Calculation Method for Water Leakage in the Blast Furnace Closed-Circulation System

Abstract

The present invention discloses a calculation method for the water leakage amount of a blast furnace closed-loop circulation system, belonging to the technical field of blast furnace smelting. This method uses a specific calculation formula to calculate the water leakage amount in the furnace per unit time, and adjusts the coke amount of the blast furnace according to the water leakage amount to ensure the stable operation of the blast furnace within a certain period.

Description

Technical Field

[0001] The present invention relates to the stable and smooth implementation of blast furnaces, belonging to the technical field of blast furnace smelting, and specifically relates to a calculation method for the water leakage amount of a blast furnace closed-loop circulation system. Background Art

[0002] After a blast furnace has been in production for a certain number of years, due to the aging of cooling equipment, especially the wear of blast furnace cooling stave, a large number of cooling straight pipes are damaged and leak a large amount of water into the furnace. Especially in blast furnaces using a closed-loop circulation system, once the cooling equipment leaks water into the blast furnace, a large amount of heat in the blast furnace will be lost. In the light case, it will cause abnormal furnace conditions, and in the severe case, it will cause the freezing of the hearth. Generally, blast furnace operators adopt the method of increasing the heat supply of the blast furnace to stabilize the furnace conditions, and then deal with the leaking equipment according to the water leakage situation; the increased heat requires a quantitative standard. If too much heat is increased, it will cause the furnace to be too hot, affecting the smooth operation of the blast furnace and energy consumption indicators. If the increased heat is insufficient, it will cause the furnace to be cold or even the hearth to freeze. Therefore, calculating the specific water leakage amount of the blast furnace closed-loop circulation system is a technical problem that needs to be solved currently. Summary of the Invention

[0003] To solve the above technical problems, the present invention discloses a calculation method for the water leakage amount of a blast furnace closed-loop circulation system. This calculation method can calculate the specific water leakage amount and adjust the coke amount according to the water leakage amount, thereby ensuring the stable operation of the blast furnace within a certain period.

[0004] To achieve the above technical purpose, the present invention discloses a calculation method for the water leakage amount of a blast furnace closed-loop circulation system. Once it is found that the water replenishment cycle of the blast furnace closed-loop circulation system is shortened, it is determined that there is water leakage. The specific troubleshooting and water leakage amount calculation process is as follows:

[0005] 1) First, check whether all pipelines and / or heat exchangers and / or pump sets of the soft water closed-loop circulation leak water. If there is water leakage, eliminate the corresponding hidden dangers. If it is observed again that the water replenishment cycle of the blast furnace closed-loop circulation system is shortened or all pipelines, heat exchangers, and pump sets of the soft water closed-loop circulation do not leak water, it is determined that the cooling equipment of the blast furnace closed-loop circulation system leaks water into the furnace;

[0006] 2) The water leakage amount V per unit time of the blast furnace closed-loop circulation system 漏 satisfies the following mathematical relationship:

[0007] V 漏 = V 实 * 60 / ΔT;

[0008] V 漏 : The water leakage amount V per unit time 漏 , with the unit of m 3 / h;

[0009] V 实: The actual amount of water leakage in the furnace within the change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of m 3 ;

[0010] ΔT: The change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of min.

[0011] Furthermore, in the said step 2), V 实 satisfies the following mathematical relation:

[0012] V 实 = ΔV 总 - ΔV t -(V 耗 *ΔT) / 60;

[0013] ΔV 总 : The reduction amount of the system water volume within the change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of m 3 ;

[0014] ΔV t : The volume change amount caused by the water temperature change within the change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of m 3 ;

[0015] V 耗 : The water consumption per unit time when the blast furnace is stable, with the unit of m 3 / h;

[0016] ΔT: The change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of min.

[0017] Furthermore, in the said step 2), ΔV 总 satisfies the following mathematical relation:

[0018] ΔV 总 =(h 1 -h 2 )*S;

[0019] h 1 : The height of the expansion tank liquid level corresponding to the start end of the change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of m;

[0020] h 2 : The height of the expansion tank liquid level corresponding to the end end of the change period ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of m;

[0021] S: The cross-sectional area of the expansion tank, with the unit of m 2 .

