Water-cooled premix combustion device

Abstract

The application relates to a water-cooled premix combustion device, which comprises a mixer, an air blower, an air chamber, a uniform air hole plate, a fire-resistant tube, a flame-stabilizing tube, upper and lower water chambers and a base, the air outlet of the air blower is fixedly connected with the air inlet of the mixer, and the air chamber is fixedly connected with the air outlet end of the mixer. The application has the beneficial effects that: through heat exchange between the flame and the cooling water in the fire-resistant tube and the flame-stabilizing tube, a large amount of cooling water can efficiently take away heat, the flame temperature is more effectively reduced, the generation of harmful gases such as NOx is reduced, the flame combustion is stable, the length of the flame is short, and the phenomena such as backfire explosion, blockage and flameout do not occur, since the flame of the premix combustion is short, the depth of the furnace can be reduced, the volume of the boiler can be reduced, and materials can be saved, meanwhile, through the multistage damping system, residual vibration is inhibited from being transmitted to the external structure, the device is suitable for high and low load working conditions, especially in the resonance frequency band, the device can still keep stable operation, and the long-term reliability of the boiler is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, and more specifically to a water-cooled premixed combustion device. Background Technology

[0002] Water-cooled premixed boilers mix fuel gas and air in a suitable ratio before introducing the mixture into a specially designed burner cooled by boiler water. Because of the boiler water cooling, the flame temperature can be effectively controlled, suppressing the formation of thermal nitrogen oxides. Furthermore, the premixed combustion promotes complete fuel combustion, thus achieving low-pollution and high-efficiency combustion.

[0003] In existing technologies, water-cooled premixed boiler grates typically use small-diameter tube structures. The heat exchange area of ​​small-diameter tubes is limited, resulting in low cooling efficiency and difficulty in quickly balancing flame temperature fluctuations, which affects combustion efficiency. When the boiler operating load decreases, the flow rate of the mixed gas decreases, and the airflow frequency may approach the natural frequency of the pipe, causing mechanical resonance and leading to increased pipe vibration. Long-term operation will accelerate material fatigue or even breakage. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a water-cooled premixed combustion device with a simple and stable structure, which further reduces the flame combustion temperature, suppresses the generation of nitrogen oxides, and is less prone to resonance.

[0005] This invention provides the following technical solution: a water-cooled premixed combustion device, comprising: mixer; The blower's outlet is fixedly connected to the mixer's inlet; The air chamber is fixedly connected to the air outlet of the mixer; A gas distribution plate is fixedly connected inside the gas chamber near the mixer. Flame arrestor tubes are fixedly connected to the inside of the gas chamber and located on the side of the gas equalization plate away from the mixer. Several flame arrestor tubes are arranged in parallel at equal intervals along the vertical direction inside the gas chamber. Flame stabilizers are fixedly connected to the inside of the gas chamber and located on the side of the flame arrestor tube away from the gas equalization plate. Several flame stabilizers are arranged in parallel at equal intervals along the vertical direction inside the gas chamber. The upper and lower water chambers are located at the top and bottom of the gas chamber, and the flame arrestor pipe and flame stabilizer pipe are connected to the upper and lower water chambers.

[0006] As a preferred embodiment of the present invention, a first gap is formed between two connected flame arrestor tubes, and a second gap is formed between two adjacent flame stabilizer tubes.

[0007] As a preferred embodiment of the present invention, the three first gaps formed between four adjacent flame arrestor tubes correspond to the two second gaps formed between three adjacent flame stabilizer tubes.

[0008] As a preferred embodiment of the present invention, the two first gaps formed between three adjacent flame arrestor tubes correspond to a second gap formed between two adjacent flame stabilizer tubes.

[0009] As a preferred embodiment of the present invention, the flame arrestor tube adopts a square core tube structure.

[0010] As a preferred embodiment of the present invention, the flame arrestor tube adopts a square core tube structure.

[0011] As a preferred embodiment of the present invention, the flame stabilizer tube adopts a circular core tube structure, and the diameter of the flame stabilizer tube is greater than the length and width of the flame arrestor tube.

