Pulse self-ash-cleaning device and pulse self-ash-cleaning method for flue gas heat exchanger

Abstract

The invention relates to the technical field of heat exchanger self-cleaning, in particular to a pulse self-ash-cleaning device and a pulse self-ash-cleaning method.The pulse self-ash-cleaning device and the pulse self-ash-cleaning method for the flue gas heat exchanger comprise a ventilation pipeline, one end of the ventilation pipeline is an air inlet end, and the other end of the ventilation pipeline is an air outlet end; a first partition plate and a second partition plate are vertically and fixedly arranged between the middle of a ventilation pipeline body and the air outlet end in the air flow direction, and heat exchangers are arranged on the two side faces of the ventilation pipeline, the first partition plate and the second partition plate in a penetrating mode. Pulse adjustment is achieved through internal structure circulation adjustment and flue gas flow speed and flow direction control, circulation self-ash-cleaning is conducted on the heat exchanger, the structure is simple and reliable, the ash cleaning efficiency is high, and the problems that the heat exchange efficiency is reduced and the shutdown frequency is high due to ash deposition of the heat exchanger are effectively solved; the device can be used in various flue gas systems comprising shells and heat exchangers, such as coal-fired boilers in thermal power stations and incinerators in incineration plants.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger self-cleaning technology, specifically to a pulse self-cleaning device and method for flue gas heat exchangers. Background Technology

[0002] In flue gas treatment systems of industrial boilers, waste incinerators, and other equipment, heat exchangers are typically installed inside the flue to recover heat from the flue gas. However, flue gas contains a large amount of dust particles, which easily accumulate on the heat exchanger's surface as it flows through, forming ash buildup. Ash buildup significantly reduces the heat exchanger's efficiency, increases energy consumption, and in severe cases, can clog the casing, affecting the normal operation of the equipment.

[0003] Currently, the commonly used heat exchanger cleaning methods mainly include mechanical vibration cleaning, sonic cleaning, and pulse jet cleaning.

[0004] The existing technology still has the following drawbacks in its use: In existing technologies, mechanical rapping cleaning involves striking the heat exchanger with a rapping mechanism to dislodge the accumulated dust through vibration. However, this method can easily cause mechanical damage to the heat exchanger, and the cleaning is uneven, resulting in poor cleaning effect for fine dust.

[0005] Acoustic cleaning uses the vibration energy of sound waves to remove accumulated dust, but its cleaning strength is limited and it is not effective for thicker dust layers.

[0006] Pulse jet cleaning cleans the flue by blowing high-pressure gas into it to form a pulsed airflow. This method requires a complex high-pressure gas path system, which is costly. Furthermore, the blowing of high-pressure gas can easily interfere with the flue gas flow field and affect the normal transport of the flue gas.

[0007] Therefore, there is an urgent need for a heat exchanger cleaning technology that is simple in structure, low in cost, has good cleaning effect, and can be continuously cleaned, in order to solve the shortcomings of existing cleaning methods.

[0008] In view of this, we propose a pulse self-cleaning device and method for flue gas heat exchangers to solve the existing problems. Summary of the Invention

[0009] The purpose of this invention is to provide a pulse self-cleaning device and method for flue gas heat exchangers to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the first aspect of the present invention adopts the following technical solution: A flue gas heat exchanger pulse self-cleaning device includes a ventilation duct, one end of which is an air inlet and the other end is an air outlet. A first baffle and a second baffle are vertically fixed in the direction of airflow from the middle of the body of the ventilation duct to the air outlet. The first baffle and the second baffle separate the internal channel flow field of the ventilation duct. Heat exchangers are inserted through the two sides of the ventilation duct and the first and second baffles. The first partition and the second partition are equipped with a flow guiding mechanism that penetrates the upper and lower sidewalls of the ventilation duct at one end relative to the air inlet direction.

[0011] In a preferred embodiment, the heat exchanger includes a plurality of uniformly distributed heat exchange elements and a plurality of external pipes, wherein the heat exchange elements are thin tubes and perpendicular to the two sides of the ventilation pipes.

