Flue gas waste heat recovery device for flue gas air heater

Abstract

A flue gas waste heat recovery device for a flue gas heater, relating to the field of flue gas heater technology, includes an installation frame. The front end of the installation frame has multiple vertically distributed front pipes, each with a plurality of equidistantly distributed first heat exchange fins on its surface. The installation frame also has multiple vertically distributed middle pipes, each with a plurality of equidistantly distributed second heat exchange fins on its surface. The rear end of the installation frame has multiple equidistantly distributed rear pipes, each with a plurality of equidistantly distributed third heat exchange fins on its surface. All three heat exchange fins are inclined, and they are not only staggered but also inclined in opposite directions. This solution solves the problems of poor heat recovery efficiency and the inability to adaptively adjust to fluctuations in exhaust gas temperature in flue gas waste heat recovery devices.

Description

Technical Field

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

[0002] Flue gas preheaters are flue gas-air heat exchangers used in thermal power plants that operate on the principle of surface heat exchange. They are mainly composed of tubular heat exchangers, tube boxes and tube sheets, and shock-absorbing baffles, and are usually arranged vertically in rows. They heat the cold air entering the air preheater by recovering waste heat from the boiler exhaust, thereby increasing the inlet air temperature and outlet flue gas temperature of the air preheater. This effectively prevents the air preheater from being damaged by low-temperature corrosion and reduces the risk of blockage. At the same time, it can also improve the dust collection efficiency of electrostatic precipitators and reduce energy consumption. They are widely used in coal-fired power plant boiler systems that use rotary air preheaters and are important equipment for optimizing unit operation and improving energy utilization efficiency.

[0003] For example, the Chinese authorized patent CN201103918Y, entitled "A Flue Gas Waste Heat Recovery Heater", includes: multiple parallel metal plates, with an air channel or flue gas channel formed between each pair of adjacent metal plates. The air channel and flue gas channel are arranged alternately, with the air inlet direction at 90° to the flue gas inlet direction and the gas outlet direction consistent with the inlet direction. Both sides of the gas channel are provided with sealing aluminum strips parallel to the air or flue gas flow direction.

[0004] While the aforementioned existing technologies achieve waste heat recovery, the small contact area between the high-temperature flue gas and the heat exchange structure during the waste heat recovery process leads to poor heat recovery efficiency. Furthermore, the boiler exhaust temperature fluctuates in real time due to factors such as coal quality, load changes, and combustion conditions. If the heat exchange medium flow rate is fixed, it results in insufficient heat exchange at low flue gas temperatures and excessive heat exchange at high flue gas temperatures, thus failing to meet current requirements. Therefore, we propose a flue gas waste heat recovery device using a flue gas heater. Utility Model Content

[0005] The purpose of this utility model is to provide a flue gas waste heat recovery device for a flue gas heater, so as to solve the problems mentioned in the background art, such as poor heat recovery efficiency and inability to adaptively adjust according to fluctuations in exhaust gas temperature.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a flue gas heater waste heat recovery device, comprising an installation frame, wherein the front end of the installation frame is provided with multiple vertically distributed front pipes, the surface of the front pipes is provided with multiple equidistantly distributed first heat exchange plates, and the upper and lower first heat exchange plates are staggered; the interior of the installation frame is provided with multiple vertically distributed middle pipes, the surface of the middle pipes is provided with multiple equidistantly distributed second heat exchange plates, and the upper and lower second heat exchange plates are staggered; the rear end of the installation frame is provided with multiple equidistantly distributed rear pipes, the surface of the rear pipes is provided with multiple equidistantly distributed third heat exchange plates, and the upper and lower third heat exchange plates are staggered; the first, second, and third heat exchange plates are all inclined structures, and the first, second, and third heat exchange plates are not only staggered, but their inclination directions are also opposite to each other.

[0007] Preferably, the multiple front pipes, the multiple intermediate pipes, and the multiple rear pipes are connected by connecting pipes.