[0012] As a preferred embodiment of the present invention, a mounting frame is fixedly connected to the outside of the blower, and mounting feet are fixedly connected to the left and right ends of the bottom of the upper and lower water chambers. The bottom of the mounting frame and the mounting feet are fixedly connected to the base by multiple sets of bolts. A drive motor is fixedly installed at the front end of the top of the base, and the drive end of the drive motor is connected to the rotating shaft of the blower through a pulley set.

[0013] As a preferred embodiment of the present invention, connecting columns are fixedly connected to the four corners of the bottom of the base, and the bottom ends of multiple sets of connecting columns are slidably connected to the vibration damping box. A lifting plate is fixedly connected inside the vibration damping box and at the bottom of the connecting columns. Connecting heads are fixedly connected to the four corners of the bottom of the lifting plate. Linkage rods are hinged to the bottom ends of multiple sets of connecting heads. Sliding sleeves are hinged to the bottom ends of multiple sets of linkage rods. Sliding sleeves are slidably connected to the bottom of the vibration damping box through sliding rods. Buffer springs are sleeved on the outer sides of multiple sets of sliding rods. Multiple sets of dampers are fixedly installed between the bottom of the lifting plate and the vibration damping box.

[0014] As a preferred embodiment of the present invention, rubber sealing rings are fixedly connected to the connection points between the inside of the vibration damping box and the multiple sets of connecting columns, and stabilizing plates are fixedly connected to both ends of the bottom of the lifting plate. Stabilizing wheels are rotatably connected to both ends of the stabilizing plates, and the stabilizing wheels are in contact with the inner sidewall of the vibration damping box.

[0015] The beneficial effects of this invention are: In this invention, external air is fed into the mixer by a blower and fully premixed with the fuel gas. The mixed gas then enters the gas chamber and is ignited after being evenly distributed by a gas distribution plate. The flame passes through a flame arrestor and a flame stabilizer, and heat is exchanged between the flame and the cooling water in the flame arrestor and flame stabilizer. A large amount of cooling water can efficiently remove heat and more effectively reduce the flame temperature, thereby reducing the generation of harmful gases such as NOx. Furthermore, the flame combustion is stable and short, and there will be no backfire, deflagration, blockage, or flameout. Because the premixed combustion flame is short, the depth of the furnace can be reduced, thereby reducing the boiler volume and saving materials. In this invention, through the cooperative design of the base and the vibration damping box, when the base vibrates due to the operation of the combustion device, the vibration is transmitted to the inside of the vibration damping box through the connecting columns at the four corners. The bottom of the connecting column pushes the lifting plate downward, causing the connecting head and the hinged linkage rod to move. The linkage rod drives the sliding sleeve to slide along the sliding rod, compressing the buffer spring to absorb the impact energy. Multiple sets of dampers work together to suppress the reciprocating motion amplitude of the lifting plate, achieving vibration attenuation. After the vibration weakens, the buffer spring releases elastic potential energy, pushing the sliding sleeve back to its original position. The linkage rod drives the lifting plate to return to its initial position. When the connecting column vibrates with the base, the rubber sealing ring deforms elastically. It absorbs high-frequency vibrations while preventing dust or liquid from entering the vibration damping box. It isolates vibrations and protects the internal structure of the vibration damping box from contamination or corrosion, extending its service life. When the lifting plate is pressed down by vibration, the stabilizing plate drives the stabilizing wheel to roll along the inner wall of the vibration damping box, limiting the lateral displacement of the lifting plate. The rolling friction of the stabilizing wheel replaces the sliding friction, reducing motion resistance and ensuring the stability of the vertical movement trajectory of the lifting plate. In conjunction with the buffer spring and damper, it forms a multi-stage vibration damping system, further suppressing the transmission of residual vibration to the external structure. It is suitable for high and low load conditions, and can maintain stable operation, especially in the resonant frequency band, ensuring the long-term reliability of the boiler. Attached Figure Description

