Power station boiler combustion monitoring system

Abstract

The invention provides a power plant boiler combustion monitoring system comprising a data acquisition module used for acquiring various physical parameters in a boiler combustion process; the data analysis module is used for analyzing the flame temperature gradient, the flue gas oxidability, the fuel-air momentum ratio and the hearth thermal load distribution non-uniformity of all the physical parameters, and four analysis indexes of current boiler combustion are generated; the coking risk assessment module is used for performing fusion calculation on the four analysis indexes through a coking assessment model to determine a coking risk assessment value; the combustion parameter adjusting module is used for calculating ideal adjusting quantity of combustion parameters based on each analysis index when the coking risk assessment value exceeds a preset threshold value so as to reduce the coking risk of the boiler; according to the method, by collecting various physical parameters, building the coking risk assessment model and achieving multi-parameter cooperative adjustment, the safety, stability and economical efficiency of the boiler combustion process are improved, and the boiler coking phenomenon is effectively prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and particularly to a combustion monitoring system for a power plant boiler. Background Art

[0002] With the acceleration of the industrialization process and the continuous growth of social power demand, thermal power generation technology has undergone a long and profound evolution; early thermal power generation technology was relatively simple, mainly relying on traditional coal-fired boilers, with low combustion efficiency, serious energy waste, and relatively large environmental pollution; however, in recent decades, with the continuous progress of technology, thermal power generation technology has made great progress;

[0003] However, in the prior art, some boiler combustion monitoring systems only focus on a few key parameters, such as flame temperature and oxygen content in flue gas, and lack comprehensive and accurate monitoring of important physical parameters such as the details of flame temperature distribution, the momentum ratio of fuel to air, and the uniformity of furnace heat load distribution; this results in the inability to accurately evaluate the true state of the combustion process inside the boiler and makes it difficult to detect potential coking risk factors in advance; at the same time, traditional coking risk assessment methods often rely on simple empirical formulas or single-factor judgments, without comprehensively considering the complex interrelationships between multiple physical parameters; this assessment method has low accuracy and is prone to misjudgment or missed judgment; furthermore, when combustion anomalies are detected, the prior art usually adopts a single adjustment method, such as simply adjusting the air flow or fuel supply; this single adjustment method often cannot fundamentally solve the problem and may even cause other combustion problems;

[0004] Therefore, there is an urgent need in the art for a combustion monitoring system for a power plant boiler to solve the above problems existing in the prior art. Summary of the Invention

[0005] The present invention provides a combustion monitoring system for a power plant boiler, aiming to solve the problems existing in the above prior art. By collecting a variety of physical parameters, constructing a coking risk assessment model, and realizing multi-parameter coordinated adjustment, the safety, stability, and economy of the boiler combustion process are improved, the occurrence of boiler coking is effectively prevented, the requirements of different fuels and working conditions are met, and the overall reliability and adaptability of the system are enhanced.

[0006] The present invention provides a combustion monitoring system for a power plant boiler, comprising:

[0007] A data acquisition module, which is used to collect a variety of physical parameters during the boiler combustion process, including flame temperature distribution data, flue gas composition data, fuel flow data, and air flow data;

[0008] A data analysis module, which is connected to the data acquisition module and is used to analyze the flame temperature gradient, flue gas oxidizing property, fuel-air momentum ratio, and unevenness of furnace heat load distribution of various physical parameters, and generate four analysis indicators for the current boiler combustion;

[0009] A coking risk assessment module, which is connected to the data analysis module and is used to fuse and calculate the four analysis indicators through a coking assessment model to determine the coking risk assessment value;

[0010] A combustion parameter adjustment module, which is connected to the coking risk assessment module and the data analysis module, and is used to calculate the ideal adjustment amount of combustion parameters based on each analysis indicator when the coking risk assessment value exceeds a preset threshold to reduce the coking risk of the boiler; the ideal adjustment amount of the combustion parameters includes the burner angle adjustment value, air flow adjustment value, and fuel flow adjustment value.

[0011] According to a power plant boiler combustion monitoring system provided by the present invention, the data acquisition module includes:

[0012] A flame temperature sensing array, which is composed of temperature sensors distributed at multiple positions in the boiler furnace to form an M*N*P high-precision temperature sensor array for collecting flame temperature distribution data T i,j,k ;

[0013] A flue gas component detection unit, which is used to detect the oxygen content O2% and carbon dioxide content CO2% in the flue gas generated by combustion;

[0014] A fuel flow measurement unit, which is used to obtain the fuel flow rate F participating in combustion in real time f and fuel flow velocity v f ;

[0015] An air flow measurement unit, which is used to obtain the air flow rate F participating in combustion in real time a and air flow velocity v a .

[0016] According to a power plant boiler combustion monitoring system provided by the present invention, the data analysis module includes:

[0017] A temperature gradient analysis unit, which is connected to the flame temperature sensing array and calculates the temperature gradient indicators GT in the x direction, y direction, and z direction of the flame in the furnace based on the flame temperature distribution data T i,j,k Calculate the temperature gradient indicators GT in the x direction, y direction, and z direction of the flame in the furnace based on the flame temperature distribution data T x 、GT y 、GT z ; The calculation formula is:

[0018]

[0019] Among them, Ti+1,j,k -T i,j,k represents the temperature difference between adjacent positions in the x direction, T i,j+1,k -T i,j,k represents the temperature difference between adjacent positions in the y direction, T i,j,k+1 -T i,j,k represents the temperature difference between adjacent positions in the z direction; N*P, M*P, M*N respectively represent the combinations of the number of sensors in the corresponding plane; the temperature gradient index GT x 、GT y 、GT z are used to measure the uniformity of heat transfer of the flame in each direction. The greater the temperature gradient, the higher the probability of forming agglomerates in the local high-temperature area;

[0020] The oxidation analysis unit, which is connected to the flue gas component detection unit, is used to calculate the flue gas oxidation index OI, and the calculation formula is:

[0021]

