Boiler secondary air distribution control methods, devices, systems, and boiler systems

Abstract

This application discloses a method, apparatus, system, and boiler system for controlling secondary air distribution in a boiler. First, the current alkali metal concentration data is acquired. Then, from several pre-configured secondary air distribution schemes corresponding to different alkali metal concentration data, a target secondary air distribution scheme corresponding to the current alkali metal concentration data is determined. Finally, the secondary air dampers of the boiler system are controlled according to the target secondary air distribution scheme. Since this application aims to keep the furnace flame temperature below a preset first temperature threshold when configuring the boiler's secondary air damper distribution scheme, in practical applications, controlling the secondary air dampers to operate according to the target secondary air distribution scheme matching the current alkali metal concentration can, to a certain extent, reduce the furnace flame temperature, reduce the release of alkali metals from high-alkali fuels, and thus reduce slagging and coking phenomena caused by gaseous alkali metals.

Description

Technical Field

[0001] This application relates to the field of control technology, and more specifically, to a method, device, system, and boiler system for controlling the secondary air distribution of a boiler. Background Technology

[0002] The boiler fuels currently used in boilers, such as Zhundong coal, biomass, municipal solid waste, and chemical waste alcohol and oil, usually contain a large amount of alkali metals, such as sodium (Na) and potassium (K), and can be called high-alkali fuels.

[0003] When high-alkali fuels are burned, the alkali metals in them volatilize into a gaseous phase in the combustion flame. The gaseous alkali metals can cause serious slagging and fouling problems on the heating surfaces, affecting the safety and efficiency of the boiler combustion equipment.

[0004] Therefore, how to solve the problem of slagging and coking caused by alkali metals has become an urgent problem for those skilled in the art. Summary of the Invention

[0005] In view of the above problems, this application is made to provide a boiler secondary air distribution control method, device, system and boiler system to achieve the task of controlling boiler air distribution, thereby achieving the task of controlling the combustion process of high-alkali fuel and reducing slagging and coking caused by gaseous alkali metals.

[0006] The specific plan is as follows:

[0007] Firstly, a method for controlling the secondary air distribution in a boiler is provided, applicable to a boiler system burning high-alkaline fuels. The boiler system includes secondary air dampers, and the method for controlling the secondary air distribution includes:

[0008] Acquire the current alkali metal concentration data, which is detected by alkali metal concentration sensors located at preset positions on the water-cooled walls of the boiler system;

[0009] From a number of pre-configured secondary air distribution schemes corresponding to different alkali metal concentration data, a target secondary air distribution scheme corresponding to the current alkali metal concentration data is determined; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold.

[0010] The secondary air damper is controlled according to the target secondary air distribution scheme.

[0011] Secondly, a boiler secondary air distribution control device is provided, applied to a boiler system burning high-alkaline fuel, wherein the boiler system includes a secondary air damper, and the boiler secondary air distribution control device includes:

[0012] An alkali metal concentration data acquisition unit is used to acquire current alkali metal concentration data, which is data detected by alkali metal concentration sensors arranged at preset positions on the water-cooled walls of the boiler system.

[0013] The air distribution scheme determination unit is used to determine a target secondary air distribution scheme corresponding to the current alkali metal concentration data from a number of pre-configured secondary air distribution schemes that correspond to different alkali metal concentration data; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold.

[0014] The damper control unit is used to control the secondary damper according to the target secondary air distribution scheme.

[0015] Thirdly, a boiler secondary air distribution control system is provided, applied to a boiler system burning high-alkaline fuel, wherein the boiler system includes secondary air dampers, and the boiler secondary air distribution control system includes:

[0016] An alkali metal concentration detection system includes an alkali metal concentration sensor arranged at a preset position on the water-cooled wall of the boiler system, used to detect the current alkali metal concentration data;

[0017] A boiler secondary air distribution control device includes a memory and a processor; the memory is used to store programs; the processor is used to execute the programs to implement the various steps of the above-described boiler secondary air distribution control method.

[0018] Fourthly, a boiler system is provided that burns high-alkaline fuel, and the boiler system includes a secondary air damper and the aforementioned boiler secondary air distribution control system.

[0019] By means of the above technical solution, when configuring the secondary air damper air distribution scheme of the boiler, this application aims to make the furnace flame temperature of the boiler system lower than the preset first temperature threshold. Therefore, in practical applications, by controlling the secondary air damper to work according to the target secondary air distribution scheme that matches the current alkali metal concentration, the furnace flame temperature can be reduced to a certain extent, thereby suppressing the release of alkali metals in high-alkali fuel and reducing slagging and coking caused by gaseous alkali metals. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 A flowchart illustrating a boiler secondary air distribution control method provided in an embodiment of this application;

[0022] Figure 2 This example illustrates a configuration flow diagram for a secondary air distribution scheme.