[0012] In a preferred embodiment, the ends of the heat exchanger are connected to the external pipe end-to-end by fasteners.

[0013] In a preferred embodiment, the end of the heat exchanger near the air outlet is the water inlet, and the end near the air inlet is the water outlet.

[0014] As a preferred embodiment, the ventilation duct has a channel direction of ° reference direction, and the first partition and the second partition divide the ventilation duct into a first flow channel, a second flow channel and a third flow channel in sequence.

[0015] In a preferred embodiment, the flow guiding mechanism includes a first driving component and a second driving component fixedly installed on the upper side wall of the ventilation duct, and a first flow guide plate and a second flow guide plate rotatably disposed between the upper and lower walls of the ventilation duct. The driving end of the first driving component passes through the upper side wall of the ventilation duct and is connected to the first flow guide plate, and the driving end of the second driving component passes through the upper side wall of the ventilation duct and is connected to the second flow guide plate.

[0016] As a preferred embodiment, both the air inlet and the air outlet have a fixing part, and the fixing part has multiple limiting holes.

[0017] The second aspect of the present invention adopts the following technical solution: A pulse self-cleaning method for a flue gas heat exchanger pulse self-cleaning device as described above includes the following steps: S1. By setting the first drive component and the second drive component to periodically and independently adjust the different working states of the first guide plate and the second guide plate, the self-cleaning of the circulating pulse flow is realized. First, in the initial working state, under normal ventilation state, the arrangement direction of the first guide plate and the second guide plate is consistent with the ventilation direction of the ventilation duct, i.e., the 0° reference direction. S2. Based on the state in step S1, within the time t1=1s, control the second driving component to drive the second guide plate to deflect to the right and contact the right side wall of the ventilation duct, and control the first driving component to drive the first guide plate to deflect to the right and contact the wall of the second guide plate, thereby blocking the air intake of the second flow channel and the third flow channel. At this time, the flue gas gathers in the first flow channel to flush the heat exchanger. When only the first flow channel is in the ventilation state, it is set to the first working state, and the first working state lasts for T1=20s. S3. Based on the state in step S2, within t2=1s, control the first drive component to drive the first guide plate to abut against the left side wall of the ventilation duct to block the air inlet of the first flow channel. The second drive component remains stationary in the state in step S2 to block the air inlet of the third flow channel. At this time, the flue gas gathers in the second flow channel to flush the heat exchanger. When only the second flow channel is in the ventilation state, it is set to the second station state, and the second station state lasts for T2=20s. S4. Based on the state in step S3, within the time t3=1s, the first drive component is controlled to remain stationary in the state in step S3 to block the air intake of the first flow channel. The second drive component drives the second guide plate to tilt to the left and contact the first guide plate to block the air intake of the second flow channel. At this time, the flue gas gathers into the third flow channel to flush the heat exchanger. When only the third flow channel is in the ventilation state, it is set to the third working state. The third working state is maintained for T3=20s. After the duration of T3=20s, within the time t4=1s, the arrangement direction of the first guide plate and the second guide plate is kept consistent with the ventilation direction of the ventilation duct, i.e., the 0° reference direction. The flue gas heat exchanger pulse self-cleaning device returns to the initial working state. S5. By setting a single cyclic pulse period T = 64s on the external controller, the ventilation pulse duration of each flow channel is the same, T1=T2=T3=20s, and the adjustment time t1=t2=t3=1s each time the flow guiding mechanism drives the switching station, where T=t1+t2+t3+t4+T1+T2+T3, the above steps are repeated to make the flue gas circulate in the forward direction to flush different parts of the heat exchanger in the first flow channel, the second flow channel, and the third flow channel, thereby realizing the cyclic pulse cleaning of the heat exchanger.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention only requires adjusting the first and second drive components to periodically and independently adjust the different working states of the first and second guide plates, so that the flue gas can be circulated and concentrated to scour different parts of the heat exchange components in the first, second, and third flow channels, thereby achieving pulse self-cleaning. This can effectively remove the ash accumulation on the surface of the heat exchanger, improve heat exchange efficiency, reduce manual labor, and the cleaning process will not cause equipment damage. The cleaning effect is significantly better than that of the existing technology, which improves the service life of the heat exchange equipment and reduces the frequency of downtime caused by malfunctions during operation.

