A method for preventing burn-out of converter dust collector bags under low iron consumption smelting conditions

Abstract

The present invention relates to the technical field of converter control in steel metallurgy, and specifically discloses a control method for preventing converter dust removal bags from burning under low iron consumption smelting conditions, comprising the following steps: 1) controlling the oxygen flow rate during blowing, and executing the lowering of the active smoke hood to the lower limit; 2) mixing a heat-supplementing and warming agent with other materials and adding them in batches; 3) controlling the oxygen flow rate during blowing according to the oxygen blowing time point; 4) automatically controlling the speed setting value of a primary fan according to converter production, and dividing it into three automatic control models according to the silicon content of molten iron entering the furnace; 5) setting the frequency of a secondary fan to 37 Hz, and automatically controlling the opening of a secondary dust removal damper in stages; 6) when the silicon content of molten iron is less than 0.05%, the silicon-low-carbon-oxygen reaction overlaps with the period of adding the warming agent in advance, and the coal gas recovery starts 180 seconds after the start value of the late recovery; the present invention is simple to operate, effectively suppresses large smoke and fire when the heat-supplementing agent is added, avoids the converter dust removal bags from burning, and ensures that the secondary emission detection value of the environmental dust removal meets the standard.

Description

Technical Field

[0001] This invention relates to the field of converter control technology in iron and steel metallurgy, specifically to a control method for preventing the burn-out of converter dust collector bags under low iron consumption smelting conditions. Background Technology

[0002] Many domestic long-process steel enterprises have chosen to adopt a low-cost solution with low iron consumption and high scrap steel ratio that can quickly achieve results. Under the low iron consumption mode, the converter solves the heat balance problem by adding carbonaceous and silicon heat supplements. However, the addition of carbonaceous heat supplements is often accompanied by short-term large smoke and fire, which can easily cause dust collector bags to burn and result in the immediate emission of particulate matter not meeting the standards, thus affecting the safety and environmental protection of enterprises.

[0003] For example, in a production mode with low iron consumption of 830-850 kg / t (high efficiency and low cost) and a high scrap steel ratio, the furnace mouth section is prone to producing large amounts of smoke and fire during the early stages of converter blowing due to the influence of economical scrap steel and heating agents. This has resulted in five instances of C7 dust collector bags burning, causing more than 60 hours of downtime and the replacement of more than 2,800 bags, resulting in significant economic losses. Therefore, there is an urgent need to design a control method to prevent converter dust collector bag burning under low iron consumption smelting conditions, in order to solve the problem of large amounts of smoke and fire easily damaging dust collector bags in the existing converter heat balance control. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a control method for preventing the burn-out of converter dust collector bags under low iron consumption smelting conditions.

[0005] The technical solution adopted by this invention to solve its technical problem is: a control method for preventing the burn-out of converter dust collector bags under low iron consumption smelting conditions, comprising the following steps:

[0006] 1) Control the oxygen flow rate and lower the movable fume hood to the lower limit;

[0007] 2) The heat-generating agent is mixed with other materials and added in batches;

[0008] 3) Control the oxygen flow rate according to the oxygen blowing time.

[0009] 4) The primary blower speed setting value is automatically controlled in stages according to the converter production. Based on the silicon content of the molten iron entering the furnace, there are three automatic control models.

[0010] 5) The secondary fan frequency is 37Hz, and the opening of the secondary dust removal damper is automatically controlled in stages.

[0011] 6) When the silicon content of molten iron is <0.05%, the silicon-low carbon-oxygen reaction occurs earlier and overlaps with the time when the heating agent is added, and the gas recovery begins 180 seconds after the initial value.

[0012] Specifically, the oxygen flow rate in step 1) is controlled at 28000-35000 Nm³. 3 / h, after the flame is full, lower the active smoke hood to the lower limit after 30 seconds.

[0013] Specifically, the other materials in step 2) include, but are not limited to, lime and magnesium materials, and the total amount of the heat-generating agent added in a single furnace after being mixed with other materials is less than 3500 kg.

[0014] Specifically, in step 3), the oxygen blowing starts at a rate of 400 Nm³ after 45 seconds of blowing. 3 At that time, the oxygen flow rate was controlled at 33000 Nm. 3 At a rate of / h, begin adding the heating agent. After addition is complete, the oxygen blowing rate is 850 Nm³. 3 At that time, the oxygen flow rate was controlled at 42000 Nm. 3 / h, oxygen blowing rate is 1000 Nm 3 Oxygen flow rate controlled at 48000 Nm 3 / h-50000Nm 3 / h, complete the remaining slag-forming material.

[0015] Specifically, in step 4), when the silicon content of molten iron is controlled at 0.01% ≤ molten iron silicon ≤ 0.10%, it is automatic control model one, and the fan speed is controlled at 1210rpm-1280rpm during the blowing stage.

[0016] When the silicon content of molten iron is controlled at 0.11% ≤ molten iron silicon ≤ 0.30%, it is automatic control model two, and the fan speed is controlled at 1230rpm-1300rpm during the blowing stage;

[0017] When the silicon content of molten iron is controlled at ≥0.31%, it is automatic control model three, and the fan speed is controlled at 1250rpm-1360rpm during the blowing stage;

[0018] Before loading, the fan speed is controlled at 1210rpm-1250rpm.

[0019] Specifically, the secondary dust removal damper in step 5) includes a left valve in front of the furnace, a right valve in front of the furnace, and a valve behind the furnace. The opening degree of the left valve in front of the furnace, the right valve in front of the furnace, and the valve behind the furnace is automatically controlled according to the production stage.

