Ammonia bisulfate blockage control method for air pre-heater of high-sulfur coal blending combustion boiler

Abstract

The invention relates to the technical field of comprehensive treatment of ammonium bisulfate blockage of an air pre-heater when a coal-fired boiler is mixed with high-sulfur fuel, in particular to an ammonium bisulfate blockage control method for an air pre-heater of a boiler mixed with high-sulfur coal. Comprising the following steps: collecting flue gas components, wall surface temperature distribution and differential pressure gradient data through a flue gas analyzer, an optical fiber temperature sensor array and a differential pressure transmitter; the control platform integrates the coal sulfur content parameters to calculate a transient dew point temperature field, and high-risk area coordinates and a temperature deviation value are output through spatial overlay analysis; the closed circulation heat recovery system drives heat medium water partition flow distribution according to the high-risk coordinates, and an axial air heater executes gradient heating to enable the wall temperature of a high-risk area to be continuously higher than a dew point temperature set value; and when the differential pressure exceeds the limit, high-risk area heating medium flow increasing, ammonia spraying amount restraining and sound wave directional clearing operation are synchronously triggered. And through multi-stage data closed-loop cooperation, the problems of air pre-heater blockage and boiler output limitation caused by ammonium bisulfate deposition are solved.

Description

Technical Field

[0001] This invention relates to the field of comprehensive treatment of ammonium bisulfate blockage in air preheaters of coal-fired boilers that are co-fired with high-sulfur fuels, and particularly to a method for controlling ammonium bisulfate blockage in air preheaters of boilers that are co-fired with high-sulfur coals. Background Technology

[0002] When boilers are operated with high-sulfur coal, the concentration of sulfur oxides in the flue gas increases. Ammonia injected into the selective catalytic reduction denitrification unit reacts with sulfur oxides in the flue gas to generate ammonium bisulfate. When the temperature of the cold section of the air preheater is lower than the dew point of ammonium bisulfate, the compound condenses and deposits on the surface of the heat transfer elements. The viscous deposits gradually accumulate and solidify to form blockages, hindering the flow path of flue gas and air, thereby reducing heat exchange efficiency, increasing system resistance, and ultimately leading to unstable operation and maintenance burden.

[0003] In the process of improving the economic efficiency of coal-fired power units by blending high-sulfur coal, a key challenge lies in the blockage at the cold end of the air preheater induced by ammonium bisulfate adhesion, which forcibly limits boiler output. The blockage formation process involves the reaction of increased sulfur oxides in the flue gas with excess ammonia from denitrification to produce ammonium bisulfate. When this ammonium bisulfate flows with the flue gas to the low-temperature region at the cold end of the air preheater, it condenses and deposits. The deposits accumulate and harden, significantly reducing the effective flow area of ​​the channel, leading to increased flue gas flow resistance and exhaust temperature, a sharp increase in induced draft fan power consumption, and a deterioration in heat transfer efficiency. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for controlling ammonium bisulfate blockage in the air preheater of a boiler that co-fires high-sulfur coal, thereby solving the problem of ammonium bisulfate adhesion inducing cold-end blockage of the air preheater and limiting boiler output during the co-firing of high-sulfur coal.

[0005] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows: The present invention provides a method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal, comprising: Step 1: A laser in-situ flue gas analyzer deployed at the tail flue of the boiler collects flue gas composition data; a distributed fiber optic temperature sensor installed at the cold end of the air preheater collects wall temperature distribution data; and a triple redundant differential pressure transmitter on the flue gas side of the air preheater collects differential pressure gradient data. Step 2: The control platform acquires the flue gas composition data from Step 1 and the real-time sulfur parameters of the online coal quality analysis system, and calculates the transient dew point temperature field of ammonium bisulfate; it performs spatial superposition analysis on the wall temperature distribution data from Step 1 and the calculated transient dew point temperature field, and outputs the coordinates of high-risk areas and the temperature deviation. Step 3: The closed-loop heat recovery system receives the coordinates and temperature deviation of the high-risk area from Step 2 and controls the branch flow regulating valve of the heat medium water to perform zoned flow distribution; the axial air heater uses zoned flow to heat and deliver air, so that the cold end wall temperature of the high-risk area is higher than the dew point temperature set value of the area output in Step 2. Step 4: When the differential pressure gradient data in Step 1 exceeds the set threshold, increase the flow rate of the heat transfer medium in the high-risk area to the preset upper limit value, and send an instruction to limit the amount of ammonia injected for denitrification to 1.04-1.07 times the theoretical requirement. Locate the coordinates of the high-risk area in Step 2 and perform sonic purging.

[0006] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: In step 1, the distributed fiber optic temperature sensor collects axial and radial temperature data in a 40-point temperature measurement array divided into 10° sectors. In step 2, the ammonium bisulfate formation rate model is updated based on real-time sulfur parameters. Deviation analysis is performed on the temperature distribution data and transient dew point temperature field in step 1, and areas with deviations > 3℃ are marked as over-limit areas. The control platform outputs the coordinates of the over-limit area to the branch flow regulating valve positioning operation in step 3, which is used to guide the distribution of heat medium water flow in high-risk areas.

[0007] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: In step 3, the closed-loop heat recovery system receives the coordinates of the over-limit area and the temperature deviation from step 2, and generates a flow distribution command using a fuzzy proportional integral differential algorithm; the command drives the electric regulating valve group to adjust the flow rate of the heat medium water, so that the primary air heater and the secondary air heater are distributed according to a preset ratio. When a marked over-limit area is identified, the flow rate of the heat medium water in the branch corresponding to the marked over-limit area is increased, while the allocation weight of non-key areas is reduced.