[0023] Figure 3 An example is a schematic diagram of a boiler system;

[0024] Figure 4 It shows Figure 3 The diagram shows the placement of the spectral probes in the boiler system.

[0025] Figure 5 A schematic diagram of another boiler system is shown;

[0026] Figure 6 It shows Figure 5 The diagram shows the placement of the spectral probes in the boiler system.

[0027] Figure 7 Examples of implementations for Figure 3 or Figure 5 The diagram shows the process of secondary air distribution control in the boiler system.

[0028] Figure 8 This is a schematic diagram of the structure of the boiler secondary air distribution control equipment provided in the embodiments of this application. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] The applicant's research revealed that in boiler systems, the release and migration of alkali metals from high-alkali fuels are closely related to flue gas temperature, which is also a key factor influencing slagging and coking. Specifically, alkali metals are released during the combustion of high-alkali fuels; the higher the temperature and the more complete the combustion, the greater the release of alkali metals, the higher the concentration of gaseous alkali metals, and the higher the likelihood of coking and slagging.

[0031] Based on this, the applicant proposes that controlling the flue gas temperature of the boiler system can reduce slagging and coking to a certain extent. Specifically, this application provides a boiler secondary air distribution control method, device, system, and boiler system, which can be applied to achieve automatic control of boiler air distribution, thereby controlling the flue gas temperature during the combustion of high-alkali fuels and reducing slagging and coking caused by gaseous alkali metals.

[0032] Figure 1 This is a schematic flowchart illustrating a boiler secondary air distribution control method according to an embodiment of this application. The boiler secondary air distribution control method can be applied to boiler systems that burn high-alkaline fuels, and the boiler system may include secondary air dampers.

[0033] Combination Figure 1 As shown, the boiler secondary air distribution control method may include the following steps:

[0034] Step S101: Obtain the current alkali metal concentration data.

[0035] The alkali metal concentration data is data detected by an alkali metal concentration sensor, which can be arranged at a preset position on the water-cooled wall of the boiler system in order to determine the alkali metal concentration in the near-wall region of the water-cooled wall.

[0036] Optionally, the alkali metal concentration sensor can be non-contact. In one possible implementation, the alkali metal concentration sensor can use non-contact spontaneous emission spectroscopy to detect the alkali metal concentration. For example, the alkali metal concentration sensor can be a spectral probe for detecting alkali metal concentration, which has a simple structure and good applicability.

[0037] Furthermore, the type of alkali metal corresponding to the alkali metal concentration data can be set according to the composition of the high-alkali fuel being burned. Specifically, since the alkali metals in the high-alkali fuel burned in the boiler system are mainly sodium (Na) and potassium (K), the alkali metal concentration data can include both Na and K concentration data. For example, for Zhundong coal, the Na concentration is 5 to 10 times the K concentration; therefore, the alkali metal concentration data can include only Na concentration data.

[0038] Step S102: From a number of pre-configured secondary air distribution schemes that correspond to different alkali metal concentration data, determine the target secondary air distribution scheme corresponding to the current alkali metal concentration data.

[0039] The plurality of secondary air distribution schemes are configured according to preset control targets, including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold. It should be noted that by adjusting the air distribution scheme of the secondary air dampers, the furnace flame temperature can be changed; by controlling the furnace flame temperature to be lower than the first temperature threshold, the release of alkali metals from the high-alkali fuel can be reduced, the concentration of gaseous alkali metals can be reduced, thereby reducing slagging and coking caused by gaseous alkali metals.

[0040] Optionally, the peak flame temperature can be determined by measuring with a temperature measuring instrument. For example, if the peak flame temperature measured by the temperature measuring instrument is 1700℃, then the first temperature threshold can be set to 1600℃.

[0041] Step S103: Control the secondary air damper according to the target secondary air distribution scheme.

[0042] Specifically, the aforementioned secondary air distribution scheme may include the opening degree of the secondary air damper. At different opening degrees, the secondary air damper can provide different secondary air volumes. It should be noted that the aforementioned secondary air distribution scheme may include different control objects for different boiler systems. For example, for existing wall-mounted opposed-flow combustion boilers, the opening degree of its damper and the angle of the inner / outer secondary air swirl blades can be controlled to adjust the air volume of the swirl burner; for existing tangential combustion boilers, the opening degree of its multi-layer damper can be controlled to adjust the air volume.

[0043] In addition, the secondary air dampers can be controlled by a distributed control system (DCS) to achieve the target air volume and realize the secondary air distribution control task of the boiler system.

