A method of calculating heat transfer in a sinter bed

Abstract

The application discloses a method for calculating heat transfer of a sintering material layer, which comprises the following steps: firstly, based on the gas-solid phase temperature-time curves of multiple discrete points in the height direction of the sintering material layer, a heat transfer proportion calculation model of a material layer unit is established, and a general formula for calculating the heat transfer proportion of any material layer unit to a lower material layer unit is derived; and then, based on the heat transfer proportion distribution of each discrete point, a linear interpolation method is adopted to interpolate and reconstruct the discrete heat transfer proportion at any point in the height direction of the sintering material layer, so as to obtain a continuous distribution curve of the heat proportion in the height direction, which provides more accurate theoretical guidance for optimizing the proportioning of coke powder in the height direction of the material layer. Compared with the existing empirical discrete heat transfer proportion which is obtained by summarizing limited working conditions, the application has higher accuracy and stronger universality, and has remarkable economic and social benefits.

Description

Technical Field

[0001] This invention relates to sintering process design technology, specifically to a method for calculating the heat transfer of sintering material layers, belonging to the field of sintering process design and control technology. Background Technology

[0002] In the iron ore blast sintering process, the heat storage effect of the bed often leads to excessive heat in the lower part of the bed, which can easily cause overheating and damage the metallurgical properties of the sinter. How to rationally utilize the heat storage effect of the bed, reduce fuel consumption, and effectively eliminate the effects of overheating has always been one of the challenges in the iron ore blast sintering process. The key to utilizing heat storage is to clearly define the heat transfer capacity of each bed unit and its transfer ratio, thereby optimizing the proportion of coke powder along the bed height. However, the heat storage mechanism and its patterns are determined by the characteristics of the bed reaction process and the gas-solid interaction, making it a complex system variable.

[0003] During the sintering process, the surface fuel is first ignited to form a combustion zone. Then, under the action of the exhaust fan, the combustion zone slowly moves downwards, forming a structural feature consisting of an upper low-temperature sintering zone, a middle high-temperature combustion zone, and a lower drying preheating zone, a super-wet zone, and the original material zone (i.e., the five-zone theory of sintering). The iron ore raw material is melted and sintered during combustion, transferring heat to the incoming cold air. This heat then passes sequentially through the lower material layer, releasing the heat absorbed from the upper high-temperature zone to the lower low-temperature material layer in different proportions, thus preheating the lower material layer and ensuring efficient energy utilization.

[0004] Existing literature and patents make numerous assumptions regarding the heat transfer process in sintered material layer units. However, these assumptions are specific to certain sintering conditions and therefore not universally applicable. For example, these assumptions include: firstly, the maximum heat transfer distance along the height of the sintered material layer is only 200 mm; secondly, the thickness of each material layer unit is limited to approximately 100 mm, and the number of material layer units cannot be flexibly changed; furthermore, the heat transfer ratio in each material layer unit is simply and crudely summarized as 70% absorption in the first 100 mm of material layer and 30% absorption in the last 100 mm of material layer, indicating that heat transfer is not continuous along the unit height, and all of the above data lack theoretical basis and experimental verification. Summary of the Invention

[0005] To address the issues of poor universality and discontinuity in existing calculations of heat transfer processes in sintered material layer units, this invention provides a method for calculating heat transfer in sintered material layers. First, based on the temperature-time curves of the gas-solid phase at multiple discrete points along the height of the sintered material layer, a calculation model for the heat transfer ratio of a single unit is established, deriving a universal formula for calculating the heat transfer ratio from any material layer unit to the lower material layer units. Then, based on the heat transfer ratio distribution at each discrete point, a linear interpolation method is used to reconstruct the discrete heat transfer ratio at any point along the height of the sintered material layer, obtaining a continuous distribution curve of the heat ratio along the height direction.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is specifically as follows:

[0007] A method for calculating heat transfer in a sintering bed, the method comprising the following steps:

[0008] 1) Divide the sintered material layer into multiple material layer units in the height direction, and select discrete points to be measured in each material layer unit.