[0008] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: The axial heater receives the hot water flow rate allocated in step 3 according to the zone and performs gradient heating and air supply operation. Based on the difference between the transient dew point temperature output in step 2 and the measured wall temperature, dynamically adjust the target values ​​for air temperature control in each zone. The rate of temperature change during the heating process is limited to a set safety threshold.

[0009] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention... Step 4 also includes: Increase the flow rate of the heat transfer medium in the secondary air heater to the maximum design value; Send an ammonia reduction command to the denitrification system to limit the ammonia injection rate to 1.04 to 1.07 times the theoretical requirement; Based on the coordinates of the high-risk area in step 2, drive the acoustic soot blower to perform a targeted cleaning operation.

[0010] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: Limiting the amount of ammonia injected during denitrification operations will constrain the actual amount of ammonia injected to between 1.04 and 1.07 times the theoretical requirement. When the acoustic soot blower performs a fixed-point cleaning operation, it generates a modulated pulse sound field based on the high-risk coordinates in step 2.

[0011] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: Adjust the opening of the low-temperature economizer bypass valve according to the wall temperature safety status in step 3, so that the flue gas temperature is stabilized in the safe range above the acid dew point. By comparing the required heat load of the heater with the amount of waste heat produced, when there is excess waste heat, the excess heat is introduced into the low-pressure heater system.

[0012] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: Based on the comparison between the heat load demanded by the heater and the waste heat output, a waste heat dispatching command is output to control the execution of the three-way switching valve; The flue gas temperature adjustment amount is dynamically corrected based on the transient dew point temperature prediction value from step 2.

[0013] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: The wall temperature safety data and turbine extraction parameters obtained during step 4 are fed back into the ammonium bisulfate formation prediction model in step 2. The prediction model updates the calculation parameters by executing a rolling optimization algorithm based on the feedback parameters.

[0014] Furthermore, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention also includes: The flue gas composition data and differential pressure gradient data collected in step 1 are simultaneously input into steps 2 and 4; The high-risk area coordinates output in step 2 are synchronously input into the zoned flow control in step 3 and the soot blowing positioning operation in step 5. The axial heater output temperature control data from step 3 is returned to step 2 for dew point prediction.

[0015] Beneficial effects of this invention; The beneficial effects of this invention are reflected in solving the air preheater blockage problem through a multi-level collaborative control mechanism: at the data acquisition layer, high-resolution temperature monitoring and flue gas composition analysis are combined to build a risk identification basis, and spatial coordinate mapping technology enables precise location of the blockage area; at the execution control layer, zoned flow allocation and gradient air temperature regulation form targeted treatment of high-risk areas, and directional enhanced heat exchange of heat transfer medium water improves the wall temperature safety margin; at the collaborative protection layer, differential pressure exceeding the limit triggers a triple response of increased heat transfer medium flow, ammonia injection constraint and acoustic scavenging, and physical scavenging and chemical inhibition work together to block the deposition accumulation chain; at the energy efficiency optimization layer, dynamic adjustment of flue gas temperature and integration of waste heat recovery system realize the cascade utilization of thermal energy, and the model rolling update mechanism continuously optimizes control accuracy; between each level, high-risk coordinate sharing enables precise matching of spatial positioning and execution actions, waste heat production feedback drives adaptive adjustment of flue gas temperature, and air temperature regulation data feedback supports continuous iteration of the prediction model, breaking through the limitations of the existing single-parameter control mode and effectively solving the problems of air preheater blockage and boiler output limitation caused by ammonium bisulfate adhesion. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0017] Figure 1 The flowchart illustrates a method for controlling ammonium bisulfate blockage in an air preheater of a boiler using high-sulfur coal, as provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The technical solutions provided by various embodiments of this invention will be described in detail below with reference to the accompanying drawings. To better understand the objectives of this invention, it will be described in further detail below.

[0019] Please see Figure 1 The present invention provides a method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal, comprising: Step 1: A laser in-situ flue gas analyzer deployed at the tail flue of the boiler collects flue gas composition data; a distributed fiber optic temperature sensor installed at the cold end of the air preheater collects wall temperature distribution data; and a triple redundant differential pressure transmitter on the flue gas side of the air preheater collects differential pressure gradient data. Step 2: The control platform acquires the flue gas composition data from Step 1 and the real-time sulfur parameters of the online coal quality analysis system, and calculates the transient dew point temperature field of ammonium bisulfate; it performs spatial superposition analysis on the wall temperature distribution data from Step 1 and the calculated transient dew point temperature field, and outputs the coordinates of high-risk areas and the temperature deviation. Step 3: The closed-loop heat recovery system receives the coordinates and temperature deviation of the high-risk area from Step 2 and controls the branch flow regulating valve of the heat medium water to perform zoned flow distribution; the axial air heater uses zoned flow to heat and deliver air, so that the cold end wall temperature of the high-risk area is higher than the dew point temperature set value of the area output in Step 2. Step 4: When the differential pressure gradient data in Step 1 exceeds the set threshold, increase the flow rate of the heat transfer medium in the high-risk area to the preset upper limit value, and send an instruction to limit the amount of ammonia injected for denitrification to 1.04-1.07 times the theoretical requirement. Locate the coordinates of the high-risk area in Step 2 and perform sonic purging.