[0022] Among them, the flue gas oxidation index OI comprehensively reflects the oxidation characteristics of the flue gas. A higher OI value indicates stronger flue gas oxidation, increasing the probability of promoting the oxidation of minerals in the fuel and forming agglomerates;

[0023] The momentum ratio analysis unit, which is connected to the fuel flow measurement unit and the air flow measurement unit, is used to calculate the fuel-air momentum ratio index FAMR, and the calculation formula is:

[0024]

[0025] Among them, the fuel-air momentum ratio index FAMR represents the mixing effect of fuel and air. An inappropriate momentum ratio will lead to incomplete combustion and agglomeration;

[0026] The non-uniformity analysis unit, which is connected to the flame temperature sensing array, calculates the non-uniformity index HLD of the furnace heat load distribution based on the flame temperature distribution data T i,j,k The calculation formula is:

[0027]

[0028] Among them, is the average flame temperature in the furnace, T i,j,k is the temperature data collected by each sensor, and M*N*P is the total number of sensors in the furnace; the non-uniformity index HLD of the furnace heat load distribution is used to evaluate the uniformity of the heat distribution in the furnace. The larger the HLD value, the more uneven the heat load distribution and the higher the agglomeration risk.

[0029] A combustion monitoring system for a power plant boiler provided by the present invention, the coking evaluation model of the coking risk assessment module is as follows:

[0030]

[0031] Wherein, JR is the coking risk assessment value, and the lower its value, the higher the coking probability; GT=(GT x , GT y , GT z ), |GT| is the modulus of GT; FAMR id is the ideal fuel-air momentum ratio determined in advance according to the fuel characteristics and boiler design.

[0032] A combustion monitoring system for a power plant boiler provided by the present invention, the combustion parameter adjustment module includes:

[0033] An adjustment trigger unit, which is connected to the coking risk assessment module, and a coking risk assessment threshold is preset. When the coking risk assessment value JR is lower than this threshold, an adjustment signal is triggered;

[0034] A burner angle adjustment unit, which is connected to the adjustment trigger unit and the temperature gradient analysis unit. When an adjustment signal is detected, the temperature gradient index is judged. When |GT| exceeds the preset threshold GT max , the angle of the burner is adjusted according to the temperature gradient direction;

[0035] A first air flow adjustment unit, which is connected to the adjustment trigger unit and the oxidizing property analysis unit. When an adjustment signal is detected, the first air flow adjustment value is calculated based on the difference between the flue gas oxidizing property index OI and the preset ideal flue gas oxidizing property index value;

[0036] A fuel-air flow coordinated adjustment unit, which is connected to the adjustment trigger unit and the momentum ratio analysis unit. When an adjustment signal is detected, the first fuel flow adjustment value and the second air flow adjustment value are calculated based on the difference between the fuel-air momentum ratio index FAMR and the preset ideal fuel-air momentum ratio index value;

[0037] A fuel-air final flow adjustment unit, which is connected to the first air flow adjustment unit, the fuel-air flow coordinated adjustment unit, the adjustment trigger unit and the non-uniformity analysis unit. When an adjustment signal is detected, the second fuel flow adjustment value is calculated based on the furnace heat load distribution non-uniformity index HLD, the temperature deviation in the area where the burner is located, and the first fuel flow adjustment value; the second fuel flow adjustment value is the finally determined fuel flow adjustment value ΔF fm ; the finally determined air flow adjustment value ΔF a is calculated based on the first air flow adjustment value and the second air flow adjustment value.

[0038] A combustion monitoring system for a power plant boiler provided by the present invention, the calculation process of the burner angle adjustment unit is as follows:

[0039] Δθ x =-K GT *GT x

[0040] Δθ y =-K GT *GT y

[0041] Δθ z =-K GT *GT z

[0042] Wherein, Δθ x 、Δθ y 、Δθ z respectively represent the adjustment angles of the burner in each direction, and K GT is an adjustment coefficient determined according to the boiler characteristics; by adjusting the burner angle, the flame temperature distribution is improved, and the risk of coking in the local high-temperature area is reduced.

[0043] A combustion monitoring system for a power plant boiler provided by the present invention, the calculation process of the first air flow rate adjustment unit is as follows:

[0044] ΔF a1 =-K OI *(OI - OI id )

[0045] Wherein, ΔF a1 is the first air flow rate adjustment value, OI id is the preset ideal flue gas oxidation index value, and K OI is a coefficient related to the boiler combustion characteristics.

[0046] A combustion monitoring system for a power plant boiler provided by the present invention, the calculation process of the fuel-air flow rate coordinated adjustment unit is as follows:

[0047] ΔF f =-K FAMR *(FAMR - FAMR id )*F f

[0048]

[0049] Wherein, ΔF f is the first fuel flow rate adjustment value, ΔF a2 is the second air flow rate adjustment value, and K FAMRis the fuel-air momentum ratio adjustment coefficient, FAMR id is the preset ideal fuel-air momentum ratio target value.

[0050] According to a combustion monitoring system for a power plant boiler provided by the present invention, the calculation process of the fuel and air final flow rate adjustment unit is as follows:

[0051] ΔF fm =-K HLD *HLD*ΔT m *ΔF f

[0052] ΔF a =ω OI ΔF a1 +ω FAMR ΔF a2

[0053] wherein, ΔF a is the finally determined air flow rate adjustment value, ΔF fm is the finally determined fuel flow rate adjustment value, representing the fuel flow rate adjustment amount for the m-th burner; ΔT m is the temperature deviation between the temperature in the area where the burner m is located and the average temperature ; K HLD is the unevenness adjustment coefficient of the furnace heat load distribution; ω OI and ω FAMR are respectively the weights for adjusting the air flow rate according to the flue gas oxidizing property and the weights for adjusting the air flow rate according to the fuel-air momentum ratio, both of which are preset in advance.

