Boiler flue dusting collaborative control system and method based on deep peak regulation working condition

Abstract

The application discloses a boiler flue ash deposition collaborative control system and method based on a deep peak regulation working condition, and the method comprises the following steps: S1, collecting boiler operation and flue size parameters in real time, quantitatively calculating a theoretical ash deposition height and an additional load, and performing an over-standard judgment; S2, online measurement of an ash deposition coverage area, correction of the calculated value of S1 to obtain actual ash deposition parameters, and realization of double verification; S3, according to the ash deposition judgment results of S1 and S2 and the boiler working condition, through a "perception-decision-execution-feedback" whole-process technical closed loop, precise quantification, precise positioning and active inhibition of ash deposition are realized, flue overloading collapse is effectively prevented, and the safe and stable operation of the boiler under deep peak regulation is ensured.

Description

Technical Field

[0001] This invention belongs to the field of power plant boiler safety management and control, specifically, it relates to a collaborative management and control system and method for boiler flue gas duct ash accumulation based on deep peak shaving conditions. Background Technology

[0002] Currently, thermal power units generally operate under long-term, deep peak-shaving conditions. Under low-load conditions, the flue gas velocity in the boiler flue gas duct decreases significantly, resulting in a weakened fly ash carrying capacity and making it easy for large amounts of fly ash to accumulate in various horizontal flues, connecting air ducts, and wind boxes. If this is compounded by factors such as increased ash content in the coal fed into the furnace, operation of a single-sided fan, air preheater blockage, and abnormal positive pressure in the furnace, the ash accumulation rate will be further accelerated.

[0003] Dust accumulation not only reduces the effective cross-sectional area of ​​the flue, but also generates a huge additional load. When the dust accumulation height and load exceed the design values ​​of the flue reinforcement ribs and supports, it can easily lead to serious safety accidents such as duct tearing, support overload, expansion joint tearing, or even the collapse of the entire duct.

[0004] Traditional methods for controlling ash accumulation in flue gas ducts rely primarily on manual experience, resulting in a simplistic inspection process lacking quantifiable standards and online monitoring capabilities. Furthermore, the control measures lack specificity and fail to establish a proactive ash suppression mechanism that integrates with operational conditions, thus failing to meet the safety requirements for flue gas duct operation under conditions of deep peak shaving. Summary of the Invention

[0005] To address the above deficiencies, this invention provides a collaborative control system and method for boiler flue gas duct ash accumulation based on deep peak-shaving conditions, comprising the following steps:

[0006] S1. Ash Accumulation Quantification and Exceedance Judgment: Real-time acquisition of boiler operating parameters and flue gas duct dimensions to calculate the theoretical ash accumulation height and additional ash accumulation load in different flue gas duct areas. The calculation results are compared with the set threshold for exceeding the standard to determine whether the dust accumulation exceeds the standard.

[0007] S2. Temperature Array Online Measurement and Dual Verification Correction: A temperature monitoring array is arranged on the cross-section of the flue gas duct. The difference in thermal conductivity between fly ash and flue gas is used to determine the ash accumulation coverage area by measuring the temperature drop at the measuring point. The theoretical ash accumulation height calculated in S1 is corrected based on the temperature measurement data to obtain the actual ash accumulation height and perform dual verification judgment.

[0008] S3. Graded periodic inspection: Based on the actual ash accumulation judgment results output by S1 and S2, as well as the boiler's operating load, coal quality parameters and fan operating status, a four-level periodic inspection consisting of daily patrol inspection, daily spot inspection, shutdown inspection and special condition inspection is carried out, and the inspection frequency and inspection content are dynamically adjusted.

[0009] S4. Differentiated treatment hardware deployment by zone: Based on the location and ash accumulation characteristics of the flue gas duct, the flue gas duct is divided into the area of ​​the burner secondary air box and hot secondary air connecting duct, the denitrification flue and boiler main horizontal flue area, and the electrostatic precipitator inlet connecting flue area. Corresponding adjustable flow field adjustment structures and purging devices are deployed in each area.

[0010] S5, Active Ash Suppression under Working Conditions: The actual ash accumulation height, actual additional load, and real-time boiler operating parameters calculated or corrected by S1 and S2 are used as control trigger signals. When the signal meets the set conditions, the adjustable flow field adjustment structure and purging device in the corresponding area of ​​S4 are automatically linked to control the flue gas flow field structure, flue gas velocity, and purging frequency.

[0011] S6. Standardized confined space ash removal operation and ledger management: When the boiler is shut down, after confirming that the gas environment and isolation status in the flue meet the safety conditions, the excessive ash accumulation area is cleaned in sections, and a dynamic ash accumulation ledger is established to record the investigation data, ash accumulation parameters, rectification measures and treatment effects throughout the entire process. At the same time, the parameters corrected after ash removal are fed back to S1 to update the theoretical calculation model.

