KR101848181B1 - Evaluation method of cokes quality in the blast furnace based on hygrogen injection - Google Patents

Abstract

The present invention relates to a method to evaluate quality of cokes in accordance with hydrogen injection in a blast furnace, capable of measuring reactivity of cokes by hydrogen. According to one embodiment of the present invention, the method comprises: a step of supplying only carbon dioxide into a blast furnace and measuring a change in a cokes reactivity index in accordance with increase of a supply amount of carbon dioxide, wherein a saturated cokes reactivity index is set as a reference cokes reactivity index when the cokes reactivity index is saturated; a step of supplying carbon dioxide and inert gas into the blast furnace at the same time, and measuring a change in the cokes reactivity index in accordance with a partial pressure of carbon dioxide, wherein a partial pressure of carbon dioxide of a reaction condition having the same cokes reactivity index as the reference cokes reactivity index is deduced as a reference partial pressure of carbon dioxide; a step of supplying carbon dioxide and hydrogen into the blast furnace at the same time under the reference partial pressure of carbon dioxide and measuring a change in the cokes reactivity index in accordance with an amount or partial pressure of supplied hydrogen; and a step of evaluating the cokes reactivity index in accordance with the amount or partial pressure of supplied hydrogen from the measured cokes reactivity index and the reference cokes reactivity index.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for evaluating coke quality in a blast furnace,

The present invention relates to a coke quality evaluation method, and more particularly, to a method of evaluating coke quality at the time of introducing hydrogen into a blast furnace.

In the blast furnace operation, the iron ore charged in the upper part of the blast furnace is melted by the hot wind supplied through the tuyeres to produce molten iron including molten iron and slag, and the molten metal accumulated in the furnace is continuously discharged through the outlet . At this time, coke is applied as the heat source of the above-mentioned process. The coke may be produced by heating and pulverizing the coal in a coke oven plant.

On the other hand, there is a CSR (Coke Strength after Reaction) which is widely used as an indicator of the coke oven differentiation characteristics. CSR decreases as the coke reactivity index, the Coke Reactivity Index (CRI), increases. The coke needs to be managed to maintain a certain value of CSR within the blast furnace, in order to serve as a vent for the iron ores provided in the blast furnace.

Recently, in order to reduce the amount of carbon dioxide discharged after the reaction from the blast furnace, a technique of blowing hydrogen into the blast furnace has been developed. Currently, it is a technique that is being tested at an experimental stage. When hydrogen is injected into the blast furnace, it is necessary to study the change of the charge.

As a background technique related to the present invention, Korean Patent Laid-Open Publication No. 10-2016-0105476 (method of operating the blast furnace) is known.

The present invention provides a method for measuring coke reactivity by hydrogen when blowing hydrogen into a blast furnace.

A method for evaluating coke quality according to an input of hydrogen into a blast furnace in accordance with an aspect of the present invention is disclosed. The method for evaluating coke quality comprises the steps of supplying only carbon dioxide to a blast furnace and measuring a change in the reactivity index of the coke as the amount of supplied carbon dioxide is increased, wherein the saturated coke reactivity index is set as a reference coke reactivity index when the coke reactivity index is saturated ; The carbon dioxide partial pressure of the reaction condition having the same coke reactivity index as the reference coke reactivity index is determined as a reference carbon dioxide partial pressure by supplying carbon dioxide and an unreactive gas together in the blast furnace and measuring a change of the coke reactivity index according to the partial pressure of carbon dioxide, step; Supplying carbon dioxide and hydrogen together in the blast furnace under the reference carbon dioxide partial pressure, and measuring a change in the coke reactivity index according to the supplied hydrogen amount or hydrogen partial pressure; And evaluating coke reactivity from the deviation of the measured coke reactivity index and the reference coke reactivity index according to the supplied amount of hydrogen or hydrogen partial pressure.

In one embodiment, the unreactive gas may comprise nitrogen gas.

In another embodiment, the step of supplying the carbon dioxide and the unreactive gas together in the blast furnace may include diluting the hydrogen with the unreacted gas and injecting the unreactive gas.

In another embodiment, the ratio of hydrogen to unreacted gas may be from 1: 9 to 5: 5.

