A mixing and feeding device for a fluidized bed unit

Abstract

This invention discloses a mixing and feeding device for a fluidized bed boiler, comprising two mixing and feeding mechanisms externally located on two opposite sides of the lower part of the boiler, and two discharging mechanisms respectively located at both ends of the mixing and feeding mechanisms, with each discharging mechanism connected to the same side end of the two mixing and feeding mechanisms. An air supply system is connected to the mixing and feeding mechanisms, the primary air chamber, and the secondary air chamber. This invention eliminates the need for pre-mixing fuels of different particle sizes; simply feeding two fuels of different particle sizes into the mixing and feeding mechanisms achieves fuel mixing. Furthermore, using only two mixing and feeding mechanisms ensures comprehensive fuel supply to the bottom of the boiler furnace, improving boiler efficiency and preventing incomplete combustion that results in excessive harmful gases and tar, while also reducing equipment investment. This invention is applicable to the technical field of fuel, primary air, and secondary air supply for fluidized bed boilers.

Description

Technical Field

[0001] This invention belongs to the technical field of fluidized bed boilers, and more specifically, relates to a mixing and feeding device for a fluidized bed unit. Background Technology

[0002] Fluidized bed boilers are suitable for most thermal power plants due to their high combustion efficiency and relatively flexible fuel requirements. Typically, they use low-grade coal, coal gangue, biomass fuels, and solid waste fuels. To ensure complete combustion, most boilers pre-mix pulverized coal with other large-particle fuels, then supply the mixture to the boiler's feed inlets simultaneously via multiple auger conveyors, allowing it to fall into the bottom of the furnace. Primary air enters the primary air chamber at the bottom of the boiler and is then sprayed out through nozzles to provide oxygen for combustion. Therefore, the two different particle sizes of fuel must be pre-mixed before being supplied to the boiler. Without mixing, incomplete combustion occurs, resulting in more harmful gases and tar. Furthermore, multiple auger conveyors are required, leading to a relatively large investment and a higher failure rate. Summary of the Invention

[0003] This invention provides a mixing and feeding device for a fluidized bed unit. It eliminates the need for pre-mixing fuels of different particle sizes. Simply feed two different particle sizes of fuel into the mixing and feeding mechanism to achieve mixing between the fuels. Furthermore, only two mixing and feeding mechanisms are needed to ensure fuel supply to the bottom of the boiler furnace without dead zones, thereby improving boiler efficiency, avoiding incomplete combustion that would result in excessive amounts of harmful gases and tar, and reducing equipment investment.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A mixing and feeding device for a fluidized bed unit includes two mixing and feeding mechanisms externally located on two opposite sides of the lower part of the boiler, two discharging mechanisms respectively located at both ends of the mixing and feeding mechanisms, and each discharging mechanism is connected to the same side end of the two mixing and feeding mechanisms. An air supply system is connected to the mixing and feeding mechanisms, the primary air chamber and the secondary air chamber respectively.

[0006] Furthermore, the mixing and feeding mechanism includes an outer shell fixedly installed on the outer wall of the boiler. The outer shell has a discharge port extending along its axial direction, which is connected to a strip-shaped fuel inlet on the boiler wall. A mixing guide cylinder is rotatably installed inside the outer shell. The mixing guide cylinder is aligned with the axis of the outer shell, forming an inner feeding chamber. An outer feeding mixing chamber is formed between the mixing guide cylinder and the outer shell. A first feed port and a second feed port are respectively constructed at both axial ends of the outer shell. The first feed port is connected to the inner feeding chamber, and the second feed port is connected to the outer feeding mixing chamber. The first feed port and the second feed port are respectively connected to two feeding mechanisms.

[0007] Furthermore, a first spiral guide blade and a second spiral guide blade with opposite directions of rotation are respectively constructed on the inner and outer walls of the guide mixing orifice, and the first spiral guide blade and the second spiral guide blade extend spirally along the axis of the guide mixing orifice.

