CN110029198B - Computer calibration method for cooling effect of blast furnace cooling system - Google Patents
Computer calibration method for cooling effect of blast furnace cooling system Download PDFInfo
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Abstract
The invention belongs to the field of blast furnace cooling systems, is suitable for the aspect of judging the excellence of the cooling capacity of the blast furnace cooling system, and particularly relates to a computer calibration method of the cooling effect of the blast furnace cooling system, wherein the method adopts the cooling intensity or the cooling efficiency of a blast furnace to calibrate the cooling effect of the blast furnace cooling system; wherein the cooling intensity is calculated by the temperature ratio of the hot surface temperature of the cooling wall under an ideal condition to the hot surface temperature of the cooling wall under an actual condition; the higher the temperature ratio, the better the cooling effect of the blast furnace cooling system. The method directly aims at the temperature of the hot surface of the cooling wall, which is a physical quantity capable of reflecting the intrinsic cooling capacity of the cooling system, and takes the temperature of the hot surface of the cooling wall as a research object, so that the method is simple and clear and has great significance in practicability; the method establishes a unified standard for quantitative comparative analysis of the cooling capacity of different blast furnace cooling systems in the future, and lays a solid foundation for the subsequent deep analysis of the cooling capacity of the blast furnace cooling systems.
Description
Technical Field
The invention belongs to the field of blast furnace cooling systems, is suitable for judging the excellence of the cooling capacity of a blast furnace cooling system, and particularly relates to a computer calibration method for the cooling effect of the blast furnace cooling system.
Background
The blast furnace cooling system has important significance for ensuring the smooth operation of the blast furnace and realizing the long service life of the blast furnace. Therefore, a quantitative measure of the cooling capacity of each cooling system is of great importance to further understand the nature of the cooling system of the blast furnace. However, there are many factors that affect the cooling capacity of a blast furnace cooling system, and there is no uniform measure so far.
The earliest analyses of the cooling intensity of blast furnaces were based on single-layer flat plate steady-state heat transfer, and thus, qualitative analyses of the cooling intensity of blast furnaces were performed. The expression is as follows:
in the formula: q-Heat transfer amount per unit time, J/(s.m)2)；
δ — plate thickness, m;
a-heat transfer area perpendicular to the direction of heat flow, m2；
t1，t2-temperature of the surface on both sides of the plate, K;
λ -heat transfer coefficient, W/(m.K);
due to the change of gas flow in the blast furnace, the cooling of the blast furnace is not substantially steady heat transfer, but the steady heat transfer is regarded as a case where the change is small in a certain period of time. For unsteady state heat transfer, the following formula is commonly used:
the physical meaning of this formula is: rate of change of temperature t water time T at a point in the furnace
Temperature gradient from the point
Rate of change in x-direction
In direct proportion, the proportionality constant is the thermal conductivity of the furnace wall. It is also a temperature gradient at all.
The analysis of the cooling intensity of the blast furnace is based on the multi-layer flat plate steady-state heat transfer. The heat transfer of the blast furnace body can be regarded as the heat transfer of a multi-layer flat plate consisting of a slag crust, a furnace lining and a smooth cooling wall, and the heat transfer equation is as follows:
wherein q represents heat flux intensity, S1、S2Represents the thickness of the slag crust lining, lambda1、λ2、λ3Representing the coefficients of heat conductivity of slag crust, furnace lining and cooling wall, a representing the thickness of the center line of the water pipe of the cooling wall from the hot surface thereof, k representing the heat release coefficient of the cooling medium, d representing the diameter of the cooling water pipe, L representing the pipe interval of the cooling wall, and T representing the heat transfer coefficient of the cooling medium1、T2Representing the average temperature of the inner surface of the slag crust and the cooling water.
In conclusion, the heat transfer process of each layer is dependent on the temperature gradient, and the temperature gradient is difficult to calculate accurately in the blast furnace practice; in addition, no uniform quantitative standard exists for the cooling capacity of the blast furnace cooling system, and the deep research on the cooling system is not facilitated.
In addition, in the cooling system of the blast furnace, different types of staves have great differences in their structures; the cooling structure of each part of the blast furnace with the same furnace volume grade or different furnace volume grades is different; the water supply modes of cooling systems of different blast furnaces are also greatly different; this results in differences in the cooling capacity of the different blast furnace cooling systems.
In the prior art, the standard of the cooling capacity of a cooling system of a blast furnace is that the blast furnace is used as a core, namely whether a furnace body of the blast furnace can be effectively cooled; however, such criteria can only be explained: for a certain blast furnace, the cooling capacity of the cooling system of the blast furnace is good, and the comparison of the cooling capacities of different blast furnace cooling systems has no unified standard.