[0044] The boiler secondary air distribution control scheme provided in this application aims to make the furnace flame temperature of the boiler system lower than a preset first temperature threshold when configuring the secondary air damper air distribution scheme of the boiler. Therefore, in practical applications, by controlling the secondary air damper to work according to the target secondary air distribution scheme that matches the current alkali metal concentration, the furnace flame temperature can be reduced to a certain extent, the release of alkali metals can be reduced, and the slagging and coking phenomenon caused by gaseous alkali metals can be reduced.

[0045] In some embodiments provided in this application, the control objective may further include: the near-wall temperature of the water-cooled wall of the boiler system and the furnace outlet temperature are lower than a preset second temperature threshold, the second temperature threshold being set according to the ash melting point of the high-alkali fuel, and the second temperature threshold being lower than the first temperature threshold.

[0046] Optionally, the second temperature threshold can be at least 100°C lower than the ash fusion point of the high-alkali fuel. To reduce adverse effects on combustion, the second temperature threshold can be 100°C to 200°C lower than the ash fusion point of the high-alkali fuel. For example, the coal quality and slagging conditions of the boiler system over the past six months can be analyzed, and the ash fusion point of the coal can be determined by combining the sampling analysis results. Assuming the ash fusion point of the high-alkali fuel is 1300°C, the second temperature threshold can be set to 1100°C.

[0047] By using the aforementioned secondary air damper distribution scheme, and by controlling the secondary air damper to operate according to the target secondary air distribution scheme that matches the current alkali metal concentration, it is possible to reduce the flue gas temperature in the near-wall area of ​​the water-cooled wall and the furnace outlet, while reducing the furnace flame temperature. This can suppress the release and migration of alkali metals in high-alkali fuels to a certain extent, thereby reducing slagging and coking caused by gaseous alkali metals.

[0048] The following describes the specific process of configuring a secondary air distribution scheme based on alkali metal concentration in the embodiments of this application.

[0049] Figure 2 This diagram illustrates a configuration flow chart for a secondary air distribution scheme, combined with... Figure 2 As shown in some embodiments provided in this application, the configuration process of several secondary air distribution schemes corresponding to different alkali metal concentration data may include the following steps:

[0050] Step S201: Establish a combustion prediction model for the boiler system.

[0051] The combustion prediction model can provide the flue gas temperature distribution of the boiler system under different operating conditions, thus providing a basis for configuring the secondary air distribution scheme.

[0052] Step S202: Configure a secondary air distribution scheme based on flue gas temperature.

[0053] The flue gas temperature mentioned above can be characterized by the temperature data of preset measuring points in the combustion zone of the boiler system, which can be obtained manually using a high-temperature thermometer.

[0054] Specifically, step S202 above may include steps A to B:

[0055] Step A: For each set of preset operating condition parameters of the boiler system, perform the following steps A1 to A3:

[0056] Step A1: Obtain the temperature data corresponding to the operating condition parameters.

[0057] The temperature data may include the temperature data of the preset measuring points in the combustion zone of the boiler system, which may be obtained by measurement.

[0058] It should be noted that, based on the operating condition parameters and the temperature data, the combustion prediction model can be used to simulate the operating conditions of the boiler system. For example, the combustion prediction model can calculate the flue gas temperature distribution of the boiler system under the current operating conditions. Based on this, when the temperature in the combustion zone of the furnace is detected to be high, the air distribution scheme of the secondary damper can be adjusted to reduce the temperature inside the furnace.

[0059] Step A2: Continuously adjust the secondary air distribution parameters of the boiler system until the flue gas temperature distribution provided by the combustion prediction model is monitored to meet the above control objectives.

[0060] The air distribution parameters of the boiler system may include the opening degree of the secondary air damper. Monitoring that the control objectives are met can refer to: monitoring that the furnace flame temperature is lower than the first temperature threshold, monitoring that the water-cooled wall near-wall temperature is lower than the second temperature threshold, and monitoring that the furnace outlet temperature is lower than the second temperature threshold. Optionally, when adjusting the secondary air distribution parameters of the boiler system, in addition to considering the above control objectives, optimal combustion efficiency and NOx emission principles can also be considered. Specifically, the NOx concentration data at the furnace outlet of the boiler system can be observed using the combustion prediction model, and the optimal operating parameters of the secondary air damper under the current operating conditions can be obtained through comprehensive analysis. It should be noted that by controlling the secondary air damper to operate according to the optimal operating parameters, the furnace flame temperature, water-cooled wall near-wall temperature, and furnace outlet temperature can be lower than their respective temperature thresholds, ensuring that the oxygen concentration in the boiler meets the preset optimal combustion conditions and that the NOx concentration at the furnace outlet meets the optimal NOx emission conditions.