[0020] The ammonium bisulfate blockage control method for air preheaters in boilers using high-sulfur coal, provided by this invention, is implemented through the following progressive technical solution: In the initial stage, a laser in-situ flue gas analyzer deployed at a specific location in the boiler tail flue collects data on the concentrations of sulfur oxides and nitrogen oxides in the flue gas. Simultaneously, distributed fiber optic temperature sensors installed on the surface of the heat transfer elements at the cold end of the air preheater collect axial and radial wall temperature distribution data. A triple-redundant differential pressure transmitter on the flue gas side of the air preheater continuously monitors the differential pressure gradient data. These raw monitoring data provide the basic input for subsequent analysis. After receiving the flue gas composition data, the control platform obtains the sulfur parameters of the current coal sample through real-time interaction with the online coal quality analysis system. Based on this, it calculates the transient dew point temperature field distribution of ammonium bisulfate. Furthermore, it performs spatial coordinate mapping and comparative analysis between the real-time wall temperature distribution data and the dew point temperature field, outputting spatial coordinate information of high-risk areas with temperature deviation indicators.

[0021] After receiving the coordinates and temperature deviation data of the high-risk area, the closed-loop heat recovery system drives the flow regulating valves in the branch pipelines of the heat transfer water system to perform differentiated flow distribution. The axial air heaters exchange heat between the hot and cold fluids according to the distributed heat transfer water flow, and implement zoned gradient heating during the air supply process to ensure that the cold end wall temperature of the high-risk area is stably higher than the dew point temperature setpoint corresponding to that location. When the real-time monitored differential pressure gradient data exceeds the safe operating threshold, the system immediately increases the heat transfer water flow of the corresponding branch in the high-risk area to the preset upper limit value, and at the same time sends a command to the denitrification control system to constrain the actual ammonia injection amount within the theoretical requirement range. Based on the coordinates of the high-risk area, it accurately locates the acoustic energy focusing point and performs directional purging and cleaning operations.

[0022] The distribution of the heat transfer medium flow rate employs an adaptive control algorithm to generate dynamic adjustment commands, altering the flow ratio of each branch through changes in valve opening. This algorithm integrates temperature deviation and location parameters in high-risk areas for multi-dimensional optimization calculations. When identifying areas exceeding temperature limits, it prioritizes increasing the heat exchange intensity in those areas while simultaneously reducing the heat energy allocation weight in non-critical areas. Each independent heat exchange zone of the axial air heater implements corresponding intensity of air transfer medium heating operation based on the received flow parameters. The target wall temperature control value is dynamically corrected with reference to transient dew point temperature prediction data, and the temperature change rate during the heating process is continuously monitored to prevent exceeding safety limits.

[0023] The flue gas temperature regulation is based on wall temperature safety status data and is controlled by the opening degree of the low-temperature economizer bypass valve. The system calculates the required heat load of the heating system and the actual waste heat output in real time. When the waste heat output is detected to be higher than the actual demand, the excess heat is introduced into the heat recovery system through a flow path switching device. In the model optimization stage, wall temperature safety monitoring data and turbine extraction parameters are fed back to the ammonium bisulfate generation prediction model, triggering a rolling update mechanism for prediction parameters. All monitoring data are shared across steps through a parallel transmission architecture. Flue gas composition and differential pressure gradient data are synchronously transmitted to the analysis unit and interlocking control unit. High-risk area coordinate data synchronously drives flow distribution and soot blowing positioning operations. The output data of the heater is returned to support the continuous improvement of the accuracy of the dew point prediction model.

[0024] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: In step 1, the distributed fiber optic temperature sensor collects axial and radial temperature data in a 40-point temperature measurement array divided into 10° sectors. In step 2, the ammonium bisulfate formation rate model is updated based on real-time sulfur parameters. Deviation analysis is performed on the temperature distribution data and transient dew point temperature field in step 1, and areas with deviations > 3℃ are marked as over-limit areas. The control platform outputs the coordinates of the over-limit area to the branch flow regulating valve positioning operation in step 3, which is used to guide the distribution of heat medium water flow in high-risk areas.

[0025] The specific implementation process of the technical solution of this invention includes the following detailed technical features: Distributed fiber optic temperature sensors employ a spatially equidistant arrangement strategy, deploying 40 independent temperature measurement points within each 10° sector area to form a three-dimensional array, accurately acquiring axial and radial temperature distribution data at the cold end of the air preheater; this high-resolution temperature field mapping provides fundamental data support for risk area identification. The control platform receives coal sulfur analysis data in real time, dynamically updates the ammonium bisulfate formation reaction kinetic parameters, and marks areas where the temperature negative deviation continuously exceeds a set threshold as over-limit areas by comparing the transient temperature values ​​of the test points with the theoretical distribution of the dew point temperature field; this judgment logic realizes the order of magnitude conversion from temperature anomaly to risk level. The system transmits the three-dimensional coordinate parameters of the over-limit areas to the heat medium water circulation control unit, driving the branch pipeline flow regulation mechanism to perform spatial positioning operations, implementing differentiated flow allocation strategies for areas with different risk levels.

[0026] In the heat transfer fluid control process, the branch valve position control signal originates from the output of the risk analysis model. When a specific coordinate is identified as an over-limit zone, the valve opening of the corresponding branch in that zone is automatically adjusted to the preset operating range, significantly increasing the heat transfer fluid flow rate to enhance the heat exchange effect, while simultaneously reducing the heat supply intensity in non-critical areas. Each independent heat exchange zone of the axial air heater adjusts the supply air temperature in real time based on changes in the heat transfer fluid flow rate, ensuring that the wall temperature remains consistently above the current zone's dew point critical point. This process continuously monitors the temperature gradient to prevent sudden thermal stress changes from causing equipment damage.

