A waste heat recovery device for boiler flue gas

Abstract

This utility model proposes a waste heat recovery device for boiler flue gas, relating to flue gas waste heat recovery technology. Specifically, it discloses a shell and hot air inlet / outlet pipes. The hot air inlet / outlet pipes are installed on one side of the shell, and an exhaust pipe is installed on the other side of the shell. A shaft is rotatably provided inside the shell, and several inclined fan plates are arranged around the outer wall of the shaft. Each fan plate has a first chamber. A second chamber communicating with the first chamber is provided inside the shaft. Several contact points are provided on the outer wall of each fan plate. Several heat-conducting pipes corresponding to the contact points are located in the first chamber, with the cold end of the heat-conducting pipe abutting against the contact point. A return air pipe is provided on the outer wall of the exhaust pipe, and the hot end of the heat-conducting pipe is embedded in the return air pipe. After the flue gas enters the shell, it impacts the inclined fan plates and drives the shaft to rotate, forcing the flue gas to flow along a spiral path, significantly increasing the heat exchange time.

Description

Technical Field

[0001] This utility model relates to the field of flue gas waste heat recovery technology, and more specifically, to a waste heat recovery device for boiler flue gas. Background Technology

[0002] Air preheaters are widely used in boiler systems of thermal power plants. They are designed to preheat the air entering the boiler by recovering heat from the flue gas, thereby improving the boiler's thermal efficiency, reducing energy consumption, and reducing pollutant emissions. The main principle is to use the residual heat in the flue gas to heat the air entering the boiler. They are usually divided into two types of airflow: primary air and secondary air.

[0003] In existing rotary air preheaters, the heat storage plates typically employ a fixed design. These corrugated heat storage plates, due to their large surface area and unique geometry, can effectively absorb heat from the flue gas. When the flue gas flows through the corrugated heat storage plates, heat is conducted into the air, thus achieving heat exchange. However, although the corrugated shape helps improve heat exchange efficiency, when the heat storage plates come into contact with primary air, most of the heat in the heat storage plates is transferred to the primary air through conduction, causing the primary air temperature to rise rapidly. This results in a significant decrease in heat transfer efficiency when the heat storage plates come into contact with secondary air; the amount of heat transferred is far less than that of the primary air, leading to an insignificant heating effect in the secondary air, which in turn affects the boiler's combustion efficiency and overall thermal efficiency. Utility Model Content

[0004] The purpose of this utility model is to provide a waste heat recovery device for boiler flue gas, which addresses the shortcomings of the existing technology and solves the problems mentioned in the background.

[0005] The technical solution of this utility model is implemented as follows: This utility model provides a waste heat recovery device for boiler flue gas, including a shell and a hot air inlet and outlet pipe. The hot air inlet and outlet pipe is installed on one side of the shell, and an exhaust pipe is installed on the other side of the shell. The housing has a rotating shaft, and several inclined fan plates are arranged around the outer wall of the shaft. Each fan plate has a first chamber. The shaft has a second chamber that communicates with the first chamber. Each fan plate has several contact points on its outer wall. The first chamber contains several heat-conducting tubes that correspond one-to-one with the contacts. The cold end of the heat-conducting tube abuts against the contacts. A return air duct is provided on the outer wall of the exhaust duct, and the hot end of the heat-conducting tube is embedded in the return air duct.

[0006] In some technical solutions of this utility model, the fan plate is arc-shaped, and the outer arc surface of the fan plate is opposite to the inner arc surface of another adjacent fan plate.

[0007] In some technical solutions of this utility model, one end of the shaft is provided with an inlet communicating with the second chamber, and the other end of the shaft is provided with an outlet communicating with the second chamber.

[0008] In some technical solutions of this utility model, an installation port is provided on one side of the fan plate, and a first drive motor is embedded in the installation port. The output end of the first drive motor is connected to the outer wall of the shaft.

[0009] In some technical solutions of this utility model, the hot air inlet and outlet pipes are installed at an angle on one side of the housing, and the reverse extension line of the hot air inlet and outlet pipes is tangent to the circle in which the housing is located.