[0016] Figure 1 A schematic diagram of the overall structure of a large-diameter water-cooled premixed combustion device; Figure 2 This is a schematic diagram of the cross-sectional structure of the gas chamber, flame arrestor tube, and flame stabilizer tube. Figure 3 This is a schematic diagram of a first example structure of a flame arrestor tube and a flame stabilizer tube; Figure 4 This is a schematic diagram of a second example structure for a flame arrestor tube and a flame stabilizer tube. Figure 5 This is a schematic diagram of a third example structure for a flame arrestor tube and a flame stabilizer tube; Figure 6 This is a schematic diagram of the internal structure of the vibration damping box; Figure 7 for Figure 6 Enlarged view of point A in the middle; In the diagram: 1. Blower; 2. Mixer; 3. Air chamber; 4. Air distribution plate; 5. Upper and lower water chambers; 6. Flame arrestor pipe; 7. Flame stabilizer pipe; 8. Base; 801. Mounting frame; 802. Mounting feet; 803. Drive motor; 804. Pulley assembly; 9. Vibration damping box; 901. Connecting column; 902. Lifting plate; 903. Connector; 904. Linkage rod; 905. Sliding sleeve; 906. Sliding rod; 907. Buffer spring; 908. Damper; 909. Rubber sealing ring; 910. Stabilizing plate; 911. Stabilizing wheel. Detailed Implementation

[0017] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example like Figures 1 to 7 As shown, a water-cooled premixed combustion device includes a mixer 2, a blower 1, a gas chamber 3, a gas equalization plate 4, a flame arrestor 6, a flame stabilizer 7, and upper and lower water chambers 5.

[0019] The mixer 2 is equipped with an air outlet, an air outlet end, and an air inlet end. The air inlet end is connected to the gas supply pipeline. The air outlet of the blower 1 is fixedly connected to the air inlet of the mixer 2. The gas chamber 3 is fixedly connected to the air outlet end of the mixer 2. The gas equalization plate 4 is fixedly connected inside the gas chamber 3 near the mixer 2. The flame arrestor pipe 6 is fixedly connected inside the gas chamber 3 and located on the side of the gas equalization plate 4 away from the mixer 2. The flame arrestor pipes 6 are arranged side by side at equal intervals in the vertical direction inside the gas chamber 3. Several flame stabilizers 7 are fixedly connected inside the gas chamber 3 and located on the side of the flame arrestor 6 away from the gas equalization plate 4. Several flame stabilizers 7 are arranged in parallel at equal intervals along the vertical direction inside the gas chamber 3. The upper and lower water chambers 5 are located at the top and bottom of the gas chamber 3. The flame arrestor 6 and the flame stabilizers 7 are connected to the upper and lower water chambers 5. One of the upper and lower water chambers 5 is the water inlet chamber and the other is the water outlet chamber. Cold water is drawn through the water inlet chamber and the water outlet chamber and circulates in the flame arrestor 6 and the flame stabilizers 7.

[0020] During operation, external air is fed into the mixer 2 by the blower 1. After being fully premixed with the fuel gas, the mixed gas enters the gas chamber 3. The gas equalization plate 4 is a steel plate with regularly arranged round holes, which redistributes the mixed gas entering the gas chamber 3 evenly. After being evenly distributed by the gas equalization plate 4, the mixed gas is ignited and burned. The flame passes through the flame arrestor 6 and the flame stabilizer 7. In this embodiment, the flame stabilizer 7 is arranged in the inner flame section. The flame exchanges heat with the cooling water in the flame arrestor 6 and the flame stabilizer 7. A large amount of cooling water can efficiently remove heat and more effectively reduce the flame temperature, thereby reducing the generation of harmful gases such as NOx. In addition, the flame combustion is stable and the flame length is short, so there will be no backfire, deflagration, blockage, or flameout. Since the premixed combustion flame is short, the depth of the furnace can be reduced, thereby reducing the boiler volume and saving materials.

[0021] In this embodiment, a first gap is formed between two connected flame arrestor tubes 6, and a second gap is formed between two adjacent flame stabilizer tubes 7. The first gap and the second gap are used to allow the flame to pass through the flame arrestor tubes 6 and the flame stabilizer tubes 7.

[0022] The three first gaps formed between four adjacent flame arrestor tubes 6 correspond to the two second gaps formed between three adjacent flame stabilizer tubes 7, so that the positions of the first gaps and the second gaps are staggered. The flame passing through the first gaps can fully contact the surface of the flame stabilizer tube 7 and then pass through the second gaps, thereby improving the cooling effect on the flame.

