Double-hearth combustion device for co-combustion of coal and biomass

Abstract

The invention discloses a double-hearth combustion device for co-combustion of coal and biomass, and relates to the technical field of combustion equipment. The problems that in an existing coal and biomass mixed combustion technology, combustion is unstable and the burn-off rate is low when biomass is mixed and combusted in a large proportion are solved. An outer-layer furnace is coaxially arranged on the periphery of an inner-layer furnace, the outer wall face of the inner-layer furnace and the inner wall face of the outer-layer furnace share a continuous wall face, the center position of the bottom of the inner-layer furnace is connected with a single pulverized coal swirling burner in a penetrating mode, and a plurality of biomass direct-current burners are evenly arranged at the bottom of the outer-layer furnace in the circumferential direction. The biomass direct-current burner is connected with the outer wall of the inner-layer furnace and the inner wall of the outer-layer furnace through a pose adjusting assembly, and the pose adjusting assembly can control the opening degree of a vertical included angle and the opening degree of a horizontal included angle of the biomass direct-current burner in real time according to different high and low working conditions. By means of fuel partitioned combustion and heat coupling transfer, collaborative combustion of coal and biomass is achieved, and the stability and the efficient co-combustion effect of the two kinds of fuel are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion equipment, and in particular to a double-hearth combustion device for mixed combustion of coal and biomass. Background Art

[0002] The pace of energy structure transformation and low-carbon development is accelerating. Co-combustion technology of coal and biomass has gradually become a research focus in the field of industrial combustion due to its significant advantages in carbon emission reduction and comprehensive resource utilization. Compared with coal, biomass generally has the characteristics of low carbon content, high hydrogen and oxygen content, high moisture content, low calorific value but high volatile matter content. Therefore, biomass fuels are usually very easy to ignite and burn out quickly during the combustion process. For the co-combustion of coal and biomass, due to the differences in the fuel properties of coal and biomass, problems such as unstable combustion and reduced combustion efficiency are prone to occur. Therefore, it is particularly important to solve the problem of combustion instability caused by the different combustion speeds when co-combusting coal and biomass.

[0003] At present, there are many existing technologies for the mixed combustion of coal and biomass. For example, the Chinese invention patent with publication number CN118242662A and publication date of June 25, 2024 discloses a coal-fired boiler biomass co-combustion system. The system proposes to introduce coal and biomass into a mixing bin, fully crush them and evenly mix them through the mixing bin, and then send them into the boiler together, so as to achieve stable combustion and efficient utilization of coal and biomass. This process ensures that coal and biomass are homogenized and burned in the boiler. However, during the mixed combustion of coal and biomass, this system may face the phenomenon of "wind grabbing" generated by biomass in the early stage of combustion. The reason is that in the early stage of combustion, the combustion of biomass rapidly consumes a large amount of oxygen, resulting in a shortened residence time of coal powder particles in an oxygen-sufficient environment, which is not conducive to the burnout of coal powder. A Chinese invention patent with publication number CN119196664A, published on December 27, 2024, discloses a method and system for co-firing biomass in a boiler. This system uses an annular airflow chamber in a pre-mixing device and a rotatable air distribution device to efficiently suspend and evenly mix flaky wood chips and pulverized coal, thereby forming a mixed combustion material. This mixture is then fed into a pulverized coal burner, achieving a fully mixed combustion effect of coal and biomass. However, this invention may also suffer from the "wind grabbing" phenomenon caused by differences in ignition points during the co-firing process of coal and biomass.

[0004] Therefore, in the two coal-biomass co-combustion systems described above, due to the differences in the fuel properties of the two fuels, the biomass rapidly consumes oxygen in a localized area during the initial combustion phase, easily leading to a "wind grabbing phenomenon." This competitive consumption of oxygen between the fuels results in insufficient effective combustion time for the pulverized coal particles in an oxygen-rich environment, which in turn easily leads to staged combustion, resulting in unstable combustion and a reduced burnout rate.

