Online cleaning and anti-blocking automatic control system for economizer

Abstract

The invention discloses a coal economizer online cleaning and anti-blocking automatic control system which is mainly composed of a dirt monitoring module, a cleaning decision module, a cleaning execution module, an anti-blocking monitoring module, an anti-blocking decision module and an anti-blocking execution module which are connected through signal lines or a communication network, and data transmission and instruction interaction are achieved. The whole system can automatically make cleaning and anti-blocking decisions according to monitored conditions and execute corresponding operations. Meanwhile, the data recording and analyzing module can record and analyze the operation data, a basis is provided for optimization of the system, the system can continuously learn and adapt to the operation state change of the economizer, and the overall performance of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of economizers, specifically to an automated control system for online cleaning and anti-clogging of economizers. Background Technology

[0002] As a crucial component of a boiler, the economizer's performance has a critical impact on the overall operating efficiency and safety of the boiler. In actual operation, economizers are prone to ash accumulation and blockage. Ash accumulation reduces the economizer's heat transfer efficiency, affecting the boiler's thermal economy; blockage can lead to abnormal pressure increases in the economizer, and even cause safety accidents.

[0003] Currently, economizer maintenance mainly relies on regular manual inspections and cleaning. This method has many drawbacks, such as the inability to detect early signs of ash accumulation and blockage in a timely manner, and the uncertainty of manual operation may lead to incomplete or over-cleaning, thus affecting the economizer's service life. Moreover, manual inspection and cleaning require a significant amount of manpower and time, making this maintenance method inefficient for large power plants and unable to meet the needs of modern production.

[0004] In terms of technical monitoring, while some existing methods can monitor certain operating parameters of the economizer, they suffer from incomplete and inaccurate monitoring. For example, some monitoring systems can only focus on a single operating parameter, such as pressure or temperature, and cannot comprehensively consider the interrelationships between multiple parameters to accurately determine the economizer's operating status. In addition, some monitoring methods have poor adaptability to varying operating conditions and cannot accurately reflect the actual situation of the economizer under different load conditions. Summary of the Invention

[0005] The purpose of this invention is to provide an automated control system for online cleaning and anti-clogging of economizers to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an automated control system for online cleaning and anti-clogging of economizers, comprising:

[0007] Ash and pollution monitoring module: Based on the principle of heat balance, an ash and pollution model is constructed, with the economizer inlet and outlet parameters as lumped parameters, and the following conditions are met: the temperature change of the fluid along the flow direction is small, the thickness of the ash and pollution on the metal pipe wall is the same, and the thermal resistance of the working fluid side and the metal pipe is ignored.

[0008] The cleaning factor is used as a measure of the degree of contamination of the heated surface. The cleaning factor is defined as the ratio of the actual heat transfer coefficient to the theoretical heat transfer coefficient. When the cleaning factor is 1, the heated surface is in an ideal clean state. If the cleaning factor is less than 1, it indicates that the heated surface is contaminated with ash and dirt. The smaller the value, the more serious the contamination.

[0009] It has a submodule for calculating the actual heat transfer coefficient under stable operating conditions and a submodule for calculating the actual heat transfer coefficient under variable operating conditions;

[0010] The actual heat transfer coefficient calculation submodule under stable operating conditions is based on the energy conservation relationship. Given that the heat absorbed by the working fluid, the heat flow of the metal pipe wall and the heat released by the flue gas are equal, and the thermal resistance of the pipe wall and the working fluid is ignored, the actual heat transfer coefficient of the system is equivalent to the heat transfer coefficient of the flue gas side for calculation.

[0011] The actual heat transfer coefficient calculation submodule under variable operating conditions takes into account the changes in heat storage in the metal tube wall and heat storage in the working fluid to correct the heat release on the flue gas side. This correction covers three parts: changes in metal heat storage, changes in working fluid heat storage, and heat absorption in the working fluid.

[0012] It includes a module for calculating the theoretical heat transfer coefficient. This module considers both radiative and convective heat transfer of flue gas and uses the mechanism method to calculate the equivalent radiative heat transfer coefficient and convective heat transfer coefficient respectively, thus obtaining the theoretical heat transfer coefficient as the sum of the two.

[0013] Cleaning decision module: Based on the cleaning factors detected by the dust and dirt monitoring module, a cleaning command is issued when the cleaning factors are lower than the preset threshold.

[0014] Cleaning execution module: After receiving the cleaning command, it performs the cleaning operation on the economizer. This operation includes controlling the start and stop of the cleaning equipment and setting the cleaning parameters.

[0015] Anti-clogging monitoring module: Real-time monitoring of the economizer's operating parameters, including but not limited to the economizer's pressure, temperature, and flow rate. When the operating parameters exceed the normal range, it is determined that the economizer is at risk of clogging.

[0016] Anti-blocking decision module: Based on the operating parameters monitored by the anti-blocking monitoring module, when it is determined that there is a risk of blockage in the economizer, an anti-blocking command is issued;

[0017] Anti-blocking execution module: After receiving an anti-blocking command, it takes anti-blocking measures, including but not limited to adjusting the economizer operating parameters and starting auxiliary equipment.

