Biomass fuel heat supply system

Abstract

The invention discloses a biomass fuel heat supply system, belongs to the technical field of biomass utilization, and aims to solve the problem of low combustion efficiency caused by insufficient mixing of pyrolysis gas and oxidizing gas or oxidizing gas in the prior art. According to the biomass fuel heat supply system, an expanding circular truncated cone and a rotational flow blade which are coaxial with a combustion inner cavity are arranged in the combustion inner cavity, a gap is formed between the outer wall of the expanding circular truncated cone and the inner wall of the combustion inner cavity, the outer wall of the expanding circular truncated cone is sleeved with the rotational flow blade, and the inner end of the rotational flow blade is fixedly connected with the expanding circular truncated cone; the outer ends of the rotational flow blades are fixedly connected with the inner wall of the combustion inner cavity, the rotational flow blades are located in a gap between the outer wall of the diameter-expanding circular truncated cone and the inner wall of the combustion inner cavity, a plurality of rotational flow air holes are formed in the side wall of the combustion inner cavity, and oxidizing gas is supplied into the combustion inner cavity through the rotational flow air holes. The invention can be used for combustion of biomass pyrolysis gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass utilization, and in particular relates to a biomass fuel heating system. Background Art

[0002] Biomass pyrolysis gas, a key product of biomass energy conversion, is produced by carbonizing biomass under anaerobic or oxygen-free conditions. Its main components include hydrogen and carbon monoxide. Efficient combustion of biomass pyrolysis gas can convert it into useful energy forms such as heat and electricity, thereby effectively utilizing biomass energy.

[0003] When existing biomass fuel heating equipment processes biomass cracking gas, the cracking gas is directly mixed with oxidizing gas or the oxidizing gas is burned, resulting in insufficient mixing of the two and low combustion efficiency. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a biomass fuel heating system to solve the problem in the prior art of low combustion efficiency caused by insufficient mixing of cracking gas and oxidizing gas or oxidizing gas.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions.

[0006] The present invention provides a biomass fuel heating system, comprising a cracking gas inlet pipe, a combustion cavity and a flue gas outlet pipe connected in sequence along the flow direction of the biomass cracking gas;

[0007] The combustion chamber is provided with an expanded diameter cone and a swirl blade coaxially arranged with the combustion chamber. There is a gap between the outer wall of the expanded diameter cone and the inner wall of the combustion chamber. The swirl blade is sleeved on the outer wall of the expanded diameter cone. The inner end of the swirl blade is fixedly connected to the expanded diameter cone. The outer end of the swirl blade is fixedly connected to the inner wall of the combustion chamber. The swirl blade is located in the gap between the outer wall of the expanded diameter cone and the inner wall of the combustion chamber. A plurality of swirl air holes are respectively provided on the side walls of the combustion chamber, and the oxidizing gas is supplied into the combustion chamber through the swirl air holes.

[0008] Furthermore, the biomass fuel heating system also includes an air supply outer cavity, and the combustion inner cavity is arranged in the air supply outer cavity and is coaxially fixedly connected to the air supply outer cavity.

[0009] Furthermore, an oxidation gas supply port is provided on the side wall of the air supply outer cavity, and a gap is provided between the combustion inner cavity and the air supply outer cavity.

[0010] Furthermore, the air supply outer cavity is a constant diameter cylinder structure.

[0011] Furthermore, the biomass fuel heating system also includes an igniter, and an ignition end of the igniter extends into the combustion cavity.

[0012] Furthermore, the air outlet direction of the swirl air hole is arranged along the tangential direction of the side wall of the combustion cavity.

[0013] Furthermore, the gas outlet direction of the swirl air hole is inclined away from the cracked gas inlet pipe.

[0014] Furthermore, the cracking gas inlet pipe and the flue gas outlet pipe are constant diameter pipes.

[0015] Furthermore, the combustion cavity includes an expanding section and a reducing section connected in sequence along the flow direction of the biomass cracking gas. The expanding cone and the swirl blades are both arranged in the expanding section. The swirl air holes are arranged on the side wall of the expanding section and are located on the side of the swirl blade away from the cracking gas inlet pipe.

