JPS59135284A - Fuel to be blown into blast furnace - Google Patents

Abstract

PURPOSE:To provide a low cost fuel for blowing into a blast furnace in place of heavy fuel oil, prepared by removing light fractions from byproduct crude tar from a coke oven. CONSTITUTION:A crude tar obtained as byproduct from a coke oven is heated to 250-300 deg.C and light fractions (tar gas oil - washed oil) are distilled out. The resultant residue (anthracene oil - pitch, the so-called road tar) is used as duel to be blown into a blast furnace. The road tar may be used as it is or blended with crude tar for reduction of viscosity or with about 60wt% in total pulverized coal (preferably containing about 70-80% particles with a diameter of about 74mu) and a basic substance (e.g. CaO, CaCO3 and MgCO3).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel for blast furnace injection, and particularly to a fuel for blast furnace injection that can be used in place of heavy oil.

Conventionally, in blast furnace operation, fuel consumption and furnace heat control,
Furthermore, in order to improve the operating rate and achieve stable operation of blast furnaces, it is widely practiced to inject heavy oil along with hot air through the tuyere. However, since the oil crisis, the price of heavy oil has skyrocketed, and there is a problem of resource depletion. The method of injecting heavy oil itself into a blast furnace is becoming economically disadvantageous due to problems such as instability of supply. Against this background, conventional countermeasures include (1) a mixture of heavy oil and pulverized coal, (2) a mixture of coarse tar and pulverized coal,
(3) Research is underway to replace some or all of the heavy oil for blast furnace injection by using pulverized coal.
Some of them have already been implemented in actual blast furnaces.

However, (1) In the case of a mixture of pulverized coal and heavy oil, the pulverized coal concentration in the mixture is generally 60% due to viscosity.
The amount that can be substituted for heavy oil for blast furnace injection is limited,9 and it is impossible to replace the entire amount.

Therefore, the reality is that they will not be able to cope with the increasingly serious rise in heavy oil prices.

(2) In the case of a mixture of coarse tar and pulverized coal, it is significant that the crude tar by-produced within the steelworks and inexpensive pulverized coal can be used to replace the entire amount of heavy oil for blast furnace injection. but,
Crude tar contains various aromatic hydrocarbonized water ices that are useful as raw materials for the chemical industry.1. It is advantageous both in terms of effective resource utilization and economic efficiency to inject this into the blast furnace without separating it. When heated and held above ℃, some of the coarse tar, mainly □ and light components, penetrates into the pulverized coal, decreasing the apparent liquid concentration and increasing the viscosity, causing storage and
Yobikenro Transport Menblade.

This will cause difficulties.

(3) In the case of using only pulverized coal, the disadvantages of (1) and (2) above can be overcome because the pulverized coal is blown into the blast furnace by gas transport without using any liquid fuel. However, there are technical problems that have not been completely solved, such as flow distribution control to the blast furnace tuyeres and flow measurement. Second, it requires safety measures such as coal dust explosion, and second, it has the disadvantage that the equipment cost is higher than the two top filling methods.
- Therefore, the present invention aims to solve the problems of the above three methods, and specifically, it was accomplished with the following points in mind.

・′□′1 ′ ′(1) No heavy oil is used at all, instead of heavy oil for blast furnace injection.
Replaced with accounting.

(2) Use tar generated within the steelworks.

(3) Separate the light components of the tar □, which contain a large amount of useful components, and use the remainder as fuel for blast furnace injection〇(4) Use the fuel in (3) above as necessary. Coarse tar, pulverized coal, and basic substances are used to adjust viscosity, increase fuel temperature, and reduce S and Si content in pig iron.

(5) Eliminate the phenomenon of thickening over time, as seen in coarse tar/pulverized coal mixtures, or reduce the rate of thickening.・'(6) Conventional liquid monomer: It is possible to use the original slicing or slurry fuel injection technology equipment, and no special technology development is required.

That is, according to the first invention, there is provided a blast furnace injection fuel that uses the residue obtained by distilling coarse tar by-produced from a coarse coal furnace at 250 to 300° C. and removing light components.

