Intelligent cleaning control method and system for air preheater

Abstract

The application provides an air preheater intelligent cleaning control method and system, and relates to the technical field of air preheater anti-blocking dust removal. The method comprises the following steps: obtaining a blocking index of each radial area divided by an air preheater circulating air bin; calculating a difference between a maximum value and a minimum value of the blocking index of each radial area according to the blocking index; determining a to-be-cleaned area and a cleaning mode according to the relationship between the difference and a first preset threshold and a second preset threshold, and performing a corresponding blowing operation on the to-be-cleaned area; after the blowing is completed, the blocking index of each radial area is re-detected and the difference is recalculated, and when the difference is less than or equal to the second preset threshold, the blowing is ended, otherwise the cleaning is continuously performed. Through the comparison of the relative values of the radial partition and the blocking index, the application realizes accurate identification and adaptive cleaning of the difference blocking, improves the cleaning efficiency and reduces the energy consumption.

Description

Technical Field

[0001] This application relates to the field of air preheater anti-clogging and ash removal technology, and in particular to an intelligent cleaning control method and system for air preheaters. Background Technology

[0002] Rotary air preheaters are key heat exchange equipment in thermal power boilers, using a slowly rotating rotor to exchange heat between flue gas and air. In actual operation, fly ash and ammonium bisulfate on the flue gas side tend to deposit on the cold-end heat storage elements, causing blockage and corrosion. This leads to increased air preheater pressure differential, increased air leakage, and decreased heat exchange efficiency, and in severe cases, forces the unit to reduce load or even shut down.

[0003] Currently, the mainstream technologies for preventing air preheater clogging and cleaning include: traditional methods of steam soot blowing and pyrolysis cleaning, on-demand soot blowing control based on differential pressure monitoring, zoned sealing and heating cleaning, and hot air recirculation and heating drying. These technologies have alleviated the air preheater clogging problem to varying degrees, but they still have significant shortcomings.

[0004] Existing cleaning solutions typically treat all areas of the air preheater uniformly according to a preset, fixed method. However, the actual blockage state may vary in different locations within the air preheater, and a uniform treatment method may result in less than ideal cleaning effects in some areas. Furthermore, existing cleaning modes mostly employ fixed program control, which needs improvement in adaptability to different degrees of blockage. Summary of the Invention

[0005] This application aims to address the technical problem of identifying differential blockages at different locations in an air preheater and adaptively matching cleaning modes.

[0006] To solve the above-mentioned technical problems, the embodiments of this application are implemented through the following aspects.

[0007] In a first aspect, this application provides an intelligent cleaning control method for an air preheater, comprising: acquiring the blockage index of each radial region divided by the air preheater's circulating air chamber; calculating the difference between the maximum and minimum values ​​of the blockage index of each radial region based on the blockage index; determining the area to be cleaned and the cleaning mode based on the relationship between the difference between the maximum and minimum values ​​and a first preset threshold and a second preset threshold; performing a purging operation corresponding to the cleaning mode on the area to be cleaned; after purging is completed, re-detecting the blockage index of each radial region, recalculating the difference between the maximum and minimum values ​​of the blockage index of each radial region; ending the purging when the recalculated difference between the maximum and minimum values ​​is less than or equal to the second preset threshold; otherwise, performing the above steps.

[0008] Further, determining the area to be cleaned and the cleaning mode based on the relationship between the difference between the maximum and minimum values ​​and the first and second preset thresholds includes: when the difference between the maximum and minimum values ​​is greater than the first preset threshold, selecting at most two radial areas with the largest blockage index as the area to be cleaned; determining the ash blockage level based on the relationship between the difference between the maximum and minimum values ​​and the first preset threshold; and executing the corresponding cleaning mode, which includes a simple purging mode, a standard pulse mode, and an enhanced pulse mode; when the difference between the maximum and minimum values ​​is greater than the second preset threshold and less than or equal to the first preset threshold, executing the simple purging mode on at most two radial areas in a rotating pattern.

[0009] Furthermore, the simple purging mode uses a first air volume for continuous purging; the standard pulse mode uses a second air volume for purging followed by a third air volume, where the second air volume is greater than the third air volume; the enhanced pulse mode uses a fourth air volume for purging followed by a fifth air volume, where the fourth air volume is greater than the fifth air volume, and the fourth air volume is greater than the second air volume.

