A low nitrogen oxide emission oxygen-enriched pulverized coal recirculation premix burner

Abstract

The invention discloses an oxygen-enriched pulverized coal reflux premixing burner with low nitrogen oxide emission, comprising a first air duct, a perimeter air duct, a connector, a second air duct, an oil gun, a first oxygen pipe, a second oxygen pipe, a first aeration and filtering mechanism, a second aeration and filtering mechanism, a first spiral speed increasing mechanism and a second spiral speed increasing mechanism. The invention provides the first aeration and filtering mechanism and the second aeration and filtering mechanism at the upper ends of the first air duct and the second air duct, and the pulverized coal is transported through a discharge pipe, and then the pulverized coal passes through the air holes at the upper end of a driven gear for uniform dispersion, and at the same time, a motor drives a driving gear to rotate through a rotating shaft, so that the driving gear drives a driven gear, so that the pulverized coal is uniformly dispersed and transported, and then the pulverized coal is transported in a spiral shape through a spiral protrusion, so that the pulverized coal can be fully mixed with oxygen, thereby achieving the advantages of being able to fully mix the pulverized coal with oxygen and reducing the generation of nitrogen oxides.

Description

Technical Field

[0001] The present invention specifically relates to an oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emission, and relates to the relevant field of coal-fired burners. Background Art

[0002] A burner is a general term for a device that sprays fuel and air in a certain way for mixed combustion. Burners are divided into industrial burners, burners, civil burners, and special burners according to their types and application areas. They are mostly made of corrosion-resistant and high-temperature resistant materials such as stainless steel or titanium.

[0003] When the oxygen-enriched pulverized coal reflux premixed burner is used, flue gas containing a large amount of nitrogen oxides will inevitably be produced. After the flue gas is discharged, it is easy to pollute the environment, thus affecting human health and being detrimental to social progress and development. Summary of the invention

[0004] Therefore, in order to solve the above-mentioned deficiencies, the present invention provides an oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emissions.

[0005] The present invention is implemented in this way: a low nitrogen oxide emission oxygen-enriched pulverized coal reflux premix burner is constructed, the device includes a first air duct, a perimeter air duct, a connector, a second air duct, an oil gun, a first oxygen pipe, a second oxygen pipe, a first aeration filter mechanism, a second aeration filter mechanism, a first spiral speed-increasing mechanism and a second spiral speed-increasing mechanism, the first air duct is connected to the top of the perimeter air duct, the first aeration filter mechanism is installed at the bottom of the connector, the second aeration filter mechanism is fixed to the bottom of the second air duct, the first oxygen pipe and the second oxygen pipe are respectively provided with a first spiral speed-increasing mechanism and a second spiral speed-increasing mechanism at the bottom, the first The aeration and filtering mechanism and the second aeration and filtering mechanism have the same structure. The first aeration and filtering mechanism and the second aeration and filtering mechanism have the same structure. The first aeration and filtering mechanism includes a mounting frame, a motor, a rotating shaft, a driving gear, a driven gear, a guide mechanism, a discharge pipe and a spiral protrusion. The discharge pipe is connected to the bottom of the connector. The discharge pipe is fixedly connected to the left end of the mounting frame. The mounting frame is bolted to the upper end of the motor. The motor is rotatably connected to the middle part of the driving gear through the rotating shaft. The driving gear is engaged with the right end of the driven gear. The driven gear is movably connected to the inner side of the guide mechanism. A spiral protrusion is arranged inside the discharge pipe.

[0006] Preferably, the first air duct is connected to the top of the connector, a second air duct is arranged at the front end of the first air duct, an oil gun is embedded in the inner side of the second air duct, and a first oxygen tube and a second oxygen tube are arranged oppositely at the front and rear ends of the bottom of the oil gun.

[0007] Preferably, the guide mechanism includes a vertical plate, a first connecting block, a groove, a compression spring, a fixed plate, a movable bead, a sliding column and a second connecting block. The left end of the vertical plate is fixed to the inner side of the discharge pipe, and the second connecting block and the first connecting block are relatively arranged on the upper and lower sides of the vertical plate. A groove is opened at the upper end of the first connecting block, and the sliding column slides with the inner side of the groove. The sliding column is fixedly connected to the bottom of the fixed plate, and the fixed plate is elastically connected to the inner side of the groove through a compression spring, and a movable bead is movably nested on the top of the fixed plate.

