A method for controlling the amount of coke added to the center of a blast furnace

Abstract

The invention discloses a method for controlling the amount of coke added to a blast furnace. The method comprises the following steps: using the blast furnace air supply ratio to judge the smooth running condition of the blast furnace; sampling and analyzing the furnace dust and molten iron of the blast furnace with poor smooth running, and obtaining the carbon content of the furnace dust and the carbon content of the molten iron of the current blast furnace; when the carbon content of the furnace dust is between 30% and 40% and the carbon content of the molten iron is between 4.6% and 4.8%, it is determined that the amount of coke added to the center of the blast furnace is excessive in a short period; when the carbon content of the furnace dust is between 30% and 40% and the carbon content of the molten iron is between 4.8% and 5.4%, it is determined that the amount of coke added to the center of the blast furnace is excessive in a long period; When the carbon content of dust is between 10-20% and the carbon content of molten iron is between 4.6-4.8%, it is determined that the central coke amount is in a short-term shortage. When the carbon content of furnace dust is between 10-20% and the carbon content of molten iron is between 4-4.6%, it is determined that the central coke amount is in a long-term shortage. The present invention uses daily monitoring data to judge the furnace condition of the central coke-adding blast furnace, accurately identify whether the central coke amount in the current blast furnace condition is excessive or insufficient, and make targeted adjustments to achieve stable and smooth operation of the blast furnace and optimize indicators.

Description

Technical Field

[0001] The invention belongs to the technical field of blast furnace smelting, and particularly relates to a method for controlling the amount of coke added to a blast furnace center. Background Art

[0002] The blast furnace operating system is divided into the top charging system, the bottom blast system, the heat system, the slag formation system, and the iron tapping system. The top charging system directly influences the distribution of gas flow in the upper part of the blast furnace and is the key to the blast furnace operation. The top charging system refers to the method by which charge is loaded into the furnace, including the loading sequence, loading method, the inclination of the distribution chute, the charge line, and the batch weight. Modern blast furnaces have bell-less roofs, and the distribution chute is the primary distribution equipment. The distribution chute rotates 360 degrees circumferentially and can be tilted within a certain range, allowing the charge to be distributed anywhere within the blast furnace. Adjustments to the top charging system of modern blast furnaces primarily control the placement and amount of charge on the furnace throat cross-section.

[0003] The upper charging system of modern blast furnaces can be divided into two types of distribution systems: center coking and non-center coking (non-center coking is also called platform funnel). The center coking distribution system has the advantages of being conducive to the development of center airflow, enhancing the adaptability to raw materials and fuels, and improving the oxygen enrichment rate, thereby increasing production. The key to the center coking distribution system lies in the center coking amount. Too little center coking is not conducive to the development of center airflow, and the blast furnace's smooth flow is poor; too much center coking can develop center airflow in the early stage, the blast furnace air volume will increase, and the smooth flow will improve. However, as the center coke column increases, the air and liquid permeability of the furnace hearth deteriorates, and the blast furnace's smooth flow will also deteriorate. Insufficient or excessive center coking will result in a decrease in blast furnace air volume and a deterioration in smooth flow.

[0004] In order to improve the technical indicators of the central coke-adding blast furnace, how to accurately identify whether the central coke amount in the current blast furnace condition is excessive or insufficient, so as to make targeted adjustments and accurately correct the central coke amount of the blast furnace, so as to achieve stable and smooth operation of the blast furnace and improve the economic and technical indicators of the central coke-adding blast furnace has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] Center-coke charging technology, first developed by Kobe Steel in Japan in the 1980s, is a blast furnace charging method. This involves adding a certain amount of coke from the top of the furnace toward the center to reduce the ore-to-coke ratio in the center. This improves air permeability and creates a chimney-like "air hole" in the center of the blast furnace. Existing technologies have made significant improvements to the charging system, adopting a charging system that suppresses edge airflow and appropriately promotes center airflow. However, the inability to accurately adjust the amount of center-coke charging still exists, resulting in poor overall furnace performance and high fuel consumption.