[0018] Furthermore, the submodule for calculating the actual heat transfer coefficient under stable operating conditions in the ash pollution monitoring module has the following detailed features:

[0019] The calculation of the heat absorbed by the working fluid requires accurate acquisition of the working fluid's flow rate, inlet, and outlet enthalpy. The working fluid flow rate is measured by a flow sensor, and the inlet and outlet enthalpy values ​​can be obtained based on a specific calculation program for the properties of water and water vapor, such as one written according to a standard. Then, the heat is calculated according to formula Q. gz =D gz (h *-h) Calculate the heat absorbed by the working fluid on the working fluid side, where D gz h is the working fluid flow rate. * h and h are the inlet and outlet enthalpies of the working fluid, respectively;

[0020] After determining the heat absorption on the working fluid side, due to limitations in economizer structure and measurement technology, the heat transfer of the flue gas is inversely calculated using equivalent relationships. Considering that the heat transfer resistance on the flue gas side is more than two orders of magnitude larger than that on the working fluid side and the metal tube wall, the thermal resistance of the tube wall and working fluid is ignored, and the actual heat transfer coefficient of the system is equivalent to the heat transfer coefficient on the flue gas side. Then, according to the formula K... y =Q y The calculation is performed using / (AΔt), where Δt is the average heat exchange temperature difference between the flue gas and the working fluid, defined as Δt=(Δt) max -Δt min ) / In(Δt max / Δt min ), Δt max and Δt min These represent the larger and smaller inlet and outlet temperature differences in the working fluid and flue gas, respectively; this ensures the accuracy of the actual heat transfer coefficient calculation under stable operating conditions and provides a key data foundation for accurately monitoring the degree of ash pollution in the economizer.

[0021] Furthermore, the submodule for calculating the actual heat transfer coefficient under varying operating conditions in the ash pollution monitoring module has the following unique features:

[0022] Considering that variable operating conditions typically refer to a load change rate of 3% / min, and with changes in fuel quantity, the unit often operates under variable pressure, resulting in corresponding changes in flue gas temperature, water temperature, and pressure at various points within the furnace; in this case, this submodule calculates the dynamic heat release e on the flue gas side. r In addition to considering the heat absorbed by the working fluid Q gz In addition, it also includes the change in metal heat storage ΔQ jr and the change in heat storage of the working fluid ΔQ gz ;

[0023] Metal heat storage change ΔQ jr Calculate according to the formula Where m js For the mass of the heat-receiving surface tube wall metal, c js t represents the average specific heat capacity of the metal. jx The temperature of the metal tube wall is τ, and the time is τ; the change in heat storage of the working fluid is ΔQ. gz According to the formula Calculate, where m gz c represents the mass of the working fluid inside the heated surface tube wall. gz Let be the average specific heat capacity of the working fluid, and be t. gz working fluid temperature;

[0024] By using this calculation method that comprehensively considers various heat changes under varying operating conditions, the actual heat transfer coefficient can be calculated more accurately, thereby enabling more precise monitoring of the ash and dirt levels of the economizer under varying operating conditions.

[0025] Furthermore, the theoretical heat transfer coefficient calculation module has the following characteristics:

[0026] When considering flue gas radiative heat transfer, based on the fourth power law, the radiative heat transfer coefficient is converted into an equivalent radiative heat transfer coefficient that can be added to or subtracted from the convection coefficient through a specific transformation method; the specific formula is as follows: Where α js α represents the emissivity of the metal pipe wall. y T represents the opacity of ash-containing flue gas at a given temperature. js T and T represent the pipe wall temperature and flue gas temperature, respectively. This precise calculation method for the radiative heat transfer coefficient takes into account various factors such as the emissivity of the metal pipe wall and the emissivity of the ash-containing flue gas, thus improving the accuracy of the theoretical heat transfer coefficient calculation.

[0027] For the convective heat transfer coefficient α d The calculation is based on the specific structural parameters of the economizer tube bundle arrangement as in-line counter-current with forced convection outside the tubes, and the formula α is selected. d =kC z C s (λ / d)Re 0.64 Pr 1 / 3 Where k is the coefficient of the constant term, which needs to be fitted based on the data; C z C s λ is the correction factor for the structural arrangement; d is the thermal conductivity at the average temperature of the flue gas; Re and Pr are the Reynolds number and Prandtl number of the flowing flue gas, respectively, which need to be determined based on the physical properties of the flue gas. By combining this method of calculating the convective heat transfer coefficient with the specific structure of the economizer, the accuracy of the theoretical heat transfer coefficient calculation is further improved.

[0028] Furthermore, the cleaning execution module has the following characteristics:

[0029] The start-up and stop control of the cleaning equipment is intelligent and precise. After receiving the cleaning instruction from the cleaning decision module, the cleaning execution module first selects the most suitable solution from a variety of pre-set cleaning schemes based on the current degree of ash contamination and operating parameters of the economizer. For example, if the degree of ash contamination is light, a low-intensity, short-time cleaning method can be selected; if the degree of ash contamination is heavy, a high-intensity, long-time cleaning method can be selected.

[0030] The cleaning parameters include the flow rate, pressure, and temperature of the cleaning medium. The flow rate can be dynamically adjusted based on the economizer's pipe diameter, length, and degree of ash contamination. If the pipe diameter is large and the ash contamination is light, the flow rate can be appropriately reduced; if the pipe diameter is small and the ash contamination is heavy, the flow rate can be appropriately increased. Similarly, the pressure of the cleaning medium should be adjusted based on the economizer's structure and the degree of ash contamination. If the economizer's structure is robust and the ash contamination is light, the pressure can be appropriately reduced; if the economizer's structure is fragile and the ash contamination is heavy, the pressure can be appropriately increased. The temperature of the cleaning medium can be adjusted based on the nature of the ash contamination. If the ash contamination is formed from easily fusible substances, the temperature can be appropriately increased; if the ash contamination is formed from insoluble substances, the temperature can be appropriately decreased.

[0031] With this intelligent cleaning equipment control and precise cleaning parameter settings, the economizer can be cleaned more effectively, improving cleaning efficiency and reducing damage to the economizer.

[0032] Furthermore, the anti-blocking decision module has the following decision-making basis and method:

[0033] When the anti-blocking monitoring module detects that the economizer's operating parameters are outside the normal range, the anti-blocking decision module first performs a detailed analysis of the operating parameters. For example, for pressure parameters, if the inlet pressure is normal but the outlet pressure is significantly reduced, it may indicate that the economizer is blocked. In this case, further analysis is needed to determine the type of blockage, such as tube bundle blockage or partial pipe blockage. For temperature parameters, if the temperature at a certain part is significantly higher or lower than that at other parts, or if the temperature change does not conform to the normal heat transfer law, it may indicate that the economizer is blocked or has other faults. Further determination of the cause of the fault is needed.