[0009] 2) During the sintering process, the gas phase and solid phase temperatures at each discrete point to be measured are detected. Then, the heat transfer and heat storage of each material layer unit are calculated based on the temperature difference between the gas phase and solid phase in each material layer unit. Based on this, the heat transfer ratio from the upper material layer unit to the lower material layer unit during the entire sintering process is calculated.

[0010] Preferably, the method further includes:

[0011] 3) Based on the heat transfer ratio of each material layer unit, the heat transfer ratio between any two material layer points in the height direction of the sintering material layer is calculated using the linear interpolation method.

[0012] Preferably, step 2) includes:

[0013] 201) During the sintering process, the gas phase and solid phase temperatures at each discrete point to be measured are detected, and then the gas-solid phase temperature-time curve is plotted based on the detection results.

[0014] 202) The sintering process is divided into multiple consecutive time periods based on the time point corresponding to the intersection of the gas phase temperature curve and the solid phase temperature curve in the gas-solid phase temperature-time curve.

[0015] It should be noted that in this invention, the number of time periods is determined based on the number of material layer units. If the number of material layer units is N, then the number of time periods is (N-1).

[0016] 203) Calculate the heat transfer and heat storage of each material layer unit in each time period based on the temperature difference between the gas phase and the solid phase in each material layer unit, and then calculate the heat transfer ratio from the upper material layer unit to the lower material layer unit in the whole sintering process.

[0017] As a preferred option, step 203) specifically involves:

[0018] 203a) The sintering material layer is divided into N material layer units from top to bottom, and is denoted as the first material layer unit, the second material layer unit, ..., the Nth material layer unit, where N is an integer greater than 1.

[0019] 203b) Within any given time period, based on the principle of convective heat transfer and the temperature difference between the gas and solid phases in each material layer unit, the heat transfer and heat storage of each material layer unit are calculated sequentially from top to bottom. Then, the heat transfer ratio from any material layer unit to the material layer units below it is calculated during the entire sintering process.

[0020] Preferably, within any given time period, the material layer unit with a solid phase temperature higher than the gas phase temperature is designated as the heat transfer unit, denoted as the 1st to (i-1th)th material layer unit, where i is an integer from 2 to N. The calculation model for the heat transfer capacity of the 1st to (i-1th)th material layer unit is then:

[0021]

[0022] In equation (1), Δt(m) is any time interval, and m is an integer from 1 to (N-1). Let be the heat transfer capacity of the f-th material layer unit within the time period m, in kJ, where f is an integer from 1 to (i-1). h is the heat transfer coefficient, ranging from 30 to 150 W / (m²). 2 ·K). A is the heat transfer area, m. 2 . Let be the solid phase temperature of the f-th material layer unit within the time period numbered m, in °C. Let be the gas phase temperature of the f-th material layer unit within the time period numbered m, in °C.

[0023] In this invention, the specific value of h can be determined according to the formula. Nu = 2 + 1.1Pr 1 / 3 Re 2 / 3 , Calculations are performed, where: N u λ is the Nusselt number, a dimensionless number. g d is the thermal conductivity of the gas phase, in W / (m·K); p Pr is the equivalent radius of the mixture, in meters; Re is the Prandtl number, dimensionless; ρ is the gas phase Reynolds number, dimensionless. gThis refers to the gas phase density, in kg / m³. 3 ;v g Airflow velocity, in m / s; μ g This is the dynamic viscosity coefficient, with units of N·s / m. 2 c p,g This is the specific heat capacity of the gas phase, expressed in J / (kg·℃).

[0024] It should be noted that all formulas in this invention were obtained by the inventor based on experimental and engineering applications, and all calculations were obtained by substituting the converted values ​​into the formulas after conversion (after conversion, only the values ​​are substituted into the formulas, not the units; the units are only used to adjust the magnitude of the values).

[0025] Preferably, the material layer unit with a solid phase temperature lower than the gas phase temperature is defined as a heat transfer unit, denoted as the i-th to N-th material layer units. The heat storage calculation model for the i-th to N-th material layer units is as follows:

[0026]

[0027] In equation (2), Let x be the heat storage capacity of the x-th material layer unit within the time period numbered m, in kJ, where x is an integer from i to N. Let be the gas phase temperature of the x-th material layer unit within the time period numbered m, in °C. Let be the solid phase temperature of the x-th material layer unit within the time period numbered m, in °C.