[0008] Furthermore, the pitch of the first spiral guide blade increases from the first feed port to the second feed port, the pitch of the second spiral guide blade increases from the second feed port to the first feed port, the diameter of the discharge hole on the mixing cylinder is larger than the particle size of the fuel in the inner feeding chamber, and the diameter of the discharge hole is smaller than the particle size of the fuel in the outer feeding mixing chamber, and the height of the discharge port on the outer cylinder shell is 1 / 3-3 / 5 of the outer cylinder shell in the horizontal state.

[0009] Furthermore, a cyclone mixing tube is coaxially installed inside the mixing guide tube. One end of the cyclone mixing tube extends out of the mixing guide tube, and a drive wheel is installed at that end of the cyclone mixing tube. A guide cover is constructed at the other end of the cyclone mixing tube. The guide cover is a trumpet-shaped structure with a gradually narrowing diameter along the axis of the cyclone mixing tube toward the drive wheel. This trumpet-shaped structure is located at the inlet end of the inner feeding chamber.

[0010] Furthermore, a plurality of spiral air outlet holes are uniformly opened along the circumference of the cyclone mixing pipe, each spiral air outlet hole extending spirally along the axis of the cyclone mixing pipe, and the end of the cyclone mixing pipe is connected to the air supply system.

[0011] Furthermore, a secondary air inlet extending into the furnace is provided on the outer shell and above the discharge port. The secondary air inlet extends along the axial direction of the outer shell to both ends of the outer shell, and the diameter of the secondary air inlet gradually decreases along the direction of air flow.

[0012] Furthermore, the feeding mechanism includes a feeding cylinder with a connecting joint at the upper end, and two guide pipes connected to the lower end of the feeding cylinder. Each guide pipe is connected to the end of a corresponding mixing and feeding mechanism. Multiple rotating blades are uniformly arranged along the circumference inside the feeding cylinder, and an air inlet joint is arranged at the upper part of the feeding cylinder. The air inlet joint is connected to an air supply system.

[0013] Furthermore, the air supply system includes two air inlet branch pipes connected to the main air inlet pipe. The two air inlet branch pipes are respectively located on two opposite sides of the boiler. Each air inlet branch pipe is connected to the primary air chamber through the primary air inlet at the bottom of the boiler. Each air inlet branch pipe is connected to a first connecting pipe. Each first connecting pipe is connected to the corresponding mixing and feeding mechanism. The air inlet branch pipe is also connected to two feeding mechanisms through two second connecting pipes.

[0014] Furthermore, a hot air duct is provided in the primary air chamber. The hot air duct is connected to two air inlet branch pipes. The air inlet end of one second connecting pipe is connected to the hot air duct, and the other second connecting pipe is connected to the hot air duct through a distribution pipe. The distribution pipe is connected to the mixing and feeding mechanism through two connecting pipes respectively.

[0015] The present invention, by employing the aforementioned structure, achieves a technological advancement compared to existing technologies in the following ways: The present invention feeds two fuels of different particle sizes to two separate feeding mechanisms. These two feeding mechanisms simultaneously supply the two fuels to a mixing feeding mechanism. During operation, the mixing feeding mechanism mixes the two fuels, and the mixed fuel enters the furnace in a parabolic shape. Because the two mixing feeding mechanisms simultaneously supply the mixed fuel to the furnace, the two parabolic surfaces formed by the fuel intersect and mix, gradually falling to the bottom of the furnace. This avoids the problem of fuel accumulation and dead zones at the bottom of the furnace, whereas existing auger conveyors deliver fuel at a single point, making fuel accumulation unavoidable. Therefore, compared to auger conveyors, the mixing feeding mechanism of the present invention ensures that, with sufficient air supply, the fuel burns completely within a predetermined time after entering the furnace, preventing the generation of harmful gases and tar. Furthermore, the air supply system not only supplies primary and secondary air but also promotes fuel mixing in the mixing feeding mechanism and ensures that the fuel enters the furnace in a parabolic shape. This invention can control the secondary air and the pressure gas entering the mixing and feeding mechanism according to the specific combustion conditions, avoiding the loss of calorific value due to low temperature when entering the boiler. In summary, this invention does not require premixing fuels of different particle sizes. It only needs to feed two fuels of different particle sizes into the mixing and feeding mechanism to achieve fuel mixing. Moreover, only two mixing and feeding mechanisms are needed to achieve fuel supply to the bottom of the boiler furnace without dead zones, improving boiler efficiency, avoiding incomplete combustion that results in more harmful gases and tar, and reducing equipment investment. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0017] In the attached diagram:

