JPH0368710A - Water cooling method for blast furnace contents - Google Patents

Abstract

PURPOSE:To prevent gas explosion caused by hydrogen by blowing nitrogen, etc., from tuyere to dilute generated hydrogen gas at the time of cooing contents in the furnace by pouring water just after stopping blasting from the tuyere after completing lowered stock level and blowing-down in blast furnace operation. CONSTITUTION:At the time of lowering the stock level and blowing-down in a blast furnace 1, at first after charging as increasing coke, the charging of raw material is stopped and while continuing the blasting from the tuyere 3, the raw material level is lowered and water is sprayed in the furnace with water spraying pipes 3 to make the furnace top gas temp. the prescribed temp. or lower. According to lowering of the raw material level, the blasting rate is decreased step by step, and when the raw material level reaches the tuyere 3 level, the blasting from the tuyere 3 is stopped and blowing pipe in the prescribed tuyere is take off and the blowing pipe for nitrogen gas, etc., is inserted to blow the nitrogen gas or steam into the furnace. By this method, the hydrogen gas generated in the furnace is diluted to less than explosion limit to execute safe lowered stock level and blowing-down.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to the H2
The present invention relates to a method for cooling the contents of a blast furnace by injecting water into the furnace to prevent gas explosions (or abnormal combustion) caused by gas explosions (or abnormal combustion).

[Conventional technology] The reduced-scale blowdown method for blast furnaces involves stopping the charging of raw materials from the top of the furnace, and burning the coke with high-temperature air sent through the tuyere to lower the raw material level to the tuyere level (reducing the level). As the B gas generated during scale reduction operations becomes hotter as the scale reduction progresses, water is sprinkled from the top of the furnace to protect the equipment.As the scale reduction progresses, the air flow rate is gradually reduced. When the raw material level reaches the tuyere level, the air blowing from the tuyere is stopped. Thereafter, the raw material in the furnace was cooled by continuing water sprinkling, and the raw material was discharged from a plurality of raw material scraping holes provided in the sump to perform air blowdown.

[Problems to be Solved by the Invention] Immediately after the completion of reduced-scale blow-off, red-hot coke remains in the furnace, and water is sprinkled to cool the contents in the furnace. At that time, red hot coke and water react (formula below)
H2 gas is generated, with high concentrations sometimes exceeding 4%.
There is a risk of explosion if mixed with furnace air (H2
The lower explosive limit is 4%).

H20+C-"H2+C○ There was a problem in that this explosion damaged the furnace top equipment, etc.

[Means for Solving the Problems] This invention attempts to solve the above-mentioned problems, and while the charging of raw materials into the blast furnace is stopped, air is continued to be blown from the tuyere, and the inside of the furnace is After the charge level has been reduced to the tuyere level by discharging it while melting it one by one, and the raw material level has been lowered to the tuyere level, immediately after the air blowing is stopped, when cooling the contents in the furnace, the tuyere Blow nitrogen or steam through the mouth,
This is a method of cooling the contents of a blast furnace by injecting water into the furnace, which is characterized by diluting the hydrogen gas generated.

``Effect'' After stopping air blowing, nitrogen gas or steam is blown in from the tuyere to dilute the generated hydrogen gas and carbon monoxide and maintain them below the explosion limit, thereby preventing gas explosions in the furnace.

[Example] Examples of the present invention will be described in detail below. FIG. 1 is a vertical cross-sectional view showing the installation of a blowing pipe for nitrogen gas, etc., and FIG. 2 is a vertical cross-sectional view showing the state of the blast furnace during reduced-scale blowdown. 1 is a blast furnace, 2 is a plurality of water pipes installed at the top of the blast furnace, 3 is a tuyere, 3
1 is a small tuyere, 32 is a large tuyere, 4 is a metal fitting for the tuyere holder, and 5 is a nitrogen gas or steam blowing pipe. 6 is the remaining raw material upon completion of scale reduction and blowdown. Reducing the scale and blowing down are carried out as follows. First, increase the charge of coke, then stop charging the raw material. Continue blowing air from the 0 tuyere to lower the raw material level. Decrease the raw material level. As a result, the gas temperature at the top of the furnace rises (more than 500℃), so in order to protect the charging equipment, etc. at the top of the furnace, water is sprinkled into the furnace from the water sprinkler pipe 2 to keep the gas temperature at the top of the furnace below a predetermined temperature. Cool to

In addition, the method of the present invention gradually reduces the amount of air blown as the raw material level falls, and when the raw material level reaches the tuyere level, the air blowing from the tuyere is stopped and the blowdown is completed. In such a work process, after the raw material level reaches the tuyere and the blowing is stopped, the blow pipe of the specified tuyere is removed and a separately prepared nitrogen gas blowing pipe 5 (for example, 100φ) is used. The tip of the steel pipe is made to protrude into the furnace from a small tuyere, and nitrogen gas or steam is blown into the furnace. The amount of nitrogen gas etc. injected must be such that the concentration of hydrogen gas generated by the red hot coke in the residual raw material is diluted to below the explosive limit (the lower explosive limit is 4%). For blast furnace, 4000
~5000r+(/Hr).

Note that if nitrogen gas and steam cannot be used alone due to the supply and demand balance of nitrogen gas and steam, nitrogen gas and steam may be injected in combination.

[Effects of the Invention] This invention dilutes the hydrogen gas generated by blowing nitrogen gas or steam through the sidings after the air blowing has stopped, thereby bringing the inside of the furnace below the explosion limit. Capable of blowing and unloading at a reduced length.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing the installation of a blowing pipe for nitrogen gas, etc. used in the method of the present invention, and FIG. 2 is a vertical cross-sectional view showing the state of the blast furnace during reduced-scale blowdown. 1... Blast furnace, 2... Water pipe, 3... Tuyere, 31.
...Small tuyere, 32...Large tuyere, 4...Tuyere support is hardware, 5...Blowing pipe, 6...Residual raw material.

Claims (1)

[Claims] Immediately after stopping the charging of raw materials into the blast furnace and continuing blowing air from the tuyere, the charge in the furnace is sequentially melted and discharged, and after the raw material level has completely dropped to the tuyere, the blowing of air is stopped. 1. A method for cooling the contents of a blast furnace by injecting water into the furnace, which is characterized by blowing nitrogen or steam through a tuyere to dilute the generated hydrogen gas when cooling the contents of the blast furnace.