JPWO2014020965A1 - Blast furnace blown coal and method for producing the same - Google Patents

Abstract

A blast furnace-blown coal that is blown into a blast furnace main body of a blast furnace facility, having an oxygen atom content ratio (dry base) of 10 to 20% by weight and an average pore diameter of 10 to 50 nm.

Description

  The present invention relates to blast furnace blown coal and a method for producing the same.

  In the blast furnace facility, raw materials such as iron ore, limestone, and coke are charged into the blast furnace body from the top, and hot air and pulverized coal (PCI charcoal) as auxiliary fuel are blown from the tuyere near the side. Thus, pig iron can be produced from iron ore.

As such a blast furnace injection coal, for example, by adding an oxidizing agent such as KMnO ₄ , H ₂ O ₂ , KClO ₃ , K ₂ Cr ₂ O ₄ to pulverized coal in advance, combustion efficiency is improved. In order to suppress the generation of unburned carbon (soot), there has been proposed (for example, see Patent Document 1 below).

  Further, for example, it has been proposed to improve the combustibility of blast furnace-blown coal by enriching hot air with oxygen and blowing it into the blast furnace body from the tuyere (see, for example, Patent Document 2 below). ).

JP-A-6-220510 JP 2003-286511 A

  However, since the blast furnace injection coal described in the above-mentioned Patent Document 1 purposely adds the oxidant as described above to the pulverized coal, the running cost is increased.

  Further, in the method for improving combustibility described in Patent Document 2, since it is necessary to operate the blast furnace while constantly adding a large amount of oxygen to the hot air, the running cost is also increased.

  In view of the above, an object of the present invention is to provide a blast furnace blown coal capable of improving combustion efficiency at a low cost and suppressing generation of unburned carbon (soot) and a method for producing the same.

  The blast furnace injection coal according to the first invention for solving the above-mentioned problem is blast furnace injection coal injected from the tuyere into the blast furnace main body of the blast furnace equipment, and has an oxygen atom content ratio (dry base). Is 10 to 20% by weight, and the average pore diameter is 10 to 50 nm.

The blast furnace blown coal according to the second invention is characterized in that, in the first invention, the pore volume is 0.05 to 0.5 cm ³ / g.

The blast furnace blown coal according to the third invention is characterized in that, in the first or second invention, the specific surface area is 1 to 100 m ² / g.

  A method for producing blast furnace blown coal according to the fourth aspect of the invention for solving the above-described problem is a method for producing blast furnace blown coal according to any one of the first to third aspects of the invention. A drying process for heating sub-bituminous coal or lignite to remove moisture and a carbonization process for carbonizing the charcoal dried in the drying process at 460 to 590 ° C. are performed.

  According to a fifth aspect of the present invention, there is provided a method for producing blast furnace-blown charcoal in the fourth aspect, wherein the charcoal dry-distilled in the dry distillation step is cooled to 50 to 150 ° C. and cooled in the cooling step. The charcoal is exposed to an oxygen-containing atmosphere at 50 to 150 ° C. to perform a partial oxidation step in which oxygen is chemically adsorbed and partially oxidized.

  According to the blast furnace blown coal according to the present invention, the average pore diameter is 10 to 50 nm, that is, tar-generating groups such as oxygen-containing functional groups (carboxyl group, aldehyde group, ester group, hydroxyl group, etc.) are eliminated. Although it is greatly reduced, the oxygen atom content (dry base) is 10 to 20% by weight, that is, the decomposition (reduction) of the main skeleton (combustion components centering on C, H, O) is greatly suppressed. Therefore, when blowing with hot air from the tuyere into the inside of the blast furnace body, it contains not only oxygen atoms in the main skeleton, but also oxygen in the hot air is easily diffused into the interior by the large diameter pores. Because it is very difficult to generate a minute, it can be burned completely with almost no unburned carbon (soot), improving combustion efficiency at low cost and suppressing the generation of unburned carbon (soot). Rukoto can.

