Floating type semi-fluidized combustion wns biomass steam boiler

Abstract

The invention relates to the technical field of steam boilers, in particular to a floating type semi-fluidized combustion wns biomass steam boiler. Comprising a container room and a horizontal internal combustion boiler body arranged in the container room, and the horizontal internal combustion boiler body comprises a boiler cavity and a combustion mechanism arranged below the boiler cavity. The combustion mechanism comprises a boiler cavity and a floating type semi-fluidized combustion assembly arranged in the boiler cavity, a multi-pass smoke return structure is arranged at the bottom end of the boiler cavity, and high-temperature smoke in the boiler cavity is exhausted outwards after passing through the multi-pass smoke return structure. The floating type semi-fluidized combustion assembly comprises a fluidized bed formed by pouring high-temperature-resistant castable, a channel is vertically arranged on the fluidized bed, a hood is arranged at the top end of the channel, and materials above the fluidized bed are in a semi-fluidized state through cooperation of a material spreading mechanism and a high-pressure cavity. The integration degree is high, the burn-off rate of fuel is high, and the heat efficiency of the boiler is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of steam boilers, and in particular to a floating type semi-fluidized combustion WNS biomass steam boiler. Background Art

[0002] WNS biomass steam boiler is a horizontal internal combustion steam boiler that uses biomass pellet fuel as heat source. It has the characteristics of high efficiency, energy saving, environmental protection, economy and compact structure.

[0003] At present, in order to achieve the effective combustion of biomass pellet fuel, most of these furnace types are equipped with large grate structures or added outdoor combustion structures. Large grate structures are generally composed of multiple grate plates, and the fuel is transported, stirred, and burned through the reciprocating motion or vibration of the grate. Although this structure can ensure the full combustion of the fuel, it is complex and requires a large amount of metal materials and precise mechanical transmission devices, resulting in high manufacturing costs. Adding an outdoor combustion structure requires the construction of additional combustion equipment outside the boiler room, which not only increases the floor space, but also requires consideration of issues such as connection and sealing with the boiler body, further increasing construction and maintenance costs.

[0004] Patent document CN207113237U discloses a horizontal, internal combustion, three-pass wetback gas-fired boiler with a test tube. It comprises a cylindrical boiler shell arranged horizontally and longitudinally, with a furnace core positioned in the lower middle portion of the shell's interior. The furnace core is cylindrical in shape. Burners are located externally on the furnace core. External burners increase structural complexity and ultimately make the boiler excessively large, increasing production costs and boiler room infrastructure investment. Furthermore, they cause a certain amount of heat loss, reducing thermal efficiency. Summary of the Invention

[0005] The present invention provides a floating semi-fluidized combustion WNS biomass steam boiler to solve the technical problems in the prior art that the external burner of the steam boiler increases the boiler production cost and boiler room infrastructure investment and reduces the thermal efficiency.

[0006] In order to solve the above problems, the present invention provides a floating type semi-fluidized combustion WNS biomass steam boiler adopts the following technical solutions: The utility model comprises a container house and a horizontal internal combustion boiler body arranged in the container house. The horizontal internal combustion boiler body comprises a boiler cavity and a combustion mechanism arranged below the boiler cavity.

[0007] The combustion mechanism includes a furnace cavity and a floating semi-fluidized combustion component arranged in the furnace cavity. The bottom end of the boiler cavity is provided with a multi-pass smoke return structure, and the high-temperature smoke in the furnace cavity is discharged to the outside after passing through the multi-pass smoke return structure.

[0008] The floating semi-fluidized combustion assembly includes a fluidized bed formed by casting high-temperature resistant castable material, a channel is vertically provided on the fluidized bed, a wind hood is provided at the top of the channel, a high-pressure chamber is formed at the bottom of the fluidized bed, and a feeding mechanism for feeding material above the fluidized bed is provided outside the furnace cavity. The material above the fluidized bed is in a semi-fluidized state through the cooperation of the feeding mechanism and the high-pressure chamber.

[0009] Furthermore, a front smoke box is provided at the front end of the boiler cavity, a rear smoke box is provided at the rear end of the boiler cavity, and a backfire chamber is formed at one end of the furnace cavity close to the rear smoke box.

