A method for operating a boiler tubular air preheater in compartments

Abstract

The present application provides a kind of boiler tubular air preheater compartment operation method, belong to circulating fluidized bed boiler equipment operation control technical field;Including the following steps:S1, compartment structure layout: the low temperature section air inlet wind chamber of the tubular air preheater is separated into upper chamber, middle chamber, lower chamber three independent ventilation chambers along vertical height;S2, compartment operation mode determination: the collection and dispersion control system real-time acquisition boiler actual load, preheater low temperature section tube wall metal temperature, flue gas acid dew point temperature, denitration device ammonia escape concentration parameter;S3, single compartment isolation heat exchange regulation: after starting compartment operation mode, the collection and dispersion control system output control signal closes middle isolation baffle or lower isolation baffle, the compartment corresponding to the closed baffle is cut off cold air input, exit flue gas heat exchange process.The application realizes the accurate operation of air preheater self-adaptive working condition, and gives consideration to equipment safety and unit operation economy.

Description

Technical Field

[0001] The present invention provides a compartmentalized operation method for a boiler tubular air preheater, which belongs to the technical field of operation control of circulating fluidized bed boiler equipment. Background Art

[0002] Circulating fluidized bed boilers are widely applied in the fields of thermal power generation and cogeneration by virtue of their characteristics of wide fuel adaptability, high combustion efficiency and excellent environmental protection performance. The horizontal tubular air preheater is the core heat exchange equipment of this type of boiler, which mainly uses the waste heat of low-temperature flue gas at the boiler tail to heat the supply air, reduces the heat loss of exhaust flue gas, and improves the operation economy of the unit.

[0003] At present, all existing tubular air preheaters adopt the operation mode of synchronous ventilation and heat exchange in all compartments, which has obvious technical defects under the low-load operation condition of the unit. When the unit load is lower than 70% of the rated load, the boiler exhaust gas temperature drops significantly, the metal temperature of the tube wall at the low-temperature section of the air preheater is easy to drop below the acid dew point temperature of the flue gas, and sulfur trioxide in the flue gas combines with water vapor to form sulfuric acid vapor, which condenses on the heat exchange tube wall and causes the problem of low-temperature acid corrosion. At the same time, the condensed sulfuric acid will adhere to the fly ash in the flue gas and the ammonia escaped from the denitration system to form viscous ammonium bisulfate deposits, causing ash blockage of the preheater and air duct blockage, further aggravating problems such as decreased heat exchange efficiency, increased exhaust gas temperature, and increased power consumption of the fan, which will cause insufficient boiler air volume and unstable combustion in severe cases, and affect the safe and stable operation of the unit.

[0004] In the prior art, for the problems of low-temperature corrosion and ash blockage of air preheaters, auxiliary means such as enhanced soot blowing, inlet air temperature rise, and denitration ammonia injection strategy optimization are mostly adopted. The above methods can only alleviate the fault degree, cannot fundamentally solve the problem of low-temperature condensation on the tube wall under low-load working conditions, and have disadvantages such as soot blowing causing tube wall loss, increased energy consumption, and limited ammonia escape control accuracy, which cannot meet the working condition requirements of the unit for long-term deep low-load operation. Based on this, there is an urgent need for an air preheater operation method that can be precisely regulated, adapt to working conditions, and effectively avoid low-temperature corrosion and ash blockage. Contents of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a compartmentalized operation method for a boiler tubular air preheater, so as to solve the technical problems of condensation and corrosion on the tube wall at the low-temperature section of the air preheater, ash deposition and blockage, and poor operation stability when the unit is under low load in the existing full-compartment operation mode, realize the self-adaptive and precise operation of the air preheater, and give consideration to both equipment safety and unit operation economy.