In another embodiment, the method may further include determining the quality of the coke to be provided at the time of introducing the hydrogen into the blast furnace, based on the evaluation result of the coke reactivity according to the supplied amount of hydrogen or the partial pressure of hydrogen.

According to the present invention, it is possible to easily obtain a method of measuring the coke reactivity, which increases with the amount of hydrogen to be injected, when performing the step of drawing hydrogen into the blast furnace.

FIG. 1 is a flowchart schematically showing a coke quality evaluation method according to an embodiment of the present invention.
FIG. 2 is a graph showing CRI * variation according to the flow rate of carbon dioxide injected into a blast furnace according to an embodiment of the present invention. FIG.
3 is a graph showing a change in CRI * according to the partial pressure of carbon dioxide in a blast furnace according to an embodiment of the present invention.
4 is a graph showing a change in CRI * according to an oxygen partial pressure in a blast furnace according to an embodiment of the present invention.
5 is a graph showing CRI * variation according to carbon monoxide partial pressure in a blast furnace according to an embodiment of the present invention.

Hereinafter, a method for evaluating coke quality according to an embodiment of the present invention will be described in detail. The terms used below are appropriately selected terms in consideration of functions in the present invention, and definitions of these terms should be made based on the contents throughout this specification.

It is expected that the reactivity of the coke will be changed by the hydrogen introduced when additional hydrogen is injected into the blast furnace. As described above, since the coke plays a role of providing adequate air permeability to the ironing property, for stable blast furnace operation, the coke needs to be managed to maintain the predetermined CSR.

Accordingly, in the case where the operation for injecting hydrogen is proceeded, the fluctuation of the reactivity of the coke depending on the amount of hydrogen to be injected is predicted in advance, and the quality of the coke to be introduced is controlled so that the coke can maintain the CSR even in the changed blast furnace operating environment Need to change.

  Conventionally, iron oxide is reacted with carbon monoxide (CO) in the blast furnace, and the reaction in which the iron ores are sequentially reduced and the carbon monoxide is oxidized is repeatedly carried out. As a result, the iron ore is converted into a molten iron and discharged to the bottom of the furnace, and the carbon monoxide is converted into carbon dioxide and discharged. Generally, it is known that carbon monoxide (CO) is produced by reacting pulverized coal provided in a blast furnace with oxygen to generate carbon dioxide (CO 2), and the carbon dioxide (CO 2) reacts with coke (C).

In an embodiment of the present invention, when hydrogen (H2) is further taken in, the hydrogen (H2) reacts with iron ores and is oxidized to generate water (H2O). Further, the water (H2O) reacts with the coke (C) to generate carbon monoxide (CO) and hydrogen (H2). The generated carbon monoxide (CO) and hydrogen (H2) may participate in the reduction reaction of the iron ore.

Thus, when hydrogen (H2) is introduced into the blast furnace, the reactivity index (CRI) of the coke can be changed by reacting the hydrogen (H2) with the coke. Because the Coke Reactivity Index (CRI) can change the CSR of the coke, it is necessary to monitor the change in the reactivity index of the coke for stable blast furnace operation.

FIG. 1 is a flowchart schematically showing a coke quality evaluation method according to an embodiment of the present invention. A coke having a predetermined coke reactivity index is injected into the blast furnace. Typically, when blast furnace operation is in progress, the coke can be controlled to maintain a CSR value of a predetermined value.

Referring to FIG. 1, in step S110, a reference coke reactivity index according to the carbon dioxide injection in the blast furnace is set.

According to a specific embodiment, only carbon dioxide is supplied to the interior of the blast furnace and changes in the Cokes reactivity index are measured as the amount of the supplied carbon dioxide increases. The supplied carbon dioxide may be generated by reacting oxygen with the pulverized coal as the oxygen is blown into the blast furnace.

As the amount of carbon dioxide supplied increases, the coke reactivity index may increase. When the supplied carbon dioxide reaches a predetermined amount, the coke reactivity index can be saturated. At this time, the saturated coke reactivity index can be set as a reference coke reactivity index. That is, in the carbon dioxide atmosphere above the predetermined amount, the coke can maintain the reference coke reactivity index.