[0016] Furthermore, the swirl directions of the swirl air holes and the swirl blades are the same.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0018] A) The biomass fuel heating system provided by the present invention has dual swirls (i.e., a cracked gas swirl and an oxidizing gas swirl), which can achieve multi-stage swirl distribution, optimize air distribution, and form cracked gas swirls and oxidizing gas swirls. This can significantly extend the mixing time and mixing path of the cracked gas and oxidizing gas in the combustion chamber, thereby improving the mixing uniformity and sufficiency of the two gases, promoting their full combustion, increasing the heat generated by the cracked gas combustion, and achieving full utilization of the biomass fuel (i.e., cracked gas).

[0019] B) The biomass fuel heating system provided by the present invention has an expanded cone with its large end facing the flame direction, which can also block the flame and prevent the flame from flowing back to the other layer of the expanded cone, thereby ensuring the combustion safety of the preheating burner and the carbonization gas burner.

[0020] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages will become apparent from the description or be understood through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the embodiments of the description and the contents particularly pointed out in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0022] Figure 1 A schematic structural diagram of a biomass fuel heating system provided in Example 1 of the present invention;

[0023] Figure 2A schematic structural diagram of a scattering tube in a biomass fuel heating system provided in Example 1 of the present invention;

[0024] Figure 3 This is a structural schematic diagram of the carbonization component pipe in the biomass fuel heating system provided in Example 1 of the present invention.

[0025] Reference numerals:

[0026] 1- cracking gas inlet pipe; 2- combustion inner cavity; 3- gas supply outer cavity; 4- flue gas outlet pipe; 5- igniter; 6- expanded diameter cone; 7- swirl blade; 8- oxidation gas air supply port; 9- swirl air hole; 10- carbonization assembly; 11- plane bottom wall; 12- first diameter reduction wall; 13- second diameter reduction wall; 14- third diameter reduction wall; 15- constant diameter wall; 16- cooling drive wheel; 17- driver; 18- speed regulator; 19- driving wheel; 20- transmission belt; 21- driven wheel; 22- total driving gear; 23- first synchronous belt; 24- second synchronous belt; 25- third synchronous belt; 26- fourth synchronous belt; 27- first drive wheel; 28- second drive wheel; 29- third drive wheel; 30- fourth drive wheel; 31- interlocking wheel; 32- cooling synchronous belt; 33- central gas supply pipe group. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0028] Example 1

[0029] This embodiment provides a biomass fuel heating system. Figure 1 , including a cracking gas inlet pipe 1, a combustion cavity 2 and a flue gas outlet pipe 4 connected in sequence along the flow direction of the biomass cracking gas, the combustion cavity 2 is provided with an expanded diameter cone 6 and a swirl blade 7 coaxially arranged with the combustion cavity 2, a gap is provided between the outer wall of the expanded diameter cone 6 and the inner wall of the combustion cavity 2, the swirl blade 7 is sleeved on the outer wall of the expanded diameter cone 6, the inner end of the swirl blade 7 is fixedly connected to the expanded diameter cone 6, the outer end of the swirl blade 7 is fixedly connected to the inner wall of the combustion cavity 2, the swirl blade 7 is located in the gap between the outer wall of the expanded diameter cone 6 and the inner wall of the combustion cavity 2, and a plurality of swirl air holes 9 are respectively provided on the side walls of the combustion cavity 2, and an oxidizing gas (for example, oxygen or air) is supplied into the combustion cavity 2 through the swirl air holes 9.

[0030] Compared with the prior art, the biomass fuel heating system provided in this embodiment has two swirls (i.e., cracked gas cyclone flow and oxidizing gas cyclone flow), which can realize multi-stage cyclone distribution, optimize air distribution, and form cracked gas cyclone flow and oxidizing gas cyclone flow. It can greatly extend the mixing time and mixing path of cracked gas and oxidizing gas in the combustion cavity 2, thereby improving the mixing uniformity and mixing adequacy of the two, promoting the full combustion of the two, increasing the heat generated by the combustion of cracked gas, and realizing the full utilization of biomass fuel (i.e., cracked gas).

[0031] It should be noted that the arrangement of the expanded diameter cone 6 with the large end facing the flame direction can also block the flame and prevent the flame from flowing back to another layer of the expanded diameter cone 6, thereby ensuring combustion safety.