[0006] In order to solve the above problems, the technical solution proposed by the present invention is: a compartmentalized operation method for a boiler tubular air preheater, which is used for the horizontal tubular air preheater matched with circulating fluidized bed boilers of 300MW, 330MW and 350MW classes, comprising the following steps: S1. Compartmentalized Structure: The air inlet chamber of the low-temperature section of the tubular air preheater is vertically divided into three independent ventilation compartments: an upper compartment, a middle compartment, and a lower compartment. The upper compartment has no partitions and maintains a continuous ventilation path. The ventilation passage of the middle compartment is equipped with a middle isolation baffle, and the ventilation passage of the lower compartment is equipped with a lower isolation baffle. Both the middle and lower isolation baffles are connected to the unit's distributed control system, which enables independent full-open and full-close interlocking control. S2. Determination of compartmentalized operation mode: The distributed control system collects the actual load of the boiler, the metal temperature of the tube wall in the low-temperature section of the preheater, the acid dew point temperature of the flue gas, and the ammonia escape concentration of the denitrification device in real time. When the actual load of the boiler is lower than 70% of the rated load and the metal temperature of the tube wall in the low-temperature section of the preheater is lower than the acid dew point temperature of the flue gas, the low-temperature anti-corrosion and ash suppression compartmentalized operation mode is automatically started. S3. Single-compartment isolation heat exchange control: After starting the compartment operation mode, the distributed control system outputs a control signal to close the middle isolation baffle or the lower isolation baffle. The compartment corresponding to the closed baffle is cut off from cold air input and exits the flue gas heat exchange process. Only the upper compartment and the compartment corresponding to the unclosed baffle are allowed to participate in heat exchange. By reducing the effective heat exchange area of ​​the low temperature section, the average metal temperature of the preheater heat exchange tube wall is raised to above the flue gas acid dew point. S4. Warehouse rotation control: The maximum continuous isolation time of a single warehouse is set to 2 hours; when the cumulative isolation time of a single warehouse reaches the set threshold, the distribution control system interlocks and switches the working state of the two isolation baffles, the original isolated and shut-down warehouse resumes ventilation, and the original ventilated warehouse switches to the isolation state, realizing the alternating isolation operation of the middle warehouse and the lower warehouse. S5. Full Chamber Heat Exchange Recovery: When the actual load of the boiler rises to 70% or more of the rated load, or when the metal temperature of the tube wall in the low-temperature section of the preheater continues to be 10°C or more higher than the acid dew point temperature of the flue gas, the distributed control system will simultaneously open the middle isolation baffle and the lower isolation baffle, and the upper chamber, middle chamber and lower chamber will be ventilated together, and the preheater will resume full chamber heat exchange operation.

[0007] Furthermore, in the step of determining the compartmentalized operation mode, the flue gas acid dew point temperature is calculated in real time through an online dynamic calculation model; the distributed control system calculates the dynamic flue gas acid dew point in real time based on the sulfur content of the coal received, the calcium oxide content of the flue gas fly ash, and the ammonia escape concentration of the denitrification device, and uses the dynamic calculation result as the basis for judging the operating condition.

[0008] Furthermore, both the middle isolation baffle and the lower isolation baffle are equipped with valve position feedback detection mechanisms; after the signal of the baffle being fully closed is fed back to the distributed control system, the distributed control system synchronously increases the speed of the primary air fan and the secondary air fan to compensate for the increase in ventilation resistance caused by the isolation of the compartment and stabilize the total air volume required for boiler combustion.

[0009] Furthermore, in the compartment rotation control step, a 30-second buffer transition time is set for the baffle switching process; during the buffer time, the opening of the middle isolation baffle and the lower isolation baffle are synchronously adjusted slightly and linearly to weaken the step disturbance of the air volume in the air duct and reduce the fluctuation of the induced draft fan output and the instantaneous fluctuation of the exhaust temperature.

[0010] Furthermore, it also includes a coordinated soot blowing step for the isolation chamber: when the middle or lower chamber is in an isolated shutdown state, the steam soot blowing device of the corresponding chamber is put into operation simultaneously. The high temperature of the pipe wall of the isolation chamber is used to pyrolyze the ammonium bisulfate deposits, peel off the fly ash attached to the pipe wall, suppress ash blockage and reduce the heat loss of flue gas.

[0011] Furthermore, the middle isolation baffle and the lower isolation baffle adopt a double-layer sealing plate structure. When the baffle is fully closed, the air leakage rate of the air duct is no higher than 0.5%, which blocks the cold air flow channel and avoids sulfuric acid condensation corrosion caused by local pipe wall temperature drop.

