating;

[0036] When the value of the outlet temperature sensor on the exhaust pipe is less than 850°C, and the difference between the value of the outlet temperature sensor and the value of the air temperature sensor on the air supply pipe; and the difference between the value of the outlet temperature sensor and the value of the inlet temperature sensor on the pyrolysis gas input pipe are greater than or equal to 300°C, the igniter maintains operation;

[0037] When the value of the outlet temperature sensor on the smoke exhaust pipe is greater than or equal to 850° C., the igniter stops operating.

[0038] The above solution of the present invention includes at least the following beneficial effects:

[0039] The secondary combustion chamber provided by the above-mentioned scheme of the present invention uses a double swirl mechanism to cause the mixed combustion air and pyrolysis gas entering the secondary combustion chamber to undergo reverse swirl, forming a large-volume high-temperature reflux zone in the combustion chamber. This not only has excellent adaptability to changes in the flow rate and composition of the pyrolysis gas within a large range, but also makes the combustible components in the pyrolysis gas have very high combustion efficiency during combustion, and its operating state can be automatically adjusted through the control system to achieve the optimal overall operating effect.

[0040] Specifically: 1) The swirler disposed within the housing assembly creates a large high-temperature recirculation zone and high turbulence intensity within the secondary combustion chamber, thereby enhancing the mixing of combustible components with high-temperature flue gas and improving combustion stability. This allows the secondary combustion chamber to be well adapted to fluctuations in the temperature and flow rate of the pyrolysis gas, as well as the concentration of combustible components in the pyrolysis gas, within a wide range;

[0041] 2) By providing at least one sensor on each of the air inlet and outlet pipes, the amount of co-combustion air supplied can be dynamically adjusted, effectively preventing problems such as excessive co-combustion air causing a decrease in the temperature in the combustion chamber and insufficient co-combustion air causing an inadequate reaction, thereby achieving high combustion efficiency. This means a high removal rate of combustible components in the pyrolysis gas, laying a solid foundation for meeting flue gas emission standards.

[0042] 3) Easy to ignite and easy to realize automatic control of the secondary combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A front view of a secondary combustion chamber for treating pyrolysis gas provided by an embodiment of the present invention;

[0044] Figure 2 for Figure 1 AA section view;

[0045] Figure 3 for Figure 1 A partial enlarged view of point Ⅰ;

[0046] Figure 4 for Figure 2 BB cross-sectional view;

[0047] Figure 5 It is an axonometric view of a radial cyclone;

[0048] Figure 6 This is the axonometric view of the axial cyclone;

[0049] Explanation of the accompanying symbols: 1. Outlet temperature sensor; 2. Exhaust gas; 3. Oxygen content sensor; 4. Shell assembly; 5. High-temperature flue gas; 6. Combustion zone; 7. Ignition section; 8. Air supply pipe; 9. Blended air; 10. Air temperature sensor; 11. Fuel supply system; 12. Pyrolysis gas; 13. Air inlet; 14. Inlet temperature sensor; 15. Inlet zone; 16. Maintenance hole; 17. Transition duct; 18. Axial swirler; 19. Radial swirler; 20. Recirculation zone; 21. Porous plate; 22. Heat storage body; 23. Exhaust pipe; 24. Radial guide vane; 25. Radial air duct; 26. First plate; 27. Second plate; 28. Mounting hole; 29. ​​Axial guide vane; 30. Axial air duct; 31. First ring; 32. Second ring. DETAILED DESCRIPTION

[0050] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0051] like Figure 1 As shown, an embodiment of the present invention provides a secondary combustion chamber for a small-scale domestic waste incineration system, the secondary combustion chamber comprising: a shell assembly 4 having an inner cavity, a transition pipe 17 provided inside the shell assembly 4; a radial swirler 19 disposed inside the shell assembly 4 and fixedly connected to a first end of the transition pipe 17; an axial swirler 18 disposed between an outer wall of the transition pipe 17 and an inner wall of the shell assembly 4; the axial swirler 18 divides the interior of the shell assembly 4 into a combustion zone 6 and an air intake zone; an air supply pipe 8 disposed on a side wall of the shell assembly 4 and communicating with the air intake zone 15;

[0052] A pyrolysis gas input pipe 13 is provided at the bottom of the shell assembly 4 and fixedly connected to the second end of the transition pipe 17; and a smoke exhaust pipe 23 is provided at the top of the shell assembly 4.