[0032] It should be noted that the high-temperature flue gas generated by the above-mentioned biomass fuel heating system can be used for its own heating, and can also be used as heating for other heat-demanding systems.

[0033] To facilitate the supply of oxidizing gas, the biomass fuel heating system further includes an external air supply chamber 3. The combustion chamber 2 is disposed within and coaxially fixedly connected to the external air supply chamber 3. An oxidizing gas air inlet 8 (oxidizing gas inlet) is defined on the sidewall of the external air supply chamber 3. A gap is defined between the combustion chamber 2 and the external air supply chamber 3. The oxidizing gas air inlet 8, the gap between the combustion chamber 2 and the external air supply chamber 3, and the swirl air holes 9 form a cyclonic passage for the oxidizing gas. The nesting of the combustion chamber 2 and the external air supply chamber 3 allows for the simultaneous supply and thorough mixing of the two gases, effectively improving the structural compactness of the biomass fuel heating system.

[0034] It is understandable that, in order to ignite the cracking gas and the oxidizing gas, the biomass fuel heating system further includes an igniter 5 , and the ignition end of the igniter 5 extends into the combustion cavity 2 .

[0035] In order to further promote the swirl of the oxidizing gas and provide the cracking gas and oxidizing gas to flow toward the flue gas outlet pipe 4, for example, the outlet direction of the swirl air hole 9 is arranged along the tangent direction of the side wall of the combustion cavity 2 and is inclined away from the cracking gas inlet pipe 1.

[0036] Exemplarily, the air supply outer cavity 3 is a constant diameter cylinder structure, the cracking gas inlet pipe 1 and the flue gas outlet pipe 4 are constant diameter pipes, the combustion inner cavity 2 includes an expansion section and a reduction section connected in sequence along the flow direction of the biomass cracking gas, the expansion cone 6 and the swirl blade 7 are both arranged in the expansion section, the swirl air hole 9 is arranged on the side wall of the expansion section, and is located on the side of the swirl blade 7 away from the cracking gas inlet pipe 1, and the igniter 5 is located on the side of the swirl blade 7 away from the cracking gas inlet pipe 1.

[0037] In this way, on the one hand, due to the setting of the expanded diameter section and the fact that the air supply outer cavity 3 is a constant diameter section, when the oxidizing gas is supplied into the gap between the combustion inner cavity 2 and the air supply outer cavity 3 from the oxidizing gas air supply port 8, the cross-section of the gap gradually decreases, so that the flow rate of the oxidizing gas continues to increase, and flows through the swirl air holes 9 to form a high-speed swirl of oxidizing gas and is supplied to the air supply outer cavity 3; on the other hand, due to the setting of the expanded diameter cone 6, the flow cross-section of the cracking gas can also be reduced, the flow rate of the cracking gas can be increased, and the increase in flow resistance caused by the setting of the swirl blades 7 can be reduced, so that the cracking gas can flow smoothly through the swirl blades 7.

[0038] In summary, the use of a specific structure of the air supply outer chamber 3 and the combustion inner chamber 2, as well as the specific positions of the various components, can increase the flow rate of the oxidizing gas and the flow rate of the cracking gas on the basis of realizing the nested structure of the air supply outer chamber 3 and the combustion inner chamber 2, thereby forming two high-speed vortices and achieving sufficient mixing of the oxidizing gas and the cracking gas.

[0039] It is worth noting that due to the generation of two high-speed vortexes, the air pressure in the combustion cavity 2 near the axis may be reduced, and the concentrations of cracked gas and oxidizing gas here are low, affecting the combustion uniformity in the combustion cavity 2. Therefore, the above-mentioned biomass fuel heating system also includes a double-helix central air supply pipe group 33. Specifically, the central air supply pipe group 33 is located in the combustion cavity 2 and is coaxially arranged with the combustion cavity 2. The central air supply pipe group 33 includes a spiral cracked gas supply pipe and a spiral air supply pipe, which are intertwined to form a double-helix structure. A plurality of cracked gas nozzles are provided on the cracked gas supply pipe, and the gas outlet direction of the cracked gas nozzle is perpendicular to the side wall of the cracked gas supply pipe. A plurality of oxidizing gas nozzles are provided on the oxidizing gas supply pipe, and the gas outlet direction of the oxidizing gas nozzle is perpendicular to the side wall of the oxidizing gas supply pipe. The cracked gas ejected from the cracked gas nozzle has the same swirl direction as the cracked gas flowing out of the swirl blade 7, and the oxidizing gas ejected from the oxidizing gas nozzle has the same swirl direction as the supply gas flowing out of the swirl air hole 9. In this way, the double-helix central air supply pipe group 33 can effectively compensate for the problem of low concentration of cracking gas and oxidizing gas in the central area, improve the uniformity of combustion, and at the same time, the cracking gas ejected from the cracking gas nozzle and the oxidizing gas ejected from the oxidizing gas nozzle are still two swirls, further improving the overall swirl of the airflow in the combustion cavity 2.

