A numerical simulation and hydrodynamic collaborative integrated calculation method for a boiler furnace

Abstract

The present invention discloses a method for integrated calculation of boiler furnace numerical simulation and hydrodynamics. Through the integrated calculation method of furnace numerical simulation and hydrodynamics, and through numerical simulation calculation of furnace combustion, the combustion conditions and heat load distribution in the furnace can be accurately obtained. Numerical simulation calculations can provide a reliable calculation basis for hydrodynamic calculations, ensuring the accuracy of data such as hydrodynamic input heat flux density. Hydrodynamic calculations can provide calculation boundary conditions for the numerically simulated furnace wall. The water-cooled wall temperature distribution output by the hydrodynamic calculation results can be used as the wall boundary condition for the numerical simulation calculation, further improving the accuracy of the numerical simulation of furnace combustion. The calculation results can guide further operation adjustments and design modifications of the boiler, and propose practical improvement measures to ensure the safe operation of the boiler during deep peak load regulation and the blending of complex fuels.

Description

Technical Field

[0001] The present invention belongs to the field of boilers for thermal power plants, and in particular relates to a method for integrated calculation of boiler furnace numerical simulation and coordinated hydrodynamics. Background Art

[0002] Under the "dual carbon goals," domestic coal-fired units are frequently participating in peak-shaving operations to increase their capacity to absorb renewable energy. This frequent peak-shaving requires units to respond quickly to loads and possess the ability to rapidly start and stop for peak-shaving. This complicates unit operating conditions, and during periods of deep peak-shaving, boilers deviate from their designed operating conditions. Furthermore, fuel costs drive a complex and diverse range of coal types. Furthermore, to achieve biomass reduction, resource utilization, and harmlessness, more power plants are integrating coal-fired and biomass-based power generation technologies, further complicating combustion and thermal load conditions within power plant boilers.

[0003] The above phenomena cause the boiler to have different degrees of combustion deterioration, coking and slagging, water-cooled wall working fluid flow deviation and other problems, which can easily lead to overheating of the heating surface and even tube burst. Summary of the Invention

[0004] The purpose of the present invention is to provide a collaborative integrated calculation method for numerical simulation and hydrodynamics of boiler furnaces. This method addresses the current problems of water-cooled wall overheating and tube burst in boilers. The combustion conditions in the furnace are obtained through numerical simulation calculations, and the hydrodynamic calculations are performed using the numerically simulated combustion heat load to obtain the flow distribution and metal wall temperature distribution of the water-cooled wall tubes. The method then analyzes and proposes design and operation countermeasures to solve problems such as overheating.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for collaboratively integrating numerical simulation and hydrodynamics of a boiler furnace comprises the following steps:

[0007] Step 1: Basic test of boiler combustion

[0008] Conducted basic combustion tests on coal-fired power plant boilers to obtain boundary conditions for numerical calculations;

[0009] Step 2: Numerical simulation modeling and hydrodynamic calculation modeling

[0010] Based on the basic test of boiler combustion, hydraulic calculation modeling and furnace numerical simulation modeling are carried out;

[0011] Step 3: Numerical simulation of the entire furnace

[0012] Assume that the temperature distribution of the water-cooled wall of the boiler furnace is t 金属壁面温度k , conduct numerical simulation of the entire furnace, and output the heat flux density distribution along the height direction of the furnace wall and the heat flux density distribution of the furnace horizontal cross section;

[0013] Step 4: Boiler hydrodynamic calculation

[0014] Based on the full furnace numerical simulation results and the output heat flux density distribution along the furnace wall height direction and the furnace horizontal cross-section heat flux density distribution, the boiler water wall heat load and heat absorption deviation coefficient along the furnace height direction are formulated to perform hydrodynamic calculations;

[0015] Step 5: Correction of heat absorption deviation coefficient

[0016] Compare the water-wall tube outlet temperature distribution obtained from the actual boiler test with the hydrodynamic calculation results. If the error between the calculated and measured temperature data is greater than 10%, use the measured temperature data to correct the heat absorption deviation coefficient. After obtaining the corrected heat absorption deviation coefficient, recalculate the hydrodynamics. Once the calculated error is less than 10%, proceed to the next step of calculation.