According to the invention of the first step, the crude tar by-produced from the coke oven is distilled at 250 to 30°C□, and the light components are removed. A fuel for blast furnace injection is provided which is characterized by the above-mentioned features.Basically, in place of heavy oil, the present invention uses crude tar produced by-product from a coke oven, especially coarse tar, in place of heavy oil. The aim is to reuse the residue after separating the light components as fuel for blast furnace injection. In other words, coarse tar contains light components such as
Because it contains useful substances such as tar gas oil, carpol oil, nametarile oil, and cleaning oil, these substances can be separated and used separately as raw materials for the chemical industry.
The residue is used as fuel for blast furnace injection.

Furthermore, in detail, by heating the crude tar by-produced from the coke oven at a temperature of 250 to 300°C, the light components (tar light oil to cleaning oil) are separated, and the residual components (anthracene oil to pitch) (hereinafter referred to as load) are separated. (called tar) in a blast furnace.

Used as injection fuel. The heating temperature of crude tar is 25
The reason why the temperature was set at 0 to 300°C was to recover as much useful light content as possible, while also allowing the residual material to remain (5-k y f), and to give the J residue more fluidity. There is. If the residue contains pitch, it will lack fluidity and cause problems in transportation. On the other hand, by removing the light components in the coarse coal and keeping it, it is possible to avoid the thickening phenomenon that occurs over time, even when used in combination with □ and pulverized coal, as described later. This □ point is also true. □ The components of the □ road tar used in the present invention are generally as shown in Table 1, and are almost the same as crude tar in terms of composition.

This road tar can also be used alone as fuel for blast furnace injection. In this case, the road tar is blown into the blast furnace by almost reusing the existing high filtration liquid injection equipment. However, if it is difficult to inject road tar alone into a blast furnace due to pump performance, etc., by mixing coarse tar, which has a lower viscosity than road tar, the overall viscosity can be lowered and the equipment used can be improved. The viscosity can also be adjusted to suit. FIG. 1 shows the relationship between road tar concentration and viscosity in a road tar/crude tar mixture. In this way, by selecting the mixing ratio and temperature according to the specifications of the injection equipment, it is possible to perform injection into the blast furnace using existing liquid fuel injection equipment. In particular, it can be used in combination with pulverized coal. Coal has abundant reserves of steam coal other than caking coal for coke raw material, and its price is lower and more stable than heavy oil, making it suitable as a fuel for blast furnace injection. Generally, when coal is injected into the blast furnace through the tuyere, it is pulverized and used in the form of pulverized coal, and pulverized coal alone is injected by gas transport or mixed with liquid fuel and used in the form of a slurry. I can't believe it. In the former case, as mentioned above, there are technical problems such as flow rate distribution control and problems such as coal dust explosion, but according to the present invention, pulverized coal is added to the road tar alone or the road tar/coarse tar mixture. Since it is mixed and used in the form of a slurry, the above-mentioned problem can be solved.

Furthermore, since there is a production limit to the amount of tar generated within a steelworks, it is advantageous to be able to increase the overall amount of fuel for blast furnace injection by mixing it with pulverized coal. Furthermore, when using a mixture of coarse tar and pulverized coal, at a temperature of approximately 70°C, a thickening phenomenon in which the viscosity increases over time is observed as shown in Figure 2, and storage and Although a problem occurs during pipe transportation, when road tar and pulverized coal are used in combination, no thickening phenomenon is observed, as is clear from FIG. 2. This is considered to be because the thickening phenomenon occurs when light components in the coarse tar penetrate into the pulverized coal, lowering the apparent liquid concentration and, as a result, increasing the viscosity. On the other hand, when using pulverized coal in the road cool/coarse cool mixture,
Although there is a slight thickening phenomenon, the thickening rate can be kept low compared to the case of a mixture of coarse tar and pulverized coal.

Generally, the upper limit of the amount of pulverized coal to be mixed is determined by the permissible viscosity of the fuel for blast furnace injection. However, while the viscosity of tar-based substances changes with temperature, the viscosity that is allowed as fuel for blast furnace injection also differs depending on the presence or absence of equipment used, such as pumps and heating equipment. Therefore, the critical viscosity is not necessarily determined uniquely, but is determined based on the cost of equipment, maintenance, and benefits obtained from blowing. It is determined by the situation and the location conditions of the blast furnace. However, the conditions for injecting slurry fuel into the blast furnace are usually at a temperature of 70 to 100°C.

