JPH10204510A - Method for igniting furnace top of blast furnace and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means which can safely and quickly ignite combustible gas in the furnace top part of a blast furnace. SOLUTION: An annular injection tube 11 is arranged in one step or plural steps in the furnace height direction in the furnace top part 1 of the blast furnace, and after confirming what the analyzed values of furnace top gas composition are out of explosive range, the air combustion is blown from the annular injection tube 11 according to the raw material layer level and naturally ignited. Further, when the analyzed values of the furnace top gas composition is in the explosive range, inert gas is blown from the annular injection tube according to the raw material layer level and diluted, and after confirming what the analyzed values of the furnace top gas composition comes to out of the explosive range, the air for combustion is blown from the same annular injection tube and naturally ignited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition technique for burning combustible gas at the top of a blast furnace.

[0002]

2. Description of the Related Art Generally, in a blast furnace, when the blast furnace main body or incidental equipment is broken down or repaired, blowing air to the blast furnace is stopped. At this time, combustible gas is generated from the raw material in the furnace and stays in the space at the top of the furnace. Since there is a danger of explosion, it is necessary to burn the combustible gas after sufficiently diluting the gas concentration in the furnace for safety measures in work. The combustible gas generated from the furnace raw material is composed of carbon monoxide (CO) and hydrogen (H ₂ ).

As a method of igniting the combustible gas (CO, H ₂ ) at the furnace top, there is a method in which a fire such as a torch or a flare is injected into the furnace through an opening such as a furnace manhole. However, in this method, there is a danger of the worker falling down due to the suction of the combustion air from the opening, and the danger of the worker being burned out by blowing out the flame from the manhole due to the automatic ignition of the combustible gas in the furnace by the suction of the air. Had a safety problem. Further, at the time of ignition, it is necessary to ignite in the vicinity of the surface of the raw material layer in the furnace, but if the distance between the opening and the surface of the raw material layer is too large (for example, the level of the raw material layer is lowered due to the need for repair). Case), there is a problem that the combustion air (oxygen) required for ignition is difficult to reach, and the ignition operation takes a long time.

[0004] In order to solve such a problem, a method has been adopted in which an ignition burner is provided at the furnace top to ignite combustible gas. For example, Japanese Patent Application Laid-Open No. 6-2411
No. 53, fuel gas is introduced from the inner tube of the inner and outer double tubes, combustion air is introduced from the outer tube, and a dedicated furnace top ignition burner device having an ignition device at the outlet thereof is used. There is a way.

[0005]

However, in the ignition method using a dedicated furnace top ignition burner device, the ignition device is cooled by the fuel gas or combustion air introduced from the inner tube and the outer tube, and the ignition is reliably performed. If the burner ignites for any reason, the furnace head space will be filled with unburned gas and there is a risk of gas explosion. Further, the size of the work deck at the furnace top and the arrangement of various incidental facilities at the furnace top are limited, and it may be difficult to install a dedicated furnace for ignition at the furnace top. In addition, there are restrictions on the level of the raw material layer that can be used depending on the length of the burner. Therefore, the ignition method using the dedicated burner cannot always be said to be effective.

The present invention has been made to solve the problem of the ignition method using the dedicated burner, and employs a spontaneous ignition method by blowing combustion air or an inert gas instead of the ignition method using a burner. This enables safe and rapid ignition of combustible gas at the furnace top, easy installation at the furnace top with limited space for equipment and space, and sufficient for the raw material layer level in furnaces with different heights It is an object of the present invention to propose a method and an apparatus for igniting the top of a blast furnace capable of coping with the above problems.

[0007]

A furnace top ignition method according to the present invention is a method for igniting a combustible gas at a furnace top when a blast furnace is shut down, wherein a ring-shaped injection pipe is provided at the top of the blast furnace at one stage or at a furnace height. When a plurality of stages are installed in the direction, the combustion air or inert gas is injected into the blast furnace from the ring-shaped injection pipe and spontaneously ignites, and the explosion range is outside or outside the explosion range based on the analysis value of the furnace top gas composition. In the case of being within the explosion range, the inert gas is blown from the ring-shaped injection pipe closest to the raw material level position until it is out of the explosion range. Stop the inert gas injection and start the combustion air injection.If the gas composition in the blast furnace is out of the explosion range, blow the combustion air from the ring-shaped injection pipe closest to the raw material level position. It is characterized by the following.

An apparatus for carrying out the method of the present invention includes a furnace port night-vision camera for grasping the state of the raw material layer in the blast furnace, a raw material layer level meter for detecting the position of the raw material layer in the blast furnace, and a furnace top. In a blast furnace equipped with a gas analyzer, a furnace gas pressure gauge and a furnace gas thermometer, and an arithmetic and control unit for adjusting the gas composition in the blast furnace, a ring-shaped injection tube is provided at the top of the blast furnace at one stage or in the furnace height direction. A plurality of stages were installed, and piping was configured so as to supply combustion air or inert gas to each ring-shaped injection pipe from a gas supply system with a flow rate control valve installed outside the furnace, and the furnace top gas determined by the arithmetic and control unit The flow rate control valve is controlled based on the composition.