[0017] Step 6: Output numerical calculation results

[0018] After the hydrodynamic calculation is completed, the flow distribution, pressure drop distribution, outlet temperature distribution of each flow circuit, enthalpy distribution and furnace heated metal wall temperature distribution of the heated tube in the furnace are output, which is recorded as t 金属壁面温度k+1 , compare "t 金属壁面温度k+1 ” and “t 金属壁面温度k ", if "t 金属壁面温度k+1 ” and “t 金属壁面温度k If the difference is less than the set value ε, all calculations are completed and the furnace numerical simulation and hydrodynamic calculation results are obtained.

[0019] A further improvement of the present invention is that step six further includes: if "t 金属壁面温度k+1 ” and “t 金属壁面温度k " is greater than the set value ε, then t 金属壁面温度k+1 Assign the value to the wall temperature boundary condition of the numerical calculation, and repeat steps 3, 4, 5, and 6 until "t 金属壁面温度k+1 ” and “t 金属壁面温度k " is less than the set value ε.

[0020] A further improvement of the present invention is that step 1 specifically includes:

[0021] The purpose of the test is to determine the current operating status and characteristics of the boiler, and use this as a relative comparison benchmark for subsequent adjustments and optimization modifications; observe the main performance parameters of the steam-water system, denitrification system, heating surface, blower, primary fan, induced draft fan, air preheater, feed water pump, condensate pump and control system; record the data of the upper and lower furnace wall temperature measurement points of the boiler to ensure that the temperature of each heating surface is within a safe range; the test records the main operating parameters of the boiler, measures the powder tube air velocity and coal powder distribution, measures the oxygen content at the SCR inlet and air preheater outlet, flue gas temperature, CO concentration, NO concentration and atmospheric parameters, and collects raw coal, fly ash and slag samples. The specific test details are carried out in accordance with the relevant test standards for power plant boiler tests.

[0022] A further improvement of the present invention is that, in step 2, the hydrodynamic calculation modeling is performed in accordance with relevant calculation standards.

[0023] A further improvement of the present invention is that, in step 2, the furnace numerical simulation modeling is performed according to the calculation method of commonly used combustion simulation commercial software.

[0024] A further improvement of the present invention is that, in step three, the full furnace numerical simulation is carried out, the meshing is performed to verify the mesh quality and mesh independence, and the calculation model is selected and the boundary conditions are set in combination with the actual test parameters.

[0025] A further improvement of the present invention is that, in step 5, after completing the basic simulation test, the heat absorption deviation coefficient in the furnace width and depth directions is fitted according to the temperature distribution of the water-cooled wall temperature measuring points. The specific fitting method is as follows:

[0026] The enthalpy value of the working fluid at the corresponding position in the water-cooled wall tube represented by each measuring point is calculated based on the temperature value of the wall temperature measuring point. However, the working fluid pressure in the water-cooled wall tube at each measuring point is unknown. Based on the pressure value at the low-load steam-water separator position as a reference, a unified assumption is made about the working fluid pressure at the water-cooled wall measuring point position to obtain the distribution of the working fluid enthalpy value at each measuring point in the water-cooled wall tube. Then, based on the enthalpy value at the water-cooled wall inlet position, the difference in the enthalpy value increase at each measuring point is obtained. The ratio of the enthalpy increase at each measuring point to the average enthalpy increase is used as the heat absorption deviation coefficient.

[0027] Δh i =f(t i ,p)-h entrance

[0028] Where Δh i is the enthalpy increment of the water-cooled wall tube corresponding to the i-th measuring point, t i is the measured temperature of the water-cooled wall tube corresponding to the i-th measuring point, i represents the measuring point number, p is the measured pressure at the water-cooled wall outlet, h 入口 is the enthalpy of the working medium at the water wall inlet, which is determined by the working medium parameters at the economizer outlet;

[0029]

[0030] In the formula is the average value of the enthalpy increment of the water-cooled wall tube, i represents the measurement point number, N is the total number of measurement points, Δh i is the enthalpy increment of the water-cooled wall tube corresponding to the i-th measuring point;

[0031]

[0032] Where η i is the heat absorption deviation coefficient of the water-cooled wall tube at the i-th measuring point, where i represents the measuring point number;

[0033] The endothermic deviation η i It is also related to the thermal load deviation η t , flow deviation of each pipe η q and structural deviation η s related:

[0034] η i =η t η q / η s

[0035] In the preliminary calculation, assuming that the flow deviation and structural deviation of each pipe are the same, the heat absorption deviation is approximately equal to the heat load deviation.