[0019] This invention features a simple principle, strong adaptability, easy operation, simple structure, and low manufacturing and maintenance costs. It can be applied to various flue gas systems containing shells and heat exchangers, such as coal-fired boilers in thermal power plants, heating furnaces in chemical enterprises, and incinerators in waste incineration plants. It has a wide range of applications and can significantly improve enterprise efficiency. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a three-dimensional schematic diagram of the internal structure of the present invention; Figure 3 This is a schematic diagram of the air inlet end of the present invention; Figure 4 This is a schematic diagram of the width W of the ventilation duct and the width W0 of each sub-channel in the heat exchanger of the present invention; Figure 5 This is a schematic diagram comparing the influence of the length L of the first or second guide plate of the present invention on the flow field. Figure 6 This is a schematic diagram illustrating the effect of different numbers of baffles on the flow field according to the present invention; Figure 7 This is a schematic diagram of the working status of the first flow channel, the second flow channel, and the third flow channel when the number of partitions n=2 according to the present invention; Figure 8 This is a graph showing the variation of the heat transfer enhancement coefficient η with the duration T of the pulse flow; Figure 9 The graph shows the energy efficiency ratio and heat transfer enhancement coefficient for different pulse flow rates. Figure 10 This is a comparison diagram of the heat transfer characteristics of the present invention and the continuous ash accumulation in the tube bundle; Figure 11 A comparison of the actual cleaning effects of heat exchanger tube bundles with and without circulating pulse cleaning under experimental conditions. Figure 12 This is a comparison of the actual cleaning effects on the back side of the fourth row of heat exchanger tubes under experimental conditions with and without circulating pulse cleaning.

[0021] In the diagram: 1. Ventilation duct; 101. Air inlet; 102. Air outlet; 2. First baffle; 3. Second baffle; 4. Heat exchanger; 41. Heat exchange component; 42. External pipe; 5. Flow guiding mechanism; 51. First drive assembly; 52. Second drive assembly; 53. First guide plate; 54. Second guide plate; 6. Fastener; 7. First flow channel; 8. Second flow channel; 9. Third flow channel; 10. Fixing part; 11. Limiting hole; 12. Water inlet; 13. Water outlet. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0025] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0026] In addition, the term "multiple" should mean two or more.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments. Example

[0028] This embodiment provides a pulse self-cleaning device for a flue gas heat exchanger proposed in this invention, such as... Figures 1 to 12As shown, the system includes a ventilation duct 1, with one end being the air inlet 101 and the other end being the air outlet 102. In use, the actual width of the flue gas passage in the heat exchanger is set as W, which is typically several meters to over ten meters. Therefore, one or more sub-channels are considered to be set within the width W based on the actual width. The width of each sub-channel is W0 = W / N, where N is the number of sub-channels, and the sub-channels are separated by fixed baffles. Under experimental conditions, the number of baffles in each sub-channel is determined to be n. According to actual experimental tests, when the flue gas pulse velocity reaches 14 m / s or higher, it has good dust removal and energy-saving effects. Therefore, the number of baffles is n = 14 / u, rounded to the nearest integer, where u is the flue gas velocity. For example, if the flue gas velocity u = 6 m / s, then n = 14 / u = 2.33. Therefore, taking n = 2 is a more reasonable approach.