[0034] Based on different changes in operating parameters and possible causes of blockage, the anti-blockage decision module selects the most appropriate measure from a variety of pre-set anti-blockage measures; if the tube bundle is blocked, it may choose to start the soot blower to perform soot blowing operation; if the pipeline is partially blocked, it may choose to adjust the fluid flow rate or pressure in the pipeline, etc.

[0035] Meanwhile, the anti-blocking decision module also considers the current operating status of the economizer, such as load conditions and ash pollution levels. If the economizer is operating at high load and the ash pollution level is high, it may be necessary to select anti-blocking measures more cautiously to avoid causing greater impact on the operation of the economizer. This decision-making method, which comprehensively considers changes in operating parameters, causes of blockage, and the operating status of the economizer, can select anti-blocking measures more accurately and improve the anti-blocking effect.

[0036] Furthermore, the anti-blocking monitoring module monitors the operating parameters in the following ways:

[0037] For economizer temperature monitoring, temperature sensors are installed at different locations on the economizer, including the inlet, outlet, and middle of the tube bundle. By monitoring temperature changes at different locations, the heat transfer status of the economizer and whether there is any blockage can be determined. If the temperature at a certain part is significantly higher or lower than that at other parts, or if the temperature change does not conform to the normal heat transfer law, it may indicate that there is a blockage or other fault in the economizer.

[0038] For economizer flow monitoring, flow sensors are installed at the economizer inlet and outlet. By comparing the inlet flow and outlet flow, if the outlet flow is significantly less than the inlet flow, it may indicate that the economizer is blocked.

[0039] Furthermore, the anti-blocking monitoring module also monitors the parameters on the economizer flue gas side.

[0040] Flue gas flow sensor and flue gas temperature sensor are installed at the flue gas inlet and outlet of the economizer, respectively. The flue gas flow sensor is used to monitor the flue gas flow rate entering and leaving the economizer. By comparing the two flow rate values, it can be determined whether the flue gas flows smoothly in the economizer. If the outlet flue gas flow rate is significantly less than the inlet flue gas flow rate, there may be a blockage in the economizer tube bundle or a partial blockage in the flue.

[0041] Flue gas temperature sensors are used to monitor the temperature of flue gas at the inlet and outlet of the economizer. Under normal circumstances, the temperature of the flue gas decreases as it passes through the economizer due to heat exchange. If the temperature difference between the inlet and outlet flue gas does not conform to the normal heat transfer law, such as the difference being too small or too large, it may indicate that there are problems such as ash accumulation, blockage, or poor heat transfer in the economizer. By monitoring the flue gas side parameters, the operating status of the economizer can be understood more comprehensively from another perspective, and potential blockage risks can be detected in a timely manner.

[0042] Furthermore, when the anti-blocking execution module takes anti-blocking measures, its specific operation for the risk of blockage caused by ash accumulation in the economizer tube bundle is as follows:

[0043] When it is determined that the blockage risk is caused by dust accumulation in the tube bundle, the soot blower should be started first. The starting frequency and blowing time of the soot blower should be adjusted according to the severity of the dust accumulation. For mild dust accumulation, the blowing frequency and blowing time can be appropriately reduced. For example, the blowing frequency can be set to once every 2-3 hours and the blowing time to 5-10 minutes. For moderate dust accumulation, the blowing frequency can be set to once every 1-2 hours and the blowing time to 10-15 minutes. For severe dust accumulation, the blowing frequency can be set to once every 0.5-1 hour and the blowing time to 15-20 minutes.

[0044] During soot blowing, the economizer's operating parameters, such as pressure, temperature, and flow rate, are monitored in real time. The soot blowing effect is judged by observing the changes in these parameters. If the relevant operating parameters gradually return to normal after soot blowing, it indicates that the soot blowing is effective. If the parameters do not improve significantly, it may be necessary to further adjust the soot blowing strategy, such as increasing the soot blowing pressure, changing the soot blowing angle, or replacing the soot blowing equipment. This method of flexibly adjusting the soot blowing operation according to the degree of ash accumulation can more effectively remove ash accumulation in the tube bundle and improve the economizer's operating efficiency.

[0045] Furthermore, the system also includes a data recording and analysis module, the specific functions of which are as follows:

[0046] Data recording function: This module records various operating data of the economizer in real time, including cleaning factors monitored by the ash and pollution monitoring module, operating parameters such as pressure, temperature, and flow rate monitored by the anti-clogging monitoring module, as well as operation records of the cleaning execution module and the anti-clogging execution module, such as cleaning time, cleaning equipment parameters, implementation time and specific measures of anti-clogging measures, etc. Through comprehensive recording of this data, a rich data foundation is provided for subsequent analysis and optimization.

[0047] Data analysis function: Analyzes recorded data, including statistical analysis and trend analysis; for example, by statistically analyzing the average and standard deviation of cleaning factors over different time periods, the fluctuation pattern of economizer pollution can be understood; through trend analysis, the changing trend of operating parameters over time can be observed, and potential blockage risks or cleaning needs can be predicted in advance; based on the analysis results, the thresholds of the cleaning decision module and the anti-blockage decision module can be optimized and adjusted to improve the system's operating efficiency and accuracy; this data recording and analysis module enables the system to continuously learn and optimize its own operating strategies.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] The ash and dirt monitoring module monitors the ash and dirt levels of the economizer in real time, enabling timely detection of ash accumulation and prompt cleaning measures to prevent a decrease in heat transfer efficiency caused by ash buildup. Simultaneously, the anti-clogging monitoring and execution modules effectively prevent and handle blockage issues, ensuring the normal operation of the economizer and reducing the risk of safety accidents caused by blockages.