[0008] Preferably, the outlet end of the channel formed by the plurality of front pipes and the inlet end of the channel formed by the plurality of intermediate pipes, as well as the outlet end of the channel formed by the plurality of intermediate pipes and the inlet end of the channel formed by the plurality of rear pipes, are connected by a diversion pipe.

[0009] Preferably, a medium inlet pipe is installed at the inlet end of the channel formed by the multiple front pipes, and a medium outlet pipe is installed at the outlet end of the channel formed by the multiple rear pipes.

[0010] Preferably, a flow regulating valve is installed outside the medium inlet pipe, and the input end of the flow regulating valve is connected to the controller. A temperature sensor is installed at the lower end of the medium outlet pipe, and the output end of the temperature sensor is connected to the input end of the controller.

[0011] Preferably, flanges are welded and fixed to the outer ends of the medium inlet pipe and the medium outlet pipe.

[0012] Preferably, the bottom of the mounting frame is provided with a connecting base.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] 1. This utility model sets up three sets of heat exchange pipes in the installation frame. Multiple equally spaced and inclined heat exchange fins are provided on the outside of the heat exchange pipes. The heat exchange fins on the upper and lower heat exchange pipes are staggered, and the heat exchange fins on the front and rear heat exchange pipes are not only staggered but also inclined in opposite directions. This causes the flue gas to not flow in a straight line after entering the waste heat recovery device, but to move in an S-shape along the staggered and inclined heat exchange fins. This prolongs the residence time of the flue gas in the device, greatly increasing the contact area and duration between the flue gas and the heat exchange pipes and fins, thereby significantly improving the waste heat recovery efficiency. The staggered and inclined heat exchange fin structure changes the flow direction of the flue gas, creating a disturbance effect, disrupting the flue gas boundary layer, strengthening the heat transfer process, and further enhancing the heat exchange effect. At the same time, the S-shaped flow path of the flue gas makes the airflow distribution more uniform, avoiding local overheating or uneven heat exchange, and effectively reducing the risk of damage to the equipment due to uneven heating.

[0015] 2. This utility model installs a temperature sensor on the medium outlet pipe and a flow regulating valve on the medium inlet pipe. The temperature sensor can accurately capture the temperature changes of the medium outlet pipe in real time and quickly feed the data back to the control system. The flow regulating valve then dynamically adjusts the flow rate of the medium inlet pipe accordingly. When the boiler is operating at high load and the flue gas temperature rises, the sensor detects the increase in medium temperature, and the flow regulating valve automatically increases the medium flow rate to enhance the heat exchange process, fully recover waste heat, and avoid overheating of the medium or overload of the equipment due to excessive heat exchange. Conversely, when the boiler is operating at low load and the flue gas temperature decreases, the sensor sends a low-temperature signal, and the flow regulating valve immediately reduces the medium flow rate to ensure sufficient heat exchange between the medium and the flue gas, preventing insufficient heat exchange and inadequate waste heat recovery. The two components work together to form an intelligent dynamic closed-loop control system, allowing the waste heat recovery device to adapt to changes in flue gas temperature under different operating conditions, maintaining efficient and stable operation at all times. This improves energy utilization efficiency, reduces the risk of equipment damage due to abnormal temperature, and extends the service life of the equipment. Attached Figure Description

[0016] Figure 1 This is a perspective view of the present utility model;

[0017] Figure 2 This is another perspective view of the present invention;

[0018] Figure 3 This is a schematic diagram of the pipe fin distribution structure of this utility model;

[0019] Figure 4 This is a schematic diagram of the waste heat recovery and regulation principle of this utility model.

