CN113293246A - Method for judging disappearance of reflow zone in furnace shutdown process - Google Patents

Abstract

The invention relates to the field of ferrous metallurgy. A method for judging the disappearance of a reflow zone in a blowing-out process comprises the steps of firstly, calculating the total oxygen amount and the total nitrogen amount in a blast furnace according to the air amount BV and the humidification amount BH of the blast furnace and the total nitrogen amount in the blast furnace; step two, calculating the total oxygen content ratio in the top gas and the total nitrogen content ratio in the top gas by analyzing the components of the top gas of the blast furnace; step three, calculating the ratio of oxygen to nitrogen in the blast furnace (O2/N2)_{Into the furnace}And furnace top oxygen to nitrogen ratio (O2/N2)_{Furnace roof}Then, find (O2/N2)_{Into the furnace}And (O2/N2)_{Furnace roof}When M is greater than 0.95, the reflow band is still present, otherwise the reflow band has disappeared.

Description

Method for judging disappearance of reflow zone in furnace shutdown process

Technical Field

The invention relates to the field of ferrous metallurgy.

Background

The disappearance of the reflow zone in the blast furnace shutdown process is an important node, the traditional judgment method in the blast furnace shutdown process is to judge according to the components of the furnace top gas, when the CO2 in the components of the gas has an inflection point, whether the reflow zone has disappeared is judged according to the inflection point, the hysteresis of manual sampling analysis and measurement of the components of the furnace top gas in the furnace shutdown process is limited, meanwhile, the data before and after the reflow zone disappears are needed to judge whether the inflection point appears in the CO2, the actual judgment lags behind the actual disappearance, in order to ensure the safety in the furnace shutdown process, measures such as reducing the air and the like are adopted when the CO2 descends to a certain value and the material line descends to the lower part of the furnace body, so that the furnace shutdown process is slowed down, the traditional method cannot reflect whether the reflow zone disappears in time, and cannot provide accurate basis for the operation of key parameters of the blast furnace shutdown operation.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: how to accurately judge whether the reflow zone disappears in the blowing-out process of the blast furnace. The technical scheme adopted by the invention is as follows: a method for judging the disappearance of a reflow zone in the blowing-out process comprises the following steps

Step one, the blast furnace air feeding amount BV, the humidifying amount BH and the total nitrogen gas N2 are fed into the blast furnace_{(Nitrogen is introduced into the furnace)}Calculating total oxygen amount sigma O in furnace_{2 into the furnace}Total nitrogen amount in furnace_{2 into the furnace}

Wherein the unit of the air volume BV entering the furnace is m³Min, the unit of the humidification BH is t/h, and the total nitrogen gas introduced into the furnace is N2_{(Nitrogen is introduced into the furnace)}Unit is m³Min, total oxygen fed to furnace Sigma O_{2 into the furnace}Unit m³Min, total nitrogen charged into furnace Σ N_{2 into the furnace}Unit is m³/min；

Step two, calculating the ratio sigma O of the total oxygen in the top gas by analyzing the components of the top gas of the blast furnace_{2 furnace roof}sigma-N ratio of total nitrogen in top gas_{2 furnace roof}

ΣN_{2 furnace roof}＝N2_{(furnace roof gas analyzer)}

Wherein, the total oxygen content in the top gas is sigma O_{2 furnace roof}Converting the oxygen content into m for the analysis of the top gas³Total nitrogen content sigma N in top gas_{2 furnace roof}For the analysis of the top gas, the nitrogen content is converted in m³CO is the carbon monoxide content of the top gas analysis, and the unit is m³，CO₂Analysis of the amount of carbon dioxide in m for the top gas³，η_COFor gas utilization, H₂The unit of the hydrogen gas amount is m for the analysis of the top gas³A is a conversion coefficient, and the value of A is 0.8-0.9;

step three, calculating the ratio of oxygen to nitrogen in the blast furnace (O2/N2)_{Into the furnace}And furnace top oxygen to nitrogen ratio (O2/N2)_{Furnace roof}

(O2/N2)_{Into the furnace}＝ΣO_{2 into the furnace}：ΣN_{2 into the furnace}

(O2/N2)_{Furnace roof}＝ΣO_{2 furnace roof}：ΣN_{2 furnace roof}

Then, find (O2/N2)_{Into the furnace}And (O2/N2)_{Furnace roof}Ratio M of

M＝(O2/N2)_{Into the furnace}：(O2/N2)_{Furnace roof}

When M is greater than 0.95, the reflow band is still present, otherwise, the reflow band has disappeared.