[0053] In this embodiment, the shell assembly 4 is configured as a cylindrical cavity that accommodates other components such as the transition pipe 17, the axial swirler 18 and the radial swirler 19; a smoke exhaust pipe 23 is provided on the top of the shell assembly 4, a pyrolysis gas input pipe 13 is provided at the bottom of the shell assembly 4, and an air supply pipe 8 is provided on the side wall of the shell assembly 4; the axial swirler 18 is provided between the outer wall of the transition pipe 17 and the inner wall of the shell assembly 4, and divides the cylindrical inner cavity of the shell assembly 4 into two parts, the upper part is the combustion zone 6, and the lower part is the air inlet zone 15, and the radial swirler 19 is in the combustion zone 6; one end of the transition pipe 17 is fixedly connected to the radial swirler 19 Then, the other end of the transition pipe 17 is connected to the air inlet pipe at the bottom of the shell assembly 4. The positional relationship between the transition pipe 17 and the axial swirler 18 is set to prevent the pyrolysis gas 12 from contacting the mixed combustion air 9. When the secondary combustion chamber is burning, the pyrolysis gas 9 enters the combustion zone 6 of the shell assembly 4 in sequence through the pyrolysis gas inlet pipe 13 at the bottom of the shell assembly 4, the transition pipe 17 and the radial swirler 19. The mixed combustion air 9 enters the combustion zone 6 of the shell assembly 4 in sequence through the air supply pipe 8 on the side wall of the shell assembly 4 and the axial swirler 18, and is premixed and burned with the pyrolysis gas 12. The generated high-temperature flue gas 5 is discharged from the secondary combustion chamber through the exhaust pipe 23.

[0054] Since the radial swirler 19 rotates in opposite directions to the axial swirler 18, the relative flow velocity of the pyrolysis gas 12 and the combustion air 9 at the contact point in the combustion zone 6 decreases rapidly, and a series of vortices are "rubbed" out in the contact area, that is, the macroscopic relative flow velocity of the two air flows at the contact point decreases, but the local turbulence intensity is very large, which is very conducive to the combustion reaction between the pyrolysis gas 12 and the combustion air 9, and the reaction maintains a sufficiently high combustion efficiency. The area where the pyrolysis gas 12 and the combustion air 9 air flows intersect is the flame front.

[0055] At the same time, due to the action of the cyclone, a part of the high-temperature flue gas 5 generated after combustion refluxes and mixes with the two subsequent airflows, thereby increasing the temperature of the subsequent airflows and promoting the combustion reaction, thereby stabilizing the flame. The secondary combustion chamber is capable of regulating parameters such as the flow rate, composition, and temperature of the pyrolysis gas 12 to adapt to fluctuations within a larger range while still having good stability.

[0056] An igniter 7 is mounted on the side wall of the housing assembly 4 and communicates with the combustion zone 6; and a fuel supply system 11 is connected to the igniter 7. When the combustion chamber ignites or flames out during operation and needs to be re-ignited, the igniter 7 is activated, and the fuel supply system 11 delivers fuel to the igniter. The igniter 7 generates a torch, which ignites the pyrolysis gas. One end of the igniter 7 is located within the combustion zone 6, and the other end of the igniter 7 is connected to the fuel supply system 11, ensuring the combustion of the mixed gas.

[0057] In an optional embodiment of the present invention, the secondary combustion chamber of the pyrolysis gas further includes: a maintenance hole 16 provided on the side wall of the shell assembly 4.

[0058] In this embodiment, a maintenance hole 16 leading to the air intake area 15 is provided on the side wall of the shell assembly 4. The maintenance hole 16 is in a closed state when the secondary combustion chamber is in operation and is only opened when inspection and maintenance are required, and is also opened to facilitate cleaning of dust accumulated in the air intake area 15.