[0018] Figure 1 This is a schematic diagram of the structure connecting the mixing and feeding mechanism, the unloading mechanism, and the air supply system to the local boiler in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure connecting the mixing and feeding mechanism, the unloading mechanism, and the air supply system to the boiler after the upper part has been removed, according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure connecting the mixing and feeding mechanism, the discharging mechanism, and the air supply system to the boiler after the lower part has been removed, according to an embodiment of the present invention.

[0021] Figure 4 This is a cross-sectional view of the connection between the mixing and feeding mechanism, the discharging mechanism, and the air supply system and the boiler in an embodiment of the present invention.

[0022] Figure 5 This is an axial structural cross-sectional view of the mixing and feeding mechanism according to an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the outer shell of the mixing and feeding mechanism according to an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of the structure of the mixing feed mechanism guide cylinder according to an embodiment of the present invention;

[0025] Figure 8 This is a schematic diagram of the cyclone mixing pipe of the mixing and feeding mechanism in an embodiment of the present invention;

[0026] Figure 9 This is an axial structural cross-sectional view of the feeding mechanism according to an embodiment of the present invention.

[0027] Components labeled: 100-Boiler, 101-Furnace body, 102-Primary air chamber, 103-Primary air inlet, 104-Furnace chamber, 105-Secondary air chamber, 106-Strip fuel inlet, 200-Mixing and feeding mechanism, 201-Outer shell, 202-First feed inlet, 203-Second feed inlet, 204-Discharge outlet, 205-Secondary air inlet, 206-Blocking flange, 207-Guide mixing orifice, 208-Fine material inlet, 209-First spiral guide blade, 210-Second spiral guide blade, 211-Cyclone mixing pipe 212-Spiral air outlet, 213-Guide cover, 214-Drive wheel, 215-Inner feeding chamber, 216-Outer feeding mixing chamber, 300-Discharging mechanism, 301-Discharging cylinder, 302-Connecting joint, 303-Air inlet joint, 304-Spiral blade, 305-Guide pipe, 400-Air supply system, 401-Main air inlet pipe, 402-Branch air inlet pipe, 403-Hot air pipe, 404-First connecting pipe, 405-Hot air duct, 406-Distribution pipe, 407-Connecting pipe, 408-Second connecting pipe, 500-Nozzle. Detailed Implementation

