JP2010202713A - Method for manufacturing highly reactive molded ferrocoke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing highly reactive coke to be introduced to lower the heat preservation zone temperature in a blast furnace up to a target temperature. <P>SOLUTION: The method for manufacturing highly reactive coke to be introduced to lower the heat preservation zone temperature in a blast furnace up to a target temperature comprises (a) measuring a gasification reaction initiation temperature of the coke whose reactivity is modified by changing the Fe content of the coke and the heat preservation zone temperature under a predetermined heat-up condition to obtain the relationship (a1) between the Fe content of the coke and the gasification reaction initiation temperature and the correlation (a2) between the gasification reaction initiation temperature of the coke and the heat preservation zone temperature, (b) obtaining the gasification reaction initiation temperature that the coke to be introduced into the blast furnace should possess on the basis of the target temperature and the correlation (a2), (c) obtaining the Fe content of the coke to be introduced into the blast furnace on the basis of the gasification reaction initiation temperature and the relationship (a1), and (d) compounding Fe with raw material coal on the basis of the Fe content to manufacture coke. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing molded ferrocoke having excellent reactivity.

In the blast furnace ironmaking method, increasing the reaction efficiency in the blast furnace and reducing the reducing material ratio are important in promoting energy saving. As a method for that purpose, (i) CO ₂ gas of coke It is known to increase the gasification reactivity, or (ii) lower the reaction start temperature, thereby lowering the temperature of the heat preservation zone and proceeding gas reduction advantageously (see Patent Documents 1 to 4). .

In a furnace in which atmospheric conditions (CO concentration, CO ₂ concentration) are limited to some extent, as a method for increasing the CO ₂ gasification reactivity of coke, in addition to a method of making coke fine, a catalyst material ( There is known a method in which an alkali metal, an alkaline earth metal compound, a transition metal, a transition metal compound, etc.) are mixed and subjected to dry distillation (see Patent Documents 5 to 9). However, in the conventional method, it is difficult to obtain a sufficient coke strength.

And in a furnace where the atmospheric conditions (CO concentration, CO ₂ concentration) are limited to some extent, in order to lower the storage zone temperature and proceed with gas reduction advantageously, the reactivity of the highly reactive coke Until now, it has not been quantitatively analyzed how much blending amount should be used.

  That is, since the degree of reduction of the reducing material ratio is substantially proportional to the degree of reduction of the heat storage zone temperature, in order to reduce the reducing material ratio by the target, it is necessary to reduce the temperature of the heat preservation zone by an amount corresponding to the target. Somehow, it has not been quantitatively analyzed so far how much the high-reactivity coke having a high degree of reactivity will reduce the temperature of the thermal preservation zone. .

  Regarding the degree of decrease in the temperature of the heat preservation zone, for example, there is a method of evaluating with a BIS furnace (adiabatic blast furnace reaction simulator, see Non-Patent Document 1), but the test with the BIS furnace is an experiment preparation, an experiment, and Since time (about 3 days) is required for the experimental analysis, the analysis result is not easily reflected in the operation control promptly. Therefore, (i) an evaluation method for quantitatively evaluating fluctuations in the temperature of the heat preservation zone when the reactivity of the highly reactive coke is changed, and (ii) the temperature of the heat preservation zone in the blast furnace is reduced to the target temperature. There is a need for the development of a process for producing highly reactive coke that is charged to lower.

Japanese Patent Laid-Open No. 06-145728 Japanese Patent Laid-Open No. 06-145729 Japanese Patent Laid-Open No. 06-145730 Japanese Patent Laid-Open No. 06-145734 Japanese Unexamined Patent Publication No. 63-137989 JP 2001-348576 A JP 2004-300170 A JP 2008-56791 A JP 2007-126505 A

Naito et al., Iron and Steel, 87 (2001), page 357

  As a result of intensive studies based on the above request (i), the present inventors have found that “a clear correlation between the reaction start temperature measured by the small reaction gasification test apparatus and the thermal preservation zone temperature measured by the BIS furnace”. With the knowledge that there is a relationship ”, the reactivity of highly reactive coke is changed when using highly reactive coke containing a catalyst for improving reactivity such as Fe and Ca in normal coke. Japanese Patent Application No. 2009-046060 proposed an evaluation method for evaluating fluctuations in the temperature of the heat preservation zone when the reactivity improving catalyst was added (ie, by changing the addition amount of the reactivity improving catalyst).

  The present invention further provides a method for producing a highly reactive coke to be charged in order to lower the heat preservation zone temperature in the blast furnace to the target temperature based on the above request (ii). Let it be an issue.