[0029] like Figures 1 to 7 The figure shows the effect of different numbers of baffles on the flow field. It can be seen that when u = 6 m / s, the maximum flow velocity in the channel exceeds 14 m / s after adding baffles. Further statistical analysis of the delayed average velocity in the channel reveals that the average velocity is 12.21 m / s when n = 1, 18.47 m / s when n = 2, and 24.03 m / s when n = 3. Therefore, when n = 2, the requirement of a flue gas pulse velocity exceeding 14 m / s is met. like Figures 5 to 6 As shown, when the flue gas inflow velocity u=6m / s, L / W0=1.00, and the number of baffles n=2, the flow field distribution under different adjustment states is as follows: Calculations show that the average flue gas velocity in the flow channel under the three different working states is approximately 18m / s, which meets the dust removal requirements. When n=1, the average flue gas velocity in the first and second working states is 12.5m / s, which does not meet the dust removal requirements. When there are no baffles, an effective pulse flow cannot be formed in a single channel for dust removal.

[0030] like Figures 1 to 3 , Figures 5 to 12As shown, a first baffle 2 and a second baffle 3 are vertically fixed along the airflow direction from the middle of the body of the ventilation duct 1 to the air outlet 102. The first baffle 2 and the second baffle 3 separate the internal flow field of the ventilation duct 1. Heat exchangers 4 are inserted through the two sides of the ventilation duct 1 and the first baffle 2 and the second baffle 3. After experimental analysis, when the first baffle 2 and the second baffle 3 are set, the ventilation duct is divided into 3 channels. At this time, the hot smoke airflow entering the ventilation duct 1 flows from the air inlet 101 to the air outlet 102. During this period, the hot smoke airflow is guided to different channels separated by the first baffle 2 and the second baffle 3 according to different guiding states. The flow field, by reducing the cross-sectional area of ​​the flow field, increases the flow velocity of hot gas in the flow path, thereby increasing the impact force. This achieves heat exchange with the heat exchanger 4 while simultaneously enabling a circulating pulse self-cleaning effect on the dust accumulated on the heat exchanger 4. This allows the flue gas to circulate and concentrate to positively flush different parts of the heat exchange components in the first, second, and third flow channels, thus achieving pulse self-cleaning. This effectively removes dust accumulation on the surface of the heat exchanger, improves heat exchange efficiency, reduces manual labor, and the cleaning process does not cause equipment damage. The cleaning effect is significantly better than that of existing technologies, increasing the service life of the heat exchange equipment and reducing the frequency of downtime caused by operational failures.

[0031] like Figures 1 to 3 As shown, further, the first partition 2 and the second partition 3 are equipped with a flow guiding mechanism 5 that penetrates the upper and lower side walls of the ventilation duct 1 at one end relative to the air inlet 101. In use, the flow guiding mechanism 5 is set to adjust the first flow guiding plate 53 and the second flow guiding plate 54, thereby guiding the hot air entering the air inlet 101 to achieve the effect of circulating pulse.

[0032] like Figures 1 to 3 As shown, in a preferred embodiment, the heat exchanger 4 includes multiple uniformly distributed heat exchange elements 41 and multiple external pipes 42. The heat exchange elements 41 are thin tubes and perpendicular to the two sides of the ventilation duct 1. In use, by setting multiple heat exchange elements 41, the heat in the hot flue gas can be exchanged and carried away by the fluid in the pipe. At the same time, the temperature in the hot flue gas is reduced, and the dust in the hot flue gas also adheres to the heat exchange elements 41, providing the basic conditions for circulating pulse cleaning.

[0033] like Figures 1 to 2 As shown, in a preferred embodiment, the ends of the heat exchanger 41 are connected to the outer pipe 42 end to end by fasteners 6; in use, the two heat exchangers 41 are connected by fasteners 6 and outer pipe 42, so that the heat exchangers can be easily replaced in time when damaged, thus improving maintenance efficiency.

[0034] like Figures 1 to 2 , Figure 7As shown, in a preferred embodiment, the end of the heat exchanger 41 near the air outlet 102 is the water inlet 12, and the end near the air inlet 101 is the water outlet 13. In use, since the temperature of the hot flue gas at the air inlet 101 is relatively high and the temperature at the air outlet 102 is relatively low, it is more reasonable to set the end of the heat exchanger 41 near the air outlet 102 as the water inlet 12, which also makes the heat exchange effect of the water in the heat exchanger 41 better and the temperature more uniform after flowing through the ventilation duct.

