Anti-ash-deposition heat exchange system and method capable of adjusting flue gas through-flow section

Abstract

The invention provides an ash deposition prevention heat exchange system and method capable of adjusting a flue gas through-flow section, belongs to the technical field of flue gas treatment of coal-fired units, and can at least partially solve the problems that an existing baffle door is complex in structure, prone to jamming and air leakage, high in maintenance cost and prone to causing uneven airflow and local ash deposition; a traditional soot blower is high in energy consumption and limited in effect, and possibly causes tube bundle abrasion. In order to solve the problems that a heat exchanger with a fixed section cannot dynamically adjust the through-flow section and the flow velocity is insufficient during low load, the heat exchanger comprises a flue, the flue is provided with a section air bag assembly, a heat exchange assembly, an air path control module and a DCS control module, and by arranging the section air bag assembly capable of controlling expansion in the flue and combining a partition heat exchange structure and DCS closed-loop control, the heat exchange efficiency is improved, and the heat exchange efficiency is improved. Dynamic adjustment of the flue gas through-flow section is achieved, the flue gas flow speed under the low-load working condition is effectively increased, fly ash deposition is restrained, and ash deposition and performance degradation of a heat exchange assembly are slowed down.

Description

Technical Field

[0001] This invention belongs to the field of flue gas treatment technology for coal-fired power units, and specifically relates to a flue gas flow cross-section adjustment system and method for preventing ash accumulation heat exchange. Background Technology

[0002] With the rapid development of new energy power generation such as wind power and photovoltaics, the power system's requirements for the flexibility of traditional coal-fired power units are increasing. Coal-fired power units need to operate under peak-shaving conditions within a wide load range (30%-100% rated load) to maintain grid stability. This leads to an increased proportion of low-load operating time, making flue gas treatment a key challenge, especially in the flue gas heat exchange stage. Optimization of flow and heat exchange is needed to improve efficiency and reduce environmental impact. Under low-load conditions, boiler exhaust volume decreases, and the flue gas velocity in the flue is often below 6 m / s, far below the critical velocity for fly ash transport (8 m / s). This makes fly ash in the flue gas easily accumulate on the inner wall of the flue, elbows, and the surface of heat exchanger tube bundles such as low-temperature economizers, forming an ash layer. This leads to increased resistance, decreased heat exchange efficiency, low-temperature corrosion, and potential blockage, affecting the economy and reliability of coal-fired power units.

[0003] However, existing solutions, including flue gas duct zoning and damper adjustment, suffer from complex damper structures, susceptibility to jamming and air leakage, high maintenance costs, and a tendency to cause uneven airflow and localized ash accumulation. Traditional soot blowing devices (such as steam or sonic soot blowing) are energy-intensive, have limited effectiveness, and may cause tube bundle wear. While fixed-section heat exchanger optimization can adjust tube bundle density, it cannot dynamically adjust the flow cross-section, and insufficient flow velocity remains a problem at low loads. These methods are all difficult to accurately match wide-load requirements and lack the flexibility to integrate ash accumulation prevention and stable heat exchange. Therefore, we propose an ash accumulation prevention heat exchange system and method based on flue gas flow cross-section adjustment. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a flue gas flow cross section adjustment anti-ash accumulation heat exchange system and method.

[0005] One aspect of the present invention provides a flue gas flow cross-section adjustment anti-ash accumulation heat exchange system, including a flue, wherein the flue is provided with: The cross-section airbag assembly includes an airbag disposed on the inner wall of the flue and a sensing unit disposed on the side of the airbag facing the heat exchange assembly. The heat exchange assembly is disposed in the flue downstream of the cross-section airbag assembly. The heat exchange assembly includes multiple heat exchange zones, and each heat exchange zone is provided with a sensing unit corresponding to the sensing unit. The airway control module includes an inflation unit connected to the airbag tubing; and The DCS control module is electrically connected to the sensing unit and the pneumatic control module respectively; The heat exchange partition consists of partition plates and tube bundle partition plates within the heat exchange assembly. The sensing unit is disposed on the partition plate, and the DCS control module controls the start and stop of the inflation unit based on the signals from the sensing unit.

[0006] Furthermore, the airbag includes an airbag body disposed on the inner wall of the flue and a protective layer disposed on the outer side of the airbag body.

[0007] Furthermore, the sensing unit is a capacitive sensor, and the distance between the sensing unit and each of the sensing units ranges from 1 to 5 mm.

[0008] Specifically, the air circuit control module also includes a filter and a dehumidifier arranged sequentially on the pipeline between the inflation unit and the airbag.

