JPH03191013A - Method for cooling blast furnace - Google Patents

Abstract

PURPOSE:To efficiently cool charged materials and a furnace bottom part in a blast furnace by pouring cooling water into the furnace from an iron tapping hole and also draining this from a drainage hole at the height of tuyere level or more after stopping blowing into the blast furnace. CONSTITUTION:After stopping the blowing, water supplying pipe 4 providing a valve 3 is connected with the iron tapping hole 2 in the blast furnace 1. On the other hand, the drainage hole 7 is opened at the height position on the furnace wall 6, where all charged materials 5 are dipped into water at the height tuyere level 11 or more, and the drainage pipe 9 providing the valve 8 is connected with the drainage hole. Successively, the valves 3, 8 are opened, and the water is poured in the furnace from the iron tapping hole 2 and also drained from the drainage hole 7. Then, it is desirable that explosion of hydrogen gas is prevented by controlling the pouring velocity of cooling water so as not to exceed 10% hydrogen gas concn. at the furnace top part. By this method, the charged material 5 in the furnace and remaining iron 10 at the furnace bottom are cooled in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for cooling a blast furnace charge and a furnace bottom after blow-stopping.

[Prior Art] A blast furnace for producing hot metal from iron ore will operate continuously for 5 to 10 years once fired. During this time, damage progresses to each part of the blast furnace body, and eventually it becomes difficult to maintain a predetermined production capacity. Therefore, in such a situation, it becomes necessary to carry out repairs mainly by replacing the refractory bricks that make up the furnace.

In order to repair a blast furnace efficiently in a short period of time, it is necessary to stop the air supplied for combustion, and at the same time remove as much of the high-temperature charges, molten slag, hot metal, and bottom of the furnace as possible that remain in the blast furnace. It is necessary to cool it quickly.

In the conventional method of cooling the charge and the bottom of the blast furnace, cooling water is injected from the top of the furnace immediately after the combustion air is stopped, and the amount of water injected is gradually reduced to the extent that the temperature of the top gas does not rise too much. The method was to increase the number of

[Problems to be Solved by the Invention] However, the conventional blast furnace cooling method has the following problems.

(1) Water is injected from the top of the furnace using several nozzles,
When looking at the horizontal cross section of the furnace, there are areas where the cooling water is sufficiently applied and areas where it is not, resulting in insufficient cooling as a whole.

(2) In the early stage of water injection, the poured cooling water evaporates in the upper part of the furnace and forms an upward gas flow, which delays the cooling of the middle and lower parts of the furnace. In addition, only hot water is supplied to the bottom of the furnace, which requires the most cooling, resulting in poor cooling efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a blast furnace cooling method that solves the above-mentioned problems of the prior art and allows efficient cooling of the blast furnace charge and the bottom of the blast furnace after blowdown.

[Means for Solving the Problems] In the blast furnace cooling method according to the present invention, when cooling the blast furnace charge and the bottom of the furnace after blow-stopping, cooling water is injected into the furnace from the taphole and the tuyere This is a blast furnace cooling method in which water is drained from a height higher than that of the blast furnace, and in this cooling method, the cooling water injection rate is controlled so that the hydrogen gas concentration at the top of the furnace does not exceed 10%.

[Function] In the blast furnace cooling method according to the present invention, when cooling the blast furnace charge and the bottom of the furnace after blowdown, cooling water is injected into the furnace from the taphole, and water is drained from a height above the siding level. I try to do that.

The reason is as follows. In this cooling method,
Since the cooling water is supplied directly to the high temperature area near the hearth, the rate of water gas reaction between water and red-hot coke is significantly increased, in addition to the vaporization of water. Generally, endothermic reactions caused by cooling water are roughly classified into the following two types.