[0059] In an optional embodiment of the present invention, at least one of an outlet temperature sensor 1 or an oxygen content sensor 3 is provided on the smoke exhaust pipe 23; and / or, an air temperature sensor 10 is provided on the air supply pipe 8; and / or, an inlet temperature sensor 14 is provided on the pyrolysis gas input pipe 13.

[0060] In this embodiment, by setting sensors to monitor the temperature and the content of combustion components in real time, the amount of co-combustion air supplied is dynamically adjusted, which can effectively prevent the problem of excessive co-combustion air causing a decrease in temperature in the combustion chamber and insufficient reaction caused by too little co-combustion air, further improve the combustion efficiency, and increase the removal rate of combustible components in the pyrolysis gas; specifically: the setting of the oxygen content sensor 3 is mainly used to detect the oxygen content in the exhaust flue gas flowing through the exhaust pipe 23 after combustion, and further control the flow rate of the pyrolysis gas 12 or the flow rate of the co-combustion air 9; thereby making the secondary combustion chamber have a wide adaptability range to fluctuations in the flow rate of the pyrolysis gas 12; the setting of the outlet temperature sensor 1, the air temperature sensor 10 and the inlet temperature sensor 14 are mainly used to detect the gas temperature at the mouth of the pyrolysis gas input pipe 13 and the exhaust pipe 23, so as to determine whether the secondary combustion chamber is successfully ignited, so as to control the igniter 7 to ensure the normal operation of the secondary combustion chamber.

[0061] In an optional embodiment of the present invention, the radial swirler 19 is described as including: a first circular plate 26; a second circular plate 27 arranged parallel to the first circular plate 26; a mounting hole 28 for the transition duct 17 to pass through is provided on the first circular plate 26 and the second circular plate 27; a plurality of radial guide vanes 24 are provided between the first circular plate 26 and the second circular plate 27 with the transition duct 17 as the symmetrical center; and a gap between any two adjacent radial guide vanes 24 forms a radial airway 25.

[0062] In this embodiment, Figure 4 and Figure 5 As shown, the first circular plate 26 and the second circular plate 27 are both configured as circular plates, and the first circular plate 26 and the second circular plate 27 are matched with the transition pipe 17 through the mounting holes 28, as shown in FIG. Figure 3 As shown, the transition duct 17 is communicated with the interior of the radial swirler 19 so that the pyrolysis gas 12 can enter the interior of the radial swirler 19 from the transition duct 17; a plurality of radial guide vanes 24 are provided between the first circular plate 26 and the second circular plate 27, and the plurality of radial guide vanes 24 are rotationally symmetrical about the center line of the transition duct 17, and the gap between any two adjacent radial guide vanes 24 forms a radial air channel 25. After the pyrolysis gas 12 enters the interior of the radial swirler 19, it enters the combustion zone 6 through the radial air channel 25; further, in order to ensure that the pyrolysis gas 12 has sufficient swirl when entering the combustion zone 6, the swirl number of the radial swirler 19 is set within a certain range.

[0063] In an optional embodiment of the present invention, the axial swirler 18 is described. The axial swirler 18 includes: a first circular ring 31, and a second circular ring 32 arranged outside the first circular ring; a plurality of axial guide vanes 29 are provided between the first circular ring 31 and the second circular ring 32 with the first circular ring 31 as the symmetrical center; the gap between any two adjacent axial guide vanes 29 forms an axial airway 30.

[0064] In this embodiment, Figure 6As shown, the first ring 31 serves as the inner ring, and the second ring 32 serves as the outer ring. A plurality of axial guide vanes 29 are provided between the inner ring and the outer ring. The plurality of axial guide vanes 29 are rotationally symmetrical about the central axis of the first ring 31, and the gap between any two adjacent axial guide vanes 29 forms an axial air channel 30. The axial swirler 18 is installed in such a manner that the outer ring 32 cooperates with the inner wall of the shell assembly 4, and the inner ring 31 cooperates with the outer wall of the transition duct 17. The co-combustion air 9 enters the air intake zone through the air intake pipe on the side wall of the shell assembly 4, and enters the combustion zone 6 through the axial air channel 30. Furthermore, in order to ensure that the co-combustion air 9 has sufficient swirl when entering the combustion chamber 6, the swirl number of the axial swirler 18 is set within a certain range.