[0009] Specifically, the partition is a U-shaped partition, and each heat exchange zone includes at least a first zone, a second zone, a third zone, a fourth zone, and a fifth zone arranged sequentially along the inner wall of the flue towards the central area of ​​the flue.

[0010] Preferably, the partition is a stainless steel partition, and the partition is integrally formed with the heat exchanger of the heat exchange assembly.

[0011] Specifically, the length of the cross-sectional airbag assembly ranges from 1.5 to 3 m, and the initial thickness of the airbag ranges from 50 to 100 mm.

[0012] Furthermore, the cross-sectional airbag assembly is connected to the inner wall of the flue via a connector, and a sealing gasket is provided at the connection position between the cross-sectional airbag assembly and the flue.

[0013] Furthermore, the air circuit control module also includes a flow regulating valve and a check valve. The flow regulating valve is installed on the pipeline between the dehumidifier and the air bag, and the check valve is installed on the pipeline between the inflation unit and the filter. The flow regulating valve is electrically connected to the DCS control module, and a sealing strip is provided at the connection between the pipeline and the air bag.

[0014] Another aspect of the present invention provides a method for preventing ash accumulation heat exchange by adjusting the flue gas flow cross section. The method is implemented using the above-mentioned flue gas flow cross section adjustment system for preventing ash accumulation, and includes the following steps: S1: The DCS control module collects the pressure sensing unit signal of the gas path control module and the inlet and outlet flue gas temperature and pressure difference operating parameters of the heat exchange component in real time, and determines the target positioning position according to the load demand of the coal-fired unit. S2: The inflation unit is activated, and the filtered and dehumidified gas is introduced into the cross-sectional airbag assembly, and the airbag begins to inflate. S3: During the expansion process, the sensing unit passes through each of the sensing units in sequence. The DCS control module assigns a logical number to the partition position corresponding to each sensing unit according to the triggering order of each sensing unit, and drives the airbag to stop at different partition positions according to the target load command. S4: The pressure sensing unit monitors the pressure inside the airbag in real time and feeds it back to the DCS control module. The DCS control module adjusts the inflation volume to maintain the pressure stable within a preset range. If the pressure drop rate exceeds a set threshold, the DCS control module issues a leak alarm. If the airbag needs to be switched to another positioning position, the DCS control module controls the airbag to deflate and then repeats steps S2 to S3.

[0015] The beneficial effects of this invention are as follows: By installing controllable expansion cross-sectional airbag components within the flue, combined with a zoned heat exchange structure and DCS closed-loop control, dynamic adjustment of the flue gas flow cross-section is achieved. This effectively increases the flue gas velocity under low-load conditions, suppresses fly ash deposition, and slows down ash accumulation and performance degradation of the heat exchange components. Compared to traditional damper gates and soot blowing methods, this invention features a simple structure, flexible adjustment, low energy consumption, and high reliability, meeting the flexible peak-shaving operation requirements of coal-fired units across a wide load range. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-sectional airbag assembly structure of a flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to a specific embodiment of the present invention. Figure 3 This is a schematic diagram of the installation of a cross-sectional airbag assembly for an anti-ash accumulation heat exchange system with adjustable flue gas flow cross-section, according to a specific embodiment of the present invention. Figure 4 This is a schematic diagram of the partitioned layout of the heat exchange components of a flue gas flow cross section adjustment anti-ash accumulation heat exchange system according to a specific embodiment of the present invention. Figure 5 This is a flowchart illustrating the steps of a flue gas flow cross-section adjustment method for preventing ash accumulation and heat exchange, according to a specific embodiment of the present invention.