[0005] In summary, given the limitations of current traditional coal and biomass co-firing technology, there is an urgent need to develop a stable and efficient co-firing device to achieve deep coupling and synergistic utilization of the two fuels. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems of unstable combustion and low burnout rate caused by burning a large proportion of biomass in the existing coal and biomass mixed combustion technology, and further provide a dual-furnace combustion device for mixed combustion of coal and biomass.

[0007] The technical solution of the present invention is:

[0008] A double-furnace combustion device for mixed combustion of coal and biomass, the double-furnace combustion device comprising a pulverized coal swirl burner 1, a biomass direct current burner 2, an inner furnace 3 and an outer furnace 4, the inner furnace 3 being arranged vertically, the outer furnace 4 being coaxially arranged on the periphery of the inner furnace 3, the outer wall surface of the inner furnace 3 and the inner wall surface of the outer furnace 4 sharing a continuous wall surface, a single pulverized coal swirl burner 1 being connected through the center position of the bottom of the inner furnace 3, a plurality of biomass direct current burners 2 being evenly arranged circumferentially at the bottom of the outer furnace 4, the biomass direct current burner 2 being connected to the outer wall of the inner furnace 3 and the inner wall of the outer furnace 4 via a posture adjustment component 5, the posture adjustment component 5 being able to control the vertical angle and the horizontal angle opening of the biomass direct current burner 2 in real time according to different working conditions at different heights.

[0009] Furthermore, the pulverized coal swirl burner 1 includes a pulverized coal primary air channel 1-1 and a swirl secondary air channel 1-2. The swirl secondary air channel 1-2 is coaxially arranged on the periphery of the pulverized coal primary air channel 1-1, and a plurality of axial swirl blades uniformly arranged along the circumference are provided in the swirl secondary air channel 1-2.

[0010] Furthermore, the biomass direct current burner 2 includes a biomass primary air channel 2-1 and a direct current secondary air channel 2-2, and the direct current secondary air channel 2-2 is coaxially arranged on the periphery of the biomass primary air channel 2-1.

[0011] Furthermore, the included angle between the center line of the biomass primary air channel 2-1 and the projection of the furnace bottom on the vertical plane is , 30°< <60°.

[0012] Furthermore, the angle between the projection line of the center line of the biomass primary air channel 2-1 on the bottom surface of the furnace and the horizontal center line of the bottom surface of the furnace is , 30°< <60°.

[0013] Furthermore, the posture adjustment component 5 includes a mounting ring 5-1 coaxially nested on the outside of the DC secondary air channel 2-2, and two vertically arranged first rotating shafts 5-2 are respectively provided on both side walls of the DC secondary air channel 2-2, and the other ends of the two first rotating shafts 5-2 are respectively rotatably connected to the left and right ends of the mounting ring 5-1, and a first driven bevel gear 5-3 is installed on the end of one of the first rotating shafts 5-2, and a first driving bevel gear 5-4 meshing with the first driven bevel gear 5-3 is provided on the side of the first driven bevel gear 5-3, and the first driving bevel gear 5-4 is installed on the end of the rotating shaft of the first reduction motor 5-5 arranged vertically above, and the first reduction motor 5-5 is fixedly connected to the mounting ring 5-1 through a motor support plate 5-6. , two second rotating shafts 5-7 arranged vertically are respectively provided at the front and rear ends of the mounting ring 5-1, and the other ends of the two second rotating shafts 5-7 are rotatably connected to the lower parts of two channel connecting plates 5-8 arranged vertically opposite to each other, and the upper parts of the two channel connecting plates 5-8 are fixedly connected to the outer wall of the inner layer furnace 3 and the inner wall of the straight outer layer furnace 4 respectively. A second driven bevel gear 5-9 is installed at the end of one of the second rotating shafts 5-7, and a second driving bevel gear 5-10 meshing with it is provided on the side of the second driven bevel gear 5-9. The second driving bevel gear 5-10 is installed at the end of the rotating shaft of the second reduction motor 5-11 arranged vertically above, and the second reduction motor 5-11 is installed on the channel connecting plate 5-8.