Disclosure of Invention
In order to solve the problems, the invention provides a computer calibration method for the cooling effect of a blast furnace cooling system, which defines two physical quantities of the cooling intensity and the cooling efficiency of the blast furnace cooling system, can calibrate the cooling effect of the blast furnace cooling system well, and the higher the cooling intensity/the cooling efficiency is, the better the cooling effect of the blast furnace is.
The invention is realized by the following technical scheme:
a computer calibration method for the cooling effect of a blast furnace cooling system is disclosed, which adopts the cooling intensity or cooling efficiency of a blast furnace to calibrate the cooling effect of the blast furnace cooling system;
the cooling intensity is calculated by the temperature ratio of the hot surface temperature of the cooling wall under an ideal condition to the hot surface temperature of the cooling wall under an actual condition; the higher the temperature ratio, the better the cooling effect of the blast furnace cooling system.
Further, the ratio of the hot surface temperature of the cooling wall under the ideal condition to the hot surface temperature of the cooling wall of the blast furnace under the actual condition is expressed by the following formula:
wherein I is the cooling intensity, TidealThe hot surface temperature of the blast furnace cooling wall under ideal conditions is expressed in K, TactualThe temperature of the hot surface of the cooling wall of the blast furnace under actual conditions is expressed in K.
Further, when the cooling effect of the blast furnace cooling system is calibrated by adopting the cooling intensity, the blast furnace cooling system is regarded as a multi-layer flat plate heat transfer consisting of a furnace lining, a packing layer, a smooth surface cooling wall and the like; the method comprises the following steps:
Further, the parameters in the step 1 include the size of the cast iron cooling wall, the thickness of a brick lining at the end of the campaign, the heat conductivity coefficient of the brick lining, the thickness of a packing layer, the heat conductivity coefficient of the packing layer, the pipe diameter of a water pipe of the cooling wall, the distance between the water pipes, the temperature of molten iron, the heat exchange coefficient of the molten iron and a lining hot surface, the water flow speed, the heat conductivity of water, the specific heat capacity of water, the density of water, the kinematic viscosity of water, the heat conductivity of a pipe wall of the water pipe, the coating thickness, the coating heat conductivity, the air gap thickness, the gas heat conductivity in an air gap, the heat conductivity of the cast iron cooling wall, the effective distance between the.
Further, in the heat transfer of the multi-layer flat plate, the thermal conductivity of each layer is assumed to be unchanged in the heat transfer process; the heat transfer formula is:
wherein q is the heat flow intensity, λ is the thermal conductivity, x is the direction parallel to but opposite to the heat flow transfer,
△ T is the temperature difference between two media and R is the total thermal resistance of the two media and the flat plate between the two media.
Further, the specific content of step 2 is:
step 2.1, calculating the heat flow intensity q of the blast furnace along the radial direction under the ideal condition by adopting a single couple method or a double couple method in combination with the formula (3)ideal: the temperature T 'of the cooling water supplied to the stave is set to be a desired temperature'IntoThe total thermal resistance R between the molten iron in the blast furnace and the cooling water is equal to the temperature of the outlet waterAComprises the following steps:
wherein, 1/α1Is the thermal resistance of the convective heat transfer process between the molten iron in the furnace and the brick lining, sigma Li/λ ι1/α sum of thermal resistances of furnace lining, filler layer and smooth cooling wall2For cooling water and coldThermal resistance in the convective heat transfer process between the walls of the cooling wall pipes;
substituting the effluent temperature, the molten iron temperature and the total thermal resistance between the molten iron and the cooling water under the ideal conditions into formula (3) to obtain:
wherein, △ TAThe difference between the temperature of molten iron and the temperature of cooling water outlet water;
calculating to obtain the heat flow intensity q of the blast furnace along the radial direction under ideal conditionsideal；
Step 2.2, calculating the hot surface temperature T of the cooling wall under the ideal conditionideal: setting qidealConstant total thermal resistance R of molten iron in the blast furnace to the hot surface of the cooling wallBComprises the following steps:
substituting the water inlet temperature, the heat flow intensity and the total thermal resistance from molten iron to the hot surface of the cooling wall into formula (3) to obtain:
wherein, △ TBThe difference between the temperature of molten iron and the temperature of the hot surface of the cooling wall under an ideal condition;
calculating to obtain the hot surface temperature T of the cooling wall of the blast furnace cooling system under ideal conditionsideal。
Further, the specific content of step 3 is: detecting the outlet temperature T of the cooling water in the stave under actual conditionsGo outThe water inlet temperature under the actual condition is the same as the water inlet temperature under the ideal condition; according to the calculation process of the step 2, calculating the hot surface temperature T of the cooling wall of the blast furnace cooling system under the actual conditionactual。
Further, the cooling effect is the ratio of the heat taken away by the blast furnace cooling system under actual conditions to the heat taken away by the blast furnace cooling system under ideal conditions, and the higher the heat ratio, the better the cooling effect of the blast furnace cooling system is; the formula is as follows:
wherein η is the cooling efficiency, QactualThe unit is J of the heat quantity taken away by a blast furnace cooling system under the actual condition; qidealThe heat quantity taken away by the cooling system under ideal conditions is given by J.