[0017] One of them is a flue; 2. Section airbag assembly, 21. Airbag body, 22. Protective layer, 23. Sealing gasket, 24. Capacitive sensor; 3 Heat exchange components, 31 partition plate, 32 tube bundle partition plate, 33 heat exchange zones, 33a first zone, 33b second zone, 33c third zone, 33d fourth zone, 33e fifth zone, 34 heat exchange tube bundle, 35 sensing unit; 4. Gas circuit control module, 41. Inflation unit, 42. Check valve, 43. Filter, 44. Dehumidifier, 45. Flow regulating valve, 46. Pressure sensing unit, 47. Connecting pipeline; 5 DCS control module, 51 controller, 52 audible and visual alarm, 53 display terminal; 6. Connector; 7. Smoke temperature sensor; 8. Differential pressure sensor. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 , Figure 2 , Figure 4 As shown in the figure, a flue gas flow cross-section adjustment anti-ash accumulation heat exchange system provided by a specific embodiment of the present invention includes a flue 1, on which: The cross-section airbag assembly 2 includes an airbag disposed on the inner wall of the flue 1 and a sensing unit disposed on the side of the airbag facing the heat exchange assembly; the heat exchange assembly 3 is disposed in the downstream flue 1 of the cross-section airbag assembly, and the heat exchange assembly 3 includes multiple heat exchange zones 33, each heat exchange zone 33 being provided with a sensing unit 35 corresponding to the sensing unit; the air path control module 4 includes an inflation unit 41 connected to the airbag pipeline and a pressure sensing unit 46 disposed inside the airbag; and the DCS control module 5 is electrically connected to the sensing unit and the air path control module 4, respectively; wherein, the heat exchange zone 33 is composed of a partition plate 31 and a tube bundle partition plate 32 in the heat exchange assembly 3, the sensing unit 35 is disposed on the partition plate 31, and the DCS control module 5 controls the start and stop of the inflation unit 41 according to the signals of the sensing unit and the sensing unit 35.

[0020] Specifically, the airbag in the cross-section airbag assembly 2 adopts a flat circular or square structure to adapt to flues with different cross-sectional shapes. Its diameter or side length precisely matches the inner wall of the flue, with a gap ≤5mm, ensuring that the airbag tightly fits the inner wall of the flue when inflated, eliminating any airflow leakage channels. It covers the heat exchanger inlet flue or flue bends, areas prone to ash accumulation. The initial pressure is zero, corresponding to an initial thickness range of 50–100mm for the flat circular ring. The inflated side of the airbag has a built-in mounting groove for embedding a sensing unit. After encapsulation, the mounting groove and sensing unit are flush with the outer protective layer to avoid airflow disturbance or fly ash scouring. The position of the sensing unit must ensure that it aligns sequentially with the sensing units of each partition plate when the airbag inflates. The airbag body 21 uses fluororubber or silicone rubber as a substrate, possessing good elasticity, high temperature resistance, aging resistance, and flue gas corrosion resistance. The protective layer is a PTFE coating or a ceramic wear-resistant coating. The PTFE coating possesses excellent corrosion resistance and non-stick properties, while the ceramic coating exhibits high strength and wear resistance, effectively resisting fly ash erosion and flue gas corrosion, extending the airbag's service life to over 3 years. The sensing unit is a capacitive sensor 24, employing a high-temperature resistant capacitive proximity sensor with a temperature tolerance range consistent with the airbag body 21, a protection rating ≥ IP67, and stable sensing sensitivity. The cross-sectional airbag assembly 2 adopts a modular design, detachably connecting to the inner wall of the flue 1 via connector 6. The connection point is equipped with a high-temperature resistant sealing gasket to ensure sealing performance. The wires of the capacitive sensor 24 are made of high-temperature resistant shielded wire, built into the wiring groove of the airbag body 21, and the connection end with the DCS control module 5 uses an explosion-proof sealed joint for effective sealing protection. The modular structure supports partial repair (such as coating damage repair or sensor replacement) or overall replacement, simplifying maintenance operations, reducing time consumption, and lowering maintenance costs.

[0021] Furthermore, such as Figure 3 As shown, heat exchange component 3 is precisely matched with cross-section airbag component 2, achieving stable heat exchange over a wide load range through typical load zoning design: Zoning Design: Abandoning the traditional baffle door zoning method, the heat exchanger body is designed with multiple independent typical load heat exchange zones radially from the inside to the outside through the 31 partitions 31 and tube bundle partitions 32 arranged in a U-shape. The flow area of ​​each zone is precisely designed according to the typical load range of the coal-fired unit, corresponding one-to-one with the different expansion depths of the airbag (the minimum expansion amount of the airbag matches the full load zone, and the maximum expansion amount matches the low load zone). The partitions are equipped with metal conductive sensing units, which are arranged in the order of "full load → low load" at intervals, and the spacing matches the depth gradient of the airbag expansion (e.g., the spacing between adjacent sensing units is 50-80mm). This ensures that when the airbag expands, a single capacitive sensor can generate sensing signals with each sensing unit in sequence, corresponding to the positioning logic of "position one (full load), position two (medium-high load)...".

[0022] Structural features: The heat exchange tube bundles in each heat exchange zone have a uniform arrangement density (100-150 tubes / m²), ensuring uniform heat exchange efficiency under different loads and eliminating local heat exchange dead zones; the partition plate 31 and the tube bundle partition plate 32 are made of high-temperature and corrosion-resistant steel such as 316L stainless steel or ND steel, integrally formed with the heat exchanger body, resulting in a stable structure with no additional flow resistance loss, and a service life consistent with the heat exchanger body; the sensing unit has no coating on its surface, exposing it for conductivity, ensuring the sensing sensitivity of the capacitive sensor; the heat exchanger body includes the heat exchange tube bundle 34.