[0028] As a preferred embodiment, the calculation model for the heat transfer ratio from the f-th material layer unit to the x-th material layer unit is as follows:

[0029]

[0030] In equation (3), This represents the heat transfer ratio (i.e., the heat transfer proportion) from the f-th material layer unit to the x-th material layer unit within the time period numbered m. Let be the sum of the heat transferred from the (f+1)th to (x-1)th material layer unit to the xth material layer unit within the time period numbered m, in kJ.

[0031] Preferably, throughout the entire sintering process (including all time periods), the total heat transfer ratio from the f-th layer unit to the x-th layer unit is:

[0032]

[0033]

[0034]

[0035] In equations (4)-(6), This represents the total heat transfer ratio from the f-th material layer unit to the x-th material layer unit over all time periods. The total heat transfer of the f-th material layer unit over all time periods is expressed in kJ. The total heat storage received by the x-th material layer unit from the f-th material layer unit over all time periods is expressed in kJ.

[0036] Preferably, during ideal sintering, the gas-solid phase temperature-time curves of each layer of the sintered material are basically the same. It can be inferred that the heat transfer ratio between any two adjacent layers is consistent, that is, within the time interval Δt(m), the heat transfer ratio from the (i-1)th layer to the ith layer is consistent. The heat transfer ratio from the i-th material layer unit to the (i+1)-th material layer unit Consistent:

[0037]

[0038] Based on the inference that the heat transfer ratio between any two adjacent material layer units is consistent, within the time interval Δt(m), the heat transfer ratio between the first and second material layer units is first calculated based on their respective heat transfer capacity and heat storage capacity. Then, based on the calculated heat transfer ratio and the heat transfer capacity and heat storage capacity of the second and third material layer units, the heat transfer from the first material layer unit to the second material layer unit is calculated, and subsequently, the heat transfer ratio from the first material layer unit to the third material layer unit is calculated. This process is repeated sequentially to calculate the heat transfer ratio between any two material layer units within the time interval Δt(m). Finally, the total heat transfer ratio between any two material layer units throughout the entire sintering process is calculated.

[0039] In this invention, taking the first material layer unit to the i-th material layer unit (the first heat transfer unit) as an example, the heat transfer ratio from the first material layer unit to the i-th material layer unit within the time period Δt(m) is denoted as... Then we have:

[0040]

[0041] In the above formula, This should be understood as the sum of the heat transfer from the second material layer to the (i-1)th unit to the i-th material layer unit during this time period, i.e.:

[0042]

[0043] Furthermore, the total heat transfer ratio from the first material layer unit to the i-th material layer unit is denoted as... Let Δt_all represent all time intervals from the first material layer unit to the i-th material layer unit (i.e., the entire sintering process), then we have:

[0044]

[0045] Assume there are a total of k time intervals (k is an integer of 1-(NI)) during which heat is transferred from the first material layer unit to the i-th material layer unit. The total heat received by the i-th material layer unit from the 1st material layer unit over all time periods. The total heat transfer of the first material layer unit over all time periods is:

[0046]

[0047]

[0048] Then, the downward heat transfer ratio of other material layer units n (n is an integer from 2 to N) can be deduced similarly, resulting in:

[0049]

[0050] It should be noted that in the above calculation process, the heat transfer unit only transfers heat and does not store heat (i.e., the heat storage capacity is considered to be 0), and the heat storage unit only stores heat and does not transfer heat (i.e., the heat transfer capacity is considered to be 0). Generally, except for the first material layer unit which does not store heat, the other material layer units both transfer and store heat, but the two are not carried out simultaneously; generally, heat storage occurs first, followed by heat transfer.