[0061] Step A3: Record the current air distribution parameters of the boiler system as a secondary air distribution scheme corresponding to the temperature data.

[0062] Step B: After obtaining several sets of records, configure several secondary air distribution schemes corresponding to different temperature data.

[0063] Step S203: Configure a secondary air distribution scheme based on alkali metal concentration.

[0064] Specifically, step S203 may include: based on the pre-established mapping relationship between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point, converting the several secondary air distribution schemes corresponding to different temperature data into several secondary air distribution schemes corresponding to different alkali metal concentration data.

[0065] In some embodiments provided in this application, step S201, establishing the combustion prediction model of the boiler system, may include the following steps C to F:

[0066] Step C: Obtain several sets of historical data.

[0067] The historical data may include: the operating condition parameters of the boiler system, the temperature data of the corresponding preset measuring points, and the temperature data of several measuring points at the furnace outlet of the boiler system. The aforementioned operating condition parameters can be obtained by the experimental and distributed control system (DCS) and may include: unit load, coal quality, coal mill combination mode, air volume, air temperature, secondary damper opening, and other operating parameters.

[0068] Step D: Based on the structural parameters of the boiler system, establish a boiler structural model.

[0069] For example, a 3D modeling software (such as Inventor, Solidworks, etc.) can be used to create a boiler structural model at a 1:1 scale based on the structural parameters of the boiler system, such as the dimensions of the boiler air box, air duct, secondary air nozzle, burner, furnace, etc.

[0070] Step E: Based on the boiler structure model, perform fluid dynamics simulation according to different operating condition parameters to establish an initial prediction model.

[0071] For example, the boiler structure model established in step D can be imported into CFD simulation software (Computational Fluid Dynamics, CFD), such as ANSYS, and then the equations for heat transfer, flow, pulverized coal combustion can be opened. Based on parameters such as unit load, coal quality, coal mill combination mode, and secondary damper opening, the initial prediction model of the boiler system can be established using data simulation calculation.

[0072] Step F: Using the temperature data of the preset measuring points corresponding to the operating condition parameters of each group and the temperature data of several measuring points at the furnace outlet, the initial prediction model is corrected to obtain the combustion prediction model of the boiler system.

[0073] The combustion prediction model obtained in step F matches the aforementioned historical data sets better and more closely approximates the actual operating conditions of the boiler system. Therefore, the combustion prediction model can provide a more accurate distribution of the component fields, velocity fields, and temperature fields of the boiler system.

[0074] The combustion prediction model described above provides information such as the flue gas temperature distribution of the boiler system, which can be used to determine the location of the alkali metal concentration sensor.

[0075] In some embodiments provided in this application, the preset location may be: a region on the water-cooled wall that is prone to slagging, determined based on the temperature distribution of the boiler system provided by the combustion prediction model.

[0076] The aforementioned slagging region can refer to the high-temperature region of the water-cooled wall near the wall that is prone to reaching the second temperature threshold, as determined by the temperature distribution of the boiler system provided by the combustion prediction model.

[0077] In one possible implementation, the alkali metal concentration sensor can be a spectral probe, which, together with the monitoring host and professional analysis software, constitutes an online alkali metal monitoring system for detecting and outputting alkali metal concentration data.

[0078] In some embodiments provided in this application, the mapping relationship between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point can be established through the following steps:

[0079] Based on the alkali metal concentration data at the preset location and the temperature data at the preset measuring point under different operating conditions, a correlation analysis is performed on the alkali metal concentration and the flue gas temperature, and a correlation function between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point is fitted to characterize the mapping relationship.

[0080] Optionally, the boiler system can be a tangential combustion boiler, which may have multiple layers of secondary air and multiple layers of SOFA (Separated Burnout Air) secondary air. Each layer of secondary air has an individual damper for control, and combustion can be organized to match the target air volume by adjusting the opening of the multiple dampers. For example, Figure 3 A schematic diagram of a boiler system is shown. This boiler system can be a 300MW tangential combustion boiler burning Zhundong coal. The boiler has six layers of secondary air (AA, AB, BC, CD, DE, EF) and four layers of SOFA secondary air. Based on the above scheme, a combustion prediction model for this boiler can be established. This model can determine the locations of the secondary air in the combustion zones DE and EF of the furnace, as well as the locations of the secondary air in the SOFA and lower parts, where temperatures are prone to exceed limits. Based on this, spectral probes can be deployed in the aforementioned areas prone to slagging. For example, Figure 4 It shows Figure 3 The diagram shows the placement of the spectral probes in the boiler system, combined with... Figure 4 As shown, three spectral probes can be arranged on the front and rear walls and the two side walls of the easily slagging area, for a total of 12 spectral probes, so as to detect the alkali metal concentration and flue gas temperature at that location.