[0040] In order to further enhance the cyclone effect and promote the uniformity of mixing of the cracked gas and the oxidizing gas, the swirl directions of the swirl holes 9 and the swirl blades 7 are the same.

[0041] Based on the structure of the above biomass fuel heating system, the flow and mixing process of cracking gas and oxidizing gas is as follows:

[0042] The cracked gas is supplied into the expanded diameter section through the cracked gas inlet pipe 1. In the expanded diameter section, when it passes through the swirl blades 7, a swirl flow is generated to form swirl cracked gas.

[0043] The oxidizing gas is sequentially supplied into the expanded diameter section through the oxidizing gas air supply port 8, the gap between the combustion inner chamber 2 and the air supply outer chamber 3, and the swirl air hole 9, generating a swirl flow to form a swirling oxidizing gas;

[0044] In the expanded diameter section, the swirling cracking gas and the swirling oxidizing gas swirl synchronously and are fully mixed. The igniter 5 ignites the mixed gas, and the cracking gas burns to generate high-temperature flue gas.

[0045] To ensure the supply of cracked gas, the biomass fuel heating system further includes a carbonization assembly, a carbonization furnace, a heat storage buffer tank, a cyclone separator, and an exhaust dust removal box. The carbonization assembly is located within the carbonization furnace. The carbonization gas outlet of the carbonization assembly and the carbonization gas outlet of the cooling auger are both connected to the combustion chamber 2 and the heat storage buffer tank in sequence. The flue gas outlet of the heat storage buffer tank is connected to the air inlet of the carbonization furnace. The exhaust gas outlet of the carbonization furnace is connected to the cyclone separator and the exhaust dust removal box in sequence.

[0046] The carbonization assembly divides the interior of the carbonization furnace into an upper furnace chamber and a lower furnace chamber from top to bottom. The flue gas outlet of the heat storage buffer tank is connected to the lower furnace chamber via a scattering tube. As the biomass moves through the carbonization assembly, the high-temperature flue gas in the heat storage buffer tank is fed into the lower furnace chamber through the scattering tube. The high-temperature flue gas heats the biomass in the carbonization assembly, carbonizing it. The low-temperature flue gas, after heat exchange with the biomass, enters the upper furnace chamber and is discharged through the exhaust gas collection pipe. It then enters the subsequent cyclone separator and exhaust dust box for dust removal and purification.

[0047] For the structure of the scattering tube, see Figure 2 The scattering tube comprises a planar bottom wall 11 and a first, second, third, and constant diameter wall 15, which are arranged on and sequentially connected to the planar bottom wall 11. The planar bottom wall 11, the first, second, third, and constant diameter wall 15 form a tubular structure composed of multiple sections of eccentric reducers. Each of the first, second, third, and constant diameter wall 15 has scattering holes. The end of the first scattering wall 12 away from the second scattering wall 13 serves as the air inlet end of the scattering tube. This scattering tube structure ensures uniform flue gas supply, thereby improving the uniformity of biomass carbonization.