[0010] The blockage indicators include at least one of the following: air volume, pressure, and temperature.

[0011] Further, determining the ash blockage level based on the relationship between the difference between the maximum and minimum values ​​and a first preset threshold includes: when the difference between the maximum and minimum values ​​is greater than the first preset threshold and less than or equal to N times the first preset threshold, it is determined to be a mild blockage; when the difference between the maximum and minimum values ​​is greater than N times the first preset threshold and less than or equal to M times the first preset threshold, it is determined to be a moderate blockage; when the difference between the maximum and minimum values ​​is greater than M times the first preset threshold, it is determined to be a severe blockage; wherein N and M are positive integers, and M > N > 1.

[0012] Furthermore, the step of selecting at most two radial regions with the largest blockage index as the areas to be cleaned includes: when there are multiple radial regions with the same blockage index and all of them are the largest, at most two radial regions are selected according to a preset priority, wherein the preset priority is the order from the inner circle to the outer circle.

[0013] Furthermore, the rotation mode involves opening the channel valves of up to two regions in each radial region in turn according to a set time and sequence, and performing the simple purging mode on the opened radial regions.

[0014] Furthermore, determining the area to be cleaned and the cleaning mode based on the relationship between the difference between the maximum and minimum values ​​and the first and second preset thresholds further includes: when the difference between the maximum and minimum values ​​is greater than a safety threshold, interrupting the current cleaning mode and performing emergency purging with maximum airflow until the blockage index of each radial area falls back below the safety threshold.

[0015] Secondly, this application provides an intelligent cleaning control system for an air preheater, comprising: an air preheater, a circulating air chamber disposed in the air preheater, and a controller, wherein the circulating air chamber is an independent fan-shaped compartment, divided into at least three radial regions from the inner circle to the outer circle; the circulating air chamber connects the cold end and the hot end through a circulating air duct to form a circulating loop; each radial region is provided with an independent channel valve for controlling the opening and closing of the connection between the corresponding region and the circulating air duct; each radial region is provided with an independent blockage index detector for detecting the blockage index of the corresponding region; the circulating air duct is provided with a circulating fan for driving air to flow in the circulating loop; the circulating fan is connected to a frequency converter for adjusting the speed of the circulating fan to control the circulating air volume; the controller is communicatively connected to the blockage index detector, the channel valve, and the frequency converter, and is used to execute the method of any one of claims 1 to 8.

[0016] Furthermore, the circulating air chamber has a hot end and a cold end, and each of the radial regions extends from the hot end to the cold end; the hot end inlet and cold end outlet of each of the radial regions are respectively provided with the channel valve; the circulating air duct is also provided with an adjusting baffle for adjusting the return flow of the circulating air.

[0017] The technical advantages of this application are as follows: It adopts a radial zoning strategy, breaking through the traditional circular zoning approach, which can more accurately reflect the actual blockage distribution and achieve more precise cleaning. The blockage judgment logic, which uses relative value comparison between regions, has self-calibration characteristics, avoiding misjudgments when fixed thresholds change under varying operating conditions. It also features multi-level cleaning modes, automatically matching the cleaning intensity according to the blockage level, achieving an optimal balance between cleaning efficiency and energy consumption. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating an intelligent cleaning control method for an air preheater, provided as an embodiment of this application.

[0019] Figure 2 A top view of the air preheater provided in an embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] The intelligent air preheater cleaning method and system provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0023] Figure 1 A flowchart illustrating an intelligent cleaning control method for an air preheater provided in this application is shown below. Figure 1 As shown, the method includes the following steps.

[0024] S1: Obtain the blockage index of each radial region divided by the air preheater circulating air chamber.

[0025] The circulating air chamber of the air preheater is an independent sector-shaped compartment, located on the air preheater rotor, and distributed around the rotor's central axis along with the flue gas chamber, primary air chamber, and secondary air chamber. The circulating air chamber is divided radially from the inner ring to the outer ring into at least three radial regions, such as... Figure 2 As shown, the circulating air chamber is divided into three radial regions from the inner ring to the outer ring: inner ring region A, middle ring region B, and outer ring region C. Each radial region extends from the hot end to the cold end of the circulating air chamber, and independent channel valves are provided at the hot end inlet and the cold end outlet.