[0023] Furthermore, the air circuit control module 4 provides a stable and clean air source for the cross-section airbag assembly 2, ensuring reliable regulation. Its components include an inflation unit 41, a filter 43, a dehumidifier 44, a flow regulating valve 45, a check valve 42, a pressure sensor 46, and connecting pipes 47. The inflation unit 41 is an inflation pump, characterized by rapid start / stop response and stable output pressure, replacing traditional blowers. The inflation pump provides inflation power, with an outlet pressure of 0.4–0.8 MPa and a flow rate of 3–10 m³ / min, meeting the inflation requirements of airbags of different sizes. The filter 43 has a filtration accuracy of ≤1 μm, effectively removing airborne dust particles and preventing contamination of the airbag. Scale buildup; the dew point of the outlet gas from the dehumidifier 44 is ≤-40℃, preventing moisture from condensing inside the airbag and causing corrosion or freezing, ensuring a clean and dry air source; the flow regulating valve 45 is electrically connected to the DCS control module 5, which can precisely adjust the inflation volume and control the airbag expansion rate (e.g., 30~50mm / s) to avoid positioning deviation due to excessive expansion; the check valve 42 is located between the inflation pump and the filter 43 to prevent gas backflow and ensure air circuit safety; the pressure sensor 46 has a detection accuracy of ≤±0.01MPa, monitors the pressure inside the airbag in real time, provides pressure feedback signals to the DCS control module 5, and assists in judging the airbag sealing status (the airbag pressure is higher than the full load at low load).

[0024] Based on the above basic implementation method, in a specific embodiment, the airbag includes an airbag body 21 disposed on the inner wall of the flue 1, and a protective layer 22 disposed on the outer side of the airbag body 21.

[0025] Specifically, the protective layer 22 can deform synchronously with the expansion and contraction of the airbag body 21, thereby protecting the airbag body 21 from wear and corrosion without affecting its normal operation.

[0026] In one specific embodiment, the sensing unit is a capacitive sensor 24, and the distance between the sensing unit and each sensing unit is in the range of 1 to 5 mm; the air path control module 4 also includes a filter 43 and a dehumidifier 44 arranged sequentially on the pipeline between the inflation unit and the air bag; the partition plate 31 is a U-shaped partition plate, and each heat exchange partition 33 includes at least: a first partition 33a, a second partition 33b, a third partition 33c, a fourth partition 33d, and a fifth partition 33e arranged sequentially along the inner wall of the flue towards the central area of ​​the flue.

[0027] In this embodiment, the air circuit control module 4 also includes a connecting pipe 47, which is made of stainless steel and has a diameter of 30-80mm to ensure that the air source entering the airbag assembly is clean and dry, without the risk of corrosion or scaling.

[0028] Furthermore, the first zone 33a corresponds to full load, 90%-100% of the rated load; the second zone 33b corresponds to medium-high load, 70%-90% of the rated load; the third zone 33c corresponds to medium load, 60%-70% of the rated load; the fourth zone 33d corresponds to medium-low load, 40%-60% of the rated load; and the fifth zone 33e corresponds to low load, 30%-40% of the rated load.

[0029] In another specific embodiment, the partition plate 31 is a stainless steel partition plate, and the partition plate 31 is integrally formed with the heat exchanger of the heat exchange assembly 3; the length of the cross-section airbag assembly 2 ranges from 1.5 to 3 m, and the initial thickness of the airbag ranges from 50 to 100 mm.

[0030] In this embodiment, the maximum expansion thickness of the airbag is designed according to the number of heat exchange zones and the required flow area, so that the flow area of ​​flue 1 is precisely adjustable within the range of 30% to 100% (the flow area is the largest when the load is full and the smallest when the load is low), which is suitable for typical zones corresponding to 30% to 100% rated load of coal-fired units.

[0031] In one specific embodiment, the cross-section airbag assembly 2 is connected to the inner wall of the flue 1 via the connector 6, and a high-temperature resistant sealing gasket 23 is provided at the connection position between the cross-section airbag assembly 2 and the flue 1.

[0032] Furthermore, connector 6 is a clamp or a connecting flange.