[0054] According to a combustion monitoring system for a power plant boiler provided by the present invention, it further includes:

[0055] An execution module, which is connected to the burner angle adjustment unit and the fuel and air final flow rate adjustment unit, and based on the adjustment angles Δθ x , Δθ y , Δθ z , the air flow rate adjustment value ΔF a and the fuel flow rate adjustment value ΔF fm [[ID=6O]]correspondingly adjusts the combustion parameters of the boiler.

[0056] Compared with the prior art, the beneficial effects of the present application are as follows:

[0057] This application can accurately assess the risk of coking. The system can detect potential problems in advance when the coking risk is at a low level and issue a timely warning; this provides operators with ample time to take preventive measures. Compared with existing technologies that often detect coking problems only when they are already serious, this system can effectively prevent damage to the boiler caused by coking, extend the service life of the boiler, reduce maintenance costs, and ensure the safe and stable operation of the boiler.

[0058] The combustion parameter adjustment module calculates the ideal adjustment value of the combustion parameters based on various analysis indicators, achieving coordinated adjustment of the burner angle, air flow rate, and fuel flow rate. The design process fully considers the characteristics of different fuels and various operating conditions. Through precise monitoring and analysis of parameters such as the fuel-air momentum ratio, the ideal value of the combustion parameters can be automatically adjusted according to the type of fuel (such as the volatile matter content of different types of coal). Whether operating at high load, low load, or when switching fuel, the system can quickly adapt to changes in operating conditions, ensuring the stability and efficiency of the combustion process and effectively preventing coking. For example, when using low-volatile fuel, the system can appropriately increase the air flow rate and adjust the burner angle to improve the ignition stability and combustion efficiency of the fuel and reduce the possibility of coking.

[0059] This application achieves more complete combustion of fuel through precise combustion parameter adjustment, thereby reducing fuel waste and improving the thermal efficiency of the boiler; this directly reduces power generation costs and improves the economic benefits of the power plant; and effectively preventing boiler coking helps maintain stable boiler operation, reduces combustion instability and incomplete combustion caused by coking, and thus reduces pollutant emissions.

[0060] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0061] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0063] Figure 1 The diagram is a structural diagram of a power plant boiler combustion monitoring system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0065] Embodiment 1:

[0066] An embodiment of the present invention provides a combustion monitoring system for a power plant boiler. Please refer to Figure 1 , including:

[0067] A data acquisition module, which is used to acquire various physical parameters during the boiler combustion process, including flame temperature distribution data, flue gas composition data, fuel flow data, and air flow data;

[0068] A data analysis module, which is connected to the data acquisition module and is used to perform flame temperature gradient analysis, flue gas oxidizing property analysis, fuel-air momentum ratio analysis, and furnace heat load distribution non-uniformity analysis on various physical parameters to generate four analysis indicators for the current boiler combustion;

[0069] A coking risk assessment module, which is connected to the data analysis module and is used to fuse and calculate the four analysis indicators through a coking assessment model to determine the coking risk assessment value;

[0070] A combustion parameter adjustment module, which is connected to the coking risk assessment module and the data analysis module and is used to calculate the ideal adjustment amount of the combustion parameters based on each analysis indicator when the coking risk assessment value exceeds a preset threshold to reduce the coking risk of the boiler; the ideal adjustment amount of the combustion parameters includes the burner angle adjustment value, the air flow adjustment value, and the fuel flow adjustment value.

[0071] The principle and beneficial effects of this embodiment are as follows: Through real-time monitoring and intelligent control, it ensures that the boiler is always in the best combustion state, improves energy utilization efficiency; the optimized combustion process can reduce harmful gas emissions, which is beneficial to environmental protection; timely adjustment of combustion parameters avoids equipment damage caused by overheating or other adverse conditions, extends the service life of the boiler; reduces the additional costs brought by unplanned shutdowns and frequent maintenance; through effective management of the coking risk, reduces safety hazards caused by slagging and other reasons.

[0072] To further optimize the above embodiment, the data acquisition module includes:

[0073] A flame temperature sensing array, which is composed of temperature sensors distributed at multiple positions in the boiler furnace to form an M*N*P high-precision temperature sensor array for acquiring flame temperature distribution data T i,j,k ;

[0074] A flue gas composition detection unit, which is used to detect the oxygen content O2% and carbon dioxide content CO2% in the flue gas generated by combustion;

[0075] A fuel flow measurement unit for obtaining the fuel flow rate F involved in combustion in real time f and the fuel flow velocity v f ;

[0076] An air flow measurement unit for obtaining the air flow rate F involved in combustion in real time a and the air flow velocity v a .

[0077] It should be noted that the flame temperature sensing array selects thermocouple sensors with high temperature resistance, high precision, and fast response, such as platinum-rhodium-platinum thermocouples (type S) or nickel-chromium-nickel-silicon thermocouples (type K); these thermocouples have good stability and accuracy, can work reliably in a high-temperature environment of up to 1000 °C or more in the boiler furnace, and can quickly and accurately measure the change in flame temperature, with a measurement accuracy of up to ±1 °C or even higher;

[0078] The protective sleeve of the sensor is made of a ceramic material with high temperature resistance and corrosion resistance to ensure that the sensor element is not damaged in a harsh combustion environment (such as high temperature, oxidizing atmosphere, fly ash erosion, etc.), and at the same time ensure good heat conduction performance to accurately measure the flame temperature;

[0079] In terms of layout, a layered and partitioned layout method is adopted, and the sensors are reasonably distributed in the horizontal and vertical directions of the furnace; for example, in the cross-sectional direction of the furnace, the sensors are unevenly distributed at equal intervals or according to the characteristics of heat flow distribution, focusing on areas near the burner, the center of the furnace, and areas where local high temperatures may occur (such as at the flame deflectors); in the vertical direction, the sensors are arranged in layers from the burner area to the furnace outlet to obtain the flame temperature information at different height levels; such a layout can comprehensively and carefully reflect the three-dimensional distribution of the flame temperature in the furnace;

[0080] The detection principles of the flue gas composition detection unit, the fuel flow measurement unit, and the air flow measurement unit belong to the prior art, so they will not be elaborated here.