[0008] Preferably, the first spiral speed increasing mechanism and the second spiral speed increasing mechanism have the same structure, and the first spiral speed increasing mechanism comprises a fixed sleeve, an air inlet, a guide slope, a swirl groove, a rotating rod and a propeller blade. The fixed sleeve is communicated with the bottom of the first oxygen pipe, an air inlet is opened in the middle of the fixed sleeve, a guide slope is arranged on the inner wall of the air inlet, swirl grooves are equidistantly distributed on the upper end of the guide slope, a rotating rod is arranged in the middle of the air inlet, and the rotating rod is rotatably connected to the middle of the propeller blade.

[0009] Preferably, a cross bar is provided in the middle of the fixing sleeve, and the rotating rod is rotatably connected to the middle of the cross bar.

[0010] Preferably, the propeller blades are distributed in an oblique manner from front to back, and the number of the propeller blades is greater than two, and they are distributed equidistantly along the upper end of the rotating rod.

[0011] Preferably, the air inlet on the inner side of the fixing sleeve has a constricted contour structure, and the throat portion of the air inlet has a sloped structure.

[0012] Preferably, the first connecting block and the second connecting block have the same size, and grooves, compression springs, fixed plates, movable beads and sliding columns are provided inside the first connecting block and the second connecting block.

[0013] Preferably, the vertical plate, the first connecting block and the second connecting block mutually form a U shape, and the driven gear is embedded in the inner side of the middle opening of the first connecting block and the second connecting block and contacts with the upper end of the movable bead.

[0014] Preferably, the upper end of the driven gear is provided with air holes, and the number of the air holes is greater than two.

[0015] Preferably, the adsorption layer is made of modified activated carbon powder, which is beneficial for removing nitrogen dioxide, sulfur oxides, etc.

[0016] Preferably, the rotating shaft is made of carbon steel with high hardness.

[0017] The present invention has the following advantages: The present invention provides an oxygen-enriched coal powder reflux premix burner with low nitrogen oxide emission through improvement, which has the following improvements compared with similar equipment:

[0018] Advantage 1: The oxygen-enriched pulverized coal reflux premixing burner with low nitrogen oxide emissions described in the present invention has a first aeration and filtering mechanism and a second aeration and filtering mechanism arranged at the upper ends of the first air duct and the second air duct. The pulverized coal is transported through the emission pipe, and then the pulverized coal is evenly dispersed through the air holes at the upper end of the driven gear. At the same time, the motor drives the driving gear to rotate through the rotating shaft, so that the driving gear drives the driven gear to evenly disperse and transport the pulverized coal. Then, the pulverized coal is transported in a spiral shape through the spiral protrusion, so that the pulverized coal can be fully mixed with oxygen, thereby achieving the advantages of fully mixing the pulverized coal with oxygen and reducing the generation of nitrogen oxides.

[0019] Advantage 2: The oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emissions described in the present invention has a guide mechanism set at the upper end of the aeration and filtration mechanism. When the driven gear rotates, the driven gear will contact the movable beads at the upper ends of the first connecting block and the second connecting block to guide the driven gear. At the same time, the fixed plate will press the compression spring to cause deformation, thereby absorbing the polarization force at the upper end of the driven gear, thereby achieving the advantage of enabling the driven gear to rotate smoothly.

