Bidirectional coupling linkage calculation model for in-furnace combustion and water-cooled wall hydrodynamic characteristics

Abstract

The invention discloses a bidirectional coupling linkage calculation model for in-furnace combustion and water-cooled wall hydrodynamic characteristics, relates to the technical field of hydrodynamic calculation, and is used for accurately realizing in-furnace combustion monitoring and water-cooled wall full-screen tube wall temperature measurement. The calculation model provided by the invention comprises a water power module and a Fluent module; the water power module is used for calculating working medium side information based on the provided thermal load boundary; and the Fluent module is used for converting the working medium side information into a wall surface condition, calculating and outputting thermal load distribution, sending the thermal load distribution to a thermal load boundary formula to calculate a new thermal load boundary, and sending the new thermal load boundary to the water power module to realize coupling interaction of the water power module and the Fluent module. According to the model, the thermal load is continuously corrected, and then hydrodynamic calculation is carried out, so that the accuracy is higher. The method is suitable for hydrodynamic calculation of the boiler.

Description

Technical Field

[0001] The invention relates to the technical field of hydrodynamic calculation, and in particular to hydrodynamic calculation based on a two-way coupled linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics. Background Art

[0002] Under the background of "dual carbon", in order to achieve the "dual carbon" target of pollutant emissions from coal-fired boilers of power generation units, it is inevitable that the safe, environmentally friendly and efficient operation of coal-fired boilers will bring higher difficulties. The relationship between safety, environmental protection and efficiency is mutually influential and mutually opposed. Among them, for power plant operators, the safe operation of boilers is the first problem to be solved. The main problems are concentrated on the leakage of water-cooled walls, superheaters, reheaters, and economizers (referred to as "four pipes"), and the main reasons are overheating, wear, coking, high-temperature corrosion, etc., which lead to deterioration of boiler heat transfer, high exhaust temperature, low boiler efficiency, etc. At present, for operators, the combustion in the boiler furnace is in a "black box" state, and it is impossible to judge the problem location in the full operation of the boiler in real time, and it is difficult to provide accurate solutions.

[0003] Especially when the unit is deeply peak-shaving, due to the long-term deviation of the load conditions from the design conditions, the deviations on the combustion side and the working fluid side will be much greater than the rated conditions. When the boiler is deeply peak-shaving, the boiler steam production is small, the superheater heating surface is poorly cooled, and the screen superheater, rear screen superheater, high-temperature superheater and high-temperature reheater may have local overtemperatures exceeding the oxidation temperature. Long-term local overtemperature may cause aging of the heating surface material, thereby affecting the safe, reliable and stable operation of the unit. At present, in actual operation of the boiler, the water-cooled wall cannot obtain the temperature of the fire side, and the steam temperature measurement points of each tube outlet of the convection heating surface are incomplete. Only some tube measurement points can be alarmed, and full-screen monitoring is impossible. The actual steam temperature cannot replace the actual wall temperature of the heating surface, and the most dangerous wall temperature cannot be directly obtained.

[0004] In summary, when the boiler is running at low load, the uneven distribution of furnace heat load increases, and the increase in the water-cooled wall circuit heat absorption deviation will cause the flow deviation to increase, which is easy to cause water circulation stagnation, backflow and heat transfer deterioration. This will cause boiler overheating, tube bursting and leakage. Due to the complexity of combustion and the high temperature and high pressure characteristics of the furnace, it is currently impossible to use existing measurement technology to accurately realize furnace combustion monitoring and water-cooled wall full-screen tube temperature measurement. Summary of the invention

[0005] The present invention establishes a two-way coupled linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics to accurately realize furnace combustion monitoring and measurement of water-cooled wall full-screen tube wall temperature.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a two-way coupled linkage calculation model for furnace combustion and water-cooled wall hydrodynamic characteristics, including a hydrodynamic module and a Fluent module;

[0008] The hydrodynamic module is used to calculate the working fluid side information based on the provided heat load boundary;

[0009] The Fluent module is used to convert the working fluid side information into wall conditions and calculate the output heat load distribution. It is also used to send the heat load distribution to the heat load boundary formula to calculate a new heat load boundary and send it to the hydrodynamic module to achieve coupling interaction between the hydrodynamic module and the Fluent module.

[0010] Furthermore, in a preferred embodiment, the working fluid side information includes loop pressure, flow rate and temperature distribution.

[0011] Furthermore, in another preferred embodiment, the heat load boundary formula is:

[0012] Q=(hA)(T g -T s )

[0013]

[0014] Where Q is the heat flux, h is the convective heat transfer coefficient, A is the heat transfer area, T g is the temperature of the gas or fluid, T s is the wall temperature.

[0015] Furthermore, in a preferred embodiment, the hydrodynamic module is used to implement working fluid side information calculation by interacting with the IFC97 module.

