Method and equipment for quantitatively calculating thickness of ash deposition layer based on excess air coefficient

Abstract

The invention discloses a method and equipment for quantitatively calculating the thickness of an ash deposition layer based on an excess air coefficient, and belongs to the technical field of thermal equipment performance diagnosis. According to the method for quantitatively calculating the ash deposition layer thickness based on the excess air coefficient, the influence of the excess air coefficient change on multiple indirect parameters such as the theoretical combustion temperature of a hearth, the smoke temperature of a hearth outlet, the average heat effective coefficient of a water cooling wall, the average temperature of hearth flame and the average temperature of an ash dirt layer of a slagging water cooling wall tube is comprehensively considered; an accurate mathematical model is established; the mathematical model is established based on the excess air coefficient, the variability of working conditions is fully considered, the internal relation between the excess air coefficient and the ash deposition degree of the water-cooled wall can be accurately revealed, and a solid theoretical basis and a scientific basis are provided for ash deposition diagnosis of the hearth water-cooled wall, so that the accurate calculation of the ash deposition layer of the hearth water-cooled wall is realized; and powerful support is provided for safe and economical operation of the power station boiler.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal equipment performance diagnosis, and in particular to a method and a device for quantitatively calculating the thickness of a dust accumulation layer based on an excess air coefficient. Background Art

[0002] Domestic power station boilers generally use coal as their main fuel. During the operation of coal-fired boilers, ash pollution will inevitably appear on various parts of the furnace heating surface. The formation of ash pollution poses a serious threat to the safety and economy of power station boilers. Specifically, the ash layer on the water-cooled wall of the furnace will cause its heat transfer efficiency to drop significantly, and the heat absorption of the furnace will decrease accordingly, which will cause an abnormal increase in the flue gas temperature at the furnace outlet. In extreme cases, it may also block the economizer, air preheater and flue gas channel, resulting in deterioration of heat transfer conditions, increased flue gas resistance, a sharp rise in exhaust gas temperature, forced increase in induced draft fan output, and increased power consumption; if the ash accumulation problem of the water-cooled wall of the furnace continues to worsen, it may even force the superheater temperature to exceed the limit, causing serious accidents such as pipe bursts.

[0003] In view of the significant impact of the ash layer on the furnace water-cooled wall on the safe operation of the unit, accurate diagnosis of the ash layer on the furnace water-cooled wall is particularly important. Unfortunately, there is currently no mature method for quantitatively calculating the thickness of the ash layer on the furnace water-cooled wall that is suitable for changes in operating conditions. The currently commonly used method is to perform indirect calculations based on the ash pollution empirical coefficient obtained under specific conditions, but this method has a fundamental limitation: the ash pollution empirical coefficient cannot be adjusted accordingly according to the real-time fluctuations of the actual operating conditions. Therefore, under different operating environments, the ash layer thickness data obtained using existing indirect measurement methods is often difficult to accurately reflect the actual situation.

[0004] Therefore, it is urgent to develop a new method that is suitable for changes in operating conditions and can indirectly and accurately quantitatively calculate the ash layer on the furnace water-cooled wall only through the operating parameters of the boiler. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for quantitatively calculating the thickness of the ash layer based on the excess air coefficient, aiming to solve the limitation of the current technology that indirect measurement means cannot accurately capture the actual dynamic changes of the thickness of the ash layer on the furnace water-cooled wall under different operating environments.