[0027] The risk response mechanism operates in tandem with the thermal system: when differential pressure monitoring data exceeds the safety threshold, a three-level interlock control is triggered. First, the flow rate of the heat transfer medium in the high-risk area is increased to the system design limit. Second, a denitrification ammonia injection constraint command is sent to suppress the formation of new deposits. Finally, the acoustic soot blowing device is driven to accurately locate the coordinates of the over-limit area and implement energy focusing and removal. Simultaneously, the flue gas temperature setpoint is adjusted based on the real-time wall temperature safety margin, and the system thermal balance is maintained by controlling the opening of the low-temperature economizer bypass valve. The heat energy distribution unit compares the heating load with the actual waste heat output and directs the excess heat to the thermal cycle system. The ammonium bisulfate formation prediction model periodically receives feedback on wall temperature status and extraction steam parameters, and uses a rolling optimization algorithm to update the core calculation parameters, forming a self-correcting closed loop of the control strategy. All monitoring data is shared and analyzed across levels through parallel transmission channels. The coordinates of the high-risk area synchronously drive the heat transfer medium distribution and physical removal operations, and the feedback of the heater operation data supports the continuous optimization of the model accuracy.

[0028] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: In step 3, the closed-loop heat recovery system receives the coordinates of the over-limit area and the temperature deviation from step 2, and generates a flow distribution command using a fuzzy proportional integral differential algorithm; the command drives the electric regulating valve group to adjust the flow rate of the heat medium water, so that the primary air heater and the secondary air heater are distributed according to a preset ratio. When a marked over-limit area is identified, the flow rate of the heat medium water in the branch corresponding to the marked over-limit area is increased, while the allocation weight of non-key areas is reduced.

[0029] In the heat transfer fluid flow control stage, the closed-loop heat recovery system receives the spatial coordinates of the over-limit zone and the corresponding temperature deviation data output from step 2. It then processes the input parameters using a fuzzy proportional-integral-differential fusion control algorithm to generate a dynamic flow allocation command signal. This algorithm integrates the over-limit zone location information and temperature deviation for multi-dimensional weight calculation, quantifies the adjustment intensity through a membership function, and outputs a flow control command value that matches the risk level.

[0030] The flow distribution command drives the actuator of the electric regulating valve group to precisely adjust the valve opening according to the command value, so that the primary air heater and secondary air heater loops are configured with heat transfer medium water flow according to a preset basic distribution ratio. This ratio is preset based on the boiler's thermal balance characteristics to meet the air temperature control requirements under normal operating conditions.

[0031] When the system identifies the coordinates of the over-limit zone marked in step 2, the flow regulating valve of the corresponding air heater branch at that coordinate axis position automatically increases its opening, significantly increasing the flow rate of the heat transfer medium in that branch to the preset upper limit range. Simultaneously, a non-critical area flow weight reduction mechanism is implemented, achieving overall system flow balance control by proportionally reducing the valve openings in other areas. This differentiated allocation strategy enables spatially targeted centralized supply of thermal energy resources.

[0032] After receiving the zone flow parameters, each independent heat exchange unit of the axial air heater performs gradient air heating. During the air temperature rise process, the difference between the wall temperature and the transient dew point prediction provided in step 2 is continuously monitored, and the target air temperature is finely adjusted in real time based on the dynamic temperature difference parameter. The heating rate is controlled by the temperature rise rate constraint logic to avoid excessive temperature gradient causing stress damage to the heat transfer elements.

[0033] The flow distribution operation and risk response work in tandem: when differential pressure monitoring exceeds limits, the flow rate of the branch in the over-limit area is automatically increased to the design limit, and the heat medium supply intensity in non-key areas is reduced simultaneously; the acoustic purging device performs directional energy focusing purging based on the coordinates of the over-limit area; the flue gas temperature control dynamically corrects parameters with reference to the wall temperature safety margin; and the waste heat recovery system automatically switches the heat energy flow path according to the heating air load demand. The ammonium bisulfate generation model periodically receives operational data feedback for parameter self-optimization, forming a complete operational closed loop of monitoring, analysis, and execution control.

[0034] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: The axial heater receives the hot water flow rate allocated in step 3 according to the zone and performs gradient heating and air supply operation. Based on the difference between the transient dew point temperature output in step 2 and the measured wall temperature, dynamically adjust the target values ​​for air temperature control in each zone. The rate of temperature change during the heating process is limited to a set safety threshold.

[0035] In the operation of the axial air heater, each independent zone receives the heat transfer fluid flow rate parameters allocated in step 3 and executes zoned gradient heating and air supply operation. This process dynamically adjusts the heat exchange intensity based on the heat transfer fluid flow rate value corresponding to the spatial location of each zone, achieving differentiated increases in air supply temperature. The air heater output continuously monitors the actual wall temperature of each zone and compares it in real time with the transient dew point temperature prediction value provided in step 2, correcting the air temperature control target value based on the dynamic temperature difference data. This correction process employs a closed-loop feedback mechanism to ensure that the wall temperature is always maintained above a safe margin of the dew point temperature.

[0036] The heating process employs a temperature rise rate constraint mechanism, which calculates the temperature change per unit time in real time and limits the rate of temperature rise to a preset safety limit. This constraint logic prevents thermal stress damage to heat transfer elements due to sudden temperature changes, while ensuring the stability of the temperature regulation process. When a specific zone is identified as an over-limit area, the temperature rise rate limit for that zone is automatically adjusted upwards to accelerate wall temperature recovery while maintaining safety.

[0037] The air temperature control system and the heat medium distribution system operate in tandem: changes in the heat medium water flow rate driven by flow distribution commands directly affect the heat exchange intensity of the air heater, while wall temperature monitoring data is fed back to the flow control unit in real time, forming a dynamic adjustment closed loop. When differential pressure exceeds the limit and triggers an interlock response, the high-risk zone simultaneously executes flow rate increase and temperature rise rate adjustment, and the acoustic cleaning device performs directional sediment removal based on the coordinates of the over-limit zone. The flue gas temperature is dynamically set based on the wall temperature safety status, and the waste heat recovery system achieves optimized energy allocation through heat supply and demand balance analysis. The ammonium bisulfate generation model periodically receives wall temperature data and operating parameters, continuously updates the core variables of the prediction algorithm, and continuously optimizes control accuracy.