[0035] like Figures 1 to 3 , Figure 7 As shown, in a preferred embodiment, the channel direction of the ventilation duct 1 is the 0° reference direction. The first partition 2 and the second partition 3 divide the ventilation duct 1 into the first flow channel 7, the second flow channel 8, and the third flow channel 9 in sequence. In use, the hot smoke airflow in the ventilation duct 1 is sequentially circulated into the first flow channel 7, the second flow channel 8, and the third flow channel 9 to achieve a circulating pulse effect.

[0036] like Figures 1 to 3 , Figure 5 As shown, in a preferred embodiment, the flow guiding mechanism 5 includes a first drive assembly 51 and a second drive assembly 52 fixedly installed on the upper side wall of the ventilation duct 1, and a first guide plate 53 and a second guide plate 54 rotatably disposed between the upper and lower walls of the ventilation duct 1. The drive end of the first drive assembly 51 is connected to the first guide plate 53, and the drive end of the second drive assembly 52 is connected to the second guide plate 54. In use, the first drive assembly 51 controls the position of the first guide plate 53, and the second drive assembly 52 controls the position of the second guide plate 54. The maximum length Lmax of the first guide plate 53 and the second guide plate 54 is 2500mm. When the ratio of the length L of the flow guiding baffle to the width W0 of the channel is not less than 0.75, that is, L / W0≥0.75, the velocity distribution in the flue gas channel is relatively uniform, and the flow dead zone is suppressed. Therefore, the value of L / W0 is preferably between 0.75 and 1.00. like Figures 1 to 5As shown, during the implementation of the scheme, it is necessary to optimize the lengths of the first guide plate 53 and the second guide plate 54. Based on this, the number N of sub-channels in the heat exchanger is determined. Since the maximum length of the baffle Lmax = 2500mm, N = W / Lmax, and the result is rounded up. The actual width W0 of each sub-channel = W / N. Since the value of L / W0 is between 0.75 and 1.00, the actual length L of the baffle can be determined. For example, if the total width W of the flue is 7000mm, the number of sub-channels N = W / Lmax = 7000 / 2500 = 2.8, rounded up, i.e., N = 3. Therefore, the actual width W0 of each sub-channel = W / N = 7000 / 3 = 2333mm. Since the value of L / W0 is between 0.75 and 1.00, the actual length L of the baffle = [0.75*2333mm, 1.0*2333mm] = [1750mm, 2333mm].

[0037] like Figure 1 As shown, in a preferred embodiment, both the air inlet 101 and the air outlet 102 have a fixing part 10 at their ports. The fixing part 10 has multiple limiting holes 11. In practice, by opening multiple limiting holes 11 on the fixing part 10, the ventilation duct 1 can be fixedly installed, which can be integrated and applied on a large scale.

[0038] The pulse self-cleaning method of the above-mentioned flue gas heat exchanger pulse self-cleaning device includes the following steps: like Figure 3 As shown, step S1 involves adjusting the initial state settings of the device. By setting the first drive component 51 and the second drive component 52 to periodically and independently adjust the different working states of the first guide plate 53 and the second guide plate 54, the self-cleaning of the circulating pulse flow is realized. First, in the initial working state, under normal ventilation state, the arrangement direction of the first guide plate 53 and the second guide plate 54 is consistent with the ventilation direction of the ventilation duct 1, i.e., the 0° reference direction. During implementation, the state of the flue gas heat exchanger pulse self-cleaning device is initialized to prepare for the circulating pulse state.