Further, when the cooling efficiency is adopted to calibrate the cooling effect of the blast furnace cooling system, the blast furnace cooling system is regarded as a multi-layer flat plate heat transfer consisting of a furnace lining, a packing layer, a smooth surface cooling wall and the like; the method comprises the following steps of 1:
s2, the heat transfer of the blast furnace cooling system is a one-dimensional heat transfer process along the radial direction, and the heat quantity which can be taken away by the blast furnace cooling system under the actual condition is calculated according to the parameters obtained in the step 1 as follows:
Qactual＝cmΔT＝cm(Tgo out-TInto)＝cvt·4A1·ρ(TGo out-TInto) Formula (4)
Wherein c is the specific heat capacity of the cooling water, J/(kg. K); m is the mass of cooling water, kg;
v is the water inlet speed of the cooling water, m/s; t-cooling time, s;
A1the cross-sectional area, m, of each cooling water pipe2；
Rho-density of cooling water, kg/m3；
TGo out-the outlet temperature of the cooling water in the cooling wall, K, under practical conditions;
Tinto-the inlet temperature of the cooling water in the cooling wall, K, under practical conditions;
s3, calculating the heat quantity which can be taken away by the blast furnace cooling system under the ideal condition as follows:
Qideal＝qidealA2t type (5)
Wherein q isidealIn an ideal state, the blast furnace has a heat flow intensity (heat flux) in the radial direction, J/(s · m)2)；
A2Effective contact area, m, of each cooling wall with the blast furnace body2；
t-cooling time, s;
s4, calculating the cooling efficiency of the blast furnace: q obtained from S2 and S3actualAnd QidealIn place of formula (2), the cooling efficiency η of the blast furnace cooling system is obtained as shown in formula (6) below:
another object of the present invention is to provide a computer program for implementing the computer calibration method for cooling effect of the cooling system of a blast furnace.
Another object of the present invention is to provide an information processing terminal that realizes the above-mentioned computer calibration method for the cooling effect of a blast furnace cooling system.
It is another object of the present invention to provide a computer-readable storage medium comprising instructions which, when run on a computer, cause the computer to perform the above-described computer calibration method for the cooling effect of a blast furnace cooling system.
The invention has the following beneficial technical effects:
1) the blank of the research of the blast furnace cooling system on the aspect of quantitatively measuring the cooling capacity of the blast furnace cooling system is made up.
2) The method directly aims at the temperature of the hot surface of the cooling wall, which is a physical quantity capable of reflecting the intrinsic cooling capacity of the cooling system, and takes the temperature of the hot surface of the cooling wall as a research object, so that the method is simple and clear, and has great significance in practicability.
3) The influence of process parameters such as cooling water quantity, water temperature difference, water inlet temperature, water flow speed, heat flow intensity, water pipe arrangement, cooling water quality and the like is avoided, the appearance characteristic of the final action essence of the hidden cooling system is removed, and the essence characteristic is directly used as a quantification object.
4) The method establishes a unified standard for quantitative comparative analysis of the cooling capacity of different blast furnace cooling systems in the future, and lays a solid foundation for the subsequent deep analysis of the cooling capacity of the blast furnace cooling systems.
Drawings
FIG. 1 is a schematic diagram of the heat transfer of a multi-layer flat plate of a cooling system of a blast furnace in an embodiment of the invention.
FIG. 2 is a schematic diagram of single couple calculation of heat flow in an embodiment of the present invention.
FIG. 3 is a schematic diagram of double couple calculating heat flow in the embodiment of the present invention.