[0010] In some technical solutions of this utility model, a number of mounting seats corresponding to the fan plates are arranged around the outer side wall of the shaft. A rotating seat is rotatably arranged inside the mounting seat. A second drive motor that is connected to the rotating seat is arranged inside the mounting seat. The output end of the first drive motor is connected to the rotating seat.

[0011] In some technical solutions of this utility model, a first solenoid valve is provided at the connection between the hot air inlet / outlet pipe and the shell.

[0012] In some technical solutions of this utility model, a second solenoid valve is provided at the connection between the return air duct and the exhaust air duct.

[0013] Compared to existing technologies, this invention has at least the following advantages or beneficial effects: After the flue gas enters the casing, it impacts the inclined fan plate, driving the shaft to rotate and forcing the flue gas to flow along a spiral path (the optimized arc-shaped fan plate further extends the path), significantly increasing the heat exchange time. Combined with the increased contact area (heat-conducting material) on the fan plate, heat is efficiently transferred to the cold end of the heat pipe through the contacts. The working fluid inside the heat pipe absorbs the heat, and the hot end is placed in the first chamber, directly heating the low-temperature medium (such as air or water) in the return air duct. This achieves flue gas temperature recovery, and the recovered heat energy can be used across spaces for preheating boiler intake, heating, or industrial processes. The overall heat recovery rate is high, and the flue gas enters the casing tangentially (the hot air inlet and outlet pipes are installed at an angle, with the reverse extension line tangential to the casing), maximizing the use of flue gas kinetic energy to drive the fan plate rotation, reducing eddies and resistance, and lowering the dependence on auxiliary fan power. Attached Figure Description

[0014] Figure 1 This is a front view schematic diagram of the structure of this utility model.

[0015] Figure 2 This is a schematic diagram of the internal structure of the shell in this utility model.

[0016] Figure 3 This is a top view of the shell structure in this utility model.

[0017] Figure 4This is a schematic diagram of the internal structure of the shaft and the fan plate of this utility model.

[0018] Reference numerals in the attached drawings: 1. Hot air inlet / outlet pipe; 2. Housing; 3. Exhaust pipe; 4. Return air pipe; 5. Heating jacket; 6. First solenoid valve; 7. Second solenoid valve; 8. Shaft; 9. Partition plate; 10. Fan plate; 11. Second chamber; 12. First chamber; 13. Contact point; 14. Heat conduction pipe; 15. First drive motor; 16. Mounting base; 17. Rotating base; 18. Second drive motor. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0021] Example This utility model provides a waste heat recovery device for boiler flue gas, such as... Figures 1-4 As shown, it includes a housing 2 and a hot air inlet / outlet pipe 1. The hot air inlet / outlet pipe 1 is installed on one side of the housing 2. High-temperature flue gas enters the housing 2 from the hot air inlet / outlet pipe 1 and is discharged from the exhaust pipe 3 installed on the other side of the housing 2. A shaft 8 is rotatably mounted within the housing 2 via bearings. Two bearings are installed on opposite sides of the shaft 8. Several inclined fan plates 10 are arranged around the outer wall of the shaft 8, spirally or annularly distributed. When high-temperature flue gas enters the housing 2 from the hot air inlet / outlet pipe 1, it impacts the inclined fan plates 10, driving the shaft 8 to rotate and prolonging the residence time of the flue gas within the housing 2. Each fan plate 10 has a first chamber 12, which is fan-shaped. A second chamber 11 communicating with the first chamber 12 is located within the shaft 8. Several contact points 13 are provided on the outer wall of each fan plate 10, increasing the contact area between the flue gas and the fan plate 10. The contact points 13 are made of a highly thermally conductive material. Several heat-conducting pipes 14, each corresponding to a contact 13, are located in the first chamber 12. The cold end of the heat-conducting pipe 14 abuts against the contact 13. The flue gas comes into contact with the contact 13 on the surface of the fan plate 10, and the heat is transferred to the cold end of the heat-conducting pipe 14 through the contact 13. The working fluid in the heat-conducting pipe 14 absorbs the heat, thereby transferring the heat energy to the hot end, realizing the recovery and utilization of heat in the flue gas.