[0039] like Figure 7 As shown, the adjustment of S2 and the first station status. Based on the state of step S1, within the time t1=1s, the second driving component 52 is controlled to drive the second guide plate 54 to deflect to the right and contact the right side wall of the ventilation duct 1, and the first driving component 51 is controlled to drive the first guide plate 53 to deflect to the right and contact the wall of the second guide plate 54, thereby blocking the air intake of the second flow channel 8 and the third flow channel 9. At this time, the flue gas gathers in the first flow channel 7 to flush the heat exchanger 41. When only the first flow channel 7 is in the ventilation state, it is set to the first working state, and the first working state lasts for T1=20s. During implementation, the hot flue gas flow inside the pulse self-cleaning device of the flue gas heat exchanger is regulated to flow into the first flow channel 7, thereby reducing the flow cross-sectional area, increasing the flow speed of the hot flue gas flow, and thus improving the impact force of the pulse, significantly improving the pulse cleaning effect.

[0040] like Figure 7 As shown, the adjustment of S3 and the second station status. Based on the state in step S2, within the time t2=1s, the first drive component 51 drives the first guide plate 53 to abut against the left side wall of the ventilation duct 1 to block the air intake of the first flow channel 7. The second drive component 52 remains stationary in the state in step S2 to block the air intake of the third flow channel 9. At this time, the flue gas gathers in the second flow channel 8 to scour the heat exchanger 41. When only the second flow channel 8 is in the ventilation state, it is set to the second working state, and the second working state lasts for T2=20s. During implementation, the hot flue gas flow inside the pulse self-cleaning device of the flue gas heat exchanger is regulated to flow into the second flow channel 8, thereby reducing the flow cross-sectional area, increasing the flow speed of the hot flue gas flow, and thus improving the impact force of the pulse, which significantly improves the pulse cleaning effect.

[0041] like Figure 7 As shown, the adjustment of S4 and the third station status. Based on the state in step S3, within the time interval t3=1s, the first drive component 51 is kept stationary in the state in step S3, thus blocking the air intake of the first flow channel 7. The second drive component 52 drives the second guide plate 54 to tilt to the left and abut against the first guide plate 53, thus blocking the air intake of the second flow channel 8. At this time, the flue gas gathers in the third flow channel 9 and scours the heat exchanger 41. When only the third flow channel 9 is in the ventilation state, it is set to the third station state, and the third station state is maintained for T3=20s. After 20 seconds, within t4 = 1 second, the arrangement direction of the first guide plate 53 and the second guide plate 54 is made consistent with the ventilation direction of the ventilation duct 1, i.e., the 0° reference direction. The flue gas heat exchanger pulse self-cleaning device returns to its initial working state. During implementation, the hot flue gas flow inside the flue gas heat exchanger pulse self-cleaning device is regulated to flow into the third flow channel 9, thereby reducing the flow cross-sectional area, increasing the flow velocity of the hot flue gas flow, and thus enhancing the impact force of the pulse, significantly improving the pulse cleaning effect.

[0042] S5. Periodic cycling of different workstation states and reset of the initial workstation state. By setting a single cyclic pulse period T = 64s on the external controller, the ventilation pulse duration for each flow channel is the same, T1 = T2 = T3 = 20s, and the adjustment duration t1 = t2 = t3 = 1s each time the flow guiding mechanism 5 drives to switch positions, where T = t1 + t2 + t3 + t4 + T1 + T2 + T3, and repeating the above steps, the flue gas is circulated in the forward direction to flush different parts of the heat exchanger 41 in the first flow channel 7, the second flow channel 8, and the third flow channel 9, thereby achieving cyclic pulse cleaning of the heat exchanger. During implementation, the flue gas heat exchanger pulse self-cleaning device is restored to the initial state to prepare for the next pulse, thus achieving a continuous pulse cleaning effect.

[0043] Experimental verification analysis and specific implementation results: To verify the feasibility and practical effectiveness of this invention, the inventors conducted experimental tests on pulsed flow sweeping across heat exchanger tube bundles using a self-built ash accumulation experimental platform. The flow channel cross-section for this test was a rectangle with a height of 100 mm and a width of 120 mm. The heat exchanger used round tubes with a diameter of 20 mm, arranged in six rows and three columns, with a transverse tube spacing of 50 mm and a longitudinal spacing of 30 mm. The time-averaged Nusselt number (Nu) and the heat transfer enhancement coefficient (η) were used as quantitative indicators of the heat exchanger's convective heat transfer capacity to visually describe the actual effect of pulsed ash removal.