[0012] Furthermore, the distributed control system has built-in fault-safe interlocking logic; when any isolation baffle experiences mechanical jamming or abnormal valve position feedback signal, the distributed control system will force all isolation baffles to open fully and output audible and visual alarm signals, automatically exiting the compartment operation mode to ensure continuous and stable boiler operation.

[0013] Furthermore, the distributed control system records and stores the cumulative isolation time of the middle compartment and the lower compartment in real time; under the long-term low-load continuous operation of the unit, the distributed control system automatically balances the cumulative isolation time of the two compartments to prevent long-term ash accumulation in one compartment and fatigue damage to the heat exchange tubes due to alternating hot and cold temperatures.

[0014] Due to the adoption of the above technical solution, the beneficial effects of the present invention's method for compartmentalized operation of a boiler tube air preheater are as follows: 1. This invention, through a three-compartment independent partition structure design and an adaptive compartment operation strategy, precisely reduces the effective heat exchange area of ​​the preheater under low-load conditions of the unit, actively increases the metal temperature of the tube wall in the low-temperature section, avoids the problems of flue gas acid condensation and low-temperature corrosion from the root, and completely solves the inherent defects of the traditional full-compartment operation mode.

[0015] 2. By alternating and isolating the middle and lower compartments, and coordinating with the isolation compartments to blow soot and control the duration, the heat exchange tubes are effectively blocked and ash accumulates, avoiding long-term fatigue wear on one side of the equipment, significantly extending the service life of the air preheater, and reducing the frequency of equipment maintenance and operating costs.

[0016] 3. Set a 30-second buffer switching sequence, fan output compensation control and fault safety interlock logic to completely eliminate the disturbance of air volume and flue gas temperature caused by compartment switching, ensure the stability of boiler combustion, avoid the operational risks caused by equipment failure, and improve the safety and reliability of unit operation.

[0017] 4. The dynamic flue gas acid dew point calculation model is adopted to adapt to different coal qualities and different denitrification operating conditions, with higher discrimination accuracy and strong adaptive operation strategy. It can adapt to the variable load operation requirements of circulating fluidized bed boilers of all levels from 300MW to 350MW, with a wide range of applications and significant energy saving and efficiency improvement effects. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the three-compartment structure layout of the low-temperature section of the air preheater in the boiler tube air preheater compartment operation method of the present invention. Figure 2 This is a flowchart illustrating the overall control process of a compartmentalized operation method for a boiler tube air preheater according to the present invention. Figure 3 This is a sequence control curve diagram for the alternating isolation and rotation operation of the middle compartment and the lower compartment in a boiler tube air preheater compartment operation method according to the present invention. Figure 4 This is a fault safety interlock logic block diagram for the compartmentalized operation mode of a boiler tube air preheater according to the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Conventional low-load steady-state operation of a 300MW unit This embodiment is applied to a horizontal tubular air preheater for a 300MW-class circulating fluidized bed boiler. The unit operates normally with a stable load of 180MW, which is 60% of the rated load and lower than the 70% rated load threshold, thus meeting the preconditions for compartmentalized operation.

[0021] First, the S1 compartmentalized structure is implemented, vertically dividing the air inlet chamber of the low-temperature section of the air preheater into three independent ventilation compartments: upper, middle, and lower. The upper compartment is fully open without partitions, while the middle and lower compartments are equipped with double-layer sealed plate-type isolation baffles. The air leakage rate of the baffles is controlled within 0.5%. All baffles are connected to the unit's DCS distributed control system, which has independent full-open, full-interlock control, and valve position feedback functions.

[0022] During operation, the DCS system collects parameters such as unit load, pipe wall temperature, and ammonia slip concentration in real time. Through a dynamic calculation model, combined with the current operating conditions of 0.8% sulfur content of the coal received, 8.2% calcium oxide content in fly ash, and 2.1 ppm ammonia slip concentration, the system calculates the flue gas acid dew point temperature to be 92℃. At this time, the average metal temperature of the pipe wall in the low-temperature section of the preheater is 87℃, which is lower than the dynamic acid dew point temperature. The DCS system automatically triggers the low-temperature anti-corrosion and ash-suppressing compartment operation mode.

