Blast furnace cooling schedule calculation and evaluation method

Abstract

The invention relates to the field of blast furnace cooling, and provides a blast furnace cooling schedule calculation and evaluation method in order to facilitate calculation and evaluation of a cooling schedule. Constructing a slag crust thermal load relational expression and a cooling index calculation formula; selecting a slag crust thickness control range and substituting the slag crust thickness control range into a slag crust thermal load relational expression to calculate and obtain a blast furnace target area cooling wall thermal load control range; substituting the thermal load control range of the cooling wall into a cooling index calculation formula to calculate and obtain a cooling degree control index parameter range of the cooling wall in the target area; and calculating an actual cooling degree control index, and if the actual cooling degree control index exceeds the cooling degree control index parameter range, adjusting the cooling water flow and / or the water inlet and outlet temperature difference of the cooling water until the actual cooling degree control index is within the cooling degree control index parameter range. The mode is simple and easy to operate, high in practicability and high in efficiency.

Description

Technical Field

[0001] The invention relates to the field of blast furnace cooling, in particular to a blast furnace cooling system calculation and evaluation method. Background Art

[0002] The purpose of blast furnace cooling is to increase the temperature gradient in the furnace lining, so that the 1150℃ isothermal surface is far away from the blast furnace shell, thereby protecting certain metal structures and concrete components from losing strength, and at the same time making the furnace lining condense into slag skin, protecting or even replacing the furnace lining, so as to obtain a reasonable furnace type and extend the working capacity of the furnace lining and the service life of the blast furnace. Among them, the furnace belly, furnace waist, and the lower furnace wall of the furnace body are within the range of the blast furnace soft melting zone, which belongs to the high heat load area of ​​the blast furnace and is the key part of the blast furnace wall cooling. The selection of cooling system for blast furnace cooling wall in high heat load area, especially the control of water flow and water temperature difference, not only affects the generation and shedding of slag skin in high load area, but also plays a vital role in the safety and longevity of cooling wall. At present, there are few calculation and evaluation methods for blast furnace cooling system, and there is no strict theoretical calculation formula. Blast furnace designers and operators at home and abroad generally determine the corresponding cooling system and parameters by analogy with the same type of blast furnaces that have been put into production. This method has large errors and cannot predict the cooling effect. Summary of the invention

[0003] In order to facilitate the calculation and evaluation of the cooling system, the present application provides a method for calculating and evaluating the cooling system of a blast furnace.

[0004] The technical solution adopted by the present invention to solve the above problems is:

[0005] Calculation and evaluation methods of blast furnace cooling system, including:

[0006] Step 1, collecting the cooling wall slag thickness s, cooling wall heat load data q, cooling water flow L and the inlet and outlet temperature difference Δt of the cooling water in the target area of ​​the blast furnace within a preset time;

[0007] Step 2: Based on the cooling wall heat load data q obtained in step 1 and the corresponding slag skin thickness s, a slag skin heat load relationship is established: s=f(q); based on the cooling wall heat load data q, the cooling water flow rate L and the inlet and outlet temperature difference Δt of the cooling water, a cooling index calculation formula is established: X=y(q), where X is the cooling degree control index, and X=LΔt;

[0008] Step 3: According to the actual demand for slag thickness in the target area of ​​the blast furnace, select the slag thickness control range [s min ,s max ]; Substitute the slag skin thickness control range into the slag skin heat load relationship to calculate the blast furnace target area cooling wall heat load control range [q min ,q max ];

[0009] Step 4: Substitute the cooling wall heat load control range into the cooling index calculation formula to calculate the cooling degree control index parameter range of the cooling wall in the target area [X min , X max ];

[0010] Step 5: Collect the real-time cooling water flow rate and the inlet and outlet temperature difference of the cooling water of the cooling wall in the target area of ​​the blast furnace and calculate the actual cooling degree control index. If the actual cooling degree control index exceeds the cooling degree control index parameter range, it is necessary to adjust the cooling water flow rate and / or the inlet and outlet temperature difference of the cooling water until the actual cooling degree control index is within the cooling degree control index parameter range.

[0011] Furthermore, in step 2, nonlinear regression analysis is used to construct a slag skin heat load relationship.

[0012] Furthermore, the correction coefficient of the regression equation when constructing the slag skin heat load relationship is greater than 95%.

[0013] Furthermore, the heat load relationship of the slag skin is: s = f (q) = a (1-e ( - bq) ) c ; In the formula, s represents the slag skin thickness, q is the cooling wall heat load, and a, b, and c are constants.