[0033] In another specific embodiment, the air circuit control module 4 also includes a flow regulating valve 45 and a check valve 42. The flow regulating valve 45 is installed on the pipeline between the dehumidifier 44 and the air bag, and the check valve 42 is installed on the pipeline between the inflation unit and the filter 43. The flow regulating valve 45 is electrically connected to the DCS control module 5, and a sealing strip is provided at the connection between the pipeline and the air bag.

[0034] Furthermore, in this embodiment, the DCS control module 5 serves as the system's control core, realizing automated positioning adjustment, safety monitoring, and ash removal control. The DCS control module 5 is electrically connected to the capacitive sensor and the air pump, and has built-in "sensor signal-position" association logic. The airbag's initial pressure is zero. After determining the target positioning position based on the coal-fired unit's load requirements, the air pump is started. When the capacitive sensor first senses the partition plate sensing unit, it is determined to be "first partition 33a" (full load, minimum airbag expansion). The DCS control module 5 controls the air pump to stop and records the position number. If the target position is "second partition 33b" or "third partition 33c",... In subsequent low-load positions, the DCS control module 5 restarts the inflation pump after a 1-2 second delay. The airbag continues to inflate until the sensor detects the sensing unit at the corresponding target position (the low-load position corresponds to the maximum expansion). The inflation pump then stops, completing precise positioning. During depressurization and retraction, the airbag contracts, and the sensor sequentially senses the sensing units of each partition plate in reverse order (from low load to full load). The DCS automatically determines and records the current retraction position until the airbag returns to its initial state (pressure zero, corresponding to the full-load partition), preventing over-retraction or under-retraction. The pressure drop rate threshold is set to 0.02 MPa / h. When the pressure sensor 46 detects that the pressure drop rate inside the airbag exceeds this threshold, it is determined that the airbag is leaking, and an audible and visual alarm signal is immediately issued. The alarm time, current positioning position, pressure change data, and corresponding load conditions are recorded to remind personnel to perform timely maintenance and prevent uncontrolled flue gas flow due to airbag failure.

[0035] Furthermore, in this embodiment, the DCS control module 5 includes a controller 51, an audible and visual alarm 52, and a display terminal 53. A smoke temperature sensor 7 and a differential pressure sensor 8 are also installed on the flue 1.

[0036] Specifically, the DCS control module 5 is also used to realize the dust removal function: it controls the airbag assembly to perform inflation-deflation cycle at regular intervals, and generates airflow disturbance through the periodic change of the flow cross section to blow away the dust accumulation on the inner wall of the flue 1 and the surface of the heat exchanger tube bundle. The dust removal cycle is 2 to 8 hours, the single cycle time is 30 to 60 seconds, and the number of cycles is 2 to 3 times. During the dust removal process, the DCS control module 5 records the temporary expansion position of the airbag, and automatically restores it to the positioning position before dust removal after the dust removal is completed.