[0050] The cleaning decision module and the cleaning execution module intelligently select cleaning schemes and set cleaning parameters according to the degree of ash and dirt, which improves the cleaning effect and reduces damage to the economizer. The anti-clogging execution module flexibly adjusts anti-clogging measures according to the cause and degree of clogging, such as the start frequency and time of the soot blower, which can more effectively remove accumulated ash and improve the operating efficiency of the economizer.

[0051] The ash and pollution monitoring module considers the calculation of actual heat transfer coefficients under both stable and variable operating conditions, as well as the precise calculation of theoretical heat transfer coefficients, enabling more accurate monitoring of ash and pollution levels. The anti-clogging monitoring module comprehensively monitors the economizer's pressure, temperature, flow rate, and flue gas-side parameters, and assesses clogging risk through integrated analysis, providing more comprehensive and accurate monitoring compared to existing technologies.

[0052] The entire system can automatically make cleaning and anti-clogging decisions based on the monitored conditions and execute corresponding operations. Simultaneously, the data recording and analysis module can record and analyze operational data, providing a basis for system optimization. This allows the system to continuously learn and adapt to changes in the economizer's operating status, improving overall system performance. Attached Figure Description

[0053] Figure 1 This is a front view schematic diagram of the structure of the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Please see Figure 1 This invention provides a technical solution: an automated control system for online cleaning and anti-clogging of an economizer. The control system mainly consists of an ash and dirt monitoring module, a cleaning decision module, a cleaning execution module, an anti-clogging monitoring module, an anti-clogging decision module, and an anti-clogging execution module. The modules are connected to each other through signal lines or communication networks to realize data transmission and command interaction.

[0056] Gray pollution monitoring module

[0057] 1. Establishment of the ash pollution model

[0058] Based on the principle of heat balance, under the premise that the temperature change of the fluid along the flow direction is small, the thickness of the ash and dirt on the metal tube wall is the same, and the thermal resistance of the working fluid side and the metal tube is ignored, an ash and dirt model is established using the inlet and outlet parameters of the economizer as lumped parameters.

[0059] 2. Cleaning Factor Calculation

[0060] Actual heat transfer coefficient calculation:

[0061] Under steady-state operating conditions: The submodule for calculating the actual heat transfer coefficient under steady-state operating conditions uses the energy conservation principle, taking advantage of the equality of heat absorbed by the working fluid, heat flow through the metal pipe wall, and heat released by the flue gas, and neglecting the thermal resistance of the pipe wall and working fluid, to calculate the actual heat transfer coefficient of the system as equivalent to the heat transfer coefficient on the flue gas side. Specifically, the heat absorbed by the working fluid is calculated according to formula Q. gz =D gz (h * -h) is calculated, where D gz h is the working fluid flow rate. * Let h and h be the inlet and outlet enthalpies of the working fluid, respectively. Then, by using the equivalent relationship, the heat transfer of the flue gas is deduced, and the actual heat transfer coefficient of the system is equivalent to the flue gas side heat transfer coefficient K. y =Q y / (AΔt), where Δt is the average heat exchange temperature difference between the flue gas and the working fluid, defined as Δt=(Δt max -Δt min ) / In(Δt max / Δt min ), Δt max and Δt min These are the larger and smaller temperature differences between the inlet and outlet of the working fluid and the flue gas, respectively.

[0062] Under varying operating conditions: The submodule for calculating the actual heat transfer coefficient under varying operating conditions corrects for the heat release on the flue gas side by considering the heat storage in the metal tube wall and the changes in the working fluid storage. The change in metal heat storage is based on the formula... Calculate, where m js For the mass of the heat-receiving surface tube wall metal, c js t represents the average specific heat capacity of the metal. js The temperature of the metal tube wall is τ, and the time is τ; the change in heat storage of the working fluid is ΔQ. gz According to the formula Calculate, where m gz c represents the mass of the working fluid inside the heated surface tube wall. gz Let be the average specific heat capacity of the working fluid, and be t. gz Working fluid temperature.

[0063] Theoretical heat transfer coefficient calculation: The theoretical heat transfer coefficient calculation module considers both radiative and convective heat transfer from the flue gas. For radiative heat transfer, according to the formula... Calculate the equivalent radiative heat transfer coefficient, where α js α represents the emissivity of the metal pipe wall. y T represents the opacity of ash-containing flue gas at a given temperature. js T and T represent the pipe wall temperature and flue gas temperature, respectively; for convective heat transfer, according to the formula α d =kC z C s (λ / d)Re 0.64 Pr 1 / 3Calculate the convective heat transfer coefficient, where k is the constant term coefficient, which needs to be fitted based on the data; C z C s λ is the correction factor for the structural layout; λ is the thermal conductivity at the average temperature of the flue gas; d is the outer diameter of the pipe; Re and Pr are the Reynolds number and Prandtl number of the flowing flue gas, respectively, which need to be determined based on the physical properties of the flue gas.

[0064] Cleanliness factor: The cleanliness factor is the ratio of the actual heat transfer coefficient to the theoretical heat transfer coefficient, and is used to measure the degree of contamination of the heated surface.

[0065] Cleaning Decision Module

[0066] When the cleaning factor detected by the ash and pollution monitoring module is lower than a preset threshold, the cleaning decision module issues a cleaning command. The threshold can be determined based on factors such as the specific type of economizer, operating conditions, and empirical data.

[0067] Cleaning Execution Module

[0068] 1. Selection and control of cleaning equipment

[0069] Upon receiving a cleaning command, the cleaning execution module selects the most suitable solution from a variety of pre-set cleaning options based on the current level of ash contamination and operating parameters of the economizer. For example, if the level of ash contamination is relatively light, a low-intensity, short-duration cleaning method can be selected, such as low-pressure water rinsing, with a rinsing time of 10-15 minutes; if the level of ash contamination is relatively heavy, a high-intensity, long-duration cleaning method can be selected, such as high-pressure water jet cleaning, with a rinsing time of 30-60 minutes.