[0044] like Figure 8 The graph shows the variation of the heat transfer enhancement coefficient η with the duration T of the pulse flow. As can be seen from the graph, when the pulse flow velocity is 10 m / s, 12 m / s, and 14 m / s, the heat transfer enhancement coefficient is highest at a duration of 20 s. The η at 30 s shows a slight decrease compared to 20 s, indicating that the loose ash on the surface of the ash layer is basically removed after approximately 20 s of pulse flow purging of the tube bundle. When the pulse flow velocity is 16 m / s, the η values ​​for different durations are similar. This is because the pulse flow velocity is the dominant influencing factor in this invention; as the pulse velocity increases, the duration has little effect on the pulse cleaning effect. In conclusion, a pulse flow duration T of 20 s is recommended to effectively improve the heat exchange capacity of the tube bundle.

[0045] like Figure 9 As shown, the energy efficiency ratio and heat transfer enhancement coefficient are different for different pulse flow velocities when the duration is 20s. It can be seen that the heat transfer enhanced by the 10m / s pulse flow is much greater than the energy consumed, but the heat transfer enhancement coefficient is low, resulting in poor dust removal performance under this condition. Considering both indicators, when the pulse velocity is 14m / s and the peak duration is 20s, the energy efficiency ratio is 4.41 and the heat transfer enhancement coefficient is 7.59%, demonstrating better energy economy and energy efficiency while maintaining a good enhanced heat transfer effect. In conclusion, pulse flow velocities above 14m / s have good dust removal and energy-saving effects.

[0046] A cyclic experiment of pulse cleaning was conducted under the condition of a pulse flow rate of 14 m / s and a duration of 20 s, and compared with a control group that did not perform pulse cleaning. Figure 10 It can be seen that the heat exchange capacity of the heat exchanger is increased by 8%-11% after each pulse, and the average heat exchange capacity of the heat exchanger is still significantly increased by about 7.8% after multiple pulses. Figures 11 to 12 The image shows a comparison of heat exchanger tube bundles with pulse cleaning and without cleaning. It can be seen that after the heat exchanger undergoes cyclic pulse cleaning, most of the loose ash is completely blown off, the ash coverage is greatly reduced, and the ash thickness in the heat exchange area of ​​the fourth row of tube bundles is reduced, indicating that the present invention has good flue gas self-cleaning and cyclic cleaning performance.

[0047] The above specific embodiments are merely several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A pulse self-cleaning device for a flue gas heat exchanger, comprising a ventilation duct (1), characterized in that: One end of the ventilation duct (1) is the air inlet (101) and the other end is the air outlet (102). A first partition (2) and a second partition (3) are vertically fixed in the airflow direction between the middle of the body of the ventilation duct (1) and the air outlet (102). The first partition (2) and the second partition (3) separate the internal channel flow field of the ventilation duct (1). Heat exchangers (4) are inserted through the two sides of the ventilation duct (1) and the first partition (2) and the second partition (3). The first partition (2) and the second partition (3) are equipped with a flow guiding mechanism (5) that penetrates the upper and lower side walls of the ventilation duct (1) at one end relative to the air inlet end (101).

2. The pulse self-cleaning device for a flue gas heat exchanger according to claim 1, characterized in that: The heat exchanger (4) includes multiple uniformly distributed heat exchange elements (41) and multiple external pipes (42). The heat exchange elements (41) are thin tubes and perpendicular to the two sides of the ventilation pipe (1).

3. The pulse self-cleaning device for a flue gas heat exchanger according to claim 2, characterized in that: The end of the heat exchanger (41) is connected to the outer pipe (42) end to end by fasteners (6).

4. The pulse self-cleaning device for a flue gas heat exchanger according to claim 2, characterized in that: The heat exchanger (41) has a water inlet (12) at the port near the air outlet (102) and a water outlet (13) at the end near the air inlet (101).