[0012] Furthermore, in step S1, the specific method for calculating and determining the theoretical ash accumulation height in different flue regions is as follows:

[0013] For the horizontal flue in front of the dust collector, the theoretical ash accumulation height Calculate using the following formula:

[0014] ;

[0015] In the above formula, This refers to the cross-sectional width of the flue, in meters. This refers to the cross-sectional height of the flue, in meters. This represents the percentage of the boiler's current operating load. The design flue gas flow rate through the flue under rated operating conditions, in units of... ;

[0016] The above formula simplifies to:

[0017] Equation (1)

[0018] This is a correction factor for flue gas flow characteristics, mainly related to fly ash particle size and critical carry-over velocity, with a value range of 6-10, preferably 8. It is used when the boiler's current operating load percentage... Flue gas design velocity At that time, the allowable ash accumulation height threshold is the height of the flue section. 34.37%;

[0019] When the boiler is currently operating at a certain percentage of load Flue gas design velocity At that time, and the ash accumulation height reaches the cross-sectional height of the flue. When the dust concentration reaches 62.5%, it is considered a high-risk state for dust accumulation.

[0020] For horizontal flues following the dust collector, if the flue is rectangular, the threshold for determining the allowable ash accumulation height is set to the cross-sectional height of the flue. of For circular pipes, the threshold for determining the allowable dust accumulation height is set to a percentage of the flow cross-sectional area. ;

[0021] For the horizontal connecting air duct and air box at the air preheater outlet, the allowable ash accumulation height threshold is set to a fixed value. ;

[0022] For inclined flue gas ducts, the theoretical ash accumulation height of the inclined flue gas duct Calculate using the following formula:

[0023] ;

[0024] In the above formula, The angle between the bottom surface of the flue and the horizontal plane, expressed in degrees. This represents the theoretical ash accumulation height of a horizontal flue of the same specifications, expressed in meters.

[0025] Furthermore, in step S1, the additional load of the accumulated ash... Calculate using the following formula:

[0026] ;

[0027] In the above formula, Additional load for ash accumulation, unit: , The height of the accumulated dust is taken as... or The unit is meters. This refers to the gravitational density of fly ash, in units of... Among them, the gravitational density of fly ash in the flue gas duct before desulfurization The value is based on dry ash, and the range is 8-10. Gravitational density of fly ash in flue gas duct after desulfurization The value is taken based on wet ash, and is set to 15. .

[0028] Furthermore, in step S2, the method for arranging a temperature monitoring array on the cross-section of the flue is as follows:

[0029] No fewer than 5 rows of temperature measuring points shall be arranged in the width direction of the flue section, and no fewer than 3 temperature measuring points shall be arranged in each row at different heights, with the temperature measuring points arranged from the bottom of the flue upwards; and a wear-resistant protective cover shall be installed on the windward side of the temperature measuring points.

[0030] Furthermore, in step S3, the four-level periodic investigation is as follows:

[0031] Routine inspection: Performed once per shift, used to monitor the air pressure, smoke temperature, and air volume of the flue, and to check the appearance of the flue body and supports for any deformation or leakage;

[0032] Routine inspection: Performed once a day, focusing on checking the condition of the horizontal section supports and hangers, and inspecting the flue shell and welds for cracks, displacement and deformation;

[0033] Shutdown inspection: Performed while the boiler is shut down, enter the flue gas duct to measure the thickness and extent of ash accumulation, calculate the total amount of ash accumulation, and check the condition of reinforcing ribs, welds, and expansion joints;

[0034] Special inspections for special operating conditions: When the ash content of the coal entering the furnace increases significantly, the boiler operates at low load for a long time, one-sided fan is running, or the S1 / S2 indicator determines that the ash accumulation is close to the threshold, the inspection frequency will be increased to once every 4 hours, with a focus on inspecting the horizontal sections and connecting air ducts that are prone to ash accumulation.

[0035] Further, in step S3, the partition differentiation governance is as follows:

[0036] For the burner secondary air box and hot secondary air connecting duct area, wear-resistant steel plates are used to completely seal the pit at the bottom of the air box to obtain a flat bottom surface, and a guide plate is installed at the duct inlet. A pneumatic turbulence device and a continuous purging pipeline are installed inside the duct.

[0037] For the denitrification flue and the main horizontal flue of the boiler, guide plates and perforated flow straightening plates are installed in the dead corners and diameter change sections of the flow field, and purging devices are installed in the sections where ash easily accumulates.

[0038] For the electrostatic precipitator inlet connecting flue area, a vertical perforated plate is installed in the ash accumulation area. The vertical perforated plate is connected to the top plate of the flue. The height of the vertical perforated plate is 2.1m and the opening rate is 50%. Air cannons are arranged in the ash accumulation area for directional purging.

[0039] Furthermore, in step S5, the condition-linked active dust suppression is as follows:

[0040] When the boiler is currently operating at 50% of its rated load, increase the guide angle of the guide plate and switch the purging device from timed purging mode to intermittent continuous purging mode.

[0041] When a single fan is running, shorten the purging interval of the corresponding purging device in the flue on the shut-off side.

[0042] When the positive pressure in the furnace increases, the frequency of inspections of the entire flue should be increased, and the frequency of purging of the purging device should be increased.

[0043] When the ash content of the coal entering the furnace increases, the purging intensity and inspection frequency of the purging device should be increased, and the theoretical ash accumulation height should be recalculated daily.

[0044] Furthermore, in step S6, the standardized confined space cleaning operation process is as follows:

[0045] P1. Environmental and Safety Monitoring: The monitoring measures the oxygen content and concentration of toxic and harmful gases inside the flue to ensure they meet the preset safety thresholds, and the controlled equipment cuts off the power and triggers an isolation lockout signal.