[0006] The present invention solves the above technical problems through the following technical solutions: A method for quantitatively calculating the thickness of a dust accumulation layer based on an excess air coefficient comprises the following steps: Step 1: Based on the relationship between the excess air coefficient and the theoretical combustion temperature, establish an empirical formula for the theoretical combustion temperature according to the heat balance method; establish a calculation formula for the flue gas temperature at the furnace outlet according to the furnace thermal calculation method, and derive a calculation formula for the average heat effective coefficient of the water wall; list the calculation formula for the heat absorption of the water wall and the relationship equation between the average heat effective coefficient of the water wall and the heat absorption of the water wall, and combine with the calculation formula for the average heat effective coefficient of the water wall to derive a calculation formula for the average projected heat flux of the flame; list the definition formula for the average projected heat flux of the flame, and combine with the calculation formula for the average projected heat flux of the flame to derive a calculation formula for the average temperature of the furnace flame; based on the radiation heat transfer equation between the furnace flame and the water wall, establish a calculation formula for the heat absorption of the water wall per unit furnace wall, and derive a calculation formula for the average temperature of the fouling layer of the slagging water wall tube; based on the saturation water temperature in the water wall tube changing with the excess air coefficient and the theoretical combustion temperature, list the calculation formula for the saturation water temperature in the water wall tube. Step 2: Obtain the relative position of the flame center and calculate the influence parameters of the flame center on the furnace heat transfer; obtain the boiler operation parameters, and combine with the influence parameters of the flame center on the furnace heat transfer. Based on the empirical formula for the theoretical combustion temperature, the calculation formula for the average heat effective coefficient of the water wall, the calculation formula for the average temperature of the furnace flame, the calculation formula for the average temperature of the fouling layer of the slagging water wall tube, the calculation formula for the heat absorption of the water wall per unit furnace wall, and the calculation formula for the saturation water temperature in the water wall tube, calculate the theoretical combustion temperature, the average heat effective coefficient of the water wall, the average temperature of the furnace flame, the average temperature of the fouling layer of the slagging water wall tube, the heat absorption of the water wall per unit furnace wall, and the saturation water temperature in the water wall tube respectively. Step 3: List the formula for the average thickness of the ash deposit layer on the furnace water wall, and calculate the average thickness of the ash deposit layer on the furnace water wall based on the average temperature of the fouling layer of the slagging water wall tube, the heat absorption of the water wall per unit furnace wall, and the saturation water temperature in the water wall tube.

[0007] A further improvement of the present invention is that the empirical formula for the theoretical combustion temperature is specifically:

[0008] Wherein, is the theoretical combustion temperature; is the effective heat brought into the furnace per kilogram of fuel; is the actual flue gas enthalpy at 1800°C; is the actual flue gas enthalpy at 2000°C; is the actual flue gas enthalpy at 1600°C.

[0009] A further improvement of the present invention is that the calculation formula for the flue gas temperature at the furnace outlet is specifically:

[0010] Wherein, is the flue gas temperature at the furnace outlet; M is the influence parameter of the flame center on furnace heat transfer; is the furnace emissivity; is the average heat effective coefficient of the water wall; is the furnace wall area.

[0011] A further improvement of the present invention lies in that the calculation formula for the average heat effective coefficient of the water wall is specifically: .

[0012] A further improvement of the present invention lies in that the calculation formula for the average temperature of the furnace flame is specifically:

[0013] wherein, is the average temperature of the furnace flame.

[0014] A further improvement of the present invention lies in that the calculation formula for the heat absorption of the water wall per unit furnace wall is specifically:

[0015] wherein, is the heat absorption of the water wall per unit furnace wall; is the black body radiation constant; is the average temperature of the fouling layer of the slagging water wall tubes.

[0016] A further improvement of the present invention lies in that the calculation formula for the average temperature of the fouling layer of the slagging water wall tubes is specifically:

[0017] wherein, is the heat absorption of the water wall.

[0018] A further improvement of the present invention lies in that the calculation formula for the saturation water temperature in the water wall tubes is specifically:

[0019] wherein, is the water and steam temperature - pressure function for temperature conversion from the enthalpy value at the pressure; is the enthalpy value of the working medium at the economizer inlet; is the enthalpy value at the economizer intermediate point; is the economizer inlet pressure at the rated load.

[0020] A further improvement of the present invention lies in that the formula for the average thickness of the ash deposit layer on the furnace water wall is specifically:

[0021] wherein, is the thermal conductivity of the ash fouling layer, is the average thickness of the ash deposit layer on the furnace water wall.

[0022] The present invention also provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the method for quantitatively calculating the thickness of the ash deposit layer based on the excess air coefficient are implemented.