(1) Endothermic H2O (liquid) due to vaporization + 720.000 Kcal/T
onH20→H20 (gas)...(1) (2) Endothermic C+820+1,600,000 Kcal/Ton due to water gas reaction
H20→CO+H2 (2) First, the injected cooling water absorbs 720,000 Kcal of heat per ton and becomes water vapor, as shown in equation (1). Then, this water vapor and coke react as shown in equation (2) to generate CO and H2, but at this time, the amount of cal is reduced to 1.600000 per ton of water.
Therefore, in total, 2,320.000 Kcal of heat is removed per ton of water, compared to the conventional cooling method that only uses the endothermic reaction of equation (1). As a result, the cooling effect is three times or more greater, the amount of cooling water required is small, and the time required for cooling can be shortened.

Further, in this cooling method, the cooling water injection rate is controlled so that the hydrogen gas concentration at the top of the furnace does not exceed 10% for the following reason. In other words, in order to prevent a gas explosion inside the furnace, when injecting water, the inside of the furnace is purged with water vapor or nitrogen gas, and water is injected while maintaining a positive pressure state. H2 gas is generated. If the concentration becomes excessive, there is a possibility of explosion and ignition occurring at the furnace top gas outlet, etc. The inventors believe that explosion and ignition can be prevented if the H2 gas concentration in the furnace top gas is 10% or less. We have empirically confirmed that this is the case, and therefore we decided to inject water under these conditions.

The reason why water is injected from the taphole is that the taphole is already installed and there is no need to make any special opening work for water injection, and the remaining pig iron can be removed immediately after blow-off. If a temporary tap hole is provided at the bottom of the furnace for this purpose, this may be used as a water inlet.

[Example] A cooling method for a blast furnace according to an embodiment of the present invention is shown in Figs. 1 and 2.
This will be explained using figures.

FIG. 1 is an explanatory diagram showing a method for cooling a blast furnace according to one embodiment. After blowing off, a water supply pipe 4 equipped with a water supply valve 3 is connected to the tap hole 2 of the blast furnace 1. Then, a drain lower is opened at a position on the furnace wall 6 at a height where all the furnace charges 5 can be submerged in water, and a drain pipe 9 equipped with a drain valve 8 is connected. After doing this, the water supply valve 3 is opened and cooling water is injected into the furnace.

Figure 2 is a graph showing the transition of the cumulative amount of cooling water injected from the start of cooling to the completion of cooling.
Cooling was performed while controlling the amount of water injected so that the amount of water was below %. As seen in this graph, the conventional method takes 1 minute to complete cooling.
Compared to the previous method, which required 9 hours and a cumulative water injection amount of 1,400 tons, the method of the present invention can shorten the time to complete cooling to 13 hours, approximately 70% of the conventional method, and also reduce the amount of water required for cooling. The amount was reduced to 950 tons, 70% of the conventional amount.

In particular, in this cooling method, the residual pig iron (commonly known as salamander) 10 remaining below the second level of the taphole shown in Fig. 1 is efficiently cooled with low-temperature cooling water, so the residual iron remaining from blasting is The dismantling of the pig iron was also carried out extremely smoothly.

Note that the reference numeral 11 in FIG. 1 is a tuyere.

[Effects of the Invention] According to the present invention, in cooling a blast furnace and blast furnace charge,
The cooling time can be shortened and the amount of cooling water can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a method of cooling a blast furnace according to an embodiment of the present invention, and FIG. 2 is a graph diagram showing changes in cumulative cooling water from the start of cooling to the completion of cooling. 1.Blast furnace, 2.Tapping port, 4.Water supply pipe, 5.Furnace charge, 7.Drainage port, 9.Drainage pipe.

Claims (2)

[Claims] (1) When cooling the blast furnace charge and the bottom of the furnace after blow-stopping, cooling water is injected into the furnace from the taphole, and
A blast furnace cooling method characterized by draining water from a height above the tuyere level. (2) The blast furnace cooling method according to claim 1, characterized in that the cooling water injection rate is controlled so that the hydrogen gas concentration at the top of the furnace does not exceed 10%.