[0006] The applicant's research has found that increasing the amount of central coke immediately reduces the ore-to-coke ratio in the central region of the upper charge column, widens the air windows in the central region of the blast furnace, improves central air permeability, and increases the blast furnace air volume in the short term. However, if excessive central coke is added, exceeding the normal consumption of the central coke column, the excess central coke will reach the furnace hearth, causing the central coke column to become even larger, which in turn affects the air and liquid permeability of the furnace hearth and reduces the blast furnace air volume. Analysis of the carbon content of furnace dust and molten iron in blast furnaces with different amounts of central coke revealed the following pattern: excessive central coke addition increases the carbon content of both furnace dust and molten iron within a certain range, with changes in the carbon content of the dust occurring in a short-term cycle, while changes in the carbon content of the molten iron occur over a long period.

[0007] Through in-depth research, the applicant discovered that the principle is as follows: the carbon content in the furnace dust mainly comes from coke. The more coke is added to the center, the larger the central coke bag in the blast furnace charge column, the larger the air window in the central area of the blast furnace will be, the more coke will be dissolved and gasified, and more coke powder will be blown out and enter the furnace dust, which will be manifested as an increase in the carbon content in the furnace dust. The central dead coke column of the furnace is in dynamic equilibrium, which is constantly consumed and produced. The increase or decrease in the amount of central coke added for a period of time can directly affect the volume and replacement rate of the dead coke pile in the furnace. When the smelting conditions are constant, the more coke is added to the center, the larger the central dead coke column. The larger the volume of the central dead coke column, the longer the replacement cycle of the dead coke pile, the more serious the pulverization of the furnace coke, the longer the contact cycle between the molten iron circulation in the furnace and the furnace coke, the increased carburizing reaction of the molten iron, and ultimately the increase in the carbon content of the molten iron within a certain range.

[0008] When excessive coke is added to the center, the carbon content of the furnace dust increases to an upper limit. At this point, the carbon content of the molten iron remains within normal limits in the short term, as the replacement of the central dead coke column is a long-term process. However, if excessive coke is added to the center continuously, the volume of the central dead coke column begins to increase, the replacement cycle of the dead coke pile becomes longer, and the carburization reaction of the molten iron increases, ultimately causing the carbon content of the molten iron to increase within a certain range.

[0009] The purpose of the present invention is to provide a method for regulating the amount of central coke added to a blast furnace. By using daily monitoring data, the furnace condition of the central coke-added blast furnace is judged, and the central coke amount of the current blast furnace condition is accurately identified as excessive or insufficient, and targeted adjustments are made to achieve stable and smooth operation of the blast furnace and optimization of indicators.

[0010] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0011] A method for controlling the amount of coke added to a blast furnace center comprises the following steps:

[0012] (1) Use the blast furnace air supply ratio to judge the blast furnace's smooth operation;

[0013] (2) Sampling and analyzing the furnace dust and molten iron of the blast furnace with poor forward performance to obtain the carbon content of the current blast furnace dust and the carbon content of the molten iron;

[0014] (3) When the blast furnace is not running smoothly, the carbon content of the furnace dust is in the upper limit range of 30-40%, and the carbon content of the molten iron is in the normal range of 4.6-4.8%, it is determined that the central coke amount is in a short-term excess; then the central coke amount is reduced until the carbon content of the furnace dust returns to the normal range of 20-30%;

[0015] When the blast furnace is not running smoothly, the carbon content of the furnace dust is within the upper limit of 30-40%, and the carbon content of the molten iron is within the upper limit of 4.8-5.4%, it is determined that the central coke amount is in a state of excessive for a long period of time. In this case, the central coke amount is reduced and maintained for a long time until the carbon content of the molten iron returns to the normal range of 4.6-4.8%.

[0016] When the blast furnace is not running smoothly, the carbon content of the furnace dust is in the lower limit range of 10-20%, and the carbon content of the molten iron is in the normal range of 4.6-4.8%, it is determined that the central coke quantity is in a short-term shortage; the central coke quantity is increased until the carbon content of the furnace dust returns to the normal range of 20-30%;

[0017] When the blast furnace is running poorly, the carbon content of the furnace dust is at the lower limit range of 10-20%, and the carbon content of the molten iron is at the lower limit range of 4-4.6%, it is determined that the central coke quantity is in a state of long-term deficiency; the central coke quantity is increased and maintained for a long time until the carbon content of the molten iron returns to the normal range of 4.6-4.8%.

