Method for treating thickening of furnace wall of blast furnace

Abstract

The invention relates to the field of blast furnace operation of iron and steel enterprises, in particular to a method for treating blast furnace wall thickening. The method comprises the following steps: (1) judging the thickening condition according to the temperature of the wall body of the furnace body; and (2) material suspension is caused artificially. And (3) the air pressure is controlled to be less than or equal to 320kpa after material suspension, and the time is prolonged by 2-3 hours as much as possible. And (4) controlling the top temperature after suspending the material, cooling with water, controlling the gas temperature to be less than 300 DEG C, and ensuring that the inlet temperature of the dry dedusting cloth bag is normal. And (5) the soft water flow of the blast furnace is reduced to 4000 m < 3 > / h from 6000 m < 3 > / h, and the water flow of the cooling wall is kept to reach the normal 2 / 3 level. (6) selecting a heat system, wherein si is equal to 0.8-1.0%; and a slagging system is selected as follows: R2 is equal to 1.10-1.15 times. (7) prolonging the material suspension time for 2-3 hours, heating a thickened part by utilizing heat of concentrated coke, exhausting for material setting after sufficient heating, and pulling down furnace wall bonding materials by utilizing reverse drawing force in the process of pulling air for material setting; and if no suspended material exists, the furnace wall is scoured by utilizing high-temperature coal gas flow. The method has the characteristics of furnace condition stabilization, yield increase and consumption reduction.

Description

Technical Field

[0001] The present invention relates to the field of blast furnace operation in iron and steel enterprises, namely, a method for treating the thickening of the blast furnace wall Background Art

[0002] The inner profile of a modern smelting blast furnace is a typical five-section structure, which consists of five parts starting from the blast furnace top, namely the throat, the shaft, the bosh, the hearth and the tuyere zone. The furnace body is composed of a furnace shell, a cooling stave and refractories. Under normal circumstances, the blast furnace profile is divided into a designed profile, an operating profile and an ideal profile. During production, the inner profile of the blast furnace constantly changes. Generally, the change is slow and not noticed by iron-smelting workers. The reasons for the adhesion of the furnace wall are as follows: the upper part thickens due to improper treatment of the long-term edge duct, too light or too heavy edge gas, too much powder in the raw fuel, long time of stock line deficit, high upper temperature, frequent upper hanging of materials, etc.; the lower part thickens due to large fluctuations in furnace temperature and alkalinity, excessive cooling intensity, too low edge heat load, long-term abnormal furnace conditions, etc. Excessive long-term injection volume, insufficient heat compensation, incomplete combustion; long-term blocking of tuyeres, easy thickening in the tuyere zone and the upper part; long-term leakage of cooling equipment; high load of zinc and alkali metals, etc. The thickening of the modern blast furnace wall is mainly caused by alkali metals, potassium and sodium, which enter the blast furnace with iron-bearing burden, coke and coal. The alkali metals in the blast furnace participate in the reduction-oxidation and evaporation-condensation cycles, and play a catalytic role in the solution loss reaction (C + CO2 → 2CO); secondly, it intensifies the changes of coke and iron-bearing burden, resulting in poor permeability, which will affect the productivity of the blast furnace at a high production level; in addition, solid burden adheres to the furnace wall of the blast furnace shaft, erodes the furnace wall, and in extreme cases leads to hanging and slipping of materials, and thickening appears at the softening and melting position in the hearth / bosh area. Intuitively, it is manifested by an increase in hanging and slipping of materials in the blast furnace and a decline in indicators; on the other hand, the wall temperature in the bosh and the lower and middle parts of the blast furnace shaft drops by more than 20 °C compared with normal, and the control of the operating profile is unstable. When thickening occurs, the traditional method is: for the nodulation below the lower part of the shaft, washing burden can be added or the method of strongly developing the edge gas flow can be used to scour the nodulation on the furnace wall; the treatment method for the nodulation or thickening of the upper furnace wall of the blast furnace is to use the blasting method to blow up the adhesives on the furnace wall. Therefore, this method takes a long time, there are great safety hazards in using explosives, and the losses are serious. The treatment effect is not significant, and it is necessary to provide an effective method for treating the thickening of the furnace wall.