5. The pulse self-cleaning device for a flue gas heat exchanger according to claim 1, characterized in that: The ventilation duct (1) has a channel direction of 0° reference direction. The first partition (2) and the second partition (3) divide the ventilation duct (1) into a first flow channel (7), a second flow channel (8), and a third flow channel (9) in sequence.

6. The pulse self-cleaning device for a flue gas heat exchanger according to claim 1, characterized in that: The flow guiding mechanism (5) includes a first drive assembly (51) and a second drive assembly (52) fixedly installed on the upper side wall of the ventilation duct (1), a first guide plate (53) and a second guide plate (54) rotatably disposed between the upper and lower walls of the ventilation duct (1). The drive end of the first drive assembly (51) passes through the upper side wall of the ventilation duct (1) and is connected to the first guide plate (53). The drive end of the second drive assembly (52) passes through the upper side wall of the ventilation duct (1) and is connected to the second guide plate (54).

7. The pulse self-cleaning device for a flue gas heat exchanger according to claim 1, characterized in that: Both the air inlet (101) and the air outlet (102) have a fixing part (10) at their ports, and the fixing part (10) has multiple limiting holes (11).

8. A pulse self-cleaning method for a flue gas heat exchanger pulse self-cleaning device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. By setting the first drive component (51) and the second drive component (52) to periodically and independently adjust the different working states of the first guide plate (53) and the second guide plate (54), the self-cleaning of the circulating pulse flow is realized. First, in the initial working state, the arrangement direction of the first guide plate (53) and the second guide plate (54) in the normal ventilation state is consistent with the ventilation direction of the ventilation duct (1), that is, the 0° reference direction. S2. Based on the state of step S1, within the time t1=1s, control the second drive component (52) to drive the second guide plate (54) to deflect to the right and contact the right side wall of the ventilation duct (1), and control the first drive component (51) to drive the first guide plate (53) to deflect to the right and contact the wall of the second guide plate (54), thereby blocking the air intake of the second flow channel (8) and the third flow channel (9). At this time, the flue gas gathers in the first flow channel (7) to flush the heat exchanger (41). When only the first flow channel (7) is in the ventilation state, it is set to the first working state, and the first working state lasts for T1=20s. S3. Based on the state in step S2, within t2=1s, control the first drive component (51) to drive the first guide plate (53) to abut against the left side wall of the ventilation duct (1) to block the air intake of the first flow channel (7). The second drive component (52) remains unchanged in the state in step S2 to block the air intake of the third flow channel (9). At this time, the flue gas gathers in the second flow channel (8) to flush the heat exchanger (41). When the second flow channel (8) is in the ventilation state, it is set to the second working state, so that the second working state lasts for T2=20s. S4. Based on the state in step S3, within t3=1s, control the first drive component (51) to remain in the state in step S3, thereby blocking the air intake of the first flow channel (7). The second drive component (52) drives the second guide plate (54) to tilt to the left and collide with the first guide plate (53), thereby blocking the air intake of the second flow channel (8). At this time, the flue gas gathers into the third flow channel (9) to flush the heat exchanger (41). When the third flow channel (9) is in the ventilation state, it is set to the third working state, and the third working state lasts for T3=20s. After T3=20s, within t4=1s, make the arrangement direction of the first guide plate (53) and the second guide plate (54) consistent with the ventilation direction of the ventilation duct (1), i.e., the 0° reference direction. The flue gas heat exchanger pulse self-cleaning device returns to the initial working state. S5. By setting a single cyclic pulse period T = 64s on the external controller, the ventilation pulse duration of each flow channel is the same, T1 = T2 = T3 = 20s, and the adjustment duration t1 = t2 = t3 = 1s when the flow guiding mechanism (5) drives the switching station each time, where T = t1 + t2 + t3 + t4 + T1 + T2 + T3, repeat the above steps to make the flue gas circulate and flush different parts of the heat exchanger (41) in the first flow channel (7), the second flow channel (8), and the third flow channel (9) in the forward direction, so as to realize the cyclic pulse cleaning of the heat exchanger.

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