[0014] Furthermore, independent inner furnace exhaust channels and outer furnace exhaust channels are respectively provided on the upper parts of the inner furnace 3 and the outer furnace 4. Both the inner furnace exhaust channels and the outer furnace exhaust channels are L-shaped cylindrical structures. An exhaust channel mounting hole is provided on the side wall of the outer furnace exhaust channel. The end of the inner furnace exhaust channel passes through the exhaust channel mounting hole and extends to the outside of the outer furnace exhaust channel. A valve is installed on the side wall of the inner furnace exhaust channel, which is located inside the outer furnace exhaust channel. The inner furnace exhaust channel and the outer furnace exhaust channel are connected or isolated by the valve.

[0015] Furthermore, the shared wall surface of the inner furnace 3 and the outer furnace 4 is made of a high thermal conductivity material.

[0016] Furthermore, the two bottom inlet end surfaces of the inner furnace 3 and the outer furnace 4 are flush.

[0017] Furthermore, the furnace bodies of the inner furnace 3 and the outer furnace 4 are both cylindrical cavity structures.

[0018] Compared with the prior art, the present invention has the following effects:

[0019] 1. The present invention adopts a double-furnace structure to achieve efficient co-combustion of coal and biomass. In the present invention, pulverized coal is fed into the inner furnace through a pulverized coal swirl burner and burns efficiently therein. At the same time, biomass is fed into the outer furnace through another set of independent biomass direct current burners for combustion. This design, which utilizes the nested structure of the inner and outer furnaces, allows coal and biomass to be independent of each other during the combustion process and not interfere with each other. The two fuels are independently organized to burn in their respective combustion areas. Even when biomass is burned in a large proportion, there will be no "wind rush phenomenon", which is conducive to the efficient combustion of the two fuels. The existing technology mixes coal and biomass in the same combustion space. Biomass has a high volatile matter content and burns quickly. In the early stage of combustion, a large amount of oxygen is consumed, and the "wind rush phenomenon" occurs, resulting in oxygen deficiency in the pulverized coal particles and a reduced burnout rate of the pulverized coal. In addition, the design of independent exhaust channels for the inner and outer furnaces supports two modes: stratified exhaust and mixed exhaust, realizing the classified collection of combustion products and flexible emission control.

[0020] 2. The present invention utilizes a shared high-thermal-conductivity wall surface between the inner and outer furnaces, achieving efficient transfer and sharing of combustion heat and effectively improving combustion stability. In this invention, heat generated by the combustion of pulverized coal in the inner furnace is rapidly transferred to the outer furnace via the shared wall surface, providing an auxiliary heat source for the combustion of the biomass fuel. This enhances biomass combustion stability and prevents problems such as reduced burnout or even fire extinguishing due to insufficient temperatures. Simultaneously, some of the heat generated by the combustion of biomass in the outer furnace is reversely transferred to the inner furnace, forming a complementary heat cycle and further optimizing the overall thermal balance. In particular, the present invention facilitates stable operation under low-load conditions. Existing technologies often employ a single-furnace mixed combustion method. When biomass and pulverized coal are mixed in a single furnace, the biomass, due to its high volatile content, can maintain a relatively fast combustion rate even under low loads. This rapid combustion of the biomass provides the necessary heat source support for the stable combustion of the pulverized coal. However, due to the lack of physical isolation during this process, the biomass preferentially consumes oxygen in the combustion environment. This can cause a lag in the combustion of the pulverized coal, negatively impacting its combustion stability. For the present invention, when the input fuel amount is reduced, under the condition that the two fuel combustion organizations do not affect each other, the heat of the inner and outer furnaces can be transferred to each other through the common wall surface, and the heat is used synergistically. The heat generated by each fuel combustion process can "insulate" the other fuel combustion process, give full play to the role of complementary heat cycle, and ensure the stability of combustion.

