Method for measuring flow parameters in cement predecomposition furnace and readable storage medium

Abstract

The invention provides a method for measuring flow parameters in a cement pre-decomposition furnace and a readable storage medium, and the method comprises the steps: calculating a conservation equation in each spatial infinitesimal through a two-fluid model according to the structure size, physical properties and operation conditions of the cement pre-decomposition furnace, and obtaining the speed, concentration and temperature distribution; calculating a solution set meeting a steady-state equivalent agglomerate diameter equation of the cement raw material according to the operation conditions, and searching an optimal solution meeting size limiting conditions of agglomerates in the bed; the drag coefficient between particles and fluid is calculated through the optimal solution, the uniform drag coefficient of the double-fluid model is replaced for iterative calculation, and spatial distribution and time evolution of the concentration, the speed and the temperature of a flow field in any infinitesimal element of the reactor are obtained. According to the method, the drag coefficient considering the raw material particle aggregation structure can be obtained, and particle dispersion and temperature distribution in the pre-decomposition furnace can be accurately calculated.

Description

Technical Field

[0001] The invention relates to the technical field of dry process cement production, and in particular to a method for measuring flow parameters in a cement pre-decomposition furnace and a readable storage medium. Background Art

[0002] The cement precalciner is a high-temperature treatment device in the firing section of the modern dry cement production process. The cement raw material undergoes calcination reaction in the calciner, and the calcined cement raw material enters the rotary kiln for sintering reaction to obtain cement clinker. The cement raw material particles are finely ground into powder in the previous stage, and the fineness is usually controlled during production so that 10-30% of the particles can be retained on a 90-micron sieve. The van der Waals force between very fine particles and the drag interaction between particles and fluids will cause the cement raw material to form agglomerate structures in the precalciner. These agglomerate structures have a significant impact on the particle dispersion, heat transfer efficiency and calcination rate in the precalciner. The traditional gas-solid interaction drag coefficient that does not consider the agglomerate structure is usually 2 orders of magnitude higher than the actual drag coefficient. Therefore, accurate prediction of particle dispersion and temperature distribution in the precalciner is crucial to the design, operation, control and amplification of the precalciner. The drag prediction method between gas and raw material particles in the precalciner is one of the core contents to achieve this work goal.

[0003] The traditional drag coefficient between gas and raw meal in the precalciner usually adopts a uniform drag coefficient based on the experimental experience of dispersed fluidization, combined with a detailed raw meal particle size distribution. This calculation method is adopted by most researchers and practitioners. This method does not take into account the van der Waals force between raw meal particles and the agglomeration structure caused by the van der Waals force, so the accuracy of predicting particle dispersion and temperature distribution in the precalciner is limited. In the precalciner, the calculated value without considering the influence of the agglomeration structure is very different from the actual value, and the results are in different orders of magnitude. The direct consequence is the distortion of the flow field particle concentration and the temperature distribution in the reactor during the design or simulation calculation.

[0004] Therefore, it is urgent to develop a new measurement method for raw material dispersion and temperature distribution in the precalciner to improve the calculation speed and accuracy of the existing measurement method. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for measuring flow parameters in a cement predecomposition furnace and a readable storage medium, which combines a drag correction model considering the agglomerate structure with a two-fluid model, and constructs a steady-state equivalent agglomerate diameter equation under the actual operating conditions of the decomposition furnace based on the force balance model of the agglomerates, thereby avoiding the need to analyze the effects of a large number of van der Waals forces between particles in the predecomposition furnace and avoiding the need to track the dynamic changes of raw material agglomerates. Not only is the calculation process simpler, but it also has the advantage of high calculation accuracy, and can accurately predict the dispersion of raw materials in the cement predecomposition furnace, and grasp the internal laws of the predecomposition furnace, thereby fundamentally ensuring the design, operation, control and amplification.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for measuring flow parameters in a cement precalcining furnace, the measuring method comprising:

[0008] (1) Initialize the flow field and boundary conditions according to the physical parameters of the fluid and operating conditions;