[0020] Advantage 3: The oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emissions described in the present invention has a first spiral speed-increasing mechanism and a second spiral speed-increasing mechanism arranged on the upper ends of the first oxygen pipe and the second oxygen pipe. Oxygen is discharged through the air inlet, and the oxygen can be guided by the guide slope and the swirl groove. At the same time, the oxygen will drive the propeller blades to rotate, so that the oxygen is transported in a spiral shape, the oxygen contact area is expanded, and the oxygen transport rate is increased at the same time, achieving the advantages of being able to spirally transport oxygen and increase the mixing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the cross-sectional structure of the burner of the present invention;

[0023] Figure 3 It is a schematic diagram of the cross-sectional structure of the aeration and filtration mechanism of the present invention;

[0024] Figure 4 It is a schematic diagram of the cross-sectional structure of the driving gear of the present invention;

[0025] Figure 5 It is a schematic diagram of the three-dimensional structure of the guide mechanism of the present invention;

[0026] Figure 6 It is a schematic diagram of the three-dimensional structure of the spiral speed increasing mechanism of the present invention.

[0027] Wherein: first air duct-1, perimeter air duct-2, connector-3, first aeration and filtering mechanism-4, second air duct-5, second aeration and filtering mechanism-6, oil gun-7, first oxygen tube-8, first spiral speed increasing mechanism-9, second oxygen tube-10, second spiral speed increasing mechanism-11, installation frame-41, motor-42, rotating shaft-43, driving gear-44, driven gear-45, guide mechanism-46, discharge pipe-47, spiral protrusion-48, vertical plate-461, first connection Block -462, groove -463, compression spring -464, fixed plate -465, movable bead -466, sliding column -467, second connecting block -468, vertical plate -461, first connecting block -462, groove -463, compression spring -464, fixed plate -465, movable bead -466, sliding column -467, second connecting block -468, fixing sleeve -91, air inlet -92, guide slope -93, swirl groove -94, rotating rod -95, propeller blade -96, air vent -451. DETAILED DESCRIPTION

[0028] The following will be combined with the attached Figure 1-6 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] See also Figure 1-2 The present invention provides an oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emission through improvement, comprising a first air duct 1, a perimeter air duct 2, a connector 3, a second air duct 5, an oil gun 7, a first oxygen tube 8, a second oxygen tube 10, a first aeration and filtering mechanism 4, a second aeration and filtering mechanism 6, a first spiral speed-increasing mechanism 9 and a second spiral speed-increasing mechanism 11, the first air duct 1 is connected to the top of the perimeter air duct 2, the first aeration and filtering mechanism 4 is installed at the bottom of the connector 3, the second aeration and filtering mechanism 6 is fixed to the bottom of the second air duct 5, the first oxygen tube 8 and the second oxygen tube 10 are respectively provided with the first spiral speed-increasing mechanism 9 and the second spiral speed-increasing mechanism 11 at the bottom, the first aeration and filtering mechanism 4 and the second aeration and filtering mechanism 6 have the same structure, the first air duct 1 is connected to the top of the connector 3, the second air duct 5 is provided at the front end of the first air duct 1, the oil gun 7 is embedded and installed inside the second air duct 5, and the first oxygen tube 8 and the second oxygen tube 10 are relatively provided at the front and rear ends of the bottom of the oil gun 7.

[0031] See also Figure 3-4The present invention provides an oxygen-enriched coal powder reflux premix burner with low nitrogen oxide emission through improvement. The first aeration and filtering mechanism 4 and the second aeration and filtering mechanism 6 have the same structure. The first aeration and filtering mechanism 4 includes a mounting frame 41, a motor 42, a rotating shaft 43, a driving gear 44, a driven gear 45, a guide mechanism 46, a discharge pipe 47 and a spiral protrusion 48. The discharge pipe 47 is connected to the bottom of the connector 3, and the discharge pipe 47 is fixedly connected to the left end of the mounting frame 41. The mounting frame 41 is bolted to the upper end of the motor 42. The motor 42 is rotatably connected to the middle part of the driving gear 44 through the rotating shaft 43. The driving gear 44 is engaged with the right end of the driven gear 45. The driven gear 45 is movably connected to the inner side of the guide mechanism 46. A spiral protrusion 48 is arranged inside the discharge pipe 47. An air hole 451 is arranged at the upper end of the driven gear 45, and the number of the air holes 451 is greater than two. The adsorption layer 49 is made of modified activated carbon powder, which is beneficial to the removal of nitrogen dioxide, sulfur oxides, etc. The rotating shaft 43 is made of carbon steel with high hardness.