[0070] The start-up and shutdown of the cleaning equipment are automatically controlled by the control system. After a cleaning program is selected, the control system will start the cleaning equipment according to the set program and automatically stop the equipment after the cleaning time is completed.

[0071] 2. Cleaning parameter settings

[0072] Cleaning parameters include the flow rate, pressure, and temperature of the cleaning medium. The flow rate of the cleaning medium can be dynamically adjusted according to the economizer's pipe diameter, length, and degree of ash contamination. If the pipe diameter is large and the degree of ash contamination is light, the flow rate can be appropriately reduced, such as setting it to 5-10 cubic meters per hour; if the pipe diameter is small and the degree of ash contamination is heavy, the flow rate can be appropriately increased, such as setting it to 15-20 cubic meters per hour.

[0073] The pressure of the cleaning medium should also be adjusted according to the structure and degree of ash contamination of the economizer. If the economizer has a relatively robust structure and a light degree of ash contamination, the pressure can be appropriately reduced, such as by setting it to 23 MPa; if the economizer has a relatively fragile structure and a heavy degree of ash contamination, the pressure can be appropriately increased, such as by setting it to 58 MPa.

[0074] The temperature of the cleaning medium can be adjusted according to the nature of the ash. If the ash is formed from easily soluble substances, the temperature can be increased appropriately, such as setting it to 60-80℃; if the ash is formed from substances that are not easily soluble, the temperature can be decreased appropriately, such as setting it to 20-30℃.

[0075] Anti-blocking monitoring module

[0076] 1. Pressure monitoring

[0077] Pressure sensors are installed at the economizer's inlet, outlet, and key locations. The inlet pressure sensor monitors the economizer's inlet water pressure, the outlet pressure sensor monitors the economizer's outlet water pressure, and the pressure sensors at key locations monitor pressure changes at areas within the economizer where blockages may occur. The pressure sensors convert the pressure signals into electrical signals and transmit them to the control system.

[0078] By comparing changes in inlet and outlet pressures, as well as pressure at key locations, it can be determined whether the economizer is at risk of blockage. If the inlet pressure is normal but the outlet pressure is significantly reduced, or if there are abnormal fluctuations in pressure at key locations, it may indicate that the economizer is blocked.

[0079] 2. Temperature monitoring

[0080] Temperature sensors are installed at various locations within the economizer, including at the economizer inlet, outlet, and the middle of the tube bundle. These temperature sensors convert temperature signals into electrical signals, which are then transmitted to the control system.

[0081] By monitoring temperature changes at different locations, the heat transfer status of the economizer and the presence of blockages can be determined. If the temperature at one location is significantly higher or lower than that at other locations, or if the temperature change does not conform to normal heat transfer patterns, it may indicate that the economizer is blocked or has other malfunctions.

[0082] 3. Traffic monitoring

[0083] Flow sensors are installed at the inlet and outlet of the economizer. The flow sensors convert the flow signal into an electrical signal and transmit it to the control system.

[0084] By comparing the inlet and outlet flow rates, if the outlet flow rate is significantly less than the inlet flow rate, it may indicate that the economizer is clogged.

[0085] 4. Flue gas side parameter monitoring

[0086] Flue gas flow sensors and flue gas temperature sensors are installed at the inlet and outlet of the economizer, respectively. The flue gas flow sensors monitor the flow rate of flue gas entering and leaving the economizer. By comparing the two flow rate values, it can be determined whether the flue gas flow within the economizer is smooth. If the outlet flue gas flow rate is significantly less than the inlet flue gas flow rate, there may be blockage in the economizer tube bundle or part of the flue gas duct.

[0087] Flue gas temperature sensors are used to monitor the temperature of flue gas at the inlet and outlet of the economizer. Under normal circumstances, the flue gas temperature decreases as it passes through the economizer due to heat exchange. If the temperature difference between the inlet and outlet flue gas does not conform to normal heat transfer patterns, such as being too small or too large, it may indicate problems such as ash accumulation, blockage, or poor heat transfer in the economizer.

[0088] Blocking Decision Module

[0089] 1. Congestion Risk Analysis

[0090] When the anti-blockage monitoring module detects that the economizer's operating parameters exceed the normal range, the anti-blockage decision module first performs a detailed analysis of these parameters. For example, regarding pressure parameters, if the inlet pressure is normal but the outlet pressure is significantly lower, it may indicate that the economizer is blocked. In this case, further analysis is needed to determine the type of blockage, such as tube bundle blockage or partial pipe blockage. Regarding temperature parameters, if the temperature at a certain location is significantly higher or lower than at other locations, or if the temperature change does not conform to normal heat transfer patterns, it may indicate that the economizer is blocked or has other malfunctions, requiring further investigation to determine the cause of the malfunction.

[0091] 2. Selection of prevention and control measures

[0092] Based on different changes in operating parameters and possible causes of blockage, the anti-blockage decision module selects the most appropriate measure from a variety of pre-set anti-blockage measures. If the blockage is in the tube bundle, it may choose to start the soot blower to perform soot blowing; if the blockage is in a localized part of the pipeline, it may choose to adjust the fluid flow rate or pressure in the pipeline.

[0093] Meanwhile, the anti-blocking decision module also considers the current operating status of the economizer, such as load conditions and ash pollution levels. If the economizer is operating at high load and the ash pollution level is high, more cautious anti-blocking measures may be needed to avoid further impacting the economizer's operation.