[0018] According to the above scheme, the blast furnace air volume in step 1 is divided by the actual blast furnace capacity to obtain the blast furnace air supply ratio.

[0019] According to the above scheme, for an actual furnace capacity of 2000m 3 For the following blast furnaces, an air supply ratio lower than 1.7 is considered to be poorly run.

[0020] According to the above scheme, for the actual furnace capacity of 2000-3000m 3 For blast furnaces, an air supply ratio lower than 1.65 is considered to be poorly run.

[0021] According to the above scheme, for the actual furnace capacity of 3000-4000m 3 For blast furnaces, an air supply ratio lower than 1.6 is considered to be poorly run.

[0022] According to the above scheme, for the actual furnace capacity of 4000-5000m 3 For blast furnaces, an air supply ratio lower than 1.55 is considered to be poorly run.

[0023] According to the above scheme, for furnaces with actual capacity greater than 5000m 3 For blast furnaces, an air supply ratio lower than 1.5 is considered to be poorly run.

[0024] According to the above scheme, in step 3, when the blast furnace runs poorly, the carbon content of the furnace dust is within the normal range of 20-30%, and the carbon content of the molten iron is within the normal range of 4.6-4.8%, it is determined that the central coke amount is appropriate, and the distribution of the ore-coke ratio at the edge of the material surface and the ring belt is adjusted until the blast furnace runs normally.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention corrects the central coke amount of the blast furnace online during blast furnace production, and determines the upper limit range, normal range and lower limit range of the blast furnace dust carbon content and the molten iron carbon content by monitoring the central coke blast furnace carbon content and the molten iron carbon content, accurately judges whether the central coke amount of the central coke blast furnace is appropriate, and makes targeted adjustments, thereby achieving accurate correction of the central coke amount, improving the smooth operation of the blast furnace, increasing the gas utilization rate, improving the blast furnace output, and reducing energy consumption and the cost per ton of iron.

[0027] The present invention utilizes daily monitoring data to judge the furnace condition of a center-coking blast furnace. First, the forward operation of the blast furnace is judged, and the central coke amount of the current blast furnace condition is accurately identified as excessive or insufficient. Furthermore, it is judged whether the unsuitability of the central coke amount is a long-term or short-term behavior, and targeted adjustments are made to achieve stable forward operation of the blast furnace and optimize indicators. When the central coke amount of the blast furnace is appropriate, not only the forward operation of the blast furnace is improved, but also the utilization rate of the blast furnace gas is increased, the fuel consumption of the blast furnace is reduced, which is beneficial to energy conservation and consumption reduction and low-carbon smelting, reduces the cost of pig iron, and can prevent the blast furnace body from thickening, which is beneficial to the maintenance of the blast furnace. DETAILED DESCRIPTION

[0028] The following examples further illustrate the technical solutions of the present invention but are not intended to limit the scope of protection of the present invention.

[0029] (1) Use the blast furnace air supply ratio to determine the blast furnace's smooth operation. The blast furnace air volume divided by the actual blast furnace capacity is the blast furnace air supply ratio. The blast furnace smooth operation judgment table is shown in Table 1. The blast furnace's smooth operation can be determined by calculating the blast furnace air supply ratio using the blast furnace's air volume and actual furnace capacity.

[0030] Table 1

[0031] <![CDATA[Actual furnace volume; m 3 > Air supply ratio normal range Furnace condition judgment Below 2000 ≥1.7 The air supply ratio is less than 1.7, which is considered as poor forward movement. 2000-3000 ≥1.65 The air supply ratio is lower than 1.65, which is considered as poor forward movement. 3000-4000 ≥1.6 The air supply ratio is less than 1.6, which is considered as poor forward movement. 4000-5000 ≥1.55 The air supply ratio is lower than 1.55, which is considered as poor forward movement. More than 5000 ≥1.5 If the air supply ratio is less than 1.5, it is judged as poor forward movement.