[0051] Preferably, step 3) specifically involves: based on the heat transfer ratio distribution of the discrete points to be measured, using linear interpolation to reconstruct the discrete heat transfer ratio at any point in the height direction, thereby obtaining a continuous distribution curve of the heat ratio in the height direction. The interpolation reconstruction calculation model is as follows:

[0052]

[0053] In equation (8), The heat transfer ratio is the ratio of any point e in the sintered material layer. Let be the known heat transfer ratio of the discrete point j to be measured, where j is the nearest point to the left of point e. Let (j+1) be the known heat transfer ratio at the discrete point (j+1) to be measured, where (j+1) is the point closest to the right of point e. Let height(e) be the height corresponding to any point e in the sintered material layer. Let height(j) be the known height corresponding to the discrete point j to be measured. Let height(j+1) be the known height corresponding to the discrete point (j+1) to be measured.

[0054] In this invention, based on the heat storage mechanism of iron ore raw material being melted and sintered during combustion in the blast sintering process, transferring heat to the incoming cold air, and the cooled air passing through the lower material layer sequentially, releasing the heat absorbed from the upper high-temperature zone to the lower low-temperature material layer in different proportions, this invention establishes a calculation model for the heat transfer ratio of each sintering material layer unit based on the temperature-time curves of the gas-solid phase at multiple discrete points along the height direction of the sintering material layer. This leads to the derivation of a general formula for calculating the heat transfer ratio from each material layer unit to the lower material layer unit. Then, based on the heat transfer ratio distribution at each discrete point, a linear interpolation method is used to reconstruct the discrete heat transfer ratio at any point along the height direction of the sintering material layer, obtaining a continuous distribution curve of the heat ratio along the height direction. This provides precise theoretical guidance for optimizing the proportion of coke powder along the height direction of the material layer.

[0055] In this invention, it should be noted that in the heat transfer ratio calculation model of the sintering material layer unit established based on the gas-solid phase temperature-time curves of multiple discrete points in the height direction of the sintering material layer, when ideal carbon distribution and ideal sintering are achieved, the gas-solid phase temperature curves of each material layer unit are basically the same, and the maximum temperature is equal. Therefore, a reasonable inference can be drawn: that is, the heat transfer ratio between any two adjacent material layer units is almost the same (the heat transfer law from any upper material layer unit to its adjacent lower material layer unit is consistent). This inference is an important basis for the establishment of the heat transfer ratio calculation model of the sintering material layer unit in this invention.

[0056] In this invention, firstly, based on the temperature data of the gas and solid phases at multiple discrete points to be measured in each material layer unit, the intersection point P (e.g., ...) of the gas phase temperature curve and the solid phase temperature curve of each material layer unit is obtained. Figure 2 In P(1)-P(N)), the time t corresponding to each intersection point is obtained (e.g., ... Figure 2 In the middle t(1)-t(N)), each two adjacent intersections are a time period Δt(m) (m is an integer of 1-(N-1)); next, the heat transfer and heat storage of each material layer unit in each time period are calculated in turn, and the heat transfer ratio of the first material layer to each material layer unit below in each time period is calculated accordingly. Finally, the total heat transfer ratio of the first material layer unit to each material layer unit below during the integrated sintering process (t(1)-t(N)) is calculated. Then, the total heat transfer ratio of the second to (N-1) material layer units to each material layer unit below them is calculated in the same way.

[0057] In this invention, based on actual working conditions, the sintering material layer is divided into multiple layer units from top to bottom, and numbered from top to bottom using natural integers from 1 to N. Within each layer unit, suitable discrete points are selected for measurement. During sintering, the gas and solid phase temperatures at each discrete point are detected, and gas-solid phase temperature-time curves are plotted. Then, the total heat transferable by the first layer unit is calculated based on the gas-solid phase temperature difference and convective heat transfer formula. Next, along the downward direction of the sintering material layer height, the total heat absorbed by each layer unit (the sum of heat transfer and heat storage) during sintering is calculated sequentially. Since the heat absorbed by the second layer unit comes entirely from the heat transfer of the first layer unit, the heat transfer ratio from the first layer unit to the second layer unit can be calculated (denoted as ). The heat absorbed by the third material layer unit comes entirely from the heat transfer between the first and second material layer units. Based on the inference that the heat transfer ratio between adjacent material layer units is consistent, and... The total heat transferred from the second material layer unit to the third material layer unit is used to obtain the heat transferred from the second material layer unit to the third material layer unit. This allows us to calculate the heat transferred from the first material layer unit to the third material layer unit and the heat transfer ratio (denoted as ). ); and so on, the proportion of heat transferred from the first material layer unit to each of the lower material layer units can be calculated; and so on, the proportion of heat transferred from the second material layer unit, the third material layer unit, and the (N-1)th material layer unit to the material layer units below them can be calculated.