[0046] P2. Isolation and sealing: Shut down the dust and smoke ventilation system to be cleaned, cut off the power source and lock it with tags, and isolate the upstream and downstream equipment;

[0047] P3. Segmented dust removal: Remove accumulated dust in segments, from the outside in and from top to bottom.

[0048] P4. Completion and Acceptance: After the dust removal is completed, the thickness of the residual dust is measured. Once it is confirmed that the standard is met, the isolation is lifted, and the dust removal data and measured parameters are synchronized to the ledger management database to update the calculation correction coefficient in step S1.

[0049] This invention also discloses a boiler flue gas duct ash accumulation collaborative control system based on deep peak shaving conditions, used to implement the above method, including:

[0050] The parameter acquisition unit is used to collect boiler operating load, flue gas flow, flue size, fan current, fan output, fan vibration, air pressure, flue gas temperature, furnace pressure, and coal quality parameters in real time.

[0051] The quantization calculation module is used to calculate the theoretical dust accumulation height based on the collected parameters. Theoretical ash accumulation height of inclined flue and additional load from ash accumulation ;

[0052] A temperature monitoring array is arranged on the cross-section of the flue gas duct to measure the distribution and actual height of ash accumulation inside the flue gas duct online and to correct the calculation results of the quantification module.

[0053] The hierarchical decision-making module is used to dynamically generate four-level periodic inspection instructions based on the boiler's operating status and issue an early warning when it is determined that the ash accumulation exceeds the standard.

[0054] The working condition linkage actuator includes an adjustable angle guide vane, an air cannon, a continuous purging pipeline, and a pneumatic turbulence device, which are used to perform flow field adjustment and purging operations;

[0055] The ledger management database is used to record the investigation time, flue location, boiler load, theoretical ash accumulation height, actual ash accumulation height, and additional ash accumulation load. Record and analyze the governance measures and the completion status of rectification.

[0056] Compared with the prior art, the present invention has the following advantages:

[0057] 1. Precise judgment and quantitative control: Through a specific mathematical model, the ash accumulation height and load are fully calculated quantitatively, replacing the traditional manual experience judgment and avoiding omissions and misjudgments;

[0058] 2. Scientific inspection system: It adopts a four-level hierarchical periodic inspection mode, which can dynamically adjust the inspection frequency according to the boiler operating conditions to ensure that hidden dangers under high-risk conditions are detected and dealt with early.

[0059] 3. Highly targeted treatment: Based on the type of flue and air duct and the characteristics of ash accumulation, zoned measures are implemented, dividing the flue and air duct into two major areas, with ash suppression and ash removal methods highly matched;

[0060] 4. High adaptability to operating conditions: A linkage mechanism between load, fan and coal quality has been established to actively suppress ash accumulation under conditions such as low load peak shaving, thereby reducing fly ash deposition from the source;

[0061] 5. Logical closed loop and safety controllability: A technical closed loop of "perception-decision-execution-feedback" has been constructed, which not only standardizes the dust removal process to reduce safety risks, but also feeds back the calculation model through ledger feedback, realizing continuous optimization of dust accumulation management. Attached Figure Description

[0062] Figure 1 This is a flowchart illustrating the method of the present invention.

[0063] Figure 2 This is a schematic diagram of the arrangement of the temperature monitoring array on the cross-section of the flue gas duct in Example 2. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0065] Example 1

[0066] This embodiment provides a collaborative control system for ash accumulation in boiler flue gas ducts based on deep peak-shaving conditions. The system specifically includes:

[0067] Parameter acquisition unit: Composed of sensors distributed throughout the boiler and a DCS system communication interface, used to acquire in real time the boiler's current operating load percentage (%) and design flue gas flow rate (%). ), current and output of induced draft fan / forced draft fan / primary air fan, fan vibration frequency, air pressure in each section of flue gas duct, flue gas temperature, furnace pressure and coal quality parameters fed into the furnace;

[0068] Quantitative Calculation Module: This is a software algorithm unit deployed in the industrial control computer. Its input is connected to the parameter acquisition unit. It integrates mathematical calculation models for horizontal flues, inclined flues, and ash accumulation loads, and is used to output the theoretical ash accumulation height of horizontal flues in real time. Theoretical ash accumulation height of inclined flue and additional load from ash accumulation ;

[0069] Temperature monitoring array: such as Figure 2 As shown, the test points are arranged on the test section of a flue gas duct prone to dust accumulation. In this embodiment, five rows of temperature measuring points are arranged at equal intervals along the width of the flue gas duct, and three armored thermocouple measuring points are arranged from bottom to top along the height of each row (a total of 15 measuring points, numbered from measuring point T1-1 to measuring point T5-3). Each thermocouple has a wear-resistant steel anti-wear protective cover welded to its windward side. The millivolt signal of the thermocouple is connected to the data acquisition card through a compensation wire and transmitted to the quantization calculation module, which is used to measure the dust accumulation boundary online and correct the theoretical calculation value based on the sudden drop in local temperature caused by fly ash (extremely low thermal conductivity) coverage.