[0021] 3. By adding a posture adjustment component 5 to the biomass DC burner 2, the vertical angle is achieved. Angle with horizontal Under high load conditions, the posture adjustment component 5 will increase the vertical angle of the biomass direct current burner 2. Angle with horizontal Under low load conditions, the posture adjustment component 5 will reduce the vertical angle of the biomass direct current burner 2 Angle with horizontal .

[0022] (1) Adjustment under high load conditions:

[0023] Under high load conditions, the fuel in the furnace burns violently, and a large amount of air is needed to ensure that the fuel is fully burned. At this time, increase the vertical angle of the biomass direct current burner. Angle with horizontal , so that the injection direction of the biomass fuel can better match the high-temperature flue gas and air flow field in the furnace, prompting the fuel to be fully mixed with the air in a wider space, which can avoid excessive concentration of fuel at the bottom of the furnace, prevent local overheating, make the temperature distribution in the furnace more uniform, and reduce the probability of slagging and other problems.

[0024] (2) Adjustment under low load conditions:

[0025] Under low load conditions, the amount of fuel in the furnace decreases, the combustion intensity weakens, and it becomes more difficult to maintain stable combustion. At this time, the vertical angle of the biomass DC burner should be reduced. Angle with horizontal , bringing the fuel closer to the high-temperature area at the bottom of the furnace, which helps the fuel ignite quickly and burn stably. At the same time, a smaller injection angle prolongs the fuel's residence time in the furnace, ensuring that the fuel has ample time to come into contact with air and complete the combustion process, preventing the fuel from being discharged from the furnace before it is completely burned, which would reduce combustion efficiency and increase pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a front view of a dual-hearth combustion device for mixed combustion of coal and biomass according to the present invention;

[0027] Figure 2 This is a bottom view of a dual-hearth combustion device for mixed combustion of coal and biomass according to the present invention;

[0028] Figure 3 This is an axonometric diagram of the posture adjustment assembly in a dual-furnace combustion device for mixed combustion of coal and biomass according to the present invention.

[0029] Figure 4 It is a schematic structural diagram of a posture adjustment component in a dual-furnace combustion device for mixed combustion of coal and biomass according to the present invention.

[0030] In the figure: 1. Pulverized coal swirl burner; 1-1. Pulverized coal primary air channel; 1-2. Swirl secondary air channel; 2. Biomass DC burner; 2-1. Biomass primary air channel; 2-2. DC secondary air channel; 3. Inner furnace; 4. Outer furnace; 5. Posture adjustment assembly; 5-1. Mounting ring; 5-2. First rotating shaft; 5-3. First driven bevel gear; 5-4. First driving bevel gear; 5-5. First reduction motor; 5-6. Motor support plate; 5-7. Second rotating shaft; 5-8. Channel connecting plate; 5-9. Second driven bevel gear; 5-10. Second driving bevel gear; 5-11. Second reduction motor. DETAILED DESCRIPTION

[0031] Specific implementation method 1: Combination Figure 1 and Figure 4 The present embodiment is described. The present embodiment is a double-furnace combustion device for mixed combustion of coal and biomass. The double-furnace combustion device includes a pulverized coal swirl burner 1, a biomass direct current burner 2, an inner furnace 3 and an outer furnace 4. The inner furnace 3 is arranged vertically, and the outer furnace 4 is coaxially arranged on the outer periphery of the inner furnace 3. The outer wall surface of the inner furnace 3 and the inner wall surface of the outer furnace 4 share a continuous wall surface. A single pulverized coal swirl burner 1 is connected through the center position of the bottom of the inner furnace 3, and multiple biomass direct current burners 2 are evenly arranged along the circumference of the bottom of the outer furnace 4. The biomass direct current burner 2 is connected to the outer wall of the inner furnace 3 and the inner wall of the outer furnace 4 through a posture adjustment component 5. The posture adjustment component 5 can control the vertical angle and horizontal angle opening of the biomass direct current burner 2 in real time according to different working conditions.