[0048] For carbonized components, see Figure 3It includes a plurality of carbonizing auger pipes arranged in parallel, the carbonizing auger pipe includes a carbonizing pipe body and carbonizing auger blades and a carbonizing rotating shaft arranged in the carbonizing pipe body. The carbonizing auger blades are sleeved on the outer wall of the carbonizing rotating shaft. In two adjacent carbonizing auger pipes, the discharge port of the upper carbonizing pipe body is connected to the feed port of the lower carbonizing pipe body. That is to say, a plurality of carbonizing pipe bodies are connected end to end to form a zigzag biomass conveying pipeline; the spiral directions of the two adjacent carbonizing auger blades are opposite, and the carbonizing auger blades are driven to rotate by the carbonizing rotating shaft to realize the conveying of biomass. A plurality of carbonizing augers are arranged in parallel, and the spiral directions of the blades of two adjacent carbonizing augers are opposite, so that the multi-return movement of the biomass can be realized. The biomass can exchange heat with the high-temperature flue gas multiple times, thereby extending the heat exchange time between the biomass and the high-temperature flue gas, thereby extending the carbonization time of the biomass, improving the heat transfer efficiency, reducing the energy consumption cost, and improving the carbonization efficiency and carbonization quality of the biomass; at the same time, since a plurality of carbonizing augers are arranged in parallel, on the basis of extending the carbonization path, the overall length and installation space of the carbonization component can also be reduced.

[0049] In order to cool the biomass after carbonization, the above-mentioned biomass carbonization component also includes a cooling auger pipe, which is arranged parallel to and in parallel with the carbonizing auger pipe. The cooling auger pipe includes a cooling pipe body and cooling auger blades and a cooling shaft arranged in the cooling pipe body. The cooling auger blades are sleeved on the outer wall of the cooling shaft. The feed end of the cooling pipe body is connected to the discharge end of the last carbonizing pipe body. The spiral direction of the cooling auger blades is opposite to the spiral direction of the last carbonizing auger blade. The carbonized biomass is cooled by the cooling auger pipe.

[0050] In order to simplify the structure of the carbonization assembly and realize the rotation of multiple carbonization shafts and cooling shafts, the above-mentioned biomass carbonization assembly also includes a driving assembly for driving the multiple carbonization shafts and cooling shafts to rotate synchronously.

[0051] Specifically, the drive assembly includes a driver 17, a speed regulator 18, and a synchronous pulley. The output shaft of the driver 17 is connected to the input end of the synchronous pulley through the speed regulator 18, and the output end of the synchronous pulley is respectively connected to multiple carbonizing shafts and cooling shafts. In this way, the driver 17 drives the multiple carbonizing shafts and cooling shafts to rotate synchronously through the speed regulator 18 and the synchronous pulley, thereby realizing the transportation of biomass in the carbonizing assembly.

[0052] In order to realize the connection between the driver 17 and the speed regulator 18, the above-mentioned drive assembly also includes a driving wheel 19, a transmission belt 20 and a driven wheel 21. The driving wheel 19 is coaxially fixedly connected to the output shaft of the driver 17, and the driven wheel 21 is coaxially fixedly connected to the input shaft of the speed regulator 18. One end of the transmission belt 20 is sleeved on the outer wall of the driving wheel 19, and the other end of the transmission belt 20 is sleeved on the outer wall of the driven wheel 21.

[0053] There are four carbonized auger tubes, namely the first carbonized auger tube, the second carbonized auger tube, the third carbonized auger tube and the fourth carbonized auger tube. The first carbonized auger tube includes a first carbonized tube body, a first carbonized auger blade and a first carbonized rotating shaft. The second carbonized auger tube includes a second carbonized tube body, a second carbonized auger blade and a second carbonized rotating shaft. The third carbonized auger tube includes a third carbonized tube body, a third carbonized auger blade and a third carbonized rotating shaft. The fourth carbonized auger tube includes a fourth carbonized tube body, a fourth carbonized auger blade and a fourth carbonized rotating shaft.

[0054] As for the structure of the synchronous pulley, specifically, it includes a total driving gear 22, a first synchronous belt 23, a second synchronous belt 24, a third synchronous belt 25, a fourth synchronous belt 26, a first driving wheel 27, a second driving wheel 28, a third driving wheel 29, a fourth driving wheel 30, a linkage wheel 31, a cooling synchronous belt 32 and a cooling driving wheel 16. The first driving wheel 27 is coaxially fixedly connected to one end of the first carbonization shaft, the second driving wheel 28 is coaxially fixedly connected to one end of the second carbonization shaft, the third driving wheel 29 is coaxially fixedly connected to one end of the third carbonization shaft, the fourth driving wheel 30 is coaxially fixedly connected to one end of the fourth carbonization shaft, the linkage wheel 31 is coaxially fixedly connected to the other end of the fourth carbonization shaft, and the cooling driving wheel 16 is coaxially fixedly connected to one end of the cooling shaft.