[0037] In another embodiment, the present invention also provides a method for preventing ash accumulation heat exchange by adjusting the flue gas flow cross section. The method is implemented using the above-mentioned flue gas flow cross section adjustment system for preventing ash accumulation, and includes the following steps: When the coal-fired unit is running, the DCS control module 5 collects pressure sensor signals and operating parameters such as flue gas temperature and pressure difference at the inlet and outlet of the heat exchanger in real time, and determines the target location as "first zone" (full load) according to the load demand of the coal-fired unit; the initial pressure of the airbag is zero, and the initial thickness is 50mm (minimum expansion). Start the air pump. After the gas is filtered and dehumidified, it is introduced into the cross-section airbag assembly 2. Adjust the flow regulating valve 45 to 100% to control the airbag expansion rate to 50mm / s. The airbag begins to expand radially along the flue. When the airbag inflates to a thickness of 80mm (initial thickness, minimum expansion amount), the capacitive sensor 24 generates a sensing signal with the sensing unit of the first partition plate (full load partition). The signal is transmitted to the DCS control module 5, which controls the air pump to stop running within 0.5 seconds. The DCS automatically records this position as "first partition 33a" (full load). At this time, the flue flow cross section matches the full load partition (maximum flow area), and the flue gas velocity is stable at 14m / s. If the target position is "fourth partition 33d" (low load 30%-40% of rated load), the DCS control module 5 restarts the air pump after a 1-second delay. The flow regulating valve opening is gradually adjusted, and the airbag continues to inflate. When sensing "second partition 33b" (medium-high load) and "third partition 33c" (medium-low load) in sequence, the machine briefly pauses to record, and then continues to inflate to a thickness of 250mm (maximum expansion amount). After the sensor senses the fourth sensing unit (low load partition), the air pump stops, completing the positioning. At this time, the flue gas velocity is stable at 9m / s. The pressure sensor monitors the pressure inside the airbag in real time and feeds it back to the DCS control module 5. The inflation volume is dynamically adjusted through the flow regulating valve 45 to maintain the pressure stable within the preset range (0.2MPa at full load and 0.3MPa at low load). If the pressure drop rate exceeds 0.02MPa / h within 1 hour, a leak alarm is immediately issued, and the alarm information and current location are displayed on the terminal 53. According to the preset cleaning cycle (e.g., 4 hours), the DCS control module 5 starts the cleaning program, controlling the air pump to increase the airbag pressure to 0.4MPa (corresponding to a maximum expansion thickness of 280mm) and hold it for 15 seconds; then quickly depressurize it to 0.1MPa (corresponding to a thickness of 100mm) and hold it for 10 seconds; repeat the above inflation-deflation cycle 3 times, with each cycle lasting 50 seconds; the drastic change in the flow cross-section generates an airflow velocity fluctuation of ±5m / s, forming a reverse flushing airflow to blow away the ash accumulated on the surface of the flue and heat exchanger tube bundle; after the cleaning is completed, the DCS control module 5 controls the airbag to inflate to the pre-cleaning position (e.g., position four). When the load of the coal-fired unit needs to switch to "Second Zone 33b" (medium-high load, 70%-90% of rated load) due to load changes, the DCS control module 5 controls the air bladder to release air. During the depressurization process, the capacitive sensor 24 sequentially senses the sensing units of the fourth zone 33d, the third zone 33c, and the second zone 33b. The DCS automatically judges and records the retraction position until the air bladder expansion thickness returns to 150mm (the thickness corresponding to position two). The air pump stops, and at this time the flue flow cross section matches the medium-high load zone, and the flue gas velocity stabilizes at 13m / s. When a coal-fired unit is shut down for maintenance, the airbag assembly is disassembled using flanges or clamps to check the integrity of the outer coating, the sealing performance of the airbag body 21, the conductivity of the capacitive sensor 24, and the condition of the sealing gaskets at the connection points. After cleaning the surface dust, the capacitive sensor 24 is tested for conductivity. If a sensor malfunction is found, it is replaced with a sensor of the same model. If the coating is damaged, it is repaired locally with a special repair agent. If the airbag body 21 is leaking, it is replaced entirely. After repair or replacement, the airtightness and positioning accuracy are tested. The airbag is inflated to each positioning position. If the sensor can accurately trigger the sensing, the DCS records the number normally, and the pressure drop is ≤0.01MPa / 2 hours, it is considered qualified. Then it is reinstalled and reset.

[0038] To aid in a better understanding of the present invention, a more comprehensive and specific embodiment is described. In this embodiment, one aspect of the present invention provides an anti-ash accumulation heat exchange system for adjusting the flue gas flow cross-section, including a flue duct 1, on which: The cross-section airbag assembly 2 includes an airbag disposed on the inner wall of the flue 1 and a sensing unit disposed on the side of the airbag facing the heat exchange assembly 3; the heat exchange assembly 3 is disposed in the downstream flue 1 of the cross-section airbag assembly 2, and the heat exchange assembly 3 includes multiple heat exchange zones 33, each heat exchange zone 33 being provided with a sensing unit 35 corresponding to the sensing unit; the air path control module 4 includes an inflation unit 41 connected to the airbag pipeline and a pressure sensing unit 46 disposed inside the airbag; and a DCS control module 5, which is electrically connected to the sensing unit and the air path control module 4 respectively; wherein, the heat exchange zone 33 is composed of a partition plate 31 and a tube bundle partition plate 32 in the heat exchange assembly 3, the sensing unit 35 is disposed on the partition plate, and the DCS control module 5 controls the start and stop of the inflation unit 41 according to the signals of the sensing unit and the sensing unit 35.