  The present inventors diligently studied a method for solving the above-described problems. As a result, it was found that the target heat storage zone temperature can be achieved in the blast furnace by charging the highly reactive coke produced by setting the catalyst blending amount based on the above knowledge.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

  (1) A method for producing highly reactive coke charged to lower the temperature of the heat preservation zone in the blast furnace to the target temperature, and (a) gasification of coke whose reactivity is changed by changing the Fe content The reaction start temperature and the thermal storage zone temperature were measured under a constant temperature rise condition, (a1) the relationship between the Fe content of coke and the gasification reaction start temperature, and (a2) the gasification reaction start temperature and heat of the coke. Obtain the correlation between the storage zone temperatures, (b) obtain the gasification reaction start temperature that the coke charged into the blast furnace should have based on the correlation between the target temperature and (a2), and (c) the gas The Fe content of coke charged into the blast furnace is obtained based on the relationship between the chemical reaction start temperature and the above (a1), and (d) Fe is blended into the raw coal based on the Fe content. A method for producing highly reactive coke, characterized in that coke is produced.

  (2) The method for producing highly reactive coke according to (1), wherein the highly reactive coke is formed coke.

  (3) The method for producing highly reactive coke according to (1) or (2), wherein the gasification reaction start temperature of the coke is obtained with a small reaction gasification test apparatus.

  (4) The correlation of the above (a2) is obtained based on the coke gasification reaction start temperature measured with a small reaction gasification test apparatus and the heat preservation zone temperature measured with a BIS furnace. The method for producing highly reactive coke according to any one of (1) to (3).

  (5) Production of highly reactive coke according to (4) above, wherein in the correlation of (a1), the gasification reaction start temperature of coke is substantially equal to the heat storage zone temperature measured in a BIS furnace Method.

  ADVANTAGE OF THE INVENTION According to this invention, the highly reactive coke which can achieve the target heat preservation zone temperature can be manufactured within a blast furnace.

It is a figure which shows the one aspect | mode of a small reaction gasification test apparatus. It is a figure which shows the aspect of a BIS furnace. It is a figure which shows the relationship between Fe content rate (%) of coke, and gasification reaction start temperature (degreeC). It is a figure which shows the correlation of gasification reaction start temperature and thermal preservation zone temperature. It is a figure which shows the relationship between the Fe content rate of the coke confirmed in the Example, and gasification reaction start temperature. It is a figure which shows the correlation of the gasification reaction start temperature of the coke confirmed in the Example, and the thermal preservation zone temperature measured with the BIS furnace.

  The present invention will be described in detail.

  The basic idea of the present invention is to produce a highly reactive coke to be charged in order to lower the temperature of the heat preservation zone in the blast furnace to the target temperature, and the coke gasification reaction in which the reactivity is changed by changing the Fe content. (A1) Relationship between coke coke Fe content and gasification reaction start temperature, and (a2) coke gasification reaction start temperature, obtained by measuring the start temperature and thermal storage zone temperature under a constant temperature rise condition And the correlation between the temperature of the heat preservation zone and the temperature.

  First, the relationship between the Fe content of coke and the gasification reaction start temperature (hereinafter sometimes referred to as “relation (a1)”) will be described.

  The highly reactive coke may be either normal (non-molded) coke (corresponding to chamber furnace coke) or molded coke. The reactivity of the highly reactive coke is adjusted by changing the Fe content of the raw coal. Fe in the coke acts as a catalyst, increases the gasification reactivity of the coke, and lowers the heat storage zone temperature in the blast furnace. The dry distillation conditions may be normal dry distillation conditions.

  FIG. 1 shows an embodiment of a small reactive gasification test apparatus that measures the gasification reaction start temperature of highly reactive coke. Note that this apparatus is basically the same as the apparatus for measuring the post-hot-reaction powder rate of coke disclosed in JP-A-2007-309672.

  In the small reaction gasification test apparatus shown in FIG. 1, a reaction inner tube 3 having a gas supply port 7 in the upper portion and a heating means 2 in the periphery is disposed inside the reaction outer tube 1. The bottom of the reaction inner tube 3 is filled with alumina spheres 4 on which coke 5 is charged.

After closing the reaction inner tube 3 with a tube lid 6 having a gas discharge port 8 and a thermometer 9, a reaction gas (CO + CO ₂ ) is supplied from the gas supply port 7 at a flow rate of 15 to 25 Nl / min (preferably 20 Nl / min). min), and the gas after reaction is discharged from the gas discharge port 8. The reaction gas is preheated while entering the bottom of the reaction tube from the upper supply port 7 and passing through the alumina sphere.