[0010] The multi-pass smoke return structure includes a first smoke tube bundle connected between the front smoke box and the backfire chamber and a second smoke tube bundle connected between the front smoke box and the rear smoke box. The first smoke tube bundle and the second smoke tube bundle are both arranged at the bottom of the boiler cavity.

[0011] Furthermore, a furnace door is provided at the front end of the furnace cavity, the reburning chamber is provided at one end of the furnace cavity away from the furnace door, a flat furnace rib is provided in the furnace cavity near the furnace door, a corrugated furnace rib is formed between the flat furnace rib and the reburning chamber, and the combustion mechanism is provided in the flat furnace rib.

[0012] The bottoms of the reburning chamber and the corrugated furnace are both provided with air supply pipe openings.

[0013] Furthermore, a high-temperature resistant baffle is provided between the straight furnace core and the corrugated furnace core, and an overflow gap is formed between the top end of the high-temperature resistant baffle and the top wall of the furnace cavity.

[0014] Furthermore, a refractory partition is provided on the top of the flat furnace.

[0015] Furthermore, the hood is provided with an asymmetric opening, which is inclined downward from the middle to the edge of the hood, and the angle between the axis of the opening and the horizontal plane is 15°-45°, and the diameter of the opening is 3-5mm.

[0016] Furthermore, the material feeding mechanism includes a hopper, and a material feeding air duct is provided between the hopper and the fluidized bed. The end of the material feeding air duct away from the hopper passes through the fluidized bed, and the length of the material feeding air duct extending upward from the fluidized bed is less than the distance between the top of the wind cap and the fluidized bed.

[0017] A blower for blowing air into the material broadcasting air duct is provided on one side of the hopper.

[0018] Furthermore, an energy saver is provided on the side of the rear smoke box, the smoke outlet of the energy saver is connected to a dust collector through a pipe, an induced draft fan is provided on the pipe between the energy saver and the dust collector, and the outlet of the dust collector is externally connected to a high-altitude chimney.

[0019] The beneficial effects of the floating semi-fluidized combustion WNS biomass steam boiler provided by the present invention are: The combustion mechanism in the present invention is directly integrated under the boiler cavity to enhance the heat transfer effect and avoid adding an external combustion structure, which causes the overall structure to occupy a larger space. A channel is vertically provided on the fluidized bed of the floating semi-fluidized combustion assembly in the combustion structure. A wind cap is provided at the top of the channel, and a high-pressure chamber is formed at the bottom. The fan blows air into the high-pressure chamber, causing the biomass particles to continuously roll and disturb on the fluidized bed and fully mix with the air. In specific use, the contact area between the particles and the air increases by 3 times, and the combustion efficiency is increased from 78% to 92%, which effectively improves the burnout rate and reduces the loss of unburned fuel, thereby improving the overall combustion efficiency of the boiler.

[0020] In the present invention, the hood is provided with asymmetric openings, which are inclined downward from the middle of the hood to the edge, with the axis at an angle of 35° to the horizontal plane and a diameter of 3-5 mm. The obliquely downward openings give the blown airflow an impact force downward and in all directions. The asymmetric layout causes the airflow impact direction and force at different positions to differ, thereby enhancing the mixing and collision between particles, causing the biomass particles to tumble and move more fully on the fluidized bed, facilitating the full mixing of fuel and air and improving combustion efficiency. At the same time, the appropriate opening diameter can not only ensure sufficient airflow throughput, but also generate an airflow impact force of sufficient intensity to prevent biomass particles from settling. It can also prevent biomass particles or ash from clogging the openings to a certain extent, thereby ensuring normal ventilation of the hood and normal operation of the fluidized bed.

[0021] In the present invention, air supply pipes are provided at the bottom of the backfire chamber and the corrugated furnace, which can replenish air into the furnace and provide the required oxygen for the incompletely burned high-temperature flue gas, allowing the combustible components in the flue gas to continue to react with oxygen and further release heat. The corrugated furnace provides additional combustion space and time for the incompletely burned flue gas. A high-temperature resistant baffle is provided between the flat furnace and the corrugated furnace, forming a flow gap between its top and the top wall of the furnace chamber. It can adjust the flue gas flow path so that some flue gas has a more appropriate residence time in the flat furnace, ensuring that the fuel has sufficient time to react with oxygen and improving combustion efficiency. The multi-pass flue gas disturbance and intelligent air supply system control the incomplete combustion loss to less than 5%, reducing fuel waste by more than 40% compared to traditional biomass boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an illustrative and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 It is a front view of the floating semi-fluidized combustion WNS biomass steam boiler of the present invention; Figure 2 It is a structural schematic diagram of the combustion mechanism in the present invention; Figure 3 for Figure 2 A partial enlarged view of the middle area A; Figure 4 A top view of the floating semi-fluidized combustion WNS biomass steam boiler of the present invention; Figure 5 It is a side view of the floating semi-fluidized combustion WNS biomass steam boiler of the present invention.