[0036] A further improvement of the present invention is that in steps four and five, the hydrodynamic calculation method is executed in accordance with relevant calculation standards to obtain preliminary calculation results, and the outlet temperature of each water-cooled wall tube is obtained based on the calculation. The error between the actual measured temperature of the low-load water-cooled wall tube and the calculated value is compared. If the error is greater than 10%, the heat load deviation is corrected using the calculated flow deviation and heat absorption deviation, and then the results are substituted and recalculated until the error in the water-cooled wall tube outlet temperature is less than 10%.

[0037] A further improvement of the present invention is that in step six, after the temperature error is less than 10%, the difference between the metal wall temperature distribution used in step three and the calculated metal wall temperature distribution is compared based on the output calculation result. If the difference is greater than the set error, the metal wall temperature distribution output by the hydrodynamic calculation is reassigned to the numerical simulation calculation boundary condition, and the process returns to step three to start iterative calculation until the error is less than the set value, and all numerical simulation calculation results and hydrodynamic calculation results are output.

[0038] The present invention has at least the following beneficial technical effects:

[0039] In response to national policies, existing thermal power units are operating their boilers at off-design conditions during deep peak load regulation and burning complex fuels. This has led to varying degrees of overheating and tube bursts. By integrating furnace numerical simulation with hydrodynamic calculations, we can identify the key factors influencing these issues and propose practical improvement measures to ensure safe operation during deep peak load regulation and the burning of complex fuels.

[0040] Specifically, the present invention has the following advantages:

[0041] (1) Through the combustion test, we can accurately find out the problems existing in the boiler and grasp the basic data of the actual operation of the boiler, providing a reliable basis for numerical calculation.

[0042] (2) Through numerical simulation of furnace combustion, the combustion conditions and heat load distribution in the furnace can be accurately obtained. Since it is difficult to measure the heat load data in the furnace and its accuracy is difficult to guarantee, numerical simulation can provide a reliable basis for hydrodynamic calculations and ensure the accuracy of data such as the hydrodynamic input heat flux density.

[0043] (3) Hydrodynamic calculations can provide computational boundary conditions for the furnace wall surface in numerical simulations. In previous numerical calculations of furnace combustion, the water-cooled wall surface was often assumed to be at a certain temperature. The water-cooled wall temperature distribution output from the hydrodynamic calculation results can be used as the wall boundary condition for numerical simulations, further improving the accuracy of numerical simulations of furnace combustion.

[0044] (4) Through collaborative computing research, we can verify the low-load combustion and hydrodynamic safety characteristics of deep peak-shaving boilers in coal-fired power plants, and propose optimized design solutions and operational countermeasures for the boiler water-cooled wall. For coal-fired power plant boilers with large water-cooled wall temperature deviations, we can verify and calculate the combustion and hydrodynamic characteristics under different operating conditions, and propose optimized design solutions and operational countermeasures for the boiler water-cooled wall. For coal-fired unit biomass coupled power generation projects, we can study and analyze the impact of biomass co-combustion on boiler combustion and hydrodynamics, and propose design and operational countermeasures. Overall, the goal of safe and stable boiler operation can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The figure is a flow chart of a method for collaboratively integrating numerical simulation of boiler furnace and hydrodynamics according to the present invention.

[0046] Figure 2 Schematic diagram of the modeling grid for numerical simulation, where Figure 2 (a) is the furnace model, Figure 2 (b) is the XZ plane grid, Figure 2 (c) is the YZ plane mesh.

[0047] Figure 3 Schematic diagram of the water-cooled wall flow system for hydrodynamic calculations.

[0048] Figure 4 Schematic diagram of furnace temperature distribution.

[0049] Figure 5 is the heat load distribution intention of the furnace, where Figure 5 (a) According to the relative height of the furnace, Figure 5 (b) According to the relative height or depth of the furnace.

[0050] Figure 6 Schematic diagram of calculation error analysis.

[0051] Figure 7 Schematic diagram of metal wall temperature distribution for hydrodynamic calculation. DETAILED DESCRIPTION

[0052] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] like Figure 1 As shown, the present invention provides a method for integrated calculation of boiler furnace numerical simulation and hydrodynamics, which requires a basic test of the combustion of the coal-fired unit boiler before the calculation. During the test phase, the overall operation of the boiler is mainly tested to obtain the boundary conditions of the numerical calculation.