[0032] See also Figure 5 The present invention provides an oxygen-enriched pulverized coal reflux premixed burner with low nitrogen oxide emission through improvement. The guide mechanism 46 includes a vertical plate 461, a first connecting block 462, a groove 463, a compression spring 464, a fixed disk 465, a movable bead 466, a slide column 467 and a second connecting block 468. The left end of the vertical plate 461 is fixed to the inner side of the discharge pipe 47. The second connecting block 468 and the first connecting block 462 are arranged on the upper and lower sides of the vertical plate 461. The upper end of the first connecting block 462 is provided with a groove 463. The slide column 467 is slidably matched with the inner side of the groove 463. The slide column 467 is fixedly connected to the bottom of the fixed disk 465. The fixed disk 465 is connected to the bottom of the fixed disk 465 by the compression spring 464. 64 is elastically connected to the inner side of the groove 463, a movable bead 466 is movably embedded on the top of the fixed plate 465, the first connecting block 462 and the second connecting block 468 are of the same size, and the first connecting block 462 and the second connecting block 468 are both provided with a groove 463, a compression spring 464, a fixed plate 465, a movable bead 466, and a sliding column 467, the vertical plate 461, the first connecting block 462 and the second connecting block 468 form a U-shape with each other, and the driven gear 45 is embedded in the inner side of the middle opening of the first connecting block 462 and the second connecting block 468, and contacts with the upper end of the movable bead 466, which is conducive to the smooth rotation of the driven gear 45.

[0033] See also Figure 6The present invention provides an oxygen-enriched coal powder reflux premixed burner with low nitrogen oxide emission through improvement. The first spiral speed-increasing mechanism 9 and the second spiral speed-increasing mechanism 11 have the same structure. The first spiral speed-increasing mechanism 9 includes a fixed sleeve 91, an air inlet 92, a guide slope 93, a swirl groove 94, a rotating rod 95 and a propeller blade 96. The fixed sleeve 91 is connected to the bottom of the first oxygen pipe 8. The middle part of the fixed sleeve 91 is provided with an air inlet 92. The inner wall of the air inlet 92 is provided with a guide slope 93. The upper end of the guide slope 93 is evenly distributed with swirl grooves. 94, a rotating rod 95 is provided in the middle of the air inlet 92, and the rotating rod 95 is rotatably connected to the middle of the propeller blade 96, a cross bar 97 is provided in the middle of the fixed sleeve 91, and the rotating rod 95 is rotatably connected to the middle of the cross bar 97, the propeller blades 96 are distributed in an oblique shape from front to back, and the number of the propeller blades 96 is greater than two, and they are equidistantly distributed along the upper end of the rotating rod 95, the air inlet 92 inside the fixed sleeve 91 is a contracted contour structure, and the throat part of the air inlet 92 is a sloped structure, which is conducive to the role of spirally transporting oxygen.

[0034] Embodiment 2:

[0035] The present invention provides an oxygen-enriched coal powder reflux premixed burner with low nitrogen oxide emissions through improvements. The driving gear 44 and the driven gear 45 have the same thickness, and the driving gear 44 and the driven gear 45 are distributed parallel to each other, which is conducive to driving the driven gear 45 to be linked. The number of movable beads 466 is greater than two, and the surfaces of the movable beads 466 are smooth, which is conducive to guiding the driven gear 45.

[0036] The present invention provides an oxygen-enriched coal powder reflux premix burner with low nitrogen oxide emission through improvement, and its working principle is as follows;

[0037] First, install the oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emission at a suitable position on the upper end of the boiler before use;

[0038] Second, when in use, the corresponding delivery pipelines are connected to the upper ends of the discharge pipe 47 and the fixing sleeve 91 respectively;

[0039] Third, the coal powder is then transported through the discharge pipe 47, and then the coal powder passes through the air hole 451 at the upper end of the driven gear 45 to be evenly dispersed. At the same time, the motor 42 drives the driving gear 44 to rotate through the rotating shaft 43, so that the driving gear 44 drives the driven gear 45, so that the coal powder is evenly dispersed and transported, and then the coal powder is transported in a spiral shape through the spiral protrusion 48, so that the coal powder can be fully mixed with oxygen;