[0014] Furthermore, the step 1 further comprises collecting the heat dissipation area F of the i-th cooling wall in the target area of ​​the blast furnace i , the distribution ratio of the total heat dissipated by the blast furnace between the cooling wall and the furnace shell ω, the number of cooling wall layers in the i-th section n i and the specific heat capacity of water, c;

[0015] The step 2 is based on the cooling wall heat load data q, the cooling water flow rate L, the cooling water inlet and outlet temperature difference Δt, the heat dissipation area F of the i-th cooling wall i , the distribution ratio of the total heat lost by the blast furnace between the cooling wall and the furnace shell ω, the number of cooling wall layers in the i-th section n i And the specific heat capacity c of water to construct the cooling index calculation formula.

[0016] Furthermore, in step 2, linear regression analysis is used to construct a cooling index calculation formula.

[0017] Furthermore, the cooling index calculation formula is:

[0018] Furthermore, the step 5 is specifically as follows:

[0019] Collect the real-time cooling water flow rate and the inlet and outlet temperature difference of the cooling water in the i-th section of the cooling wall in the target area of ​​the blast furnace and calculate the actual cooling degree control index X i , if X i <Xmin-i , then increase the cooling water flow rate and / or increase the inlet and outlet temperature difference of the cooling water; if X i >X max-i , then reduce the cooling water flow rate and / or reduce the inlet and outlet temperature difference of the cooling water; X min-i , X max-i They represent the minimum cooling degree control index and the maximum cooling degree control index of the i-th section cooling wall respectively.

[0020] Furthermore, the method also includes step 6, saving the maximum and minimum values ​​of the cooling wall heat load and the maximum and minimum values ​​of the cooling degree control index into a database.

[0021] Compared with the prior art, the present invention has the following beneficial effects: based on the collected data, a slag skin heat load relationship and a cooling index calculation formula are constructed, so that the calculation process of the cooling wall heat load data and the cooling degree control index is clear and accurate; actual data is brought into the calculation relationship and the cooling system is evaluated based on the specific data, the evaluation result is more reliable and convincing, and it is simple and easy to operate, highly practical and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of the calculation and evaluation method of blast furnace cooling system;

[0023] Figure 2 This is the fitting relationship diagram between blast furnace slag skin thickness and heat load. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] like Figure 1 As shown, the calculation and evaluation method of blast furnace cooling system includes:

[0026] Step 1: Collect target blast furnace data.

[0027] In this embodiment, taking the data of high heat load area (lower section of furnace body, furnace waist, furnace belly) as an example, the data of cooling wall slag thickness and cooling wall heat load within the preset time are collected, as shown in Table 1, and some blast furnace process technical parameters, including specific heat capacity of water, cooling wall area, number of cooling wall layers, distribution ratio of total heat loss of blast furnace between cooling wall and furnace shell, etc., as shown in Table 2. In this embodiment, the preset time is one week, and the preset time can also be adjusted according to actual conditions, as long as representative data can be collected.

[0028] Table 1 Cooling wall slag thickness and cooling wall heat load data

[0029] Serial number <![CDATA[Heat load (kW·m -2 ·s -1 )]]> Slag skin thickness (mm) 1 5.51 199.24 2 4.77 231.40 3 3.95 282.84 4 7.46 145.39 5 3.62 308.03 6 7.03 156.01 7 5.95 184.56 8 3.62 309.19 9 3.43 325.24 10 3.38 328.56 11 3.95 281.90 12 6.11 180.89 13 3.48 321.70 14 11.19 89.32 15 13.32 77.49 16 19.06 49.52 17 8.08 127.04 18 18.54 53.82 19 14.05 70.65

[0030] Table 2 Some blast furnace process parameters

[0031]

[0032]

[0033] Step 2: define the relationship between the slag skin thickness and the heat load in the target area of ​​the blast furnace and the relationship between the heat load and the cooling degree control index.

[0034] The heat load (q) data of different high-load areas and the corresponding slag skin thickness (s) data obtained in step 1 are read, and nonlinear regression analysis is performed to define the relationship between the slag skin thickness and the heat load of the cooling wall in the high-load area of ​​the target blast furnace. Based on this embodiment, the following relationship is obtained, and the correction determination coefficient (AdjustedRSquare) of the regression equation is required to be greater than 95%.

[0035] s=f(q)=a(1-e (-bq )) c (1)

[0036] Where: s represents the slag skin thickness, %; q is the cooling wall heat load, kW·m -2 ·s -1 ; a, b, c are constants.

[0037] Substituting the data in Table 1, the fitting graph can be calculated, such as Figure 2 As shown, the regression equation parameters are: a is 0.00281, b is 4.92298×10 -6 , c is -1.06156, the correction coefficient is above 99%, greater than 95%, which meets the requirements, and the fitting results are relatively accurate.