[0022] A return air duct 4 is provided on the outer wall of the exhaust duct 3. The hot end of the heat-conducting pipe 14 is placed in the first chamber 12. The hot end of the heat-conducting pipe 14 heats the low-temperature medium (such as air or water) flowing through the return air duct 4. A portion of the flue gas discharged from the exhaust duct 3 re-enters the hot air inlet / outlet duct 1 through the return air duct 4 for recycling. The above structure utilizes the kinetic energy of the flue gas to drive the fan plate 10 to rotate, achieving efficient heat conduction through physical contact (contact point 13). The heat-conducting pipe 14 forms a closed heat conduction path, transferring the waste heat of the flue gas across space to the low-temperature medium in the return air duct 4, thereby achieving energy recovery and reuse.

[0023] The hot end of the heat pipe 14 is placed in the first chamber 12, and the end of the shaft 8 is rotatably provided with a heating sleeve 5. The heating sleeve 5 is installed on the outside of the return air pipe 4 and acts to circulate and heat the air medium in the return air pipe 4.

[0024] In some technical solutions of this utility model, the fan plate 10 is arc-shaped, and the outer arc surface of the fan plate 10 is opposite to the inner arc surface of the adjacent fan plate 10. The arc-shaped fan plate 10 optimizes the gas flow direction, prolongs the residence time of flue gas in the shell 2, increases the heat exchange time, and when rotating, the arc surfaces of adjacent fan plates 10 form a continuous guide surface, guiding the flue gas to flow along a spiral path, effectively improving the waste heat recovery rate (reduced flue gas velocity + prolonged contact time) and reducing eddy current resistance.

[0025] In some technical solutions of this utility model, one end of the shaft 8 is provided with a water inlet communicating with the second chamber 11, and the other end of the shaft 8 is provided with a water outlet communicating with the second chamber 11. Coolant is injected into the inner cavity of the shaft 8 through the water inlet, flows through the first chamber 12 of the fan plate 10, and is discharged from the water outlet. The liquid cooling circulation system absorbs the heat conducted by the contact 13 through the liquid working medium, enhances the ability to recover heat, and the use of both gas and liquid media for circulating heat absorption can prevent the fan plate 10 from overheating and deforming, improve system stability, and also allow the heated cooling medium to be recycled for use in other processes.

[0026] In some technical solutions of this utility model, a mounting port is provided on one side of the fan blade 10, and a first drive motor 15 is embedded in the mounting port. The output end of the first drive motor 15 is connected to the outer wall of the shaft 8. When the flue gas power is insufficient, the first drive motor 15 actively drives the fan blade 10 to rotate to maintain heat exchange. The motor assists in overcoming the starting resistance under low load conditions, ensuring continuous operation of the system, and realizing that the contact points 13 on both sides of the fan blade are in continuous contact with the flue gas, thereby improving heat exchange efficiency and avoiding shutdown due to flue gas flow fluctuations. Furthermore, the drive motor can also adjust the deflection angle of the fan blade 10 to increase its contact area with the flue gas and increase its rotational speed.

[0027] In some technical solutions of this utility model, the hot air inlet / outlet pipe 1 is installed obliquely on one side of the housing 2, and the reverse extension line of the hot air inlet / outlet pipe 1 is tangent to the circle in which the housing 2 is located. The flue gas enters the housing 2 at a tangential angle, pushing the fan plate 10 to rotate in a fixed direction. Tangential air intake maximizes the utilization of flue gas kinetic energy, reduces turbulence loss, reduces drive energy consumption (naturally forming rotational force), and reduces fan power dependence.

[0028] In some technical solutions of this utility model, a plurality of mounting seats 16 corresponding one-to-one with the fan plates 10 are arranged around the outer wall of the shaft 8. A rotating seat 17 is rotatably arranged inside the mounting seat 16. The rotation direction of the rotating seat 17 is perpendicular to the rotation direction of the shaft 8. A second drive motor 18 is provided inside the mounting seat 16 and is drivenly connected to the rotating seat 17. The output end of the first drive motor 15 is connected to the rotating seat 17. The first drive motor 15 independently controls the angle of a single fan plate 10, adjusts the contact area with the flue gas, dynamically adjusts the tilt angle of the fan plate 10, and matches the optimal heat exchange posture under different flue gas flow rates.