[0023] Description of reference numerals: 1. Container room; 2. Horizontal internal combustion boiler body; 3. Boiler chamber; 31. Front smoke box; 32. Rear smoke box; 33. First smoke tube bundle; 34. Second smoke tube bundle; 4. Combustion mechanism; 41. Furnace chamber; 42. Floating semi-fluidized combustion assembly; 421. Fluidized bed; 4211. Passage; 4212. Wind hood; 4213. Opening; 422. High-pressure chamber; 43. Backdraft chamber; 44. Furnace door; 45. Flat furnace core; 451. Refractory partition; 46. Corrugated furnace core; 47. High-temperature resistant baffle; 5. Material spreading mechanism; 51. Hopper; 52. Material spreading air duct; 53. Blower; 6. Energy saver; 7. Dust collector; 8. Induced draft fan; 9. High-temperature chimney. DETAILED DESCRIPTION

[0024] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0025] Any number of elements in the drawings is for illustration and not limitation, and any naming is for distinction only and does not have any limiting meaning.

[0026] The principles and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0027] An embodiment of a floating semi-fluidized combustion WNS biomass steam boiler provided by the present invention: like Figures 1 to 5 As shown, The horizontal internal combustion boiler body 2 includes a container house 1 and a horizontal internal combustion boiler body 2 arranged in the container house 1. The horizontal internal combustion boiler body 2 includes a boiler cavity 3 and a combustion mechanism 4 arranged below the boiler cavity 3.

[0028] In the above solution, the combustion mechanism 4 is directly integrated under the boiler cavity 3 to enhance the heat transfer effect and avoid adding an external combustion structure, which causes the overall structure to occupy a larger space.

[0029] In this embodiment, the combustion mechanism 4 includes a furnace cavity 41 and a floating semi-fluidized combustion assembly 42 arranged in the furnace cavity 41. The floating semi-fluidized combustion assembly 42 includes a fluidized bed 421 formed by casting high-temperature resistant castable material. A channel 4211 is vertically provided on the fluidized bed 421. A wind hood 4212 is provided at the top of the channel 4211. A high-pressure chamber 422 is formed at the bottom of the fluidized bed 421.

[0030] Specifically, a pipe connected to the outside is provided at the bottom of the high-pressure chamber 422, and the outside of the pipe is connected to a fan. The fan blows air into the high-pressure chamber 422 through the pipe to form a high-pressure area. The wind blown into the high-pressure chamber 422 is blown out through the channel 4211 and the wind cap 4212 at the end, so that the biomass particles in the upper layer of the fluidized bed 421 are in a floating semi-fluidized combustion state.

[0031] The biomass particles are continuously tumbled and disturbed on the fluidized bed 421 and are fully mixed with the air, thereby improving the burnout rate, reducing the loss of unburned fuel, and thus improving the overall combustion efficiency of the boiler.

[0032] In practice, the pressure within high-pressure chamber 422 can be easily adjusted by adjusting the fan's air volume, thereby varying the air velocity and volume exiting hood 4212. Changes in air velocity and volume directly affect the biomass pellet buoyancy and combustion intensity. In actual operation, combustion intensity can be flexibly adjusted based on the boiler's load requirements, ensuring efficient boiler operation.

[0033] The hood 4212 is provided with an asymmetric opening 4213, which is inclined downward from the middle to the edge of the hood 4212, and the angle α between the axis of the opening 4213 and the horizontal plane is 35°, and the diameter of the opening 4213 is 3-5 mm.