[0028] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0029] This invention discloses a mixing and feeding device for a fluidized bed unit, such as... Figure 1-9As shown, the system includes a boiler 100, a mixing and feeding mechanism 200, a discharging mechanism 300, and an air supply system 400. The boiler 100 includes a furnace body 101, with a primary air chamber 102 formed at the lower end of the furnace body 101. Air inlet nozzles 500 are installed above the primary air chamber 102, and primary air enters the furnace chamber 104 above the primary air chamber 102 through the nozzles 500. A secondary air chamber 105 is formed within the furnace chamber 104 and located above the fuel outlet of the mixing and feeding mechanism 200. The present invention has two mixing and feeding mechanisms 200 and two discharging mechanisms 300. The two mixing and feeding mechanisms 200 are located at the lower part of the boiler 100 and are positioned on two opposite sides of the boiler 100. The two discharging mechanisms 300 are respectively located at both ends of the mixing and feeding mechanisms 200, and each discharging mechanism 300 is connected to the corresponding end on the same side of the two mixing and feeding mechanisms 200. The air supply system 400 is connected to the mixing and feeding mechanism 200, the primary air chamber 102, and the secondary air chamber 105, respectively, and is used to provide primary and secondary air, promote fuel mixing, and promote uniform fuel entry into the furnace 104. The working principle and advantages of this invention are as follows: This invention supplies two fuels of different particle sizes to two feeding mechanisms 300, which simultaneously supply the two fuels to the mixing and feeding mechanism 200. During operation, the mixing and feeding mechanism 200 mixes the two fuels, and the mixed fuel enters the furnace 104 in a parabolic shape. Because the two mixing and feeding mechanisms 200 simultaneously supply the mixed fuel to the furnace 104, the two parabolic shapes formed by the fuel intersect and mix, and then gradually fall to the bottom of the furnace 104, thus preventing the fuel from falling evenly into the furnace. The bottom of the furnace 104 has problems with fuel accumulation and dead corners. The existing screw conveyor delivers fuel at a single point, and the fuel accumulation problem cannot be avoided. Therefore, the mixing and feeding mechanism 200 of the present invention, compared with the screw conveyor, can ensure that the fuel is fully burned within a predetermined time after entering the furnace 104, provided that the air supply is sufficient, thus avoiding the generation of harmful gases and tar. Moreover, the air supply system 400 not only supplies primary and secondary air, but also promotes the mixing of fuel in the mixing and feeding mechanism 200, and promotes the fuel to have a parabolic shape when entering the furnace 104.This invention can control the secondary air and the pressure gas entering the mixing and feeding mechanism 200 according to the specific combustion conditions, avoiding the loss of calorific value due to the low temperature when entering the boiler 100. In summary, this invention does not require premixing fuels of different particle sizes. It only needs to feed two fuels of different particle sizes into the mixing and feeding mechanism 200 to achieve fuel mixing. Moreover, only two mixing and feeding mechanisms 200 are needed to achieve fuel supply to the bottom of the furnace 104 of the boiler 100 without dead zones, improving the efficiency of the boiler 100, avoiding the situation of incomplete combustion causing more harmful gases and tar, and reducing equipment investment.

[0030] As a preferred embodiment of the present invention, such as Figure 5-7As shown, the mixing and feeding mechanism 200 includes an outer shell 201 and a mixing guide cylinder 207. The outer shell 201 is fixedly installed on the corresponding outer wall of the boiler 100. The outer shell 201 has a discharge port 204 that extends axially along the outer shell 201. A strip-shaped fuel inlet 106 is provided on the furnace wall of the furnace body 101. The strip-shaped fuel inlet 106 also extends axially along the outer shell 201 and extends to both ends of the outer shell 201. The discharge port 204 is connected to the strip-shaped fuel inlet 106. In this embodiment, the guide mixing tube 207 is rotatably installed inside the outer shell 201, and both ends of the guide mixing tube 207 extend out of both ends of the outer shell 201. The axis of the guide mixing tube 207 coincides with the axis of the outer shell 201. An inner feeding cavity 215 is formed inside the guide mixing tube 207, and an outer feeding mixing cavity 216 is formed between the guide mixing tube 207 and the outer shell 201. A first inlet 202 and a second inlet 203 are respectively constructed at both axial ends of the outer shell 201. The first inlet 202 communicates with the inner feeding cavity 215, and the second inlet 203 communicates with the outer feeding mixing cavity 216. Moreover, the first inlet 202 and the second inlet 203 are respectively communicated with two feeding mechanisms 300. In this embodiment, a first spiral guide blade 209 is constructed on the inner wall of the mixing orifice 207, and a second spiral guide blade 210 is constructed on the outer wall of the mixing orifice 207. The first spiral guide blade 209 and the second spiral guide blade 210 have opposite directions of rotation, and the first spiral guide blade 209 and the second spiral guide blade 210 extend spirally along the axis of the mixing orifice 207. The working principle of this embodiment is as follows: small-diameter fuel enters the inner feeding chamber 215 through the first feed port 202, and large-diameter fuel enters the outer feeding mixing chamber 216 through the second feed port 203. During the rotation of the mixing tube 207, under the action of the first spiral guide blade 209, small-diameter fuel moves from the first inlet 202 end to the second inlet 203 end of the mixing tube 207. Under the action of the second spiral guide blade 210, large-diameter fuel moves from the second inlet 203 end to the first inlet 202 end of the mixing tube 207. During the movement of the two fuels, since the diameter of the outlet hole on the mixing tube 207 is larger than the particle size of the fuel in the inner feeding chamber 215 and smaller than the particle size of the fuel in the outer feeding mixing chamber 216, the small-diameter fuel gradually enters the outer feeding mixing chamber 216 through the outlet hole on the mixing tube 207 and mixes with the large-diameter fuel. When the height of the mixed fuel in the external feeding mixing chamber 216 is not lower than the discharge port 204, the mixed fuel enters the furnace 104 in a planar form through the discharge port 204 and the strip fuel inlet 106 in sequence.Therefore, it can be seen that this embodiment does not require pre-mixing of two fuels with different particle sizes. It only needs to control the amount entering the first feed port 202 and the second feed port 203 to achieve mixing of two fuels with different ratios, and ensure that the fuel is evenly distributed at the bottom of the furnace 104, avoiding dead corners and fuel accumulation due to single-point delivery.