The viscosity is 2000 cp or less, and under these conditions, the concentration of pulverized coal mixed with the road tar alone or the road tar/crude tar mixture is generally 60 wt% or less. As is clear from FIG. 3, when the concentration of pulverized coal in the slurry exceeds 60 wt%, the viscosity increases rapidly.

The particle size of the pulverized coal used in the present invention is not particularly limited, but it is generally 1200 mes from the viewpoint of combustibility in the blast furnace.
h(74μ) content of about 70 to 80 is often used.

The blast furnace injection fuel of the present invention further includes, if necessary,
Basic substances can be added, such as those that function as desulphurizing agents and desiliconizing agents. The basic substances added include CaO+CaCO3, Ca, (OH)2. M
Examples include gO, MgCO3, Mg(OH)2, and the like. There is no particular limitation on the particle size of the basic substance to be added, as long as it does not precipitate during flow. The amount added is preferably 5°wt% or less.

Along with pulverized coal, road tar alone or road tar/
When mixed into a crude tar mixture, the total concentration of the basic substance and pulverized coal is preferably 5 (Jwt% or less). If the amount exceeds these amounts, the viscosity becomes large;
Transportation becomes difficult.

Generally, in blast furnaces, the CaO/5iO2 (basicity) in the charge is adjusted to promote desulfurization in the furnace, but if the basicity is too high (9), the viscosity of the slag becomes high and This will cause deterioration of the properties and hanging of the shelf, which will have a significant negative impact on the condition of the furnace.

Therefore, if a basic substance is injected together with fuel through the tuyeres as in the present invention, there is no need to use a charge with high basicity9, and the above-mentioned disadvantages are eliminated. In addition, since the lower part of the furnace is in a very high temperature state, even if the slag has a high basicity, its fluidity is maintained extremely well, and desulfurization in the furnace is accelerated without adversely affecting the furnace condition. Furthermore, as the basicity of the slag increases, the amount of dissolved SiO2 in the slag decreases, and as a result, 81 in the pig iron also decreases, and a desiliconization effect can be expected.

Next, the effects of the present invention will be explained based on examples.

Example Conventional blast furnace injection fuels A to C prepared at the mixing ratios shown in Table 2 and blast furnace injection fuels D to and B according to the present invention were mixed together with hot air in a blast furnace under the operating conditions shown in Table 3. I'm blowing into it.

Table 2: CaO is used as the basic substance Table 3: If a basic substance is added, the net amount of fuel after removing the basic substance.The composition of each material constituting the various fuels is shown in Table 1. This is a guide to show. Further, the particle sizes of pulverized coal and basic substances are shown in Table 4.

The results of each fuel injection are summarized as coke ratio, S value in pig, S in pig
It is also shown in Table 2 as the i value.

As is clear from the results shown in Table 2, the coke ratio during blast furnace injection and fuel injection of the present invention is comparable to the coke ratio during conventional fuel injection; It can be seen that it can be used sufficiently as a commercial fuel. Also,
Regarding the effect of basic substances, as is clear from Table 2, the S and St fractions contained in pig iron are low compared to fuels containing basic substances. You can see the effect.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the relationship between road tar concentration and viscosity for a mixture of road tar and coarse tar, and Figure 2 is an explanatory diagram showing the relationship between time change and thickening effect for a mixture of rotary tar, coarse tar, and pulverized coal. , Figure 3 is a rotary reel,
FIG. 2 is an explanatory diagram showing the relationship between viscosity and pulverized coal concentration for a mixture of coarse tar and pulverized coal. Patent applicant: Sumitomo Metal Industries, Ltd. / Patent attorney: Yoshihisa Nagai Figure 1: Figure 2: Figure 3: Roll letter IL (60-Ling) 40J chapter)
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Claims (2)

[Claims] (1) Crude tar produced as a by-product from a coke oven
A fuel for blast furnace injection characterized by using a residue obtained by distilling at 300°C and removing light components. (2) Crude tar produced as a by-product from a coke oven
A fuel for blast furnace injection, characterized in that one or more of crude tar, pulverized coal, and basic substances are added to the residue obtained by distilling at 300° C. and removing light components.