[0040] Fourth, oxygen is discharged through the air inlet 92, and the oxygen can be guided by the guide slope 93 and the swirl groove 94. At the same time, the oxygen drives the propeller blades 96 to rotate, so that the oxygen is transported in a spiral shape, and the oxygen transport rate is increased, so that the oxygen and the coal powder are fully mixed;

[0041] Fifth, the oxygen and the pulverized coal are then fully mixed, and a part of the pulverized coal flows out from the first air duct 1, and the other part flows back and mixes into the second air duct 5. After the primary air pulverized coal is sprayed out from the first air duct 1, it is immediately slowed down by the reflux cap inside the oil gun 7, and is driven by the slow wind of the second air duct 5 to continue to be transported. After flowing through the front end of the reflux cap inside the oil gun 7, it flows back again to be premixed with the pulverized coal in the first air duct 1 at the outlet of the air-powder channel, and then the local premixing is ignited;

[0042] Sixth, since oxygen and pulverized coal are fully mixed, the pulverized coal can be fully burned, reducing the generation of nitrogen oxides.

[0043] The present invention provides an oxygen-enriched pulverized coal reflux premixing burner with low nitrogen oxide emission through improvement. The first aeration and filtering mechanism 4 and the second aeration and filtering mechanism 6 are arranged at the upper ends of the first air duct 1 and the second air duct 5. The pulverized coal is transported through the discharge pipe 47, and then the pulverized coal passes through the air vent 451 at the upper end of the driven gear 45 to be evenly dispersed. At the same time, the motor 42 drives the driving gear 44 to rotate through the rotating shaft 43, so that the driving gear 44 drives the driven gear 45 to evenly disperse and transport the pulverized coal. Then, the pulverized coal is transported in a spiral shape through the spiral protrusion 48, so that the pulverized coal can be fully mixed with oxygen, thereby achieving the advantages of being able to fully mix the pulverized coal with oxygen and reducing the generation of nitrogen oxides. By arranging a guide mechanism 46 at the upper end of the aeration and filtering mechanism, when the driven gear 45 rotates, The driven gear 45 contacts the movable bead 466 at the upper ends of the first connecting block 462 and the second connecting block 468 to guide the driven gear 45. At the same time, the fixed plate 465 presses the compression spring 464 to cause deformation, and absorbs the polarization force at the upper end of the driven gear 45, thereby achieving the advantage of enabling the driven gear 45 to rotate smoothly. By arranging the first spiral speed increasing mechanism 9 and the second spiral speed increasing mechanism 11 at the upper ends of the first oxygen tube 8 and the second oxygen tube 10, oxygen is discharged through the air inlet 92, and the oxygen can be guided by the guide slope 93 and the swirl groove 94. At the same time, the oxygen will drive the propeller blades 96 to rotate, so that the oxygen is transported in a spiral shape, the contact area of ​​the oxygen is expanded, and the oxygen transport rate is increased, thereby achieving the advantages of being able to spirally transport the oxygen and increase the mixing efficiency.

[0044] The above shows and describes the basic principle, main features and advantages of the present invention, and the standard parts used in the present invention can be purchased from the market, and special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part adopt the conventional means such as mature bolts, rivets, welding, etc. in the prior art. The machinery, parts and equipment all adopt the conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be described in detail here.