[0009] (2) The two-fluid model is used to calculate the mass conservation equation, momentum conservation equation and energy conservation equation in each spatial element to obtain the velocity distribution, concentration distribution and temperature distribution in the spatial element; the velocity distribution includes the true velocity u of the gas in the spatial element. g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g ;

[0010] (3) According to the inner diameter d of the cement precalciner t and the true velocity u of the gas in the space element g , the solution set satisfying the steady-state equivalent agglomerate diameter equation is calculated;

[0011] (4) in the solution set obtained in step (3), finding the optimal solution that satisfies the aggregate size restriction condition in the cement precalciner;

[0012] (5) Based on the optimal solution obtained in step (4) and the true velocity u of the gas in the spatial element obtained in step (2), g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g , calculate the drag coefficient;

[0013] (6) Substituting the drag coefficient obtained in step (5) for the original drag coefficient in the mass conservation equation, momentum conservation equation and energy conservation equation in step (2), and looping steps (2) to (5) to perform iterative calculation until the iteration termination condition is reached, thereby obtaining a corrected drag coefficient.

[0014] The material system in the cement pre-decomposition furnace is relatively complex. On the one hand, the viscosity of cement itself is relatively large, and its particles will continuously agglomerate, which makes it difficult to calculate its drag coefficient. The measurement method of raw material dispersion and temperature distribution in the cement pre-decomposition furnace provided by the present invention combines the agglomeration structure drag model with the two-fluid model, and constructs a drag correction model based on the steady-state equivalent agglomerate diameter equation on the basis of the existing technology. It no longer directly analyzes the van der Waals force between particles and tracks the dynamic changes of raw material agglomerates. Not only is the calculation process simpler, but it also improves the accuracy of the calculation of the traditional pre-decomposition furnace, which is more conducive to the design and scale-up of the pre-decomposition furnace.

[0015] The steady-state equivalent agglomerate diameter equation in the present invention means that when the aggregation rate and the crushing rate of the agglomerates reach equilibrium, the particle size distribution of the agglomerates in the precalciner can be equivalent to the equivalent agglomerate particle size. The equivalent agglomerate particle size can be calculated by physical quantities at the precalciner level and the particle level. The physical quantities are constrained by the force balance equation, and the optimal solution is obtained by the agglomerate particle size restriction condition in the precalciner.

[0016] Preferably, the calculation in step (2) is performed using a two-fluid model calculation code or commercial computational fluid dynamics software.

[0017] Preferably, the commercial computational fluid dynamics software includes any one of ANSYS CFX, ANSYS Fluent, Phoenics, STAR-CD, Barracuda, OpenFOAM or MFIX, or a combination of at least two thereof.

[0018] Preferably, the temperature distribution in step (2) includes the actual temperature T of the fluid in the space element. g and the real temperature T of the particles in the space element p .

[0019] Preferably, the establishment of the steady-state equivalent agglomerate diameter equation in step (3) includes: when the aggregation rate and the crushing rate of the agglomerates reach equilibrium, the particle size distribution of the agglomerates in the cement precalciner is equivalent to the equivalent agglomerate particle size, and the force balance equation is used as a constraint condition.

[0020] Preferably, the constraint condition in the steady-state equivalent agglomerate diameter equation in step (3) is as shown in formula (1):

[0021] F g +F v =F d，a +F c Formula (1).

[0022] In formula (1), F grepresents the gravity of the aggregate, F v represents the van der Waals force between aggregates, F d,a The drag force on the aggregates, F c Represents the collision force between agglomerates.

[0023] Preferably, the gravity F exerted on the agglomerates in step (3) is g The calculation formula is Where ρ a represents the density of the aggregate, d a is the steady-state equivalent aggregate diameter. g,a is the porosity of aggregates, ρ g is the true density of the gas, and g is the gravitational acceleration.

[0024] The density of the agglomerates ρ a =(1-ε g,a )ρ p , where ρ p is the actual density of the particle.

[0025] Preferably, the van der Waals force F between the aggregates in step (3) v The calculation formula is shown in formula (2):

[0026]

[0027] In formula (2), H is the Hamaker coefficient, δ is the separation distance between two agglomerates, is the ratio of the average diameters of the two aggregates.