[0054] The purpose of the test is to determine the current operating conditions and characteristics of the boiler and use this as a relative comparison benchmark for subsequent adjustments and optimization modifications. The main performance parameters of the steam-water system, denitrification system, heating surfaces, blower, primary fan, induced draft fan, air preheater, feedwater pump, condensate pump, and control system are observed; data from the upper and lower furnace wall temperature measurement points are recorded to ensure that the temperatures of all heating surfaces are within a safe range. The test records the main operating parameters of the boiler, measures the pulverized coal pipe air velocity and pulverized coal distribution, measures the oxygen content at the SCR inlet and air preheater outlet, flue gas temperature, CO concentration, NO concentration, and atmospheric parameters, and collects samples of raw coal, fly ash, and slag. Specific test details are carried out in accordance with the relevant test standards for power plant boiler testing.

[0055] The present invention provides a boiler furnace numerical simulation and hydrodynamic collaborative integrated calculation method, such as Figure 1 The specific steps include:

[0056] Step 1: Basic test of boiler combustion

[0057] A basic combustion test was carried out on a coal-fired power plant boiler. During the test phase, the overall operation of the boiler was tested, including the pulverizing system test, boiler performance and other test contents. The water-cooled wall outlet temperature data was recorded to understand the main problems of the boiler, and to check whether the operating status of each system was normal, so as to obtain the boundary conditions for numerical calculations.

[0058] Step 2: Numerical simulation modeling and hydrodynamic calculation modeling

[0059] Based on the basic test of boiler combustion, hydrodynamic calculation modeling is carried out, including the determination of the working condition parameters of the water-cooled wall system, the division of the water-cooled wall system calculation loop, the division of the loop pipe section, etc. Simultaneously, the furnace numerical simulation modeling is carried out based on the basic experimental data such as burner structure data, fuel characteristics and test air volume, and the entire furnace is meshed and the calculation boundary conditions are set.

[0060] Step 3: Numerical simulation of the entire furnace

[0061] Assume that the temperature distribution of the water-cooled wall of the boiler furnace (denoted as t 金属壁面温度k ) to perform a full furnace numerical simulation. Perform a combustion numerical simulation according to the test or optimized operating conditions, observe the combustion conditions of the entire furnace, and output the heat flux density distribution along the height direction of the furnace wall and the heat flux density distribution of the furnace horizontal cross section.

[0062] Step 4: Boiler hydrodynamic calculation

[0063] Based on the numerical simulation results of the entire furnace and the output heat flux density distribution along the height direction of the furnace wall and the heat flux density distribution of the horizontal cross-section of the furnace, the heat load and heat absorption deviation coefficient of the boiler water-cooled wall along the height direction of the furnace are proposed, and hydrodynamic calculations are performed.

[0064] Step 5: Correction of heat absorption deviation coefficient

[0065] The outlet temperature distribution of the water-cooled wall tubes obtained from the actual boiler test is compared with the hydrodynamic calculation results. If the error between the calculated and measured temperature data is greater than 10%, the heat absorption deviation coefficient is corrected using the measured temperature data. After obtaining the corrected heat absorption deviation coefficient, the hydrodynamic calculation is repeated until the calculation error is less than 10%, and then the next calculation is carried out.

[0066] Step 6: Output numerical calculation results

[0067] After the hydrodynamic calculation is completed, the flow distribution of the heated tube in the furnace, the pressure drop distribution, the outlet temperature distribution of each flow circuit, the enthalpy distribution and the temperature distribution of the heated metal wall in the furnace (denoted as t 金属壁面温度k+1 ). Compare “t 金属壁面温度k+1 ” and “t 金属壁面温度k", if "t 金属壁面温度k+1 ” and “t 金属壁面温度k " is less than the set value ε, then all calculations are completed and the furnace numerical simulation and hydrodynamic calculation results are obtained. If "t 金属壁面温度k+1 ” and “t 金属壁面温度k " is greater than the set value ε, then t 金属壁面温度k+1 Assign the value to the wall temperature boundary condition of the numerical calculation, and repeat steps 3, 4, 5, and 6 until "t 金属壁面温度k+1 ” and “t 金属壁面温度k " is less than the set value ε.