[0023] The two first gaps formed between three adjacent flame arrestor tubes 6 correspond to a second gap formed between two adjacent flame stabilizer tubes 7. In this example, the flame stabilizer tube 7 has a larger diameter, allowing more cooling water to pass through and further reducing the flame combustion temperature. In this example, the positions of the first gap and the second gap are also staggered to ensure the contact effect between the flame and the surface of the flame stabilizer tube 7.

[0024] The flame arrestor tube 6 adopts a square core tube structure. The square core tube design of the flame arrestor tube 6 is suitable for situations where the furnace height is low, that is, the flame arrestor tube 6 is shorter, which allows more cooling water to flow inside the flame arrestor tube 6.

[0025] The flame arrestor tube 6 adopts a square core tube structure. The square core tube design of the flame arrestor tube 6 is suitable for situations where the furnace height is relatively high, that is, the flame arrestor tube 6 is relatively long. The square core tube design of the flame arrestor tube 6 has a thicker wall, a more stable structure, and stronger rigidity.

[0026] In this embodiment, the flame stabilizer tube 7 adopts a circular core tube structure. The diameter of the flame stabilizer tube 7 is larger than the length and width of the flame arrester tube 6, so that the number of flame stabilizer tubes 7 is less than the number of flame arrester tubes 6. It should be noted that in practical applications, the middle flame arrester tube 6 corresponds to the second gap between the two flame stabilizer tubes 7, and there can be slight vertical deviations. The required process precision in the actual production process does not need to be very high, and there is a high tolerance for error.

[0027] In this embodiment, a mounting frame 801 is fixedly connected to the outside of the blower 1, and mounting feet 802 are fixedly connected to the left and right ends of the bottom of the upper and lower water chambers 5. The bottom of the mounting frame 801 and the mounting feet 802 are fixedly connected to the base 8 by multiple sets of bolts. A drive motor 803 is fixedly installed at the front end of the top of the base 8. The drive end of the drive motor 803 is connected to the shaft of the blower 1 through a pulley set 804. The drive motor 803 transmits power to the shaft of the blower 1 through the pulley set 804, driving the blower 1 to run and realize the intake and delivery of external air. The blower 1 pressurizes the air into the mixer 2 and premixes it with the gas to form a uniform mixed gas, which is then sent into the gas chamber 3. The blower 1 is fixed to the base 8 by bolts through the mounting frame 801 to ensure operational stability. The upper and lower water chambers 5 are rigidly connected to the base 8 through the mounting feet 802 on both sides to form an overall support frame.

[0028] In this embodiment, connecting columns 901 are fixedly connected to the four corners of the bottom of the base 8, and the bottom ends of multiple sets of connecting columns 901 are slidably connected to the vibration damping box 9. Inside the vibration damping box 9 and at the bottom of the connecting columns 901, a lifting plate 902 is fixedly connected. Connecting heads 903 are fixedly connected to the four corners of the bottom of the lifting plate 902. The bottom ends of multiple sets of connecting heads 903 are hinged to linkage rods 904, and the bottom ends of multiple sets of linkage rods 904 are hinged to sliding sleeves 905. Multiple sets of sliding sleeves 905 are slidably connected to the bottom of the inside of the vibration damping box 9 through sliding rods 906. Buffer springs 907 are sleeved on the outer sides of multiple sets of sliding rods 906. Multiple sets of dampers 908 are fixedly installed between the bottom of the lifting plate 902 and the vibration damping box 9. When the base 8 vibrates due to the operation of the combustion device, the vibration is transmitted to the inside of the vibration damping box 9 through the connecting columns 901 at the four corners, and the bottom ends of the connecting columns 901 push the lifting plate 902. The downward movement of the connecting head 903 and the hinged linkage rod 904 causes the linkage rod 904 to move. The linkage rod 904 drives the sliding sleeve 905 to slide along the sliding rod 906, compressing the buffer spring 907 to absorb impact energy. Multiple dampers 908 work together to suppress the reciprocating motion amplitude of the lifting plate 902, achieving vibration attenuation. After the vibration weakens, the buffer spring 907 releases its elastic potential energy, pushing the sliding sleeve 905 back to its original position. The linkage rod 904 then drives the lifting plate 902 back to its initial position. The hinged design of the linkage rod 904 allows for multi-directional displacement compensation, avoiding stress concentration caused by rigid connections. The fixed connection between the lifting plate 902 and the connecting column 901 ensures a clear vibration transmission path and prevents structural loosening. The combined design of the buffer spring 907 and the damper 908 can absorb high-frequency vibrations and low-frequency swaying, reducing the risk of resonance. At the same time, the sliding structure of the sliding rod 906 and the sliding sleeve 905 reduces frictional loss and improves vibration reduction efficiency.