[0016] Furthermore, there is a preferred embodiment, which also includes a visualization display module for displaying the calculation results of the Fluent module.

[0017] The present invention also provides a hydrodynamic iterative calculation method based on the bidirectional coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics described in the above embodiment, and the calculation method comprises the following steps:

[0018] Step 1: Divide the hydrodynamic circuit into segments of width i and height j. In each hydrodynamic circuit unit, a corresponding number of surface grids are corresponding.

[0019] Step 2: The hydrodynamic module is calculated according to the circuit division. Each circuit unit contains heat load, working fluid temperature, and wall temperature. After being converted into the outer wall temperature, it is assigned to all surface meshes in this unit as wall conditions.

[0020] Step 3: After defining the wall temperature conditions, the Fluent module performs heat exchange calculations to obtain a new heat load for each surface grid. The average value of all grid heat loads of a unit is used as the new heat load value of the circuit unit and returned to the hydrodynamic module for calculation.

[0021] Step 4: Repeat the above steps 2 and 3 until the heat load convergence meets the requirements and obtain the water and fire side output information after iterative convergence.

[0022] The hydrodynamic iterative calculation method described in the present invention can be fully implemented using computer software. Therefore, correspondingly, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is run by a processor, the hydrodynamic iterative calculation method described above is executed.

[0023] The present invention also provides a computer device, which includes a memory and a processor, wherein a computer program is stored in the memory, and when the processor runs the computer program stored in the memory, the processor executes the above-mentioned hydrodynamic iterative calculation method.

[0024] The beneficial effects of the present invention are:

[0025] 1. Conventional hydrodynamic calculations often use the design heat load as an input condition, but the design heat load cannot well reflect the heat exchange state of different units under actual working conditions. For the hydrodynamic calculation of the boiler, the design heat load is not accurate enough and needs to be corrected based on field data. Therefore, the present invention provides a two-way coupling linkage calculation model for furnace combustion and water-cooled wall hydrodynamic characteristics. The model continuously corrects the heat load and then performs hydrodynamic calculations to obtain the loop working fluid temperature distribution and compare it with the actual wall temperature distribution on site. When the loop working fluid temperature distribution calculated by the hydrodynamic calculation is highly consistent with the actual wall temperature distribution on site, the calculation iteration is completed, so that the accuracy is higher and the furnace combustion monitoring and the measurement of the full-screen tube wall temperature of the water-cooled wall can be more effectively realized.

[0026] 2. If a complete route is adopted, for a specific heat load distribution, a single hydrodynamic calculation takes a long time, making it difficult to achieve fast coupling with Fluent. The present invention provides a simplified hydrodynamic iterative calculation method, which fixes the pressure distribution and flow distribution, establishes a UDF coupling model only through temperature calculation, simplifies the model, and saves calculation time.

[0027] The invention is applicable to the hydrodynamic calculation of boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural diagram of a two-way coupled linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics according to the present invention;

[0030] Figure 2 It is a simulation diagram of the hydrodynamic iterative calculation method described in the present invention. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0032] Implementation method 1, see Figure 1 This embodiment is described. This embodiment aims at the technical problem that the existing measurement technology cannot accurately realize the furnace combustion monitoring and the water-cooled wall full screen tube wall temperature measurement, and thus proposes a two-way coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics, and the model includes a hydrodynamic module and a Fluent module;

[0033] The hydrodynamic module is used to calculate the working fluid side information based on the provided heat load boundary;

[0034] The Fluent module is used to convert the working fluid side information into wall conditions and calculate the output heat load distribution. It is also used to send the heat load distribution to the heat load boundary formula to calculate a new heat load boundary and send it to the hydrodynamic module to achieve coupling interaction between the hydrodynamic module and the Fluent module.

[0035] In practical application, this embodiment innovatively proposes a bidirectional coupling linkage calculation model for furnace combustion and water-cooled wall hydrodynamic characteristics. The coupling process of the calculation model is the information interaction and iterative convergence process between the hydrodynamic (Hydro) module and the Fluent module. The hydrodynamic (Hydro) module is responsible for calculating the output working fluid side information (loop pressure, flow, temperature distribution) based on the provided heat load boundary. Among them, the Fluent module is responsible for calculating the output heat load distribution based on the provided working fluid side boundary (converted into wall conditions). The heat load is then sent to the hydrodynamic module for calculation. By continuously correcting the heat load, the calculated hydrodynamic calculation results are more accurate. When the loop working fluid temperature distribution calculated by the hydrodynamics is highly consistent with the actual wall temperature distribution on site, the calculation iteration is completed. The final coupling result is the water and fire side output information after iterative convergence, which can more effectively realize the furnace combustion monitoring and the measurement of the full-screen tube wall temperature of the water-cooled wall.