[0032] In this embodiment, pulverized coal is fed into the inner furnace 3 through the pulverized coal swirl burner 1 and is fully combusted within the inner furnace 3 before being discharged. Four biomass DC burners 2 are evenly distributed circumferentially at the bottom of the outer furnace 4. Biomass is fed into the outer furnace 4 through these biomass DC burners 2 and is fully combusted within the outer furnace 4 before being discharged.

[0033] In this embodiment, the inner and outer furnaces 3 and 4 utilize a coaxially nested cylindrical cavity structure, sharing a continuous, highly thermally conductive wall. Heat generated by the combustion of pulverized coal in the inner furnace 3 and heat generated by the combustion of biomass in the outer furnace 4 are transferred to each other through this shared wall. This device achieves synergistic combustion of coal and biomass through zoned fuel combustion and coupled heat transfer, effectively enhancing the stability and efficient co-combustion of both fuels.

[0034] In this embodiment, the inner furnace 3 and the outer furnace 4 are connected by welding the bottom frame and the inner and outer furnace exhaust channels. The connection method of the inner furnace 3 and the outer furnace 4 is the existing technology and will not be repeated here.

[0035] Specific implementation method 2: Combination Figure 1and Figure 4 To describe this embodiment, the pulverized coal swirl burner 1 includes a pulverized coal primary air channel 1-1 and a swirl secondary air channel 1-2. The swirl secondary air channel 1-2 is coaxially arranged around the periphery of the pulverized coal primary air channel 1-1. The swirl secondary air channel 1-2 is provided with a number of axial swirl blades evenly spaced circumferentially. With this arrangement, pulverized coal is delivered to the bottom of the inner furnace through the pulverized coal primary air channel of the pulverized coal swirl burner. The axial swirl blades in the swirl secondary air channel promote thorough mixing of the air and pulverized coal, forming a swirl combustion flame. The axial swirl blades enhance the mixing effect between the pulverized coal and the air. Other components and connections are the same as those in the first embodiment.

[0036] In this embodiment, the pulverized coal swirl burner 1 is fixed to the center of the bottom of the inner furnace 3 by flange welding or bolting to ensure airtightness and structural stability. The connection method between the pulverized coal swirl burner 1 and the inner furnace 3 is prior art and will not be repeated here.

[0037] Specific implementation method three: Combination Figure 1 and Figure 4 To explain this embodiment, the biomass DC burner 2 includes a biomass primary air channel 2-1 and a DC secondary air channel 2-2. The DC secondary air channel 2-2 is coaxially arranged around the biomass primary air channel 2-1. This arrangement allows biomass fuel to be injected into the outer furnace via the circumferentially distributed biomass DC burners. The remaining components and connections are identical to those in Specific Embodiments 1 or 2.

[0038] In this embodiment, the biomass direct current burner 2 adopts a cylindrical structure with a rectangular or circular cross section.

[0039] Specific implementation method four: Combination Figure 1 and Figure 4 To illustrate this embodiment, the included angle between the center line of the biomass primary air channel 2-1 and the bottom surface of the furnace on the vertical plane is , 30°< <60°. In this way, the biomass primary air channel has a vertical angle of 30°~60° The fuel is injected in a directional manner, and the DC secondary air channel simultaneously sends air to form a spiral airflow, which is then burned in the outer furnace. The other components and connection relationships are the same as those of the specific embodiments one, two or three.

[0040] Specific implementation method five: Combination Figure 1 and Figure 4 In this embodiment, the angle between the projection line of the center line of the biomass primary air channel 2-1 on the bottom surface of the furnace and the horizontal center line of the bottom surface of the furnace is , 30°< <60°. In this way, the biomass primary air channel has a horizontal angle of 30°~60° The fuel is injected in a directional manner, and the DC secondary air channel simultaneously sends air to form a spiral airflow, which is then burned in the outer furnace. The other components and connection relationships are the same as those of the specific embodiments one, two, three or four.

