Diffusion control method for improving converter gas recovery amount

Abstract

The invention relates to the technical field of metallurgy, and particularly discloses a diffusion control method for improving the recovery amount of converter gas, which comprises the following steps: 1) a converter gas system collects the O2 content and CO content in converter gas, and the converter gas system collects the opening and closing of an oxygen shut-off valve; 2) setting diffusion conditions of converter gas recovery in the converter gas system: O2 is more than 1% or CO is less than 3% or 60 seconds after an oxygen stop valve is closed; (3) controlling the converter gas to begin to be diffused by the converter gas system when the three diffusion conditions of the converter gas recovery are that O2 is more than 1 percent or CO is less than 3 percent or 60 seconds after the oxygen stop valve is closed and the three diffusion conditions meet the first condition; according to the diffusion control method for increasing the converter gas recovery amount, the converter gas recovery time is effectively prolonged, the total converter gas recovery amount is increased, the heat value of the recovered converter gas is slightly reduced, but the user requirements are completely met, and the converter gas recovery amount is increased.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly relates to a blow-off control method for increasing the recovery amount of converter gas. Background Art

[0002] The recovery of converter gas accounts for 80% - 90% of the total energy recovery in the converter process, which is a key link to reduce the energy consumption and energy cost of the converter process. Increasing the recovery amount of converter gas is of great significance for energy conservation, consumption reduction, cost reduction and efficiency improvement in the converter process.

[0003] During the converter blowing process, oxygen supply to the converter is controlled by opening and closing the oxygen cut-off valve. When the oxygen cut-off valve is opened, oxygen starts to enter the converter, and when the oxygen cut-off valve is closed, the oxygen flow rate is 0.

[0004] The traditional converter gas blow-off condition is generally that after the blowing is completed and the oxygen cut-off valve is closed, the converter gas starts to blow off. However, at this time, the C-O reaction inside the molten bath is still in progress, and there is still converter gas with a high concentration of CO in the primary dedusting system pipeline, resulting in energy waste.

[0005] In the Chinese patent document with the application number 202211635804.X, a method for increasing the recovery amount of converter gas is disclosed. The blow-off interlock condition of converter gas recovery is optimized, the recovery amount of converter gas is increased, and carbon emissions are reduced, with relatively significant economic benefits. The blow-off condition proposed in this patent is: when the converter blowing time is ≤ 5 min and the O2 content > 1 wt%, the system switches to the blow-off state; after the converter blowing time exceeds 5 min, when the O2 content > 1 wt% or when the CO content < 21 wt%, the system switches to the blow-off state. Under normal circumstances, the smelting cycle for smelting one furnace of steel in a converter is usually about 30 minutes, and the oxygen blowing time is generally 12 - 18 minutes. CO recovery is carried out during the oxygen blowing period, and the CO recovery time is generally more than 8 minutes. In the actual production process, the condition "when the converter blowing time is ≤ 5 min and the O2 content > 1 wt%, the system switches to the blow-off state" hardly triggers and serves as a safety guarantee condition; while the condition "after the converter blowing time exceeds 5 min, when the O2 content > 1 wt% or when the CO content < 21 wt%, the system switches to the blow-off state" is the actual blow-off condition that will trigger. Under this condition, there are two conditions, namely "O2 content > 1 wt%" and "CO content < 21 wt%". When one of these conditions is triggered, the converter gas starts to blow off. Through Figure 1It can be seen from the curves of CO and O2 gas contents during the converter blowing cycle that at the end of each blowing cycle, when the O2 content is about 1%, the CO content is 8-10%, and when the CO content is about 21%, the O2 content is below 0.1%. Under normal conditions, the CO volume fraction in converter gas ≈ 1.11 * CO mass fraction, and the O2 volume fraction ≈ 0.97 * O2 mass fraction. Considering the conversion relationship between volume fraction and mass fraction, the main triggering condition during actual operation is that the CO content < 21wt%. It can be seen that there is still a large amount of CO that can be recovered when the O2 content is low.