[0058] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0059] 1. The heat transfer ratio calculation method of the sintering material layer unit proposed in this invention can obtain the heat transfer ratio of any unit at any height. It has continuity and can be applied to any working condition. Compared with the discrete heat transfer ratio summarized by the existing methods for finite working conditions, the method of this invention has higher accuracy and stronger versatility.

[0060] 2. The method for calculating the heat transfer ratio of the sintering material layer unit proposed in this invention has a simple process, high detection and calculation efficiency, and strong accuracy. It provides more accurate theoretical guidance for optimizing the proportion of coke powder in the height direction of the material layer and has significant social and economic benefits. Attached Figure Description

[0061] Figure 1 This is a simplified flowchart of the calculation process of the method described in this invention.

[0062] Figure 2 This is a schematic diagram of the gas-solid phase temperature-time curve and the division of time periods in the method described in this invention.

[0063] Figure 3 This is a gas-solid phase temperature-time curve for application example 1 of the present invention.

[0064] Figure 4 This is a line graph showing the heat transfer ratio from the first material layer unit to the lower material layer units in Application Embodiment 1 of the present invention.

[0065] Figure 5 This is a comparison diagram of the carbon content distribution of each material layer unit obtained by the algorithm of this invention and the traditional existing algorithm. Detailed Implementation

[0066] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0067] Example 1

[0068] A method for calculating heat transfer in a sintering bed, the method comprising the following steps:

[0069] 1) Divide the sintered material layer into multiple material layer units in the height direction, and select discrete points to be measured in each material layer unit.

[0070] 2) During the sintering process, the gas phase and solid phase temperatures at each discrete point to be measured are detected. Then, the heat transfer and heat storage of each material layer unit are calculated based on the temperature difference between the gas phase and solid phase in each material layer unit. Based on this, the heat transfer ratio from the upper material layer unit to the lower material layer unit during the entire sintering process is calculated.

[0071] Example 2

[0072] Repeat Example 1, except that the method further includes:

[0073] 3) Based on the heat transfer ratio of each material layer unit, the heat transfer ratio between any two material layer points in the height direction of the sintering material layer is calculated using the linear interpolation method.

[0074] Example 3

[0075] Repeat Example 2, except that step 2) includes:

[0076] 201) During the sintering process, the gas phase and solid phase temperatures at each discrete point to be measured are detected, and then the gas-solid phase temperature-time curve is plotted based on the detection results.

[0077] 202) The sintering process is divided into multiple consecutive time periods based on the time point corresponding to the intersection of the gas phase temperature curve and the solid phase temperature curve in the gas-solid phase temperature-time curve.

[0078] 203) Calculate the heat transfer and heat storage of each material layer unit in each time period based on the temperature difference between the gas phase and the solid phase in each material layer unit, and then calculate the heat transfer ratio from the upper material layer unit to the lower material layer unit in the whole sintering process.

[0079] Example 4

[0080] Repeat Example 3, except that step 203) is specifically as follows:

[0081] 203a) The sintering material layer is divided into N material layer units from top to bottom, and is denoted as the first material layer unit, the second material layer unit, ..., the Nth material layer unit, where N is an integer greater than 1.

[0082] 203b) Within any given time period, based on the principle of convective heat transfer and the temperature difference between the gas and solid phases in each material layer unit, the heat transfer and heat storage of each material layer unit are calculated sequentially from top to bottom. Then, the heat transfer ratio from any material layer unit to the material layer units below it is calculated during the entire sintering process.