[0028] Preferably, under steady-state conditions, define

[0029] Preferably, the drag force F on the agglomerate is d,a The calculation formula is shown in formula (3):

[0030]

[0031] The ρ in formula (3) g represents the gas density, u slip,a is the apparent slip velocity of the agglomerates, d a represents the steady-state equivalent aggregate diameter, ε g,a Indicates the porosity of the aggregate, C D1 represents the drag coefficient of a single particle.

[0032] C D1 The definition of is: Among them, Re a Reynolds number, Re a The definition of ug is the gas viscosity.

[0033] Preferably, the collision force F between the agglomerates in step (3) is c The calculation formula is shown in formula (4):

[0034]

[0035] In formula (4), V is the relative collision velocity of the two agglomerates, ρ a is the density of the agglomerate, κ is a function of the particle Poisson's ratio and Young's modulus, and its calculation formula is Where v is Poisson's ratio and E is Young's modulus.

[0036] Preferably, the particle size of the cement material in the cement pre-decomposition furnace is in the range of 0.3 to 500 μm. Preferably, the size restriction condition of the agglomerates in the cement pre-decomposition furnace in step (4) is: the size of the agglomerates is larger than the particle size d of the cement particles. p And smaller than the inner diameter d of the cement precalciner t That is, d a ∈(d p , d t ).

[0037] Preferably, the calculation model of the drag coefficient in step (5) is as shown in formula (5):

[0038]

[0039] In formula (5), C D 2 represents the drag coefficient of the particle group, ρ g Indicates gas density; ε s represents the solid content, d a represents the steady-state equivalent agglomerate diameter, g represents the gravitational acceleration; is the gas velocity, represents the particle velocity and β represents the unit volume drag coefficient of the agglomerate.

[0040] Among them C D2 Satisfying formula (7):

[0041]

[0042] Preferably, the condition for terminating the iteration in step (6) is that the velocity distribution, concentration distribution and temperature distribution satisfy the convergence conditions of the mass conservation equation, momentum conservation equation and energy conservation equation.

[0043] Preferably, the total duration of the calculation is 0.1 to 500 seconds, for example, 5 to 20 seconds.

[0044] In the present invention, the same symbols represent the same physical quantities and have the same physical meanings.

[0045] In a second aspect, the present invention provides a readable storage medium storing a program written according to the method for measuring flow parameters in a cement pre-decomposition furnace described in the first aspect.

[0046] The computer-readable storage medium provided by the present invention stores a program written according to the method for measuring flow parameters in a cement pre-decomposition furnace described in the first aspect, and the computer storage medium can be connected to existing commercial computational fluid dynamics software to achieve the prediction of the flow parameter distribution in the cement pre-decomposition furnace.

[0047] Compared with the prior art, the present invention has at least the following beneficial effects:

[0048] (1) The method for measuring flow parameters in a cement precalciner provided by the present invention takes into account the influence of the agglomeration structure of cement raw materials in the cement precalciner on the drag coefficient, thereby correcting the situation in which the drag coefficient is too high in conventional methods;

[0049] (2) Compared with the method of directly analyzing the van der Waals force between particles and tracking the dynamic changes of raw material agglomerates, the method for measuring flow parameters in the cement precalciner provided by the present invention has a simpler calculation process and saves time. In addition, the present invention can also obtain accurate calculation results under coarse grids. Typically, the number of grids in Example 1 only needs to be 250 to 2700 times the average particle size of the particles, which is more suitable for considering the influence of van der Waals force between particles in the calculation of industrial cement calciners;

[0050] (3) The method for measuring flow parameters in a cement pre-decomposition furnace provided by the present invention can reasonably calculate the dispersion process of raw materials in the cement pre-decomposition furnace, accurately realize the flow calculation of the pre-decomposition furnace, and reasonably predict the particle concentration and temperature distribution of the pre-decomposition furnace, thereby guiding related process control, optimization design and even process amplification. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A flow chart of a method for measuring raw material dispersion and temperature distribution in a cement precalcining furnace provided in a specific embodiment of the present invention;