  Moreover, according to the manufacturing method of the blast furnace injection coal which concerns on this invention, the blast furnace injection coal mentioned above can be manufactured at low cost.

It is a flowchart showing the procedure of 1st embodiment of the manufacturing method of the blast furnace injection charcoal which concerns on this invention. It is a flowchart showing the procedure of 2nd embodiment of the manufacturing method of the blast furnace injection charcoal which concerns on this invention. It is a graph showing the relationship between temperature and the content rate of an oxygen-containing functional group when an infrared absorption spectrum is measured, heating sub-bituminous coal in nitrogen atmosphere. It is a graph showing the relationship between the ratio of the unburned carbon collect | recovered after burning this invention charcoal, dry charcoal, and conventional charcoal, and the residual oxygen concentration (excess oxygen concentration) in the combustion exhaust gas after burning. It is a graph showing the relationship between excess oxygen rate and combustion temperature when this invention charcoal and conventional charcoal are completely burned.

  Embodiments of blast furnace blown coal and a method for producing the same according to the present invention will be described with reference to the drawings. However, the present invention is not limited to only the following embodiments described with reference to the drawings.

<First embodiment>
A first embodiment of a blast furnace blown coal and a method for producing the same according to the present invention will be described with reference to FIG.

  The blast furnace-blown coal according to this embodiment has an oxygen atom content (dry base) of 10 to 18% by weight and an average pore size of 10 to 50 nm (nanometer) (preferably 20 to 50 nm (nanometer). ).

  As shown in FIG. 1, the blast furnace blown coal according to this embodiment is a low-grade coal such as subbituminous coal or lignite (oxygen atom content ratio (dry base): more than 18% by weight, average pore diameter: 3 After removing water by heating (110 to 200 ° C. × 0.5 to 1 hour) in a low oxygen atmosphere (oxygen concentration: 5% by volume or less) 11 and drying (drying step S11), Generated by heating (460-590 ° C. (preferably, 500-550 ° C.) × 0.5-1 hour) in a low oxygen atmosphere (oxygen concentration: 2% by volume or less) and dry distillation (dry distillation step S12) Water, carbon dioxide, tar content, etc. are removed as dry distillation gas or dry distillation oil, then cooled (50 ° C. or lower) in a low oxygen atmosphere (oxygen concentration: 2% by volume or lower) (cooling step S13), and pulverized (Particle size: 77 μm or less (80% pass)) The step S14) it can be easily manufactured.

  In the blast furnace blown coal 12 manufactured by such a manufacturing method according to this embodiment, the average pore diameter is 10 to 50 nm, that is, oxygen-containing functional groups (carboxyl group, aldehyde group, ester group, hydroxyl group, etc. ) And other tar-generating groups are greatly reduced, but the oxygen atom content (dry base) is 10 to 18% by weight, that is, a combustion component centered on the main skeleton (C, H, O) ) Is greatly suppressed, and when hot air is blown into the blast furnace body together with hot air from the tuyere, the main skeleton contains a large amount of oxygen atoms, and the oxygen in the hot air is contained inside by the large-diameter pores. In addition to being easily diffused, the tar content is very difficult to generate, so that it is possible to complete combustion with almost no unburned carbon (soot).

Therefore, the blast furnace blowing coal 12 according to the present _{embodiment, KMnO 4, H 2 O 2} , KClO 3, K 2 and be contained Cr oxidizing agent such as ₂ O _4, so as to enrich the oxygen in a hot-air Even if nothing is done, the combustion efficiency can be improved and the generation of unburned carbon (soot) can be suppressed.

  Therefore, according to the present embodiment, it is possible to improve the combustion efficiency at a low cost and suppress the generation of unburned carbon (soot).