[0022] Furthermore, in the said step 2), ΔV t satisfies the following mathematical relation:

[0023] ΔV t = m 总 / ρ 1 - m 总 / ρ 2 ;

[0024] m 总 : The total mass of water in the closed - loop system, unit: kg; and m 总 satisfies the following mathematical relation:

[0025] m 总 = V 原 *ρ 原 ;

[0026] V 原 : The water holding capacity of the closed - loop system, unit: m 3 ;

[0027] ρ 原 : Water density, unit: t / m 3 , where different atmospheric temperatures correspond to different water densities;

[0028] ρ 1 : The water density corresponding to the start of the change period ΔT of the expansion tank liquid level after the make - up water period is shortened is ρ at the outlet water temperature t 1 , and the water density is ρ 1 , with the water density unit being t / m 3 ;

[0029] ρ 2 : The water density corresponding to the end of the change period ΔT of the expansion tank liquid level after the make - up water period is shortened is ρ at the outlet water temperature t 2 ,and the water density is ρ 2 , with the water density unit being t / m 3 .

[0030] Furthermore, in step 2), V 耗 satisfies the following mathematical relation:

[0031] V 耗 = V 补 / t 原补 ;

[0032] V 补 : The one - time make - up water volume of the expansion tank of the closed - loop system, unit: m 3 ; and V 补 satisfies the following mathematical relation:

[0033] V 补 =(H 高 - H 低 )*S;

[0034] H 高: High water level position of the expansion tank, unit: m;

[0035] H 低 : Low water level position of the expansion tank, unit: m;

[0036] S: Cross-sectional area of the expansion tank, unit: m 2 ;

[0037] t 原补 : Water replenishment cycle during the stable period of the blast furnace condition; unit: h.

[0038] Furthermore, the cross-sectional area S of the expansion tank satisfies the following mathematical relationship:

[0039] S = πd 2 / 4;

[0040] d: Diameter of the expansion tank; unit: m.

[0041] Beneficial effects:

[0042] The present invention can calculate the specific water leakage amount of the blast furnace closed-loop circulation system through corresponding specific calculation formulas, and can adjust the coke amount of the blast furnace according to the water leakage amount, thereby ensuring the stable operation of the blast furnace within a certain period. Brief description of the drawings

[0043] Figure 1 It is a schematic structural diagram of the blast furnace closed-loop circulation system of the present invention. Among them, Figure 1 The numbers of each component are as follows:

[0044] Expansion tank 1, high liquid level point 2 of the expansion tank, liquid level gauge 3, low liquid level point 4 of the expansion tank, cooling device 5, circulating return water temperature measurement point 6, degassing tank 7, pump group 8. Specific implementation manners

[0045] Water leakage in the blast furnace will cause abnormal furnace conditions. In order not to affect the blast furnace temperature and ensure the smooth operation of the blast furnace, the present invention provides a calculation method for the water leakage amount of the blast furnace closed-loop circulation system.

[0046] Among them, the blast furnace closed-loop circulation system is as Figure 1 shown. The blast furnace body is connected to the pump group 8 and the cooling device 5. The cooling device of the present invention is preferably a heat exchanger, and the pump group of the present invention includes a circulating return water pump. At the same time, a circulating return water temperature measurement point 6 is also provided on the blast furnace body;

[0047] An expansion tank 1 is provided at the top of the blast furnace body. A liquid level gauge 3 is also provided on the expansion tank 1, and the liquid level gauge 3 can be used to display the high liquid level point 2 and the low liquid level point 4 of the expansion tank. In addition, the expansion tank 1 is also connected to the degassing tank 7. Among them, when the blast furnace closed-loop circulation system leaks, the liquid level of the expansion tank 1 drops, and the circulating return water pump quickly replenishes water. The interval between two water replenishments is called the water replenishment cycle.

[0048] Specifically, once it is found that the water replenishment cycle of the blast furnace closed-loop system is shortened, it is determined that there is a leak. The specific troubleshooting and calculation process of the leakage amount are as follows:

[0049] 1) First, check whether all pipelines, heat exchangers, and / or pump sets in the soft water closed-loop circulation leak. If there is a leak, eliminate the hidden danger. If it is observed again that the water replenishment cycle of the blast furnace closed-loop system is shortened or all pipelines, heat exchangers, and pump sets in the soft water closed-loop circulation do not leak, it is determined that the cooling equipment leaks into the furnace;

[0050] 2) The primary water replenishment volume V of the expansion tank in the closed-loop system 补 satisfies the following mathematical relationship:

[0051] V 补 =(H 高 -H 低 )*S; S = πd 2 / 4;

[0052] V 补 : The primary water replenishment volume, unit is m 3 ;

[0053] H 高 : The high liquid level of the expansion tank, unit is m;

[0054] H 低 : The low liquid level of the expansion tank, unit is m;