[0041] Specific implementation method six: combination Figure 1 and Figure 4 Describing this embodiment, the posture adjustment component 5 of this embodiment includes a mounting ring 5-1 coaxially nested on the outside of the DC secondary air channel 2-2, and two first rotating shafts 5-2 arranged vertically are respectively provided on both side walls of the DC secondary air channel 2-2. The other ends of the two first rotating shafts 5-2 are rotatably connected to the left and right ends of the mounting ring 5-1, and a first driven bevel gear 5-3 is installed on the end of one of the first rotating shafts 5-2. A first driving bevel gear 5-4 meshing with the first driven bevel gear 5-3 is provided on the side of the first driven bevel gear 5-3. The first driving bevel gear 5-4 is installed on the end of the rotating shaft of the first reduction motor 5-5 arranged vertically above. The first reduction motor 5-5 is connected to the mounting ring 5-1 through a motor support plate 5-6. 1 is fixedly connected, and two second rotating shafts 5-7 arranged vertically are respectively provided at the front and rear ends of the mounting ring 5-1. The other ends of the two second rotating shafts 5-7 are respectively rotatably connected to the lower parts of two vertically oppositely arranged channel connecting plates 5-8. The upper parts of the two channel connecting plates 5-8 are respectively fixedly connected to the outer wall of the inner furnace 3 and the inner wall of the straight outer furnace 4. A second driven bevel gear 5-9 is installed at the end of one of the second rotating shafts 5-7. The side of the second driven bevel gear 5-9 is provided with a meshing second active bevel gear 5-10. The second active bevel gear 5-10 is installed at the end of the rotating shaft of the second reduction motor 5-11 arranged vertically above. The second reduction motor 5-11 is installed on the channel connecting plate 5-8. With such a configuration, the posture adjustment component 5 can control the vertical angle of the biomass primary air channel 2-1 in real time according to different working conditions at different heights. Angle with horizontal The biomass direct current burner 2 is fixed to the circumferential position of the bottom of the outer furnace 4 through the posture adjustment component 5, supporting angle adjustment (vertical angle , horizontal angle ) while maintaining a firm connection. The posture adjustment component 5 can control the biomass DC burner 2 to inject fuel and air through a spiral trajectory. The vertical angle of the biomass DC burner 2 Angle with horizontal It is adjustable and used to directional guide the biomass fuel and secondary air flow into the outer furnace 4 combustion zone in a spiral trajectory to enhance the mixing efficiency of the fuel and air.

[0042] Under high load conditions, the posture adjustment component 5 will increase the vertical angle of the biomass primary air channel 2-1. Angle with horizontal Under low load conditions, the posture adjustment component 5 will reduce the vertical angle of the biomass primary air channel 2-1 Angle with horizontal When it is necessary to adjust the vertical angle of the biomass primary air channel 2-1 When the second reduction motor 5-11 drives the second active bevel gear 5-10 to rotate, the second active bevel gear 5-10 is engaged with the second driven bevel gear 5-9, thereby driving the mounting ring 5-1 to swing around the second rotating shaft 5-7; when the horizontal angle of the biomass primary air channel 2-1 needs to be adjusted When the first reduction motor 5-5 drives the first driving bevel gear 5-4 to rotate, the first driving bevel gear 5-4 engages with the first driven bevel gear 5-3, thereby driving the DC secondary air channel 2-2 and the biomass primary air channel 2-1 installed thereon to swing around the first rotating shaft 5-2. The other components and connection relationships are the same as those of the first, second, third, fourth or fifth embodiments.