[0081] To further optimize the above embodiments, the data analysis module includes:

[0082] A temperature gradient analysis unit, which is connected to the flame temperature sensing array and calculates the temperature gradient indexes GT i,j,k of the flame in the x direction, y direction, and z direction in the furnace based on the flame temperature distribution data T x , GT y , GT z ; The calculation formula is:

[0083]

[0084] Among them, T i+1,j,k -T i,j,k represents the temperature difference at adjacent positions in the x direction, and T i,j+1,k -T i,j,k represents the temperature difference at adjacent positions in the y direction, and T i,j,k+1 -T i,j,k represents the temperature difference at adjacent positions in the z direction; N*P, M*P, and M*N respectively represent the combinations of the number of sensors in the corresponding planes; the temperature gradient indicators GT x 、GT y 、GT z are used to measure the uniformity of heat transfer of the flame in each direction. The larger the temperature gradient, the higher the possibility of forming coke in the local high-temperature area;

[0085] The oxidation analysis unit, which is connected to the flue gas composition detection unit, is used to calculate the flue gas oxidation index OI, and the calculation formula is:

[0086]

[0087] Among them, the flue gas oxidation index OI comprehensively reflects the oxidation characteristics of the flue gas. A higher OI value indicates stronger flue gas oxidation, increasing the probability of promoting the oxidation of minerals in the fuel and forming coke;

[0088] The momentum ratio analysis unit, which is connected to the fuel flow measurement unit and the air flow measurement unit, is used to calculate the fuel-air momentum ratio index FAMR, and the calculation formula is:

[0089]

[0090] Among them, the fuel-air momentum ratio index FAMR represents the mixing effect of fuel and air. An inappropriate momentum ratio will lead to incomplete combustion and coke formation;

[0091] The non-uniformity analysis unit, which is connected to the flame temperature sensing array, calculates the non-uniformity index HLD of the furnace heat load distribution based on the flame temperature distribution data T i,j,k The calculation formula is:

[0092]

[0093] Among them, is the average flame temperature in the furnace, T i,j,k is the temperature data collected by each sensor, and M*N*P is the total number of sensors in the furnace; the non-uniformity index HLD of the furnace heat load distribution is used to evaluate the uniformity of the heat distribution in the furnace. The larger the HLD value, the more uneven the heat load distribution and the higher the coke formation risk.

[0094] It should be noted that a large temperature gradient means uneven heat transfer of the flame in the furnace. In areas with a large temperature gradient, heat will quickly accumulate, forming local high-temperature zones. When the values of GT x 、GT y 、GT z are relatively large, it indicates that the temperature changes violently in the corresponding direction, which may cause the fuel particles in this area to heat up rapidly, exceeding their ash melting points, softening the ash and adhering to the heating surface, thereby triggering the coking phenomenon. The uneven temperature distribution will interfere with the stability of the combustion process. The local high-temperature zone may cause the combustion reaction to be too intense, while the combustion in other areas is insufficient, resulting in an irregular and erratic flame shape. This unstable combustion state will cause the residence time of fuel particles in the furnace to be inconsistent, and some unburned fuel particles are likely to adhere to the heating surface, increasing the risk of coking. The existence of high-temperature zones will accelerate the chemical reactions of the minerals in the fuel. At high temperatures, the minerals may undergo phase changes, oxidation and other reactions, forming some compounds with lower melting points, which are more likely to condense and deposit on the heating surface, promoting the growth of coking substances. For example, some alkaline metal oxides may react with other substances at high temperatures to form eutectics with low melting points, thus exacerbating the coking problem.

[0095] A relatively high flue gas oxidation index indicates that the oxygen content in the flue gas is relatively high. In such an oxidizing environment, the minerals in the fuel (such as metal oxides, etc.) are more likely to be oxidized. The oxidized minerals may undergo sintering to form hard coking substances. For example, iron oxides may be further oxidized and combined with other substances in a highly oxidizing atmosphere to form complex oxide structures, which gradually accumulate on the heating surface, resulting in coking.

[0096] The flue gas oxidation will change the physical and chemical properties of the ash. The oxidizing atmosphere may reduce the melting point of the ash, make its fluidity worse, and make it easier to adhere to the heating surface. When the ash cannot be discharged from the furnace smoothly and adheres to parts such as the tube wall, it will continuously accumulate and form a coking layer, affecting the heat transfer efficiency and normal operation of the boiler. Strongly oxidizing flue gas may promote the formation of some corrosive substances, such as sulfur oxides. These corrosive substances will not only corrode the metal of the heating surface, but also react with other components in the ash to form corrosive salts, accelerating the formation and growth of coking substances and causing serious damage to the boiler equipment.

[0097] The fuel-air momentum ratio (FAMR) directly affects the mixing effect of fuel and air. When the FAMR deviates from the ideal value, fuel and air cannot be fully mixed. If the FAMR is too large, the momentum of fuel relative to air is too large, which may cause the fuel to fail to mix with air evenly in time. Part of the fuel will undergo incomplete combustion under an oxygen-deficient state, generating more unburned carbon particles and combustible gases. These substances are likely to deposit on the heating surface and trigger coking. An inappropriate FAMR will change the shape and position of the flame. For example, when the FAMR is too small, the flame may be close to the heating surface, causing the local temperature of the heating surface to be too high and increasing the risk of coking. Moreover, the flame shape may become unstable. The erratic flame will cause local heat load fluctuations on the heating surface, accelerating the formation of coke deposits.

[0098] A large unevenness degree of furnace heat load (HLD) indicates uneven heat distribution in the furnace. In the area with a high heat load, the heating surface receives too much heat, causing the temperature in this area to rise rapidly, resulting in the softening and adhesion of fuel ash at high temperatures and forming coke deposits. For example, in the area near the burner, if the heat load is too high, the fuel burns rapidly here, releasing a large amount of heat, and the heat cannot be evenly diffused in time, which easily leads to coking problems. The uneven heat load will cause thermal stress on the heating surface. Thermal stress may cause damage such as deformation and cracking of the metal material of the heating surface. These damaged parts will become the core points for the attachment of coke deposits. Coke deposits are more likely to deposit and grow on these uneven or damaged surfaces, further exacerbating the deterioration of heat transfer on the heating surface, forming a vicious cycle, and seriously affecting the normal operation of the boiler.