Whether the reflow zone exists in the blowing-out process of the blast furnace is an important basis for guiding the blowing-out operation, after the reflow zone disappears in the blowing-out process, because the resistance loss is reduced, the direct reduction heat consumption disappears, the blast furnace gas flow speed in the furnace is increased, the gas heat value is increased, the furnace top temperature control difficulty is increased, in order to ensure the blowing-out safety, the air reduction operation is required at the moment, and the proper furnace top water injection amount is controlled. If the melting zone disappears can be judged in real time, the blowing-out parameter can be accurately adjusted, which is not only beneficial to ensuring the blowing-out safety, but also beneficial to ensuring the blowing-out process. The invention fully considers the smelting principle of the blast furnace blowing-out process, deduces a calculation formula for judging whether the reflow zone disappears, judges whether the reflow zone disappears in real time by utilizing the functions of data acquisition, statistical calculation and visualization of a computer system, and can provide accurate basis for calculating the adjustment of the blowing-out operation parameters.

During the blast furnace shutdown process, the components of the top gas of the blast furnace are CO and CO₂、H₂、H₂O、N₂And the medium mainly including air quantity, humidification quantity and nitrogen quantity used for furnace shutdown is fed into the furnace, when the soft melting zone in the blast furnace exists, the oxygen in the ore continuously enters the gas so as to increase the O2/N2 ratio in the top gas, when the soft melting zone disappears, the ore does not exist, no redundant oxygen enters the top gas, according to the material conservation principle, after the soft melting zone disappears, the O2/N2 ratio of the top gas is consistent with the O2/N2 ratio in the gas fed into the furnace, and a judgment formula for judging whether the soft melting zone disappears can be established according to the principle. The invention collects the blast volume, the humidification volume and the nitrogen volume in the furnace during the blowing out period in real time, and counts the relationship between the utilization rate of hydrogen and the utilization rate of CO according to the big data analysis and regression method, and calculates the furnace top H through the furnace top gas analyzer and the gas utilization rate₂The amount of O produced is further determined by (O2/N2)_{Into the furnace}：(O2/N2)_{Furnace roof}The ratio between the two can judge whether the reflow band disappears, and when the ratio is close to 1, the reflow band can be judged to disappear.

The invention has the beneficial effects that: as the level of modern blast furnace equipment is continuously improved, the reliability and the precision of measurement and control equipment are greatly improved, the blast furnace air quantity, the oxygen quantity, the humidification quantity, a furnace top gas component analyzer, cooling N2 and the like can be accurately measured, the blast furnace air quantity, the oxygen enrichment, the humidification, the furnace entering nitrogen and other components can be tracked in real time, and the online judgment of whether the reflow zone exists in the furnace shutdown process is realized by utilizing a model formula for judging whether the reflow zone disappears. Whether the reflow zone exists during the furnace shutdown can be accurately reflected in time in the furnace shutdown process. The adjustment time of the operation parameters during the blast furnace shutdown period can be guided. Is favorable for ensuring the safety of furnace blowing out and the furnace blowing out progress.

Drawings

FIG. 1 is a diagram of the relationship between the CO2 curve of the furnace top gas and the charge level position;

FIG. 2 is a diagram showing the relationship between the blowing-out M value and the charge level position;

FIG. 3 is a graph showing a comparison of air volume adjustments during a furnace shutdown.

Detailed Description

The following examples further illustrate embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples.

Firstly, a traditional measuring and calculating method is adopted, namely whether a reflow zone disappears or not is judged according to a method of turning point occurrence of CO2 content in coal gas analysis.