[0006] Therefore, designing a blow-off control method to increase the recovery amount of converter gas and how to more efficiently increase the recovery amount of converter gas by optimizing the blow-off conditions of converter gas are technical problems that need to be solved by those skilled in the art currently. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a blow-off control method for increasing the recovery amount of converter gas. By optimizing the blow-off conditions of converter gas, under the condition of ensuring gas composition and system safety, all converter gas that can be recovered should be recovered. The average concentration of CO in the recovered converter gas is 50%-55%, and the calorific value of the gas is 6900-7000 kJ / m3, which can meet the requirements of converter gas users, and further realizes the dual goals of energy conservation and environmental protection.

[0008] The technical solution adopted by the present invention to solve its technical problems is: a blow-off control method for increasing the recovery amount of converter gas, including the following steps:

[0009] 1) The converter gas system collects the O2 content and CO content in the converter gas, and the converter gas system collects the opening and closing of the oxygen cut-off valve.

[0010] 2) Set the blow-off conditions for converter gas recovery in the converter gas system: O2 > 1% or CO < 3% or 60 s after the oxygen cut-off valve is closed.

[0011] 3) When any one of the three blow-off conditions for converter gas recovery, i.e., O2 > 1% or CO < 3% or 60 s after the oxygen cut-off valve is closed, is satisfied, the converter gas system controls the converter gas to start blowing off.

[0012] Specifically, in step 1), the converter gas system collects and detects the O2 content and CO content in the converter gas through a gas analyzer.

[0013] Specifically, the blow-off condition O2 > 1% in step 2) is the condition with the highest triggering frequency. When this blow-off condition is triggered, the CO content is in the range of 6-12%.

[0014] Specifically, the gas emission condition of CO < 3% in step 2) is set due to the too low CO content caused by the gas component fluctuation in the initial stage of smelting and during the smelting process.

[0015] Specifically, the 60s after the oxygen cut-off valve is closed in the gas emission condition of step 2) is set for the abnormal gas component monitoring caused by the failure of the monitoring instrument.

[0016] Specifically, in the converter gas system of step 3), a monitoring device for the O2 content is provided at the inlet of the gas holder to ensure that the O2 concentration of the recovered converter gas meets the requirements.

[0017] The present invention has the following beneficial effects:

[0018] The gas emission control method for increasing the recovery amount of converter gas designed by the present invention optimizes the gas emission conditions for converter gas recovery, effectively prolongs the recovery time of converter gas, increases the total recovery amount of converter gas. Although the calorific value of the recovered converter gas slightly decreases, it fully meets the user's requirements, that is, the recovery amount of converter gas is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 For the actual trigger point of converter gas emission during the actual use process and the comparison with the trigger point of the existing technical solution Figure 1 。

[0020] Figure 2 For the actual trigger point of converter gas emission during the actual use process and the comparison with the trigger point of the existing technical solution Figure 2 。

[0021] Figure 3 For the actual trigger point of converter gas emission during the actual use process and the comparison with the trigger point of the existing technical solution Figure 3 。

[0022] Figure 4 For the actual trigger point of converter gas emission during the actual use process and the comparison with the trigger point of the existing technical solution Figure 4 。 DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the technical solutions in the embodiments of the present invention will be further described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] A gas emission control method for increasing the recovery amount of converter gas effectively prolongs the recovery time of converter gas, increases the total recovery amount of converter gas. Although the calorific value of the recovered converter gas slightly decreases, it fully meets the user's requirements, that is, the recovery amount of converter gas is increased.

[0025] 1. The converter gas system collects and detects the O2 content and CO content in the converter gas through a gas analyzer, and collects the opening and closing of the oxygen cut-off valve in the converter gas system.

[0026] 2. The converter gas system sets the gas release conditions for converter gas recovery: O2 > 1% or CO < 3% or 60 s after the oxygen cut-off valve is closed.

[0027] 3. When one of the three gas release conditions for converter gas recovery, namely O2 > 1% or CO < 3% or 60 s after the oxygen cut-off valve is closed, is met, the converter gas system controls the converter gas to start releasing.