[0055] The total driving gear 22 is coaxially fixedly connected to the output shaft of the speed regulator 18. One end of the second synchronous belt 24 and one end of the third synchronous belt 25 are both sleeved on the outer wall of the total driving gear 22. The other end of the second synchronous belt 24 is sleeved on the outer wall of the second drive wheel 28. The other end of the third synchronous belt 25 is sleeved on the outer wall of the third drive wheel. One end of the first synchronous belt 23 is sleeved on the outer wall of the second drive wheel. The other end of the first synchronous belt 23 is sleeved on the outer wall of the first drive wheel. One end of the fourth synchronous belt 26 is sleeved on the outer wall of the third drive wheel. The other end of the four synchronous belts 26 is sleeved on the outer wall of the fourth driving wheel 30, one end of the cooling synchronous belt 32 is sleeved on the outer wall of the linkage wheel 31, and the other end of the cooling synchronous belt 32 is sleeved on the outer wall of the cooling driving wheel 16. With this structure, a driver 17 is used to realize the synchronous rotation of the first carbonized auger pipe, the second carbonized auger pipe, the third carbonized auger pipe, the fourth carbonized auger pipe and the cooling auger pipe, which can effectively improve the structural compactness and transmission efficiency of the drive component, reduce the number of power units, and reduce costs and maintenance difficulties.

[0056] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A biomass fuel heating system, characterized in that: It includes a cracking gas inlet pipe, a combustion cavity and a flue gas outlet pipe which are sequentially connected along the flow direction of the biomass cracking gas; The combustion cavity is provided with an expanding cone and a swirl blade coaxially arranged with the combustion cavity. There is a gap between the outer wall of the expanding cone and the inner wall of the combustion cavity. The swirl blade is sleeved on the outer wall of the expanding cone. The inner end of the swirl blade is fixedly connected to the expanding cone. The outer end of the swirl blade is fixedly connected to the inner wall of the combustion cavity. The swirl blade is located in the gap between the outer wall of the expanding cone and the inner wall of the combustion cavity. A plurality of swirl air holes are respectively provided on the side walls of the combustion cavity, and the oxidizing gas is supplied into the combustion cavity through the swirl air holes.

2. The biomass fuel heating system according to claim 1, characterized in that: The biomass fuel heating system further comprises an air supply outer cavity, and the combustion inner cavity is arranged in the air supply outer cavity and is coaxially fixedly connected to the air supply outer cavity.

3. The biomass fuel heating system according to claim 2, characterized in that: An oxidizing gas supply port is provided on the side wall of the air supply outer cavity, and a gap is provided between the combustion inner cavity and the air supply outer cavity.

4. The biomass fuel heating system according to claim 2, characterized in that: The air supply outer cavity is a constant diameter cylinder structure.

5. The biomass fuel heating system according to claim 1, characterized in that: The biomass fuel heating system further comprises an igniter, wherein an ignition end of the igniter extends into the combustion cavity.

6. The biomass fuel heating system according to claim 1, characterized in that: The air outlet direction of the swirl air hole is arranged along the tangent direction of the side wall of the combustion cavity.

7. The biomass fuel heating system according to claim 6, characterized in that: The gas outlet direction of the swirl air hole is inclined away from the direction of the cracked gas inlet pipe.

8. The biomass fuel heating system according to claim 1, characterized in that: The cracking gas inlet pipe and the flue gas outlet pipe are constant diameter pipes.

9. The biomass fuel heating system according to claim 1, characterized in that: The combustion cavity includes an expanding diameter section and a reducing diameter section connected in sequence along the flow direction of the biomass cracking gas. The expanding diameter cone and the swirl blades are both arranged in the expanding diameter section. The swirl air holes are arranged on the side wall of the expanding diameter section and are located on the side of the swirl blade away from the cracking gas inlet pipe.

10. The biomass fuel heating system according to any one of claims 1 to 9, characterized in that: The swirl directions of the swirl air holes and the swirl blades are the same.

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