[0029] In some technical solutions of this utility model, a first solenoid valve 6 is provided at the connection between the hot air inlet / outlet pipe 1 and the housing 2. The valve automatically opens and closes according to the flue gas temperature to control the amount of flue gas entering the housing 2, and the solenoid valve is interlocked with a temperature sensor to prevent the thermal efficiency from decreasing due to low-temperature flue gas.

[0030] In some technical solutions of this utility model, a second solenoid valve 7 is provided at the connection between the return air duct 4 and the exhaust air duct 3. The valve adjusts the flow rate of the medium in the return air duct 4 to maintain the optimal heat recovery temperature difference, and controls the flow rate of the return air medium to avoid excessive cooling of the flue gas from affecting subsequent processing.

[0031] Preferably, a plurality of partitions 9 are provided inside the housing 2, which divide the internal space of the housing 2 into multiple spaces, guide the flue gas circulation, and increase the efficiency of heat circulation. The shaft 8 passes through the partitions 9, and the fan plates 10 are evenly distributed in the above-mentioned spaces to increase the contact area between the fan plates and the flue gas.

[0032] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A waste heat recovery device for boiler flue gas, characterized in that, It includes a housing (2) and a hot air inlet / outlet pipe (1), the hot air inlet / outlet pipe (1) being installed on one side of the housing (2), and an exhaust pipe (3) being installed on the other side of the housing (2). The housing (2) is rotatably provided with a shaft (8), and a plurality of inclined fan plates (10) are arranged around the outer side wall of the shaft (8). Each fan plate (10) has a first chamber (12) inside it. The shaft (8) has a second chamber (11) that communicates with the first chamber (12). Each fan plate (10) has a plurality of contact points (13) on its outer side wall. The first chamber (12) contains several heat-conducting pipes (14) that correspond one-to-one with the contact points (13). The cold end of the heat-conducting pipe (14) abuts against the contact points (13). The outer wall of the exhaust pipe (3) is provided with a return air pipe (4). The hot end of the heat-conducting pipe (14) is placed in the first chamber (12). The end of the shaft (8) is rotatably provided with a heating sleeve (5). The heating sleeve (5) is installed on the outside of the return air pipe (4).

2. The waste heat recovery device for boiler flue gas according to claim 1, characterized in that, The fan plate (10) is arc-shaped, and the outer arc surface of the fan plate (10) is opposite to the inner arc surface of the adjacent fan plate (10).

3. The waste heat recovery device for boiler flue gas according to claim 1, characterized in that, One end of the shaft (8) is provided with an inlet that communicates with the second chamber (11), and the other end of the shaft (8) is provided with an outlet that communicates with the second chamber (11).

4. A waste heat recovery device for boiler flue gas according to claim 1 or 2, characterized in that, The fan plate (10) has an installation port on one side, and a first drive motor (15) is embedded in the installation port. The output end of the first drive motor (15) is connected to the outer wall of the shaft (8).

5. The waste heat recovery device for boiler flue gas according to claim 4, characterized in that, The hot air inlet / outlet pipe (1) is installed at an angle on one side of the housing (2), and the reverse extension line of the hot air inlet / outlet pipe (1) is tangent to the circle in which the housing (2) is located.

6. The waste heat recovery device for boiler flue gas according to claim 4, characterized in that, The outer wall of the shaft (8) is surrounded by a plurality of mounting seats (16) corresponding one-to-one with the fan plate (10). A rotating seat (17) is rotatably provided inside the mounting seat (16). A second drive motor (18) is provided inside the mounting seat (16) and is connected to the rotating seat (17) in a transmission. The output end of the first drive motor (15) is connected to the rotating seat (17).

7. The waste heat recovery device for boiler flue gas according to claim 1, characterized in that, A first solenoid valve (6) is provided at the connection between the hot air inlet / outlet pipe (1) and the housing (2).

8. The waste heat recovery device for boiler flue gas according to claim 1, characterized in that, A second solenoid valve (7) is provided at the connection between the return air duct (4) and the exhaust air duct (3).

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