[0081] Optionally, the boiler system can be a wall-mounted opposed-flow combustion boiler, which can be equipped with multiple layers of swirl burners and one layer of burnout air. Combustion can be organized by adjusting the secondary air volume of the swirl burners through adjusting the opening of the damper and the angle of the inner / outer secondary air swirl blades. For example, Figure 5 A schematic diagram of another boiler system is shown. This boiler system can be a 600MW wall-mounted opposed-fired boiler burning 20%–30% Zhundong coal. Based on the above scheme, a combustion prediction model for this boiler can be established. This model can determine the location of the uppermost swirl burner in the furnace combustion zone and the areas above it prone to exceeding limits. Based on this, spectral probes can be placed in the aforementioned areas prone to slagging. For example, Figure 6 It shows Figure 5 The diagram shows the placement of the spectral probes in the boiler system, combined with... Figure 6 As shown, four spectral probes can be arranged on each of the two side walls of the easily slagging area, for a total of eight spectral probes, so as to detect the alkali metal concentration and flue gas temperature at that location.

[0082] Figure 7 Examples of implementations for Figure 3 or Figure 5 The diagram shows the process of secondary air distribution control in the boiler system. (Combined with...) Figure 7 As shown, the process may include:

[0083] First, several sets of historical data are configured. Specifically, the operating parameters of the boiler system are obtained by the distributed control system (DCS) and experiments, such as unit load, coal quality, coal mill combination, air volume, air temperature, and secondary damper opening. Then, the preset measurements of the furnace combustion zone and the temperature data of several measuring points at the furnace outlet are obtained, and several sets of historical data are configured.

[0084] Based on this, according to the structural parameters of the boiler system, such as the dimensions of the wind box, air duct, secondary air nozzle, burner, and furnace of a tangential combustion boiler, and the dimensions of the wind box, air duct, swirl burner, burnout air, and furnace of a wall-mounted opposed combustion boiler, a boiler structural model is established at a 1:1 scale. On this basis, an initial prediction model of the boiler system is established using numerical simulation calculations, and then the model is corrected using temperature data to obtain the combustion prediction model of the boiler system.

[0085] Based on the established combustion prediction model, the location of the spectral probe used to collect temperature and alkali metal concentration is determined, and an online alkali metal monitoring system is installed. This system may include the spectral probe and the monitoring host.

[0086] The operating status of the boiler system over the past six months, including coal quality, slagging, and corrosion, is analyzed. Combined with sampling analysis results, the coal ash fusion point is determined. The peak flame temperature is measured using temperature measuring instruments to determine target control limits based on the coal ash fusion point and peak flame temperature, namely, the first temperature threshold and the second temperature threshold. For example, for a 300MW tangential combustion boiler burning Zhundong coal, the peak flame temperature is determined to be 1700℃ and the coal ash fusion point to be 1300℃. Based on this, the highest flame temperature in the boiler system's furnace should be below 1600℃, and the highest temperature in the near-wall zone of the furnace combustion area and at the furnace outlet should be below 1100℃. In other words, the first temperature threshold is set to 1600℃, and the second temperature threshold is set to 1100℃. For example, for a 600MW wall-mounted opposed-fired boiler that burns 20% to 30% Zhundong coal, the peak flame temperature can be determined to be 1750℃ and the ash fusion point of the coal to be 1350℃. Based on this, it can be determined that the highest flame temperature in the furnace of the boiler system should be lower than 1650℃, and the highest temperature in the near-wall zone of the furnace combustion area and the furnace outlet should be lower than 1150℃. That is, the first temperature threshold is set to 1650℃ and the second temperature threshold is set to 1150℃.

[0087] Then, under different operating conditions, the secondary air distribution scheme of the boiler system is analyzed to determine the relatively optimal secondary air distribution scheme. For example, the opening degree of each layer of dampers in a tangential combustion boiler is analyzed to determine the relatively optimal damper opening degree. Similarly, the opening degree of each layer of dampers and the swirl blade angle in a wall-mounted opposed combustion boiler are analyzed to determine the relatively optimal damper opening degree and swirl blade angle. Based on this, considering the target control limits, optimal combustion efficiency, and optimal NOx emissions, a combustion prediction model is used to calculate and optimize the secondary air distribution scheme, resulting in a secondary air distribution scheme based on flue gas temperature.

[0088] According to Figure 4 or Figure 6 The alkali metal concentration data (e.g., Na concentration data), temperature data, and calculation results of the combustion prediction model detected by the deployed spectral probe are used to obtain the correlation between alkali metal concentration and flue gas temperature. Through data analysis, the correlation function between alkali metal concentration and flue gas temperature is fitted, and a secondary air distribution scheme based on alkali metal concentration is configured to realize the secondary air distribution control scheme provided in the embodiments of this application.