[0068] A further improvement of the present invention is that step 1 specifically includes:

[0069] The purpose of the test is to determine the current operating conditions and characteristics of the boiler and use this as a relative comparison benchmark for subsequent adjustments and optimization modifications. The main performance parameters of the steam-water system, denitrification system, heating surfaces, blower, primary fan, induced draft fan, air preheater, feedwater pump, condensate pump, and control system are observed; data from the upper and lower furnace wall temperature measurement points are recorded to ensure that the temperatures of all heating surfaces are within a safe range. The test records the main operating parameters of the boiler, measures the pulverized coal pipe air velocity and pulverized coal distribution, measures the oxygen content at the SCR inlet and air preheater outlet, flue gas temperature, CO concentration, NO concentration, and atmospheric parameters, and collects samples of raw coal, fly ash, and slag. Specific test details are carried out in accordance with the relevant test standards for power plant boiler testing.

[0070] A further improvement of the present invention is that, in step 2, the hydrodynamic calculation modeling is performed in accordance with relevant calculation standards. The furnace numerical simulation modeling is performed in accordance with the calculation method of commonly used commercial combustion simulation software.

[0071] A further improvement of the present invention is that in step 3, the full furnace numerical simulation and mesh division are verified for mesh quality and mesh independence. The selection of calculation model and setting of boundary conditions are determined in combination with actual test parameters.

[0072] A further improvement of the present invention is that, in step 4, the hydrodynamic calculation is performed according to relevant calculation standards.

[0073] A further improvement of the present invention is that, in step 5, after completing the basic simulation test, the heat absorption deviation coefficient in the furnace width and depth directions is fitted according to the temperature distribution of the water-cooled wall temperature measuring points. The specific fitting method is as follows:

[0074] The enthalpy value of the working fluid at the corresponding position in the water-cooled wall tube represented by each measuring point is calculated based on the temperature value of the wall temperature measuring point. However, the working fluid pressure in the water-cooled wall tube at each measuring point is unknown. Based on the pressure value at the low-load steam-water separator position as a reference, a unified assumption is made about the working fluid pressure at the water-cooled wall measuring point position to obtain the distribution of the working fluid enthalpy value at each measuring point in the water-cooled wall tube. Then, based on the enthalpy value at the water-cooled wall inlet position, the difference in the enthalpy value increase at each measuring point is obtained. The ratio of the enthalpy increase at each measuring point to the average enthalpy increase is used as the heat absorption deviation coefficient.

[0075] Δh i =f(t i ,p)-h 入口

[0076] Where Δh i is the enthalpy increment of the water-cooled wall tube corresponding to the i-th measuring point, t i is the measured temperature of the water-cooled wall tube corresponding to the i-th measuring point, i represents the measuring point number, p is the measured pressure at the water-cooled wall outlet, h 入口 is the enthalpy of the working medium at the water wall inlet, which is determined by the working medium parameters at the economizer outlet;

[0077]

[0078] In the formula is the average value of the enthalpy increment of the water-cooled wall tube, i represents the measurement point number, N is the total number of measurement points, Δh i is the enthalpy increment of the water-cooled wall tube corresponding to the i-th measuring point;

[0079]

[0080] Where η i is the heat absorption deviation coefficient of the water-cooled wall tube at the i-th measuring point, where i represents the measuring point number;

[0081] The endothermic deviation η i It is also related to the thermal load deviation η t , flow deviation of each pipe η q and structural deviation η s related:

[0082] η i =η t η q / η s

[0083] In the preliminary calculation, assuming that the flow deviation and structural deviation of each pipe are the same, the heat absorption deviation is approximately equal to the heat load deviation.

[0084] A further improvement of the present invention is that in step five, the hydrodynamic calculation results are obtained, the outlet temperature of each water-cooled wall tube is obtained based on the calculation, and the error between the actual measured temperature of the low-load water-cooled wall tube and the calculated value is compared. If the error is greater than 10%, the heat load deviation is corrected using the calculated flow deviation correction and heat absorption deviation, and then the calculation is re-done until the error in the water-cooled wall tube outlet temperature is less than 10%.

[0085] A further improvement of the present invention is that in step 6, after the temperature error is less than 10%, the difference between the metal wall temperature distribution used in step 3 and the calculated metal wall temperature distribution is compared based on the output calculation results. If the difference is greater than the set error, the metal wall temperature distribution output from the hydrodynamic calculation is reassigned to the numerical simulation boundary conditions, and the iterative calculation is restarted in step 3. All numerical simulation results and hydrodynamic calculation results are output until the error is less than the set value.