[0026] Each radial zone is equipped with an independent blockage indicator detector to detect the blockage index of the corresponding zone. The blockage indicator detector can be at least one of a pressure sensor, an airflow sensor, or a temperature sensor. The blockage index is at least one of the airflow value, pressure value, or temperature value of each zone in the circulating air chamber.

[0027] When the blockage indicator detector is a differential pressure sensor, it is set at the inlet and outlet of each radial region to measure the pressure difference before and after the air flows through the heat exchange element in that region.

[0028] When the blockage indicator detector is an airflow sensor, it is set in the channel of each radial zone to measure the circulating airflow through that zone.

[0029] When the blockage indicator detector is a temperature sensor, it is set at the outlet of each radial region to measure the air temperature after flowing through that region.

[0030] Methods for obtaining congestion indicators for each radial region include: collecting data periodically according to a preset cycle, such as collecting congestion indicators for each region once every set time; or collecting data in real time in response to triggering conditions.

[0031] S2: Calculate the difference between the maximum and minimum values ​​of the blockage index for each radial region based on the blockage index.

[0032] After obtaining the blockage index of each radial region, calculate the maximum value Max and the minimum value Min, and then calculate the difference Δ=Max-Min.

[0033] For example, when the blockage indicator is a pressure value, if the pressure detected in area A is 2000 Pa, the pressure in area B is 1200 Pa, and the pressure in area C is 1000 Pa, then Max = 2000 Pa, Min = 1000 Pa, and Δ = 1000 Pa.

[0034] S3: Based on the relationship between the difference between the maximum and minimum values ​​and the first and second preset thresholds, determine the area to be cleaned and the cleaning mode, and perform the purging operation corresponding to the cleaning mode on the area to be cleaned.

[0035] A first preset threshold T1 and a second preset threshold T2 are set, where T1 > T2.

[0036] Case 1: When Δ > T1, select at most two radial regions with the largest blockage index as the areas to be cleaned, determine the ash blockage level according to the relationship between Δ and T1, and execute the corresponding cleaning mode.

[0037] When multiple radial regions have the same and maximum blockage index, select at most two radial regions in order from the inner circle to the outer circle.

[0038] The determination of ash blockage level includes: When T1 < Δ ≤ T1 × N, it is determined to be a mild blockage, and a simple purging mode is executed; When T1×N<Δ≤T1×M, it is determined to be a moderate blockage, and the standard pulse mode is executed; When Δ > T1×M, it is determined to be a severe blockage, and the enhanced pulse mode is executed; Where N and M are positive integers, and M > N > 1. For example, N = 2, M = 4.

[0039] The specific methods for the three cleaning modes are as follows: Simple purging mode: Continuous purging using the first air volume. The first air volume can be 60%-80% of the rated air volume of the circulating fan.

[0040] Standard pulse mode: Purging is performed using a second air volume followed by a third air volume, with the second air volume being greater than the third air volume. The second air volume can be 80%-100% of the rated air volume, and the third air volume can be 40%-60% of the rated air volume.

[0041] Enhanced Pulse Mode: The fourth airflow is used for purging, followed by the fifth airflow. The fourth airflow is greater than the fifth airflow, and also greater than the second airflow. The fourth airflow is 100%-120% of the rated airflow, and the fifth airflow is 30%-50% of the rated airflow.

[0042] The purging duration of each cleaning mode can be set according to the actual working conditions. For example, the simple purging mode lasts for 60-120 seconds, while the standard pulse mode and the enhanced pulse mode each pulse cycle is 15-30 seconds, alternating for 3-5 cycles.

[0043] Case 2: When T2 < Δ ≤ T1, the rotation mode is adopted, and the channel valves of up to two regions in each radial region are opened in turn according to the set time and set order, and the simple purging mode is performed on the opened radial regions.

[0044] Safety protection: When Δ is greater than the safety threshold, the current cleaning mode is interrupted and an emergency purging is performed with the maximum air volume until the blockage index of each radial area falls back below the safety threshold.

[0045] S4: After purging is completed, re-detect the blockage index of each radial region, recalculate the difference between the maximum and minimum values ​​of the blockage index of each radial region, and end purging when the recalculated difference is less than or equal to the second preset threshold; otherwise, execute S2 and S3.

[0046] After completing one round of purging, the blockage index data for each radial region is reacquired, and the difference Δ'=Max'-Min' is calculated.