[0038] Specifically, the present invention relates to a method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal. Step 4 also includes: Increase the flow rate of the heat transfer medium in the secondary air heater to the maximum design value; Send an ammonia reduction command to the denitrification system to limit the ammonia injection rate to 1.04 to 1.07 times the theoretical requirement; Based on the coordinates of the high-risk area in step 2, drive the acoustic soot blower to perform a targeted cleaning operation.

[0039] In the differential pressure gradient over-limit response stage, the system automatically executes multi-level coordinated control operations: First, the flow rate of the heat transfer medium in the secondary air heater circuit is increased to the upper limit of the system design flow rate. This operation is achieved by directly controlling the maximum opening of the heat transfer medium regulating valve; this significantly enhances the heat exchange capacity of high-risk areas and accelerates the recovery of wall temperature. Simultaneously, an ammonia injection constraint command is sent to the denitrification control system. Based on the denitrification efficiency model, the theoretical ammonia demand is calculated, and the actual ammonia injection amount is limited to a reasonable fluctuation range of the theoretical demand value; this constraint mechanism effectively inhibits the new deposition of ammonium bisulfate caused by excessive ammonia escape.

[0040] Based on the high-risk area coordinate parameters output in step 2, the acoustic soot blowing system drives the sound-generating device to precisely locate the target area. The soot blowing operation employs energy focusing technology; the acoustic generator emits mechanical waves of a specific spectrum, creating a localized high-pressure energy field at the target coordinate location. The acoustic oscillations then peel away the deposits adhering to the surface of the heat transfer elements. This process, combined with the increased flow rate of the heat transfer medium, creates a synergistic physical and chemical effect, simultaneously raising the wall temperature to soften the deposits and enhancing the mechanical removal effect.

[0041] Interlocking operation data is managed in a closed loop: after the differential pressure over-limit signal triggers the process, the system monitors the operation execution effect in real time and feeds it back to the control center; the actual temperature recovery rate in high-risk areas serves as the basis for adjusting the thermal medium water regulation, while sediment removal efficiency data supports adaptive optimization of acoustic energy parameters. Information on ammonia consumption changes generated by ammonia injection constraint operations is synchronously transmitted to the ammonium bisulfate formation prediction model, participating in the rolling updates of subsequent dew point temperature field calculation parameters. All operations maintain precise synchronization on the time axis and achieve precise synergy based on the coordinates of the over-limit area in the spatial dimension.

[0042] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: Limiting the amount of ammonia injected during denitrification operations will constrain the actual amount of ammonia injected to between 1.04 and 1.07 times the theoretical requirement. When the acoustic soot blower performs a fixed-point cleaning operation, it generates a modulated pulse sound field based on the high-risk coordinates in step 2.

[0043] In the ammonia injection control stage of denitrification, the system calculates the theoretical ammonia demand based on the denitrification efficiency model and dynamically constrains the actual ammonia injection rate within a reasonable fluctuation range of the theoretical demand value. This constraint is achieved by adjusting the opening of the ammonia injection valve in real time, effectively controlling the ammonia slip rate within a safe threshold and reducing the formation of new ammonium bisulfate deposits from a chemical inhibition perspective. The ammonia injection rate constraint range is dynamically adjusted based on sulfur oxide concentration and flue gas flow parameters, forming a closed-loop control adapted to combustion conditions.

[0044] When the acoustic soot blower performs targeted cleaning, it receives the three-dimensional coordinate parameters of the high-risk area output in step 2 and drives the sound-generating device to generate a modulated pulse sound field with a specific spectrum. This sound field forms local energy focusing at the target coordinate position through phase superposition technology. The sound pressure intensity changes with the envelope of the pulse sequence, generating periodic oscillating shear force, effectively stripping deposits from the surface of the heat transfer element. The acoustic parameters are adaptively adjusted according to the deposit adhesion strength model, and the pulse width and repetition frequency are dynamically optimized with temperature deviation.

[0045] The synergistic effect of soot blowing and heat transfer medium regulation: Increased heat transfer medium water flow softens sediments, reducing their adhesion strength to the sediment wall; modulated pulsed sound field mechanically strips away the softened sediments, significantly improving removal efficiency. Ammonia injection constraint simultaneously reduces the source of new sediment, forming a dual-effect synergistic mechanism of sediment removal and formation inhibition. Operational data is fed back in real time to the ammonium bisulfate formation prediction model, participating in the rolling updates of dew point temperature field calculation parameters and continuously optimizing system control accuracy.

[0046] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: Adjust the opening of the low-temperature economizer bypass valve according to the wall temperature safety status in step 3, so that the flue gas temperature is stabilized in the safe range above the acid dew point. By comparing the required heat load of the heater with the amount of waste heat produced, when there is excess waste heat, the excess heat is introduced into the low-pressure heater system.

[0047] In the flue gas temperature control stage, the system dynamically adjusts the opening of the bypass valve of the low-temperature economizer based on the wall temperature safety status parameters output in step 3. This adjustment operation controls the heat exchange intensity of the flue gas flowing through the low-temperature economizer by changing the flue gas bypass flow ratio, thus maintaining the flue gas temperature stably within the safe operating range above the acid dew point temperature. The target value of the flue gas temperature is dynamically corrected based on the wall temperature safety margin, forming an adaptive control mechanism linked to the blockage risk level.