[0099] The uneven heat load distribution will interfere with the stability of the combustion process. Excessive heat load in the burner area may cause the fuel to burn too violently instantaneously, while insufficient heat load in the area far from the burner leads to incomplete combustion. This unstable and incomplete combustion state will generate more unburned substances. These substances deposit on the heating surface and react with other substances, promoting the formation of coke deposits and reducing the combustion efficiency and reliability of the boiler.

[0100] To further optimize the above embodiments, the coking assessment model of the coking risk assessment module is as follows:

[0101]

[0102] Where JR is the coking risk assessment value. The lower its value, the higher the coking probability; GT = (GT x , GT y , GT z ), |GT| is the modulus of GT; FAMR id is the ideal fuel-air momentum ratio determined in advance according to fuel characteristics and boiler design.

[0103] It should be noted that the ideal fuel-air momentum ratio FAMRid The determination needs to comprehensively consider various factors such as fuel characteristics, boiler design, and operating requirements;

[0104] For fuels with high volatile content (such as some high-quality bituminous coals), their volatile matter can be rapidly released and burned at relatively low temperatures, and relatively more air is required to mix with it to ensure complete combustion of the volatile matter; at this time, the ideal fuel-air momentum ratio should be relatively large to enable sufficient mixing of the fuel and air and promote the rapid oxidation reaction of the volatile matter; for example, for bituminous coals with a volatile content of 30%-40%, their FAMR id may be between 0.08 and 0.12 (the values here are only examples and need to be determined according to specific boiler tests);

[0105] On the contrary, for fuels with low volatile content (such as anthracite or lean coal), the release of volatile matter is slow and combustion is relatively difficult, and a more concentrated flame and higher local temperature are required to promote combustion; therefore, the fuel-air momentum ratio should be relatively small to enable the fuel to form a higher concentration with a limited amount of air, increase the local temperature, and facilitate fuel ignition and stable combustion; for example, for lean coal with a volatile content of 10%-15%, its FAMR id may be between 0.05 and 0.08;

[0106] The ash content and ash melting point in the fuel also affect the coking risk and the ideal fuel-air momentum ratio; fuels with high ash content are prone to generating more ash particles during combustion. If the air volume is too large, it will prolong the residence time of the ash particles in the furnace, increasing the probability of ash particles colliding with and depositing on the heating surface, thus leading to coking; for high-ash fuels (such as those with an ash content greater than 30%), the fuel-air momentum ratio should be appropriately reduced and the air volume should be decreased to enable the ash particles to be discharged from the furnace with the flue gas in a shorter time; at the same time, fuels with a lower ash melting point are more likely to form coking substances on the heating surface. At this time, the momentum ratio also needs to be adjusted to control the combustion temperature and atmosphere and avoid local high temperatures causing coking; for example, for fuels with a relatively low ash melting point (softening temperature less than 1200°C) and a high ash content, the FAMR id may be further reduced to the range of 0.04-0.06;

[0107] Different types of burners have different aerodynamic characteristics and different requirements for the fuel-air momentum ratio. For example, a swirl burner promotes the mixing of fuel and air by generating a swirling airflow, and it has a relatively wide adaptability to the fuel-air momentum ratio. However, generally, a suitable momentum ratio range is determined according to its specific swirl intensity and aerodynamic field during design. For a direct current burner, its flame shape and aerodynamic characteristics are different from those of a swirl burner, and the mixing of fuel and air mainly relies on the entrainment effect of the jet. Therefore, it is necessary to more precisely control the fuel-air momentum ratio to ensure the stability and economy of combustion. The arrangement method of the burner in the furnace (such as opposed firing arrangement, tangential firing arrangement, etc.) will also affect the propagation and interaction of the flame, and thus affect the ideal fuel-air momentum ratio. For example, in the case of tangential firing arrangement, in order to ensure good fullness and stable combustion of the flame in the furnace, it is necessary to determine a suitable fuel-air momentum ratio according to factors such as the tangential diameter and burner spacing, generally around 0.06 - 0.10 (the specific value varies according to the boiler design).

[0108] In practical applications, there are more situations. Since the determination method of this value is an existing technical means, it will not be elaborated one by one here.

[0109] To further optimize the above embodiments, the combustion parameter adjustment module includes:

[0110] An adjustment trigger unit, which is connected to the sintering risk assessment module, pre-sets a sintering risk assessment threshold, and when the sintering risk assessment value JR is lower than this threshold, triggers an adjustment signal;

[0111] A burner angle adjustment unit, which is connected to the adjustment trigger unit and the temperature gradient analysis unit. When an adjustment signal is detected, it determines the temperature gradient index. When |GT| exceeds the preset threshold GT max , adjusts the angle of the burner according to the temperature gradient direction;

[0112] A first air flow adjustment unit, which is connected to the adjustment trigger unit and the oxidizing property analysis unit. When an adjustment signal is detected, it calculates a first air flow adjustment value based on the difference between the flue gas oxidizing property index OI and the preset ideal flue gas oxidizing property index value;

[0113] A fuel-air flow coordinated adjustment unit, which is connected to the adjustment trigger unit and the momentum ratio analysis unit. When an adjustment signal is detected, it calculates a first fuel flow adjustment value and a second air flow adjustment value based on the difference between the fuel-air momentum ratio index FAMR and the preset ideal fuel-air momentum ratio index value;

[0114] The final fuel and air flow regulation unit is connected to the first air flow regulation unit, the fuel and air flow coordinated regulation unit, the regulation trigger unit, and the unevenness analysis unit. When a regulation signal is detected, it calculates the second fuel flow regulation value based on the unevenness index HLD of the furnace heat load distribution, the temperature deviation in the area where the burner is located, and the first fuel flow regulation value; the second fuel flow regulation value is the finally determined fuel flow regulation value ΔF fm ; calculates the finally determined air flow regulation value ΔF based on the first air flow regulation value and the second air flow regulation value a .