[0055] S: The cross-sectional area of the expansion tank, unit is m 2 ;

[0056] d: The diameter of the expansion tank; unit is m;

[0057] Among them, H 高 , H 低 and d can all be obtained from the design drawings of the blast furnace;

[0058] 3) The total mass of water in the closed-loop system satisfies the following mathematical relationship:

[0059] m 总 =V 原 *ρ 原 ;

[0060] m 总 : The total mass of water in the closed-loop system, unit is kg;

[0061] V 原 : The water holding capacity of the closed-loop system, unit is m 3 ; This value is also obtained from the design drawings of the blast furnace;

[0062] ρ原 : Water density, unit: g / cm 3 , where different atmospheric temperatures correspond to different water densities;

[0063] Among them, assuming the atmospheric temperature is t 原 , the corresponding water density ρ can be obtained by referring to Table 1 原 ;

[0064] Table 1: Density comparison table of water at different temperatures

[0065]

[0066]

[0067] 4) Water consumption V per unit time in the closed-loop system 耗 satisfies the following mathematical relationship: V 耗 = V 补 / t 原补 ;

[0068] V 耗 : Water consumption per unit time in the closed-loop system, unit: m 3 / h;

[0069] t 原补 : Make-up water cycle during the stable period of the blast furnace condition; unit: h;

[0070] 4) Calculation of the water leakage in the closed-loop system:

[0071] 4.1) The amount of water reduction ΔV in the closed-loop system within a certain calculation period ΔT after the make-up water cycle is shortened 总 satisfies the following mathematical relationship:

[0072] ΔV 总 =(h 1 -h 2 )*S;

[0073] The volume change dV caused by the water temperature change within the calculation period ΔT t That is, ΔV t satisfies the following mathematical relationship:

[0074] ΔV t = m 总 / ρ1 - m 总 / ρ2

[0075] The outlet water temperature at the start of the calculation period ΔT in the system is t 1 , and the corresponding water density is ρ 1 , and the liquid level height of the expansion tank at this time is h 1 ;

[0076] At the end of the calculation period ΔT, the outlet water temperature in the system is t 2 , and the corresponding water density is ρ 2 . At this time, the liquid level height of the expansion tank is h 2 ; among them, ρ 1和 ρ 2 can refer to Table 1 above. If it cannot be consulted, use the formula: ρ = -0.0037t 2 -0.0617t + 1000.7 is calculated. t is the water temperature, and ρ is the water density corresponding to this water temperature. This formula is a function obtained by using the regression curve of density and water temperature.

[0077] ΔV 总 : The reduction in the system water volume within the expansion tank liquid level change period ΔT after the makeup water cycle becomes shorter, with the unit of m 3 ;

[0078] 4.2) The actual leakage volume V in the furnace within the expansion tank liquid level change period ΔT after the makeup water cycle becomes shorter 实 satisfies the following mathematical relationship:

[0079] V 实 = ΔV 总 - ΔV t - V 耗 * ΔT / 60;

[0080] ΔV 总 : The reduction in the system water volume within the expansion tank liquid level change period ΔT after the makeup water cycle becomes shorter, with the unit of m 3 ;

[0081] ΔV t : The volume change caused by the water temperature change within the expansion tank liquid level change period ΔT after the makeup water cycle becomes shorter, with the unit of m 3 ;

[0082] V 耗 : The water consumption per unit time when the blast furnace is stable, with the unit of m 3 / h;

[0083] The water leakage volume V per unit time in the blast furnace closed-loop circulation system 漏 satisfies the following mathematical relationship:

[0084] V 漏 = V 实 * 60 / ΔT;

[0085] V 漏 : The water leakage volume V per unit time 漏 , with the unit of m 3 / h;

[0086] V 实: The actual amount of water leakage in the furnace within the change cycle ΔT of the expansion tank liquid level after the water replenishment cycle becomes shorter, with the unit of m 3 ;

[0087] ΔT: The change cycle ΔT of the expansion tank liquid level after the water replenishment cycle becomes shorter, with the unit of min.

[0088] To better explain the present invention, the following is a detailed description in conjunction with specific embodiments

[0089] Embodiment 1

[0090] The interval between two water replenishments of a certain blast furnace within a certain period of time is 15.63 h.