FIG. 4 is a diagram illustrating a simulation result of a temperature field during a heat transfer process of a cooling wall of a cooling system of a blast furnace according to an embodiment of the present invention; wherein, (a) is a round water pipe temperature field distribution diagram, (b) is an elliptical water pipe temperature field distribution diagram, (c) is a small water pipe diameter temperature field distribution diagram, and (d) is a large water pipe diameter temperature field distribution diagram.
FIG. 5 is a line graph showing the temperature variation with the water flow velocity for different specific surface areas in the examples of the present invention.
Description of reference numerals: 1-furnace shell; 2-a filling layer; 3-stave wall body cooling; 4-a water pipe; 5-inlaying bricks; 6-furnace lining.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.
The embodiment provides a computer calibration method for the cooling effect of a blast furnace cooling system, which calibrates the cooling effect of the blast furnace cooling system by adopting the cooling intensity or the cooling efficiency of a blast furnace;
the cooling intensity is calculated by the temperature ratio of the hot surface temperature of the cooling wall under an ideal condition to the hot surface temperature of the cooling wall under an actual condition; the higher the temperature ratio, the better the cooling effect of the blast furnace cooling system.
The ratio of the hot surface temperature of the cooling wall under the ideal condition to the hot surface temperature of the cooling wall of the blast furnace under the actual condition is expressed by adopting a formula as follows:
wherein I is the cooling intensity, TidealThe hot surface temperature of the blast furnace cooling wall under ideal conditions is expressed in K, TactualThe temperature of the hot surface of the cooling wall of the blast furnace under actual conditions is expressed in K.
When the cooling effect of the blast furnace cooling system is calibrated by adopting the cooling intensity, the blast furnace cooling system is regarded as a multi-layer flat plate for heat transfer (as shown in figure 1); the method comprises the following steps:
The parameters in the step 1 comprise the size of the cast iron cooling wall, the thickness of a brick lining at the end of a campaign, the heat conductivity coefficient of the brick lining, the thickness of a packing layer, the heat conductivity coefficient of the packing layer, the pipe diameter of a water pipe of the cooling wall, the distance between water pipes, the temperature of molten iron, the heat exchange coefficient between the molten iron and a hot surface of the lining, the water flow speed, the heat conductivity of water, the specific heat capacity of water, the density of water, the kinematic viscosity of water, the heat conductivity of a pipe wall of the water pipe, the coating thickness, the heat conductivity of a coating, the thickness of an air gap, the heat conductivity of gas in the air gap, the heat conductivity of the cast iron.
In the heat transfer of the multilayer flat plate, the thermal conductivity of each layer is assumed to be unchanged in the heat transfer process; the heat transfer formula is:
wherein q is the heat flow intensity, λ is the thermal conductivity, x is the direction parallel to but opposite to the heat flow transfer,
△ T is the temperature difference between two media and R is the total thermal resistance of the two media and the flat plate between the two media.
The specific content of the step 2 is as follows:
step 2.1, calculating the heat flow intensity q of the blast furnace along the radial direction under the ideal condition by adopting a single couple method or a double couple method in combination with the formula (3)ideal: the temperature T 'of the cooling water supplied to the stave is set to be a desired temperature'IntoThe total thermal resistance R between the molten iron in the blast furnace and the cooling water is equal to the temperature of the outlet waterAComprises the following steps:
wherein, 1/α1Is the thermal resistance of the convective heat transfer process between the molten iron in the furnace and the brick lining, sigma Li/λ ι1/α sum of thermal resistances of furnace lining, filler layer and smooth cooling wall2Thermal resistance in the process of convective heat exchange between cooling water and the wall of the cooling wall;
substituting the effluent temperature, the molten iron temperature and the total thermal resistance between the molten iron and the cooling water under the ideal conditions into formula (3) to obtain:
wherein, △ TAThe difference between the temperature of molten iron and the temperature of cooling water outlet water;
calculating to obtain the heat flow intensity q of the blast furnace along the radial direction under ideal conditionsideal；
Step 2.2, calculating the hot surface temperature T of the cooling wall under the ideal conditionideal: setting qidealConstant total thermal resistance R of molten iron in the blast furnace to the hot surface of the cooling wallBComprises the following steps:
substituting the water inlet temperature, the heat flow intensity and the total thermal resistance from molten iron to the hot surface of the cooling wall into formula (3) to obtain:
wherein, △ TBThe difference between the temperature of molten iron and the temperature of the hot surface of the cooling wall under an ideal condition;
calculating to obtain the hot surface temperature T of the cooling wall of the blast furnace cooling system under ideal conditionsideal。
The specific content of the step 3 is as follows: detecting the outlet temperature T of the cooling water in the stave under actual conditionsGo outThe water inlet temperature under the actual condition is the same as the water inlet temperature under the ideal condition; according to the calculation process of the step 2, calculating the hot surface temperature T of the cooling wall of the blast furnace cooling system under the actual conditionactual。
The cooling effect is the ratio of the heat quantity taken away by the blast furnace cooling system under the actual condition to the heat quantity taken away by the blast furnace cooling system under the ideal condition, and the higher the heat quantity ratio is, the better the cooling effect of the blast furnace cooling system is; the formula is as follows:
wherein η is the cooling efficiency, QactualThe unit is J of the heat quantity taken away by a blast furnace cooling system under the actual condition; qidealThe heat quantity taken away by the cooling system under ideal conditions is given by J.
