JPS581163B2 - Blast furnace operating method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of operating a blast furnace.

In normal blast furnace operation, in order to achieve a low fuel ratio and furnace heat control, as well as to improve the operating rate and stable operation of the blast furnace, a method of injecting liquid fuel such as heavy oil together with hot air through the tuyeres is widely adopted.

That is, in order to maintain stable blast furnace operation and reduce the coke consumption rate, the current situation is that liquid fuel (heavy oil) is conventionally operated at a rate of about 200 l/tuyere/hour or more from the blast furnace tuyere.

However, in recent years, especially after the oil crisis, the price of heavy oil has skyrocketed, and there is also the problem of resource depletion, and it has become impossible to inject enough heavy oil into the furnace from all tuyeres. For example, odd number numbers.
It became necessary to inject heavy oil from the tuyere of 1 or even number of tuyere, and the amount of heavy oil injection was increased to 20 tuyere.
There is no choice but to keep it below 0t/tuyere/Hr.

However, the former heavy oil injection method that uses adjacent tuyere alternately lacks smooth injection balance in the circumferential direction of the blast furnace.
This leads to deterioration of the furnace condition and an increase in the fuel ratio, making it impossible to contribute to stable operation of the blast furnace.In addition, in the latter method of reducing the amount of heavy oil injection, the heavy oil flow rate in the injection burner decreases and solidifies, resulting in burner clogging. A problem has arisen in that fluctuations in the amount of injection become large, which adversely affects the furnace condition.

Humidity-controlled blowing is also generally carried out as part of the stable operation of blast furnaces.This involves blowing hot air containing water vapor into the furnace through the tuyeres, suppressing the increase in the volume of botshu gas in front of the tuyere, and blowing through the blast furnace. The aim is to prevent abnormal phenomena such as suspension and slippage, improve productivity, lower coke ratio, and increase air temperature.

However, as mentioned above, the reduction in the amount of heavy oil injected causes an increase in the combustion temperature before the tuyere, leading to an increase in the volume of botshu gas.In order to maintain stable furnace conditions, it is necessary to lower the air blowing temperature or reduce the air humidity. An increase must be made.

As a result of conducting various research experiments to address the above-mentioned problems, the present inventor has achieved stable operation of a blast furnace by reducing or not using liquid fuel such as heavy oil without alternately using adjacent tuyeres. I was able to find something to help.

That is, the present invention blows water or a mixed fuel of water and liquid fuel (heavy oil) into the furnace from the tuyeres together with hot air as an alternative to liquid fuel such as heavy oil, and adjusts the amount of water based on the unloading status of the charge at the top of the furnace. Alternatively, it is characterized by operating the blast furnace while measuring the increase or decrease in the amount of mixed fuel, and will be described in detail below based on the attached drawings and its effects will be demonstrated.

First, Figures 1 and 2 show an embodiment of a means for replacing liquid fuel such as heavy oil with water and injecting it into the furnace from a tuyere. In each figure, 1 is the blast furnace main body, and 2 is the furnace. A large number of tuyere 3 are arranged around the body, and reference numeral 3 is a blow pipe of a branch pipe connected to the tuyere 2 .

A water blowing nozzle 5 is installed in the hot air passage 4 at the front of the blow pipe 3 so that its tip 6 can be seen as shown in FIG.

Further, the water injection nozzle 5 is connected to water supply branch pipes 9 which are branched from a water supply main pipe 8 led by a water supply pump 7, and when the water supply pump 7 is operated, the water storage tank 10 is
The water inside passes through the main water supply pipe 8 and the water supply branch pipe 9 to the water injection nozzle 5.
The hot air is blown into the blast furnace through each tuyere 2 together with the hot air from the blowpipe 3 of the blower branch pipe.

Further, the main water supply pipe 8 and each water supply branch pipe 9 are provided with cutoff valves 11, 12 and regulating valves 13, 14, respectively, and the regulating valve 13 for the main pipe 8 is provided with a temperature regulator 15, an atmospheric hygrometer 16, and an atmospheric hygrometer 16. Although not shown, the amount of water supplied can be controlled by a water amount regulator 17 that operates based on various commands from Southingrod, for example, to control the ever-changing distribution of unloading of the burden at the top of the blast furnace. There is.

In this way, the blast furnace is operated while blowing water together with hot air into the blast furnace, and the water blown into the furnace reacts as described below.

That is, water is vaporized by hot air (approximately 1200° C.) according to the following formula (1), and after the vaporization, a reaction according to formula (2) occurs in front of the tuyere in the furnace.

H2O (water) → H2O (steam) -9.7 kcal/g
-mol ・・・・・・(1)H2
O (steam) + C (coke) → H2 + CO-31.2
kcal/g-mol (2) Therefore, the increase in the volume of botshu gas in front of the tuyere is suppressed by the endothermic reaction due to the water gas reaction as well as the sensible heat and heat of vaporization during water vaporization, and the furnace condition stabilizer The effect is significant.

In addition, a portion of the hydrogen generated from the above equation (2) reduces iron ore in the furnace according to the following reaction equation.

Fe2O3+3H2→2Fe+3H2O−21.8
kcal/g-mol...
(3) Fe3O4 +4H2→3Fe +4H2O −
35.3kcal/g-mol・
...(4) FeO +H2→Fe+H2O -6
．． 7kcal/g-mol...
...(5) The water injected from this will suppress the immediate increase in the volume of bosch gas and will be generated into reducing gas, which will greatly contribute to stable operation of the blast furnace, improvement of productivity, and reduction of coke ratio. I understand that.