[0086] Example

[0087] Specific embodiments of the present invention are as follows:

[0088] Step 1: Basic test of boiler combustion

[0089] The test is conducted in accordance with the "Boiler Performance Test Procedure" (ASME PTC 4-1998) or the "Power Plant Boiler Performance Test Procedure" (GB / T 10184-2015), and refers to the "Pulverized Coal Boiler Combustion Adjustment Test Method"; the pulverizing system test is conducted in accordance with the "Power Plant Coal Mill and Pulverizing System Performance Test Procedure" (DL / T467-2004).

[0090] A preliminary operating test was conducted on a subcritical natural circulation boiler. This test, conducted under the power plant's customary operating conditions, aimed to understand the boiler's current operating conditions. The test recorded key boiler operating parameters, measured oxygen content at the SCR inlet and air preheater outlet, flue gas temperature, CO concentration, NO concentration, and other atmospheric parameters. Raw coal, fly ash, and slag samples were collected to determine basic fuel data and calculate boiler thermal efficiency and NOx generation concentration.

[0091] In addition, to understand the fundamentals of the combustion and pulverizing system, the cold primary air volume at the pulverizer inlet was calibrated. This test was conducted without coal being fed into the pulverizer. During the test, the hot air damper was closed, the cold air damper was opened, and the pulverizer air volume was adjusted. The primary air velocity of each pulverized coal pipe at the outlet of each pulverizer was measured, and the actual ventilation volume at the pulverizer inlet was calculated. During these tests, based on the measured primary air velocity deviation, the velocity deviation of each pulverized coal pipe was adjusted to within ±5% using the adjustable reduction holes installed on each pulverized coal pipe. The hot primary air volume and air-to-powder deviation of the pulverizer were measured. The primary air velocity in the hot state with pulverized coal was measured using a standard backrest pipe, and the mill inlet ventilation volume was calculated. The accuracy of the dial air volume indication during hot operation of the pulverizer was verified, and final revisions were made based on the cold test results. Pulverized coal samples from each pulverized coal pipe under each test condition were weighed to determine the pulverized coal distribution within each pulverized coal pipe and to calculate the hot primary air velocity deviation.

[0092] The basic data of the 330MW load test are as follows:

[0093]

[0094]

[0095]

[0096]

[0097] Step 2: Numerical simulation modeling and hydrodynamic calculation modeling

[0098] The numerical simulation uses 3D modeling software to perform full-scale geometric modeling of the prototype furnace, and then meshes the calculation domain using commercial numerical simulation software. In the area where the burner nozzle and the furnace meet, the mesh is encrypted to avoid pseudo-diffusion caused by drastic changes in the flow field. The mesh is gradually sparser in the upper part of the combustion area to reduce the number of meshes and improve the calculation speed. The number of meshes is 1.89 million. The mesh independence verification can meet the calculation accuracy requirements. The furnace modeling and meshing are as follows: Figure 2 shown.

[0099] In the numerical calculation boundary condition setting, the furnace wall was considered to be free of turbulent motion and subject to no-slip boundary conditions. The burner and overburn air inlets were set as mass flow inlet boundaries with a turbulence intensity of 10%. The hydraulic diameter of each inlet was determined based on the specific calculation results of the nozzle size. The wind speeds of each secondary air were specified, and the slip coefficient of the pulverized coal particles was set to 0.8. The furnace outlet was set as a pressure outlet boundary condition, with the outlet pressure set according to the actual boiler operating parameters, taking into account the influence of gravity on the pulverized coal particles.

[0100] The wind boundary conditions of the pulverized coal burner are as follows:

[0101]

[0102]

[0103] The hydrodynamic calculation modeling is carried out based on the heat flux density and heat load unevenness coefficient distribution obtained by numerical simulation. Figure 3 , the method of equating the natural circulation boiler water-cooled wall to a flow network system is adopted, and the water-cooled wall is divided into three types of components: flow circuit, pressure node, and connecting pipe, as shown in the figure. According to the mass conservation equation, momentum conservation equation, and energy conservation equation, a natural circulation boiler water-cooled wall flow distribution calculation model is established. According to the furnace heat load flow coefficient distribution model and the uniform cross-section straight rib heat conduction control equation, a calculation model for the distribution of inner wall temperature, midpoint wall temperature, outer wall temperature, fin root temperature, and fin end temperature along the furnace height direction is established. For specific calculations, refer to the hydrodynamic calculation steps in accordance with the "JB / Z 201-83 Power Plant Boiler Hydrodynamic Calculation Method" and the patent "A General Hydrodynamic Calculation Method for Ultra-Supercritical Boilers" (CN106897547B, 2019-04-12).