[0031] In a preferred embodiment of the present invention, in order to rapidly deliver the two fuels to the other end of the fuel inlet and thereby promote mixing between the fuels, the measures taken are as follows: Figure 5 , 7 As shown, the pitch of the first spiral guide blade 209 increases from the first feed port 202 to the second feed port 203, and the pitch of the second spiral guide blade 210 increases from the second feed port 203 to the first feed port 202. This increases the fuel conveying speed along the conveying direction, allowing the fuel to be quickly conveyed to the other end. Small-diameter fuel particles are continuously discharged through the discharge port into the external feeding mixing chamber 216. Furthermore, when the height of the mixed fuel in the external feeding mixing chamber 216 is not higher than the discharge port 204, the mixing of the two fuels is more thorough under the conveying and agitation of the second spiral guide blade 210. In this embodiment, the height of the discharge port 204 on the outer shell 201 is located at 1 / 3-3 / 5 of the height of the outer shell 201 in the horizontal state. Different heights of the discharge port 204 can be selected according to requirements. Generally, it is designed based on the required mixing degree of the two fuels; that is, the higher the discharge port 204, the more thoroughly the fuel is mixed.

[0032] As a preferred embodiment of the present invention, such as Figure 5 , 8As shown, a cyclone mixing pipe 211 is coaxially installed inside the mixing guide cylinder 207. The cyclone mixing pipe 211 is fixedly connected to the mixing guide cylinder 207, and one end of the cyclone mixing pipe 211 extends out of the mixing guide cylinder 207. A drive wheel 214 is installed at this end of the cyclone mixing pipe 211, and the drive wheel 214 is connected to the drive wheel on the output shaft of the drive motor via a chain drive. In this embodiment, a guide cover 213 is constructed at the other end of the cyclone mixing pipe 211. The guide cover 213 is a trumpet-shaped structure with a gradually narrowing diameter along the axis of the cyclone mixing pipe 211 toward the drive wheel 214. This trumpet-shaped structure is located at the inlet end of the inner feeding chamber 215. Multiple fine material inlets 208 are provided at the ends of the mixing orifice 207 corresponding to the material guide cover 213. These fine material inlets 208 are evenly arranged along the circumference of the mixing orifice 207. A blocking flange 206 is constructed on the inner wall of the outer shell 201 at this end. The blocking flange 206 extends radially inward along the outer shell 201 to the outer wall of the mixing orifice 207. The blocking flange 206 and the corresponding end of the outer shell 201 form a feeding chamber. All the fine material inlets 208 are located in the feeding chamber. The lower end of the feeding chamber and the bottom of the mixing orifice 207 is filled with filler to prevent small-diameter fuel particles from remaining in the lower part of the feeding chamber. In this embodiment, the guide hood 213 is located at the fine material inlet 208. Thus, small-diameter fuel enters the feeding chamber through the first feed inlet 202, and then enters the mixing guide cylinder 207 through the fine material inlet 208. During the rotation of the mixing guide cylinder 207, the guide hood 213, in conjunction with the first spiral guide blades 209, smoothly transports the small-diameter fuel, preventing fuel accumulation in the feeding chamber. To promote efficient entry of small-diameter fuel into the external feeding mixing chamber 216 and provide sufficient kinetic energy for the mixed fuel to enter the furnace 104, while ensuring the supply of secondary air, this embodiment employs a plurality of spiral air outlets 212 evenly distributed circumferentially on the cyclone mixing pipe 211. Each spiral air outlet 212 extends spirally along the axis of the cyclone mixing pipe 211, and the end of the cyclone