[0020] The present invention has the following beneficial effects:

[0021] This invention presents a control method for preventing the burning of converter dust collector bags under low iron consumption smelting conditions.

[0022] (1) Simple operation, effectively suppresses large smoke and fire when adding heat agent, avoids burnt converter dust collector bags, and ensures that the secondary emission detection value of environmental dust removal meets the standard.

[0023] (2) Reduce material costs. Due to the shutdown and replacement of the dust collector bags caused by burning, the cost of dust collector bags can be reduced by about RMB 400,000. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be described in further detail below, clearly and completely. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] A method for preventing burn-out of converter dust collector bags under low iron consumption smelting conditions includes the following steps:

[0027] (1) Add the heat-generating agent mixed with lime together, with an addition amount of <3500kg;

[0028] (2) After blowing for 45 seconds, the oxygen blowing volume is 400 Nm³. 3 At that time, the oxygen flow rate was controlled at 33000 Nm. 3 At a rate of / h, begin adding the heating agent. After addition is complete, the oxygen blowing rate is 850 Nm³. 3 At that time, the oxygen flow rate was controlled at 40000 Nm. 3 / h, oxygen blowing rate is 1000 Nm 3 Oxygen flow rate controlled at 48000 Nm 3 / h-50000Nm 3 / h, complete the addition of the remaining slag-forming materials; the specific addition time and amount are shown in Table 1:

[0029] Table 1 Comparison of the amount of heating agent and other materials added

[0030]

[0031] (3) The primary blower speed setting value is automatically controlled in stages according to the converter production. Based on the silicon content of the molten iron entering the furnace, there are three automatic control models. The speed is controlled at 1210rpm-1250rpm before charging. The specific control stages and modes of the blower speed are shown in Table 2 below:

[0032] Table 2 Fan Speed ​​under Three Automatic Control Models

[0033]

[0034] (4) The frequency of the secondary air fan is 37Hz. The opening of the secondary dust removal damper is automatically controlled in stages according to the converter production. The secondary dust removal damper includes the left valve in front of the furnace, the right valve in front of the furnace, and the valve in front of the furnace. The opening of the left valve in front of the furnace, the right valve in front of the furnace, and the valve in front of the furnace are automatically controlled according to the production stage, as shown in Table 3.

[0035] Table 3 Valve Execution Status under Automatic Control of Secondary Dust Removal Damperes

[0036]

[0037] (5) Under low iron consumption of 830kg / t-850kg / t, the silicon content of molten iron is less than 0.05%, and the gas recovery starts from 180s.

[0038] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0039] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for controlling the burning of converter dust collector bags under low iron consumption smelting conditions, characterized in that, The following steps are involved: 1) Control the oxygen flow rate at 28,000-35,000 Nm³ / h. After the flame is full, lower the movable smoke hood to the lower limit after 30 seconds. 2) The heat-generating agent is mixed with the slag-forming materials and added in batches. The slag-forming materials include, but are not limited to, lime and magnesium materials. The total amount of heat-generating agent and slag-forming materials added at the same time in a single furnace is <3500 kg. 3) Control the oxygen flow rate according to the oxygen blowing time; 4) The set value of the primary blower speed is automatically controlled in stages according to the converter production. Based on the silicon content of the molten iron entering the furnace, there are three automatic control models. When the silicon content of the molten iron is controlled at 0.01%≤molten iron silicon≤0.10%, it is automatic control model one. During the blowing stage, the blower speed is controlled at 1210rpm-1280rpm. When the silicon content of molten iron is controlled at 0.11%≤molten iron silicon≤0.30%, it is automatic control model two, and the fan speed is controlled at 1230rpm-1300rpm during the blowing stage; When the silicon content of molten iron is controlled at ≥0.31%, it is automatic control model three, and the fan speed is controlled at 1250rpm-1360rpm during the blowing stage; Before loading, the fan speed is controlled at 1210rpm-1250rpm; 5) The secondary fan frequency is 37Hz, and the opening of the secondary dust removal damper is automatically controlled in stages; 6) When the silicon content of molten iron is <0.05%, the carbon-oxygen reaction occurs earlier and overlaps with the time when the heat-generating agent is added. The gas begins to be recovered 180 seconds after reaching the initial value.

2. The control method for preventing burn-out of converter dust collector bags under low iron consumption smelting conditions according to claim 1, characterized in that, In step 3), the starting point of the blowing process is determined by the timing of the oxygen blowing. 45 seconds after the blowing begins, when the oxygen volume is 400 Nm³ and the oxygen flow rate is controlled at 33000 Nm³ / h, the supplementary heating agent is added. After the addition is complete, when the oxygen volume is 850 Nm³, the oxygen flow rate is controlled at 42000 Nm³ / h. When the oxygen volume is 1000 Nm³, the oxygen flow rate is controlled at 48000 Nm³ / h-50000 Nm³ / h, thus completing the addition of the remaining slag-forming materials.

3. The control method for preventing converter dust collector bag burnout under low iron consumption smelting conditions according to claim 1, characterized in that, The secondary dust removal damper in step 5) includes a left valve in front of the furnace, a right valve in front of the furnace, and a valve behind the furnace. The opening degree of the left valve in front of the furnace, the right valve in front of the furnace, and the valve behind the furnace is automatically controlled according to the production stage.

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