[0048] The heat recovery system collects real-time data on the heat load demand of the air heaters and the waste heat output parameters of the low-temperature economizer, and performs supply and demand balance analysis using a thermodynamic enthalpy calculation model. When the system detects that the waste heat output continuously exceeds the actual demand of the air heaters, it automatically initiates a heat diversion program. This program controls a three-way switching valve to change the flow direction of the heat transfer medium, directing the excess heat to the low-pressure heater system to participate in the thermodynamic cycle, thus achieving cascaded energy utilization.

[0049] The flue gas temperature regulation and waste heat recovery operation form a coordinated control closed loop: changes in the bypass valve opening directly affect the waste heat output, while the waste heat distribution status is fed back to the flue gas temperature setpoint calculation module; changes in the heat load demand of the heater synchronously trigger adjustments to the waste heat diversion strategy, and the low-pressure heater reduces the amount of steam extracted from the turbine after receiving excess heat. This parameter is fed back to the ammonium bisulfate formation prediction model for parameter optimization. Wall temperature safety monitoring data serves as a prerequisite for flue gas temperature regulation. When the wall temperature safety margin is insufficient, the lower limit of the flue gas temperature setpoint is automatically raised, forming a corrosion-resistant safety barrier.

[0050] The thermal energy management process implements dynamic boundary constraints: the flue gas temperature regulation rate is controlled by a temperature change rate limiter to prevent equipment stress damage caused by sudden changes in flue gas temperature; a hysteresis range is set in the waste heat diversion operation to avoid frequent valve operation; thermal shock protection is implemented when heat is introduced into the low-pressure heater, and the inlet water temperature change gradient is controlled by mixing water regulation. All operational data are transmitted to the central database in real time, supporting visualized analysis of system energy efficiency status and optimization of historical operating modes.

[0051] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: Based on the comparison between the heat load demanded by the heater and the waste heat output, a waste heat dispatching command is output to control the execution of the three-way switching valve; The flue gas temperature adjustment amount is dynamically corrected based on the transient dew point temperature prediction value from step 2.

[0052] In the waste heat dispatching and control stage, the system continuously collects the heat load demand signal of the air heater and the waste heat output data of the low-temperature economizer, and performs real-time comparative analysis using a thermodynamic balance calculation model. When the model output shows that the waste heat output is consistently higher than the actual demand, the system automatically generates a waste heat dispatching command signal. This command signal directly drives the actuator of the three-way switching valve to change the flow path of the heat transfer medium, introducing excess heat into the low-pressure heater system to participate in the thermodynamic cycle. The valve switching process adopts a gradual opening adjustment strategy to avoid hydraulic shock affecting system stability.

[0053] The dynamic correction mechanism for flue gas temperature regulation is implemented based on the transient dew point temperature prediction value provided in step 2. The system compares the prediction value with the current flue gas temperature monitoring value in real time and generates flue gas temperature regulation correction parameters based on the temperature difference calculation results. This correction parameter is input to the control loop of the low-temperature economizer bypass valve, and the flue gas heat exchange efficiency is changed by fine-tuning the opening degree, so that the flue gas temperature accurately matches the dew point temperature safety boundary requirements. The correction process adopts a feedforward-feedback composite control strategy to compensate for the impact of flue gas parameter fluctuations in advance.

[0054] Thermal energy dispatch and flue gas control are coupled in two directions: waste heat diversion operations directly affect the outlet flue gas temperature of the low-temperature economizer, while changes in flue gas temperature are synchronously fed back to the waste heat output calculation model; changes in the heat load demand of the air heater trigger dynamic adjustments to the flue gas temperature setpoint, and changes in the extraction steam rate generated after the low-pressure heater receives waste heat are returned to the ammonium bisulfate formation prediction model. Wall temperature safety monitoring data serves as a boundary constraint for flue gas temperature correction; when insufficient wall temperature safety margin is detected, the flue gas temperature safety threshold is automatically increased.

[0055] The system implements a multi-layered safety protection mechanism: flow rate change limits are set during the three-way valve switching process to prevent pressure fluctuations in the heat transfer medium system; flue gas temperature regulation adopts temperature change rate constraint logic to avoid sudden changes in flue gas temperature; and inlet water temperature gradual change control is implemented when heat is introduced into the low-pressure heater to eliminate the risk of thermal shock. All operational data are synchronized to the central database in real time, supporting operational energy efficiency assessment and historical pattern optimization analysis.

[0056] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: The wall temperature safety data and turbine extraction parameters obtained during step 4 are fed back into the ammonium bisulfate formation prediction model in step 2. The prediction model updates the calculation parameters by executing a rolling optimization algorithm based on the feedback parameters.

[0057] In the model optimization and feedback phase, the system transmits the wall temperature safety monitoring data and turbine extraction parameters collected in real time during step 4 to the input interface of the ammonium bisulfate formation prediction model in step 2. This feedback mechanism enables the prediction model to continuously acquire actual operating state parameters, establishing a dynamic correlation between theoretical calculations and engineering practice. After receiving the feedback data, the prediction model initiates a rolling optimization calculation process, using a recursive least squares algorithm to update the reaction kinetic parameters and heat transfer boundary conditions, ensuring that the predicted transient dew point temperature field continuously approximates the actual operating conditions.

[0058] The model parameter update process is subject to multiple constraints: wall temperature safety data limits the upper limit of dew point temperature prediction, and changes in extraction steam parameters reflect the system's thermal equilibrium state; these two together constitute the boundary conditions for model correction. The optimization algorithm prioritizes adjusting core parameters sensitive to prediction bias, retaining valid historical data for weighted calculation in each iteration to avoid control instability caused by sudden parameter changes. The updated model parameters are immediately used in the prediction of high-risk areas in the next calculation cycle, forming a closed-loop improvement chain from execution feedback to model optimization.