[0052] Figure 2 It is a schematic diagram of the agglomerate force balance of the steady-state equivalent agglomerate diameter equation used in a specific embodiment of the present invention;

[0053] Figure 3 This is a practical application diagram of Example 1 of the present invention in the calculation of raw material dispersion and temperature distribution in a cement precalcining furnace;

[0054] Figure 4The figure is a comparison between the gas temperature prediction result in Example 1 and the calculation result in Comparative Example 1. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0056] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0057] As a specific embodiment of the present invention, a method for measuring flow parameters in a cement precalcining furnace is provided, such as Figure 1 As shown, the measuring method comprises:

[0058] (1) Initialize the flow field and boundary conditions according to the physical parameters of the fluid and operating conditions;

[0059] (2) The two-fluid model is used to calculate the mass conservation equation, momentum conservation equation and energy conservation equation in each spatial element to obtain the velocity distribution, concentration distribution and temperature distribution in the spatial element; the velocity distribution includes the true velocity u of the gas in the spatial element. g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g ;

[0060] (3) According to the inner diameter d of the cement precalciner t and the true velocity u of the gas in the space element g , the solution set satisfying the steady-state equivalent agglomerate diameter equation is calculated;

[0061] (4) in the solution set obtained in step (3), finding the optimal solution that satisfies the aggregate size restriction condition in the cement precalciner;

[0062] (5) Based on the optimal solution obtained in step (4) and the true velocity u of the gas in the spatial element obtained in step (2), g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g , calculate the drag coefficient;

[0063] (6) Substituting the drag coefficient obtained in step (5) for the original drag coefficient in the mass conservation equation, momentum conservation equation and energy conservation equation in step (2), and looping steps (2) to (5) to perform iterative calculation until the iteration termination condition is reached, thereby obtaining a corrected drag coefficient.

[0064] The steady-state equivalent agglomerate diameter equation used in this specific embodiment is constructed based on the force balance model of agglomerates. The force balance diagram acting on agglomerates is shown in FIG. Figure 2 shown.

[0065] Example 1

[0066] This embodiment 1 provides a method for measuring flow parameters in a cement precalcining furnace, the measuring method comprising the following steps:

[0067] (1) Initializing the flow field and boundary conditions according to the physical properties and operating conditions of the fluid; the initialization flow field and boundary conditions are to be determined according to the actual physical properties and operating conditions, and the structural dimensions, particle size, particle density, fluid density, fluid viscosity, apparent fluid velocity and particle flow flux of the cement precalciner are given;

[0068] (2) Using a two-fluid model calculation code or commercial computational fluid dynamics software, the two-fluid model is used to calculate the mass conservation equation, momentum conservation equation, and energy conservation equation in each spatial element to obtain the velocity distribution, concentration distribution, and temperature distribution in the spatial element; the velocity distribution and concentration distribution include the true velocity u of the gas in the spatial element. g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g ; The temperature distribution includes the real temperature T of the fluid in the space element g and the real temperature T of the particles in the space element p ;

[0069] (3) According to the inner diameter d of the cement precalciner t 、The true velocity u of the gas in the space element g , gas and particle physical parameters, and calculate the solution set that satisfies the steady-state equivalent agglomerate diameter equation;

[0070] Specifically, the establishment of the steady-state equivalent agglomerate diameter equation includes: when the aggregation rate and the crushing rate of the agglomerates reach equilibrium, the particle size distribution of the agglomerates in the cement precalciner is equivalent to the equivalent agglomerate particle size, and the force balance equation is used as a constraint condition.

[0071] The constraint condition in the steady-state equivalent agglomerate diameter equation is shown in formula (1):

[0072] F g +F v =F d，a +F c Formula (1)

[0073] In formula (1), F g represents the gravity of the aggregate, F vrepresents the van der Waals force between aggregates, F d,a The drag force on the aggregates, F c Represents the collision force between agglomerates.