[0038] The product of the water flow rate L and the water temperature difference Δt is used as the cooling degree control index X. If the heat load q is directly fitted with the cooling degree control index X, the error is large. Therefore, this embodiment combines some blast furnace process technical parameters for fitting to obtain the cooling index calculation formula:

[0039]

[0040] Where: X is the cooling degree control index, t·h -1 ·℃; i is the number of each cooling wall of the blast furnace, generally a positive integer; c is the specific heat capacity of water, J / (kg·℃); F i is the heat dissipation area of ​​the i-th cooling wall, m 2 : ω is the heat distribution ratio, which is the distribution ratio of the total heat lost by the blast furnace between the cooling wall and the furnace shell; ni is the number of cooling wall layers in the i-th section, usually 1 or 2.

[0041] Step 3: Calculate the target blast furnace cooling wall heat load control value.

[0042] According to the actual demand for slag thickness in the target area of ​​the blast furnace, the slag thickness control range [s min ,s max ], generally 30 to 100 mm, the slag skin thickness control range is brought into the slag skin heat load relationship to calculate the target blast furnace cooling wall heat load control range [q min ,q max ], the specific calculation formula is as follows:

[0043]

[0044]

[0045] Correspondingly,

[0046]

[0047] X min-i , X max-i They respectively represent the minimum cooling control index and the maximum cooling control index of the i-th section cooling wall in the high load area of ​​the target blast furnace.

[0048] Substitute the data from step 2 and calculate q min =10.46kW·m -2 ·s -1 ,q max =28.11kW·m 2 ·s -1 , then the reasonable heat load control range of the cooling wall in the target area of ​​the blast furnace is 10.46≤q≤28.11.

[0049] Substituting the heat load control range and the data in Table 2 into the cooling index calculation formula, we can obtain: X min-9 =284.49t·h -1 ℃,X max-9 =764.53t·h -1 ·℃, then the reasonable cooling degree control range of the target blast furnace 9th cooling wall is 284.49≤X 9 ≤764.53;

[0050] X of the 10th cooling wall min-10 =300.97t·h -1 ℃,X max-10 =808.83t·h -1·℃, then the reasonable cooling degree control range of the target blast furnace 9th cooling wall is 300.97≤X 10 ≤808.83;

[0051] X of the 11th cooling wall min-11 =270.12t·h -1 ℃,X max-11 =725.91t·h -1 ·℃, then the reasonable cooling degree control range of the target blast furnace 9th cooling wall is 270.12≤X 11 ≤725.91.

[0052] Step 5: Determine the rationality of the cooling system for each cooling wall section in the target area of ​​the blast furnace.

[0053] The current water flow and water temperature difference of the cooling wall of the 9th to 11th sections of the target blast furnace are collected, as shown in Table 3.

[0054] Table 3 Real-time data collection of target blast furnace

[0055] Serial number Name and unit symbol Numeric 28 Water flow rate of the 9th cooling wall, t / h <![CDATA[L 9 ]]> 254.8 29 Water flow rate of the 10th cooling wall, t / h <![CDATA[L 9 ]]> 154.9 30 Water flow rate of cooling wall section 11, t / h <![CDATA[L 9 ]]> 154.9 31 Water temperature difference of the 9th cooling wall, ℃ <![CDATA[Δt 9 ]]> 1.51 32 Water temperature difference of the 10th cooling wall, ℃ <![CDATA[Δt 10 ]]> 1.80 33 Water temperature difference of the 11th cooling wall, ℃ <![CDATA[Δt 11 ]]> 1.90

[0056] Substituting Table 3 into the formula X=LΔt, the cooling index X of the current 9th to 11th cooling wall is calculated and compared with the reasonable control range of the cooling index:

[0057] 1) Cooling index X of the 9th cooling wall 9 =384.85t·h -1 ℃, found X 9 Satisfy 284.49≤X 9 ≤764.53, it is considered that the cooling system of this section of cooling wall is reasonable and does not need to be adjusted temporarily.

[0058] 2) Cooling index X of the 10th cooling wall 10 =278.82t·h -1 ℃, found X 10 Satisfy X 10 ≤300.97, it is considered that the cooling system of this section of cooling wall is unreasonable, indicating that the cooling degree is weak and there is a risk of thickening of the furnace wall. Adjustments should be made, starting with increasing the water flow and water temperature difference.

[0059] 3) Cooling index X of the 11th cooling wall 11 =294.31t·h -1 ℃, found X 11 Satisfy 270.12≤X 11 ≤725.91, it is considered that the cooling system of this section of cooling wall is reasonable and does not need to be adjusted temporarily.