[0070] The graded decision-making module connects to the quantitative calculation module at its input end to receive the corrected actual ash accumulation height and load. This module has a dual-verification algorithm and, when it determines that the actual ash accumulation height or load is close to the design allowable limit, sends multi-level early warning signals to operators via the control bus. Simultaneously, it dynamically generates four-level periodic inspection instructions based on the boiler's operating conditions.

[0071] Working condition linkage actuator: Its control end is connected to the output end of the hierarchical decision module. The physical terminal includes: an adjustable angle guide plate (driven to rotate by a servo motor) fixedly installed on the inner side wall of each flue inlet pipe by welding, an air cannon group controlled by electromagnetic pulse, and a pneumatic turbulence device (equipped with a compressed air pipeline and a swirling nozzle with a pneumatic regulating valve) fixed inside the air box by pipe clamps.

[0072] Ledger Management Database: Utilizes an SQL database server, with bidirectional data connections to the hierarchical decision-making module and the quantitative calculation module. It automatically records investigation time, flue location, boiler load, theoretical ash accumulation height, measured ash accumulation height, and additional ash accumulation load. The report details the governance measures taken and the completion status of rectification, and regularly generates ash accumulation trend analysis reports.

[0073] Example 2

[0074] like Figure 1 As shown, this embodiment is based on the system usage method in Embodiment 1, and applies this method to a 1000MW and 660MW unit in a power plant. The boiler is a π-type boiler manufactured by Dongfang Boiler Factory, and the burners are front and rear wall opposed burners. Three layers of pulverized coal burner air chambers and two layers of burnout air chambers are symmetrically arranged on the front and rear walls. The air box itself weighs approximately 605 tons. On-site inspection showed an average ash accumulation thickness of 1.0 meter in a single air chamber, and the estimated total ash weight of the five air chambers was 340 tons. The 22 constant force springs suspending the air box have a maximum load capacity of approximately 1009 tons. After ash accumulation, the total weight of the air box reaches 945 tons, and the air box hanger loses its safety margin, posing a serious risk of overload and collapse. This embodiment verifies its convertible value under actual working conditions. This embodiment details the data flow and control flow transmission process of "perception-decision-execution-feedback" between steps S1 to S6:

[0075] S1. Ash accumulation quantification calculation and exceeding standard judgment

[0076] This step involves classifying, quantifying, and determining the flue gas ducts in different areas:

[0077] S101, Horizontal flue before dust collector (1000MW unit):

[0078] The cross-sectional width of the horizontal flue at the inlet of the secondary air box is known. Cross-section height Design flue gas velocity .

[0079] When the boiler is at its minimum stable combustion load At this time, the load is in the preset low load range (usually set at 30%-50%). Under this load range, the flue gas velocity decreases, and the fly ash carrying capacity begins to decline significantly. This is the critical start-up stage for ash accumulation monitoring. At this time, the design flue gas velocity... Within the preset flow rate range (usually Substitute into equation (1) to calculate the allowable dust accumulation height:

[0080]

[0081] according to Total height of flue m can be obtained as follows:

[0082] =34.37% (rounded to two decimal places).

[0083] Received 34.37% falls within the preset first proportion range (usually set to 30%-40%). This first proportion range is set based on engineering experience regarding the safety redundancy of the flue structure and the prevention of a sharp increase in local resistance of the flue gas. Setting a threshold within this range can ensure that the flue does not become severely blocked and can effectively avoid frequent false alarms caused by fluctuations in a small amount of ash accumulation.

[0084] It should be noted that the allowable ash accumulation height as a percentage of the total flue height is not fixed, but rather depends on the boiler's current operating load percentage. (Typically fluctuating between 30% and 100%), design flow rate (usually in 12) -18 The ash accumulation height varies dynamically depending on the characteristics of the coal and fly ash. Therefore, in practical engineering applications, the allowable ash accumulation height to account for the total height of the flue is usually set between 25% and 45%, with a preferred range of 30% to 40%. The 34.37% obtained above is a typical preferred implementation value of this invention under specific low-load conditions of a 1000MW unit. Any threshold setting within this range can effectively meet the dual requirements of "avoiding flue blockage" and "preventing frequent false alarms".

[0085] When the generating unit enters deep peak-shaving operation, the load drops to... (That is, when the preset extremely low load threshold is reached, usually set in the range of 15%-25%, at which point the flue gas velocity is extremely low and the fly ash deposition rate increases exponentially), substitute the values ​​into the formula to calculate the theoretical ash accumulation height under low load:

[0086]

[0087] At this point, the theoretical ash accumulation height accounts for 62.5% of the total height of the flue (which has reached the preset second proportion threshold, usually set between 55% and 70%), which is 28.13% higher than the design allowable value. When the proportion of ash accumulation height reaches this threshold, it indicates that the effective flow cross-sectional area of ​​the flue has been drastically reduced, and the ash accumulation load is about to exceed the structural safety limit. Based on this, the system determines that it has entered a "high-risk state of ash accumulation".

[0088] This section of the flue is located before desulfurization; the fly ash density is taken as the dry ash value. Substitute the values ​​into the formula to calculate the additional ash accumulation load:

[0089]

[0090] Since the average dust accumulation thickness of a single-layer air chamber is 1.0 meter, the total weight of dust accumulation in the 5-layer air chamber is estimated to be 340 tons, and the weight of the air box itself is about 605 tons. At this time, the total weight of the air box and dust accumulation reaches 605 + 340 = 945 tons, which is close to the maximum load of 1009 tons of the 22 constant force springs that lift the air box. The graded decision module immediately judges it to be in a "high-risk dust accumulation state" and issues an over-limit warning.