[0074] The gravity F of the agglomerates in step (3) g The calculation formula is Where ρ a Indicates the density of the aggregate (kg / m 3 ),d a is the steady-state equivalent agglomerate diameter (m). ε g,a is the porosity of aggregates, ρ g is the true density of the gas (kg / m 3 ), g is the acceleration due to gravity (kg / m 2 ). The density of the agglomerates ρ a =(1-ε g,a )ρ p , where ρ p is the actual density of the particle (kg / m 3 ).

[0075] The van der Waals force F between the aggregates in step (3) v The calculation formula is shown in formula (2):

[0076]

[0077] In formula (2), H is the Hamaker coefficient, δ is the separation distance between two agglomerates, is the ratio of the average diameters of the two aggregates. Under steady-state conditions, define

[0078] The drag force F on the agglomerate d,a The calculation formula is shown in formula (3):

[0079]

[0080] The ρ in formula (3) g Indicates gas density (kg / m 3 ),u slip,a is the apparent slip velocity of the agglomerates (m / s), d a represents the steady-state equivalent aggregate diameter (m), ε g,a Indicates the porosity of the aggregate, C D1 represents the drag coefficient of a single particle.

[0081] C D1 The definition of is: Among them, Re a Reynolds number, Re a The definition of u g is the gas viscosity (Pa·s).

[0082] Preferably, the collision force F between the agglomerates in step (3) is c The calculation formula is shown in formula (4):

[0083]

[0084] In formula (4), V is the relative collision velocity of the two agglomerates (m / s), and κ is a function of the particle Poisson's ratio and Young's modulus, which is calculated as follows: Where v is Poisson's ratio and E is Young's modulus (GPa).

[0085] (4) In the solution set obtained in step (3), find the optimal solution that satisfies the aggregate size restriction condition in the cement precalciner; the aggregate size restriction condition in the cement precalciner is: the size of the aggregate is larger than the particle size d of the cement particles. p And smaller than the inner diameter d of the cement precalciner t That is, d a ∈(d p , d t );

[0086] (5) Based on the optimal solution obtained in step (4) and the true velocity u of the gas in the spatial element obtained in step (2), g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g , calculate the drag coefficient;

[0087] The calculation model of the drag coefficient is shown in formula (5):

[0088]

[0089] In formula (5), C D represents the drag coefficient of the aggregate, ρ g Indicates gas density (kg / m 3 ); s represents the solid content, d a represents the steady-state equivalent agglomerate diameter (m), g represents the gravitational acceleration (m / s 2 ); is the gas velocity, represents the particle velocity and β represents the unit volume drag coefficient of the agglomerate.

[0090] Among them C D2 Satisfying formula (7):

[0091]

[0092] (6) replacing the original drag coefficient in the mass conservation equation, momentum conservation equation and energy conservation equation in step (2) with the drag coefficient obtained in step (5), and looping steps (2) to (5) to perform iterative calculation until an iterative termination condition is reached, thereby obtaining a corrected drag coefficient;

[0093] The condition for terminating the iteration is that the velocity distribution, concentration distribution and temperature distribution satisfy the convergence conditions of the mass conservation equation, momentum conservation equation and energy conservation equation.

[0094] Comparative Example 1

[0095] This comparative example provides a method for measuring flow parameters in a cement precalcining furnace, and the measuring method comprises the following steps:

[0096] (1) Initialize the flow field and boundary conditions according to the physical parameters of the fluid and operating conditions;

[0097] (2) The dual-fluid model of the direct coupling uniform drag model is used to calculate the mass conservation equation, momentum conservation equation and energy conservation equation in each spatial element to obtain the velocity distribution, concentration distribution and temperature distribution in the spatial element; the velocity distribution includes the true velocity u of the gas in the spatial element. g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g .

[0098] Application Example 1

[0099] This application example applies the method for measuring raw material dispersion and temperature distribution in a cement precalciner provided in the embodiment to a pilot-scale cement precalciner.

[0100] Calculation tools: general platform provided by commercial CFD software ANSYS Fluent.

[0101] Fluid physical parameters and operating conditions: The average particle size of raw material particles is 19.5μm, and the raw material density is 2450kg / m 3 The feed rate is 0.139 kg / s and the feed temperature is 28.5 °C. The superficial velocity of the gas is 0.6 m / s and the inlet temperature is 78 °C.