[0039] In this embodiment, the airbag includes an airbag body 21 disposed on the inner wall of the flue 1 and a protective layer 22 disposed on the outer side of the airbag body 21; the sensing unit is a capacitive sensor 24, and the distance between the sensing unit and each sensing unit is 1-5 mm; the air path control module 4 also includes a filter 43 and a dehumidifier 44 disposed sequentially on the pipeline between the inflation unit 41 and the airbag; the partition plate 31 is a U-shaped partition plate, and each heat exchange partition 33 includes at least: a first partition 33a, a second partition 33b, a third partition 33c, a fourth partition 33d, and a fifth partition 33e disposed sequentially along the inner wall of the flue towards the center area of ​​the flue; the partition plate 31 1 is a stainless steel partition, and the partition 31 is integrally formed with the heat exchanger of the heat exchange component 3; the length of the cross-section airbag component 2 ranges from 1.5 to 3m, and the initial thickness of the airbag ranges from 50 to 100mm; the cross-section airbag component 2 is connected to the inner wall of the flue 1 through the connector 6; a high-temperature resistant sealing gasket is provided at the connection position between the cross-section airbag component 2 and the flue 1; the gas circuit control module 4 also includes a flow regulating valve 45 and a check valve 42. The flow regulating valve 45 is set on the pipeline between the dehumidifier and the airbag, and the check valve 42 is set on the pipeline between the air filling unit and the filter 43. The flow regulating valve 45 is electrically connected to the DCS control module 5, and a sealing strip is provided at the connection between the pipeline and the airbag.

[0040] In this embodiment, another aspect of the present invention provides a method for preventing ash accumulation heat exchange by adjusting the flue gas flow cross-section. This method is implemented using the aforementioned flue gas flow cross-section adjustment system for preventing ash accumulation, and includes the following steps: S1: DCS control module 5 collects real-time signals from the pressure sensing unit of the gas path control module and the inlet and outlet flue gas temperature and pressure difference operating parameters of heat exchange component 2, and determines the target positioning position according to the load demand of the coal-fired unit. S2: Start the inflation unit 41. The filtered and dehumidified gas is introduced into the cross-section airbag assembly 2, and the airbag begins to inflate. S3: During the expansion process, the sensing unit passes through each sensing unit 35 in sequence. The DCS control module 5 assigns a logical number to the partition position corresponding to each sensing unit 35 according to the triggering order of each sensing unit 35, and drives the airbag to stop at different partition positions according to the target load command. S4: Pressure sensing unit 46 monitors the pressure inside the airbag in real time and feeds it back to DCS control module 5. DCS control module 5 adjusts the inflation volume to maintain the pressure stable within the preset range. If the pressure drop rate exceeds the set threshold, the DCS control module 5 will issue a leak alarm. If the airbag needs to be switched to another positioning position, the DCS control module 5 will control the airbag to deflate and then repeat steps S2 to S3.

[0041] In summary, the embodiments disclosed herein have at least the following technical effects: This invention controls the expansion of the airbag within flue 1, occupying a portion of the flow cross-section, thereby actively reducing the flue gas flow area and increasing the local flue gas velocity under low load and low exhaust volume conditions; making the flue gas velocity within flue 1 approach or exceed the critical flow velocity for fly ash transport, significantly reducing the probability of fly ash deposition on the inner wall of the flue, elbows, and the surface of the heat exchanger tube bundle; suppressing ash accumulation from the perspective of flow conditions, avoiding the lag of traditional passive cleaning methods; Through the cooperation of the sensing unit and the zone sensing unit, the airbag can be accurately positioned and docked between multiple heat exchange zones; the DCS control module 5 can dynamically select the target zone position according to the load demand of the coal-fired unit, the flue gas temperature and pressure difference and other operating parameters; thus, the flue gas flow state and heat exchange intensity can be flexibly adjusted with load changes to meet the stable operation requirements of the coal-fired unit within the range of 30% to 100% rated load. By reducing the formation of ash and dust layers, the thermal resistance of the heat exchanger tube bundle surface is reduced; the heat exchange components are kept in a better heat transfer state for a long time, avoiding the decline in heat exchange efficiency due to ash accumulation; at the same time, the increase in flue gas side resistance is reduced, the system pressure drop is reduced, and the overall thermal economy of the coal-fired unit is improved. By setting a capacitive sensing unit and a corresponding sensing unit 35, non-contact identification of the airbag position is achieved; this avoids the problems of jamming, wear and failure of traditional baffle doors and mechanical actuators in high temperature and high dust environments; and helps to improve the long-term operational reliability of the system under complex flue gas conditions. This invention eliminates the complex baffle door transmission structure, reducing the number of mechanical moving parts; it does not rely on high-energy-consuming steam or sonic soot blowing devices, reducing system operating energy consumption; and it achieves anti-ash accumulation function through airbag adjustment, resulting in a compact structure and more convenient maintenance and repair. The pressure inside the airbag is monitored in real time by the pressure sensing unit 46 in the air circuit control module 4; the DCS control module 5 can adjust the inflation volume according to the pressure change and issue a leakage alarm when the pressure drops abnormally; effectively preventing the airbag failure or abnormal operating conditions from affecting the operation of the flue gas system and improving the safety of system operation. The cross-section airbag assembly 2 can be installed on the inner wall of the existing flue 1 through the connector 6, which is suitable for new coal-fired units or the renovation of existing coal-fired units; it does not require large-scale modification of the original heat exchanger structure, and the engineering implementation is easy; it is particularly suitable for application scenarios where coal-fired units need to undertake deep peak shaving and flexible operation in the context of the increasing proportion of new energy.