[0083] Example 5

[0084] Repeat Example 4, except that within any given time period, the material layer unit with a solid phase temperature higher than the gas phase temperature is designated as the heat transfer unit, denoted as the 1st to (i-1th)th material layer unit, where i is an integer from 2 to N. The heat transfer capacity calculation model for the 1st to (i-1th)th material layer unit is then as follows:

[0085]

[0086] In equation (1), Δt(m) is any time interval, and m is an integer from 1 to (N-1). Let be the heat transfer capacity of the f-th material layer unit within the time period m, in kJ, where f is an integer from 1 to (i-1). h is the heat transfer coefficient, with a value of 75 W / (m²). 2 ·K). A is the heat transfer area, m. 2 . Let be the solid phase temperature of the f-th material layer unit within the time period numbered m, in °C. Let be the gas phase temperature of the f-th material layer unit within the time period numbered m, in °C.

[0087] Example 6

[0088] Repeat Example 5, except that the material layer unit with a solid phase temperature lower than the gas phase temperature is defined as a heat transfer unit, denoted as the i-th to N-th material layer units. The heat storage calculation model for the i-th to N-th material layer units is then as follows:

[0089]

[0090] In equation (2), Let x be the heat storage capacity of the x-th material layer unit within the time period numbered m, in kJ, where x is an integer from i to N. Let be the gas phase temperature of the x-th material layer unit within the time period numbered m, in °C. Let be the solid phase temperature of the x-th material layer unit within the time period numbered m, in °C.

[0091] Example 7

[0092] Example 6 is repeated, except that the calculation model for the heat transfer ratio from the f-th material layer unit to the x-th material layer unit is as follows:

[0093]

[0094] In equation (3), Let f be the heat transfer ratio from the f-th material layer unit to the x-th material layer unit within the time period m.

[0095] Let be the sum of the heat transferred from the (f+1)th to (x-1)th material layer unit to the xth material layer unit within the time period numbered m, in kJ.

[0096] Example 8

[0097] Example 7 is repeated, except that the total heat transfer ratio from the f-th layer unit to the x-th layer unit during the entire sintering process is:

[0098]

[0099]

[0100]

[0101] In equations (4)-(6), This represents the total heat transfer ratio from the f-th material layer unit to the x-th material layer unit over all time periods. The total heat transfer of the f-th material layer unit over all time periods is expressed in kJ. The total heat storage received by the x-th material layer unit from the f-th material layer unit over all time periods is expressed in kJ.

[0102] Example 9

[0103] Repeat Example 8, except that under ideal sintering conditions, the gas-solid phase temperature-time curves of each material layer unit are basically the same. It can be deduced that the heat transfer ratio between any two adjacent material layer units is consistent, that is, within the time period Δt(m), the heat transfer ratio from the (i-1)th material layer unit to the ith material layer unit is consistent. The heat transfer ratio from the i-th material layer unit to the (i+1)-th material layer unit Consistent:

[0104]

[0105] Based on the inference that the heat transfer ratio between any two adjacent material layer units is consistent, within the time interval Δt(m), the heat transfer ratio between the first and second material layer units is first calculated based on their respective heat transfer capacity and heat storage capacity. Then, based on the calculated heat transfer ratio and the heat transfer capacity and heat storage capacity of the second and third material layer units, the heat transfer from the second material layer unit to the third material layer unit is calculated, and subsequently, the heat transfer ratio from the first material layer unit to the third material layer unit is calculated. This process is repeated sequentially to calculate the heat transfer ratio between any two material layer units within the time interval Δt(m). Finally, the total heat transfer ratio between any two material layer units throughout the entire sintering process is calculated.

[0106] Example 10

[0107] Repeat Example 9, except that step 3) specifically involves: based on the heat transfer ratio distribution of the discrete points to be measured, using linear interpolation, reconstructing the discrete heat transfer ratio at any point in the height direction to obtain a continuous distribution curve of the heat ratio in the height direction. The interpolation reconstruction calculation model is as follows:

[0108]

[0109] In equation (8), The heat transfer ratio is the ratio of any point e in the sintered material layer. Let be the known heat transfer ratio of the discrete point j to be measured, where j is the nearest point to the left of point e. Let (j+1) be the known heat transfer ratio at the discrete point (j+1) to be measured, where (j+1) is the point closest to the right of point e. Let height(e) be the height corresponding to any point e in the sintered material layer. Let height(j+1) be the known height corresponding to the discrete point j to be measured. Let height(j+1) be the known height corresponding to the discrete point (j+1) to be measured.