[0003] 2680m 3The blast furnace has a total of 15 cooling sections, and the positions of the cooling stave in each section are as follows: the 1st - 3rd sections of the hearth (including the iron notch area), the 4th section is the tuyere zone, the 5th - 7th sections are the bosh, the waist, and the lower part of the stack, the 8th - 10th sections are the middle - lower part of the stack, the 11th section is the middle part of the stack, and the 12th - 15th sections are the upper part of the stack. Generally speaking, the 8th cooling stave is the position of the slag - forming zone in the blast furnace. When the alkali load of the blast furnace exceeds the standard (≤3.5 kg / t, ≤0.15 kg / t zinc load), or the furnace condition is not smooth for a long time, the blast furnace is prone to thickening at this position, resulting in the non - smooth operation of the blast furnace and the decline of various economic indicators. Summary of the Invention

[0004] The object of the present invention is to provide a method for treating the thickening of the blast furnace wall to stabilize the furnace condition, increase production, and reduce consumption in view of the above - mentioned deficiencies.

[0005] The technical solution of the present invention is: a method for treating the thickening of the blast furnace wall, and its steps are as follows: (1) Judge the thickening situation according to the temperature of the furnace wall body, and the standard is that the wall body temperature is 15 - 20 °C lower than the normal value.

[0006] (2) During the normal production of the furnace condition, pre - add 210 tons of coke, reach the position of the 8th cooling stave in the lower part of the stack, reduce the proportion of the center coke 1 hour in advance, spread the coke charging flatly, C 9 2 8 2 7 2 6 2 5 2 2 2, change the ore system to O 9 2 8 2 7 2 6 2↓, promote the fluctuations of the burden distribution system, the tuyere blowing system, and the heat system, and artificially cause hanging of the charge.

[0007] (3) After the hanging of the charge, control the blast pressure ≤320 kpa and extend the time as long as possible for 2 - 3 hours.

[0008] (4) After the hanging of the charge, control the top temperature well, do a good job in spraying water for cooling, control the gas temperature less than 300 °C, and ensure the normal temperature at the inlet of the dry dust removal bag.

[0009] (5) Adjust the soft water flow rate of the blast furnace from 6000 m 3 / h to 4000 m 3 / h, and keep the water flow through the cooling stave at 2 / 3 of the normal level.

[0010] (6) Selection of the heat system: si = 0.8 - 1.0%; selection of the slag - making system: R2 = 1.10 - 1.15 times. si is the symbol of the silicon content in pig iron, representing the furnace temperature, which is a method of expressing chemical heat. R2 is the method of expressing the binary basicity of the slag, which is the binary basicity in the slag.

[0011] (7) The hanging material time is extended by 2 - 3 hours. Use the heat of the concentrated coke to heat the thickened part of the furnace wall. After sufficient heating, then carry out air release and stock settling, and strive to pull down the bonded materials on the furnace wall by using the reverse suction force during the process of pulling air and stock settling; if there is no hanging material, use the high-temperature coal gas flow to scour the furnace wall.

[0012] The advantages of the present invention are as follows: 1. The treatment time is short. The normal smelting cycle of the blast furnace is 4.5 hours, and 2 - 3 smelting cycles are required (see steps 2 and 7); the normal blast pressure is 380 - 390 kPa, the treatment loss is small, the time is short, the recovery is fast, it is safe and efficient, and the blast furnace production capacity reaches the normal level in 15 hours (see steps 3 and 4). 2. By concentrating the addition of coke, reducing the soft water flow rate, and using the high-temperature coal gas flow to scour, the treatment of the thickening of the blast furnace wall is realized. 3. On the basis of the traditional method for treating the thickening of the furnace wall, this method eliminates factors such as time-consuming, laborious, wasteful, and unsafe. Strive to pull down the bonded materials on the furnace wall by using the reverse suction force during the process of pulling air and stock settling; if there is no hanging material, use the high-temperature coal gas flow to scour the furnace wall. 4. When used during normal production, after the treatment of the thickening of the furnace wall is completed, it is easy to recover and promotes the improvement of indicators. 5. The treatment process of this method is relatively safe, efficient, and energy-saving, does not require blast furnace shutdown, and does not cause any damage to the refractories of the blast furnace body and furnace wall.