[0034] The downwardly angled openings 4213 impart downward and all-around impact to the airflow, effectively disturbing the biomass particles on the fluidized bed 421. The asymmetric layout of openings 4213 results in different airflow impact directions and forces at different locations, further enhancing mixing and collision between particles. This allows the biomass particles to tumble and move more fully on the fluidized bed 421, promoting sufficient mixing of fuel and air and improving combustion efficiency.

[0035] The openings 4213, with a diameter of 3-5 mm, are of a moderate size, ensuring sufficient airflow while generating sufficient airflow impact to prevent biomass particles from settling near the hood or in certain areas of the fluidized bed. A smaller opening diameter increases the velocity and pressure of the airflow, making it easier for particles to be lifted and kept suspended, thus avoiding problems such as uneven combustion and localized slagging caused by particle deposition.

[0036] Additionally, the openings 4213, with a diameter of 3-5 mm, can prevent biomass particles or ash from clogging the openings to a certain extent. The smaller opening diameter can prevent larger particles from entering, while the downwardly inclined design also facilitates the discharge of particles and ash, reducing the possibility of clogging and ensuring proper ventilation of the hood and normal operation of the fluidized bed.

[0037] In this embodiment, a multi-pass smoke return structure is provided at the bottom end of the boiler cavity 3 , and the high-temperature smoke in the furnace cavity 41 is discharged to the outside after passing through the multi-pass smoke return structure.

[0038] A front smoke box 31 is provided at the front end of the boiler cavity 3 , a rear smoke box 32 is provided at the rear end of the boiler cavity 3 , and a backfire chamber 43 is formed at one end of the furnace cavity 41 close to the rear smoke box 32 .

[0039] The multi-pass smoke return structure includes a first smoke tube bundle 33 connected between the front smoke box 31 and the backfire chamber 43 and a second smoke tube bundle 34 connected between the front smoke box 31 and the rear smoke box 32. The first smoke tube bundle 33 and the second smoke tube bundle 34 are both arranged at the bottom of the boiler cavity 3.

[0040] During operation, the high-temperature flue gas within the backfire chamber 43 passes through the first flue tube bundle 33 and enters the front flue box 31. It should be noted that a refractory lining is provided on the side of the front flue box 31 opposite the port of the first flue tube bundle 33 to prevent the high-temperature flue gas from eroding or damaging the inner wall of the front flue box 31. High-temperature flue gas is highly corrosive and abrasive, and the refractory lining can withstand the impact of the high temperature and flue gas, extending the service life of the front flue box and reducing boiler maintenance costs.

[0041] The flue gas after heat exchange in the first flue tube bundle 33 enters the front flue box 31 and then passes through the second flue tube bundle 34 for further heat exchange before entering the rear flue box 32 .

[0042] The multi-pass smoke recirculation structure, through the provision of a first smoke tube bundle 33 and a second smoke tube bundle 34, allows the high-temperature flue gas to undergo a longer process within the boiler chamber 3. The flue gas first enters the first smoke tube bundle 33 from the rewind chamber 43, then passes to the front smoke box 31, and then enters the rear smoke box 32 through the second smoke tube bundle 34. This significantly increases the heat exchange time and area between the flue gas and the boiler water.

[0043] Specifically, the first smoke tube bundle 33 and the second smoke tube bundle 34 are corrugated tubes.

[0044] Among them, an energy saver 6 is provided on the side of the rear smoke box 32, and the smoke outlet of the energy saver 6 is connected to the dust collector 7 through a pipe. An induced draft fan 8 is provided on the pipe between the energy saver 6 and the dust collector 7, and the outlet of the dust collector 7 is connected to the high-altitude chimney 9 to the outside.

[0045] The high-temperature flue gas in the rear smoke box 32 recovers waste heat through the economizer 6, is dust-removed by the dust collector 7, and is discharged to the outside through the high-altitude chimney 9.

[0046] In this embodiment, a furnace door 44 is provided at the front end of the furnace cavity 41, and a reburning chamber 43 is provided at one end of the furnace cavity 41 away from the furnace door 44. A flat furnace rib 45 is provided near the furnace door 44 in the furnace cavity 41, and a corrugated furnace rib 46 is formed between the flat furnace rib 45 and the reburning chamber 43. The combustion mechanism 4 is provided in the flat furnace rib 45.

[0047] The bottoms of the backfire chamber 43 and the corrugated furnace 46 are both provided with air supply pipe openings.