When the cooling efficiency is adopted to calibrate the cooling effect of the blast furnace cooling system, the blast furnace cooling system is regarded as a multi-layer flat plate for heat transfer (as shown in figure 1); the method comprises the following steps of 1:
s2, the heat transfer of the blast furnace cooling system is a one-dimensional heat transfer process along the radial direction, and the heat quantity which can be taken away by the blast furnace cooling system under the actual condition is calculated according to the parameters obtained in the step 1 as follows:
Qactual＝cmΔT＝cm(Tgo out-TInto)＝cvt·4A1·ρ(TGo out-TInto) Formula (4)
Wherein c is the specific heat capacity of the cooling water, J/(kg. K); m is the mass of cooling water, kg;
v is the water inlet speed of the cooling water, m/s; t-cooling time, s;
A1the cross-sectional area, m, of each cooling water pipe2；
Rho-density of cooling water, kg/m3；
TGo out-the outlet temperature of the cooling water in the cooling wall, K, under practical conditions;
Tinto-the inlet temperature of the cooling water in the cooling wall, K, under practical conditions;
s3, calculating the heat quantity which can be taken away by the blast furnace cooling system under the ideal condition as follows:
Qideal＝qidealA2t type (5)
Wherein q isidealIn an ideal state, the blast furnace has a heat flow intensity (heat flux) in the radial direction, J/(s · m)2)；
A2Effective contact area, m, of each cooling wall with the blast furnace body2；
t-cooling time, s;
s4, calculating the cooling efficiency of the blast furnace: q obtained from S2 and S3actualAnd QidealIn place of formula (2), the cooling efficiency η of the blast furnace cooling system is obtained as shown in formula (6) below:
example 1
In this embodiment, the method for calibrating the cooling intensity and the cooling efficiency of the cooling system of the blast furnace is specifically as follows:
(1) setting of relevant parameters
The cooling process of the blast furnace can be regarded as multi-layer flat plate heat transfer consisting of a furnace lining, a filler layer, a coating, an air gap layer, a smooth cooling wall and the like (as shown in fig. 1, fig. 1 only shows the partial layers of the furnace lining, the filler layer and the like, and the furnace lining, the filler layer, the coating, the air gap layer and the smooth cooling wall are all made of existing materials). Under the condition that the size of the cooling wall is certain, the cooling specific surface area is equal to the ratio of the outer perimeter of the cooling water pipe to the distance between the water pipes, the cooling wall made of copper is taken as a research object to perform example calculation, and values of some parameters are reasonably set according to actual conditions for convenience of calculation.