mixing pipe 211 is connected to the air supply system 400. Pressurized air enters the cyclone mixing pipe 211 through the air supply system 400. As the cyclone mixing pipe 211 rotates, the pressurized air continuously enters the inner feeding chamber 215 in a spiral direction, agitating the small-diameter fuel particles within the inner feeding chamber 215. This allows the small-diameter fuel particles to efficiently enter the outer feeding mixing chamber 216. After entering the outer feeding mixing chamber 216, the small-diameter fuel particles mix more quickly and thoroughly with the large-diameter fuel particles under the agitation of the pressurized air and the synchronous action of the second spiral guide blades 210. Furthermore, when the mixed fuel enters the furnace 104 through the strip fuel inlet 106 on the furnace body 101, the pressurized air provides assistance, causing the mixed fuel entering the furnace 104 to form a parabolic shape, such as... Figure 4 As shown, the mixed fuels from the two mixing feed mechanisms 200 intersect, mix with each other, and are evenly distributed at the bottom of the furnace 104.

[0033] As a preferred embodiment of the present invention, such as Figure 4 , 6 As shown, a secondary air inlet 205 is provided on the outer shell 201 above the discharge port 204. The outlet end of the secondary air inlet 205 extends into the furnace 104, and the outlet end of the secondary air inlet 205 extends downward at an angle. The secondary air inlet 205 extends axially along the outer shell 201 to both ends of the outer shell 201, and the diameter of the secondary air inlet 205 gradually decreases along the air flow direction. The working principle of this embodiment is as follows: Due to the special design of the secondary air inlet 205, the secondary air enters the furnace 104 in an inclined downward planar shape. The secondary air mixes with the air entering the furnace 104 through the strip fuel inlet 106 and forms a trickle. The trickle air can supply sufficient oxygen for fuel combustion, promoting complete combustion of fuel. Furthermore, because the secondary air enters the furnace 104 in a downward-sloping planar shape, it blows upwards the unburned fuel and fly ash, ensuring that these materials come into full contact with the secondary air and achieve complete combustion. In this embodiment, the secondary air is supplied in a non-single-point manner (planar supply), thus avoiding insufficient or uneven oxygen supply.

[0034] As a preferred embodiment of the present invention, such as Figure 2 , 9 As shown, the feeding mechanism 300 includes a feeding cylinder 301 and two guide pipes 305. The lower end of the feeding cylinder 301 is trumpet-shaped, and the upper end of the feeding cylinder 301 has a connecting joint 302. The two guide pipes 305 are connected to the lower end of the feeding cylinder 301 at an angle to each other, and each guide pipe 305 is connected to the end of a corresponding mixing and feeding mechanism 200. Small-diameter or large-diameter fuel particles enter the feeding cylinder 301 through the connecting joint 302, are then evenly distributed to the two guide pipes 305, and finally supplied to the two mixing and feeding mechanisms 200. To improve the efficiency of fuel passage through the feeding cylinder 301, multiple swirling blades 304 are evenly constructed circumferentially inside the feeding cylinder 301. The fuel entering the feeding cylinder 301 swirls downward under the action of the swirling blades 304. To further improve fuel delivery efficiency and prevent clogging of the feed cylinder 301, an air inlet connector 303 is constructed at the upper part of the feed cylinder 301. This air inlet connector 303 is connected to the air supply system 400. Pressurized air enters the feed cylinder 301 through the air inlet connector 303. This air flows in a swirling pattern, driving the fuel downwards and smoothly passing through the feed cylinder 301 and the guide pipe 305 into the mixing and feeding mechanism 200.