[0048] The air supply pipes provided at the bottom of the backfire chamber 43 and the corrugated furnace 46 replenish air into the furnace, providing oxygen to the incompletely burned high-temperature flue gas. Incompletely burned flue gas typically contains combustible components such as carbon monoxide and hydrocarbons. After oxygen is added, these combustible components will continue to react with the oxygen, further releasing heat and improving combustion efficiency.

[0049] The corrugated furnace 46, located between the straight furnace 45 and the backfire chamber 43, provides additional combustion space and time for incompletely burned flue gas. As the flue gas flows through the corrugated furnace 46, it has ample time to fully mix with the supplemental oxygen and complete the combustion reaction, effectively utilizing the combustible materials in the fuel.

[0050] A high-temperature resistant baffle 47 is provided between the flat furnace core 45 and the corrugated furnace core 46 , and an overflow gap is formed between the top end of the high-temperature resistant baffle 47 and the top wall of the furnace chamber 41 .

[0051] The existence of the overflow gap allows the flue gas to pass through the space between the top of the baffle 47 and the top wall of the furnace chamber 41, forming a "bypass" channel. Appropriate flue gas residence time is one of the key factors to ensure sufficient combustion. The overflow gap can indirectly affect the residence time of the flue gas in the flat furnace 45. If all the flue gas enters the corrugated furnace 46 directly from the flat furnace 45, it may cause some of the flue gas to stay in the flat furnace 45 for too short a time, resulting in incomplete combustion. The "bypass" channel formed by the overflow gap can adjust the flue gas flow path, so that some of the flue gas has a more appropriate residence time in the flat furnace 45, ensuring that the fuel has enough time to react with oxygen and improve combustion efficiency.

[0052] A refractory partition 451 is provided on the top of the flat furnace 45 .

[0053] In this embodiment, a feeding mechanism 5 for feeding material above the fluidized bed 421 is provided outside the furnace chamber 41 . The feeding mechanism 5 and the high-pressure chamber 422 cooperate to keep the material above the fluidized bed 421 in a semi-fluidized state.

[0054] Among them, the material broadcasting mechanism 5 includes a hopper 51, and a material broadcasting air duct 52 is provided between the hopper 51 and the fluidized bed 421. The end of the material broadcasting air duct 52 away from the hopper 51 passes through the fluidized bed 421. The length of the material broadcasting air duct 52 extending upward from the fluidized bed 421 is less than the distance between the top of the wind cap 4212 and the fluidized bed 421.

[0055] A blower 53 for blowing air into the material dispensing air duct 52 is provided on one side of the hopper 51 .

[0056] During specific use, the material enters the material distributing air duct 52 evenly from the hopper 51, and then is blown into the top of the fluidized bed 421 by the blower 53. When the thickness of the material above the fluidized bed 421 reaches 50 mm, the electric heating fire rod is inserted into the material layer from the furnace door 44 for ignition.

[0057] The floating semi-fluidized combustion WNS biomass steam boiler of this embodiment is used in a biomass pellet combustion test. Specifically, the steam boiler has a capacity of 4t / h of steam and a fluidized bed 421 area of ​​2.5m². The fan blows air into the high-pressure chamber 422 at a pressure of 2800Pa. The oblique airflow through the hood 4212 causes the biomass pellets to continuously tumble, forming a 60-80mm dynamic suspension layer. The contact area between the pellets and the air increases by three times, and the combustion efficiency increases from 78% to 92%. The multi-pass flue gas disturbance and intelligent air supply system control incomplete combustion losses to less than 5%, reducing fuel waste by more than 40% compared to traditional biomass boilers.

[0058] Finally, the economizer 6 recovers waste heat to reduce the exhaust gas temperature from 220°C to 140°C, and the thermal efficiency is increased by 6%.

[0059] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "up", "down", "front", "back", "left", "right", "width", "horizontal", "top", "bottom", "inside", "outside" and other terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings of this specification. They are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0060] In addition, in the description of this specification, “a plurality of” means at least two, for example, two, three or more, etc., unless otherwise clearly and specifically defined.