Referring to step S120 of FIG. 1, carbon dioxide and unreactive gas are taken in and a reference carbon dioxide partial pressure condition corresponding to a reaction condition having the reference coke reactivity index is derived.

According to a specific embodiment, carbon dioxide and an unreactive gas are supplied together in the blast furnace. At this time, the partial pressure of the carbon dioxide may vary depending on the ratio of the carbon dioxide and the unreactive gas. In this step, the change of the coke reactivity index according to the change of the partial pressure of carbon dioxide is measured. At this time, the carbon dioxide partial pressure of the reaction condition having the same coke reactivity index as the reference coke reactivity index in step S110 is sought. The partial pressure of carbon dioxide in this reaction condition is derived from the reference partial pressure of carbon dioxide.

That is, when the unreacted gas and the carbon dioxide are introduced together, the coke injected into the blast furnace can maintain the reference coke reactivity index in the carbon dioxide atmosphere above the reference carbon dioxide partial pressure.

In one embodiment, the non-reactive gas may be nitrogen gas.

Referring to step S130 in FIG. 1, the coke reactivity index is measured according to the amount of hydrogen or partial pressure of hydrogen introduced under the reference carbon dioxide partial pressure.

According to a specific embodiment, under the reference carbon dioxide partial pressure, carbon dioxide and hydrogen are supplied together in the blast furnace. The partial pressure of the carbon dioxide may be increased with the reference carbon dioxide partial pressure being maintained constant according to the amount of the supplied hydrogen. In this step, under the reference carbon dioxide partial pressure, the change of the coke reactivity index with the increase of the amount of hydrogen supplied or the partial pressure of hydrogen is measured.

According to one embodiment, under the reference carbon dioxide partial pressure, as the hydrogen content or the hydrogen partial pressure increases, the coke reactivity index may increase. That is, by the introduced hydrogen, the coke can further react. Accordingly, the CSR of the coke during the blast furnace operation can be reduced.

Referring to step S140 in FIG. 1, the coke reactivity according to the amount of hydrogen injected or the hydrogen partial pressure is evaluated.

According to a specific embodiment, the deviation of the coke reactivity index and the reference coke reactivity index measured in step S130 is derived. From the deviation of the reactivity index, it is possible to evaluate the coke reactivity according to the supplied amount of hydrogen or the partial pressure of hydrogen. As an example, the hydrogen amount or the hydrogen partial pressure may be classified in stages, and the deviation may be graded in each step. Accordingly, the reduction amount of the coke CSR according to the increase amount of the hydrogen amount or the hydrogen partial pressure can be graded.

As a result, it is possible to inject a coke of a quality that compensates for the increase in the coke reactivity index, in view of the coke CSR which decreases with hydrogen input.

As in the following examples, in the case of a hydrogen atmosphere with a hydrogen partial pressure of 0.05, the CRI of the coke increased by 1.4 compared with the case where no hydrogen was added. Accordingly, in order to ensure stable operation, it is necessary to provide a new quality coke to the blast taking into consideration a CRI value increase of 1.4. Accordingly, the new quality coke changed in consideration of the increase in the CRI can maintain the same CSR as that of the conventional coke during the blast furnace operation.

Consequently, it is possible to determine the quality of the coke provided at the time of introducing the hydrogen into the blast furnace, based on the result of the evaluation of the coke reactivity according to the supplied amount of hydrogen or the hydrogen partial pressure obtained as a result of the steps S110 to S140 .

Example 1

Hereinafter, embodiments that can more clearly grasp the spirit of the present invention will be described.

As shown in Table 1, after injecting coke and iron ore with a CRI of 24.7% in the blast furnace, a gas composed of a combination of at least one of carbon dioxide, nitrogen, carbon monoxide, and hydrogen was blown into the blast furnace, . The CRI * values according to the conditions of Test Examples 1 to 11 were measured.

