Flue gas recirculation conveying air pipe for large-scale thermal power plant

Abstract

The utility model discloses a flue gas recirculation conveying air pipe for a large-scale thermal power plant, which comprises a first conveying air pipe, the left end flange of the first conveying air pipe is connected with a connecting pipe, the rear end of the connecting pipe is communicated with an air inlet pipe, and the rear end flange of the air inlet pipe is connected with a second conveying air pipe; a mounting ring is attached between the connecting pipe and the first conveying air pipe, a supporting rod is connected to the inner wall of the mounting ring, and a mounting plate is mounted at the end of the supporting rod. According to the flue gas recirculation conveying air pipe for the large-scale thermal power plant, the speed of flue gas can be preliminarily slowed down through obstruction of the buffer fan blades, the inner diameter of the right section part of the first conveying air pipe is gradually increased, so that the speed of flowing flue gas can be gradually slowed down again, the air speed of recirculation air is reduced on the premise that enough recirculation air volume is guaranteed, and the energy consumption is reduced. The interference on ignition of pulverized coal at an outlet of the combustor is reduced, and the influence on normal combustion of the pulverized coal can be effectively avoided while parameter adjustment of the boiler is not influenced.

Description

Technical Field

[0001] This utility model relates to the field of thermal power generation technology, specifically to a flue gas recirculation conveying duct for large thermal power plants. Background Technology

[0002] The flue gas system in a thermal power plant is a critical system and an essential component of the combustion system for maintaining the normal operation of the boiler. Supercritical generator sets recirculate a portion of the flue gas back into the boiler, allowing it to mix with fuel for secondary combustion, releasing more heat energy and improving the boiler's thermal efficiency. In addition, flue gas recirculation can reduce the radiative heat transfer in the furnace and increase the heat transfer on the convective heating surfaces, thereby increasing the reheat steam temperature. It can also reduce the oxygen concentration in the furnace, thus reducing NOx emissions.

[0003] Currently, the common flue gas recirculation method in power plants involves extracting a portion of the flue gas from the economizer, pressurizing it with a flue gas recirculation fan, transporting it through a recirculation conveying duct, and then re-entering the furnace through nozzles located at the bottom of the burner. The amount of flue gas participating in the recirculation can be controlled by changing the speed of the flue gas recirculation fan and the opening of the recirculation air nozzle regulating valve, according to actual needs. Since the flue gas recirculation air nozzles are located at the bottom of the burner, when the recirculation air velocity is too high, it can easily interfere with the normal combustion of pulverized coal at the burner outlet. In severe cases, it can cause poor ignition of pulverized coal in the lower layer of the burner or even the risk of flameout.

[0004] Therefore, we propose a flue gas recirculation conveying duct for large thermal power plants to solve the problems mentioned above. Utility Model Content

[0005] The purpose of this utility model is to provide a flue gas recirculation conveying duct for large thermal power plants, in order to solve the problem mentioned in the background art that, in the current market, the flue gas recirculation air nozzle is located at the bottom of the burner, and when the recirculation air velocity is too high, it is easy to interfere with the normal combustion of pulverized coal at the burner outlet, and in severe cases, it may cause poor ignition of pulverized coal in the lower layer of the burner or even the risk of fire extinguishing.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a large-scale thermal power plant flue gas recirculation conveying duct, including a first conveying duct, a connecting pipe connected to the left flange of the first conveying duct, an air inlet pipe connected to the rear end of the connecting pipe, and a second conveying duct connected to the rear flange of the air inlet pipe.

[0007] An installation ring is fitted between the connecting pipe and the first conveying air pipe. A support rod is connected to the inner wall of the installation ring. An installation plate is installed at the end of the support rod. A rotating rod is rotatably connected to the outside of the installation plate. A buffer fan blade and a cleaning scraper are installed on the outside of the rotating rod. A filter plate is installed at the left end of the support rod.

[0008] The lower end of the connecting pipe is connected to a collecting pipe, and the lower end of the collecting pipe is threaded with a sealing cap.

[0009] Preferably, the outer diameter of the mounting ring is larger than the inner diameter of the connection end between the first conveying air duct and the connecting pipe, and the mounting ring is pressed between the first conveying air duct and the connecting pipe.

[0010] Preferably, the rotating rod passes through the middle of the filter plate, and the rotating rod and the filter plate form a rotating structure.

[0011] Preferably, the buffer fan blades have an arc-shaped structure, and the buffer fan blades are evenly distributed on the outer side of the rotating rod. The buffer fan blades and the cleaning scraper are coaxially connected.