[0089] Based on the boiler secondary air distribution scheme provided in this application embodiment, the matching relationship between alkali metal concentration data and the optimal secondary air distribution scheme (including the opening degree of each layer of dampers and the angle of the swirl blades, or the opening degree of each layer of dampers) can be edited into a control strategy that can be recognized by the distributed control system (DCS). When the DCS detects changes in operating parameters, such as changes in the load, coal quality, and coal mill combination of the boiler system, the DCS adjusts the secondary air dampers according to the corresponding target secondary air distribution scheme to achieve the target air volume. This achieves the task of fine adjustment of air distribution and optimization of combustion conditions in the furnace, reducing slagging and coking caused by alkali metals, realizing intelligent targeted treatment of slagging and coking phenomena in the combustion process of high-alkali fuels, and improving the safety and economy of boiler operation. In addition, the proportion of Zhundong coal used can be increased. For example, for a 600MW wall-mounted opposed-fired boiler, the proportion of Zhundong coal used can be increased by 20% using the scheme of this application.

[0090] Compared to the existing scheme where operators adjust the air distribution based on the furnace temperature measured by a high-temperature thermometer to control the release and conversion of alkali metals, this scheme provides a more intuitive and accurate basis for air distribution adjustment through a combustion prediction model. In addition, this scheme can rely on a distributed control system (DCS) to realize the automatic control of secondary air dampers, eliminating the need for manual trial and error during boiler system operation and reducing the skill and technical requirements for operators.

[0091] The boiler secondary air distribution control device provided in the embodiments of this application is described below. The boiler secondary air distribution control device described below and the boiler secondary air distribution control method described above can be referred to in correspondence.

[0092] The boiler secondary air distribution control device provided in this application embodiment can be applied to boiler systems burning high-alkaline fuels, wherein the boiler system may include secondary air dampers. The boiler secondary air distribution control device may include:

[0093] An alkali metal concentration data acquisition unit is used to acquire current alkali metal concentration data, which is data detected by alkali metal concentration sensors arranged at preset positions on the water-cooled walls of the boiler system.

[0094] The air distribution scheme determination unit is used to determine a target secondary air distribution scheme corresponding to the current alkali metal concentration data from a number of pre-configured secondary air distribution schemes that correspond to different alkali metal concentration data; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold.

[0095] The damper control unit is used to control the secondary damper according to the target secondary air distribution scheme.

[0096] In some embodiments provided in this application, the control objective may further include: the near-wall temperature of the water-cooled wall of the boiler system and the furnace outlet temperature are lower than a preset second temperature threshold, the second temperature threshold being set according to the ash melting point of the high-alkali fuel, and the second temperature threshold being lower than the first temperature threshold.

[0097] In some embodiments provided in this application, the boiler secondary air distribution control device may further include a secondary air distribution scheme configuration unit for configuring several secondary air distribution schemes corresponding to different alkali metal concentration data.

[0098] Based on the above, the process by which the secondary air distribution scheme configuration unit configures the several secondary air distribution schemes corresponding to different alkali metal concentration data may include:

[0099] A combustion prediction model for the boiler system is established, which can provide the flue gas temperature distribution of the boiler system under different operating conditions.

[0100] For each set of preset operating condition parameters of the boiler system: acquire temperature data corresponding to the operating condition parameter, the temperature data including temperature data of preset measuring points in the combustion zone of the boiler system; continuously adjust the secondary air distribution parameters of the boiler system, the secondary air distribution parameters including the damper opening of the secondary air damper, until the flue gas temperature distribution provided by the combustion prediction model detects that the furnace flame temperature is lower than the first temperature threshold, the water-cooled wall near-wall temperature is lower than the second temperature threshold, and the furnace outlet temperature is lower than the second temperature threshold; record the current secondary air distribution parameters of the boiler system as a secondary air distribution scheme corresponding to the temperature data; configure several secondary air distribution schemes corresponding to different temperature data.

[0101] Based on the pre-established mapping relationship between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point, the several secondary air distribution schemes corresponding to different temperature data are converted into several secondary air distribution schemes corresponding to different alkali metal concentration data.

[0102] In some embodiments provided in this application, the process by which the secondary air distribution scheme configuration unit establishes the combustion prediction model of the boiler system may include:

[0103] Acquire several sets of historical data, including: the operating condition parameters of the boiler system, the temperature data of the corresponding preset measuring points, and the temperature data of several measuring points at the furnace outlet of the boiler system.