[0020] In the diagram: 1. Mounting frame; 2. Front pipe; 3. First heat exchanger; 4. Connecting pipe; 5. Medium inlet pipe; 6. Flow regulating valve; 7. Medium outlet pipe; 8. Temperature sensor; 9. Flange; 10. Diverting pipe; 11. Intermediate pipe; 12. Rear pipe; 13. Second heat exchanger; 14. Third heat exchanger. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0022] Please see Figure 1-4 This utility model provides an embodiment of a flue gas heater waste heat recovery device, including an installation frame 1. The bottom of the installation frame 1 is provided with a connecting base. The front end of the installation frame 1 is provided with multiple vertically distributed front pipes 2. The surface of the front pipes 2 is provided with multiple equidistantly distributed first heat exchange plates 3, and the upper and lower first heat exchange plates 3 are staggered. The interior of the installation frame 1 is provided with multiple vertically distributed middle pipes 11. The surface of the middle pipes 11 is provided with multiple equidistantly distributed second heat exchange plates 13, and the upper and lower second heat exchange plates 13 are staggered. The rear end of the installation frame 1 is provided with multiple equidistantly distributed rear pipes 12. The surface of the rear pipes 12 is provided with multiple equidistantly distributed third heat exchange plates 14, and the upper and lower third heat exchange plates 14 are staggered. The first heat exchange plates 3, the second heat exchange plates 13, and the third heat exchange plates 14 are all inclined structures, and the first heat exchange plates 3, the second heat exchange plates 13, and the third heat exchange plates 14 are not only staggered, but also have opposite inclination directions.

[0023] When the flue gas enters the mounting frame 1, due to the staggered and inclined structure of the first heat exchanger fin 3, the second heat exchanger fin 13, and the third heat exchanger fin 14, the flue gas cannot pass in a straight line. Instead, it flows in an S-shaped tortuous manner between different pipes along the inclined direction of the heat exchanger fins. During this process, the flue gas makes full contact with the front pipe 2, the middle pipe 11, the rear pipe 12, and the heat exchanger fins on their surfaces. Through heat conduction and convection, the flue gas transfers the heat it carries to the heat exchange medium inside the pipes. This design greatly extends the residence time of the flue gas in the device, significantly increases the contact area between the flue gas and the pipes and heat exchanger fins, enhances the heat transfer effect, and effectively improves the waste heat recovery efficiency. At the same time, the S-shaped flow of the flue gas can also generate disturbance, disrupt the flue gas boundary layer, further enhance heat transfer, and make the airflow distribution more uniform, avoiding local overheating or uneven heat transfer, and reducing the risk of equipment damage caused by uneven heating. In addition, the inclined heat exchanger fins can utilize gravity to cause dust and other impurities in the flue gas to slide off and be discharged, reducing the probability of dust accumulation and blockage, lowering equipment maintenance costs, and ensuring long-term stable operation of the device.

[0024] Please see Figure 1 and Figure 2 Multiple front pipes 2, multiple intermediate pipes 11, and multiple rear pipes 12 are connected by connecting pipes 4. The outlet end of the channel formed by the multiple front pipes 2 and the inlet end of the channel formed by the multiple intermediate pipes 11, as well as the outlet end of the channel formed by the multiple intermediate pipes 11 and the inlet end of the channel formed by the multiple rear pipes 12, are connected by diverting pipes 10. This pipe connection method allows the heat exchange medium to flow orderly within the device, fully covering the entire heat exchange area and ensuring comprehensive, multi-level heat exchange between the medium and the flue gas, maximizing the absorption of waste heat from the flue gas. By rationally arranging the connecting pipes 4 and diverting pipes 10, the flow path of the medium is optimized, improving the heat exchange efficiency of the medium, thereby enhancing the energy utilization rate of the entire waste heat recovery device, while ensuring a compact structure for easy installation and maintenance.