[0035] As a preferred embodiment of the present invention, such as Figure 1-3 As shown, the air supply system 400 includes a main air inlet 401 and two branch air inlet ducts 402. The main air inlet duct 401 is connected to the two branch air inlet ducts 402, which are respectively located on two opposite sides of the boiler 100. Multiple primary air inlets 103 are constructed on the two opposite sides of the lower part of the boiler 100, and these primary air inlets 103 are all connected to the primary air chamber 102. Each branch air inlet duct 402 is connected to each primary air inlet 103 on its corresponding side and to the primary air chamber 102. In this embodiment, a first connecting pipe 404 is connected to each branch air inlet duct 402. Each first connecting pipe 404 is rotatably connected to the end of the cyclone mixing pipe 211 of the corresponding mixing and feeding mechanism 200. Furthermore, the branch air inlet duct 402 is connected to the air inlet connectors 303 of the two feeding mechanisms 300 via two second connecting pipes 408. In this embodiment, control valves are installed on each pipeline to control the airflow and opening / closing of the corresponding pipeline. Compressed air enters the two branch inlet pipes 402 through the main inlet pipe 401, and then enters the primary air chamber 102 through the primary air inlet 103. A portion of the compressed air from each branch inlet pipe 402 is diverted into the first connecting pipe 404. This portion of air enters the mixing and feeding mechanism 200 through the cyclone mixing pipe 211, promoting fuel mixing and providing kinetic energy for the mixed fuel to enter the furnace 104 in a parabolic shape. Thirdly, a portion of the air enters the secondary air chamber 105 of the furnace 104 through the secondary air inlet 205. In this embodiment, a portion of the compressed air also enters the two feed cylinders 301 through the two second connecting pipes 408, achieving efficient cyclone feeding.

[0036] As a preferred embodiment of the present invention, such as Figure 3As shown, a hot air duct 403 is provided in the primary air chamber 102. The hot air duct 403 connects to two air inlet branch pipes 402 and two hot air ducts 405. The air inlet end of a second connecting pipe 408 is connected to a hot air duct 405, and the other second connecting pipe 408 is connected to the other hot air duct 405 through a distribution pipe 406. The distribution pipe 406 is connected to the mixing and feeding mechanism 200 through two connecting pipes 407 respectively. In this embodiment, a control valve is installed on each second connecting pipe 408 and each connecting pipe 407. When it is necessary to heat the pressurized air entering the mixing and feeding mechanism 200, the discharging mechanism 300, and the secondary air chamber 105 respectively, the corresponding control valves are opened and the other control valves are closed. The pressurized air enters the two air inlet branch pipes 402 through the main air inlet pipe 401, and then enters the hot air pipe 403. Since the hot air pipe 403 is gradually heated in the primary air chamber 102, it enters the discharging mechanism 300 and the mixing and feeding mechanism 200 respectively through the hot air duct 405, thus achieving the purpose of preheating and secondary heating of the fuel. When the hot air enters the secondary air chamber 105, it avoids the situation of heat loss caused by the entry of cold air, and avoids the situation of incomplete combustion and the production of harmful gases and tar.