Taking the top CO2 curve of a certain blast furnace in the blowing-out process as an example, the zero position of the blast furnace burden line is 42 m, the central line elevation of a tuyere is 14.97 m, and the relation between the top gas CO2 curve and the level elevation of the burden surface in the blowing-out process is shown in figure 1:

as can be seen from fig. 1, the top gas CO2 starts to turn when the charge level is around 28 m, and according to the past experience, the parameters during the furnace shutdown start to be adjusted.

By using the method of the invention, the M value in the blowing-out process is calculated, and the relation between the M value and the charge level elevation in the blowing-out process is shown in figure 2:

as can be seen from fig. 2, when the level is around 25M, M is 1, and according to the calculation of the present invention, the adjustment of the blowing out period parameters is started.

Compared with the traditional judging method, the traditional method judges that the position of the charge level is about 3 meters higher than the position of the invention when the reflow zone disappears.

Taking the actual air flow operation adjustment during the blast furnace blowing out period as an example, the air flow adjustment plan is compared according to the M value and the content of the top gas CO 2. A comparison is shown in fig. 3. As can be seen from the figure, compared with the air volume adjustment based on the content of the furnace top gas CO2, the air volume control curve taking the M value as the reference is more accurate in adjustment and larger in air volume usage amount, and the blowing-out process of the air volume control curve taking the M value as the reference is faster due to the fact that the blowing-out process is related to the accumulated air volume.

TABLE 1 comparison of results

	Conventional methods	The method of the invention	Compared with the traditional method
				Cumulative air flow in ten thousand m3	400	400
When the furnace is shut down, h	22	19	3

Compared with the results, the blast furnace top gas CO2 is longer in furnace shutdown process according to the air quantity adjusting method, and the method is more representative than the traditional method.

Claims (1)

1. A method for judging the disappearance of a reflow zone in a blowing-out process is characterized in that: the method comprises the following steps of firstly, feeding air BV and humidification BH of a blast furnace, and feeding the total nitrogen N2 into the furnace_{(Nitrogen is introduced into the furnace)}Calculating total oxygen amount sigma O in furnace_{2 into the furnace}Total nitrogen amount in furnace_{2 into the furnace}

Wherein the unit of the air volume BV entering the furnace is m³Min, the unit of the humidification BH is t/h, and the total nitrogen gas introduced into the furnace is N2_{(Nitrogen is introduced into the furnace)}Unit is m³Min, total oxygen fed to furnace Sigma O_{2 into the furnace}Unit m³Min, total nitrogen charged into furnace Σ N_{2 into the furnace}Unit is m³/min；

Step two, calculating the ratio sigma O of the total oxygen in the top gas by analyzing the components of the top gas of the blast furnace_{2 furnace roof}sigma-N ratio of total nitrogen in top gas_{2 furnace roof}

ΣN_{2 furnace roof}＝N2_{(furnace roof gas analyzer)}

Wherein, the total oxygen content in the top gas is sigma O_{2 furnace roof}Converting the oxygen content into m for the analysis of the top gas³Total nitrogen content sigma N in top gas_{2 furnace roof}For the analysis of the top gas, the nitrogen content is converted in m³CO is the carbon monoxide content of the top gasIs m³，CO₂Analysis of the amount of carbon dioxide in m for the top gas³，η_COFor gas utilization, H₂The unit of the hydrogen gas amount is m for the analysis of the top gas³A is a conversion coefficient, and the value of A is 0.8-0.9;

step three, calculating the ratio of oxygen to nitrogen in the blast furnace (O2/N2)_{Into the furnace}And furnace top oxygen to nitrogen ratio (O2/N2)_{Furnace roof}

(O2/N2)_{Into the furnace}＝ΣO_{2 into the furnace}：ΣN_{2 into the furnace}

(O2/N2)_{Furnace roof}＝ΣO_{2 furnace roof}：ΣN_{2 furnace roof}

Then, find (O2/N2)_{Into the furnace}And (O2/N2)_{Furnace roof}Ratio M of

M＝(O2/N2)_{Into the furnace}：(O2/N2)_{Furnace roof}

When M is greater than 0.95, the reflow band is still present, otherwise, the reflow band has disappeared.

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