[0094] Anti-blocking execution module

[0095] 1. Soot blowing operation

[0096] When it is determined that the blockage risk is due to dust accumulation in the tube bundle, the sootblower should be started first. The start frequency and blowing time of the sootblower should be adjusted according to the severity of the dust accumulation. For mild dust accumulation, the blowing frequency and blowing time can be appropriately reduced. For example, the blowing frequency can be set to once every 23 hours, and the blowing time can be 5-10 minutes. For moderate dust accumulation, the blowing frequency can be set to once every 12 hours, and the blowing time can be 10-15 minutes. For severe dust accumulation, the blowing frequency can be set to once every 0.51 hours, and the blowing time can be 15-20 minutes.

[0097] During soot blowing, the economizer's operating parameters, such as pressure, temperature, and flow rate, are monitored in real time. The soot blowing effect is assessed by observing changes in these parameters. If the relevant operating parameters gradually return to normal after soot blowing, the soot blowing is effective; if the parameters do not improve significantly, further adjustments to the soot blowing strategy may be necessary, such as increasing the soot blowing pressure, changing the soot blowing angle, or replacing the soot blowing equipment.

[0098] 2. Other prevention and control measures

[0099] If the blockage is localized, measures such as adjusting the fluid flow rate or pressure within the pipeline may be chosen. Specifically, if a blockage occurs at a specific point in the pipeline, the fluid flow rate can be altered by adjusting the opening of upstream or downstream valves, or the blockage can be alleviated by increasing or decreasing the pressure within the pipeline. Simultaneously, when taking these measures, it is necessary to monitor the economizer's operating parameters in real time to ensure the effectiveness and safety of the measures.

[0100] Data recording and analysis module

[0101] 1. Data Recording

[0102] This module records various operational data of the economizer in real time, including cleaning factors monitored by the ash and pollution monitoring module, operating parameters such as pressure, temperature, and flow rate monitored by the anti-clogging monitoring module, and operation records of the cleaning and anti-clogging execution modules, such as cleaning time, cleaning equipment parameters, implementation time and specific measures for anti-clogging measures, etc. This data is stored in a database in a specific format for subsequent querying and analysis.

[0103] 2. Data Analysis

[0104] The recorded data is analyzed, including statistical analysis and trend analysis. For example, by statistically analyzing the average and standard deviation of cleaning factors over different time periods, the fluctuation pattern of economizer contamination can be understood; by trend analysis, the changing trends of operating parameters over time can be observed, allowing for the prediction of potential blockage risks or cleaning needs. Based on the analysis results, the thresholds of the cleaning decision module and the anti-blockage decision module can be optimized and adjusted to improve the system's operating efficiency and accuracy.

[0105] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An economizer online cleaning and anti-blocking automatic control system, characterized in that: include: Ash pollution monitoring module: The ash pollution model is constructed based on the heat balance principle, with the economizer inlet and outlet parameters as lumped parameters, and the prerequisites that the temperature of the fluid does not change much along the flow direction, the thickness of the ash pollution on the metal pipe wall is the same, and the thermal resistance of the working fluid side and the metal pipe is ignored; The clean factor is used as a measure of the degree of contamination of the heating surface. The clean factor is defined as the ratio of the actual heat transfer coefficient to the theoretical heat transfer coefficient. When the clean factor is 1, the heating surface is in an ideal clean state. If the clean factor is less than 1, it indicates that the heating surface is contaminated by dust and dirt, and the smaller the value, the more serious the contamination. It has a submodule for calculating the actual heat transfer coefficient under stable working conditions and a submodule for calculating the actual heat transfer coefficient under variable working conditions; The actual heat transfer coefficient calculation submodule under stable working conditions is based on the energy conservation relationship. Considering that the heat absorption on the working fluid side, the heat flow of the metal pipe wall and the heat release on the flue gas side are equal, and the thermal resistance of the pipe wall and the working fluid is ignored, the actual heat transfer coefficient of the system is equivalent to the heat transfer coefficient on the flue gas side to achieve calculation; The actual heat transfer coefficient calculation submodule under variable working conditions takes into account the changes in the heat storage of the metal tube wall and the heat storage of the working fluid to correct the heat release on the flue gas side. This correction covers three parts: the change in metal heat storage, the change in working fluid heat storage, and the heat absorption of the working fluid. Contains a theoretical heat transfer coefficient calculation module, which takes into account the radiation heat transfer and convection heat transfer of flue gas, and uses the mechanism method to calculate the equivalent radiation heat transfer coefficient and convection heat transfer coefficient respectively, and then derives that the theoretical heat transfer coefficient is the sum of the two; Cleaning decision module: Based on the cleaning factor monitored by the dust and dirt monitoring module, when the cleaning factor is lower than the preset threshold, a cleaning instruction is issued; Cleaning execution module: after receiving the cleaning instruction, it performs cleaning operation on the economizer, which includes the control of starting and stopping the cleaning equipment and the setting of cleaning parameters; Anti-blocking monitoring module: real-time monitoring of the economizer's operating parameters, including but not limited to the economizer's pressure, temperature and flow rate. When the operating parameters exceed the normal range, it is determined that the economizer has a risk of blockage; Anti-blocking decision module: Based on the operating parameters monitored by the anti-blocking monitoring module, when it is determined that there is a risk of blockage in the economizer, an anti-blocking instruction is issued; Anti-blocking execution module: after receiving the anti-blocking instruction, take anti-blocking measures, which include but are not limited to the adjustment of economizer operating parameters and the start-up of auxiliary equipment.

