Method for controlling fuel ratio before damping down of iron-making blast furnace

Abstract

The invention discloses a fuel ratio control method before damping down of an iron-making blast furnace, and belongs to the field of blast furnace operation control. The method comprises the steps that the furnace temperature before damping down is increased by controlling the ore reduction rate of damping down materials under a tuyere, the standard fuel ratio FR is calculated, the volume Vi of a batch of materials is calculated, the standard material speed S < standard > is calculated, the accumulated fuel ratio FR < rest > is calculated, and the hour fuel ratio FRh is adjusted according to the difference between the accumulated fuel ratio FR < rest > and the standard fuel ratio. The hourly fuel ratio level is ensured by controlling the material speed Si of each batch of materials, and the reasonable level of the material speed and the accumulated fuel ratio is ensured by controlling the hourly fuel ratio. By establishing a standardized fuel ratio calculation and control process, the problem that the fuel ratio control depends on personal experience and is large in deviation before damping down of the blast furnace is effectively solved. According to the method, furnace temperature trend judgment and balance in the damping-down material loading process can be accurately guided, the accuracy and stability of fuel ratio control are remarkably improved, and uncertain factors caused by operation habit differences are reduced.

Description

Technical Field

[0001] This invention relates to blast furnace operation control, and more particularly to a method for controlling the fuel ratio before shutting down an ironmaking blast furnace. Background Technology

[0002] In blast furnace production, controlling the appropriate fuel ratio is crucial for ensuring reasonable furnace temperature and maintaining stable and smooth furnace operation; it is both a key focus and a challenge in blast furnace operation. Controlling the fuel ratio before a blast furnace shutdown is even more difficult, as both excessively high and low fuel ratios can affect whether the blast furnace can be shut down normally. Due to the influence of shutdown materials, traditional calculation methods often result in a high fuel ratio before shutdown, rendering it largely meaningless. Foremen typically rely on their operational experience to make comprehensive judgments based on changes in furnace conditions and temperature trends. However, individual operating habits vary, leading to significant deviations in the final fuel ratio, which is an unstable factor affecting smooth furnace operation and the timely shutdown.

[0003] In response to the problem of large deviations in fuel ratio levels and the lack of control standards before blast furnace shutdown, there is an urgent need in the field of blast furnace operation and control technology for a fuel ratio control method that can accurately guide the judgment and balance of furnace temperature trends before shutdown. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for accurately controlling the fuel ratio level during the charging of blast furnace rest materials before shutdown, applicable to blast furnaces of various furnace caps, to ensure normal furnace temperature and smooth charging of rest materials before shutdown.

[0005] Technical solution: A method for controlling the fuel ratio before shutting down an ironmaking blast furnace, comprising the following steps:

[0006] S1. The furnace temperature before shutdown is increased by controlling the ore reduction rate of the shutdown material under the tuyeres. When the furnace temperature is normal or sufficient before the shutdown material is charged, the ore reduction rate of the shutdown material under the tuyeres is calculated as 15 kg / t higher than the coke ratio during normal production; when the furnace temperature is lower than the normal production temperature before the shutdown material is charged, the ore reduction rate of the shutdown material under the tuyeres is calculated as (15 + 0.5 × temperature difference) kg / t higher than the coke ratio during normal production.

[0007] S2. Calculate the standard fuel ratio FR. The standard fuel ratio is the average daily fuel ratio of a certain day before the shutdown. The furnace condition on the selected date must be similar to the current furnace condition.

[0008] S3. Calculate the volume V of a batch of material. i V i The sum of the masses of all the materials fed into the furnace in a batch, divided by their bulk density.

[0009] ;

[0010] S4, Calculate the standard material speed S 标The standard material rate is calculated based on the current batch volume V, under the condition that the air volume and oxygen content remain constant. 标 The average feed rate for the selected date must be calculated based on furnace conditions on that date that are similar to the current furnace conditions.

[0011]

[0012] ;

[0013] S5. Calculate the cumulative fuel ratio FR 休 FR 休 =Standard batch coke ratio + Cumulative pulverized coal injection rate / (P) 休 (Each batch of standard material batches of molten iron generated)

[0014] ;

[0015] S6. Adjust the hourly fuel ratio FR based on the difference between the cumulative fuel ratio FR and the standard fuel ratio. h FR h =Standard batch coke ratio + Hourly pulverized coal injection rate / (P) 休h (Each batch of standard material batches of molten iron generated)

[0016] ;

[0017] S7. By controlling the material speed of each batch S i Ensure hourly fuel ratio level

[0018] ;

[0019] S8. By controlling the hourly fuel ratio, the material flow rate and cumulative fuel ratio are kept at a reasonable level.

[0020] Beneficial Effects: This invention effectively solves the problem of reliance on personal experience and large deviations in fuel ratio control before blast furnace shutdown by establishing a standardized fuel ratio calculation and control process. This method can accurately guide the judgment and balancing of furnace temperature trends during the charging process, significantly improving the accuracy and stability of fuel ratio control and reducing uncertainties caused by differences in operating habits. By dynamically adjusting the feed rate and hourly fuel ratio, it ensures smooth furnace operation and stable furnace temperature transition, thereby guaranteeing timely and normal blast furnace shutdown and avoiding risks caused by abnormal furnace temperature fluctuations. It is applicable to blast furnace operations of various furnace capacities and has wide applicability and reliability. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method for precisely controlling the blast furnace fuel ratio before shutdown according to the present invention. Detailed Implementation

[0022] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example

[0024] A certain 5000m 3 The blast furnace of this type has a blast volume of 7000 m³ / h before shutdown. 3 / min, oxygen content 28000m 3 / h, based on the furnace conditions, the average daily fuel ratio of the previous day (similar to the current furnace conditions) of 493kg / t is selected as the standard fuel ratio.