Size of cast iron cooling wall: 2500mm × 900mm × 160 mm;
the thickness of the brick lining at the end of the campaign: delta1＝300mm；
Brick lining thermal conductivity coefficient: lambda [ alpha ]1＝12W/(m·K)；
Thickness of the packing layer: delta2＝40mm；
Heat conductivity coefficient of the packing layer: lambda [ alpha ]2＝17W/(m·K)；
Pipe diameter of cooling wall water pipe: phi 76X 6mm (D)0＝76mm，d0＝64mm)；
The distance between the water pipes: delta3＝240mm；
Temperature of molten iron: t is0＝1500℃；
Heat exchange coefficient of molten iron and lining hot surface: h is0＝90W/(m2·K)；
Water flow rate: upsilon is 1.5 m/s;
thermal conductivity of water: λ is 0.6W/(m · K);
specific heat capacity of water: cp＝4.2×103J/(kg·℃)；
Density of water: ρ 1.0 × 103kg·m3；
Kinematic viscosity of water: nu 1.006 x 10-6m2/s；
Thermal conductivity of water pipe wall: lambda [ alpha ]w＝50W/(m·K)；
Coating thickness: deltac＝0.2mm；
Thermal conductivity of the coating: lambda [ alpha ]c＝0.8W/(m·K)；
Thickness of air gap: deltag＝0.15mm；
Thermal conductivity of gas in air gap: lambda [ alpha ]g＝0.0385W/(m·K)；
Thermal conductivity of copper cooling wall: lambda [ alpha ]k＝380W/(m·K)，
Effective distance between the hot surface of the cooling wall and the hot surface of the air gap layer: deltak50mm (cooling wall thickness H160 mm, water pipe external diameter D)0＝76mm，
)
The water inlet temperature is as follows: t isInto＝30℃；
Water outlet temperature: t isGo out＝31℃；
(2) Calculation of thermal resistance of each layer in heat transfer process
A, heat resistance R of convective heat transfer between the inner surface of the water pipe and cooling wateraCalculated using equation ①:
wherein α is the convective heat transfer coefficient between the inner surface of the water pipe and the cooling water, W (m)2·K)-1；d0Is the water pipe outer diameter equivalent diameter m; diM. for the equivalent diameter of the inner diameter of the water tube, since the cooling water is forced convection heat transfer, α is calculated using equation ②:
Nu＝αdi/λ＝0.023(υdi/ν)0.8(ν/α)0.4
in the formula, upsilon is the flow velocity of cooling water in the water pipe, m.s-1(ii) a λ is the thermal conductivity of water, W (m.K)-1；CpSpecific heat capacity of water, J. (kg. degree. C.)-1(ii) a Rho is the density of water, kg · m-3(ii) a v is the kinematic viscosity of water, m2·s-1Substituting the parameters into equation ② yields:
the calculated α value was substituted into equation (1) to obtain:
b thermal resistance R of cooling wall in heat transfer processkCalculated using equation ③:
Rk＝δk/λkformula ③
In the formula, deltak-the effective distance, m, of the hot side of the stave from the hot side of the air gap layer; lambda [ alpha ]kThermal conductivity of cast iron staves, W (m.K)-1(ii) a Substituting the relevant data to obtain:
Rk＝0.05/380＝1.3158×10-4
c thermal resistance R of brick lining in heat transfer process1Calculated using equation ④:
R1＝δ1/λ1formula ④
In the formula, delta1-brick lining thickness, m; lambda [ alpha ]1Thermal conductivity of the brick lining, W (m. K)-1(ii) a Substituting the relevant data to obtain:
R1＝0.3/12＝0.025
d thermal resistance R of packing layer in heat transfer process2Calculated using equation ⑤:
R2＝δ2/λ2formula ⑤
In the formula, delta2-the thickness of the filler layer, m; lambda [ alpha ]2Thermal conductivity of the packing layer, W (m.K)-1(ii) a Substituting the relevant data to obtain:
R2＝0.04/17＝2.353×10-3
e, thermal resistance R of heat exchange process of convection between hot surface of lining of hearth and molten iron0Calculated using equation ⑥:
R0＝1/h0formula ⑥
In the formula, h0-coefficient of heat transfer between molten iron and hot surface of lining, W (m.K)-1(ii) a Under the actual condition, the boundary condition of the heat transfer of the hot surface of the lining by using molten iron is closer to the reality than the given temperature, and the heat transfer coefficient h0Related to smelting strength and internal molten iron near-wall circulation strength, a fixed value h is temporarily selected for convenience090W/(m2 · K). Substituting the relevant data to obtain:
R0＝1/90＝0.01111
in summary, the total thermal resistance R of the whole heat transfer process from the cooling water to the molten iron in the furnace is as follows:
R＝Ra+Rk+R0+R1+R2＝0.03860
(3) calculating the Cooling intensity
Ideally, the stave can be viewed as an infinite water area, i.e., the temperature of the cooling water remains substantially constant during the entire heat transfer process, and is the same as the temperature of the incoming water, so that under ideal conditions, the hot side temperature of the stave is the same as the temperature of the incoming water, i.e.: t isideal＝TInto＝30℃。
Under practical conditions, the total heat resistance R of the whole heat transfer process from cooling water to molten iron in the furnace is 0.038601, and the temperature of a water outlet is TGo outAt 31 deg.C, the temperature of molten iron is T01500 ℃, so the heat flux intensity q of the whole process is highactualComprises the following steps:
under the actual condition, the hot surface temperature of the cooling wall is TactualThe total thermal resistance from the hot surface of the cooling wall to molten iron is R through the heat transfer process of the packing layer, the heat transfer process of the brick lining and the heat convection process of the hot surface of the lining of the furnace hearth and the molten ironT＝0.0384634。
Tactual＝T0-qactualRT＝1500-38056.01×0.0384634＝36.24℃
Thus according to the definition of cooling intensity:
that is to say the cooling intensity of the cooling system under this actual condition is 0.8278. Under certain conditions, the greater the cooling intensity, the greater the cooling capacity of the cooling system.