2. The economizer online cleaning and anti-blocking automatic control system according to claim 1 is characterized by: The actual heat transfer coefficient calculation submodule under stable working conditions in the ash pollution monitoring module has the following detailed features: The calculation of heat absorption on the working fluid side requires accurate acquisition of the flow rate, inlet and outlet enthalpy values ​​of the working fluid; The working fluid flow is measured by a flow sensor, and the inlet and outlet enthalpy values ​​can be obtained based on a specific water and water vapor property calculation program, which can be written according to the IAPWS-IF97 standard, for example; then according to the formula Q gz =D gz (h * -h) Calculate the heat absorption on the working fluid side, where D gz is the working fluid flow rate, h * and h are the inlet and outlet enthalpies of the working fluid, respectively; After determining the heat absorption on the working fluid side, due to the limitations of the economizer structure and measurement technology, the heat transfer of the flue gas is inferred through the equivalent relationship; considering that the heat transfer resistance on the flue gas side is more than two orders of magnitude larger than the thermal resistance on the working fluid side and the metal tube wall, the thermal resistance of the tube wall and the working fluid is ignored, and the actual heat transfer coefficient of the system is equivalent to the heat transfer coefficient on the flue gas side, and according to the formula K y =Q y / (AΔt), where Δt is the average heat exchange temperature difference between flue gas and working fluid, defined as Δt=(Δt max -Δt min ) / In(Δt max / Δt min ), Δt max and Δt min The larger and smaller inlet and outlet temperature differences of the working fluid and flue gas, respectively; It ensures the accuracy of the calculation of the actual heat transfer coefficient under stable operating conditions and provides a key data basis for accurately monitoring the ash contamination level of the economizer.

3. The economizer online cleaning and anti-blocking automatic control system according to claim 2 is characterized by: The submodule for calculating the actual heat transfer coefficient under variable working conditions in the dust pollution monitoring module has the following unique features: Considering that variable operating conditions usually refer to the case where the load rise and fall rate is 3% / min, along with the change in fuel quantity, the unit is often operated at variable pressure, and the flue gas temperature, water temperature and pressure at various points in the furnace are changing accordingly; at this time, this submodule calculates the dynamic heat release e on the flue gas side r In addition to considering the working fluid heat absorption Q gz In addition, it also includes the metal heat storage change ΔQ jr and working fluid heat storage change ΔQ gz ; Metal heat storage change ΔQ jr Calculated according to the formula Where m js is the metal mass of the heated surface tube wall, c js is the average specific heat capacity of the metal, t jx is the metal tube wall temperature, τ is the time; the working fluid heat storage change ΔQ gz According to the formula Calculate, where m gz is the mass of the working fluid in the tube wall of the heating surface, c gz is the average specific heat capacity of the working fluid, t gz Working fluid temperature; Through this calculation method that comprehensively considers various heat changes under variable operating conditions, the actual heat transfer coefficient can be calculated more accurately, thereby more accurately monitoring the ash contamination degree of the economizer under variable operating conditions.

4. The economizer online cleaning and anti-blocking automatic control system according to claim 3 is characterized by: The theoretical heat transfer coefficient calculation module has the following characteristics: When considering the flue gas radiation heat transfer, based on the fourth power law, the radiation heat transfer coefficient is converted into an equivalent radiation heat transfer coefficient that can be added or subtracted with the convection coefficient through a specific conversion method; the specific formula is: where α js is the blackness of the metal tube wall, α y is the blackness of ash-containing flue gas at a certain temperature, T js , T are the tube wall temperature and flue gas temperature respectively; this accurate calculation method for the radiation heat transfer coefficient takes into account multiple factors such as the blackness of the metal tube wall and the blackness of the ash-containing flue gas, thus improving the accuracy of the calculation of the theoretical heat transfer coefficient; For the convection heat transfer coefficient α d According to the specific structural parameters of the economizer tube bundle arrangement of sequential countercurrent flow and forced convection outside the tube, the formula α is selected. d =kC z C s (λ / d)Re 0.64 Pr 1 / 3 ; k is the constant term coefficient, which needs to be fitted according to the data; C z , C s is the correction coefficient of the structural arrangement; λ is the thermal conductivity at the average temperature of the flue gas; d is the outer diameter of the tube; Re and Pr are the Reynolds number and Prandtl number of the flowing flue gas, respectively, which need to be obtained based on the physical properties of the flue gas; this method of calculating the convective heat transfer coefficient combined with the specific structure of the economizer further improves the accuracy of the theoretical heat transfer coefficient calculation.

5. The economizer online cleaning and anti-blocking automatic control system according to claim 3 is characterized by: The cleaning execution module has the following characteristics: The start and stop control of the cleaning equipment is intelligent and precise. After receiving the cleaning instruction issued by the cleaning decision module, the cleaning execution module first selects the most appropriate solution from a variety of pre-set cleaning solutions based on the current dust pollution level and operating parameters of the economizer. For example, if the dust pollution level is light, a low-intensity, short-time cleaning method can be selected; if the dust pollution level is heavy, a high-intensity, long-time cleaning method can be selected. The settings of cleaning parameters include the flow rate, pressure, temperature, etc. of the cleaning medium; The flow rate of the cleaning medium can be dynamically adjusted according to the pipe diameter, length and ash pollution degree of the economizer; If the pipe diameter is large and the dust pollution is light, the flow rate can be appropriately reduced; If the pipe diameter is small and the dust pollution is heavy, the flow rate can be appropriately increased; the pressure of the cleaning medium can also be adjusted according to the structure of the economizer and the dust pollution level; if the structure of the economizer is relatively solid and the dust pollution level is light, the pressure can be appropriately reduced; if the structure of the economizer is relatively fragile and the dust pollution level is heavy, the pressure can be appropriately increased; the temperature of the cleaning medium can be adjusted according to the nature of the dust pollution; If the dust is formed by easily soluble substances, the temperature can be appropriately increased; if the dust is formed by substances that are not easily soluble, the temperature can be appropriately lowered; Through this intelligent cleaning equipment control and precise cleaning parameter setting, the economizer can be cleaned more effectively, the cleaning efficiency can be improved, and the damage to the economizer can be reduced.