[0115] It should be noted that the calculation process of the burner angle regulation unit is as follows:

[0116] Δθ x =-K GT *GT x

[0117] Δθ y =-K GT *GT y

[0118] Δθ z =-K GT *GT z

[0119] where, Δθ x , Δθ y , Δθ z respectively represent the adjustment angles of the burner in each direction, and K GT is the adjustment coefficient determined according to the boiler characteristics; by adjusting the burner angle, the flame temperature distribution is improved, and the risk of coking in the local high-temperature area is reduced.

[0120] The value of the adjustment coefficient K GT needs to comprehensively consider various characteristics of the boiler. The following are the main steps and factors for its determination:

[0121] The different thermal conductivities of the materials used in the furnace (such as refractory bricks, water-cooled wall tube materials, etc.) will affect the heat transfer and distribution in the furnace; if the furnace material has good thermal conductivity, the heat can be quickly and evenly transferred to the heating surface, and the influence of the flame temperature gradient on the heating surface temperature is relatively small. At this time, K GT can take a smaller value, such as 0.05 - 0.1; on the contrary, if the furnace material has poor thermal conductivity, the change of the flame temperature gradient will more significantly affect the heating surface temperature, easily leading to local overheating and coking, and K GT needs to take a larger value, probably between 0.1 - 0.2, to enhance the adjustment effect on the burner angle and better control the flame temperature distribution;

[0122] The structure of the heating surface (such as smooth tubes, finned tubes, etc.) and the arrangement method (such as close arrangement, sparse arrangement, etc.) will affect the heat absorption efficiency and the uniformity of temperature distribution; a heating surface with a close arrangement and a complex structure can absorb heat more effectively, but is more susceptible to the influence of the flame temperature gradient. In this case, in order to prevent excessive local thermal stress and coking, K GT should take a relatively large value, such as 0.15 - 0.25; for a boiler with a relatively sparse arrangement of the heating surface and a simple structure, the heat distribution is relatively uniform, and K GT can be appropriately reduced, with a value range of about 0.08 - 0.15;

[0123] The adjustment ability of the burner itself (such as the angle adjustment range, adjustment accuracy, etc.) has an important influence on the value of K GT ; if the burner has a large angle adjustment range (such as ±30° or larger) and high adjustment accuracy (such as being able to be accurate to ±1°), then K GT can take a relatively large value to make full use of the adjustment ability of the burner to optimize the flame temperature distribution; for example, in this case, it may be between 0.1 - 0.3; on the contrary, if the burner adjustment range is limited (such as ±15°) and the accuracy is low (such as only being able to be accurate to ±3°), K GT should take a smaller value to prevent unstable combustion caused by too large an adjustment amplitude, and the value may be in the range of 0.05 - 0.15;

[0124] Different types of burners (such as swirl burners, tangential burners, etc.) produce different flame shapes and aerodynamic characteristics, and have different requirements for K GT ; the swirling flame produced by the swirl burner is relatively sensitive to changes in the burner angle, and a small angle adjustment may cause large changes in the flame shape and temperature distribution. Therefore, K GT takes a relatively small value, generally between 0.08 - 0.15; the flame shape and temperature distribution of the tangential burner are relatively less affected by the burner angle, but in order to achieve a better temperature adjustment effect, K GT also needs to be determined according to its specific characteristics, and may be about 0.1 - 0.2;

[0125] Collect the operation history data of the boiler under different working conditions, including the changes in the flame temperature gradient, the records of burner angle adjustments, and the coking situation, etc.; through the statistical analysis of these data, find out the quantitative relationship between the flame temperature gradient and the coking risk, as well as the actual effect of burner angle adjustment on improving the temperature distribution and preventing coking; for example, if the historical data shows that when the flame temperature gradient changes by a certain value, the coking risk increases significantly, and specific burner angle adjustments can effectively reduce the coking risk, then K can be determined according to these data GTThe approximate value range is such that it can timely and effectively adjust the burner angle during actual operation to prevent coking;

[0126] During the actual operation of the boiler, conduct on-site tests and gradually change K GT value, observe the changes in flame temperature distribution, combustion stability, and coking conditions; start the test from a relatively small K GT value, such as 0.05, and then gradually increase it. After each adjustment, operate stably for a period of time, measure and record relevant parameters; by comparing the test results under different K GT values, find the optimal K GT value that can keep the boiler stably burning under various working conditions, with a uniform flame temperature distribution and the lowest coking risk; this on-site test and optimization adjustment process may need to be repeated multiple times, and various working conditions such as different loads and different fuels should be considered to ensure that the determined value has wide applicability and effectiveness; for example, after a series of tests, it is found that when K GT = 0.12, the flame temperature distribution is relatively ideal during both high-load and low-load operations of the boiler, and the coking phenomenon is effectively controlled. Then this value can be used as the K GT standard value for this boiler and be fine-tuned according to the actual situation during subsequent operations;

[0127] To further optimize the above embodiments, the calculation process of the first air flow regulation unit is:

[0128] ΔF a1 = -K OI *(OI - OI id )

[0129] where, ΔF a1 is the first air flow regulation value, OI id is the preset ideal flue gas oxidizing index value, and K OI is a coefficient related to the combustion characteristics of the boiler.

[0130] The calculation process of the fuel and air flow coordinated regulation unit is:

[0131] ΔF f = -K FAMR *(FAMR - FAMR id )*F f

[0132]

[0133] where, ΔF f is the first fuel flow regulation value, ΔF a2 is the second air flow regulation value, K FAMR is the fuel-air momentum ratio regulation coefficient, FAMRid is the preset ideal fuel-air momentum ratio index value.