[0032] (2) The dust and molten iron of the blast furnace with poor forward performance are sampled and analyzed to obtain the current carbon content of the blast furnace dust and the carbon content of the molten iron; the present invention tracks the furnace conditions of the central coking blast furnace and determines the upper limit range, normal range, and lower limit range of the carbon content of the blast furnace dust and the carbon content of the molten iron, as shown in Table 2.

[0033] Table 2

[0034] Upper range % Normal range% Lower limit range% Carbon content of furnace dust 30-40 20-30 10-20 Carbon content of molten iron 4.8-5.4 4.6-4.8 4-4.6

[0035] (3) Monitor the current carbon content of blast furnace dust and molten iron, and make corresponding judgments and targeted adjustments, as shown in Table 3.

[0036] Table 3

[0037]

[0038] Example 1

[0039] The actual effective volume of a blast furnace is 3407m 3 ,Using the center coke distribution mode, the blast furnace distribution matrix is Air volume 5200m 3 / min, gas utilization rate 44%, daily output 7500t. The air supply ratio of this blast furnace is calculated to be 1.53, which is far lower than the normal air supply ratio of 1.6 for this furnace capacity, indicating that the blast furnace is not running properly.

[0040] Sampling and analysis of the blast furnace's dust and molten iron revealed a carbon content of 14% in the dust and 4.4% in the molten iron. Comparing these values with the ranges for blast furnace dust and molten iron, the carbon content in both the dust and molten iron is at the lower limit, indicating a long-term shortage of central coke.

[0041] Targeted adjustment, add 1 ring of center focus at corner 1 and maintain it for a long time, the air volume increases from 5200m 3 / min increased to 5500m 3 / min, the air supply ratio reached 1.62, the blast furnace ran smoothly, the gas utilization rate increased from the original 44% to 46%, the blast furnace fuel ratio was reduced by 10kg / t, the fuel cost was reduced by 20 yuan / t, and the output was increased to 8,000t per day.

[0042] Example 2

[0043] The actual effective volume of a blast furnace is 4117m 3 ,Using the center coke distribution mode, the blast furnace distribution matrix is Air volume 6300m 3 / min, gas utilization rate 43%, daily output 9100t. The air supply ratio of this blast furnace is calculated to be 1.58, which is lower than the normal air supply ratio of 1.6 for this furnace capacity, and it is judged that this blast furnace is not running properly.

[0044] Sampling and analysis of the blast furnace's dust and molten iron revealed a carbon content of 37% in the dust and 4.94% in the molten iron. Comparing these values with the ranges for blast furnace dust and molten iron, the carbon content in both the dust and molten iron is within the upper limit, indicating a long-term excess of central coke.

[0045] Targeted adjustment, reduce the center focus of corner 1 by 1 ring and maintain it for a long time, and the air volume is increased from 6300m 3 / min increased to 6800m 3 / min, the air supply ratio reached 1.65, the blast furnace ran smoothly, the gas utilization rate increased from the original 43% to 46%, the blast furnace fuel ratio was reduced by 15kg / t, the fuel cost was reduced by 30 yuan / t, and the output was increased to 10,000t per day.

[0046] Example 3

[0047] The actual effective volume of a blast furnace is 2811m 3 ,Using the center coke distribution mode, the blast furnace distribution matrix is Air volume 4700m 3 / min, gas utilization rate 43%, daily output 6500t. The air supply ratio of this blast furnace is calculated to be 1.67, which is lower than the normal air supply ratio of 1.7 for this furnace capacity, and it is judged that this blast furnace is not running properly.

[0048] Sampling and analysis of the blast furnace's dust and molten iron revealed a carbon content of 33% in the dust and 4.8% in the molten iron. Comparing these figures with the ranges for blast furnace dust and molten iron, the carbon content in the dust was within the upper limit, while the carbon content in the molten iron was within the normal range, indicating a short-term excess of central coke.