[0043] Specific implementation method seven: combination Figure 1 and Figure 4 To explain this embodiment, the upper parts of the inner furnace 3 and the outer furnace 4 of this embodiment are respectively provided with independent inner furnace exhaust channels and outer furnace exhaust channels. Both the inner furnace exhaust channels and the outer furnace exhaust channels are L-shaped cylindrical structures. The side wall of the outer furnace exhaust channel is provided with an exhaust channel mounting hole. The end of the inner furnace exhaust channel passes through the exhaust channel mounting hole and extends to the outside of the outer furnace exhaust channel. The inner furnace exhaust channel is located on the side wall of the inner channel cylinder section of the outer furnace exhaust channel. The inner furnace exhaust channel and the outer furnace exhaust channel are connected or isolated by the valve. In this way, the connection or isolation of the inner and outer furnace exhaust channels is controlled by the valve to achieve layered exhaust or mixed exhaust. Other components and connection relationships are the same as those of specific embodiments one, two, three, four, five or six.

[0044] Specific implementation method eight: combination Figure 1 and Figure 4 To explain this embodiment, the shared wall surface of the inner furnace 3 and outer furnace 4 is made of a high-thermal-conductivity material. This arrangement allows heat from combustion to be transferred between the inner and outer furnaces via heat conduction. The remaining components and connections are identical to those in Embodiments 1, 2, 3, 4, 5, 6, or 7.

[0045] Specific implementation method nine: Combination Figure 1 In this embodiment, the two bottom inlet end surfaces of the inner furnace 3 and the outer furnace 4 are flush with each other. Other components and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth, seventh or eighth embodiments.

[0046] Specific implementation method ten: Combination Figure 1 and Figure 4 In this embodiment, the furnace bodies of the inner furnace 3 and the outer furnace 4 are both cylindrical cavity structures. Other components and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth embodiments.

[0047] How it works

[0048] Combine Figure 1 and Figure 4 The working principle of the dual-furnace combustion device for mixed combustion of coal and biomass is described as follows: pulverized coal is fed into the bottom of the inner furnace through the primary air channel of the pulverized coal swirl burner. The axial swirl blades in the swirl secondary air channel promote the thorough mixing of air and pulverized coal, forming a swirl combustion flame. The biomass fuel is injected into the outer furnace through the circumferentially distributed biomass direct current burners. The biomass primary air channel is at a vertical angle of 30° to 60°. Angle with horizontal Fuel is injected in a directionally controlled manner, and air is simultaneously introduced into the DC secondary air channel, forming a spiral airflow that then burns in the outer furnace. During operation of the combustion device, the heat from the inner and outer furnaces can be transferred to each other through the shared wall surface, without interfering with each other's combustion mechanisms. This allows for synergistic heat utilization, with the heat generated by each fuel combustion process serving to "insulate" the other fuel combustion process, fully leveraging the complementary heat cycle and ensuring combustion stability. After combustion is complete, the flue gases generated in the inner and outer furnaces are discharged through the inner and outer furnace exhaust ducts, respectively.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A dual-furnace combustion device for mixed combustion of coal and biomass, characterized by: The double-hearth combustion device comprises a pulverized coal swirl burner (1), a biomass direct current burner (2), an inner furnace (3) and an outer furnace (4); the inner furnace (3) is arranged vertically, the outer furnace (4) is coaxially arranged on the outer periphery of the inner furnace (3), the outer wall surface of the inner furnace (3) and the inner wall surface of the outer furnace (4) share a continuous wall surface, a single pulverized coal swirl burner (1) is connected through the center position of the bottom of the inner furnace (3), and multiple biomass direct current burners (2) are evenly arranged along the circumference of the bottom of the outer furnace (4); the biomass direct current burner (2) is connected to the outer wall of the inner furnace (3) and the inner wall of the outer furnace (4) through a posture adjustment component (5); the posture adjustment component (5) can control the opening of the vertical angle and the horizontal angle of the biomass direct current burner (2) in real time according to different working conditions.

2. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 1, characterized in that: The pulverized coal swirl burner (1) comprises a pulverized coal primary air channel (1-1) and a swirl secondary air channel (1-2). The swirl secondary air channel (1-2) is coaxially arranged on the periphery of the pulverized coal primary air channel (1-1), and a plurality of axial swirl blades uniformly arranged along the circumferential direction are provided in the swirl secondary air channel (1-2).

3. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 1, characterized in that: The biomass direct current burner (2) comprises a biomass primary air channel (2-1) and a direct current secondary air channel (2-2), and the direct current secondary air channel (2-2) is coaxially arranged on the periphery of the biomass primary air channel (2-1).

4. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 3, characterized in that: The included angle between the center line of the biomass primary air channel (2-1) and the projection of the furnace bottom on the vertical plane is , 30°< <60°.

5. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 4, characterized in that: The angle between the projection line of the center line of the biomass primary air channel (2-1) on the bottom of the furnace and the horizontal center line of the bottom of the furnace is , 30°< <60°.

6. A dual-hearth combustion device for mixed combustion of coal and biomass according to claim 4 or 5, characterized in that: The posture adjustment component (5) includes a mounting ring (5-1) coaxially nested on the outside of the DC secondary air channel (2-2), two first rotating shafts (5-2) arranged vertically are respectively provided on both side walls of the DC secondary air channel (2-2), the other ends of the two first rotating shafts (5-2) are rotatably connected to the left and right ends of the mounting ring (5-1), a first driven bevel gear (5-3) is installed at the end of one of the first rotating shafts (5-2), a first driving bevel gear (5-4) meshing with the first driven bevel gear (5-3) is provided on the side of the first driven bevel gear (5-3), the first driving bevel gear (5-4) is installed on the end of the rotating shaft of a first reduction motor (5-5) arranged vertically above, and the first reduction motor (5-5) is fixedly connected to the mounting ring (5-1) via a motor support plate (5-6). Two second rotating shafts (5-7) arranged vertically are respectively provided at the front and rear ends of the mounting ring (5-1), the other ends of the two second rotating shafts (5-7) are respectively rotatably connected to the lower parts of two channel connecting plates (5-8) arranged vertically opposite to each other, and the upper parts of the two channel connecting plates (5-8) are respectively fixedly connected to the outer wall of the inner layer furnace (3) and the inner wall of the straight outer layer furnace (4), a second driven bevel gear (5-9) is installed at the end of one of the second rotating shafts (5-7), and a second driving bevel gear (5-10) meshing with the second driven bevel gear (5-9) is provided on the side of the second driven bevel gear (5-9), and the second driving bevel gear (5-10) is installed on the end of the rotating shaft of a second reduction motor (5-11) arranged vertically above, and the second reduction motor (5-11) is installed on the channel connecting plate (5-8).

7. A dual-hearth combustion device for mixed combustion of coal and biomass according to claim 1, 2, 3, 4 or 5, characterized in that: An independent inner furnace exhaust channel and an outer furnace exhaust channel are respectively provided on the upper parts of the inner furnace (3) and the outer furnace (4). Both the inner furnace exhaust channel and the outer furnace exhaust channel are L-shaped cylindrical structures. A smoke exhaust channel mounting hole is provided on the side wall of the outer furnace exhaust channel. The end of the inner furnace exhaust channel passes through the smoke exhaust channel mounting hole and extends to the outside of the outer furnace exhaust channel. A valve is installed on the side wall of the inner furnace exhaust channel, which is located inside the outer furnace exhaust channel. The inner furnace exhaust channel and the outer furnace exhaust channel are connected or isolated by the valve.

8. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 7, characterized in that: The shared wall surface of the inner furnace (3) and the outer furnace (4) is made of a high thermal conductivity material.

9. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 8, characterized in that: The two bottom inlet end surfaces of the inner furnace (3) and the outer furnace (4) are flush.

10. The dual-hearth combustion device for mixed combustion of coal and biomass according to claim 9, characterized in that: The furnace bodies of the inner furnace (3) and the outer furnace (4) are both cylindrical cavity structures.

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