[0104] Step 3: Numerical simulation of the entire furnace

[0105] According to the input numerical simulation boundary conditions and calculation model, the whole furnace is numerically simulated using commercial software, and the calculation results such as the whole furnace temperature distribution are obtained as shown in the figure. The heat flux density distribution of the water-cooled wall surface and the heat load unevenness coefficient distribution are derived.

[0106] Step 4: Boiler hydrodynamic calculation

[0107] According to the working condition data of boiler water wall in the test stage, the numerical simulation results mentioned above are used to formulate Figure 5 The heat load and nonuniformity coefficient distribution shown in the figure serve as the basis for the hydrodynamic calculation. The hydrodynamic calculation steps follow the "JB / Z 201-83 Hydrodynamic Calculation Method for Power Plant Boilers" and the patent "A General Hydrodynamic Calculation Method for Ultra-Supercritical Boilers" (CN106897547B, April 12, 2019).

[0108] Step 5: Correction of heat absorption deviation coefficient

[0109] During the preliminary calculation test phase, compare the circuit outlet temperature obtained by hydrodynamic calculation with the measured temperature to see if the error is less than 10%. Figure 6 Error analysis shown.

[0110] Step 6: Output numerical calculation results

[0111] The hydrodynamic results calculated according to step 5 are as follows: Figure 7For the hydrodynamic calculation of the wall temperature distribution, determine whether the water-cooled wall temperature and the wall temperature boundary conditions of the numerical simulation are within the error range. If so, output all calculation results to guide further operation adjustments and design modifications of the boiler. If not, repeat step three with the hydrodynamic calculation of the water-cooled wall temperature distribution as the boundary condition.

[0112] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for integrated calculation of boiler furnace numerical simulation and hydrodynamics, characterized in that: The following steps are involved: Step 1: Basic test of boiler combustion Conducted basic combustion tests on coal-fired power plant boilers to obtain boundary conditions for numerical calculations; Step 2: Numerical simulation modeling and hydrodynamic calculation modeling Based on the basic test of boiler combustion, hydraulic calculation modeling and furnace numerical simulation modeling are carried out; Step 3: Numerical simulation of the entire furnace Assume that the temperature distribution of the water-cooled wall of the boiler furnace is t 金属壁面温度k , conduct numerical simulation of the entire furnace, and output the heat flux density distribution along the height direction of the furnace wall and the heat flux density distribution of the furnace horizontal cross section; Step 4: Boiler hydrodynamic calculation Based on the full furnace numerical simulation results and the output heat flux density distribution along the furnace wall height direction and the furnace horizontal cross-section heat flux density distribution, the boiler water wall heat load and heat absorption deviation coefficient along the furnace height direction are formulated to perform hydrodynamic calculations; Step 5: Correction of heat absorption deviation coefficient The water-cooled wall tube outlet temperature distribution obtained from the actual boiler test is compared with the hydrodynamic calculation results. If the error between the calculated and measured temperature data is greater than 10%, the heat absorption deviation coefficient is corrected using the measured temperature data. After obtaining the corrected heat absorption deviation coefficient, the hydrodynamic calculation is repeated until the calculation error is less than 10%. After completing the basic simulation test, the heat absorption deviation coefficient in the furnace width and depth directions is fitted based on the temperature distribution of the water-cooled wall temperature measurement points. The specific fitting method is as follows: The enthalpy value of the working fluid at the corresponding position in the water-cooled wall tube represented by each measuring point is calculated based on the temperature value of the wall temperature measuring point. However, the working fluid pressure in the water-cooled wall tube at each measuring point is unknown. Based on the pressure value at the low-load steam-water separator position as a reference, a unified assumption is made about the working fluid pressure at the water-cooled wall measuring point position to obtain the distribution of the working fluid enthalpy value at each measuring point in the water-cooled wall tube. Then, based on the enthalpy value at the water-cooled wall inlet position, the difference in the enthalpy value increase at each measuring point is obtained. The ratio of the enthalpy increase at each measuring point to the average enthalpy increase is used as the heat absorption deviation coefficient. Δh i =f(t i ,p)-h 入口 Where Δh i is the enthalpy increment of the water-cooled wall tube corresponding to the i-th measuring point, t i is the measured temperature of the water-cooled wall tube corresponding to the i-th measuring point, i represents the measuring point number, p is the measured pressure at the water-cooled wall outlet, h 入口 is the enthalpy of the working medium at the water wall inlet, which is determined by the working medium parameters at the economizer outlet; In the formula is the average value of the enthalpy increment of the water-cooled wall tube, i represents the measurement point number, N is the total number of measurement points, Δh i is the enthalpy increment of the water-cooled wall tube corresponding to the i-th measuring point; Where η i is the heat absorption deviation coefficient of the water-cooled wall tube at the i-th measuring point, where i represents the measuring point number; The endothermic deviation η i It is also related to the thermal load deviation η t , flow deviation of each pipe η q and structural deviation η s related: or i =the t or q / or s In the preliminary calculation, assuming that the flow deviation and structural deviation of each pipe are the same, the heat absorption deviation is approximately equal to the heat load deviation; Step 6: Output numerical calculation results After the hydrodynamic calculation is completed, the flow distribution, pressure drop distribution, outlet temperature distribution of each flow circuit, enthalpy distribution and furnace heated metal wall temperature distribution of the heated tube in the furnace are output, which is recorded as t 金属壁面温度k+1 , compare "t 金属壁面温度k+1 ” and "t 金属壁面温度k ", if "t 金属壁面温度k+1 ” and "t 金属壁面温度k If the difference is less than the set value ε, all calculations are completed and the furnace numerical simulation and hydrodynamic calculation results are obtained.