[0134] It should be noted that the coefficient K related to the combustion characteristics of the boiler OI and the fuel-air momentum ratio adjustment coefficient K FAMR need to be determined by considering multiple factors, which are briefly described as follows:

[0135] The chemical compositions and combustion characteristics of different fuels vary. For example, fuels with high volatile matter have a fast combustion rate and are sensitive to changes in air volume. When determining K OI , it is necessary to consider their combustion stability and pollutant generation characteristics under different oxygen contents. For bituminous coal with high volatile matter, the value of K OI may be relatively small to prevent excessive adjustment of the air flow from affecting combustion stability, and the value range may be between 0.2 - 0.4. For fuels with low volatile matter, to ensure complete combustion, K OI may be between 0.4 - 0.6 to ensure effective adjustment of the air flow to adapt to the fuel characteristics.

[0136] The ash and sulfur contents of the fuel affect K FAMR . For fuels with high ash content, a more reasonable fuel-air momentum ratio is required during combustion to avoid ash deposition and coking. The value of K FAMR should be such that the fuel and air are well mixed, and it may be between 1.5 - 2.5. For fuels with high sulfur content, special requirements are placed on the air volume and mixing effect during combustion, and K FAMR also needs to be adjusted accordingly to control combustion products and prevent corrosion, and its value may be around 1.2 - 2.0.

[0137] At the same time, through research on the empirical data of the coefficient values of boilers of the same type, scale, and in good operation, understand the coefficient settings under similar fuel characteristics, boiler structures, and operating conditions, and use them as a reference range for determining the coefficients of this boiler.

[0138] To further optimize the above embodiments, the calculation process of the fuel and air final flow rate adjustment unit is as follows:

[0139] ΔF fm =-K HLD *HLD*ΔT m *ΔF f

[0140] ΔF a =ω OI ΔF a1 +ω FAMR ΔF a2

[0141] Among them, ΔF a is the finally determined air flow rate adjustment value, ΔF fmis the finally determined fuel flow rate adjustment value, representing the fuel flow rate adjustment amount for the m-th burner; ΔT m is the temperature deviation between the temperature in the area where burner m is located and the average temperature ; K HLD is the unevenness adjustment coefficient of the furnace heat load distribution; ω OI and ω FAMR are respectively the weights for adjusting the air flow rate according to the flue gas oxidizing property and the weights for adjusting the air flow rate according to the fuel-air momentum ratio, both of which are preset in advance.

[0142] It should be noted that the determination of the weights for adjusting the air flow rate according to the flue gas oxidizing property and the weights for adjusting the air flow rate according to the fuel-air momentum ratio is based on empirical settings. If it is considered that the flue gas oxidizing property adjustment and the fuel-air momentum ratio adjustment are equally important, then the two weights are equal, that is, ω OI = ω FAMR = 0.5.

[0143] In order to further optimize the above embodiments, it further includes:

[0144] An execution module, which is connected to the burner angle adjustment unit and the final fuel and air flow rate adjustment unit, and based on the adjustment angles Δθ x , Δθ y , Δθ z , the air flow rate adjustment value ΔF a and the fuel flow rate adjustment value ΔF fm correspondingly adjust the combustion parameters of the boiler.

[0145] It should be noted that the execution module is implemented by existing control equipment.

[0146] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A combustion monitoring system for a power plant boiler, characterized in that, Comprising: A data acquisition module, which is used to acquire a variety of physical parameters during the boiler combustion process, including flame temperature distribution data, flue gas composition data, fuel flow data, and air flow data; A data analysis module, which is connected to the data acquisition module and is used to perform flame temperature gradient analysis, flue gas oxidizing property analysis, fuel-air momentum ratio analysis, and unevenness analysis of furnace heat load distribution on various physical parameters to generate four analysis indicators for the current boiler combustion; A coking risk assessment module, which is connected to the data analysis module and is used to fuse and calculate the four analysis indicators through a coking assessment model to determine the coking risk assessment value; A combustion parameter adjustment module, which is connected to the coking risk assessment module and the data analysis module and is used to calculate the ideal adjustment amount of combustion parameters based on each analysis indicator to reduce the coking risk of the boiler when the coking risk assessment value exceeds a preset threshold; the ideal adjustment amount of the combustion parameters includes burner angle adjustment value, air flow adjustment value, and fuel flow adjustment value.

2. The combustion monitoring system for a power plant boiler according to claim 1, characterized in that, The data acquisition module includes: A flame temperature sensing array, which is composed of temperature sensors distributed at multiple positions in the boiler furnace, forms an M*N*P high-precision temperature sensor array for collecting flame temperature distribution data T i,j,k ; A flue gas composition detection unit, which is used to detect the oxygen content O2% and carbon dioxide content CO2% in the flue gas generated by combustion; A fuel flow measurement unit for obtaining in real time the fuel flow rate F involved in combustion f and the fuel flow velocity v f ; An air flow measurement unit for obtaining in real time the air flow rate F involved in combustion a and the air flow velocity v a .