[0049] Targeted adjustment, reduce the center focus of the corner position 1 by 1 ring and restore it after two days, the air volume is reduced from 4700m 3 / min increased to 5100m 3 / min, the air supply ratio reached 1.81, the blast furnace ran smoothly, the gas utilization rate increased from the original 43% to 46%, the blast furnace fuel ratio was reduced by 15kg / t, the fuel cost was reduced by 30 yuan / t, and the output was increased to 7,000t per day.

[0050] Through the above operations, the carbon content of the dust and the carbon content of the molten iron in the central coking blast furnace can be monitored, and it can be accurately judged whether the central coking amount of the central coking blast furnace is appropriate, and targeted adjustments can be made. The accurate correction of the central coking amount can be achieved, thereby improving the smooth operation of the blast furnace, increasing the gas utilization rate, increasing the blast furnace output, and reducing energy consumption and the cost per ton of iron.

Claims

1. A method for controlling the amount of coke added to a blast furnace, characterized in that The following steps are involved: (1) Use the blast furnace air supply ratio to judge the blast furnace's smooth operation; (2) Sampling and analyzing the furnace dust and molten iron of the blast furnace with poor forward performance to obtain the carbon content of the current blast furnace dust and molten iron; (3) When the blast furnace is running poorly, the carbon content of the furnace dust x is in the upper limit range of 30% < x ≤ 40%, and the carbon content of the molten iron y is in the normal range of 4.6% ≤ y ≤ 4.8%, it is determined that the central coke amount is in a short-term excess; then the central coke amount is reduced and the carbon content of the furnace dust x returns to the normal range of 20% ≤ x ≤ 30%; When the blast furnace is not running smoothly, the carbon content x of the furnace dust is within the upper limit range of 30%<x≤40%, and the carbon content y of the molten iron is within the upper limit range of 4.8%<y≤5.4%, it is determined that the central coke amount is in a state of long-term excess. The central coke amount is reduced and maintained for a long time until the carbon content y of the molten iron returns to the normal range of 4.6%≤y≤4.8%; When the blast furnace is not running smoothly, the carbon content x of the furnace dust is in the lower limit range of 10≤x<20%, and the carbon content y of the molten iron is in the normal range of 4.6%≤y≤4.8%, it is determined that the central coke quantity is insufficient in the short term; then the central coke quantity is increased until the carbon content x of the furnace dust returns to the normal range of 20%≤x≤30%; When the blast furnace runs poorly, the carbon content x in the furnace dust is at the lower limit range of 10≤x<20%, and the carbon content y in the molten iron is at the lower limit range of 4%≤y<4.6%, it is determined that the central coke quantity is in a long-term insufficient state; the central coke quantity is increased and maintained for a long time until the carbon content y in the molten iron returns to the normal range of 4.6%≤y≤4.8%.

2. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein In step 1, the blast furnace air volume is divided by the actual blast furnace capacity to obtain the blast furnace air supply ratio.

3. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein For actual furnace capacity of 2000m 3 For the following blast furnaces, an air supply ratio lower than 1.7 is considered to be poorly run.

4. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein For actual furnace capacity of 2000-3000m 3 For blast furnaces, an air supply ratio lower than 1.65 is considered to be poorly run.

5. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein For actual furnace capacity 3000-4000m 3 For blast furnaces, an air supply ratio lower than 1.6 is considered to be poorly run.

6. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein For actual furnace capacity of 4000-5000m 3 For blast furnaces, an air supply ratio lower than 1.55 is considered to be poorly run.

7. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein For actual furnace capacity greater than 5000m 3 For blast furnaces, an air supply ratio lower than 1.5 is considered to be poorly run.

8. The method for controlling the amount of coke added to the center of a blast furnace as claimed in claim 1, wherein In step 3, when the blast furnace runs poorly, the carbon content x of the furnace dust is within the normal range of 20%≤x≤30%, and the carbon content y of the molten iron is within the normal range of 4.6%≤y≤4.8%, it is determined that the central coke amount is appropriate. The distribution of the ore-coke ratio at the edge of the material surface and the ring belt is adjusted until the blast furnace runs normally.

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