2. Algorithm of cooling efficiency
Under actual conditions, if the heat transfer of the blast furnace cooling system is a one-dimensional radial heat transfer process, the heat quantity taken away by cooling water of the cooling system is calculated to be Qactual：
Qactual＝CpmΔT＝cm(TGo out-TInto)＝Cpvt·4A1·ρ(TGo out-TInto)
The size of the water inlet speed, the density of the cooling water, the cross-sectional area of the water inlet pipe, the specific heat capacity of the cooling water and the water inlet temperature of the cooling water must be determined before calculation. These values all require actual measurement, and both data accuracy and precision are required. Wherein SGRepresents the sum of the cross-sectional areas of the cooling water pipes of all the staves in the circumferential direction of the blast furnace, the sum being obtained by: the cross section area A of each water pipe can be calculated by phi 76 multiplied by 6mm1＝ 3.22×10-3m2Then 4A1＝0.01288m2(ii) a Measuring the outlet water temperature T by a measuring methodGo out＝ 31℃。
Under ideal conditions, let the quantity of heat taken away be QidealThen the expression is:
Qideal＝qidealA2t
in the above formula A2The effective contact area between the cooling wall of the blast furnace and the furnace body of the blast furnace is shown, and when the actual effective contact area between the cooling wall of the blast furnace and the furnace body of the blast furnace is calculated, precise instruments and strict methods are required to carry out detailed measurement so as to ensure the referential property of the calculation result. A. the2The basic dimensions of the cooling wall can be: the contact area A is calculated to be 2500mm multiplied by 900mm multiplied by 160mm2＝2.5m×0.9m＝2.25m2。
And because only three processes of brick lining heat transfer process, packing layer heat transfer process and hearth lining hot surface and molten iron convection heat transfer process are adopted under ideal conditions, the total thermal resistance is as follows: r0+R1+R20.0384634, the heat flow intensity is:
summing the calculated data and defining the resulting Q based on cooling efficiencyactualAnd QidealSubstitution into
The formula:
thereby obtaining the cooling efficiency of the blast furnace cooling system.
The cooling efficiency of the cooling system is therefore 94.36%.
Claims (8)
1. A computer calibration method for the cooling effect of a blast furnace cooling system is characterized in that the method adopts the cooling intensity or the cooling efficiency of a blast furnace to calibrate the cooling effect of the blast furnace cooling system;
the cooling intensity is calculated by the temperature ratio of the hot surface temperature of the cooling wall under an ideal condition to the hot surface temperature of the cooling wall under an actual condition;
when the cooling effect of the blast furnace cooling system is calibrated by adopting the cooling intensity, the blast furnace cooling system is regarded as a multi-layer flat plate for heat transfer; the method comprises the following steps:
step 1, measuring parameters of a blast furnace cooling system;
step 2, calculating the hot surface temperature T of the cooling wall of the blast furnace cooling system under ideal conditions by using the parameters measured in the step 1ideal；
Step 3, calculating the hot surface temperature T of the cooling wall of the blast furnace cooling system under the actual condition by using the parameters obtained by measurement in the step 1actual；
Step 4, calculating the cooling intensity of the blast furnace cooling system: the T obtained in the step 2 and the step 3idealAnd TactualCalculating the temperature ratio to finally obtain the cooling intensity of the blast furnace cooling system;
the specific content of the step 2 is as follows:
step 2.1, calculating the heat flow intensity q of the blast furnace along the radial direction under the ideal condition by adopting a single couple method or a double couple method in combination with the formula (3)ideal: the temperature T 'of the cooling water supplied to the stave is set to be a desired temperature'IntoThe total thermal resistance R between the molten iron in the blast furnace and the cooling water is equal to the temperature of the outlet waterAComprises the following steps:
wherein, 1/α1Is the thermal resistance of the convective heat transfer process between the molten iron in the furnace and the brick lining, sigma Li/λι1/α sum of thermal resistances of furnace lining, filler layer and smooth cooling wall2Thermal resistance in the process of convective heat exchange between cooling water and the wall of the cooling wall;
substituting the effluent temperature, the molten iron temperature and the total thermal resistance between the molten iron and the cooling water under the ideal conditions into formula (3) to obtain:
wherein, △ TAThe difference between the temperature of molten iron and the temperature of cooling water outlet water;
calculating to obtain the heat flow intensity q of the blast furnace along the radial direction under ideal conditionsideal；
Step 2.2, calculating the hot surface temperature T of the cooling wall under the ideal conditionideal: setting qidealConstant total thermal resistance R of molten iron in the blast furnace to the hot surface of the cooling wallBComprises the following steps:
substituting the water inlet temperature, the heat flow intensity and the total thermal resistance from molten iron to the hot surface of the cooling wall into formula (3) to obtain:
wherein, △ TBThe difference between the temperature of molten iron and the temperature of the hot surface of the cooling wall under an ideal condition;
calculating to obtain the hot surface temperature T of the cooling wall of the blast furnace cooling system under ideal conditionsideal。
2. The method for computer calibration of cooling effect of a cooling system of a blast furnace according to claim 1, wherein the cooling intensity is formulated as follows:
wherein I is the cooling intensity, TidealThe hot surface temperature of the blast furnace cooling wall under ideal conditions is expressed in K, TactualThe temperature of the hot surface of the cooling wall of the blast furnace under actual conditions is expressed in K.