[0023] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The method for quantitatively calculating the thickness of the ash deposit layer based on the excess air coefficient provided by the present invention establishes an accurate mathematical model by comprehensively considering the effects of changes in the excess air coefficient on multiple indirect parameters such as the theoretical combustion temperature in the furnace, the flue gas temperature at the furnace outlet, the average thermal effectiveness coefficient of the water wall, the average temperature of the furnace flame, and the average temperature of the ash fouling layer on the slagging water wall tubes. This mathematical model is established based on the excess air coefficient, fully considering the variability of working conditions, and can accurately reveal the internal relationship between the excess air coefficient and the degree of ash deposition on the water wall, providing a solid theoretical basis and scientific basis for the ash deposition diagnosis of the furnace water wall, thereby realizing the accurate calculation of the ash deposit layer on the furnace water wall and providing strong support for the safe and economic operation of power station boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0025] Figure 1 is a schematic flow chart of a method for quantitatively calculating the change in the thickness of the ash deposit with the change in the excess air coefficient according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown herein can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention claimed, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0028] The following further elaborates on the present invention in conjunction with the accompanying drawings and specific embodiments, which is an explanation rather than a limitation of the present invention.

[0029] See Figure 1 , a method for quantitatively calculating the thickness of the ash deposit layer based on the excess air coefficient, comprising the following steps: Step 1: Based on the relationship between the excess air coefficient and the theoretical combustion temperature, establish an empirical formula for the theoretical combustion temperature according to the heat balance method; establish a calculation formula for the flue gas temperature at the furnace outlet based on the furnace thermal calculation method, and derive a calculation formula for the average heat transfer effective coefficient of the water wall; list the calculation formula for the heat absorption of the water wall and the relationship equation between the average heat transfer effective coefficient of the water wall and the heat absorption of the water wall, and combine with the calculation formula for the average heat transfer effective coefficient of the water wall to derive a calculation formula for the average projected heat flux of the flame; list the definition formula for the average projected heat flux of the flame, and combine with the calculation formula for the average projected heat flux of the flame to derive a calculation formula for the average temperature of the furnace flame; based on the radiation heat transfer equation between the furnace flame and the water wall, establish a calculation formula for the heat absorption of the water wall per unit furnace wall, and derive a calculation formula for the average temperature of the ash fouling layer of the slagging water wall tube; based on the saturation water temperature in the water wall tube varying with the excess air coefficient and the theoretical combustion temperature, list the calculation formula for the saturation water temperature in the water wall tube; Step 2: Obtain the relative position of the flame center and calculate the influence parameter of the flame center on the furnace heat transfer; obtain the boiler operation parameters, and combine with the influence parameter of the flame center on the furnace heat transfer. Based on the empirical formula for the theoretical combustion temperature, the calculation formula for the average heat transfer effective coefficient of the water wall, the calculation formula for the average temperature of the furnace flame, the calculation formula for the average temperature of the ash fouling layer of the slagging water wall tube, the calculation formula for the heat absorption of the water wall per unit furnace wall, and the calculation formula for the saturation water temperature in the water wall tube, calculate the theoretical combustion temperature, the average heat transfer effective coefficient of the water wall, the average temperature of the furnace flame, the average temperature of the ash fouling layer of the slagging water wall tube, the heat absorption of the water wall per unit furnace wall, and the saturation water temperature in the water wall tube respectively; Step 3: List the formula for the average thickness of the ash deposit layer on the furnace water wall, and calculate the average thickness of the ash deposit layer on the furnace water wall based on the average temperature of the ash fouling layer of the slagging water wall tube, the heat absorption of the water wall per unit furnace wall, and the saturation water temperature in the water wall tube.

[0030] The quantitative calculation method for the change of the excess air coefficient affecting the ash fouling thickness provided by the present invention comprehensively considers the influence of the change of the excess air coefficient on multiple indirect parameters such as the theoretical combustion temperature in the furnace, the flue gas temperature at the furnace outlet, the average heat effective coefficient of the water wall, the average temperature of the furnace flame, and the average temperature of the ash fouling layer on the slagging water wall tubes, and establishes an accurate mathematical model, which can accurately reflect the internal relationship between the excess air coefficient and the ash fouling degree of the water wall, provides a solid theoretical basis and scientific basis for the ash fouling diagnosis of the furnace water wall, thereby realizing the accurate calculation of the ash fouling layer on the furnace water wall, overcomes the limitations such as relying on complex detection equipment, difficult direct measurement, and susceptibility to interference in the prior art, and provides strong support for the safe and economic operation of power station boilers.