  In addition, in the blast furnace injection charcoal 12 which concerns on this embodiment, an average pore diameter needs to be 10-50 nm (preferably 20-50 nm). Because if it is less than 10 nm, the ease of diffusion of oxygen in the hot air will decrease, causing a decrease in combustibility, while if it exceeds 50 nm, it tends to crack and become fine due to heat shock or the like. This is because, when blown into the blast furnace body, if it breaks and becomes fine, it passes through the inside of the blast furnace body while riding on a gas stream and is discharged without burning.

  Further, the oxygen atom content (dry base) needs to be 10% by weight or more. This is because if it is less than 10% by weight, it becomes difficult to completely burn without containing an oxidant and enriching hot air with oxygen.

Further, the pore volume is preferable to be 0.05~0.5cm ³ / g, is highly preferred in particular is 0.1~0.2cm ³ / g. Because, if it is less than 0.05 cm ³ / g, the contact area with oxygen in the hot air (reaction area) is small, which may cause a decrease in combustibility, whereas if it exceeds 0.5 cm ³ / g, This is because the volatilization of many components results in excessively porous components due to being too porous.

In addition, the specific surface area is, preferable to be 1 to 100 m ² / g, highly preferred in particular is 5 to 20 m ² / g. Because if it is less than 1 m ² / g, the contact area (reaction area) with oxygen in the hot air is small, which may cause a decrease in combustibility, while if it exceeds 100 m ² / g, many components This is because the volatilization of the fuel is too porous and the combustion components become too small.

  On the other hand, in the method for producing blast furnace blown coal according to the present embodiment, the dry distillation temperature in the dry distillation step S12 needs to be 460 to 590 ° C (preferably 500 to 550 ° C). This is because if the temperature is lower than 460 ° C., the tar-forming groups such as oxygen-containing functional groups cannot be sufficiently removed from the low-grade coal 11 and it is very difficult to set the average pore diameter to 10 to 50 nm. On the other hand, when the temperature exceeds 590 ° C., decomposition of the main skeleton of the low-grade coal 11 (combustion components centering on C, H, O) starts to become remarkable, and the combustion components decrease due to volatilization of many components. This is because too much is done.

<Second Embodiment>
A second embodiment of the blast furnace blown coal and the method for producing the same according to the present invention will be described with reference to FIG. In addition, about the part similar to the case of embodiment mentioned above, the description and duplication description in embodiment mentioned above are abbreviate | omitted by using the code | symbol similar to the code | symbol used in description of embodiment mentioned above.

  The blast furnace blown coal according to the present embodiment has an oxygen atom content (dry base) of 12 to 20% by weight and an average pore diameter of 10 to 50 nm (preferably 20 to 50 nm).

  As shown in FIG. 2, the blast furnace injection coal according to this embodiment is the same as the above-described embodiment in which the low-grade coal (oxygen atom content ratio (dry base): more than 18 wt%) 11 is used. Dry (drying step S11), dry-distill in the same manner as the above-described embodiment (dry-distilling step S12), and cool (50 to 150 ° C.) in a low oxygen atmosphere (oxygen concentration: 2% by volume or less) (cooling) Step S23) After oxygen is chemically adsorbed and partially oxidized by exposure to oxygen-containing atmosphere (oxygen concentration: 5 to 21% by volume) (50 to 150 ° C. × 0.5 to 10 hours) (partial oxidation) Step S25) can be easily manufactured by finely pulverizing in the same manner as the above-described embodiment (fine pulverization step S14).

  That is, in this embodiment, after the charcoal carbonized in the carbonization step S12 is cooled to 50 to 150 ° C., oxygen is chemically adsorbed to the charcoal in the partial oxidation step S25 to partially oxidize the charcoal. Thus, the blast furnace-blown coal 22 having an oxygen atom content ratio (dry base) of 12 to 20% by weight was obtained.