[0065] In an optional embodiment of the present invention, the swirl numbers of the radial swirler 19 and the axial swirler 18 are set to different values.

[0066] In this embodiment, the swirl number of the radial swirler 19 is the ratio of the tangential momentum to the radial momentum of the pyrolysis gas when it flows out from the inside to the outside through the radial air channel 25. The swirl number of the axial swirler 18 is the ratio of the tangential momentum to the axial momentum of the pyrolysis gas when it flows out from the bottom to the top through the axial air channel 30. Furthermore, the swirl number of the radial swirler 19 is set to a value between 0.45 and 2.15, and the swirl number of the axial swirler 18 is set to a value between 0.4 and 1.6. The swirl number of the axial swirler 18 is set to a value between 0.4 and 1.6.

[0067] Since the swirl numbers of the radial swirler 19 are different from those of the axial swirler 18, and the swirl number of the radial swirler 19 is greater than that of the axial swirler 18, the high-temperature flue gas 5 generated by the mixed combustion of the pyrolysis gas 12 and the combustion air 9 will form a huge high-temperature recirculation zone 20 in the combustion zone 6 and downstream of the radial swirler 19, that is, a part of the high-temperature flue gas 5 will be mixed with the subsequent two airflows after reflowing, thereby increasing the temperature of the subsequent airflow and promoting the combustion reaction, thereby stabilizing the flame. When the flow rate, composition, temperature and other parameters of the pyrolysis gas 12 fluctuate within a large range, the stability of the secondary combustion chamber during operation is further guaranteed.

[0068] In an optional embodiment of the present invention, the center line of the air supply pipe 8 is not aligned with the center line of the air intake area 15 .

[0069] In this embodiment, Figure 2As shown, when the air supply pipe 8 is connected to the air intake zone 15, the center line of the air supply pipe 8 is not in the same plane as the center line of the air intake zone 15, that is, the center line of the air supply pipe 8 is neither parallel to nor intersecting with the center line of the air intake zone 15, so that the combustion air 9 has an initial rotation when entering the air intake zone 15, so that the combustion air 9 has an ideal rotation after passing through the axial swirler 18 and entering the combustion zone 6.

[0070] In an optional embodiment of the present invention, a porous plate 21 is provided in the combustion zone 6 , and a plurality of heat storage bodies 22 are provided on the porous plate 21 .

[0071] In this embodiment, the plurality of heat storage bodies 22 are mainly used to absorb or release heat from the high-temperature flue gas 5 generated by combustion. Preferably, the plurality of heat storage bodies 22 can be ceramic spheres or spherical shapes with an equivalent diameter of 20-50 mm. Of course, the heat storage bodies are not limited to ceramic materials or spherical shapes. Other materials or shapes that are easy to absorb or release heat and are resistant to high temperatures, corrosion, and thermal shock can also be used.

[0072] It should be noted that the working principle of the multiple heat storage bodies 22 is that when the temperature of the high-temperature flue gas 5 flowing out of the combustion zone 6 is high as measured by the outlet temperature sensor 1, when the high-temperature flue gas 5 passes through the heat storage body 22, a part of the heat flow is stored in the heat storage body 22 through the heat absorption effect of the heat storage body 22; when the temperature of the high-temperature flue gas 5 is low as measured by the outlet temperature sensor 1, the heat storage body 22 heats the high-temperature flue gas 5, and the heat stored in the heat storage body 22 returns to the high-temperature flue gas 5 again, thereby producing two positive effects: first, it makes the temperature fluctuation of the exhaust flue gas smaller, thereby reducing the thermal load impact on the downstream system; second, after the high-temperature flue gas 5 drops instantaneously, the hot heat storage body 22 is conducive to promoting the removal of unburned combustible components in the high-temperature flue gas 5, thereby improving the comprehensive combustion efficiency of the secondary combustion chamber.