[0102] Precalciner size and structure: The pilot-scale cement precalciner is a vertical cylinder with a height of 6.1m and a diameter of 700mm. There is no additional structure such as necking. A riser with a diameter of 400mm is connected to the bottom of the cylinder. The side of the riser is connected to a hot air pipe, and the angle of the two elbows on the hot air pipe is 90°. The pipe provides hot air to the system through a heat exchanger. There is a spreading box in the middle of the container, which is responsible for sending cement raw material particles into the precalciner.

[0103] The prediction method comprises the following steps:

[0104] (1) The measurement method of raw material dispersion and temperature distribution in the cement precalciner provided in Example 1 is woven into an interface program to replace the method inside the software;

[0105] (2) Construct a 1:1 geometric structure for the reactor, such as Figure 3 As shown, the calculation model is selected as the dual-fluid model under dual Euler coordinates; secondly, the temperature is set and the particle and gas properties are set according to the actual physical property system; the pre-decomposition furnace is initially set to a particle-free static flow. The hot air enters the riser from the hot air pipe, and then enters the pre-decomposition furnace from the riser; the low-temperature raw material particles are sent into the pre-decomposition furnace from the spreading box through pneumatic transport, and the particles are mixed with the upward hot air passing through, move upward and are heated; finally, the mixed air and raw material particles are discharged through the top pipe;

[0106] (3) The interface file for calculating the drag coefficient in step (1) is imported and compiled and run. The calculation is performed in a time-dependent dynamic simulation mode, and the total duration of the cycle calculation is 20 seconds.

[0107] Application Comparative Example 1

[0108] In this application example, the measurement method of raw material dispersion and temperature distribution in a cement precalciner provided in the comparative example is applied to a pilot-scale cement precalciner. The application method is the same as that in application example 1 except that step (1) is not performed and the uniform drag coefficient is directly adjusted.

[0109] The comparison diagram of the predicted results of the gas temperature distribution in the pilot-scale precalcining furnace in the application examples and the comparative examples of the present invention and the experimental values ​​is shown in FIG. Figure 4As shown (the upper and lower parts represent the distribution diagrams of different axial positions), it can be seen from the figure that the method provided in the application example predicts the gas temperature distribution in the pre-decomposition furnace by adopting the method provided in the embodiment. Compared with the application of the comparative example using the method provided in the comparative example to predict, for the 0° line and the 90° line of multiple axial positions, the gas temperature distribution calculated by the application example is consistent with the experimental value better, and is more in line with the actual operating state; while the gas temperature distribution obtained by the application of the comparative example is inconsistent with the actual situation, which shows that the method provided by the present invention combines the agglomeration structure drag model with the dual fluid model, and the particle dispersion and temperature distribution in the pre-decomposition furnace calculated are more consistent with the actual situation.

[0110] In summary, the method for measuring the dispersion and temperature distribution of raw materials in a cement predecomposition furnace provided by the present invention combines the agglomerate structure drag model with the two-fluid model. It only needs to construct a drag correction model based on the steady-state equivalent agglomerate diameter equation, and no longer directly analyzes the van der Waals forces between particles and tracks the dynamic changes of raw material agglomerates. Not only is the calculation process simpler, but it also improves the calculation accuracy of traditional predecomposition furnaces, and is more conducive to the design and scale-up of predecomposition furnaces.