[0091] S102, Horizontal flue after dust collector (660MW unit):

[0092] The cross-sectional width of the horizontal flue of this connecting flue section Cross-section height Its design allows the ash accumulation height threshold to be set to the height of the flue. :

[0093]

[0094] The measured maximum dust accumulation height has reached (Exceeding 1 / 2 the height of the flue) is considered a serious violation;

[0095] This section of the flue is located before desulfurization; the dry ash gravity density is taken as... Substitute the values ​​into the formula to calculate the local additional load:

[0096]

[0097] The total amount of dust in the local area reached It was determined that there was a risk of tearing of the flue shell and deformation of the supports.

[0098] S103, Calculation for correction of inclined flue gas duct:

[0099] If there is an angle between the bottom surface of the flue gas duct and the horizontal plane in the aforementioned 1000MW unit For the inclined flue gas duct, substitute the values ​​into the formula to calculate the angle correction:

[0100] The theoretical ash accumulation height of horizontal flues of the same specifications is known. The theoretical ash accumulation height of the inclined flue is:

[0101]

[0102] The corresponding additional ash accumulation load is corrected as follows:

[0103]

[0104] This step changes the traditional method of estimating ash accumulation based solely on human observation and experience. It achieves precise quantitative calculation of ash accumulation height and load through a specific physical and mathematical model, providing scientific and accurate data support for subsequent active ash suppression and cleaning decisions.

[0105] S104, Horizontal connecting air duct and air box at the air preheater outlet:

[0106] For the horizontal connecting air duct and air box at the outlet of the air preheater, due to the extremely complex internal flow field, multiple diameter changes, and the high likelihood of severe local dust accumulation, it is not possible to use a uniform cross-sectional ratio for dynamic judgment. Instead, the threshold for judging the allowable dust accumulation height is set to a preset fixed height value.

[0107] In this embodiment, the preset fixed height value is specifically set to a fixed value of 0.3m (usually selected between 0.2m and 0.4m based on the air preheater outlet flow channel height, flue gas resistance sensitivity, and the effective range of the purging device). When the system detects online through the temperature monitoring array or manually that the actual ash accumulation height in the area reaches or exceeds 0.3m, the graded decision module immediately determines that the ash accumulation exceeds the standard and triggers the operating condition linkage actuator to perform directional purging or issue a dust removal warning.

[0108] This step changes the traditional method of estimating ash accumulation based solely on human observation and experience. It achieves precise quantitative calculation of ash accumulation height and load through a specific physical and mathematical model, providing scientific and accurate data support for subsequent active ash suppression and cleaning decisions.

[0109] S2, Online Temperature Array Measurement and Dual Verification Correction

[0110] Array arrangement: Arranged on the cross-section of the 1000MW unit wind box and the 660MW connecting flue as follows Figure 2 The temperature monitoring array shown (5 columns in width, 3 rows in height, with anti-wear protective covers on the windward side of the thermocouples);

[0111] Measurement and Dual Verification: During the operation of the 660MW unit, the system monitored that the temperature of four of the five measuring points at the bottom of the No. 2-3 connecting compartment dropped sharply from the normal 110℃ to 45℃. Based on the significant difference in thermal conductivity between fly ash and flue gas, it was determined that the area was covered by ash accumulation, and the actual ash accumulation height exceeded 1.0m (middle layer height). The final determination of the actual ash accumulation height was 1.5m. The theoretical calculation value of S1 was double-verified and corrected by the actual temperature measurement data.

[0112] This step enables non-contact, online, and real-time determination of dust accumulation height and distribution range, avoiding missed judgments due to theoretical calculation deviations and improving the accuracy of safety warnings.

[0113] It should be noted that the specific method of dual verification and correction is as follows: when the temperature measured by a temperature measuring point at a certain height level in the temperature monitoring array is lower than the preset temperature threshold, it is determined that the height level has been covered by fly ash, and the coverage height is used as the measured ash accumulation height; the measured ash accumulation height is compared with the theoretical ash accumulation height calculated in S1: if the deviation between the two is greater than the preset deviation ratio, the measured ash accumulation height is used to replace the theoretical ash accumulation height in the subsequent judgment, and the flow characteristic correction coefficient in formula (1) is corrected in reverse according to the deviation value. .

[0114] S3, tiered periodic screening

[0115] Based on the unit's operating status and the accurate ash accumulation parameters output by S1 / S2, a four-level periodic inspection is dynamically performed:

[0116] Routine inspection: Performed once per shift (8 hours), monitoring the wind pressure, flue gas temperature, and air volume of the 1000MW unit, and inspecting the appearance of the wind box body and supports;

[0117] Routine inspection: Performed once a day, with a focus on checking the condition of the horizontal section of the 660MW connecting flue and inspecting for cracks in the outer shell welds;

[0118] Shutdown inspection: With the 660MW unit shut down, an on-site measurement was conducted in the connecting flue, and it was found that the connection areas of compartments 2-3, 4-5, and 6-7 were severely dusty, with the maximum dust accumulation height exceeding the standard.