[0073] An embodiment of the present invention further provides a control method for a secondary combustion chamber of a small-scale domestic waste incineration system, which uses the secondary combustion chamber described in any of the above embodiments and includes the following steps:

[0074] Step 11: The pyrolysis gas 12 enters the transition pipe 17 through the pyrolysis gas input pipe 13 and enters the combustion zone 6 through the radial cyclone 19;

[0075] Step 12: The mixed combustion air 9 enters the air inlet zone 15 through the air supply pipe 8 and enters the combustion zone 6 through the axial swirler 18;

[0076] Step 13: After the pyrolysis gas 12 contacts and mixes with the combustion air 9, the igniter 7 is turned on for combustion.

[0077] In this embodiment, the pyrolysis gas 12 enters the transition pipe 17 through the inlet pipe 13, and then enters the combustion zone 6 through the radial swirler 19. At the same time, the mixed combustion air 9 enters the combustion zone 6 through the air supply pipe 8 to the air inlet zone 15, and then enters the combustion zone 6 through the axial swirler 18. When the pyrolysis gas 12 and the mixed combustion air 9 are in contact and mixed, the ignition device is turned on for combustion. Since the radial swirler 19 and the axial swirler 18 have opposite rotation directions, the relative flow velocity of the pyrolysis gas 12 and the mixed combustion air 9 in the contact area in the combustion zone 6 drops rapidly, and a series of vortices are "rubbed" out in the contact area. That is, the macroscopic relative flow velocity of the two air flows in the contact area is not large, but the local turbulence intensity is very high, which is conducive to the combustion reaction between the pyrolysis gas and the mixed combustion air, and the reaction maintains a sufficiently high combustion efficiency. The intersection of the two air flows is the flame front.

[0078] When the pyrolysis gas 12 and the mixed combustion air 12 are burned, an oxidation reaction occurs, releasing heat, forming high-temperature flue gas 5 in the combustion chamber. Since the swirl number of the radial swirler 19 is greater than that of the axial swirler 18, the high-temperature flue gas 5 will form a huge recirculation zone 20 downstream of the radial swirler. The recirculated high-temperature flue gas will heat up the subsequent two airflows, further promoting the combustion reaction, thereby stabilizing the flame. Even if the combustible components in the pyrolysis gas decrease in a short period of time, the existence of the high-temperature recirculation zone will maintain the combustible components in the pyrolysis gas to meet the conditions for oxidation reaction, thereby making the secondary combustion chamber have a wide adaptability to fluctuations in the pyrolysis gas composition.

[0079] In an optional embodiment of the present invention, the control method for the secondary combustion chamber of the small-scale domestic waste incineration system further includes: when the value of the oxygen content sensor 3 on the exhaust pipe 23 is greater than 6%, reducing the flow rate of the mixed combustion air 9; when the value of the oxygen content sensor 3 is less than 3%, increasing the flow rate of the mixed combustion air 9; when the value of the outlet temperature sensor 1 on the exhaust pipe 23 is less than 850°C, and the difference between the value of the outlet temperature sensor 1 and the air temperature sensor 10 on the air supply pipe 8, the outlet temperature sensor 1 and the inlet temperature sensor on the pyrolysis gas input pipe 13 are 14 are all less than 300℃, the igniter 7 stops running; when the value of the outlet temperature sensor 1 on the exhaust pipe 23 is less than 850℃, and the difference between the outlet temperature sensor 1 and the air temperature sensor 10 on the air supply pipe 8; and the difference between the outlet temperature sensor 1 and the inlet temperature sensor 14 on the pyrolysis gas input pipe 13 are greater than or equal to 300℃, the igniter 7 maintains operation; when the value of the outlet temperature sensor 1 on the exhaust pipe 23 is greater than or equal to 850℃, the igniter 7 stops running.