[0111] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for measuring flow parameters in a cement precalciner, characterized in that: The measuring method comprises: (1) Initialize the flow field and boundary conditions according to the physical parameters of the fluid and operating conditions; (2) The two-fluid model is used to calculate the mass conservation equation, momentum conservation equation and energy conservation equation in each spatial element to obtain the velocity distribution, concentration distribution and temperature distribution in the spatial element; the velocity distribution includes the true velocity u of the gas in the spatial element. g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g ; (3) According to the inner diameter d of the cement precalciner t and the true velocity u of the gas in the space element g , the solution set satisfying the steady-state equivalent agglomerate diameter equation is calculated; (4) in the solution set obtained in step (3), finding the optimal solution that satisfies the aggregate size restriction condition in the cement precalciner; (5) Based on the optimal solution obtained in step (4) and the true velocity u of the gas in the spatial element obtained in step (2), g 、The real speed u of the solid in the space element p and the average void fraction ε in the microelement g , calculate the drag coefficient; (6) Substituting the drag coefficient obtained in step (5) for the original drag coefficient in the mass conservation equation, momentum conservation equation and energy conservation equation in step (2), and looping steps (2) to (5) to perform iterative calculation until the iteration termination condition is reached, thereby obtaining a corrected drag coefficient.

2. The measuring method according to claim 1, characterized in that: The calculation in step (2) is performed using a two-fluid model calculation code or commercial computational fluid dynamics software; Preferably, the commercial computational fluid dynamics software includes any one of ANSYS CFX, ANSYS Fluent, Phoenics, STAR-CD, Barracuda, OpenFOAM or MFIX, or a combination of at least two thereof.

3. The measuring method according to claim 2, characterized in that: The establishment of the steady-state equivalent agglomerate diameter equation in step (3) includes: when the aggregation rate and the crushing rate of the agglomerates reach equilibrium, the particle size distribution of the agglomerates in the cement precalciner is used as the equivalent agglomerate particle size, and the force balance equation is used as a constraint condition.

4. The measuring method according to any one of claims 1 to 3, characterized in that: The constraint condition in the steady-state equivalent agglomerate diameter equation in step (3) is shown in formula (1): F g +F v =F d，a +F c Formula (1); In formula (1), F g represents the gravity of the aggregate, F v represents the van der Waals force between aggregates, F d,a The drag force on the aggregates, F c Represents the collision force between agglomerates.

5. The measuring method according to claim 4, characterized in that: The van der Waals force F between the aggregates in step (3) v The calculation formula is shown in formula (2): In formula (2), H is the Hamaker coefficient, δ is the separation distance between two agglomerates, is the ratio of the average diameters of the two aggregates; Preferably, under steady-state conditions, define Preferably, the drag force F on the agglomerate is d,a The calculation formula is shown in formula (3): The ρ in formula (3) g represents the gas density, u slip,a is the apparent slip velocity of the agglomerates, d a represents the steady-state equivalent aggregate diameter, ε g,a Indicates the porosity of the aggregate, C D1 represents the drag coefficient of a single particle; Preferably, the collision force F between the agglomerates in step (3) is c The calculation formula is shown in formula (4): In formula (4), V is the relative collision velocity of the two aggregates, ρ a is the density of the agglomerate, κ is a function of the particle Poisson's ratio and Young's modulus, and its calculation formula is Where v is Poisson's ratio and E is Young's modulus.

6. The measuring method according to claim 4 or 5, characterized in that: The particle size of the cement material in the cement pre-decomposition furnace ranges from 0.3 to 500 μm.

7. The measuring method according to any one of claims 1 to 6, characterized in that: The size restriction condition of the aggregates in the cement precalciner in step (4) is: the size of the aggregates is larger than the particle size d of the cement particles. p And smaller than the inner diameter d of the cement precalciner t .

8. The measuring method according to any one of claims 1 to 7, characterized in that: The calculation model of the drag coefficient in step (5) is shown in formula (5): In formula (5), C D 2 represents the drag coefficient of the particle group, ρ g Indicates gas density; ε s represents the solid content, d a represents the steady-state equivalent agglomerate diameter, g represents the gravitational acceleration; is the gas velocity, represents the particle velocity, β wenyu (d a ) represents the unit volume drag coefficient of the agglomerate.

9. The measuring method according to any one of claims 1 to 8, characterized in that: The condition for terminating the iteration in step (6) is that the velocity distribution, concentration distribution and temperature distribution satisfy the convergence conditions of the mass conservation equation, momentum conservation equation and energy conservation equation.

10. A readable storage medium, characterized in that: The readable storage medium stores a program written according to the method for measuring flow parameters in a cement precalcining furnace according to any one of claims 1 to 9.

Images