In addition, as the amount of water blown increases, the CO concentration and H2 concentration in the Botschu gas increase, which greatly contributes to improving productivity and lowering the coke ratio, but on the other hand, it causes a lack of furnace heat and causes cooling. , Therefore, based on each command from the humidity regulator 15, atmospheric hygrometer 16, and Southing rod (not shown), the water flow regulator 17 is
As a result,
The amount of water injected is 100L/Hr to 250L/Hr per panel.
By adjusting within the Hr range, stable blast furnace operation can be achieved.

Next, FIG. 3 will be explained.

In this case, one embodiment of the means is shown in which a mixed fuel made by suspending and mixing liquid fuel such as heavy oil and water is injected into the furnace through the tuyere.

In the drawings, the same reference numerals indicate the same or equivalent parts.

That is, a mixed fuel injection nozzle 18 is provided in the blow pipe 3 of the blowing branch pipe connected to the tuyere 2 of the blast furnace main body 1, and the mixed fuel injection nozzle 18 is connected to a fuel supply main pipe equipped with a cutoff valve 11 and a regulating valve 13. 19 is connected to a fuel supply branch pipe 20 having a cutoff valve 12 and a regulating valve 14, which are branched from each other.

Further, on the upstream side of the cutoff valve 11 and the regulating valve 13 of the fuel supply main pipe 19, its end is connected to a mixed fuel tank 23 via a heater 21 and a pump 22, and the mixed fuel tank 23 is connected to a water storage tank 24. The water supply pipe 25 from the pump 2
6.

Further, in the figure, 27 is a tank heater for heating the mixed fuel, and 28 is a stirrer for suspending and mixing liquid fuel such as heavy oil in the mixed fuel tank 23 with water.

In this way, a mixed fuel of liquid fuel such as heavy oil and water is blown into the furnace of the blast furnace main body 1 through the tuyere 2 along with hot air from the blow pipe 3 of the blast branch pipe. The water in the tank 24 is supplied into the mixed fuel tank 23 by operating the pump 26 to make the ratio of heavy oil and water, for example, 1:1.
7 with a stirrer 28 while heating to at least 80°C or higher.
After that, the pump 22 is passed through the heater 21, and while being heated, the fuel supply main pipe 19 and the fuel supply branch pipe 20 are mixed.
After that, the mixed fuel is blown into the blast furnace main body 1 from each tuyere 2 through the respective mixed fuel injection nozzles 18 together with the hot air from the blow pipe 3.

Here, the water in the mixed fuel is as described in (1), (
At the same time as the reactions shown in equations 2), (3), (4), and (5), the heavy oil component causes the reaction shown in equation (6) below.

Cv・Hm→m/2H2+vc-440 Kcal/k
g...(6) Therefore, stable operation of the blast furnace can be achieved with a higher coke ratio reduction.

Although the amount of the mixed fuel injected is not shown in the figure as described above, for example, the adjustment valve 13 of the main pipe 19 and each branch pipe are 20 regulating valves 14
The injection amount of the mixed fuel corresponding to the above-mentioned charge unloading distribution, that is, 100 l/Hr per tuyere, is controlled respectively.
The blowing is adjusted from each tuyere 2 around the furnace body within the range of ~2501/Hr.

In addition, the amount of water or mixed fuel injected as a substitute for liquid fuel is adjusted so that the amount injected from the side corresponding to the area where the amount of charge unloading in the circumferential direction at the top of the furnace is large. death,
Conversely, in areas where the amount of unloading is small, the amount of blowing from the tuyere corresponding to that area may be adjusted to be smaller.

The present invention is a blast furnace operating method carried out as described above, and will be explained next based on the results of the implementation.

A blast furnace with an internal volume of 2700 m3 and 28 tuyeres was operated, and the results shown in the table below were obtained.

From this, it was confirmed that the method of the present invention reduced the number of slips compared to the conventional method, and achieved stable operation of the blast furnace.

In this case, method B of the present invention is comparable in corrected fuel ratio to conventional method D, while method A is slightly higher.

Also, although the number of slips has increased, this does not pose a problem to blast furnace operation.

As described above, according to the method of the present invention, in order to reduce the amount of heavy oil blown into the furnace from the conventional tuyeres and to ensure stable operation of the blast furnace, adjacent tuyeres can be used alternately and water vapor can be contained in the blown hot air. Water or a mixed fuel of water and heavy oil is injected into the furnace as an alternative to liquid fuel such as heavy oil, which is blown in with hot air from the tuyere, without causing any damage. Therefore, it is easy to achieve the initial objective of stable operation of the blast furnace. This is an operating method that has the beneficial effects of being able to achieve this, as well as reducing the coke ratio and fuel ratio.

[Brief explanation of drawings]

The attached drawings show embodiments of the method of the present invention, and Fig. 1 is an explanatory diagram showing the blast furnace operating method in the case of water injection, Fig. 2 is an enlarged cross-sectional view of the main part, and Fig. 3 is an illustration of water and heavy oil. FIG. 2 is an explanatory diagram showing a blast furnace operating method in the case of mixed fuel. 1 is the blast furnace, 2 is the tuyere, 3 is the blow pipe of the ventilation branch pipe, 5
is a water blowing nozzle, 8 is a water supply main pipe, 9 is a water supply branch pipe, 11,
12 is a shutoff valve, 13 and 14 are regulating valves, 18 is a mixed fuel injection nozzle, 19 is a fuel supply main pipe, and 20 is a fuel supply branch pipe.

Claims (1)

[Claims] 1 In a blast furnace, water or a mixed fuel of water and heavy oil is blown into the furnace along with hot air from each tuyere corresponding to the unloading distribution at the top of the furnace, which changes from moment to moment, while adjusting the required amount. A blast furnace operating method characterized by