[0080] In this embodiment, when the secondary combustion is working, when the flow rate of the pyrolysis gas changes, the required amount of co-combustion air will also change: when the pyrolysis gas flow rate increases, the concentration of the oxygen component in the exhaust gas will decrease, that is, the value measured by the oxygen content sensor 3 will decrease; when the pyrolysis gas flow rate decreases, the concentration of the oxygen component in the exhaust gas will increase, that is, the value of the oxygen content sensor will increase; specifically: when the value of the oxygen content sensor 3 is greater than 6%, the flow rate of the co-combustion air 9 is reduced; when the value of the oxygen content sensor 3 is less than 3%, the flow rate of the co-combustion air 9 is increased; the oxygen content in the exhaust gas flowing through the exhaust pipe 23 after combustion detected by the oxygen content sensor 3 is further used to control the flow rate of the pyrolysis gas or the flow rate of the co-combustion air; thereby, the secondary combustion chamber has a wide adaptability range to fluctuations in the pyrolysis gas flow rate;

[0081] When the secondary combustion chamber goes out during ignition operation and needs to be ignited again, the igniter 7 will start, the fuel supply system 11 will supply fuel to the igniter 7, and the igniter 7 will generate a torch to ignite the pyrolysis gas through the torch; after successful ignition, the igniter 7 stops working; the outlet temperature sensor 1 on the exhaust pipe 23, the air temperature sensor 10 on the air supply pipe 8 and the inlet temperature sensor 14 on the pyrolysis gas input pipe 13 are provided to monitor the gas temperature at the pipe openings of the inlet pipe and the outlet pipe in real time to determine whether the secondary combustion chamber has been successfully ignited;

[0082] Specifically: when the value monitored by the outlet temperature sensor 1 is greater than or equal to 850°C, it indicates that the secondary combustion chamber has been successfully ignited. At this time, the igniter 7 can be turned off to avoid fuel waste. When the value of the outlet temperature sensor 1 on the exhaust pipe 23 is less than 850°C, and the difference between the value of the outlet temperature sensor 1 and the air temperature sensor 10 on the air supply pipe 8, and the difference between the value of the outlet temperature sensor 1 and the inlet temperature sensor 14 on the pyrolysis gas input pipe 13 is greater than or equal to 300°C, the igniter 7 is kept running to make the reaction of the pyrolysis gas in the secondary combustion chamber more complete.

[0083] When the value of the outlet temperature sensor 1 on the exhaust pipe 23 is less than 850°C, and the difference between the values ​​of the outlet temperature sensor 1 and the air temperature sensor 10 on the air supply pipe 8, and the difference between the values ​​of the outlet temperature sensor 1 and the inlet temperature sensor 14 on the pyrolysis gas input pipe 13 are both less than 300°C, the igniter 7 stops running and the waste incineration system shuts down.