[0104] Based on the structural parameters of the boiler system, a boiler structural model is established;

[0105] Based on the boiler structure model, fluid dynamics simulations are performed according to different operating condition parameters to establish an initial prediction model; the operating condition parameters include: unit load, coal quality, coal mill combination mode, and secondary damper opening.

[0106] By using the temperature data of the preset measuring points corresponding to each of the operating condition parameters in each group and the temperature data of several measuring points at the furnace outlet, the initial prediction model is corrected to obtain the combustion prediction model of the boiler system.

[0107] In some embodiments provided in this application, the preset location may be: a region on the water-cooled wall that is prone to slagging, determined based on the temperature distribution of the boiler system provided by the combustion prediction model.

[0108] In some embodiments provided in this application, the alkali metal concentration sensor can detect the alkali metal concentration using non-contact spontaneous emission spectroscopy.

[0109] In some embodiments provided in this application, the process of establishing the mapping relationship between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point may include:

[0110] Based on the alkali metal concentration data at the preset location and the temperature data at the preset measuring point under different operating conditions, a correlation analysis is performed on the alkali metal concentration and the flue gas temperature, and a correlation function between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point is fitted to characterize the mapping relationship.

[0111] The boiler secondary air distribution control device provided in this application embodiment can be applied to boiler secondary air distribution control equipment, such as terminals with data processing capabilities: computers, servers, cloud computing, etc. Optionally, the boiler secondary air distribution control device can be applied to boiler systems burning high-alkaline fuels, and the boiler system may include secondary air dampers. Figure 8 The hardware structure block diagram of the boiler secondary air distribution control equipment is shown. (Refer to...) Figure 8 The hardware structure of the boiler secondary air distribution control equipment may include: at least one processor 1, at least one communication interface 2, at least one memory 3, and at least one communication bus 4.

[0112] In this embodiment of the application, the number of processor 1, communication interface 2, memory 3, and communication bus 4 is at least one, and processor 1, communication interface 2, and memory 3 communicate with each other through communication bus 4;

[0113] Processor 1 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0114] Memory 3 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device;

[0115] The memory stores a program, which the processor can call. The program is used for:

[0116] Acquire the current alkali metal concentration data, which is detected by alkali metal concentration sensors located at preset positions on the water-cooled walls of the boiler system;

[0117] From a number of pre-configured secondary air distribution schemes corresponding to different alkali metal concentration data, a target secondary air distribution scheme corresponding to the current alkali metal concentration data is determined; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold.

[0118] The secondary air damper is controlled according to the target secondary air distribution scheme.

[0119] Optionally, the refined and extended functions of the program can be found in the description above.

[0120] Based on the above, this application provides a boiler air distribution control system that can be applied to boiler systems that burn high-alkaline fuels, wherein the boiler system may include secondary dampers.

[0121] The boiler secondary air distribution control system may include: an alkali metal concentration detection system and the aforementioned boiler secondary air distribution control equipment.

[0122] The alkali metal concentration detection system may include an alkali metal concentration sensor arranged at a preset position on the water-cooled wall of the boiler system for detecting the current alkali metal concentration data.

[0123] Optionally, the alkali metal concentration detection system may further include a monitoring host for collecting alkali metal concentration data detected by the alkali metal concentration sensor, so that the boiler secondary air distribution control equipment can acquire it.

[0124] Optionally, the alkali metal concentration detection system can also be used to establish a mapping relationship between flue gas temperature and alkali metal concentration using specialized analysis software.

[0125] Optionally, the location of the alkali metal concentration sensor can be referred to the description in the section on boiler secondary air distribution control method above.

[0126] This application embodiment also provides a boiler system that burns high-alkaline fuel. The boiler system may include: a secondary air damper and the aforementioned boiler secondary air distribution control system.

[0127] Optionally, further descriptions of the boiler system can be found above.

[0128] This application embodiment also provides a storage medium that can store a program suitable for execution by a processor, the program being used for:

[0129] Acquire the current alkali metal concentration data, which is detected by alkali metal concentration sensors located at preset positions on the water-cooled walls of the boiler system;

[0130] From a number of pre-configured secondary air distribution schemes corresponding to different alkali metal concentration data, a target secondary air distribution scheme corresponding to the current alkali metal concentration data is determined; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold.

[0131] Control the secondary air dampers of the boiler system according to the target secondary air distribution scheme.

[0132] Optionally, the refined and extended functions of the program can be found in the description above.