Claims

1. A floating semi-fluidized combustion WNS biomass steam boiler, comprising a container house (1) and a horizontal internal combustion boiler body (2) arranged in the container house (1), characterized in that: The horizontal internal combustion boiler body (2) comprises a boiler cavity (3) and a combustion mechanism (4) arranged below the boiler cavity (3); The combustion mechanism (4) comprises a furnace cavity (41) and a floating semi-fluidized combustion assembly (42) disposed in the furnace cavity (41); a multi-pass smoke return structure is disposed at the bottom end of the boiler cavity (3); and high-temperature smoke in the furnace cavity (41) is discharged to the outside after passing through the multi-pass smoke return structure; The floating semi-fluidized combustion assembly (42) includes a fluidized bed (421) formed by casting a high-temperature resistant castable material, a channel (4211) is vertically provided on the fluidized bed (421), a wind cap (4212) is provided at the top of the channel (4211), a high-pressure chamber (422) is formed at the bottom of the fluidized bed (421), and a material feeding mechanism (5) for feeding material above the fluidized bed (421) is provided outside the furnace chamber (41). The material above the fluidized bed (421) is in a semi-fluidized state through the cooperation of the material feeding mechanism (5) and the high-pressure chamber (422).

2. The floating semi-fluidized combustion biomass steam boiler according to claim 1 is characterized in that: A front smoke box (31) is provided at the front end of the boiler cavity (3), a rear smoke box (32) is provided at the rear end of the boiler cavity (3), and a backfire chamber (43) is formed at one end of the furnace cavity (41) close to the rear smoke box (32); The multi-pass smoke return structure comprises a first smoke tube bundle (33) connected between a front smoke box (31) and a backfire chamber (43), and a second smoke tube bundle (34) connected between the front smoke box (31) and a rear smoke box (32). The first smoke tube bundle (33) and the second smoke tube bundle (34) are both arranged at the bottom of the boiler cavity (3).

3. The floating semi-fluidized combustion biomass steam boiler according to claim 2 is characterized in that: A furnace door (44) is provided at the front end of the furnace cavity (41); the reburning chamber (43) is provided at one end of the furnace cavity (41) away from the furnace door (44); a flat furnace rib (45) is provided near the furnace door (44) in the furnace cavity (41); a corrugated furnace rib (46) is formed between the flat furnace rib (45) and the reburning chamber (43); and the combustion mechanism (4) is provided in the flat furnace rib (45); The bottoms of the reburning chamber (43) and the corrugated furnace (46) are both provided with air supply pipe openings.

4. The floating semi-fluidized combustion biomass steam boiler according to claim 3 is characterized in that: A high-temperature resistant baffle (47) is provided between the straight furnace core (45) and the corrugated furnace core (46), and an overflow gap is formed between the top end of the high-temperature resistant baffle (47) and the top wall of the furnace chamber (41).

5. The floating semi-fluidized combustion biomass steam boiler according to claim 3 is characterized in that: A refractory partition (451) is provided on the top of the flat furnace (45).

6. The floating semi-fluidized combustion biomass steam boiler according to claim 1 is characterized in that: The hood (4212) is provided with an asymmetric opening (4213), the opening (4213) is inclined downward from the middle to the edge of the hood (4212), and the angle between the axis of the opening (4213) and the horizontal plane is 15°-45°, and the diameter of the opening (4213) is 3-5 mm.

7. The floating semi-fluidized combustion biomass steam boiler according to claim 1 is characterized in that: The material broadcasting mechanism (5) includes a hopper (51), a material broadcasting air duct (52) is provided between the hopper (51) and the fluidized bed (421), an end of the material broadcasting air duct (52) away from the hopper (51) penetrates the fluidized bed (421), and a length of the material broadcasting air duct (52) extending upward from the fluidized bed (421) is less than the distance between the top of the air cap (4212) and the fluidized bed (421); A blower (53) for blowing air into the material broadcasting air duct (52) is provided on one side of the hopper (51).

8. The floating semi-fluidized combustion biomass steam boiler according to claim 2 is characterized in that: An energy saver (6) is provided on the side of the rear smoke box (32), and a smoke outlet of the energy saver (6) is connected to a dust collector (7) through a pipeline. An induced draft fan (8) is provided on the pipeline between the energy saver (6) and the dust collector (7), and the outlet of the dust collector (7) is externally connected to a high-altitude chimney (9).

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