[0013] The embodiments of the present invention will be further described in detail below in conjunction with the examples. Specific embodiments

[0014] A method for treating the thickening of the blast furnace wall (taking a 2680 m 3 blast furnace volume as an example), the steps are as follows: 1. Judge the situation of the thickening of the furnace wall; the method for judging the thickening of the furnace wall is as follows: The furnace condition is difficult to operate, and there are often phenomena such as uneven feeding (slow feeding at the thickened part), caving, and hanging material; the change of the charging system cannot achieve the expected effect. At the lower part of the thickening, the edge often automatically becomes heavier and the center is too light. At the upper part of the thickening, the gas circumference is seriously uneven, and there is a phenomenon that the first point of the CO2 curve at the thickened part is higher than the second point. In severe cases, the second point is higher than the third point; the pressure-volume relationship is not adaptable, the strain capacity is very weak, and it does not accept the blast volume; the cooling water temperature difference and the furnace wall temperature at the thickened part decrease; the amount of gas ash blown out increases; the surface temperature distribution of the furnace shell is abnormal. The specific method is: Judge the lowest position and direction of the thickening of the furnace wall according to the temperature of the furnace wall thermocouple measurement points, the temperature of the blast furnace shell, and the heat flux intensity of the cooling stave. The thickening of the furnace wall will cause the furnace wall temperature to be lower and there is no change in temperature for a long time. The standard is that the wall body temperature is 15 - 20 °C lower than the normal value (60 °C). The standard range of the cooling stave temperature is 60 - 80 °C. Production practice shows that when the wall body temperature is at the level of 40 - 45 °C, thickening will occur in front of the furnace, the entire furnace volume becomes smaller, affecting the smoothness of the furnace condition and indicators. Therefore, it is stipulated that the wall body temperature is 15 - 20 °C lower than the normal value.

[0015] Specifically, it is mainly based on the temperature of the blast furnace wall, the temperature of the blast furnace shell, and the heat flux intensity of the cooling stave to comprehensively judge the thickness of the furnace wall buildup. The judgment method is as follows: A certain number of thermocouples are installed in the circumferential direction of the upper part of the blast furnace body. The thermocouple temperature is used to measure the temperature of the blast furnace wall. By comparing the historical data of these thermocouple temperatures, the thermocouple temperature at the position of the furnace wall buildup should be relatively low and rather stagnant. Based on this, the approximate position of the furnace wall buildup can be judged.

[0016] The position of the buildup can also be judged based on the temperature of the blast furnace shell. Find the low point of the historical data of the shell temperature, which is the position of the furnace wall buildup.

[0017] The position of the buildup is judged based on the heat flux intensity of the cooling stave. The position with a low heat flux intensity is the position of the buildup.

[0018] The calculation method of the heat flux intensity is as follows: Heat flux intensity = temperature difference of single cooling stave water × cooling water flow of single cooling stave × 4.18 × 3600 / area of single cooling stave.

[0019] Unit of heat flux intensity: kj / m 2 .h.

[0020] Temperature difference of cooling stave water: outlet water temperature of single cooling stave - inlet water temperature of single cooling stave, unit °C.

[0021] Unit of cooling water flow of single cooling stave: (kg / s).

[0022] 4.18 is the specific heat capacity of water.

[0023] 3600 is 3600 seconds per hour.

[0024] Unit of area of single cooling stave (m 2 ).

[0025] 2. When the furnace is in normal production, pre-add 210 tons of coke. When it reaches the position of the 8th cooling stave in the lower part of the furnace body (softening melting zone), reduce the proportion of center coke 1 hour in advance, spread the coke charging flat, C 9 2 8 2 7 2 6 2 5 2 2 2, change the ore preparation to O 9 2 8 2 7 2 62↓, which causes fluctuations in the burden charging system, the tuyere blowing system, and the heat system, artificially creating stock sticking. The 8th section of the cooling stave in the lower part of the furnace body is the root position of the BF cohesive zone. Adding 210 tons of coke just fills this position. In the burden charging system, the coke and ore are laid flat, which is conducive to blocking the gas passage, artificially causing stock sticking in the furnace condition, concentrating heat addition, and facilitating the melting of the bonding substances on the wall at this position.

[0026] 3. After stock sticking, control the blast pressure ≤ 320 kPa and extend the time as long as possible for 2 - 3 hours. When stock sticking occurs in the BF, a blast pressure of 320 kPa is the maximum safe blast pressure for the BF. A stock sticking time of 2 - 3 hours can more fully promote the melting of the bonding substances on the furnace wall.

[0027] 4. After stock sticking, control the top temperature well, carry out water spraying for cooling, control the gas temperature below 300 °C, and ensure the normal temperature at the inlet of the cloth bag. Under normal circumstances, the gas temperature entering the cloth bag box is controlled at (80 - 300) °C. If it is higher than 300 °C, it will burn out the cloth bag and cause equipment damage.