[0031] This method is based on the following concepts: 1. When the excess air coefficient rises, based on the principle of heat balance, various heat losses change, the theoretical combustion temperature drops, and the flue gas temperature at the furnace outlet drops. Therefore, it is proved that an increase in the excess air coefficient may reduce the ash fouling thickness of the furnace, but the influence of other factors such as load and coal type changes cannot be excluded. 2. The average heat effective coefficient of the furnace water wall is affected by the flue gas temperature at the furnace outlet. The smaller the average heat effective coefficient of the water wall, the more serious the ash fouling degree of the water wall. Through the relationship between the average heat effective coefficient of the water wall, the heat absorption of the water wall, and the average heat flux of the flame, the change of the average temperature of the flame with the excess air coefficient and the flue gas temperature at the furnace outlet can be obtained. 3. From the average temperature of the flame and the radiation heat transfer equation between the furnace flame and the water wall, the parameters required for calculating the ash fouling thickness can be obtained: the average temperature of the ash fouling layer on the slagging water wall tubes. Then, combined with the thermal conductivity of the ash fouling layer and the saturated water temperature in the tube that changes with the excess air coefficient, etc., the average thickness of the ash fouling on the water wall can be calculated.

[0032] Based on the above concepts, according to the characteristics before and after the change of the excess air coefficient of the boiler, and based on the heat balance theory, radiation heat transfer equation, etc., the principle followed to implement the technical solution of the present invention can be further proposed, that is: 1. As the excess air coefficient increases, various heat losses in the furnace change continuously, causing the theoretical combustion temperature in the furnace to drop and the heat loss of exhaust gas to increase, indicating that its heat transfer efficiency decreases, which may cause the ash fouling of the furnace water wall. However, the decrease in the flue gas temperature at the furnace outlet means that although there is an ash fouling phenomenon, the ash fouling thickness may decrease. 2. As the flue gas temperature at the furnace outlet decreases, the average heat effective coefficient of the water wall for judging the ash fouling degree of the furnace rises, proving that the ash fouling degree of the water wall is reduced. The change of the average temperature of the flame can be calculated from the relationship between the average heat effective coefficient of the water wall, the heat absorption of the water wall, and the average heat flux of the flame. 3. Since there is a radiative heat transfer relationship between the furnace flame and the water wall, after obtaining the change result of the average flame temperature, the average temperature of the fouling layer on the slagging water wall tube can also be obtained. Then, the average thickness of the ash deposit on the water wall can be obtained by integrating coefficients such as the fouling layer thermal conductivity and the saturated water temperature inside the tube, thereby judging the ash deposit situation on the water wall.

[0033] Specifically, the empirical formula for the theoretical combustion temperature is as follows:

[0034] Among them, is the theoretical combustion temperature; is the effective heat brought into the furnace per kilogram of fuel; is the actual flue gas enthalpy at 1800°C; is the actual flue gas enthalpy at 2000°C; is the actual flue gas enthalpy at 1600°C.

[0035] Specifically, the calculation formula for the flue gas temperature at the furnace outlet is as follows:

[0036] Among them, is the flue gas temperature at the furnace outlet; M is the influence parameter of the flame center on the heat transfer in the furnace; is the furnace emissivity; is the average heat effective coefficient of the water wall; is the furnace wall area.

[0037] Specifically, the calculation formula for the average heat effective coefficient of the water wall is as follows: .

[0038] Specifically, the calculation formula for the average temperature of the furnace flame is as follows:

[0039] Among them, is the average temperature of the furnace flame.

[0040] Specifically, the calculation formula for the heat absorption of the water wall per unit furnace wall is as follows:

[0041] Among them, is the heat absorption of the water wall per unit furnace wall; is the blackbody radiation constant; is the average temperature of the fouling layer on the slagging water wall tube.

[0042] Specifically, the calculation formula for the average temperature of the fouling layer on the slagging water wall tube is as follows:

[0043] Among them, is the heat absorption of the water wall.

[0044] Specifically, the calculation formula for the saturated water temperature in the water wall tube is as follows:

[0045] Among them, is the water and steam temperature-pressure function for temperature conversion from the enthalpy value at a certain pressure; is the enthalpy value of the working medium at the inlet of the economizer; is the enthalpy value at the intermediate point of the economizer; is the inlet pressure of the economizer at the rated load.