[0060] If the cooling index of a certain cooling wall is X i>X max-i , indicating that the degree of cooling is too strong and the cooling wall is at risk of erosion. Adjustments should be made by reducing the water flow rate and water temperature difference.

[0061] Furthermore, the maximum and minimum values ​​of the cooling wall heat load and the maximum and minimum values ​​of the cooling degree control index can be saved in the database for subsequent use.

Claims

1. A method for calculating and evaluating a blast furnace cooling system, characterized in that: include: Step 1, collecting the cooling wall slag thickness s, cooling wall heat load data q, cooling water flow L and the inlet and outlet temperature difference Δt of the cooling water in the target area of ​​the blast furnace within a preset time; Step 2: Based on the cooling wall heat load data q obtained in step 1 and the corresponding slag skin thickness s, a slag skin heat load relationship is established: s=f(q); based on the cooling wall heat load data q, the cooling water flow rate L and the inlet and outlet temperature difference Δt of the cooling water, a cooling index calculation formula is established: X=y(q), where X is the cooling degree control index, and X=LΔt; Step 3: According to the actual demand for slag thickness in the target area of ​​the blast furnace, select the slag thickness control range [s min ,s max ]; Substitute the slag skin thickness control range into the slag skin heat load relationship to calculate the blast furnace target area cooling wall heat load control range [q min ,q max ]; Step 4: Substitute the cooling wall heat load control range into the cooling index calculation formula to calculate the cooling degree control index parameter range of the cooling wall in the target area [X min , X max ]; Step 5: Collect the real-time cooling water flow rate and the inlet and outlet temperature difference of the cooling water of the cooling wall in the target area of ​​the blast furnace and calculate the actual cooling degree control index. If the actual cooling degree control index exceeds the cooling degree control index parameter range, it is necessary to adjust the cooling water flow rate and / or the inlet and outlet temperature difference of the cooling water until the actual cooling degree control index is within the cooling degree control index parameter range.

2. The method for calculating and evaluating blast furnace cooling schedule according to claim 1, characterized in that: The step 2 uses nonlinear regression analysis to construct a slag skin heat load relationship.

3. The method for calculating and evaluating blast furnace cooling schedule according to claim 2, characterized in that: The correction coefficient of the regression equation when constructing the slag skin heat load relationship is greater than 95%.

4. The method for calculating and evaluating blast furnace cooling schedule according to claim 3, characterized in that: The heat load relationship of the slag skin is: s = f (q) = a (1-e (-bq )) c ; In the formula, s represents the slag skin thickness, q is the cooling wall heat load, and a, b, and c are constants.

5. The method for calculating and evaluating blast furnace cooling schedule according to claim 1, characterized in that: The step 1 also includes collecting the heat dissipation area F of the i-th cooling wall in the target area of ​​the blast furnace i , the distribution ratio of the total heat dissipated by the blast furnace between the cooling wall and the furnace shell ω, the number of cooling wall layers in the i-th section n i and the specific heat capacity of water, c; The step 2 is based on the cooling wall heat load data q, the cooling water flow rate L, the cooling water inlet and outlet temperature difference Δt, the heat dissipation area F of the i-th cooling wall i , the distribution ratio of the total heat lost by the blast furnace between the cooling wall and the furnace shell ω, the number of cooling wall layers in the i-th section n i And the specific heat capacity c of water to construct the cooling index calculation formula.

6. The method for calculating and evaluating blast furnace cooling schedule according to claim 5, characterized in that: The step 2 uses linear regression analysis to construct a cooling index calculation formula.

7. The method for calculating and evaluating blast furnace cooling schedule according to claim 6, characterized in that: The cooling index calculation formula is:

8. The method for calculating and evaluating blast furnace cooling schedule according to any one of claims 1 to 7, characterized in that: The step 5 is specifically as follows: Collect the real-time cooling water flow rate and the inlet and outlet temperature difference of the cooling water in the i-th section of the cooling wall in the target area of ​​the blast furnace and calculate the actual cooling degree control index X i , if X i <X min-i , then increase the cooling water flow rate and / or increase the inlet and outlet temperature difference of the cooling water; if X i >X max-i , then reduce the cooling water flow rate and / or reduce the inlet and outlet temperature difference of the cooling water; X min-i , X max-i They represent the minimum cooling degree control index and the maximum cooling degree control index of the i-th section cooling wall respectively.

9. The method for calculating and evaluating blast furnace cooling schedule according to claim 8, characterized in that: The method also includes step 6, saving the maximum and minimum values ​​of the cooling wall heat load and the maximum and minimum values ​​of the cooling degree control index into a database.

Images