[0084] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A secondary combustion chamber for a small domestic waste incineration system, characterized in that: The secondary combustion chamber comprises: A housing assembly (4) having an inner cavity, wherein a transition pipe (17) is provided inside the housing assembly (4); a radial swirler (19) disposed inside the housing assembly (4) and fixedly connected to the first end of the transition pipe (17); an axial swirler (18) disposed between the outer wall of the transition duct (17) and the inner wall of the housing assembly (4); The axial swirler (18) and the radial swirler (19) have opposite rotation directions, and the axial swirler (18) divides the interior of the housing assembly (4) into a combustion zone (6) and an air intake zone (15); an air supply pipe (8) disposed on a side wall of the housing assembly (4) and communicating with the air intake area (15); a pyrolysis gas input pipe (13) disposed at the bottom of the housing assembly (4) and fixedly connected to the second end of the transition pipe (17); a smoke exhaust pipe (23) disposed on the top of the housing assembly (4); an igniter (7) in communication with the combustion zone (6) and disposed on a side wall of the housing assembly (4); and a fuel supply system (11) connected to the igniter (7); The radial cyclone (19) comprises: A first circular plate (26); a second circular plate (27) arranged parallel to the first circular plate (26); The first circular plate (26) and the second circular plate (27) are provided with mounting holes (28) for the transition pipe (17) to pass through; A plurality of radial guide vanes (24) are provided between the first circular plate (26) and the second circular plate (27) with the transition duct (17) as a symmetrical center; The gap between any two adjacent radial guide vanes (24) forms a radial air passage (25); The swirl number of the radial swirler (19) ranges from 0.45 to 2.15; The axial swirler (18) comprises: a first circular ring (31), and a second circular ring (32) disposed outside the first circular ring; A plurality of axial guide vanes (29) are provided between the first circular ring (31) and the second circular ring (32) with the first circular ring (31) as the symmetrical center; The gap between any two adjacent axial guide vanes (29) forms an axial airway (30); The swirl number of the axial swirler (18) is in the range of 0.4-1.6; The pyrolysis gas (9) sequentially enters the combustion zone (6) of the shell assembly (4) through the pyrolysis gas inlet pipe (13) at the bottom of the shell assembly (4), the transition pipe (17), and the radial swirler (19), and the mixed combustion air (9) sequentially enters the combustion zone (6) of the shell assembly (4) through the air supply pipe (8) on the side wall of the shell assembly (4) and the axial swirler (18), and is premixed and burned with the pyrolysis gas (12); The radial swirler (19) and the axial swirler (18) have different swirl numbers, and the swirl number of the radial swirler (19) is greater than the swirl number of the axial swirler (18); The center line of the air supply pipe (8) is not aligned with the center line of the air intake area (15); A porous plate (21) is provided in the combustion zone (6), and a plurality of heat storage bodies (22) are provided on the porous plate (21).

2. The secondary combustion chamber for a small-scale domestic waste incineration system according to claim 1, characterized in that: The exhaust pipe (23) is provided with at least one of an outlet temperature sensor (1) or an oxygen content sensor (3); and / or, The air supply pipe (8) is provided with an air temperature sensor (10); and / or, The pyrolysis gas input pipe (13) is provided with an inlet temperature sensor (14).

3. The secondary combustion chamber for a small-scale domestic waste incineration system according to claim 1, characterized in that: Also includes: A maintenance hole (16) is provided on the side wall of the housing assembly (4) and is in communication with the air intake area (15).

4. A control method for a secondary combustion chamber of a small domestic waste incineration system, characterized in that: Using the secondary combustion chamber according to any one of claims 1 to 3 comprises the following steps: The pyrolysis gas (12) enters the transition pipe (17) through the pyrolysis gas input pipe (13), and enters the combustion zone (6) through the radial cyclone (19); The mixed combustion air (9) enters the air inlet zone (15) through the air supply pipe (8), and enters the combustion zone (6) through the axial swirler (18); When the pyrolysis gas (12) contacts and mixes with the combustion air (9), the igniter (7) is turned on to start combustion.

5. The control method for the secondary combustion chamber of a small-scale domestic waste incineration system according to claim 4, characterized in that: Also includes: When the value of the oxygen content sensor (3) on the exhaust pipe (23) is greater than 6%, the flow rate of the mixed combustion air (9) is reduced; When the value of the oxygen content sensor (3) is less than 3%, the flow rate of the mixed combustion air (9) is increased; When the value of the outlet temperature sensor (1) on the exhaust pipe (23) is less than 850°C, and the difference between the value of the outlet temperature sensor (1) and the air temperature sensor (10) on the air supply pipe (8), and the difference between the value of the outlet temperature sensor (1) and the inlet temperature sensor (14) on the pyrolysis gas input pipe (13) are all less than 300°C, the igniter (7) stops operating; When the value of the outlet temperature sensor (1) on the exhaust pipe (23) is less than 850°C, and the difference between the values ​​of the outlet temperature sensor (1) and the air temperature sensor (10) on the air supply pipe (8); and When any difference between the values ​​of the outlet temperature sensor (1) and the inlet temperature sensor (14) on the pyrolysis gas input pipe (13) is greater than or equal to 300° C., the igniter (7) maintains operation; When the value of the outlet temperature sensor (1) on the smoke exhaust pipe (23) is greater than or equal to 850°C, the igniter (7) stops operating.

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