[0046] Specifically, the formula for the average thickness of the ash deposit layer on the furnace water wall is as follows:

[0047] Among them, is the thermal conductivity of the fouling layer, is the average thickness of the ash deposit layer on the furnace water wall.

[0048] Example 1 A method for quantitatively calculating the thickness of the ash deposit layer based on the excess air coefficient, comprising the following steps: Step one specifically includes: Step 1.1: Based on the relationship between the theoretical combustion temperature and the excess air coefficient, an empirical formula for the theoretical combustion temperature under different excess air coefficients is given based on the heat balance method as:

[0049] In the formula: is the theoretical combustion temperature, K; is the effective heat brought into the furnace per kilogram of fuel, kJ / kg; is the actual flue gas enthalpy at 1800 °C, kJ / kg; is the actual flue gas enthalpy at 2000 °C, kJ / kg; is the actual flue gas enthalpy at 1600 °C, kJ / kg; Among them, the calculation formula for the effective heat brought into the furnace per kilogram of fuel is:

[0050] In the formula: is the heat brought into the furnace by the fuel, kJ / kg; is the ash content on the as-received basis, %; is the excess air coefficient; is the theoretical hot air enthalpy, kJ / kg; is the theoretical cold air enthalpy, kJ / kg; Among them, the formula for calculating the heat brought into the furnace by the fuel is:

[0051] In the formula: is the net calorific value at the as-received basis of coal, kJ / kg; is the moisture content at the as-received basis, %; is the moisture content at the air-dried basis, %; Step 1.2: According to the furnace thermal calculation method, after considering the thermal effective coefficient of the weakening of the flame radiation intensity along the furnace cross-section direction, the formula for calculating the flue gas temperature at the furnace outlet is:

[0052] In the formula: is the flue gas temperature at the furnace outlet, K; M is the parameter considering the influence of the flame center on the furnace heat transfer; is the furnace emissivity; is the average thermal effective coefficient of the water wall; is the furnace wall area, m 3 ; It can be deduced from the formula for calculating the flue gas temperature at the furnace outlet that the formula for calculating the average thermal effective coefficient of the water wall is:

[0053] Step 1.3: The formula for calculating the heat absorption of the water wall is:

[0054] In the formula: is the heat absorption of the water wall, W; is the heat preservation coefficient; is the calculated fuel quantity, kg / s; is the average heat capacity of the combustion products per kilogram of fuel, i.e., the average heat capacity of the flue gas, kJ / (kg·K); Among them, the calculated fuel quantity The calculation formula of

[0055] In the formula: is the superheated steam flow rate, kg / s; is the enthalpy of superheated steam, kJ / kg; is the enthalpy of feed water, kJ / kg; is the reheated steam flow rate, kg / s; is the enthalpy of the reheated steam outlet, kJ / kg; is the enthalpy of the reheated steam inlet, kJ / kg; is the heat loss due to flue gas, %; Among them, the heat loss due to flue gas The calculation formula is:

[0056] In the formula: is the enthalpy of the flue gas discharged, kJ / kg; Among them, the calculation formula for the average heat capacity of the flue gas is:

[0057] In the formula: is the enthalpy of the flue gas at the furnace outlet, kJ / kg; The relationship equation between the average heat effective coefficient of the water wall and the heat absorption of the water wall is specifically:

[0058] In the formula: is the average projected heat flux of the flame, W / m 2 ; Substitute the calculation formula of the average heat effective coefficient of the water wall and the calculation formula of the heat absorption of the water wall into the relationship equation between the average heat effective coefficient of the water wall and the heat absorption of the water wall, and after derivation, the calculation formula of the average projected heat flux of the flame is obtained, specifically:

[0059] In the formula: is the blackbody radiation constant, W / (m 2 ·K 4 ); Step 1.4: The definition formula of the average projected heat flux of the flame is:

[0060] In the formula: is the average temperature of the furnace flame, K; Substitute the calculation formula of the average projected heat flux of the flame into the definition formula of the average projected heat flux of the flame, and the calculation formula of the average temperature of the furnace flame is derived:

[0061] Step 1.5 Due to the radiation heat transfer equation between the furnace flame and the water wall, the calculation formula for the heat absorption of the water wall per unit furnace wall can be obtained:

[0062] In the formula: is the heat absorption of the water wall per unit furnace wall, W / m2 ; is the average temperature of the fouling layer of the slagging water-cooled wall tube, in K; The specific formula for calculating the average temperature of the fouling layer of the slagging water-cooled wall tube derived is as follows:

[0063] Step 1.6 The saturated water temperature in the water-cooled wall tube varies with the excess air coefficient, theoretical combustion temperature, etc., and can be determined by the enthalpy value at the midpoint of the economizer. Therefore, the formula for calculating the enthalpy value at the midpoint of the economizer is:

[0064] In the formula: is the enthalpy value of the working medium at the inlet of the economizer, in kJ / kg; is the enthalpy value at the midpoint of the economizer, in kJ / kg; The specific formula for calculating the saturated water temperature in the water-cooled wall tube is:

[0065] In the formula: is the water and steam temperature-pressure function for temperature conversion from the enthalpy value at pressure; is the inlet pressure of the economizer at rated load; Step two specifically includes: Step 2.1: Take the relative position of the flame center as 0.36, then the influence parameter of the flame center on furnace heat transfer is:

[0066] Step 2.2: Obtain the boiler operation parameters. Refer to Table 1. Combining the influence parameter of the flame center on furnace heat transfer, successively based on the empirical formula of the theoretical combustion temperature, the calculation formula of the flue gas temperature at the furnace outlet, the calculation formula of the average heat effective coefficient of the water-cooled wall, the calculation formula of the average temperature of the furnace flame, the calculation formula of the average temperature of the fouling layer of the slagging water-cooled wall tube, the calculation formula of the heat absorption of the water-cooled wall per unit furnace wall, and the calculation formula of the saturated water temperature in the water-cooled wall tube, calculate the theoretical combustion temperature, the flue gas temperature at the furnace outlet, the average heat effective coefficient of the water-cooled wall, the average temperature of the furnace flame, the average temperature of the fouling layer of the slagging water-cooled wall tube, the heat absorption of the water-cooled wall per unit furnace wall, and the saturated water temperature in the water-cooled wall tube respectively; There is currently a 600 MW boiler for producing superheated steam, and the boiler operation data is collected as shown in Table 1.

[0067] Table 1 Boiler operation data

[0068] Step 2.21: The heat brought into the furnace by the fuel is calculated as:

[0069] Since it can be obtained by checking the enthalpy-temperature table, is the theoretical hot air enthalpy corresponding to the rated load hot air temperature of 330 °C, which is 2698.47 kJ / kg; is the theoretical cold air enthalpy corresponding to the ambient temperature of 20 °C, 169.88 kJ / kg. Then the effective heat brought into the furnace per kilogram of fuel is calculated as:

[0070] Since it can be obtained by checking the enthalpy-temperature table, is the actual flue gas enthalpy at 1800 °C, which is 25898.54 kJ / kg; is the actual flue gas enthalpy at 2000 °C, which is 29087.56 kJ / kg; is the actual flue gas enthalpy at 1600 °C, which is kJ / kg Comparison: (the effective heat brought into the furnace per kilogram of fuel = 26379.92 kJ / kg) > (the actual flue gas enthalpy at 1800 °C = 25898.5 kJ / kg). Based on the empirical formula of the theoretical combustion temperature, the theoretical combustion temperature can be obtained as:

[0071] Step 2.22: Since the influence parameter of the flame center on the heat transfer in the furnace M and the average heat effective coefficient of the water wall can be approximately considered to change only with the ash fouling condition of the furnace, and the furnace emissivity generally changes very little and can be approximately considered unchanged. Taking the furnace emissivity as 0.92, based on the heat balance principle, through thermal calculation, the checked furnace outlet flue gas temperature at the rated load (assuming the furnace outlet flue gas temperature is 1400 °C) is obtained as 1315.49 °C, and the corresponding Kelvin temperature is 1588.49 K;

[0072] By derivation, the specific calculation of the average heat effective coefficient of the water wall is:

[0073] Step 2.23: The calculation of the average temperature of the furnace flame is specifically as follows:

[0074] Step 2.24: The calculation of the average temperature of the fouling layer of the slagging water-cooled wall tubes is specifically as follows:

[0075] Step 2.25: The calculation of the heat absorption of the water-cooled wall per unit furnace wall is specifically as follows:

[0076] Step 2.26: By referring to the enthalpy-temperature table again, it can be obtained that the enthalpy of the flue gas at the rated load and a flue gas temperature of 130 °C is 1513.38 kJ / kg. The calculation of the heat loss due to flue gas is specifically as follows:

[0077] The calculation of the fuel quantity is specifically as follows:

[0078] By referring to the enthalpy-temperature table again, it can be obtained that the enthalpy of the flue gas at the furnace outlet corresponding to the above furnace outlet flue gas temperature of 1315.49 °C is 18274.35 kJ / kg. The calculation of the average heat capacity of the flue gas is specifically as follows:

[0079] The calculation of the enthalpy value at the intermediate point of the economizer is specifically as follows:

[0080] The calculation of the saturation water temperature inside the water-cooled wall tubes is specifically as follows:

[0081] Step three specifically includes: Also, the fouling layer thermal conductivity is According to the formula for the average thickness of the ash deposit layer on the furnace water-cooled wall = Calculation shows that = 5.81 mm.

[0082] This method has high precision and simplicity, can effectively avoid the deviations existing in traditional empirical methods, ensures the accurate assessment of the fouling degree of the boiler water wall, and can not only provide support for boiler operation optimization, but also improve the economy and safety of the boiler. Through the accurate calculation of the average thickness of the fouling layer on the furnace water wall, the real-time monitoring and timely adjustment of the boiler operation state can be realized, thereby improving the operation efficiency of the boiler, reducing the maintenance cost, extending the service life of the equipment, and providing important support for the effective diagnosis and management of the fouling of the boiler water wall.

[0083] Based on the same inventive concept, an embodiment of the present application provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for quantitatively calculating the fouling layer thickness based on the excess air coefficient are implemented. Among them, the memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc.; the processor, network interface, and memory are interconnected through an internal bus, and this internal bus may be an Industry Standard Architecture bus, a Peripheral Component Interconnect standard bus, an Extended Industry Standard Architecture bus, etc., and the bus can be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the program may include program codes, and the program codes include computer operation instructions. The memory may include a memory and a non-volatile memory, and provide instructions and data to the processor.

[0084] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs (Compact Disc Read-Only Memories), optical memories, etc.) containing computer-usable program codes.

[0085] Finally, it should be noted that the above-listed embodiments are only present as one or more specific forms of the technical solutions of the present invention. Their purpose is to clearly elaborate the concept, principle, and application method of the present invention through specific examples, rather than intending to limit the protection scope of the present invention to these specific embodiments. In fact, the real value of the present invention lies in the proposed technical ideas and innovation points, rather than its form of expression or implementation means.

[0086] For those of ordinary skill in the art, after thoroughly reading and understanding the technical solution of the present invention, they are fully capable of making various forms of changes, modifications or equivalent replacements to the specific implementation manners of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the value range of technical parameters, optimizing the algorithm process to improve efficiency, replacing some technical components to achieve better compatibility or reduce costs, etc. As long as the technical solutions after these changes still substantially maintain the technical features required to be protected by the original invention, that is, still can achieve the core functions and effects of the present invention, then these changes should be regarded as falling within the protection scope of the pending claims of the present invention.

[0087] In addition, with the continuous progress and development of technology, new technical means and methods are emerging continuously, which also provides a broad space for the further improvement and perfection of the present invention. Therefore, the protection scope of the present invention should also include those reasonable and foreseeable improvements and expansions based on the existing technology. As long as these improvements and expansions do not deviate from the basic principles and core concepts of the present invention, they should be regarded as equivalents of the present invention and are equally protected by the patent right.