[0042] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A flue gas flow cross-section adjustment system for preventing ash accumulation heat exchange, characterized in that, Including the flue, which is equipped with: The cross-section airbag assembly includes an airbag disposed on the inner wall of the flue and a sensing unit disposed on the side of the airbag facing the heat exchange assembly. The heat exchange assembly is disposed in the flue downstream of the cross-section airbag assembly. The heat exchange assembly includes multiple heat exchange zones, and each heat exchange zone is provided with a sensing unit corresponding to the sensing unit. The airway control module includes an inflation unit connected to the airbag tubing; and The DCS control module is electrically connected to the sensing unit and the pneumatic control module respectively; The heat exchange partition consists of partition plates and tube bundle partition plates within the heat exchange assembly. The sensing unit is disposed on the partition plate, and the DCS control module controls the start and stop of the inflation unit based on the signals from the sensing unit.

2. The flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to claim 1, characterized in that, The airbag includes an airbag body disposed on the inner wall of the flue and a protective layer disposed on the outer side of the airbag body.

3. The flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to claim 1, characterized in that, The sensing unit is a capacitive sensor, and the distance between the sensing unit and each of the sensing units ranges from 1 to 5 mm.

4. The anti-ash accumulation heat exchange system for adjusting the flue gas flow cross-section according to claim 1, characterized in that, The air circuit control module also includes a filter and a dehumidifier arranged sequentially on the pipeline between the inflation unit and the airbag.

5. The anti-ash accumulation heat exchange system for flue gas flow cross-section adjustment according to claim 1, characterized in that, The partition is a U-shaped partition, and each heat exchange zone includes at least a first zone, a second zone, a third zone, a fourth zone, and a fifth zone arranged sequentially along the inner wall of the flue towards the center area of ​​the flue.

6. The flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to claim 1, characterized in that, The partition plate is made of stainless steel and is integrally formed with the heat exchanger of the heat exchange assembly.

7. The anti-ash accumulation heat exchange system for flue gas flow cross-section adjustment according to claim 1, characterized in that, The length of the cross-sectional airbag assembly ranges from 1.5 to 3 m, and the initial thickness of the airbag ranges from 50 to 100 mm.

8. The anti-ash accumulation heat exchange system for flue gas flow cross-section adjustment according to claim 1, characterized in that, The cross-section airbag assembly is connected to the inner wall of the flue via a connector, and a sealing gasket is provided at the connection position between the cross-section airbag assembly and the flue.

9. A flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to any one of claims 4 to 8, characterized in that, The air circuit control module also includes a flow regulating valve and a check valve. The flow regulating valve is installed on the pipeline between the dehumidifier and the air bag, and the check valve is installed on the pipeline between the inflation unit and the filter. The flow regulating valve is electrically connected to the DCS control module, and a sealing strip is provided at the connection between the pipeline and the air bag.

10. A method for preventing ash accumulation and heat exchange by adjusting the flue gas flow cross-section, characterized in that, The method is implemented using a flue gas flow cross-section adjustment anti-ash accumulation heat exchange system according to any one of claims 1 to 9, and includes the following steps: S1: The DCS control module collects the pressure sensing unit signal of the gas path control module and the inlet and outlet flue gas temperature and pressure difference operating parameters of the heat exchange component in real time, and determines the target positioning position according to the load demand of the coal-fired unit. S2: The inflation unit is activated, and the filtered and dehumidified gas is introduced into the cross-sectional airbag assembly, and the airbag begins to inflate. S3: During the expansion process, the sensing unit passes through each of the sensing units in sequence. The DCS control module assigns a logical number to the partition position corresponding to each sensing unit according to the triggering order of each sensing unit, and drives the airbag to stop at different partition positions according to the target load command. S4: The pressure sensing unit monitors the pressure inside the airbag in real time and feeds it back to the DCS control module. The DCS control module adjusts the inflation volume to maintain the pressure stable within a preset range. If the pressure drop rate exceeds a set threshold, the DCS control module issues a leak alarm. If the airbag needs to be switched to another positioning position, the DCS control module controls the airbag to deflate and then repeats steps S2 to S3.

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