[0059] Feedback data is deeply coupled with multi-system control strategies: changes in wall temperature safety status trigger adjustments to the heat load of the air heater, and fluctuations in extraction steam parameters are linked to waste heat recovery strategies. These factors, fed back to the model, affect the prediction accuracy of high-risk areas. The optimized prediction model outputs a new dew point temperature field, driving dynamic correction of the flue gas temperature setpoint and altering the trigger threshold for acoustic purging operations. All feedback data is timestamped for version tracking, supporting comparative analysis of historical operating modes and current parameters.

[0060] The system implements a rolling optimization protection mechanism: parameter update magnitude is constrained by a rate-of-change limiter to prevent model oscillation; historical data employs an exponentially weighted decay strategy to enhance the influence of recent data; the model validation module performs virtual operating condition tests on the updated parameters, and only after successful validation is the system put into actual control. Optimization process data is synchronously stored in a central database, providing an analytical basis for operational performance evaluation.

[0061] Specifically, the method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in this invention further includes: The flue gas composition data and differential pressure gradient data collected in step 1 are simultaneously input into steps 2 and 4; The high-risk area coordinates output in step 2 are synchronously input into the zoned flow control in step 3 and the soot blowing positioning operation in step 5. The axial heater output temperature control data from step 3 is returned to step 2 for dew point prediction.

[0062] The data transmission mechanism of this invention achieves coordinated control through the following architecture: the raw flue gas composition data collected in step 1 and the differential pressure gradient monitoring values ​​are synchronously input to the risk analysis unit in step 2 and the interlocking control unit in step 4 via parallel transmission channels. This design eliminates the data delay problem caused by existing serial transmission, enabling risk analysis operations and emergency response operations to share a real-time data input source.

[0063] The spatial coordinate parameters of the high-risk area output in step 2 are synchronously transmitted to the zoned flow control unit in step 3 and the soot blowing positioning unit in step 5 via a distributed bus. This transmission mechanism enables the sharing of risk positioning information among multiple execution systems. The zoned flow control unit performs directional distribution of heat transfer fluid based on the coordinate parameters, and the soot blowing positioning unit drives the acoustic energy focusing operation based on the same coordinate parameters. Spatial coordinate sharing breaks through the existing independent operation mode of subsystems, ensuring operational positioning consistency at the physical level.

[0064] After completing the gradient heating operation, the axial air heater in step 3 outputs key state parameters of the air temperature control process in real time. This air temperature control data is returned to the input interface of the ammonium bisulfate generation prediction model in step 2 via a feedback channel. The feedback data includes the actual supply air temperature of each zone of the air heater, the wall temperature change curve, and the temperature rise rate index, providing actual operating condition verification data for the dew point temperature field prediction model.

[0065] The data feedback process forms a triple optimization closed loop: comparing the wind temperature data with the initial prediction value in step 2 generates the first-level error correction; the error analysis results drive the update of the dew point temperature prediction parameters, generating the second-level model optimization; the updated prediction model re-outputs the coordinates of high-risk areas, generating the third-level control accuracy improvement. This closed-loop system continuously iterates, gradually bringing the prediction model output results closer to the actual operating state.

[0066] Wind temperature feedback data is deeply embedded in multi-system collaborative logic: optimized dew point prediction output changes the criteria for identifying high-risk areas, triggering dynamic adjustments to flow allocation strategies; temperature rise rate data affects interlock response threshold settings; actual wall temperature and predicted deviation values ​​participate in the calculation of flue gas temperature correction. All transmission operations use timestamp synchronization technology to ensure timeline alignment of cross-system data.

[0067] The system implements a data integrity guarantee mechanism: redundant check codes are configured for parallel transmission channels; a 2-out-of-3 voting logic is implemented for critical coordinate transmission; and historical averages are automatically used as replacements when abnormal data is reported. The data management system records transmission process status logs to provide analytical basis for fault diagnosis.

[0068] This invention addresses the ammonium bisulfate blockage problem through a three-tiered technical architecture: In the data acquisition layer, a laser in-situ flue gas analyzer, a distributed fiber optic temperature sensor array, and a differential pressure monitoring device are deployed to acquire real-time data on flue gas composition, wall temperature field, and differential pressure gradient. This layer provides multi-dimensional raw input for risk analysis, with the temperature sensors employing a spatially equidistant arrangement strategy to achieve high-resolution axial and radial temperature mapping. In the analysis and execution layer, the control platform integrates coal sulfur parameters to calculate the transient dew point temperature field. Through spatial overlay analysis, it locates areas with excessive temperature deviations and outputs high-risk coordinates to guide zoned flow allocation. The closed-loop heat recovery system drives the heat transfer medium regulating valve based on the coordinate data, ensuring enhanced heat exchange flow in high-risk areas; the axial air heater performs gradient heating and air delivery, dynamically maintaining the wall temperature above the dew point safety boundary.

[0069] In the risk control layer, differential pressure exceeding limits triggers a multi-system coordinated response: the flow rate of the heating medium is increased to the design limit, accelerating the temperature rise in high-risk areas; the ammonia injection constraint mechanism inhibits the formation of new deposits; and the acoustic removal device performs directional deposition and stripping based on high-risk coordinates. This layer forms a dual-effect synergy of physical removal and chemical inhibition, resolving the fundamental contradiction between deposit formation and accumulation. In the energy efficiency optimization layer, the flue gas temperature is dynamically adjusted based on the wall temperature safety margin, and the waste heat recovery system achieves cascaded energy utilization through heat load balance analysis, introducing excess heat into the low-pressure heater. The predictive model rolling update mechanism continuously optimizes control parameters, improving the prediction accuracy of the dew point temperature field through feedback of wall temperature data and extraction steam parameters.