  In the blast furnace blown coal 22 manufactured by such a manufacturing method according to this embodiment, the average pore diameter is 10 to 50 nm, that is, the oxygen-containing functional group (carboxyl) as in the case of the above-described embodiment. Although a tar-forming group such as a group, an aldehyde group, an ester group or a hydroxyl group is eliminated and greatly reduced, the oxygen atom content (dry base) is 12 to 20% by weight, that is, the main skeleton (C The decomposition (decrease) of the combustion components, mainly H, O, and O) is greatly suppressed, and oxygen atoms are further chemically adsorbed. The main skeleton contains more oxygen atoms than in the case of the embodiment, and as in the case of the above-described embodiment, the hot air oxygen is easily diffused into the inside by the large-diameter pores. Not only because tar is less likely very occur, it is possible to complete combustion without causing additional unburned carbon (soot) than in the embodiments described above.

Therefore, the blast furnace blowing coal 22 according to the present _{embodiment, KMnO 4, H 2 O 2} , KClO 3, K 2 and be contained Cr oxidizing agent such as ₂ O _4, so as to enrich the oxygen in a hot-air Even if nothing is done, the combustion efficiency can be further improved and the generation of unburned carbon (soot) can be more reliably suppressed than in the above-described embodiment.

  Therefore, according to the present embodiment, it is possible to further reliably suppress the generation of unburned carbon (soot) by improving the combustion efficiency at a lower cost than in the case of the above-described embodiment.

  In the blast furnace blown coal 22 according to this embodiment, the oxygen atom content ratio (dry base) needs to be 20% by weight or less. This is because if it exceeds 20% by weight, the oxygen content is too high and the calorific value becomes too low.

  On the other hand, in the method for producing blast furnace blown coal according to the present embodiment, the treatment temperature of the partial oxidation step S25 is preferably 50 to 150 ° C. This is because, if the temperature is less than 50 ° C., even in an air (oxygen concentration: 21% by volume) atmosphere, the partial oxidation treatment is difficult to proceed. If the temperature exceeds 150 ° C., the oxygen concentration is about 5% by volume. Even so, there is a possibility that a large amount of carbon monoxide and carbon dioxide may be generated by the combustion reaction.

  Examples carried out for confirming the effects of the blast furnace blow coal and the method for producing the same according to the present invention will be described below, but the present invention is limited only to the following examples described based on various data. It is not something.

<No. 1: Composition analysis>
Composition analysis (elemental analysis) of the blast furnace blown coal 12 (present coal) obtained by the manufacturing method according to the first embodiment described above was performed. For comparison, a composition analysis of conventional blast furnace blown coal (PCI coal: conventional coal) and coal obtained by omitting the carbonization step S12 in the first embodiment (dry coal) is also performed. I went. The results are shown in Table 1 below. All values are on a dry basis.

  As can be seen from Table 1 above, the coal of the present invention has a proportion of oxygen (O) smaller than that of dry coal and is much larger than that of conventional coal, while a proportion of carbon (C) is larger than that of dry coal. It is smaller than conventional charcoal. For this reason, the coal of the present invention has a calorific value larger than that of dry coal and smaller than that of conventional coal.

<No. 2: Surface condition>
The surface state (average pore diameter, pore volume, specific surface area) of the above-described coal of the present invention was measured. For comparison, the surface states of the above-described conventional charcoal and dry charcoal were also measured. The results are shown in Table 2 below.

  As can be seen from Table 2 above, the coal of the present invention has an average pore diameter much larger than that of conventional coal and dry coal.

<No. 3: Amount of oxygen-containing functional group>
By measuring the infrared absorption spectrum of subbituminous coal (US PRB charcoal) while raising the temperature (10 ° C./min) in a nitrogen atmosphere, oxygen-containing functional groups (hydroxyl group (OH), carboxyl group (COOH), aldehyde The content ratio of each group (COH) and ester group (COO) at each temperature was determined. The result is shown in FIG. The horizontal axis represents temperature, and the vertical axis represents the ratio of the peak area of each oxygen-containing functional group to the total peak area of the oxygen-containing functional group at 110 ° C.

  As can be seen from FIG. 3, it was confirmed that the oxygen-containing functional group, that is, the tar-generating group, almost disappeared at 460 ° C. and disappeared at 500 ° C.