[0028] 5. Three soft water pumps of the BF are in operation, with a designed soft water flow rate of 6000 m 3 / h. When dealing with the thickening, stop one soft water pump, and the flow rate reaches 4000 m 3 / h, maintaining the water flow rate through the cooling staves at 2 / 3 of the normal level. The BF water cooling system adopts a combined soft water closed - loop circulation system. The water consumption of the cooling staves is 6000 m 3 / h, and it is adjusted down to 4000 m 3 / h, which is the minimum safe water consumption for the cooling staves, reducing the cooling intensity of the furnace body and the heat loss carried away by the cooling water.

[0029] 6. Selection of the heat system: si = 0.8 - 1.0%, where si is Symbol for the chemical heat of pig iron ; Selection of the slag - making system: R2 = 1.10 - 1.15 times, where R2 is Symbol for the binary basicity of slag . si is the symbol for the silicon content in pig iron, representing the furnace temperature, which is a way of expressing chemical heat. When the furnace temperature is in this range, it means that there is sufficient heat in this range, which is conducive to melting the bonding substances on the furnace wall; R2 is a way of expressing the binary basicity of the slag, which is the common simplified form of the binary basicity in the slag: CaO / SiO2 in BF production. When R2 = 1.10 - 1.15 times, the physical properties such as the viscosity and melting temperature of the slag are the best.

[0030] Control the top temperature during stock sticking < 350 °C, carry out water spraying for cooling, control the gas temperature below 300 °C, and ensure the temperature at the inlet of the cloth bag is 140 - 280 °C.

[0031] 7. Prolong the hanging stock time by 2 - 3 hours as much as possible. Use the heat of the concentrated coke to heat the thickened part of the furnace wall. After sufficient heating, carry out air release and stock settling (when normally blowing air, the blast furnace air release valve is fully closed, and stock settling is to manually open the air release valve). Try to pull down the adhesives on the furnace wall by using the reverse suction force during the process of pulling air and stock settling; if there is no hanging stock, use the high-temperature coal gas flow to scour the furnace wall. The treatment time is short, the loss is small, and the recovery is fast; pulling air and stock settling means artificially releasing the air volume entering the furnace. It's like there is something on the wind, and suddenly the wind disappears, and the things above have no support and fall down; the coal gas flow refers to the stable gas flow path formed in the furnace during the blast furnace smelting process when the air volume blown in from the tuyere. This gas flow searches for a path in the burden column structure in the furnace and finally reaches the furnace top, forming a stable coal gas flow. This method is to make it unstable, let the gas flow go along the edge, scour the furnace wall, make the adhesives on the furnace wall fall off, and the temperature of the furnace wall at this place rises and returns to the normal level of 60 - 80 °C.

[0032] The above description is only the specific implementation mode of the present invention, and various examples do not constitute a limitation to the essence of the present invention.

Claims

1. A method for treating the thickening of the blast furnace wall, characterized in that The steps are as follows: (1) Judge the thickening situation according to the temperature of the furnace body wall, with the standard that the wall temperature is 15 - 20°C lower than the normal value; (2)During normal furnace operation, pre-add 210 tons of coke until it reaches the position of the 8th cooling stave in the lower part of the furnace shaft. Reduce the proportion of center coke by 1 hour in advance, spread the coke evenly for charging, C 9 2 8 2 7 2 6 2 5 2 2 2, change the ore preparation to O 9 2 8 2 7 2 6 2↓, causing fluctuations in the burden distribution system, tuyere blowing system, and heat regime, artificially creating a hanging charge; (3) After the stock hanging, control the blast pressure ≤ 320 kPa and extend the time as much as possible for 2 - 3 hours; (4) After the stock hanging, control the top temperature well, do a good job in water spraying for cooling, control the gas temperature to be less than 300°C, and ensure the normal temperature at the inlet of the dry dedusting bag; (5)The flow rate of soft water in the blast furnace is reduced from 6000 m 3 / h to 4000 m 3 / h, and the water flow through the cooling stave is maintained at 2 / 3 of the normal level; (6) Selection of heat regime: si = 0.8 - 1.0%; Selection of slag-making regime: R2 = 1.10 - 1.15 times; (7) Extend the stock hanging time for 2 - 3 hours, use the heat of the concentrated coke to heat the thickened part, and then carry out blowing-down to sit the charge after sufficient heating. Try to pull down the furnace wall adhesives by the reverse suction force during the process of pulling the charge to sit; If there is no stock hanging, use the high-temperature gas flow to scour the furnace wall.