[0133] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0135] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling secondary air distribution in a boiler, characterized in that, A boiler system for burning high-alkaline fuels, the boiler system including secondary air dampers, and the boiler secondary air distribution control method including: Acquire the current alkali metal concentration data, which is detected by alkali metal concentration sensors located at preset positions on the water-cooled walls of the boiler system; From a number of pre-configured secondary air distribution schemes corresponding to different alkali metal concentration data, a target secondary air distribution scheme corresponding to the current alkali metal concentration data is determined; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold. Control the secondary air damper according to the target secondary air distribution scheme; The control objective also includes: the water-cooled wall near-wall temperature and furnace outlet temperature of the boiler system are lower than a preset second temperature threshold, the second temperature threshold is set according to the ash melting point of the high-alkali fuel, and the second temperature threshold is lower than the first temperature threshold; The configuration process for the several secondary air distribution schemes corresponding to different alkali metal concentration data includes: A combustion prediction model for the boiler system is established, which can provide the flue gas temperature distribution of the boiler system under different operating conditions. For each set of preset operating condition parameters of the boiler system: acquire temperature data corresponding to the operating condition parameter, the temperature data including temperature data of preset measuring points in the combustion zone of the boiler system; continuously adjust the secondary air distribution parameters of the boiler system, the secondary air distribution parameters including the damper opening of the secondary air damper, until the flue gas temperature distribution provided by the combustion prediction model detects that the furnace flame temperature is lower than the first temperature threshold, the water-cooled wall near-wall temperature is lower than the second temperature threshold, and the furnace outlet temperature is lower than the second temperature threshold; record the current secondary air distribution parameters of the boiler system as a secondary air distribution scheme corresponding to the temperature data; configure several secondary air distribution schemes corresponding to different temperature data. Based on the pre-established mapping relationship between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point, the several secondary air distribution schemes corresponding to different temperature data are converted into several secondary air distribution schemes corresponding to different alkali metal concentration data. Establishing the combustion prediction model for the boiler system includes: Acquire several sets of historical data, including: the operating condition parameters of the boiler system, the temperature data of the corresponding preset measuring points, and the temperature data of several measuring points at the furnace outlet of the boiler system. Based on the structural parameters of the boiler system, a boiler structural model is established; Based on the boiler structure model, fluid dynamics simulations are performed according to different operating condition parameters to establish an initial prediction model; the operating condition parameters include: unit load, coal quality, coal mill combination mode, and secondary damper opening. By using the temperature data of the preset measuring points corresponding to each of the operating condition parameters in each group and the temperature data of several measuring points at the furnace outlet, the initial prediction model is corrected to obtain the combustion prediction model of the boiler system.

2. The boiler secondary air distribution control method according to claim 1, characterized in that, The preset location is the slagging area on the water-cooled wall, determined based on the temperature distribution of the boiler system provided by the combustion prediction model.

3. The boiler secondary air distribution control method according to claim 2, characterized in that, The alkali metal concentration sensor uses non-contact spontaneous emission spectroscopy to detect alkali metal concentration.

4. The boiler secondary air distribution control method according to claim 1, characterized in that, The mapping relationship between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point is established through the following steps: Based on the alkali metal concentration data at the preset location and the temperature data at the preset measuring point under different operating conditions, a correlation analysis is performed on the alkali metal concentration and the flue gas temperature, and a correlation function between the alkali metal concentration at the preset location and the flue gas temperature at the preset measuring point is fitted to characterize the mapping relationship.

5. A boiler secondary air distribution control device, used to execute the boiler secondary air distribution control method according to any one of claims 1-4, characterized in that, A boiler system for burning high-alkaline fuels, the boiler system including a secondary air damper, the boiler secondary air distribution control device including: An alkali metal concentration data acquisition unit is used to acquire current alkali metal concentration data, which is data detected by alkali metal concentration sensors arranged at preset positions on the water-cooled walls of the boiler system. The air distribution scheme determination unit is used to determine a target secondary air distribution scheme corresponding to the current alkali metal concentration data from a number of pre-configured secondary air distribution schemes that correspond to different alkali metal concentration data; wherein, the number of secondary air distribution schemes are configured according to a preset control target, the control target including: the furnace flame temperature of the boiler system is lower than a preset first temperature threshold. The damper control unit is used to control the secondary damper according to the target secondary air distribution scheme.

6. A boiler secondary air distribution control system, characterized in that, A boiler system for burning high-alkaline fuels, the boiler system including secondary air dampers, and the boiler secondary air distribution control system including: An alkali metal concentration detection system includes an alkali metal concentration sensor arranged at a preset position on the water-cooled wall of the boiler system, used to detect the current alkali metal concentration data; A boiler secondary air distribution control device includes a memory and a processor; the memory is used to store a program; the processor is used to execute the program to implement the various steps of the boiler secondary air distribution control method as described in any one of claims 1-4.

7. A boiler system, characterized in that, The boiler system uses high-alkaline fuel and includes a secondary air damper and a boiler secondary air distribution control system as described in claim 6.

Images