<No. 4: Combustibility>
The relationship between the ratio of unburned carbon remaining when the above-described coal of the present invention was burned with air at 1500 ° C. and the supply flow rate of air was determined. Moreover, the case of the conventional charcoal and dry charcoal mentioned above was also calculated | required for the comparison. The result is shown in FIG. In FIG. 4, the horizontal axis represents the residual oxygen concentration in the combustion exhaust gas after burning the charcoal, in other words, the excess oxygen concentration, and the vertical axis represents the unrecovered amount after the charcoal was burned. Represents the proportion of fuel carbon.

  As can be seen from FIG. 4, the amount of unburned carbon in the conventional coal and the dry coal gradually increases as the excess oxygen concentration decreases. On the other hand, it was confirmed that the charcoal of the present invention can be burned substantially completely without increasing the amount of unburned carbon even when the excess oxygen concentration is lowered.

<No. 5: Combustion temperature>
The relationship between the excess oxygen ratio and the combustion temperature when the above-described coal of the present invention was completely burned 100% under the following conditions was determined. For comparison, the above-described conventional charcoal was also obtained. The result is shown in FIG. The excess oxygen ratio Os is a value defined by the following formula (1).

* Combustion type C + O ₂ → CO ₂
H ₂ + 1 / 2O ₂ → H ₂ O

* Combustion conditions and supply air temperature: 1200 ° C
-Air oxygen concentration: 21 vol. %
・ Coal supply temperature: 25 ℃
-Adhering water: 2%

Excess oxygen ratio Os = (Oa + Oc / 2) / (Cc + Hc / 4) (1)
Where Oa is the molar flow rate of oxygen gas (molecules) in the supply air, Oc is the oxygen atomic molar flow rate in the supplied coal, Cc is the carbon atomic molar flow rate in the supplied coal, and Hc is hydrogen in the supplied coal. Atomic molar flow rate.

  As can be seen from FIG. 5, the coal of the present invention has a lower calorific value than that of the conventional coal, but it has been confirmed that the combustion temperature is higher than that of the conventional coal when the excess oxygen rate is the same as that of the conventional coal. This is because the present invention charcoal has a higher oxygen content than the conventional charcoal, and if the excess oxygen ratio is the same as that of the conventional charcoal, the supply air amount can be smaller than that of the conventional charcoal.

  The blast furnace blown coal and the manufacturing method thereof according to the present invention can be used extremely beneficially in the coal industry, the steel industry, and the like.

11 Low-grade coal (subbituminous coal or lignite)
12,22 Blast furnace injection coal S11 Drying step S12 Carbonization step S13, S23 Cooling step S14 Fine grinding step S25 Partial oxidation step

Claims (5)

Blast furnace-blown charcoal that is blown from the tuyere into the blast furnace body of the blast furnace facility,
The oxygen atom content ratio (dry base) is 10 to 20% by weight,
Blast furnace blown charcoal characterized in that the average pore diameter is 10 to 50 nm. In the blast furnace injection coal according to claim 1,
Blast furnace blown charcoal characterized by having a pore volume of 0.05 to 0.5 cm ³ / g. In the blast furnace injection charcoal according to claim 1 or claim 2,
A specific surface area is 1-100 m < ² > / g. Blast furnace injection charcoal characterized by the above-mentioned. It is a manufacturing method of the blast furnace injection charcoal as described in any one of Claims 1-3,
A drying process for heating sub-bituminous coal or lignite to remove moisture;
A carbonization step of carbonizing the charcoal dried in the drying step at 460 to 590 ° C. In the manufacturing method of the blast furnace injection coal of Claim 4,
A cooling step of cooling the charcoal carbonized in the carbonization step to 50 to 150 ° C .;
And a partial oxidation step in which oxygen is chemically adsorbed by exposing the charcoal cooled in the cooling step to an oxygen-containing atmosphere at 50 to 150 ° C to perform partial oxidation. .

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