[0023] Single-compartment isolation heat exchange control is implemented. Initially, the lower isolation baffle is closed, cutting off the cold air input to the lower compartment and exiting the heat exchange process. Only the upper and middle compartments participate in flue gas heat exchange. By reducing the effective heat exchange area of ​​the low-temperature section by 1 / 3, the average metal temperature of the preheater tube wall rapidly increases to 95℃, higher than the flue gas acid dew point temperature, completely eliminating sulfuric acid condensation corrosion. After the baffle fully closed valve position signal is fed back to the DCS, the system automatically fine-tunes the output of the primary and secondary air fans, increasing the total ventilation volume by 3.2%, accurately compensating for the air volume loss caused by the lower compartment isolation, and maintaining stable boiler combustion air volume.

[0024] Initiate the compartment rotation control and coordinated soot blowing program, setting the maximum continuous isolation time for a single compartment to 2 hours. During the isolation operation of the lower compartment, its steam soot blowing device is simultaneously activated to utilize the high-temperature pipe wall pyrolysis of residual ammonium bisulfate and strip away fly ash, preventing ash blockage and accumulation. When the cumulative isolation time of the lower compartment reaches 2 hours, the system initiates a 30-second buffer transition sequence, with the two dampers synchronously and linearly adjusting their opening to smoothly complete the operating condition switch. The lower compartment resumes ventilation and heat exchange, while the dampers of the middle compartment are fully closed for isolation, achieving alternating operation.

[0025] Under the operating conditions of this embodiment, the unit operates in a long-term low-load steady-state manner. The DCS system balances the cumulative isolation time of the middle and lower compartments in real time, avoiding fatigue damage to equipment on one side. No low-temperature corrosion or ash blockage occurs throughout the process, the stability of flue gas temperature is improved, the fan power consumption is reduced by 4.5% compared to the traditional operating mode, and the frequency of equipment maintenance is significantly reduced.

[0026] Example 2: Deep Low Load Fluctuation Operation Condition of 330MW Unit This embodiment is applied to a 330MW-class circulating fluidized bed boiler, which operates under deep peak shaving conditions. The load fluctuates between 165MW and 220MW, with the lowest load being 50% of the rated load. The load fluctuates frequently, the operating conditions are complex, and the requirements for the stability of the preheater are higher.

[0027] The equipment structure layout is the same as in Example 1, with a three-compartment independent ventilation structure, and the isolation baffle adopts a double-layer sealing structure. The DCS system integrates dynamic acid dew point calculation, timing control, and fault interlocking logic.

[0028] Operating Condition Determination and Mode Start-up: When the unit load drops to 220MW (66.7% rated load), the DCS real-time monitoring shows that, combined with the coal sulfur content of 0.6%, ammonia slip concentration of 1.8ppm, and fly ash calcium oxide content of 7.5%, the dynamic calculation shows that the flue gas acid dew point is 90℃ and the preheater tube wall temperature is 85℃, which meets the conditions for compartmentalized operation. The compartmentalized operation mode is automatically started. Initially, the middle isolation baffle is closed, the middle compartment exits heat exchange, and the upper and lower compartments maintain ventilation and heat exchange.

[0029] Heat exchange regulation and disturbance suppression: After the central baffle is fully closed, the system automatically compensates for the fan output to stabilize the total air volume in the furnace. During compartment switching, a 30-second buffer transition sequence is strictly implemented to avoid step disturbances in air volume. In this embodiment, the unit load fluctuates frequently, with multiple instances of slight load increases and decreases. The DCS system dynamically judges the operating conditions in real time. When the load briefly rises to 72% of the rated load, but the pipe wall temperature is only 5°C above the acid dew point, the system maintains the compartment operation mode and does not blindly shut down, avoiding equipment disturbances caused by repeated switching of operating conditions.

[0030] Fault Interlock Protection: During the operation of this embodiment, if the feedback signal of the valve position of the middle isolation baffle is momentarily abnormal, the DCS system will immediately trigger the fault safety interlock logic, forcibly open all middle and lower isolation baffles, automatically exit the compartment mode, and output an audible and visual alarm to remind the operation and maintenance personnel to troubleshoot the fault. This ensures the continuous and stable operation of the boiler throughout the process, without the risk of air interruption or combustion fluctuation.