Here, the ratio of CO to CO ₂ is preferably CO: CO ₂ = 50%: 50%, but it may be a gas composition close to the composition of the shaft portion at the top of the blast furnace, CO: 70% to 30%, CO ₂ : It may be 30% to 70%.

  The small reaction gasification test apparatus is equipped with a weight measuring device (not shown). While the gasification reaction is in progress, the thermometer 9 measures the coke temperature and the coke weight.

  In the experiment, the temperature is increased from room temperature at a predetermined temperature increase rate (for example, 10 ° C./min), and the weight loss of coke is measured.

The coke gasification reaction consumes coke and the weight of the coke decreases, so the weight reduction rate of coke per unit time: (1 / w ₀ ) × (dw / dt) (where t is the time [Min], w is the coke weight [g] at time t, w ₀ is the temperature at which the initial coke weight [g]) exceeds 0.002 (min ⁻¹ ), and the coke reaction start temperature. taking measurement.

In this measurement, since the rate of temperature increase is constant, when the coke weight at the temperature T (° C.) is w, the weight reduction rate of the coke per unit temperature rise: (1 / w ₀ ) × (dw / The temperature at which dT) exceeds 0.0002 (° C. ⁻¹ ) may be measured as the reaction start temperature of coke.

  Thus, when the reaction start temperature of coke is defined, the temperature increase rate may be changed and the reaction start temperature of coke may be measured at a constant temperature increase rate. If it is the range of a temperature increase rate (5-20 degreeC / min), it is possible to measure the reaction start temperature of coke by this method.

  FIG. 3 shows the relationship between the Fe content (%) in coke and the gasification reaction start temperature of coke measured for coke containing Fe as a catalyst. In FIG. 3, ◯ is a measured value related to molded coke, and □ is a measured value related to normal (not molded) coke.

  From FIG. 3, it can be seen that, for example, the gasification reaction start temperature (° C.) of coke (see ◯) decreases linearly as the Fe content in the coke increases. When the Fe content in the coke is 10%, the coke gasification reaction start temperature (° C.) is 1050 ° C., but the coke in the coke gasification reaction start temperature (° C.) is 45%. Decreases to 950 ° C.

  Thus, the gasification reaction start temperature of coke decreases linearly as the Fe content increases. In the present invention, as described above, it is important to determine the relationship (a1) between the Fe content of coke and the gasification reaction start temperature, and this relationship (a1) is one of the basic features of the present invention. .

  Next, the correlation between the thermal storage zone temperature and the coke gasification reaction start temperature measured with a small reaction gasification test apparatus (hereinafter, also referred to as “correlation (a2)”) will be described. This correlation (a2) is the knowledge that the present inventors have found and forms the basis of the present invention, and is one of the basic features of the present invention.

  The heat preservation zone temperature is measured with a BIS furnace shown in FIG. In the BIS furnace, an iron furnace (sintered ore) 11 and coke 12 are alternately packed in layers in a reaction tube 10 and placed on the outer periphery of the reaction tube 10 (a heating furnace 15 and a heat insulation furnace 16). The reaction gas is introduced from the gas inlet 14 at the top of the reaction tube 10, and a plurality of iron ore (sintered) 11 layers, and This is a counter-current moving bed type reaction test device that passes through the coke 12 layer and discharges it from the gas discharge port 17 at the bottom of the reaction tube 10.

  The reaction tube 10 is a stainless steel tube having an inner diameter of 103 mm and a length of 5.4 m. The electric furnace 13 includes a heating furnace 15 for preheating the reaction gas to the upper temperature of the blast furnace fusion zone (1200 ° C.) and terminating the ore reduction, and an adiabatic furnace 16 for causing the reaction below this temperature to proceed in an adiabatic system. It consists of The heating furnace 15 and the heat insulation furnace 16 have lengths of 950 mm and 1090 mm, respectively.

  Since it takes a long time (about 3 days) to measure the temperature of the heat preservation zone by the BIS furnace, it is difficult to quickly reflect the fluctuation of the temperature of the heat preservation zone in the actual blast furnace in the operation control. The inventors have found that the gasification reaction start temperature of coke, which can be easily measured with a small reaction gasification test apparatus, and the fluctuation thereof are in good agreement with the temperature of the thermal preservation zone measured in a BIS furnace and the fluctuation thereof.

  FIG. 4 shows the correlation between the coke gasification reaction start temperature arranged by the Fe content in the coke and the thermal storage zone temperature measured in the BIS furnace. In the figure, ○ indicates the case of normal (not formed) coke, and □ indicates the case of formed coke. It can be seen from FIG. 4 that the coke gasification reaction start temperature and the thermal preservation zone temperature measured in the BIS furnace have a substantially one-to-one correspondence regardless of the coke form.