3. The computer calibration method for the cooling effect of the cooling system of the blast furnace as claimed in claim 1, wherein in the heat transfer of the multi-layer flat plate, the thermal conductivity of each layer is assumed to be unchanged during the heat transfer; the heat transfer formula is:
wherein q is the heat flow intensity, λ is the thermal conductivity, x is the direction parallel to but opposite to the heat flow transfer,
△ T is the temperature difference between two media and R is the total thermal resistance of the two media and the flat plate between the two media.
4. The method for computer calibration of cooling effect of a cooling system of a blast furnace as claimed in claim 1, wherein the specific content of step 3 is: detecting the outlet temperature T of the cooling water in the stave under actual conditionsGo outThe water inlet temperature under the actual condition is the same as the water inlet temperature under the ideal condition; according to the calculation process of the step 2, calculating the hot surface temperature T of the cooling wall of the blast furnace cooling system under the actual conditionactual。
5. The computer calibration method for the cooling effect of the blast furnace cooling system according to claim 1, wherein the cooling effect is the ratio of the heat quantity taken away by the blast furnace cooling system under actual conditions to the heat quantity taken away by the blast furnace cooling system under ideal conditions; the formula is as follows:
wherein η is the cooling efficiency, QactualThe unit is J of the heat quantity taken away by a blast furnace cooling system under the actual condition; qidealFor heat taken away by cooling systems under ideal conditionsAmount, in units of J.
6. The computer calibration method for the cooling effect of the blast furnace cooling system according to claim 5, wherein when the cooling effect of the blast furnace cooling system is calibrated by adopting the cooling efficiency, the blast furnace cooling system is regarded as multi-layer flat plate heat transfer; the method comprises the following steps of 1:
s2, the heat transfer of the blast furnace cooling system is a one-dimensional heat transfer process along the radial direction, the parameters obtained in the step 1 are adopted, and the heat quantity which can be taken away by the blast furnace cooling system under the actual condition is calculated as follows:
Qactual＝cmΔT＝cm(Tgo out-TInto)＝cvt·4A1·ρ(TGo out-TInto) Formula (4)
Wherein c is the specific heat capacity of the cooling water, J/(kg. K); m is the mass of cooling water, kg;
v is the water inlet speed of the cooling water, m/s; t-cooling time, s;
A1the cross-sectional area, m, of each cooling water pipe2；
Rho-density of cooling water, kg/m3；
TGo out-the outlet temperature of the cooling water in the cooling wall, K, under practical conditions;
Tinto-the inlet temperature of the cooling water in the cooling wall, K, under practical conditions;
s3, calculating the heat quantity which can be taken away by the blast furnace cooling system under the ideal condition as follows:
Qideal＝qidealA2t type (5)
Wherein q isidealThe intensity of heat flow in the longitudinal direction of the blast furnace is J/(s.m) in an ideal state2)；
A2Effective contact area, m, of each cooling wall with the blast furnace body2；
S4, calculating the cooling efficiency of the blast furnace: q obtained from S2 and S3actualAnd QidealSubstituted into formula (2) to obtain the blast furnaceThe cooling efficiency η of the cooling system is shown by the following equation (6):
7. an information processing terminal for implementing a computer calibration method of a cooling effect of a blast furnace cooling system according to any one of claims 1 to 6.
8. A computer-readable storage medium, comprising instructions which, when run on a computer, cause the computer to perform a computer calibration method of the cooling effect of a blast furnace cooling system according to any one of claims 1 to 6.
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