[0031] Operational recovery: When the unit load stabilizes and rises to 235MW (71.2% of rated load), and the preheater tube wall temperature remains 12°C above the acid dew point, the system simultaneously opens all isolation baffles, restoring full-compartment heat exchange operation. This embodiment effectively adapts to deep peak-shaving fluctuation conditions, completely resolving the issues of preheater low-temperature corrosion and operational disturbances during load changes, significantly improving equipment operational stability.

[0032] Example 3: Long-term low-load continuous operation of a 350MW unit This embodiment applies to a 350MW-class circulating fluidized bed boiler. Due to grid load demand, the unit maintains a low-load continuous operation of 210MW for a long time, with the load being 60% of the rated load. This is a long-term steady-state low-load condition, which is prone to problems such as ash accumulation in one side of the chamber and thermal fatigue damage to the heat exchange tubes.

[0033] The compartmentalized operation structure and control method of this invention are adopted, with three compartments ventilated in separate zones. The air leakage rate of the isolation baffle is ≤0.5%, preventing local low-temperature condensation caused by cold air crossflow. Based on real-time coal quality parameters and denitrification operation parameters, the DCS system dynamically calculates the flue gas acid dew point temperature to be 93℃, and the measured preheater tube wall temperature is 88℃, thus activating the compartmentalized anti-corrosion and ash suppression operation mode.

[0034] Initially, the lower compartment was shut down for isolation, while the upper and middle compartments operated for heat exchange, raising the pipe wall temperature to 96℃, which remained stable above the acid dew point. During the lower compartment isolation period, steam-assisted soot blowing was continuously implemented to regularly clean pipe wall deposits and prevent soot blockage at its source. A strict 2-hour single-compartment rotation mechanism was enforced, with a 30-second buffer time for smooth switching of compartment operation, avoiding fluctuations in induced draft fan output and flue gas temperature.

[0035] In response to the long-term, continuous, low-load operation characteristics of this embodiment, the DCS system employs a start-up duration balancing control logic. This logic tracks the cumulative isolation runtime of the middle and lower compartments in real time, automatically correcting the rotation sequence to prevent any single compartment from remaining in an isolated, stopped, or running state for extended periods. Continuous monitoring data over 15 days shows that the difference in cumulative isolation time between the middle and lower compartments is controlled within 2 hours, effectively preventing long-term dust accumulation on one side of the compartment and fatigue damage from alternating hot and cold temperatures on the heat exchange tubes. Equipment wear and dust accumulation rates are reduced by more than 60% compared to traditional methods.

[0036] When the unit load rises to above 245MW (70% of rated load) and the pipe wall temperature remains 11°C above the acid dew point, the system automatically resumes full-compartment heat exchange, the unit's heat exchange efficiency returns to the rated level, the exhaust heat loss is significantly reduced, and the unit's operating economy is greatly improved.

[0037] The present invention and its embodiments have been described above. This description is not restrictive. In short, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the present invention, such design should fall within the protection scope of the present invention.

Claims

1. A compartmentalized operation method for a boiler tubular air preheater, which is used for a horizontal tubular air preheater matched with circulating fluidized bed boilers of 300MW, 330MW and 350MW classes, characterized in that, Includes the following steps: S1. Compartmentalized Structure: The air inlet chamber of the low-temperature section of the tubular air preheater is vertically divided into three independent ventilation compartments: an upper compartment, a middle compartment, and a lower compartment. The upper compartment has no partitions and maintains a continuous ventilation path. The ventilation passage of the middle compartment is equipped with a middle isolation baffle, and the ventilation passage of the lower compartment is equipped with a lower isolation baffle. Both the middle and lower isolation baffles are connected to the unit's distributed control system, which enables independent full-open and full-close interlocking control. S2. Divisional operation mode determination: The distributed control system collects the actual load of the boiler, the metal temperature of the tube wall in the low temperature section of the preheater, the acid dew point temperature of the flue gas, and the ammonia escape concentration of the denitrification device in real time. When the actual load of the boiler is less than 70% of the rated load, and the metal temperature of the tube wall in the low-temperature section of the preheater is lower than the acid dew point temperature of the flue gas, the low-temperature anti-corrosion and ash-suppressing compartment operation mode will be automatically started. S3. Single-compartment isolation heat exchange control: After starting the compartment operation mode, the distributed control system outputs a control signal to close the middle isolation baffle or the lower isolation baffle. The compartment corresponding to the closed baffle is cut off from cold air input and exits the flue gas heat exchange process. Only the upper compartment and the compartment corresponding to the unclosed baffle are allowed to participate in heat exchange. By reducing the effective heat exchange area of ​​the low temperature section, the average metal temperature of the preheater heat exchange tube wall is raised to above the flue gas acid dew point. S4. Warehouse rotation control: The maximum continuous isolation time of a single warehouse is set to 2 hours; when the cumulative isolation time of a single warehouse reaches the set threshold, the distribution control system interlocks and switches the working state of the two isolation baffles, the original isolated and shut-down warehouse resumes ventilation, and the original ventilated warehouse switches to the isolation state, realizing the alternating isolation operation of the middle warehouse and the lower warehouse. S5. Full Chamber Heat Exchange Recovery: When the actual load of the boiler rises to 70% or more of the rated load, or when the metal temperature of the tube wall in the low-temperature section of the preheater continues to be 10°C or more higher than the acid dew point temperature of the flue gas, the distributed control system will simultaneously open the middle isolation baffle and the lower isolation baffle, and the upper chamber, middle chamber and lower chamber will be ventilated together, and the preheater will resume full chamber heat exchange operation.