[0025] Please see Figure 1 and Figure 4 A medium inlet pipe 5 is installed at the inlet end of a channel formed by multiple front pipes 2, and a medium outlet pipe 7 is installed at the outlet end of a channel formed by multiple rear pipes 12. Flanges 9 are welded and fixed to the outer ends of the medium inlet pipe 5 and the medium outlet pipe 7. A flow regulating valve 6 is installed outside the medium inlet pipe 5, and the input end of the flow regulating valve 6 is connected to the controller. A temperature sensor 8 is installed at the lower end of the medium outlet pipe 7, and the output end of the temperature sensor 8 is connected to the input end of the controller. The temperature sensor 8 monitors the temperature of the medium in the medium outlet pipe 7 in real time and converts the temperature data into an electrical signal, which is then transmitted to the controller. The controller issues control commands to the flow regulating valve 6 based on the preset temperature range and the received temperature signal. When the boiler flue gas temperature rises, causing the medium temperature in the medium outlet pipe 7 to rise, the controller controls the flow regulating valve 6 to increase its opening, increasing the medium flow rate in the medium inlet pipe 5, allowing more medium to participate in heat exchange and absorb more heat. When the flue gas temperature decreases, causing the medium temperature to drop, the controller controls the flow regulating valve 6 to decrease its opening, reducing the medium flow rate and ensuring sufficient heat exchange between the medium and the flue gas. This system achieves dynamic and intelligent regulation of the heat exchange process through the linkage of temperature sensors and flow control valves, effectively solving the problem of insufficient or excessive heat exchange caused by fluctuations in boiler flue gas temperature. Regardless of whether the boiler is operating at high or low load, the device can adaptively adjust, always maintaining a high and stable waste heat recovery efficiency. This avoids energy waste at low flue gas temperatures and prevents medium overheating or equipment overload at high flue gas temperatures, ensuring safe and stable equipment operation and extending equipment lifespan.

[0026] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A flue gas waste heat recovery device for a flue gas heater, comprising an installation frame (1), characterized in that: The front end of the mounting frame (1) is provided with multiple vertically distributed front pipes (2). The surface of the front pipes (2) is provided with multiple equidistant first heat exchange plates (3), and the upper and lower first heat exchange plates (3) are staggered. The interior of the mounting frame (1) is provided with multiple vertically distributed middle pipes (11). The surface of the middle pipes (11) is provided with multiple equidistant second heat exchange plates (13), and the upper and lower second heat exchange plates (13) are staggered. The rear end of the mounting frame (1) is provided with multiple equidistant rear pipes (12). The surface of the rear pipes (12) is provided with multiple equidistant third heat exchange plates (14), and the upper and lower third heat exchange plates (14) are staggered. The first heat exchange plates (3), the second heat exchange plates (13) and the third heat exchange plates (14) are all inclined structures. The first heat exchange plates (3), the second heat exchange plates (13) and the third heat exchange plates (14) are not only staggered, but their inclination directions are also opposite to each other.

2. The flue gas waste heat recovery device for a flue gas heater according to claim 1, characterized in that: The multiple front pipes (2), the multiple intermediate pipes (11), and the multiple rear pipes (12) are connected by a connecting pipe (4).

3. The flue gas waste heat recovery device for a flue gas heater according to claim 2, characterized in that: The outlet end of the channel formed by the multiple front pipes (2) and the inlet end of the channel formed by the multiple intermediate pipes (11), as well as the outlet end of the channel formed by the multiple intermediate pipes (11) and the inlet end of the channel formed by the multiple rear pipes (12) are connected by a turning pipe (10).

4. The flue gas waste heat recovery device for a flue gas heater according to claim 3, characterized in that: A medium inlet pipe (5) is installed at the inlet end of a channel formed by connecting multiple front pipes (2), and a medium outlet pipe (7) is installed at the outlet end of a channel formed by connecting multiple rear pipes (12).

5. The flue gas waste heat recovery device for a flue gas heater according to claim 4, characterized in that: A flow regulating valve (6) is installed on the outside of the medium inlet pipe (5), and the input end of the flow regulating valve (6) is connected to the controller. A temperature sensor (8) is installed at the lower end of the medium outlet pipe (7), and the output end of the temperature sensor (8) is connected to the input end of the controller.

6. The flue gas waste heat recovery device for a flue gas heater according to claim 4, characterized in that: Flanges (9) are welded and fixed to the outer ends of the medium inlet pipe (5) and the medium outlet pipe (7).

7. The flue gas waste heat recovery device for a flue gas heater according to claim 1, characterized in that: The bottom of the mounting frame (1) is provided with a connecting base.

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