[0012] Preferably, the cleaning scraper and the filter plate are in close contact, and the end face of the cleaning scraper has a triangular structure.

[0013] Preferably, the position of the air inlet pipe corresponds to the position of the buffer fan blade, and the inner diameter of the air inlet pipe is smaller than the length of the buffer fan blade.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] (1) The flue gas recirculation conveying duct of this large thermal power plant can initially slow down the speed of the flue gas by using the obstruction of the buffer fan blades. The inner diameter of the right section of the first conveying duct gradually increases, so the speed of the flowing flue gas can be gradually slowed down again. Under the premise of ensuring sufficient recirculation air volume, the wind speed of the recirculation air is reduced, which reduces its interference with the ignition of pulverized coal at the burner outlet. It can effectively avoid the impact on the normal combustion of pulverized coal without affecting the boiler parameter adjustment, and prevent unit shutdown due to boiler flameout.

[0016] (2) The flue gas recirculation conveying duct of this large thermal power plant can buffer the speed of flue gas and intercept dust by using filter plates to prevent dust from being sprayed onto the burner and affecting combustion. At the same time, the rotation of the buffer fan blades drives the cleaning scraper to rotate, cleaning the filter plate and preventing it from clogging, ensuring the smooth flow of flue gas. Moreover, the filter plate and buffer fan blades can be disassembled for maintenance, improving its flexibility of use and thus improving the practicality of the flue gas recirculation conveying duct. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0018] Figure 2 This is a schematic diagram of the structure of this utility model from below;

[0019] Figure 3 This is a cross-sectional view of the connecting pipe of this utility model;

[0020] Figure 4 This is a schematic diagram of the buffer fan blade structure of this utility model;

[0021] Figure 5 This is a schematic diagram of the filter plate structure of this utility model;

[0022] Figure 6 This is a schematic diagram of the mounting ring structure of this utility model.

[0023] In the diagram: 1. First conveying air duct; 2. Connecting pipe; 3. Inlet air duct; 4. Second conveying air duct; 5. Mounting ring; 6. Support rod; 7. Mounting plate; 8. Rotating rod; 9. Buffer fan blade; 10. Cleaning scraper; 11. Collection pipe; 12. Sealing cover; 13. Filter plate. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figures 1-6 The present invention provides the following technical solution: a large-scale thermal power plant flue gas recirculation conveying duct, including a first conveying duct 1, a connecting pipe 2 connected to the left end flange of the first conveying duct 1, an air inlet pipe 3 connected to the rear end of the connecting pipe 2, and a second conveying duct 4 connected to the rear end flange of the air inlet pipe 3; an installation ring 5 is fitted between the connecting pipe 2 and the first conveying duct 1.

[0026] Furthermore, the outer diameter of the mounting ring 5 is larger than the inner diameter of the connection end of the first conveying air pipe 1 and the connecting pipe 2. The mounting ring 5 is pressed between the first conveying air pipe 1 and the connecting pipe 2. When assembling the first conveying air pipe 1 and the connecting pipe 2, the mounting ring 5 can be limited simultaneously to realize the assembly of the buffer fan blade 9 and the filter plate 13.

[0027] Furthermore, the position of the air inlet pipe 3 corresponds to the position of the buffer fan blade 9. The inner diameter of the air inlet pipe 3 is smaller than the length of the buffer fan blade 9, so that the flue gas comes into contact with the buffer fan blade 9 during the transport, slowing down its flow rate, and the flue gas drives the buffer fan blade 9 to rotate.

[0028] A support rod 6 is connected to the inner wall of the mounting ring 5. A mounting plate 7 is installed at the end of the support rod 6. A rotating rod 8 is rotatably connected to the outer side of the mounting plate 7.

[0029] Furthermore, the rotating rod 8 passes through the middle of the filter plate 13, and the rotating rod 8 and the filter plate 13 form a rotating structure, which allows the rotating rod 8 to rotate smoothly and avoids jamming between the two.

[0030] A buffer fan blade 9 and a cleaning scraper 10 are installed on the outer side of the rotating rod 8, and a filter plate 13 is installed on the left end of the support rod 6.

[0031] Furthermore, the buffer fan blade 9 has an arc-shaped structure, and the buffer fan blade 9 is evenly distributed on the outer side of the rotating rod 8. The buffer fan blade 9 and the cleaning scraper 10 are coaxially connected. The rotation of the buffer fan blade 9 can drive the cleaning scraper 10 to rotate synchronously.