[0070] Each technical layer achieves deep coupling through a data closed loop: high-risk coordinates synchronously drive heat medium distribution and acoustic scavenging operations, achieving precise matching between spatial positioning and execution actions; changes in waste heat output are fed back to the flue gas temperature control module, forming a dynamic balance between heat supply and demand; and wind temperature control data is returned to the prediction model for parameter iterative optimization. This architecture breaks through the limitations of existing single-point control, simultaneously achieving technical effects in three dimensions: blockage suppression, deposit removal, and energy efficiency improvement.

Claims

1. A method for controlling ammonium bisulfate blockage in the air preheater of a boiler co-firing high-sulfur coal, characterized in that, include: Step 1: A laser in-situ flue gas analyzer deployed at the tail flue of the boiler collects flue gas composition data; a distributed fiber optic temperature sensor installed at the cold end of the air preheater collects wall temperature distribution data; and a triple redundant differential pressure transmitter on the flue gas side of the air preheater collects differential pressure gradient data. Step 2: The control platform acquires the flue gas composition data from Step 1 and the real-time sulfur parameters of the online coal quality analysis system, and calculates the transient dew point temperature field of ammonium bisulfate; it performs spatial superposition analysis on the wall temperature distribution data from Step 1 and the calculated transient dew point temperature field, and outputs the coordinates of high-risk areas and the temperature deviation. Step 3: The closed-loop heat recovery system receives the coordinates and temperature deviation of the high-risk area from Step 2 and controls the branch flow regulating valve of the heat medium water to perform zoned flow distribution; the axial air heater uses zoned flow to heat and deliver air, so that the cold end wall temperature of the high-risk area is higher than the dew point temperature set value of the area output in Step 2. Step 4: When the differential pressure gradient data in Step 1 exceeds the set threshold, increase the flow rate of the heat transfer medium in the high-risk area to the preset upper limit value, and send an instruction to limit the amount of ammonia injected for denitrification to 1.04-1.07 times the theoretical requirement. Locate the coordinates of the high-risk area in Step 2 and perform sonic purging.

2. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 1, characterized in that, Also includes: In step 1, the distributed fiber optic temperature sensor collects axial and radial temperature data in a 40-point temperature measurement array divided into 10° sectors. In step 2, the ammonium bisulfate formation rate model is updated based on real-time sulfur parameters. Deviation analysis is performed on the temperature distribution data and transient dew point temperature field in step 1, and areas with deviations > 3℃ are marked as over-limit areas. The control platform outputs the coordinates of the over-limit area to the branch flow regulating valve positioning operation in step 3, which is used to guide the distribution of heat medium water flow in high-risk areas.

3. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 2, characterized in that, Also includes: In step 3, the closed-loop heat recovery system receives the coordinates of the over-limit area and the temperature deviation from step 2, and generates a flow distribution command using a fuzzy proportional integral differential algorithm; the command drives the electric regulating valve group to adjust the flow rate of the heat medium water, so that the primary air heater and the secondary air heater are distributed according to a preset ratio. When a marked over-limit area is identified, the flow rate of the heat medium water in the branch corresponding to the marked over-limit area is increased, while the allocation weight of non-key areas is reduced.

4. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 3, characterized in that, Also includes: The axial heater receives the hot water flow rate allocated in step 3 according to the zone and performs gradient heating and air supply operation. Based on the difference between the transient dew point temperature output in step 2 and the measured wall temperature, dynamically adjust the target values ​​for air temperature control in each zone. The rate of temperature change during the heating process is limited to a set safety threshold.

5. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 1, characterized in that, Step 4 also includes: Increase the flow rate of the heat transfer medium in the secondary air heater to the maximum design value; Send an ammonia reduction command to the denitrification system to limit the ammonia injection rate to 1.04 to 1.07 times the theoretical requirement; Based on the coordinates of the high-risk area in step 2, drive the acoustic soot blower to perform a targeted cleaning operation.

6. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 5, characterized in that, Also includes: Limiting the amount of ammonia injected during denitrification operations will constrain the actual amount of ammonia injected to between 1.04 and 1.07 times the theoretical requirement. When the acoustic soot blower performs a fixed-point cleaning operation, it generates a modulated pulse sound field based on the high-risk coordinates in step 2.

7. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 6, characterized in that, Also includes: Adjust the opening of the low-temperature economizer bypass valve according to the wall temperature safety status in step 3, so that the flue gas temperature is stabilized in the safe range above the acid dew point. By comparing the required heat load of the heater with the amount of waste heat produced, when there is excess waste heat, the excess heat is introduced into the low-pressure heater system.

8. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 7, characterized in that, Also includes: Based on the comparison between the heat load demanded by the heater and the waste heat output, a waste heat dispatching command is output to control the execution of the three-way switching valve; The flue gas temperature adjustment amount is dynamically corrected based on the transient dew point temperature prediction value from step 2.

9. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 8, characterized in that, Also includes: The wall temperature safety data and turbine extraction parameters obtained during step 4 are fed back into the ammonium bisulfate formation prediction model in step 2. The prediction model updates the calculation parameters by executing a rolling optimization algorithm based on the feedback parameters.

10. The method for controlling ammonium bisulfate blockage in the air preheater of a boiler using high-sulfur coal as described in claim 9, characterized in that, Also includes: The flue gas composition data and differential pressure gradient data collected in step 1 are simultaneously input into steps 2 and 4; The high-risk area coordinates output in step 2 are synchronously input into the zoned flow control in step 3 and the soot blowing positioning operation in step 5. The axial heater output temperature control data from step 3 is returned to step 2 for dew point prediction.

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