[0091] (1) According to the design drawings, the diameter of the expansion tank of this blast furnace is 2.5 m, the high liquid level of the expansion tank is 3.6 m, and the low liquid level of the expansion tank is 2.4 m;

[0092] Then the primary water replenishment volume V of the expansion tank in the closed circulation system 补 satisfies the following mathematical relationship:

[0093] V 补 =(H 高 -H 低 )*S=(3.6 - 2.4)*1.25*1.25*3.14159 = 1.2*4.9087 = 5.89 m 3 ;

[0094] (2) According to the original design drawings, the water holding capacity of the system of this blast furnace is calculated to be 1830 m 3 , and the current furnace condition of this blast furnace is stable. Taking the water temperature of 36 °C as the calculation benchmark, the density of water can be found to be: 0.9936883 t / m 3 ;

[0095] Then the total mass m of water in the closed circulation system 总 =V 原 *ρ 原 =1830*0.9936883 = 1818.449589 t.

[0096] (3) Observing that the on-site water replenishment cycle t 原补 is 15.63 h, then the water consumption per unit time V 耗 in the closed circulation system =V 补 / t original replenishment = 5.89 / 15.63 = 0.3768 m 3 / h.

[0097] (4) After the water replenishment cycle becomes shorter, the change cycle ΔT of the expansion tank liquid level is selected. The starting point is 10:24 on March 2, 2022, with the liquid level being 3.208 m and the temperature being 38.8 °C at this time. The end point is 11:28 on March 2, 2022, with the liquid level being 2.978 m and the temperature being 38.2 °C at this time.

[0098] And when the water temperature is 38.8 °C, the density of water is 0.9926735 t / m 3 ;

[0099] When the water temperature is 38.2 °C, the density of water is 0.9928960 t / m 3 ;

[0100] Then ΔV 总 =(h 1 -h 2 )*S=(3.208 - 2.978)*4.9087 = 1.129 m 3

[0101] ΔV t =m 总 / ρ 1 -m 总 / ρ 2 =1818.449589 / 0.9926735 - 1818.449589 / 0.9928960 = 1831.8708 - 1831.4603 = 0.4105 m 3 ;

[0102] Then the actual amount of water leakage in the furnace V within the change cycle ΔT of the expansion tank liquid level after the water replenishment cycle becomes shorter 实 V 实 =ΔV 总 -ΔV t -V 耗* ΔT / 60 = 1.129 - 0.4105 - 0.3768*64 / 60 = 0.31658 m 3.

[0103] The water leakage rate per unit time of the blast furnace closed - loop circulation system 漏 =V 实 *60 / ΔT = 0.31658*60 / 64 = 0.2968 m 3 / h.

[0104] Test Example 1

[0105] According to the water leakage rate per unit time of the blast furnace closed - loop circulation system calculated in the above Example 1, further adjust the amount of coke in the blast furnace to ensure the stable operation of the blast furnace within a certain period. The specific adjustment strategy is as follows:

[0106] To ensure sufficient furnace temperature in the blast furnace, especially in the case of water leakage, the furnace temperature should be maintained at the upper limit. First, it is defaulted that the water leakage occurs in the lower part of the blast furnace shaft.

[0107] The average blast volume of the blast furnace is 5700 m 3 / min. The water leakage can be regarded as an increase in blast humidity.

[0108] The hourly increase in blast humidity is: 0.2968 m 3 ×1000000 g / m 3 ÷60 min÷5700 m 3 / min = 0.867 g / m 3 ≈1 g / m 3 ;

[0109] (In the later stage of the furnace campaign, the cooling equipment is frequently damaged. To maintain sufficient furnace temperature and prevent accidents such as pipeline blockage and material slipping caused by water leakage, the actual measured value is evaluated according to the upper limit.);

[0110] For every 1 g / m 3 increase in moisture content, the coke ratio increases by 1 kg / tFe (each blast furnace has different measurement methods);

[0111] The ore batch weight of the blast furnace at this time is 90 t, the coke batch weight is 18.8 t, and the comprehensive iron content of a batch of ore is 59%;

[0112] Coke ratio = 18.8 t÷90 t÷59% = 354 kg / tFe;

[0113] After water leakage, the coke ratio increases by 1 kg / tFe. To maintain the existing furnace temperature, the coke ratio is 355 kg / tFe;

[0114] Back-calculated coke batch weight = 355 kg / tFe×59%×90 t = 18.85 t;

[0115] Considering that water leakage will induce pipeline problems resulting in a decrease in gas utilization rate and a further drop in furnace temperature, the coke batch weight is adjusted to 18.9 t, with an increase in coke amount per batch of 100 kg;

[0116] Note: According to the production situation of WISCO's blast furnaces in recent years, this water leakage level is relatively light. In the later stage of the furnace campaign, when the water leakage is severe, the water replenishment cycle is only 45 min, and the amount of coke to be supplemented is also relatively large.