[0032] Furthermore, the cleaning scraper 10 and the filter plate 13 are in close contact with each other, and the end face of the cleaning scraper 10 is a triangular structure, so that the cleaning scraper 10 can scrape and clean the filter plate 13 when rotating, thus preventing dust from adhering to the filter plate 13.

[0033] The lower end of the connecting pipe 2 is connected to the collecting pipe 11, and the lower end of the collecting pipe 11 is threadedly connected to the sealing cap 12;

[0034] Specifically, the right end of the first conveying duct 1 is connected to the nozzle located at the bottom of the burner, while the rear end of the second conveying duct 4 is connected to the outlet of the flue gas recirculation fan. The flue gas recirculation fan transports part of the flue gas extracted from the economizer into the second conveying duct 4. Then, the flue gas enters the inlet duct 3 and then the connecting pipe 2. After entering the connecting pipe 2, the flue gas first contacts the buffer fan blade 9, which initially slows down the speed of the flue gas. At the same time, the flue gas can push the buffer fan blade 9 to rotate through the rotating rod 8. The slowed flue gas flows to the right along the filter plate 13 into the first conveying duct 1. The inner diameter of the right section of the first conveying duct 1 gradually increases, which can make the flowing flue gas slow down again. The slowed flue gas is sent to the burner through the nozzle to assist in rapid combustion and avoid the flue gas injection speed being too fast, which would affect the ignition of the coal powder at the burner outlet.

[0035] During the flow of flue gas, the filter plate 13 can filter the dust and prevent it from being sprayed onto the burner through the nozzle and affecting combustion. When the buffer fan blade 9 rotates, the coaxially connected cleaning scraper 10 can be controlled to rotate. The cleaning scraper 10 scrapes and cleans the filter plate 13, sweeping off the dust adhering to the filter plate 13. The dust is concentrated in the collection pipe 11. Subsequently, the sealing cover 12 at the lower end of the threaded collection pipe 11 can be removed to clean the concentrated dust. The connecting pipe 2, which is connected to the flanges of the first conveying air pipe 1 and the second conveying air pipe 4, can be removed. The mounting ring 5 pressed between the connecting pipe 2 and the first conveying air pipe 1 can then be removed, thereby removing the filter plate 13 and the buffer fan blade 9 for maintenance. The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0036] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flue gas recirculation conveying duct for a large thermal power plant, comprising a first conveying duct (1), characterized in that: The left end flange of the first conveying air duct (1) is connected to a connecting pipe (2), the rear end of the connecting pipe (2) is connected to an air inlet pipe (3), and the rear end flange of the air inlet pipe (3) is connected to a second conveying air duct (4). An installation ring (5) is attached between the connecting pipe (2) and the first conveying air pipe (1). A support rod (6) is connected to the inner wall of the installation ring (5). An installation plate (7) is installed at the end of the support rod (6). A rotating rod (8) is rotatably connected to the outside of the installation plate (7). A buffer fan blade (9) and a cleaning scraper (10) are installed on the outside of the rotating rod (8). A filter plate (13) is installed at the left end of the support rod (6). The lower end of the connecting pipe (2) is connected to the collecting pipe (11), and the lower end of the collecting pipe (11) is threadedly connected to the sealing cap (12).

2. The flue gas recirculation conveying duct for a large thermal power plant according to claim 1, characterized in that: The outer diameter of the mounting ring (5) is larger than the inner diameter of the connection end of the first conveying air pipe (1) and the connecting pipe (2), and the mounting ring (5) is pressed between the first conveying air pipe (1) and the connecting pipe (2).

3. The flue gas recirculation conveying duct for a large thermal power plant according to claim 1, characterized in that: The rotating rod (8) passes through the middle of the filter plate (13), and the rotating rod (8) and the filter plate (13) form a rotating structure.

4. The flue gas recirculation conveying duct for a large thermal power plant according to claim 1, characterized in that: The buffer fan blade (9) has an arc-shaped structure. The buffer fan blade (9) is evenly distributed on the outer side of the rotating rod (8). The buffer fan blade (9) and the cleaning scraper (10) are coaxially connected.

5. The flue gas recirculation conveying duct for a large thermal power plant according to claim 1, characterized in that: The cleaning scraper (10) and the filter plate (13) are attached to each other, and the end face of the cleaning scraper (10) is a triangular structure.

6. The flue gas recirculation conveying duct for a large thermal power plant according to claim 1, characterized in that: The position of the air inlet pipe (3) corresponds to the position of the buffer fan blade (9), and the inner diameter of the air inlet pipe (3) is smaller than the length of the buffer fan blade (9).

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