[0025] The furnace temperature before the rest blast material is charged is 1510℃. The reduction rate of ore in the rest blast material under the tuyeres is calculated as 15kg / t higher than that in normal production.

[0026] The previous day's batch count was 133. Based on the current ore and coke batch counts, the previous day's batch count was 132.5. The standard feed rate Sstandard was calculated as 1440 / 132.5 = 10.87 min / batch.

[0027] Calculate the cumulative fuel ratio for the shutdown shift. The fuel ratio for the first hour is 490 kg / t, which exceeds the range of 493 ± 1 kg / t. Based on the technical requirements, the hourly fuel ratio is increased, with a target hourly fuel ratio of 494 kg / t.

[0028] In the second hour, the feed rate Si for the first batch was 11.4 min / batch, which was higher than the standard feed rate. The calculated cumulative fuel ratio was 491.2 kg / t, which was lower than the control range. The hourly fuel ratio was increased further, with a target of 494 kg / t. In the second hour, the feed rate Si for the second batch was 11.5 min / batch, which was higher than the standard feed rate. The calculated cumulative fuel ratio was 492.5 kg / t, which was within the control range. The subsequent hourly fuel ratio was controlled according to the standard fuel ratio of 493 kg / t.

[0029] The cumulative fuel ratio for the shutdown shift was calculated. The cumulative fuel ratio for the first 5 hours was 494.2 kg / t, which exceeds the range of 493 ± 1 kg / t. According to the technical requirements, the hourly fuel ratio was reduced to a target hourly fuel ratio of 492 kg / t.

[0030] In the 6th hour, the feed rate Si for the first batch was 11.4 min / batch, higher than the standard feed rate. The hourly fuel ratio was reduced to a target of 492 kg / t. In the 6th hour, the feed rate Si for the second batch was 11.0 min / batch, higher than the standard feed rate. The hourly fuel ratio was reduced to a target of 492 kg / t. In the 6th hour, the feed rate Si for the third batch was 10.5 min / batch, lower than the standard feed rate. The calculated cumulative fuel ratio was 494.1 kg / t, higher than the control range. The hourly fuel ratio was further reduced to a target of 492 kg / t. In the 6th hour, the feed rate Si for the fourth batch was 10.5 min / batch, lower than the standard feed rate. The calculated cumulative fuel ratio was 493.8 kg / t, reaching the control range. Subsequent hourly fuel ratios were controlled according to the standard fuel ratio of 493 kg / t.

[0031] In the 8th hour, the cumulative fuel ratio was 493.2 kg / t, the average material rate was 10.9 min / batch, and the furnace temperature under the tuyeres rose to 1540℃, at which point the blast furnace was shut down.

[0032] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for controlling the fuel ratio before shutting down an ironmaking blast furnace, characterized in that, Includes the following steps: S1. Increase the furnace temperature before shutdown by controlling the reduction rate of ore in the tuyeres; S2. Calculate the standard fuel ratio FR. The standard fuel ratio is the average daily fuel ratio of a certain day before the shutdown. The furnace condition on the selected date must be similar to the current furnace condition. S3. Calculate the volume V of a batch of material. i V i It is the sum of the masses of all the furnace feed materials in a batch, divided by their bulk density. S4, Calculate the standard material speed S 标 The standard material rate is calculated based on the current batch volume V, under the condition that the air volume and oxygen content remain constant. 标 The average material rate for the selected date must be calculated based on furnace conditions on that date, which must be similar to the current furnace conditions. S5. Calculate the cumulative fuel ratio FR 休 FR 休 =Standard batch coke ratio + Cumulative pulverized coal injection rate / (P) 休 × the amount of molten iron generated in a standard batch). S6. Adjust the hourly fuel ratio FR based on the difference between the cumulative fuel ratio FR and the standard fuel ratio. h FR h =Standard feed coke ratio + Hourly pulverized coal injection rate / (P) 休h × the amount of molten iron generated in a standard batch). S7. By controlling the material speed of each batch S i Ensure the hourly fuel ratio is at a certain level; S8. By controlling the hourly fuel ratio, the material flow rate and cumulative fuel ratio are kept at a reasonable level.

2. The method for controlling the fuel ratio before shutdown of a blast furnace according to claim 1, characterized in that, Step S1 is as follows: If the furnace temperature is normal or sufficient before the resting blast material is charged, the reduction rate of ore in the resting blast material under the tuyere is calculated as 15 kg / t higher than that in normal production; if the furnace temperature is lower than that in normal production before the resting blast material is charged, the reduction rate of ore in the resting blast material under the tuyere is calculated as (15 + 0.5 × temperature difference) kg / t higher than that in normal production.

3. The method for controlling the fuel ratio before shutdown of a blast furnace according to claim 1, characterized in that, In step S3, V i The calculation method is as follows: 。 4. The method for controlling the fuel ratio before shutdown of a blast furnace according to claim 1, characterized in that, In step S4, S 标 The calculation method is as follows: 。 5. The method for controlling the fuel ratio before shutdown of a blast furnace according to claim 1, characterized in that, In step S5, P 休 The calculation method is as follows: 。 6. The method for controlling the fuel ratio before shutdown of a blast furnace according to claim 1, characterized in that, In step S6, P 休h The calculation method is as follows: 。 7. The method for controlling the fuel ratio before shutdown of a blast furnace according to claim 1, characterized in that, In step S7, S i The calculation method is as follows: 。

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