[0047] If Δ'≤T2, the purging ends and the system returns to normal monitoring status.

[0048] If Δ' > T2, continue with steps S2 and S3 to perform the next round of purging.

[0049] Closed-loop control example: Assume T1=500Pa, T2=200Pa, N=2, M=4.

[0050] Initial state: Pressure in area A is 2000 Pa, pressure in area B is 1200 Pa, pressure in area C is 1000 Pa, Δ=1000 Pa, area A is determined to be the area to be cleaned, T1=500 Pa<Δ=T1×2=1000 Pa, therefore simple purging mode is executed.

[0051] After the first round of purging, a retest was conducted: the pressure in area A was 1300 Pa, the pressure in area B was 1100 Pa, and the pressure in area C was 950 Pa. Δ' = 350 Pa. Area A was determined to be the area to be cleaned. T2 = 200 Pa < Δ' < T1 = 500 Pa, and the cycle mode was entered.

[0052] After the second round of purging, the pressure was retested: Area A pressure 1050 Pa, Area B pressure 980 Pa, Area C pressure 900 Pa, Δ' = 150 Pa < T2, purging ended.

[0053] In the above embodiments, the blockage indicator detector can also employ a vibration sensor or an acoustic emission sensor to detect changes in vibration characteristics or airflow noise caused by blockage of the heat exchange element, serving as an auxiliary basis for judging the degree of blockage. In the above embodiments, the cleaning mode can also include an online water washing mode, i.e., low-pressure water rinsing after the purging operation to remove stubborn ash. The water pressure in the online water washing mode can be 0.2-0.5 MPa, and the rinsing duration is 30-60 seconds. As an alternative, when all blockage indicator detectors in the circulating air chamber fail, the system can switch to a backup control mode based on the overall differential pressure of the air preheater, using the total differential pressure at the air preheater inlet and outlet as the control basis, and performing cyclic purging according to a fixed cycle.

[0054] This application also provides an intelligent cleaning control system for an air preheater, which includes an air preheater, a circulating air chamber disposed in the air preheater, and a controller.

[0055] The circulating air chamber is an independent fan-shaped compartment, divided radially into at least three regions from the inner to the outer ring, such as an inner ring region, a middle ring region, and an outer ring region. The circulating air chamber has opposing hot and cold ends, with each radial region extending from the hot end to the cold end. The circulating air chamber connects the cold and hot ends in a closed loop via a circulating air duct, forming a circulation loop. A circulating fan is installed in the circulating air duct to drive the airflow within the loop. Adjustable baffles are also installed on the circulating air duct to regulate the return airflow. The circulating fan is connected to a frequency converter to adjust its speed and control the circulating air volume.

[0056] Each radial zone is equipped with an independent channel valve to control the connection between the corresponding zone and the circulating air duct. Each radial zone has separate channel valves for its hot end inlet and cold end outlet.

[0057] Each radial region is equipped with an independent blockage indicator detector to detect blockage indicators in the corresponding region. The blockage indicator detector can be at least one of a differential pressure sensor, an airflow sensor, or a temperature sensor.

[0058] The controller is communicatively connected to the blockage indicator detector, the channel valve, and the frequency converter to execute the steps in the above method embodiments.

[0059] The circulating air chamber has opposing hot and cold ends, with each radial zone extending from the hot end to the cold end. Each radial zone has a channel valve at its hot end inlet and cold end outlet, allowing independent control of the circulating air in each radial zone by controlling the opening and closing of these valves. Adjustable baffles are also installed on the circulating air duct to regulate the return flow rate of the circulating air.

[0060] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for intelligent cleaning control of an air preheater, characterized in that, include: Obtain the blockage index of each radial region divided by the air preheater circulating air compartment; Calculate the difference between the maximum and minimum values ​​of the blockage index for each radial region based on the blockage index described above; Based on the relationship between the difference between the maximum and minimum values ​​and the first and second preset thresholds, the area to be cleaned and the cleaning mode are determined, and the purging operation corresponding to the cleaning mode is performed on the area to be cleaned, wherein the first preset threshold is greater than the second preset threshold. After purging is completed, the blockage index of each radial region is re-detected, and the difference between the maximum and minimum values ​​of the blockage index of each radial region is recalculated. When the recalculated difference between the maximum and minimum values ​​is less than or equal to the second preset threshold, the purging ends; otherwise, the above steps are performed.