2. The method for compartmentalized operation of a boiler tube air preheater according to claim 1, characterized in that: In the compartmentalized operation mode determination step, the flue gas acid dew point temperature is calculated in real time by an online dynamic calculation model; the distributed control system calculates the dynamic flue gas acid dew point in real time based on the sulfur content of the coal received, the calcium oxide content of the flue gas fly ash, and the ammonia escape concentration of the denitrification device, and uses the dynamic calculation result as the basis for judging the operating condition.

3. The method for compartmentalized operation of a boiler tubular air preheater according to claim 1, characterized in that: Both the middle and lower isolation baffles are equipped with valve position feedback detection mechanisms. After the signal of the baffle being fully closed is fed back to the distributed control system, the distributed control system synchronously increases the speed of the primary and secondary air fans to compensate for the increased ventilation resistance caused by the isolation of the compartments and stabilize the total air volume required for boiler combustion.

4. The method for compartmentalized operation of a boiler tube air preheater according to claim 1, characterized in that: In the compartment rotation control steps, a 30-second buffer transition time is set for the baffle switching process; During the buffer period, the opening of the middle isolation baffle and the lower isolation baffle are adjusted linearly and synchronously to weaken the step disturbance of the air volume in the duct and reduce the fluctuation of the output of the induced draft fan and the instantaneous fluctuation of the flue gas temperature.

5. A method for compartmentalized operation of a boiler tube air preheater according to claim 1, characterized in that: It also includes a coordinated soot blowing step for the isolation chamber: when the middle or lower chamber is in an isolated shutdown state, the steam soot blowing device of the corresponding chamber is put into operation simultaneously. The high temperature of the pipe wall of the isolation chamber is used to pyrolyze the ammonium bisulfate deposits, peel off the fly ash attached to the pipe wall, suppress ash blockage and reduce the heat loss of flue gas.

6. A method for compartmentalized operation of a boiler tubular air preheater according to claim 1, characterized in that: The middle and lower isolation baffles adopt a double-layer sealing plate structure. When the baffles are fully closed, the air leakage rate of the air duct is no higher than 0.5%, which blocks the cold air flow channel and avoids sulfuric acid condensation corrosion caused by local pipe wall temperature drop.

7. A method for compartmentalized operation of a boiler tube air preheater according to claim 1, characterized in that: The distributed control system has built-in fault-safe interlocking logic; when any isolation baffle is mechanically jammed or the valve position feedback signal is abnormal, the distributed control system will force all isolation baffles to open fully and output audible and visual alarm signals, automatically exit the compartment operation mode, and ensure the continuous and stable operation of the boiler.

8. A method for compartmentalized operation of a boiler tube air preheater according to claim 1, characterized in that: The distributed control system records and stores the cumulative isolation time of the middle compartment and the lower compartment in real time. Under the condition of long-term low-load continuous operation of the unit, the distributed control system automatically balances the cumulative isolation time of the two compartments to prevent long-term ash accumulation in one compartment and fatigue damage to the heat exchange tubes due to alternating hot and cold temperatures.

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