The coke CRI 24.7% standard corresponds to the CRI * of the coke measured when the blast furnace was operated under the conditions of Test Example 1. That is, CRI * indicates the reactivity index of the coke after the blast furnace operation.

unit Test Example 1 Test Example 2 Test Example 3 Test Example 4 Test Example 5 Test Example 6 Test Example 7 Test Example 8 Test Example 9 Test Example 10 Test Example 11 CO2 l / min 5 4 3 2 One 5 5 5 5 3 3 N2 l / min - - - - - 4.5 5 3.6 2.7 2.7 5 CO l / min - - - - - - - One 2 - - H2 l / min - - - - - 0.5 - 0.4 0.3 0.3 - pC02 ATM 1.0 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.5 0.38 pcO ATM pH2 ATM pO2 ATM 4.5 *
10 ^-5 4.5 *
10 ^-5 4.5 *
10 ^-5 4.5 *
10 ^-5 4.5 *
10 ^-5 2.8 *
10 ^-5 4.5 *
10 ^-5 8.9 *
10 ^-12 2.2 *
10 ^-12 1.1 *
10 ^-11 2.3 *
10 ^-5 CRI * % 24.7 24.7 24.5 24.6 18.4 26.1 24.6 24.1 20.6 25.5 20.2

Review

FIG. 2 is a graph showing CRI * variation according to the flow rate of carbon dioxide injected into a blast furnace according to an embodiment of the present invention. FIG. 2 shows the CRI * values according to the conditions of Test Examples 1 to 5 in Table 1.

As shown in FIG. 2, when the carbon dioxide flow rate is 2 l / min or more, the saturated CRI * is maintained at 24.7%, which means that stable operation is performed. That is, the reference coke reactivity index can be set to 24.7%.

On the other hand, the comparison between Test Example 7 and Test Example 11 indicates that the conditions of the carbon dioxide flow rate of 2 l / min are both the conditions, but when the nitrogen gas and the carbon dioxide gas are introduced together, the carbon dioxide partial pressure of Test Example 11 , The CRI * value was 20.2%, and the reactivity index decreased. At this time, the carbon dioxide partial pressure of 0.5 atm can be derived from the reference carbon dioxide partial pressure.

3 is a graph showing a change in CRI * according to the partial pressure of carbon dioxide in a blast furnace according to an embodiment of the present invention. 3 shows the CRI * values according to the conditions of Test Examples 1 to 3, Test Examples 6 to 8 and Test Example 11 in Table 1. [

Referring to FIG. 3 and Table 1, in Test Example 6, carbon dioxide and nitrogen gas were supplied at 5 l / min, respectively, and each partial pressure was 0.5 atm. At this time, the CRI * was measured as 24.6%, which is almost the same as the reference coke reactivity index. On the other hand, in Test Example 7, carbon dioxide, nitrogen gas and hydrogen gas were supplied at 5 l / min, 4.5 l / min, and 0.5 l / min, respectively, and the partial pressure of hydrogen was 0.05 atm. At this time, the measured CRI * increased to 26.1%.

Therefore, as compared with Test Example 6, the CRI * deviation 0.5% increased in Test Example 7 may correspond to a value increased by hydrogen gas injection.

4 is a graph showing a change in CRI * according to an oxygen partial pressure in a blast furnace according to an embodiment of the present invention. 4 shows the CRI * values according to the conditions of Test Example 1 and Test Examples 6 to 9 of Table 1.

Referring to FIG. 4, it can be shown that the inside of the blast furnace can maintain at least CRI * 24.1 when maintaining at least an oxygen partial pressure of 8.9 x 10 ^-12 atm.

5 is a graph showing CRI * variation according to carbon monoxide partial pressure in a blast furnace according to an embodiment of the present invention. 5 shows the CRI * values according to the conditions of Test Examples 7 to 9 in Table 1. [

Referring to FIG. 5, providing carbon monoxide in the blast furnace indicates a decrease in CRI * value. It is considered that the carbon monoxide supplied from the outside reduces the oxygen partial pressure.