[0045] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An oxygen-enriched pulverized coal reflux premix burner with low nitrogen oxide emission, comprising a first air duct (1), a peripheral air duct (2), a connector (3), a second air duct (5), an oil gun (7), a first oxygen pipe (8) and a second oxygen pipe (10), wherein the first air duct (1) is connected to the top of the peripheral air duct (2); Features: The invention also comprises a first aeration and filtering mechanism (4), a second aeration and filtering mechanism (6), a first spiral speed-increasing mechanism (9) and a second spiral speed-increasing mechanism (11); the first aeration and filtering mechanism (4) is mounted on the bottom of the connector (3); the second aeration and filtering mechanism (6) is fixed to the bottom of the second air duct (5); the first oxygen pipe (8) and the second oxygen pipe (10) are respectively provided with the first spiral speed-increasing mechanism (9) and the second spiral speed-increasing mechanism (11); the first aeration and filtering mechanism (4) and the second aeration and filtering mechanism (6) have the same structure; the first aeration and filtering mechanism (4) comprises a mounting frame (41); ), a motor (42), a rotating shaft (43), a driving gear (44), a driven gear (45), a guide mechanism (46), a discharge pipe (47) and a spiral protrusion (48), wherein the discharge pipe (47) is connected to the bottom of the connector (3), the discharge pipe (47) is fixedly connected to the left end of the mounting frame (41), the mounting frame (41) is bolted to the upper end of the motor (42), the motor (42) is rotatably connected to the middle part of the driving gear (44) through the rotating shaft (43), the driving gear (44) is meshed with the right end of the driven gear (45), the driven gear (45) is connected to the inner part of the guide mechanism (46), and the inner part of the driving gear (44) is engaged with the right end of the driven gear (45). The first air duct (1) is movably connected to the side, and a spiral protrusion (48) is arranged inside the discharge pipe (47); the first air duct (1) is connected to the top of the connector (3); a second air duct (5) is arranged at the front end of the first air duct (1), and an oil gun (7) is embedded and installed inside the second air duct (5); the first oxygen tube (8) and the second oxygen tube (10) are arranged at the front and rear ends of the bottom of the oil gun (7) in a relative manner; the guide mechanism (46) comprises a vertical plate (461), a first connecting block (462), a groove (463), a compression spring (464), a fixing plate (465), a movable bead (466), a sliding column (467) and a second A connecting block (468), the left end of the vertical plate (461) is fixed to the inner side of the discharge pipe (47), the second connecting block (468) and the first connecting block (462) are arranged oppositely on the upper and lower sides of the vertical plate (461), the upper end of the first connecting block (462) is provided with a groove (463), the sliding column (467) is slidably matched with the inner side of the groove (463), the sliding column (467) is fixedly connected to the bottom of the fixed plate (465), the fixed plate (465) is elastically connected to the inner side of the groove (463) through a compression spring (464), and a movable bead (466) is movably embedded on the top of the fixed plate (465);The first spiral speed increasing mechanism (9) and the second spiral speed increasing mechanism (11) have the same structure. The first spiral speed increasing mechanism (9) comprises a fixed sleeve (91), an air inlet (92), a flow guide slope (93), a swirl groove (94), a rotating rod (95) and a propeller blade (96). The fixed sleeve (91) is connected to the bottom of the first oxygen pipe (8). The fixed sleeve (91) is provided with an air inlet (92) in the middle. The inner wall of the air inlet (92) is provided with a A guide slope (93) is provided, and swirl grooves (94) are evenly distributed on the upper end of the guide slope (93); a rotating rod (95) is provided in the middle of the air inlet (92), and the rotating rod (95) is rotatably connected to the middle of the propeller blade (96); a cross bar (97) is provided in the middle of the fixed sleeve (91), and the rotating rod (95) is rotatably connected to the middle of the cross bar (97); the propeller blade (96) is distributed in an oblique shape from front to back, and the propeller blade (96) The number of the plurality of connecting blocks (461) is greater than two and is equidistantly distributed along the upper end of the rotating rod (95); the air inlet (92) inside the fixed sleeve (91) is a constricted profile structure, and the throat portion of the air inlet (92) is a sloped structure; the first connecting block (462) and the second connecting block (468) are of the same size, and the first connecting block (462) and the second connecting block (468) are both provided with a groove (463), a compression spring (464), a fixed plate (465), a movable bead (466), and a sliding column (467); the vertical plate (461), the first connecting block (462), and the second connecting block (468) mutually form a U-shape, and the driven gear (45) is embedded in the inner side of the middle opening of the first connecting block (462) and the second connecting block (468), and contacts the upper end of the movable bead (466); the upper end of the driven gear (45) is provided with an air vent (451), and the number of the air vent (451) is greater than two. ;

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