[0029] In this embodiment, rubber sealing rings 909 are fixedly connected to the connection points between the vibration damping box 9 and multiple sets of connecting columns 901. Stabilizing plates 910 are fixedly connected to both ends of the bottom of the lifting plate 902. Stabilizing wheels 911 are rotatably connected to both ends of the stabilizing plates 910, and the stabilizing wheels 911 are in contact with the inner wall of the vibration damping box 9. When the connecting columns 901 vibrate with the base 8, the rubber sealing rings 909 absorb high-frequency vibrations through elastic deformation, while simultaneously preventing dust or liquid from entering the vibration damping box 9. This isolates vibrations and protects the internal mechanisms of the vibration damping box 9 from contamination or... Corrosion is prevented and service life is extended. When the lifting plate 902 is pressed down by vibration, the stabilizing plate 910 drives the stabilizing wheel 911 to roll along the inner wall of the vibration damping box 9, which limits the lateral displacement of the lifting plate 902. The rolling friction of the stabilizing wheel 911 replaces the sliding friction, reducing motion resistance and ensuring the stability of the vertical movement trajectory of the lifting plate 902. In conjunction with the buffer spring 907 and the damper 908, a multi-stage vibration damping system is formed, which further suppresses the transmission of residual vibration to the external structure. It is suitable for high and low load conditions, and can maintain stable operation, especially in the resonant frequency band, to ensure the long-term reliability of the boiler.

[0030] Implementation Scheme: During operation, the drive motor 803 transmits power to the shaft of the blower 1 via the pulley assembly 804, driving the blower 1 to operate and achieve the intake and delivery of external air. The blower 1 compresses the air into the mixer 2 to premix it with the combustion gas, forming a uniform gas mixture, which is then sent into the gas chamber 3. After the gas mixture is evenly distributed through the gas equalization plate 4, it is ignited and burned. The flame passes through the first gap between multiple flame arrestor tubes 6, then contacts the surface of the flame stabilizer tube 7 and passes through the second gap between the flame stabilizer tubes 7. The flame arrestor tubes 6 and the flame stabilizer tubes 7 are connected to the upper and lower water chambers 5, allowing cooling water to circulate in the flame arrestor tubes 6 and the flame stabilizer tubes 7. Through heat exchange between the flame and the cooling water in the flame arrestor tube 6 and the flame stabilizer tube 7, a large amount of cooling water can efficiently remove heat, more effectively reducing the flame temperature and thus reducing the generation of harmful gases such as NOx. Furthermore, the flame combustion is stable and short, preventing backfire, deflagration, blockage, and flameout. Because the premixed combustion flame is shorter, the furnace depth can be reduced, thereby shrinking the boiler volume and saving materials. When the base 8 vibrates due to the operation of the combustion device, the vibration is transmitted to the vibration damping box 9 through the connecting columns 901 at the four corners. The bottom of the connecting columns 901 pushes the lifting plate 902 downwards, driving the connecting head 9... 03 and the hinged linkage 904 move, the linkage 904 drives the sliding sleeve 905 to slide along the sliding rod 906, compressing the buffer spring 907 to absorb impact energy. Multiple dampers 908 work together to suppress the reciprocating motion amplitude of the lifting plate 902, achieving vibration attenuation. After the vibration weakens, the buffer spring 907 releases elastic potential energy, pushing the sliding sleeve 905 back to its original position. The linkage 904 drives the lifting plate 902 to return to its initial position. When the connecting column 901 vibrates with the base 8, the rubber sealing ring 909 absorbs high-frequency vibration through elastic deformation, while preventing dust or liquid from entering the vibration damping box 9, thus isolating vibration. It also protects the internal structure of the vibration damping box 9 from contamination or corrosion, extending its service life. When the lifting plate 902 is pressed down by vibration, the stabilizing plate 910 drives the stabilizing wheel 911 to roll along the inner wall of the vibration damping box 9, limiting the lateral displacement of the lifting plate 902. The rolling friction of the stabilizing wheel 911 replaces the sliding friction, reducing motion resistance and ensuring the stability of the vertical movement trajectory of the lifting plate 902. Together with the buffer spring 907 and the damper 908, it forms a multi-stage vibration damping system, further suppressing the transmission of residual vibration to the external structure. It is suitable for high and low load conditions, and can maintain stable operation, especially in the resonant frequency band, ensuring the long-term reliability of the boiler.