[0117] The above embodiments are only the best examples and are not intended to limit the implementation modes of the present invention. In addition to the above embodiments, the present invention has other implementation modes. All technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A calculation method for the water leakage amount of a blast furnace closed-loop circulation system, characterized in that: Once it is found that the water replenishment cycle of the blast furnace closed-loop circulation system is shortened, it is determined that there is water leakage. The specific troubleshooting and calculation process of the water leakage amount is as follows: 1) First, check whether all pipelines and / or heat exchangers and / or pump sets of the soft water closed-loop circulation are leaking. If there is leakage, eliminate the corresponding hidden dangers. If it is observed again that the water replenishment cycle of the blast furnace closed-loop circulation system is shortened or all pipelines, heat exchangers and pump sets of the soft water closed-loop circulation are not leaking, it is determined that the cooling equipment of the blast furnace closed-loop circulation system leaks water into the furnace; 2) Water leakage volume V per unit time of the blast furnace closed-loop circulation system 漏 Satisfies the following mathematical relationship: V 漏 = V 实 * 60 / ΔT; V 漏 : Water leakage volume V per unit time 漏 , with the unit of m 3 / h; V 实 : The actual amount of water leakage in the furnace within the liquid level change period ΔT of the expansion tank after the water replenishment cycle is shortened, with the unit of m 3 ; ΔT: The change cycle ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, unit: min; In step 2), V 实 satisfies the following mathematical relationship: V 实 = ΔV 总 -ΔV t -(V 耗 *ΔT) / 60; ΔV 总 : The reduction in the system water volume within the change cycle ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, with the unit of m 3 ; ΔV t : The volume change caused by the water temperature change within the liquid level change period ΔT of the expansion tank after the water replenishment cycle is shortened, with the unit of m 3 ; V 耗 : Water consumption per unit time when the blast furnace is stable, unit: m 3 / h; ΔT: The change cycle ΔT of the expansion tank liquid level after the water replenishment cycle is shortened, unit: min; In step 2), ΔV 总 satisfies the following mathematical relation: ΔV 总 =(h 1 -h 2 )*S; h 1 : The liquid level height of the expansion tank corresponding to the start end of the change period ΔT of the liquid level of the expansion tank after the water replenishment period is shortened, with the unit of m; h 2 : the height of the expansion tank liquid level corresponding to the end of the change period ΔT of the expansion tank liquid level after the water replenishment period is shortened, with the unit of m; S: Cross-sectional area of the expansion tank, unit: m 2 ; In step 2), ΔV t satisfies the following mathematical relation: ΔV t = m 总 / ρ 1 - m 总 / ρ 2 ; m 总 : The total mass of water in the closed-loop system, in kg; and m 总 satisfies the following mathematical relationship: m 总 = V 原 * ρ 原 ; V 原 : The water inventory of the closed-loop system, unit: m 3 ; ρ 原 : Water density, unit: t / m 3 , where different atmospheric temperatures correspond to different water densities; ρ 1 : The outlet water temperature corresponding to the start end of the expansion tank liquid level change period ΔT after the water replenishment cycle is shortened is t 1 , the water density is ρ 1 , the unit of water density is t / m 3 ; ρ 2 : The outlet water temperature corresponding to the end of the expansion tank liquid level change period ΔT after the water replenishment cycle is shortened is t 2 , the water density is ρ 2 , the unit of water density is t / m 3 .

2. The calculation method for the water leakage amount of the blast furnace closed-loop circulation system according to claim 1, characterized in that: In step 2), V 耗 satisfies the following mathematical relationship: V 耗 = V 补 / t 原补 ; V 补 : The primary make-up water volume of the expansion tank in the closed-loop system, with the unit of m 3 ; and V 补 satisfies the following mathematical relation: V 补 = (H 高 - H 低 ) * S; H 高 : High water level position of the expansion tank, unit: m; H 低 : Low water level position of the expansion tank, unit: m; S: Cross-sectional area of the expansion tank, unit: m 2 ; t 原补 : The water replenishment cycle during the stable BF condition period; unit: h.

3. The calculation method for the water leakage amount of the blast furnace closed-loop circulation system according to claim 1 or 2, characterized in that: The cross-sectional area S of the expansion tank satisfies the following mathematical relationship: S = πd 2 / 4; d: The diameter of the expansion tank; unit: m.

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