6. The economizer online cleaning and anti-blocking automatic control system according to claim 2 is characterized by: The anti-blocking decision module has the following decision basis and method: When the anti-blocking monitoring module detects that the operating parameters of the economizer are beyond the normal range, the anti-blocking decision module first analyzes the operating parameters in detail; for example, for pressure parameters, if the inlet pressure is normal and the outlet pressure is significantly reduced, it may indicate that the economizer is blocked. At this time, it is necessary to further analyze the type of blockage, such as tube bundle blockage or partial pipe blockage; for temperature parameters, if the temperature of a certain part is significantly higher or lower than other parts, or the temperature change does not conform to the normal heat transfer law, it may indicate that the economizer is blocked or has other faults, and the cause of the fault needs to be further determined; According to the changes in different operating parameters and possible causes of blockage, the anti-blockage decision module selects the most appropriate measure from a variety of pre-set anti-blockage measures; if the tube bundle is blocked, the soot blower may be started to perform soot blowing operations; if the pipeline is partially blocked, the fluid flow or pressure in the pipeline may be adjusted; At the same time, the anti-blocking decision module will also take into account the current operating status of the economizer, such as load conditions and ash pollution level; if the economizer is in a high-load operating state and the ash pollution level is heavy, it may be necessary to select anti-blocking measures more carefully to avoid greater impact on the operation of the economizer; this decision-making method that comprehensively considers changes in operating parameters, blockage causes and economizer operating status can more accurately select anti-blocking measures and improve anti-blocking effects.

7. The economizer online cleaning and anti-blocking automatic control system according to claim 1, characterized in that: The anti-blocking monitoring module monitors the operating parameters in the following manner: For the temperature monitoring of the economizer, temperature sensors are installed at different positions of the economizer, including the inlet, outlet and middle of the tube bundle of the economizer. By monitoring the temperature changes at different positions, the heat transfer of the economizer and whether there is blockage can be judged. If the temperature of a certain part is significantly higher or lower than other parts, or the temperature change does not conform to the normal heat transfer law, it may indicate that the economizer is blocked or has other faults. For flow monitoring of the economizer, flow sensors are set at the inlet and outlet of the economizer; by comparing the inlet flow and outlet flow, if the outlet flow is significantly smaller than the inlet flow, it may indicate that the economizer is blocked.

8. The economizer online cleaning and anti-blocking automatic control system according to claim 7, characterized in that: The anti-blocking monitoring module also monitors the operating parameters of the economizer flue gas side: A flue gas flow sensor and a flue gas temperature sensor are respectively installed at the flue gas inlet and outlet of the economizer; the flue gas flow sensor is used to monitor the flue gas flow entering and flowing out of the economizer. By comparing the flow values ​​of the two, it can be determined whether the flue gas flows smoothly in the economizer; If the outlet flue gas flow rate is significantly smaller than the inlet flue gas flow rate, there may be a blockage in the economizer tube bundle or a partial blockage in the flue; The flue gas temperature sensor is used to monitor the temperature of the flue gas at the inlet and outlet of the economizer; Under normal circumstances, the temperature of the flue gas will decrease due to heat exchange when passing through the economizer. If the temperature difference between the inlet and outlet flue gases does not conform to the normal heat transfer law, for example, the difference is too small or too large, it may indicate that the economizer has problems such as dust accumulation, blockage or poor heat transfer. By monitoring the parameters on the flue gas side, we can understand the operating status of the economizer more comprehensively from another perspective and discover potential blockage risks in a timely manner.

9. The economizer online cleaning and anti-blocking automatic control system according to claim 7, characterized in that: When the anti-blocking execution module takes anti-blocking measures, the specific operations for the blockage risk caused by dust accumulation in the economizer tube bundle are as follows: When it is determined that the blockage risk is caused by dust accumulation in the tube bundle, the soot blower is started first to perform the soot blowing operation; the soot blower start-up frequency and soot blowing time are adjusted according to the severity of the dust accumulation; for mild dust accumulation, the soot blowing frequency and soot blowing time can be appropriately reduced, for example, the soot blowing frequency can be set to once every 2-3 hours, and the soot blowing time is 5-10 minutes; for moderate dust accumulation, the soot blowing frequency can be set to once every 1-2 hours, and the soot blowing time is 10-15 minutes; for severe dust accumulation, the soot blowing frequency can be set to once every 0.5-1 hour, and the soot blowing time is 15-20 minutes; During the sootblowing process, the operating parameters of the economizer, such as pressure, temperature and flow, are monitored in real time; the sootblowing effect is judged by observing the changes in these parameters; if the relevant operating parameters gradually return to normal after sootblowing, it means that the sootblowing is effective; if the parameters do not improve significantly, it may be necessary to further adjust the sootblowing strategy, such as increasing the sootblowing pressure, changing the sootblowing angle or replacing the sootblowing equipment; this method of flexibly adjusting the sootblowing operation according to the degree of soot accumulation can more effectively remove soot accumulation in the tube bundle and improve the operating efficiency of the economizer.

10. The economizer online cleaning and anti-blocking automatic control system according to claim 9, characterized in that: The system also includes a data recording and analysis module, whose specific functions are as follows: Data recording function: This module records various operating data of the economizer in real time, including the cleaning factor monitored by the ash and pollution monitoring module, the pressure, temperature, and flow operating parameters monitored by the anti-blocking monitoring module, and the operation records of the cleaning execution module and the anti-blocking execution module, such as the cleaning time, cleaning equipment parameters, and the implementation time and specific measures of anti-blocking measures. Through the comprehensive recording of these data, a rich data foundation is provided for subsequent analysis and optimization; Data analysis function: Analyze the recorded data, including statistical analysis and trend analysis; for example, by statistically analyzing the average value and standard deviation of the cleaning factor in different time periods, the fluctuation pattern of the pollution of the economizer can be understood; Through trend analysis, we can observe the changing trends of operating parameters over time and predict possible blockage risks or cleaning needs in advance. Based on the analysis results, we can optimize the thresholds of the cleaning decision module and the anti-blockage decision module to improve the operating efficiency and accuracy of the system. The setting of this data recording and analysis module enables the system to continuously learn and optimize its own operating strategies.

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