[0110] Application Example 1

[0111] The heat transfer of the sintering layer was calculated using the method described in Example 10. The total thickness of the sintering layer was 600 mm, and there were 6 layer units. A discrete point was selected in each layer unit. During the sintering process, the gas phase and solid phase temperatures at the 6 discrete points were measured, and gas-solid phase temperature-time curves were plotted. Then, the calculation model of equations (1) to (8) was programmed using MATLAB based on the gas-solid phase temperature-time curves, and the gas-solid phase temperature-time curve data of the layer units obtained from the numerical simulation were imported into a file for example calculation. The calculation results are as follows: the heat transfer ratio from the first layer unit to the second to sixth layer units is 34.22%, 30.29%, 14.74%, 9.49%, and 1.17%, respectively. The remaining heat (approximately 10.09%) is carried away with the emission of sintering exhaust gas.

[0112] The traditional algorithm (with a total heat transfer distance of 200mm between sintering layers, where the first 100mm layer absorbs 70% and the last 100mm layer absorbs 30%) and the novel algorithm of this invention are applied to the carbon distribution optimization calculation, resulting in a comparison diagram of the carbon content distribution in each layer unit. Figure 5 The algorithm of this invention yields a more gradual change in the optimized carbon content, while the optimized carbon content obtained by traditional algorithms drops rapidly in units 1-6 (upper layer), which is inconsistent with reality. The accuracy of the algorithm of this invention depends on the accuracy of the numerical model or the detected temperature data. The numerical simulation results of the sintering process and the experimental results have a high degree of agreement. Therefore, the algorithm model of this invention can obtain a heat transfer ratio and optimized carbon distribution that are more consistent with reality.

Claims

1. A method for calculating heat transfer in a sintering bed, characterized in that: The method includes the following steps: 1) Divide the sintered material layer into multiple material layer units along the height direction, and select discrete points to be measured within each material layer unit; 2) During the sintering process, the gas and solid phase temperatures at each discrete point are measured. Then, based on the temperature difference between the gas and solid phases within each material layer unit, the heat transfer and heat storage of each material layer unit are calculated. This allows for the calculation of the heat transfer ratio from the upper material layer unit to the lower material layer unit throughout the entire sintering process. Specifically: 201) During the sintering process, the gas phase and solid phase temperatures at each discrete point to be measured are detected, and then the gas-solid phase temperature-time curve is plotted based on the detection results. 202) The sintering process is divided into multiple consecutive time periods based on the time points corresponding to the intersection of the gas phase temperature curve and the solid phase temperature curve in the gas-solid phase temperature-time curve. 203) Calculate the heat transfer and heat storage of each material layer unit in each time period based on the temperature difference between the gas phase and the solid phase in each material layer unit, and then calculate the heat transfer ratio from the upper material layer unit to the lower material layer unit during the entire sintering process. 3) Based on the heat transfer ratio of each material layer unit, the heat transfer ratio between any two material layer points in the height direction of the sintering material layer is calculated using the linear interpolation method.

2. The method according to claim 1, characterized in that: Step 203) specifically refers to: 203a) The sintering material layer is divided into N material layer units from top to bottom, and is denoted as the first material layer unit, the second material layer unit, ..., the Nth material layer unit, where N is an integer greater than 1; 203b) Within any time period, based on the principle of convective heat transfer and the temperature difference between the gas phase and the solid phase in each material layer unit, the heat transfer and heat storage of each material layer unit are calculated sequentially from top to bottom, and then the heat transfer ratio from any material layer unit to each material layer unit below it is calculated during the entire sintering process.