[0036] Furthermore, the heat load boundary formula in the calculation model is:

[0037] Q=(hA)(T g -T s )

[0038]

[0039] Where Q is the heat flux, h is the convective heat transfer coefficient, A is the heat transfer area, T g is the temperature of the gas or fluid, T s is the wall temperature, and h is the general hydrodynamic scale formula.

[0040] Furthermore, the calculation model also includes an IFC97 module. The hydrodynamic module is used to realize the information calculation on the working fluid side by interacting with the IFC97 module. Specifically, the hydrodynamic module sends the enthalpy / temperature / pressure information of the working fluid to the IFC97 module, and the IFC97 module calculates the enthalpy / temperature / pressure information and sends it to the hydrodynamic module, thereby realizing the interactive calculation between the hydrodynamic module and the IFC97 module.

[0041] Furthermore, the calculation model also includes a visualization module for displaying the calculation results of the Fluent module.

[0042] Furthermore, the calculation model also includes a corresponding calculation program, which is used to recalculate the heat load distribution calculated by the Fluent module, send the calculation results to the heat load boundary formula, calculate the new heat load boundary, and use it for the hydrodynamic (Hydro) module. The calculation program is a discretized equation, which defines boundary conditions, physical models, laws, and heat change rate formulas;

[0043] Among them, boundary conditions include geometric conditions, inlet conditions, outlet conditions and solid boundary conditions;

[0044] Physical models include turbulence, radiation, multiphase flow, gas phase reactions, and surface reactions;

[0045] Certainties include conserved variables and constitutive equations;

[0046] The heat change rate formula is as follows:

[0047]

[0048]

[0049] Where T represents the temperature vector, R represents the reaction rate, ρ,ρu,ρv,ρw,ρe,ρy i Represents different pressure components or physical parameters.

[0050] Embodiment 2: This embodiment provides a hydrodynamic iterative calculation method based on the two-way coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics described in the above embodiment 1, and the method includes the following steps:

[0051] Step 1: Divide the hydrodynamic circuit into segments of width i and height j. In each hydrodynamic circuit unit, a corresponding number of surface grids are corresponding.

[0052] Step 2: The hydrodynamic module is calculated according to the circuit division. Each circuit unit contains heat load, working fluid temperature, and wall temperature. After being converted into the outer wall temperature, it is assigned to all surface meshes in this unit as wall conditions.

[0053] Step 3: After defining the wall temperature conditions, the Fluent module performs heat exchange calculations to obtain a new heat load for each surface grid. The average value of all grid heat loads of a unit is used as the new heat load value of the circuit unit and returned to the hydrodynamic module for calculation.

[0054] Step 4: Repeat steps 2 and 3 above until the heat load convergence meets the requirements and obtain the water and fire side output information after iterative convergence.

[0055] In practical application, this embodiment

[0056] The wall is defined as: Tnode = T[i,j],

[0057] The heat load correction is: q[i,j]=average(qnode);

[0058] The specific calculation method is:

[0059] (1) The hydrodynamic circuit is divided into segments of width i and height j. Each hydrodynamic circuit unit corresponds to a certain number of surface meshes (depending on the actual wall mesh division).

[0060] (2) The hydrodynamics are calculated according to the circuit division. Each circuit unit has parameters such as heat load, working fluid temperature, and wall temperature, which are converted into external wall temperature and assigned to all surface meshes within the unit as wall conditions.

[0061] (3) After the wall temperature conditions are defined, Fluent performs heat exchange calculations to obtain a new heat load for each surface grid. The average heat load of all grids in a unit is used as the new heat load value of the circuit unit and returned to the hydrodynamic calculation.

[0062] (4) Repeat steps 2 and 3 above until the heat load converges to meet the requirements.

[0063] Embodiment 3: This embodiment provides a hydrodynamic iterative calculation system, the system comprising:

[0064] A storage device for dividing the hydrodynamic circuit into i-width segments and j-height segments, and corresponding to a corresponding number of surface grids in each hydrodynamic circuit unit;

[0065] It is used to calculate according to the circuit division using the hydrodynamic module. Each circuit unit contains heat load, working fluid temperature, and wall temperature. After being converted into the outer wall temperature, it is assigned to all surface grids in this unit as a storage device for wall conditions.

[0066] It is used to define the wall temperature conditions. The Fluent module performs heat exchange calculations to obtain the new heat load of each surface grid. The average value of the heat load of all grids of a unit is used as the new heat load value of the circuit unit and returned to the storage device for hydrodynamic calculations.

[0067] A storage device for repeating the above steps until the heat load converges to meet the requirements and obtaining the output information of the water and fire sides after iterative convergence.

[0068] Embodiment 4: This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the hydrodynamic iterative calculation method described in the above embodiment 2 is executed.

[0069] Embodiment 5: This embodiment provides a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the processor runs the computer program stored in the memory, the processor executes the hydrodynamic iterative calculation method described in the above embodiment 2.