[0031] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Clearly, those skilled in the art can make various alterations and variations to the invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of equivalents of the invention, the invention is also intended to include these modifications and variations.

Claims

1. A water-cooled premixed combustion device, characterized in that, include: mixer; The blower's outlet is fixedly connected to the mixer's inlet; The air chamber is fixedly connected to the air outlet of the mixer; The gas equalization orifice plate is fixedly connected to the inside of the gas chamber near the mixer. The gas equalization orifice plate consists of regularly arranged round holes in a whole steel plate. Flame arrestor tubes are fixedly connected to the inside of the gas chamber and located on the side of the gas equalization plate away from the mixer. Several flame arrestor tubes are arranged in parallel at equal intervals along the vertical direction inside the gas chamber. The flame arrestor tubes adopt a square core tube or a square round core tube structure. Flame stabilizers are fixedly connected to the inside of the gas chamber and located on the side of the flame arrestor tube away from the gas equalization plate. Several flame stabilizers are arranged in parallel at equal intervals along the vertical direction inside the gas chamber. The flame stabilizers adopt a circular core tube structure, and the diameter of the flame stabilizer tube is greater than the length and width of the flame arrestor tube. A first gap is formed between two connected flame arrestor tubes, and a second gap is formed between two adjacent flame stabilizer tubes. The first gap and the second gap are staggered. The three first gaps formed between four adjacent flame arresters correspond to the two second gaps formed between three adjacent flame stabilizers. The two first gaps formed between three adjacent flame arresters correspond to the one second gap formed between two adjacent flame stabilizers. The upper and lower water chambers are located at the top and bottom of the gas chamber, and the flame arrestor pipe and flame stabilizer pipe are connected to the upper and lower water chambers. The base is fixedly installed at the bottom of the blower and the water inlet and outlet chambers, and a vibration damping box is movably installed at the bottom of the base. Connecting columns are fixedly connected to the four corners at the bottom of the base, and the bottom ends of multiple sets of connecting columns are slidably connected to the vibration damping box. Inside the vibration damping box and at the bottom of the connecting columns, a lifting plate is fixedly connected. Connecting heads are fixedly connected to the four corners at the bottom of the lifting plate. Linkage rods are hinged to the bottom ends of multiple sets of connecting heads. Sliding sleeves are hinged to the bottom ends of multiple sets of linkage rods. Sliding sleeves are slidably connected to the bottom of the vibration damping box through sliding rods. Buffer springs are sleeved on the outside of multiple sets of sliding rods. Multiple sets of dampers are fixedly installed between the bottom of the lifting plate and the vibration damping box. Rubber sealing rings are fixedly connected to the connection points between the inside of the vibration damping box and multiple sets of connecting columns. Stabilizing plates are fixedly connected to both ends of the bottom of the lifting plate. Stabilizing wheels are rotatably connected to both ends of the stabilizing plates, and the stabilizing wheels are in contact with the inner side wall of the vibration damping box.

2. The water-cooled premixed combustion device according to claim 1, characterized in that, A mounting frame is fixedly connected to the outside of the blower. Mounting feet are fixedly connected to the left and right ends of the bottom of the upper and lower water chambers. The bottom of the mounting frame and the mounting feet are fixedly connected to the base by multiple sets of bolts. A drive motor is fixedly installed at the front end of the top of the base. The drive end of the drive motor is connected to the shaft of the blower through a pulley set.

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