2. A boiler furnace numerical simulation and hydrodynamic collaborative integrated calculation method according to claim 1, characterized in that: Step 6 also includes: If "t 金属壁面温度k+1 ” and "t 金属壁面温度k " is greater than the set value ε, then t 金属壁面温度k+1 Assign the value to the wall temperature boundary condition of the numerical calculation, and repeat steps 3, 4, 5, and 6 until "t 金属壁面温度k+1 ” and "t 金属壁面温度k " is less than the set value ε.

3. A boiler furnace numerical simulation and hydrodynamic collaborative integrated calculation method according to claim 1 or 2, characterized in that: Step 1 specifically includes: The purpose of the test is to determine the current operating status and characteristics of the boiler, and use this as a relative comparison benchmark for subsequent adjustments and optimization modifications; observe the main performance parameters of the steam-water system, denitrification system, heating surface, blower, primary fan, induced draft fan, air preheater, feed water pump, condensate pump and control system; record the data of the upper and lower furnace wall temperature measurement points of the boiler to ensure that the temperature of each heating surface is within a safe range; the test records the main operating parameters of the boiler, measures the powder tube air velocity and coal powder distribution, measures the oxygen content at the SCR inlet and air preheater outlet, flue gas temperature, CO concentration, NO concentration and atmospheric parameters, and collects raw coal, fly ash and slag samples.

4. A boiler furnace numerical simulation and hydrodynamic collaborative integrated calculation method according to claim 1 or 2, characterized in that: In step three, the whole furnace is numerically simulated, mesh quality and mesh independence are verified by mesh division, and the calculation model is selected and the boundary conditions are set in combination with the actual test parameters.

5. The method for collaborative integrated calculation of boiler furnace numerical simulation and hydrodynamics according to claim 1 is characterized in that: In steps 4 and 5, based on the outlet temperature of each water-cooled wall tube, compare the error between the measured temperature of the low-load water-cooled wall tube and the calculated value. If the error is greater than 10%, use the calculated flow deviation correction and heat absorption deviation to correct the heat load deviation, and then substitute them into the calculation again until the error of the water-cooled wall tube outlet temperature is less than 10%.

6. The method for integrated calculation of boiler furnace numerical simulation and hydrodynamics according to claim 5 is characterized in that: In step 6, after the temperature error is less than 10%, the difference between the metal wall temperature distribution used in step 3 and the calculated metal wall temperature distribution is compared based on the output calculation results. If it is greater than the set error, the metal wall temperature distribution output by the hydrodynamic calculation is reassigned to the numerical simulation calculation boundary condition, and the process returns to step 3 to start iterative calculation until the error is less than the set value, and all numerical simulation calculation results and hydrodynamic calculation results are output.

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