[0037] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A mixing and feeding device for a fluidized bed unit, characterized in that: The system includes two mixing and feeding mechanisms externally located on two opposite sides of the lower part of the boiler. Two discharging mechanisms are respectively located at both ends of the mixing and feeding mechanisms, and each discharging mechanism is connected to the same side end of the two mixing and feeding mechanisms. The air supply system is connected to the mixing and feeding mechanisms, the primary air chamber, and the secondary air chamber. The mixing and feeding mechanism includes an outer shell fixedly installed on the outer wall of the boiler. The outer shell has a discharge port extending along its axial direction, which is connected to a strip-shaped fuel inlet opened on the boiler furnace wall. A mixing guide hole is rotatably installed inside the outer shell. The cylinder has a mixing orifice shaft whose axis coincides with that of the outer cylinder shell. An inner feeding chamber is formed within the mixing orifice shaft, and an outer feeding mixing chamber is formed between the mixing orifice shaft and the outer cylinder shell. A first inlet and a second inlet are respectively constructed at both axial ends of the outer cylinder shell. The first inlet communicates with the inner feeding chamber, and the second inlet communicates with the outer feeding mixing chamber. Both the first and second inlets are also connected to two feeding mechanisms. A first spiral guide blade and a second spiral guide blade with opposite rotation directions are respectively constructed on the inner and outer walls of the mixing orifice shaft. Furthermore, the first and second spiral guide blades extend spirally along the axis of the mixing orifice cylinder; the pitch of the first spiral guide blade increases from the first inlet to the second inlet, and the pitch of the second spiral guide blade increases from the second inlet to the first inlet. The diameter of the outlet hole on the mixing orifice cylinder is larger than the particle size of the fuel in the inner feeding chamber, and the diameter of the outlet hole is smaller than the particle size of the fuel in the outer feeding mixing chamber. The height of the outlet on the outer cylinder shell is located at 1 / 3-3 / 5 of the outer cylinder shell in the horizontal state. A cyclone mixing pipe is coaxially mounted, with one end extending out of the mixing guide tube. A drive wheel is installed at this end of the cyclone mixing pipe, and a guide cover is constructed at the other end of the cyclone mixing pipe. The guide cover is a funnel-shaped structure with a gradually narrowing diameter along the axis of the cyclone mixing pipe toward the drive wheel. This funnel-shaped structure is located at the inlet end of the inner feeding chamber. Multiple spiral air outlets are evenly opened along the circumference of the cyclone mixing pipe, and each spiral air outlet extends spirally along the axis of the cyclone mixing pipe. The end of the cyclone mixing pipe is connected to the air supply system.

2. A mixing and feeding device for a fluidized bed unit according to claim 1, characterized in that A secondary air inlet is provided on the outer shell and above the discharge port, extending into the furnace. The secondary air inlet extends along the axial direction of the outer shell to both ends of the outer shell, and the diameter of the secondary air inlet gradually decreases along the direction of air flow.

3. The mixing and feeding device for a fluidized bed unit according to claim 1, characterized in that: The feeding mechanism includes a feeding cylinder with a connecting joint at the upper end, and two guide pipes connected to the lower end of the feeding cylinder. Each guide pipe is connected to the end of a corresponding mixing and feeding mechanism. Multiple rotating blades are uniformly arranged along the circumference inside the feeding cylinder, and an air inlet joint is arranged at the upper part of the feeding cylinder. The air inlet joint is connected to an air supply system.

4. The mixing and feeding device of a fluidized bed unit according to claim 1, characterized in that: The air supply system includes two air inlet branch pipes connected to the main air inlet pipe. The two air inlet branch pipes are respectively located on two opposite sides of the boiler. Each air inlet branch pipe is connected to the primary air chamber through the primary air inlet at the bottom of the boiler. Each air inlet branch pipe is connected to a first connecting pipe. Each first connecting pipe is connected to the corresponding mixing and feeding mechanism. The air inlet branch pipe is also connected to two feeding mechanisms through two second connecting pipes.

5. A mixing and charging device for a fluidized bed apparatus according to claim 4, characterized in that: A hot air duct is provided in the primary air chamber. The hot air duct is connected to two air inlet branch pipes. The air inlet end of one second connecting pipe is connected to the hot air duct. The other second connecting pipe is connected to the hot air duct through a distribution pipe. The distribution pipe is connected to the mixing and feeding mechanism through two connecting pipes respectively.

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