[0119] Special investigation for special operating conditions: Triggered when the ash content of the coal fed into the furnace of the 660MW unit suddenly increases from 15% to 28%, or when the actual additional load calculated by S1 / S2 is applied. When the threshold of safety is reached to 80%, the system will automatically trigger an alarm, and the frequency of checks will be automatically increased from once a day to once every 4 hours.

[0120] This step, through a tiered and condition-triggered mechanism, concentrates inspection efforts on high-risk periods and areas, increasing the timeliness of hazard detection by over 90%.

[0121] S4, hardware deployment for zone-specific governance

[0122] Based on the location and dust accumulation characteristics of the flue gas duct, the flue gas duct was divided into two main areas and the hardware installation was completed:

[0123] S401, Burner Secondary Air Box and Hot Secondary Air Connecting Duct Area (1000MW Unit - Zone 1):

[0124] Structural connection description: The recessed structure at the bottom of the wind box is fully covered with a 10mm thick wear-resistant steel plate and fully welded to the bottom plate of the wind box around the perimeter, so that the bottom of the wind box forms a completely flat bottom surface; Three sets of carbon steel guide plates are fixedly welded to the inner wall of the wind box inlet pipe by full welding, and the three sets of guide plates are arranged in parallel with equal spacing.

[0125] Description of the turbulence device connection: The pneumatic turbulence main pipe is horizontally fixed inside the wind box by bolts and stainless steel pipe clamps. Multiple vertically downward swirling nozzles are threaded at equal intervals on the main pipe. The nozzle outlets face the bottom of the wind box, and the nozzles are equipped with 45° guide swirling blades inside.

[0126] S402, Electrostatic Precipitator Inlet Connecting Flue Area (660MW Unit - Second Zone):

[0127] A steel vertical perforated plate with a thickness of 8mm is installed in the connecting flue of compartments 2-3 and 6-7. The upper end of the vertical perforated plate is fully welded to the top plate of the flue, and the two sides are fully welded to the side wall plates of the flue. The height of the perforated plate is designed to be 2.1m (accounting for 70% of the height of the flue), and the opening ratio is set to 50%.

[0128] An opening is made in the outer wall of the connecting flue, and two air cannons are sealed and fixedly installed on the outer wall of the flue using flange bolts and sealing gaskets. The nozzles of the air cannons extend into the flue through the outer wall openings, and the nozzle outlet is fixed at 50mm from the bottom of the flue. The nozzles of the two air cannons are arranged in a staggered manner facing each other in the horizontal width direction, and their axial spacing is fixed at 2376mm.

[0129] This step ensures that the thickness of ash accumulation inside the bellows remains below 30cm for an extended period, restores the load of the constant force spring hanger to a safe range, and eliminates the risk of collapse. The amount of ash accumulation in the connecting flue is reduced by approximately 80%, eliminating the potential for flue deformation and cracking.

[0130] S5, Active Dust Suppression Based on Operating Conditions

[0131] Based on the boiler's real-time operating conditions and the real-time ash accumulation data fed back by S1 / S2, the flow field and purging are dynamically adjusted:

[0132] Deep peak shaving operation linkage: When the load of a 1000MW unit is lower than 50% of the rated load, the DCS system will automatically increase the angle of the adjustable guide vane from 15° to 35°, and simultaneously switch the aerodynamic turbulence device from "timed purging every 8 hours" to "intermittent continuous purging every 30 minutes", maintaining the purging pressure at... ;

[0133] Single-sided fan operation linkage: When a single-sided induced draft fan of the 660MW unit is shut down for maintenance, the system automatically links to shorten the air cannon purging interval of the shut-down side and the connecting flue from once every 2 hours to once every 30 minutes, forcibly disturbing the dead corners where dust easily accumulates.

[0134] This step actively increases the local flue gas velocity and purging frequency under extreme working conditions where dust easily accumulates, thereby suppressing fly ash settling at the source and transforming passive dust removal into active dust suppression.

[0135] S6. Standardized confined space cleaning operations and record management

[0136] P1. Environmental and Safety Testing: The oxygen volume percentage inside the air box and flue is 20.3% (between 19.5% and 21%), the oxygen concentration is 8 ppm, the toxic gas concentration meets the standards, and the controlled fan is powered off and locked with a tag.

[0137] P2. Isolation and sealing: Shut down the corresponding side flue gas system, cut off the power source of the induced draft fan and lock it with a tag, and install a physical isolation plug;

[0138] P3. Segmented dust removal: Dust removal personnel wear dust masks and perform segmented dust removal in the order of "from the outside to the inside and from the top to the bottom" to avoid large-scale dust accumulation and collapse.

[0139] P4. Completion Acceptance and Data Closure: After cleaning, the actual measured thickness of residual ash is 0m. The isolation is lifted and the operation is cancelled.

[0140] The system can input the investigation time, 1000MW load, theoretical value (5.0m), measured value (1.0m), treatment measures, and dust removal effect into the ledger management database as needed, and generate monthly trend analysis reports. The ledger database feeds back the measured deviation to the S1 calculation module, which then adjusts the flow characteristic correction coefficient. The value is fine-tuned and optimized to complete the entire process of technical closed loop.