Example 2

And the effect of reducing the carbon dioxide by introducing hydrogen gas into the blast furnace was evaluated. First, 1650 kg / THM of iron ore and 340 kg / THM of coke were put into the upper part of the blast furnace, and 160 kg / THM of pulverized coal was poured into a blast furnace under the condition of oxygen enrichment amount of 56 Nm ³ / THM and air volume of 840 NNm ³ / THM Respectively. As a result, the blast furnace production was maintained at 12,000 tons / day and blast furnace operation was continued. At this time, the gas discharged via the top outlet of the furnace is 1468.6 Nm ³ / THM was, the composition of the exhaust gas is carbon monoxide (CO) 352.5 Nm3 / THM, carbon dioxide ^{(CO2) 352.5 Nm 3 / THM} , nitrogen (N2) 719.6 Nm ³ / THM, and hydrogen 44.1 Nm ³ / THM.

In one embodiment, 1650 kg / THM of iron ore and 302.2 kg / THM of coke were charged into the upper part of the blast furnace, and 160 kg / THM of pulverized coal was passed through a blast furnace at an oxygen enrichment rate of 68.0 Nm ³ / THM and an air flow rate of 666.9 NNm ³ / Respectively. At the same time, 173.1 Nm ³ / THM of hydrogen gas was blown through the tug. As a result, the blast furnace production was maintained at 12,000 tons / day and blast furnace operation was continued. At this time, the gas discharged via the top outlet of the furnace is 1463.0 Nm ³ / THM was, the composition of the exhaust gas is carbon monoxide (CO) 311.7 Nm3 / THM, carbon dioxide ^{(CO2) 311.7 Nm 3 / THM} , nitrogen (N2) 653.9 Nm ³ / THM, and hydrogen of 69.1 Nm ³ / THM.

At this time, the ratio of hydrogen to carbon dioxide taken in the blast furnace in the embodiment was controlled to 3:10, and it was confirmed that the amount of carbon dioxide discharged was about 10% lower than that of the comparative example. That is, it is possible to suppress the emission of about 10% of carbon dioxide at the same amount of production of charcoal by injecting hydrogen.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It can be understood that

10: molten steel, 20: air, 30: interface,
110: nitrogen, 120: sulfur, 210: nitrogen gas.

Claims (6)

(a) supplying only carbon dioxide into the blast furnace and measuring a change in the coke reactivity index as the amount of carbon dioxide supplied increases; setting the saturated coke reactivity index to a reference coke reactivity index when the coke reactivity index is saturated;
(b) supplying carbon dioxide and an unreactive gas together in the blast furnace, measuring a change in the coke reactivity index according to the partial pressure of the carbon dioxide, wherein the partial pressure of the carbon dioxide in the reaction condition having the same coke reactivity index as the reference coke reactivity index, Deriving by partial pressure;
(c) supplying carbon dioxide and hydrogen together in the blast furnace under the reference carbon dioxide partial pressure, and measuring a change in the coke reactivity index according to the supplied hydrogen amount or hydrogen partial pressure; And
(d) evaluating coke reactivity from the deviation of the coke reactivity index and the reference coke reactivity index measured in the step (c) according to the supplied amount of hydrogen or hydrogen partial pressure
A Method for Evaluating the Quality of Coke by Addition of Hydrogen in Blast Furnace.
The method according to claim 1,
wherein said unreactive gas in step (b) comprises nitrogen gas
A Method for Evaluating the Quality of Coke by Addition of Hydrogen in Blast Furnace.
The method according to claim 1,
(c)
The hydrogen is diluted with an unreacted gas and then introduced
A Method for Evaluating the Quality of Coke by Addition of Hydrogen in Blast Furnace.
The method of claim 3,
The volume ratio of the hydrogen and the unreactive gas is 1: 9 to 5: 5
A Method for Evaluating the Quality of Coke by Addition of Hydrogen in Blast Furnace.
5. The method of claim 4,
Wherein the unreactive gas comprises nitrogen gas
A Method for Evaluating the Quality of Coke by Addition of Hydrogen in Blast Furnace.
The method according to claim 1,
Further comprising the step of determining the quality of the coke to be provided at the time of introducing the hydrogen into the blast furnace, based on the result of the evaluation of the coke reactivity according to the supplied amount of hydrogen or the partial pressure of hydrogen
A Method for Evaluating the Quality of Coke by Addition of Hydrogen in Blast Furnace.

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