  That is, according to the correlation (a2), the heat preservation measured in the BIS furnace can be obtained by measuring the gasification reaction start temperature of coke with a small reaction gasification test device without measuring the heat preservation zone temperature. It is possible to know the belt temperature and its fluctuation. As a result, when the temperature of the heat preservation zone in the blast furnace is to be lowered to the target temperature, the gasification reaction start temperature that the highly reactive coke charged into the blast furnace should have can be obtained.

  If the gasification reaction start temperature to be provided for the highly reactive coke charged into the blast furnace is obtained, the Fe content of the coke charged into the blast furnace can be obtained based on the relationship (a1). If the Fe content of coke charged into the blast furnace is obtained, highly reactive coke can be produced by blending Fe with raw coal based on the content.

  Next, examples of the present invention will be described. The conditions of the examples are one example of conditions adopted for confirming the feasibility and effects of the present invention, and the present invention is limited to this one example of conditions. Is not to be done. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

Example 1
Coke was produced by dry distillation of blended coal containing 50% each of A and B coals having the properties shown in Table 1, and the gasification reaction start temperature of the coke was measured with a small reaction gasification test apparatus shown in FIG. . The results are shown in Table 2. Moreover, about some cokes, the heat preservation zone temperature was measured with the BIS furnace shown in FIG. The results are also shown in Table 2.

  FIG. 5 shows the relationship between the Fe content of coke and the gasification reaction start temperature of coke. The coke gasification reaction start temperature decreases linearly as the Fe content increases.

  FIG. 6 shows a correlation between the coke gasification reaction start temperature and the thermal preservation zone temperature measured in a BIS furnace. There is a very good correspondence between the gasification reaction start temperature of coke and the heat preservation zone temperature measured by the BIS furnace.

(Example 2)
The target of the heat preservation zone temperature in the blast furnace was set to 980 ° C., and the gasification reaction start temperature of coke: 980 ° C. was determined based on the correlation (a2) shown in FIG. Next, from the coke gasification reaction start temperature: 980 ° C., the Fe content in the highly reactive ferro-coke: 30% was determined based on the relationship (a1) shown in FIG.

  According to this Fe content, Fe was added to the raw coal to produce highly reactive coke and charged into the blast furnace. When the temperature of the heat preservation zone in the blast furnace was measured, it was 982 ° C., which was almost the same as the target temperature: 980 ° C.

  As described above, according to the present invention, a highly reactive coke capable of achieving a target heat preservation zone temperature can be produced in a blast furnace. Therefore, the present invention has high applicability in the steel industry.

1 reaction outer tube 2 heating means 3 reaction inner tube 4 alumina bulb 5 coke 6 tube lid 7 gas supply port 8 gas discharge port 9 thermometer 10 reaction tube 11 iron ore (sintered ore)
12 Coke 13 Electric furnace 14 Gas inlet 15 Heating furnace 16 Heat insulation furnace 17 Gas outlet

Claims (5)

A method for producing a highly reactive coke charged to lower the temperature of the heat preservation zone in the blast furnace to a target temperature,
(A) The gasification reaction start temperature and heat storage zone temperature of coke whose reactivity was changed by changing the Fe content were measured under a constant temperature rise condition,
(a1) relationship between coke Fe content and gasification reaction start temperature, and
(a2) Obtain the correlation between the gasification reaction start temperature of coke and the temperature of the thermal preservation zone,
(B) Based on the correlation between the target temperature and the above (a2), obtain the gasification reaction start temperature that the coke charged into the blast furnace should have,
(C) Based on the gasification reaction start temperature and the relationship of (a1), the Fe content of coke charged into the blast furnace is obtained,
(D) A method for producing highly reactive coke, wherein coke is produced by blending Fe into raw coal based on the Fe content.   The method for producing highly reactive coke according to claim 1, wherein the highly reactive coke is formed coke.   The method for producing a highly reactive coke according to claim 1 or 2, wherein a gasification reaction start temperature of the coke is obtained with a small reactive gasification test apparatus.   The correlation of (a2) is obtained on the basis of the gasification reaction start temperature of coke measured with a small reaction gasification test apparatus and the heat storage zone temperature measured with a BIS furnace. Item 4. The method for producing a highly reactive coke according to any one of Items 1 to 3.   5. The method for producing highly reactive coke according to claim 4, wherein, in the correlation (a1), the gasification reaction start temperature of coke is substantially equal to the heat storage zone temperature measured in a BIS furnace.

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