[0141] The above measures ensured personal safety throughout the entire dust removal process and enabled closed-loop management and long-term governance of ash accumulation data.

[0142] It should be noted that the structure described in this invention can be implemented in many different forms and is not limited to the embodiments described. Any equivalent transformations made by those skilled in the art based on the description and drawings of this invention, or direct or indirect applications in other related technical fields, such as the loading and unloading of other items, are included within the protection scope of this invention.

Claims

1. A method for coordinated control of ash accumulation in boiler flue gas ducts based on deep peak-shaving conditions, characterized in that, Includes the following steps: S1. Ash Accumulation Quantification and Exceedance Judgment: Real-time acquisition of boiler operating parameters and flue gas duct dimensions to calculate the theoretical ash accumulation height and additional ash accumulation load in different flue gas duct areas. The calculation results are compared with the set threshold for exceeding the standard to determine whether the dust accumulation exceeds the standard. S2. Temperature Array Online Measurement and Dual Verification Correction: A temperature monitoring array is arranged on the cross-section of the flue gas duct. The difference in thermal conductivity between fly ash and flue gas is used to determine the ash accumulation coverage area by measuring the temperature drop at the measuring point. The theoretical ash accumulation height calculated in S1 is corrected based on the temperature measurement data to obtain the actual ash accumulation height and perform dual verification judgment. S3. Graded periodic inspection: Based on the actual ash accumulation judgment results output by S1 and S2, as well as the boiler's operating load, coal quality parameters and fan operating status, a four-level periodic inspection consisting of daily patrol inspection, daily spot inspection, shutdown inspection and special condition inspection is carried out, and the inspection frequency and inspection content are dynamically adjusted. S4. Differentiated treatment hardware deployment by zone: Based on the location and ash accumulation characteristics of the flue gas duct, the flue gas duct is divided into the area of ​​the burner secondary air box and hot secondary air connecting duct, the denitrification flue and boiler main horizontal flue area, and the electrostatic precipitator inlet connecting flue area. Corresponding adjustable flow field adjustment structures and purging devices are deployed in each area. S5, Active Ash Suppression under Working Conditions: The actual ash accumulation height, actual additional load, and real-time boiler operating parameters calculated or corrected by S1 and S2 are used as control trigger signals. When the signal meets the set conditions, the adjustable flow field adjustment structure and purging device in the corresponding area of ​​S4 are automatically linked to control the flue gas flow field structure, flue gas velocity, and purging frequency. S6. Standardized confined space ash removal operation and ledger management: When the boiler is shut down, after confirming that the gas environment and isolation status in the flue meet the safety conditions, the excessive ash accumulation area is cleaned in sections, and a dynamic ash accumulation ledger is established to record the investigation data, ash accumulation parameters, rectification measures and treatment effects throughout the entire process. At the same time, the parameters corrected after ash removal are fed back to S1 to update the theoretical calculation model.

2. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 1, characterized in that: In step S1, the specific methods for calculating and determining the theoretical ash accumulation height in different flue regions are as follows: The theoretical ash accumulation height of the horizontal flue before the dust collector Calculate using the following formula: ； In the above formula, This refers to the cross-sectional width of the flue, in meters. This refers to the cross-sectional height of the flue, in meters. This represents the percentage of the boiler's current operating load. The design flue gas flow rate through the flue under rated operating conditions is expressed in units of [missing information]. ; The above formula simplifies to: ； In the above formula, This is a correction factor for flue gas flow characteristics. Design flue gas velocity and design flue gas flow rate The following conditions must be met: ; When the boiler is currently operating at a certain percentage of load Within the preset low load range, and with the designed flue gas flow rate When the flow rate is within the preset range, the allowable ash accumulation height threshold is the height of the flue section. Within the first proportional range; When the boiler is currently operating at a certain percentage of load The preset extremely low load range is used, and the ash accumulation height reaches the height of the flue section. When the second proportional threshold is reached, it is determined to be a high-risk state of dust accumulation; For horizontal flues following the dust collector, if the flue is rectangular, the threshold for determining the allowable ash accumulation height is set to the cross-sectional height of the flue. of For circular pipes, the threshold for determining the allowable dust accumulation height is set to a percentage of the flow cross-sectional area. ; For the horizontal connecting air duct and air box at the air preheater outlet, the allowable dust accumulation height judgment threshold is set to a preset fixed height value. For inclined flue gas ducts, the theoretical ash accumulation height of the inclined flue gas duct Calculate using the following formula: ； In the above formula, The angle between the bottom surface of the flue and the horizontal plane, expressed in degrees. This represents the theoretical ash accumulation height in a horizontal flue, expressed in meters.

3. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 2, characterized in that: In step S1, the additional load of the ash accumulation Calculate using the following formula: ； In the above formula, Additional load for ash accumulation, unit: , The height of the accumulated dust is taken as... or The unit is meters. This refers to the gravitational density of fly ash, in units of... Among them, the gravitational density of fly ash in the flue gas duct before desulfurization The value is based on dry ash, and the range is 8-10. Gravitational density of fly ash in flue gas duct after desulfurization The value is taken based on wet ash, and is set to 15. .

4. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 1, characterized in that: In step S2, the method for arranging a temperature monitoring array on the cross-section of the flue is as follows: No fewer than 5 rows of temperature measuring points shall be arranged in the width direction of the flue section, and no fewer than 3 temperature measuring points shall be arranged in each row at different heights, with the temperature measuring points arranged from the bottom of the flue upwards; and a wear-resistant protective cover shall be installed on the windward side of the temperature measuring points.

5. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 1, characterized in that: In step S3, the four-level periodic investigation is as follows: Routine inspection: Performed once per shift, used to monitor the air pressure, smoke temperature, and air volume of the flue, and to check the appearance of the flue body and supports for any deformation or leakage; Routine inspection: Performed once a day, focusing on checking the condition of the horizontal section supports and hangers, and inspecting the flue shell and welds for cracks, displacement and deformation; Shutdown inspection: Performed while the boiler is shut down, enter the flue gas duct to measure the thickness and extent of ash accumulation, calculate the total amount of ash accumulation, and check the condition of reinforcing ribs, welds, and expansion joints; Special inspections for special operating conditions: When the ash content of the coal entering the furnace increases significantly, the boiler operates at low load for a long time, one-sided fan is running, or the S1 / S2 indicator determines that the ash accumulation is close to the threshold, the inspection frequency will be increased to once every 4 hours, with a focus on inspecting the horizontal sections and connecting air ducts that are prone to ash accumulation.

6. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 1, characterized in that: In step S3, the hardware deployment for the partition-based differentiated governance is as follows: For the burner secondary air box and hot secondary air connecting duct area, wear-resistant steel plates are used to completely seal the pit at the bottom of the air box to obtain a flat bottom surface, and an adjustable angle guide plate is installed at the duct inlet. A pneumatic turbulence device and a continuous purging pipeline are installed inside the duct. For the denitrification flue and the main horizontal flue of the boiler, guide plates and perforated flow straightening plates are installed in the dead corners and diameter change sections of the flow field, and purging devices are installed in the sections where ash easily accumulates. For the electrostatic precipitator inlet connecting flue area, a vertical perforated plate is installed in the ash accumulation area. The vertical perforated plate is connected to the top plate of the flue. The height of the vertical perforated plate is 2.1m and the opening rate is 50%. Air cannons are arranged in the ash accumulation area for directional purging.

7. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 1, characterized in that: In step S5, the active dust suppression mechanism linked to the operating conditions is as follows: When the boiler is currently operating at 50% of its rated load, increase the guide angle of the guide plate and switch the purging device from timed purging mode to intermittent continuous purging mode. When a single fan is running, shorten the purging interval of the corresponding purging device in the flue on the shut-off side. When the positive pressure in the furnace increases, the frequency of inspections of the entire flue should be increased, and the frequency of purging of the purging device should be increased. When the ash content of the coal entering the furnace increases, the purging intensity and inspection frequency of the purging device should be increased, and the theoretical ash accumulation height should be recalculated daily.

8. The method for coordinated control of boiler flue gas duct ash accumulation based on deep peak-shaving conditions as described in claim 1, characterized in that: In step S6, the standardized confined space cleaning operation process is as follows: P1. Environmental and Safety Monitoring: The monitoring measures the oxygen content and concentration of toxic and harmful gases inside the flue to ensure they meet the preset safety thresholds, and the controlled equipment cuts off the power and triggers an isolation lockout signal. P2. Isolation and sealing: Shut down the dust and smoke ventilation system to be cleaned, cut off the power source and lock it with tags, and isolate the upstream and downstream equipment; P3. Segmented dust removal: Remove accumulated dust in segments, from the outside in and from top to bottom. P4. Completion and Acceptance: After the dust removal is completed, the thickness of the residual dust is measured. Once it is confirmed that the standard is met, the isolation is lifted, and the dust removal data and measured parameters are synchronized to the ledger management database to update the calculation correction coefficient in step S1.

9. A boiler flue gas duct ash accumulation collaborative control system based on deep peak-shaving conditions, used to implement the method described in any one of claims 1 to 8, characterized in that, include: The parameter acquisition unit is used to collect boiler operating load, flue gas flow, flue size, fan current, fan output, fan vibration, air pressure, flue gas temperature, furnace pressure, and coal quality parameters in real time. The quantization calculation module is used to calculate the theoretical dust accumulation height based on the collected parameters. Theoretical ash accumulation height of inclined flue and additional load from ash accumulation ; A temperature monitoring array is arranged on the cross-section of the flue gas duct to measure the distribution and actual height of ash accumulation inside the flue gas duct online and to correct the calculation results of the quantification module. The hierarchical decision-making module is used to dynamically generate four-level periodic inspection instructions based on the boiler operating status and the correction results of the quantitative calculation module and the temperature monitoring array, and to issue an early warning when it is determined that the ash accumulation exceeds the standard. The working condition linkage actuator includes an adjustable angle guide vane, an air cannon, a continuous purging pipeline, and a pneumatic turbulence device. Its control terminal is connected to the hierarchical decision module to receive linkage control commands and execute flow field adjustment and purging operations. The ledger management database is used to record the investigation time, flue location, boiler load, theoretical ash accumulation height, actual ash accumulation height, and additional ash accumulation load. Record and analyze the governance measures and rectification completion status, and connect the data with the quantitative calculation module to update the algorithm parameters.

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