3. The combustion monitoring system for a power plant boiler according to claim 2, characterized in that, The data analysis module includes: A temperature gradient analysis unit, which is connected to the flame temperature sensing array and calculates temperature gradient indicators GT i,j,k of the flame in the x-direction, y-direction, and z-direction in the furnace based on the flame temperature distribution data T x , GT y , GT z ; The calculation formula is: Among them, T i+1,j,k -T i,j,k represents the temperature difference between adjacent positions in the x direction, T i,j+1,k -T i,j,k represents the temperature difference between adjacent positions in the y direction, T i,j,k+1 -T i,j,k represents the temperature difference between adjacent positions in the z direction; N*P, M*P, and M*N respectively represent the combinations of the number of sensors in the corresponding planes; the temperature gradient indicators GT x 、GT y 、GT z are used to measure the uniformity of heat transfer of the flame in each direction. The larger the temperature gradient, the higher the possibility of coking in the local high-temperature area; An oxidizing property analysis unit, which is connected to the flue gas composition detection unit and is used to calculate the flue gas oxidizing property index OI, and the calculation formula is: Among them, the flue gas oxidizing property index OI comprehensively reflects the oxidation characteristics of the flue gas. A higher OI value indicates stronger flue gas oxidizing property, increasing the probability of promoting the oxidation of minerals in the fuel and forming coking substances; A momentum ratio analysis unit, which is connected to the fuel flow measurement unit and the air flow measurement unit and is used to calculate the fuel-air momentum ratio index FAMR, and the calculation formula is: Among them, the fuel-air momentum ratio index FAMR represents the mixing effect of fuel and air. An inappropriate momentum ratio will lead to incomplete combustion and coking; The non-uniformity analysis unit, which is connected to the flame temperature sensing array, calculates the non-uniformity index HLD of the furnace heat load distribution based on the flame temperature distribution data T i,j,k The calculation formula is as follows: Among them, is the average flame temperature in the furnace, T i,j,k is the temperature data collected by each sensor, and M*N*P is the total number of sensors in the furnace; the unevenness index HLD of the furnace heat load distribution is used to evaluate the degree of uniformity of the heat distribution in the furnace. The larger the HLD value, the more uneven the heat load distribution and the higher the coking risk.

4. The combustion monitoring system for a power plant boiler according to claim 3, wherein, The coking assessment model of the coking risk assessment module is: Among them, JR is the coking risk assessment value. The lower its value, the higher the coking probability; GT = (GT x , GT y , GT z ), |GT| is the modulus of GT; FAMR id is the ideal fuel-air momentum ratio pre-determined according to fuel characteristics and boiler design.

5. A power plant boiler combustion monitoring system according to claim 4, characterized in that, The combustion parameter adjustment module includes: An adjustment trigger unit, which is connected to the coking risk assessment module and preset a coking risk assessment threshold. When the coking risk assessment value JR is lower than this threshold, it triggers an adjustment signal; The burner angle adjustment unit, which is connected to the adjustment trigger unit and the temperature gradient analysis unit, determines the temperature gradient index when an adjustment signal is detected, and adjusts the angle of the burner according to the temperature gradient direction when |GT| exceeds a preset threshold. max , and adjusts the angle of the burner according to the temperature gradient direction; A first air flow adjustment unit, which is connected to the adjustment trigger unit and the oxidizing property analysis unit. When the adjustment signal is detected, it calculates the first air flow adjustment value based on the difference between the flue gas oxidizing property index OI and the preset ideal flue gas oxidizing property index value; A fuel-air flow coordinated adjustment unit, which is connected to the adjustment trigger unit and the momentum ratio analysis unit. When the adjustment signal is detected, it calculates the first fuel flow adjustment value and the second air flow adjustment value based on the difference between the fuel-air momentum ratio index FMAR and the preset ideal fuel-air momentum ratio index value; The final fuel and air flow regulation unit, which is connected to the first air flow regulation unit, the fuel and air flow coordinated regulation unit, the regulation trigger unit, and the non-uniformity analysis unit. When a regulation signal is detected, it calculates the second fuel flow regulation value based on the non-uniformity index HLD of the furnace heat load distribution, the temperature deviation in the area where the burner is located, and the first fuel flow regulation value; the second fuel flow regulation value is the finally determined fuel flow regulation value ΔF fm ; calculates the finally determined air flow regulation value ΔF based on the first air flow regulation value and the second air flow regulation value a .

6. The combustion monitoring system for a power plant boiler according to claim 5, characterized in that, The calculation process of the burner angle adjustment unit is: Δθ x = -K GT *GT x Δθ y = -K GT *GT y Δθ z = -K GT *GT z Among them, Δθ x , Δθ y , Δθ z respectively represent the adjustment angles of the burner in each direction, and K GT is an adjustment coefficient determined according to the boiler characteristics; by adjusting the burner angle, the flame temperature distribution can be improved and the risk of coking in the local high-temperature area can be reduced.

7. A power plant boiler combustion monitoring system according to claim 6, characterized in that, The calculation process of the first air flow adjustment unit is: ΔF a1 = -K OI *(OI - OI id ) Among them, ΔF a1 is the first air flow regulation value, OI id is the preset ideal flue gas oxidizing index value, K OI is a coefficient related to the boiler combustion characteristics.

8. A power plant boiler combustion monitoring system according to claim 7, characterized in that, The calculation process of the fuel-air flow coordinated adjustment unit is: Δf f = -K FAMR *(FAMR - FAMR id )*F f where, ΔF f is the first fuel flow rate adjustment value, and ΔF a2 is the second air flow rate adjustment value, K FAMR is the fuel-air momentum ratio adjustment coefficient, and FAMR id is the preset ideal fuel-air momentum ratio target value.

9. A power plant boiler combustion monitoring system according to claim 8, characterized in that, The calculation process of the final fuel-air flow adjustment unit is: ΔF fm =-K HLD *HLD*ΔT m *ΔF f ΔF a = ω OI ΔF a1 + ω FAMR ΔF a2 Among them, ΔF a is the finally determined air flow rate adjustment value, and ΔF fm is the finally determined fuel flow rate adjustment value, representing the fuel flow rate adjustment amount for the m-th burner; ΔT m is the temperature deviation between the temperature of the area where the burner m is located and the average temperature ; K HLD is the adjustment coefficient of the unevenness of the furnace heat load distribution; ω OI and ω FAMR are respectively the weights for adjusting the air flow rate according to the flue gas oxidizing property and the weights for adjusting the air flow rate according to the fuel-air momentum ratio, both of which are preset.

10. A power plant boiler combustion monitoring system according to claim 9, characterized in that, It also includes: An execution module, which is connected to the burner angle adjustment unit and the final fuel and air flow rate adjustment unit, and adjusts the combustion parameters of the boiler based on the adjustment angles Δθ x , Δθ y , Δθ z , the air flow rate adjustment value ΔF a and the fuel flow rate adjustment value ΔF fm correspondingly.

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