[0070] A computer device provided in this embodiment, the hardware device of this part is a general model and is not shown in the form of a diagram. The system includes a processor and a memory, wherein the processor and the memory can be connected via a bus or other means. The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs, non-transient computer executable programs and modules, and corresponding program instructions / modules. The processor executes various functional applications and data processing of the processor by running the non-transient software programs, instructions and modules stored in the memory, so as to realize the hydrodynamic iterative calculation method and steps based on the bidirectional coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics in the above method embodiment.

[0071] Implementation Method 6: See Figure 2 This embodiment is described as follows: This embodiment is a simulation verification of the hydrodynamic iteration calculation method described in the second embodiment;

[0072] like Figure 2 As shown in the figure, it can be seen that in the process of continuous iterative correction, the actual data is approximately equal to the calculated data, which fully proves that the hydrodynamic iterative calculation method described in this embodiment is more accurate.

[0073] In summary, the above-mentioned implementation method provides a bidirectional coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics. The model continuously corrects the heat load and then performs hydrodynamic calculations to obtain the loop working fluid temperature distribution and compares it with the actual wall temperature distribution on site. When the loop working fluid temperature distribution calculated by the hydrodynamics is highly consistent with the actual wall temperature distribution on site, the calculation iteration is completed, thereby achieving higher accuracy and more effective furnace combustion monitoring and water-cooled wall full-screen tube wall temperature measurement.

[0074] Furthermore, the hydrodynamic iterative calculation method implemented by the bidirectional coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics fixes the pressure distribution and flow distribution, and establishes the UDF coupling model only through temperature calculation, which simplifies the model and saves calculation time.

[0075] Furthermore, the technical solution proposed in the above implementation method can accurately predict the heat flux density and steam flow distribution of the boiler water-cooled wall and heating surface, and modify the model and program based on a large amount of field data and test conditions of the units that have been put into operation, and continuously improve the calculation ability. It provides theoretical basis and technical support for subsequent new units and renovation projects, and further enhances the core competitiveness of the product.

[0076] In the above description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0077] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0078] The above description is only the implementation mode of the present invention and is not limited to the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A two-way coupled calculation model for furnace combustion and water-cooled wall hydrodynamic characteristics, characterized in that: Includes hydrodynamic module and Fluent module; The hydrodynamic module is used to calculate the working fluid side information based on the provided heat load boundary; The Fluent module is used to convert the working fluid side information into wall conditions and calculate the output heat load distribution. It is also used to send the heat load distribution to the heat load boundary formula to calculate the new heat load boundary and send it to the hydrodynamic module to realize the coupling interaction between the hydrodynamic module and the Fluent module.

2. A two-way coupled linkage calculation model for furnace combustion and water-cooled wall hydrodynamic characteristics according to claim 1, characterized in that: The working fluid side information includes circuit pressure, flow and temperature distribution.

3. The two-way coupled linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics according to claim 1 is characterized in that: The heat load boundary formula is: Q=(hA)(T g -T s ) Where Q is the heat flux, h is the convective heat transfer coefficient, A is the heat transfer area, T g is the temperature of the gas or fluid, T s is the wall temperature.

4. A two-way coupled calculation model for furnace combustion and water-cooled wall hydrodynamic characteristics according to claim 1, characterized in that: The hydrodynamic module is used to realize the calculation of working fluid information by interacting with the IFC97 module.

5. The two-way coupled linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics according to claim 1 is characterized in that: It also includes a visualization module for displaying the calculation results of the Fluent module.

6. The hydrodynamic iterative calculation method implemented by the bidirectional coupling linkage calculation model of furnace combustion and water-cooled wall hydrodynamic characteristics according to any one of claims 1 to 5, characterized in that: The method is: Step 1: Divide the hydrodynamic circuit into segments of width i and height j. In each hydrodynamic circuit unit, a corresponding number of surface grids are corresponding. Step 2: The hydrodynamic module is calculated according to the circuit division. Each circuit unit contains heat load, working fluid temperature, and wall temperature. After being converted into the outer wall temperature, it is assigned to all surface meshes in this unit as wall conditions. Step 3: After defining the wall temperature conditions, the Fluent module performs heat exchange calculations to obtain a new heat load for each surface grid. The average value of all grid heat loads of a unit is used as the new heat load value of the circuit unit and returned to the hydrodynamic module for calculation. Step 4: Repeat steps 2 and 3 above until the heat load convergence meets the requirements and obtain the water and fire side output information after iterative convergence.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, which, when executed by a processor, executes the hydrodynamic iterative calculation method according to claim 6.

8. A computer device, characterized in that: The device comprises a memory and a processor, wherein a computer program is stored in the memory, and when the processor runs the computer program stored in the memory, the processor executes the hydrodynamic iterative calculation method according to claim 6.

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