3. The method according to claim 2, characterized in that: Within any given time period, the material layer unit with a solid phase temperature higher than the gas phase temperature is designated as the heat transfer unit, denoted as the 1st to (i-1)th material layer unit, where i is an integer from 2 to N; then the calculation model for the heat transfer capacity of the 1st to (i-1)th material layer unit is as follows: （1）； In equation (1), Let m be any time interval, and m be an integer from 1 to (N-1). Let be the heat transfer capacity of the f-th material layer unit within the time period m, in kJ, where f is an integer from 1 to (i-1); h is the heat transfer coefficient, ranging from 30 to 150 W / (m²). 2 ·K); A is the heat transfer area, m 2 ; Let be the solid phase temperature of the f-th material layer unit within the time period numbered m, in °C; Let be the gas phase temperature of the f-th material layer unit within the time period numbered m, in °C.

4. The method according to claim 3, characterized in that: Let the material layer units with solid phase temperatures lower than gas phase temperatures be defined as heat transfer units, denoted as the i-th to N-th material layer units; then the heat storage calculation model for the i-th to N-th material layer units is as follows: （2）； In equation (2), Let x be the heat storage capacity of the x-th material layer unit within the time period numbered m, in kJ, where x is an integer from i to N; Let m be the gas phase temperature of the x-th material layer unit within the time period numbered m, in °C. Let be the solid phase temperature of the x-th material layer unit within the time period numbered m, in °C.

5. The method according to claim 4, characterized in that: The calculation model for the heat transfer ratio from the f-th material layer unit to the x-th material layer unit is as follows: （3）； In equation (3), The heat transfer ratio from the f-th material layer unit to the x-th material layer unit within the time period numbered m; Let be the sum of the heat transferred from the (f+1)th material layer unit to the xth material layer during the time period numbered m, in kJ.

6. The method according to claim 5, characterized in that: During the entire sintering process, the total heat transfer ratio from the f-th layer unit to the x-th layer unit is: （4）； （5） （6）； In equations (4)-(6), This represents the total heat transfer ratio from the f-th material layer unit to the x-th material layer unit over all time periods. The total heat transfer of the f-th material layer unit over all time periods is expressed in kJ. The total heat storage received by the x-th material layer unit from the f-th material layer unit over all time periods is expressed in kJ.

7. The method according to claim 6, characterized in that: Under ideal sintering conditions, the gas-solid phase temperature-time curves of each layer of the sintered material are essentially the same. This leads to the conclusion that the heat transfer ratio between any two adjacent layers is consistent, i.e., in... The heat transfer ratio from the (i-1)th material layer unit to the ith material layer unit within the time period. The heat transfer ratio from the i-th material layer unit to the (i+1)-th material layer unit Consistent: （7）； Based on the inference that the heat transfer ratio between any two adjacent material layer units is consistent, Within a given time period, the heat transfer ratio between the first and second material layer units is first calculated based on their respective heat transfer capacity and heat storage capacity. Then, based on the calculated heat transfer ratio and the heat transfer capacity and heat storage capacity of the second and third material layer units, the heat transfer from the second material layer unit to the third material layer unit is calculated, and subsequently, the heat transfer ratio from the first material layer unit to the third material layer unit is calculated. This process is repeated sequentially to obtain the heat transfer ratio within the specified time period. The heat transfer ratio between any two material layer units within a time period; further calculations are performed to obtain the total heat transfer ratio between any two material layer units throughout the entire sintering process.

8. The method according to any one of claims 1-7, characterized in that: Step 3) Specifically, based on the heat transfer ratio distribution of the discrete points to be measured, a linear interpolation method is used to reconstruct the discrete heat transfer ratio at any point in the height direction, obtaining a continuous distribution curve of the heat ratio in the height direction; the interpolation reconstruction calculation model is as follows: （8）； In equation (8), The heat transfer ratio at any point e in the sintered material layer; Let j be the known heat transfer ratio of the discrete point j to be measured, where j is the point closest to the left end of point e. Let (j+1) be the known heat transfer ratio of the discrete point (j+1) to be measured, where (j+1) is the point closest to the right end of point e. Let e ​​be the height corresponding to any point e in the sintered material layer; The height is the known height corresponding to the discrete point j to be measured; The height is the known height corresponding to the discrete point (j+1) to be measured.

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