[0028] The gas release condition of O2 > 1% is the condition with the highest trigger frequency. When this gas release condition is triggered, the CO content is in the range of 6 - 12%. To ensure that the CO content is not too low due to fluctuations in gas components during the initial stage and process of smelting, the gas release condition of CO < 3% is added. To ensure abnormal monitoring of gas components caused by faults in monitoring instruments, etc., the gas release condition of 60 s after the oxygen cut-off valve is closed is added. The converter gas system is equipped with a monitoring device for O2 content at the inlet of the gas holder to ensure that the O2 concentration of the recovered converter gas meets the requirements.

[0029] Example 1

[0030] Set the gas release conditions as: O2 > 1%, CO < 3%, 60S after the oxygen cut-off valve is closed. When one of the three conditions is met, the converter gas starts to release.

[0031] The gas release conditions include 3 conditions in total. Among them, "O2 > 1%" and "60S after the oxygen cut-off valve is closed" are conditions to ensure that the O2 content in the recovered converter gas remains at a low level, and "CO < 3%" is a condition to ensure that the calorific value of the recovered converter gas remains at a high level.

[0032] Figures 1 to 4 They are respectively a comparison diagram of the actual trigger points of converter gas release during the actual use of this patent and the trigger points of the existing technical solutions. It can be seen from the figure that by adopting the gas release conditions of this patent, the recovery duration of converter gas is effectively extended by 60 - 75 s, and the actual measured recovery volume of converter gas increases by about 10 m 3 / t. Taking an annual steel production of 10 million tons as an example, the economic benefit per ton of steel increases by 18 million yuan; the annual carbon emission reduction is 55,000 tons, and the economic benefit is significant. Figures 1 to 4 The CO and O2 contents of the trigger points in the existing technical solutions are evaluated by volume fraction. Affected by the conversion between volume fraction and mass fraction, the actual start release point of the existing technical solutions is earlier than the position shown in the figure, that is, the beneficial effects of this application are higher than the above evaluation effects.

[0033] Under the condition of ensuring gas composition and system safety, with the gas composition as the core, all converter gases should be collected as much as possible. The gas recovery time is increased by 60 - 75 s, and the converter gas recovery volume is increased by about 10 m 3 / t, reducing the energy consumption and energy cost of the converter process, reducing the CO concentration in the air, achieving the dual goals of environmental protection and energy conservation, and can be popularized to the converter gas recovery applications in the domestic same industry.

[0034] The present invention is not limited to the above embodiments. Any person should know that the structural changes made under the inspiration of the present invention, as long as they have the same or similar technical solutions as the present invention, all fall within the protection scope of the present invention.

[0035] The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A method for controlling the gas release to increase the recovery amount of converter gas, characterized in that, It includes the following steps: 1) The converter gas system collects the O2 content and CO content in the converter gas, and the converter gas system collects the opening and closing of the oxygen cut-off valve; 2) The converter gas system sets the gas discharge conditions for converter gas recovery: O2 > 1% or CO < 3% or 60 s after the oxygen cut-off valve is closed; 3) When one of the three gas discharge conditions for converter gas recovery, i.e., O2 > 1% or CO < 3% or 60 s after the oxygen cut-off valve is closed, is met, the converter gas system controls the converter gas to start discharging.

2. The blow-off control method for increasing the recovery amount of converter gas according to claim 1, characterized in that In step 1), the O2 content and CO content in the converter gas are collected and detected by the converter gas system through a gas analyzer.

3. The gas blowing control method for increasing the converter gas recovery amount according to claim 1, characterized in that, The gas discharge condition O2 > 1% in step 2) is the condition with the highest trigger frequency. When this gas discharge condition is triggered, the CO content is in the range of 6 - 12%.

4. The blow-off control method for increasing the recovery amount of converter gas according to claim 1, characterized in that, The gas discharge condition CO < 3% in step 2) is set for the too low CO content caused by the gas component fluctuation during the initial stage of smelting and the smelting process.

5. The blow-off control method for increasing the recovery amount of converter gas according to claim 1, characterized in that, The gas discharge condition 60 s after the oxygen cut-off valve is closed in step 2) is set for the abnormal gas component monitoring caused by the failure of the monitoring instrument.

6. The gas discharge control method for increasing the converter gas recovery amount according to claim 1, characterized in that, In step 3), the converter gas system is provided with a monitoring device for the O2 content at the inlet of the gas holder to ensure that the O2 concentration of the recovered converter gas meets the requirements.

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