2. The intelligent cleaning control method for air preheaters according to claim 1, characterized in that, The step of determining the area to be cleaned and the cleaning mode based on the relationship between the difference between the maximum and minimum values ​​and a first preset threshold and a second preset threshold includes: When the difference between the maximum and minimum values ​​is greater than the first preset threshold, at most two radial regions with the largest blockage index are selected as the areas to be cleaned. The blockage level is determined according to the relationship between the difference between the maximum and minimum values ​​and the first preset threshold, and the corresponding cleaning mode is executed. The cleaning modes include simple purging mode, standard pulse mode and enhanced pulse mode. When the difference between the maximum and minimum values ​​is greater than the second preset threshold and less than or equal to the first preset threshold, the simple purging mode is executed on at most two radial regions in a rotating pattern.

3. The intelligent cleaning control method for air preheaters according to claim 2, characterized in that, The simple purging mode uses a first air volume for continuous purging; the standard pulse mode uses a second air volume for purging followed by a third air volume, where the second air volume is greater than the third air volume; the enhanced pulse mode uses a fourth air volume for purging followed by a fifth air volume, where the fourth air volume is greater than the fifth air volume and the fourth air volume is greater than the second air volume.

4. The intelligent cleaning control method for air preheaters according to claim 1, characterized in that, The blockage indicators include at least one of the following: air volume, pressure, and temperature.

5. The intelligent cleaning control method for air preheaters according to claim 2, characterized in that, The step of determining the ash-blocking level based on the relationship between the difference between the maximum and minimum values ​​and a first preset threshold includes: When the difference between the maximum and minimum values ​​is greater than the first preset threshold and less than or equal to N times the first preset threshold, it is determined to be a mild blockage; When the difference between the maximum and minimum values ​​is greater than N times the first preset threshold and less than or equal to M times the first preset threshold, it is determined to be a moderate blockage. When the difference between the maximum and minimum values ​​is greater than M times the first preset threshold, it is determined to be a severe blockage; where N and M are positive integers, and M > N > 1.

6. The intelligent cleaning control method for air preheaters according to claim 2, characterized in that, The selection of at most two radial regions with the largest blockage index as the areas to be cleaned includes: When multiple radial regions have the same blockage index and are all at their maximum, at most two radial regions are selected according to a preset priority, which is the order from the inner circle to the outer circle.

7. The intelligent cleaning control method for air preheaters according to claim 2, characterized in that, The rotation mode involves opening the channel valves of up to two regions in each radial region in turn according to a set time and sequence, and performing the simple purging mode on the opened radial regions.

8. The intelligent cleaning control method for air preheaters according to claim 1, characterized in that, The step of determining the area to be cleaned and the cleaning mode based on the relationship between the difference between the maximum and minimum values ​​and the first and second preset thresholds further includes: When the difference between the maximum and minimum values ​​is greater than the safety threshold, the current cleaning mode is interrupted, and an emergency purging is performed with the maximum airflow until the blockage index of each radial area falls back below the safety threshold.

9. An intelligent cleaning control system for an air preheater, characterized in that, include: Air preheater, circulating air compartment installed in the air preheater, and controller, wherein, The circulating air chamber is an independent fan-shaped compartment, divided into at least three radial regions from the inner circle to the outer circle; the circulating air chamber connects the cold end and the hot end through a circulating air duct to form a circulating loop; Each radial region is equipped with an independent channel valve to control the opening and closing of the connection between the corresponding region and the circulating air duct; each radial region is equipped with an independent blockage index detector to detect the blockage index of the corresponding region; The circulating air duct is equipped with a circulating fan to drive air to flow in the circulating loop; The circulating fan is connected to a frequency converter to adjust the speed of the circulating fan in order to control the circulating air volume. The controller is communicatively connected to the blockage indicator detector, the channel valve, and the frequency converter, respectively, and is used to execute the method according to any one of claims 1 to 8.

10. The intelligent cleaning control system for air preheaters according to claim 9, characterized in that, The circulating air chamber has a hot end and a cold end, and each of the radial regions extends from the hot end to the cold end; Each of the radial regions is provided with a channel valve at its hot end inlet and cold end outlet. The circulating air duct is also equipped with an adjusting baffle to adjust the return flow rate of the circulating air.

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