Claims

1. A method for quantitatively calculating the thickness of dust accumulation layer based on excess air coefficient, characterized in that: The following steps are involved: Step 1: Based on the relationship between excess air coefficient and theoretical combustion temperature, establish an empirical formula for theoretical combustion temperature according to the heat balance method; establish a calculation formula for furnace outlet flue gas temperature according to the furnace thermal calculation method, and derive the calculation formula for the average thermal effectiveness coefficient of the water-cooled wall; The calculation formula for the heat absorption of the water-cooled wall and the relationship equation between the average heat effective coefficient of the water-cooled wall and the heat absorption of the water-cooled wall are listed. Combined with the calculation formula for the average heat effective coefficient of the water-cooled wall, the calculation formula for the average projected heat flux of the flame is derived; The definition of flame average projected heat flux is listed, and combined with the calculation formula of flame average projected heat flux, the calculation formula of furnace flame average temperature is derived; Based on the radiation heat transfer equation between the furnace flame and the water-cooled wall, the calculation formula for the water-cooled wall heat absorption per unit furnace wall is established, and the calculation formula for the average temperature of the ash layer of the slagging water-cooled wall tube is derived; based on the change of the saturated water temperature in the water-cooled wall tube with the excess air coefficient and the theoretical combustion temperature, the calculation formula for the saturated water temperature in the water-cooled wall tube is listed; Step 2: Obtain the relative position of the flame center and calculate the parameters affecting the heat transfer of the flame center on the furnace; obtain the boiler operating parameters, and combine the parameters affecting the heat transfer of the flame center on the furnace, and calculate the theoretical combustion temperature, the average thermal effectiveness coefficient of the water-cooled wall, the average temperature of the furnace flame, the average temperature of the ash layer of the slagging water-cooled wall tube, the water-cooled wall heat absorption per unit furnace wall, and the saturated water temperature in the water-cooled wall tube based on the empirical formula of the theoretical combustion temperature, the average thermal effectiveness coefficient of the water-cooled wall, the average temperature of the furnace flame, the average temperature of the ash layer of the slagging water-cooled wall tube, the water-cooled wall heat absorption per unit furnace wall, and the saturated water temperature in the water-cooled wall tube respectively; Step 3: List the formula for the average thickness of the ash layer on the furnace water-cooled wall. Based on the average temperature of the ash layer on the slagging water-cooled wall tubes, the water-cooled wall heat absorption per unit furnace wall and the saturated water temperature in the water-cooled wall tubes, the average thickness of the ash layer on the furnace water-cooled wall is calculated.

2. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 1, characterized in that: The empirical formula for the theoretical combustion temperature is: in, is the theoretical combustion temperature; is the effective heat brought into the furnace per kilogram of fuel; is the actual flue gas enthalpy at 1800°C; is the actual flue gas enthalpy at 2000℃; is the actual flue gas enthalpy at 1600℃.

3. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 2 is characterized in that: The calculation formula of furnace outlet smoke temperature is as follows: in, is the flue gas temperature at the furnace outlet; M It is the parameter that affects the heat transfer of the furnace by the flame center; is the furnace blackness; is the average thermal effectiveness coefficient of the water-cooled wall; is the furnace wall area.

4. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 3 is characterized in that: The calculation formula of the average thermal effectiveness coefficient of the water-cooled wall is as follows: 。 5. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 4 is characterized in that: The calculation formula for the average furnace flame temperature is as follows: in, is the average furnace flame temperature.

6. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 5, characterized in that: The specific calculation formula for the heat absorption of the water-cooled wall per unit furnace wall is: in, The heat absorbed by the water-cooled wall on the unit furnace wall; is the blackbody radiation constant; It is the average temperature of the ash layer of the slagging water-cooled wall tube.

7. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 6, characterized in that: The specific calculation formula for the average temperature of the ash layer of the slagging water-cooled wall tube is: in, The water-cooled wall absorbs heat.

8. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 7, characterized in that: The specific calculation formula for the saturated water temperature in the water-cooled wall tube is: in, for Enthalpy under pressure Water and steam temperature-pressure functions for temperature conversion; is the enthalpy of the working fluid at the economizer inlet; is the enthalpy of the midpoint of the economizer; It is the inlet pressure of economizer at rated load.

9. The method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient according to claim 8, characterized in that: The formula for the average thickness of the ash layer on the furnace water-cooled wall is as follows: in, is the thermal conductivity of the dirt layer, It is the average thickness of the ash layer on the water-cooled wall of the furnace.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method for quantitatively calculating the thickness of the dust layer based on the excess air coefficient as described in any one of claims 1 to 9 are implemented.

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