In the present invention, the ring-shaped injection pipe comprises an annular pipe having a plurality of downward injection nozzles in the circumferential direction of the blast furnace, and combustion air or inert gas introduced from an introduction pipe connected to one end of the pipe. Is configured to be injected into the furnace from the injection nozzle, and a plurality of ring-shaped injection pipes are provided at predetermined intervals (for example, at an interval of 1 to 2 m) in the furnace height direction so as to correspond to a single stage or a blast furnace raw material layer level. A stage (for example, 5 stages) is installed on the furnace wall. The piping is configured such that combustion air and inert gas are supplied to the introduction pipe of each ring-shaped injection pipe from a gas supply system with a flow control valve installed outside the furnace.

A furnace opening night-vision camera for grasping the state of the raw material layer in the blast furnace, a raw material layer level meter for detecting the position of the raw material layer in the blast furnace,
The top gas analyzer, the top gas pressure gauge, the in-furnace gas thermometer, and the arithmetic and control unit for adjusting the blast furnace gas composition are already existing. According to the present invention, the gas composition in the furnace is analyzed by the furnace top gas analyzer, and whether the gas composition is within the explosion range or outside the explosion range is determined by the arithmetic and control unit. When a plurality of ring-shaped injection pipes are installed in the furnace height direction, if the in-furnace gas composition at the furnace top determined by the arithmetic and control unit is within the explosion range, the raw material measured by the raw material layer level meter is used. The arithmetic and control unit determines the ring-shaped injection pipe closest to the bed level, controls the flow control valve of the ring-shaped injection pipe, and checks the gas analysis value from the injection pipe until the inert gas is out of the explosion range. When the gas composition falls within the explosion range, the supply of the inert gas is stopped, and the blowing of combustion air is started from the same ring-shaped injection pipe. The blowing of the combustion air spontaneously ignites the furnace top gas to perform combustion.

Further, as a result of analyzing the gas composition in the furnace with the furnace top gas analyzer, if the gas composition is out of the explosion range, the gas level is most likely to be lower than the raw material layer level measured by the raw material layer level meter as described above. A nearby ring-shaped injection pipe is obtained by the arithmetic and control unit, and a flow regulating valve of the ring-shaped injection pipe is controlled to blow combustion air from the injection pipe to ignite the furnace top gas.

In the present invention, by providing a ring-shaped injection pipe of air or an inert gas at the furnace top as described above, the combustible gas generated from the raw material in the furnace can be spontaneously ignited. The need for an ignition device and its fuel gas is eliminated. In addition, by installing a plurality of ring-shaped injection tubes in the furnace height direction, according to the raw material layer level at that time,
Combustion air and an inert gas for dilution necessary for ignition can be injected into the closest part to the raw material layer level.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing the overall structure of an embodiment of the present invention, FIG. 2 is a plan view showing a ring-shaped injection tube in the above-described apparatus, and FIG. FIG. 4 is a side view, and FIG.
Is the furnace top of the blast furnace, 2 is the charging hole, 3 is the furnace gas outlet, 4
Is a manhole, 5 is a furnace mouth night vision camera, 6 is a raw material layer level meter for detecting a raw material layer position in the blast furnace, 7 is a furnace gas analyzer, 8 is a furnace gas pressure gauge, and 9 is a furnace gas temperature meter. Reference numeral 10 denotes an arithmetic and control unit for adjusting the gas composition in the blast furnace, 11 denotes a ring-shaped injection pipe, 12 denotes an introduction pipe, 13 denotes a gas supply piping system, 14 denotes a flow control valve, and 15 denotes a raw material layer level.

The ring-shaped injection pipe 11 is an annular pipe having a plurality of (for example, eight) downward injection nozzles 11a in the circumferential direction of the blast furnace (made of carbon steel for high temperature and high pressure, and has a pipe diameter of 100A).
), And an introduction pipe 1 connected to one end of the pipe.
The combustion air and the inert gas introduced from 2 are injected into the furnace from the injection nozzle 11a. The ring-shaped injection pipe 11 is provided at a predetermined interval (for example, 1 mm) in the furnace height direction so as to correspond to the blast furnace raw material layer level 15 having different heights.
It is installed on the furnace wall at a plurality of stages (here, three stages) at intervals of up to 2 m. The furnace wall installation means is mounted using a suitable metal fitting or the like. The gas supply piping system 13 for supplying combustion air and inert gas to each of the ring-shaped injection pipes 11 includes an inert gas supply piping system 1.
3-1, a combustion air supply piping system 13-2, and a piping system with a flow control valve 14 provided for each ring-shaped injection pipe 11, and the flow control valve 14 provided for each piping system is provided inside the blast furnace. The mechanism is controlled by the arithmetic and control unit 10 for adjusting the gas composition.

When the top gas (CO, H ₂ ) is burned by the above apparatus, first, the gas composition of the furnace top 1 is analyzed by the top gas analyzer 7, and the gas composition falls within the explosion range shown in FIG. Or outside the explosion range. As a result, when the in-furnace gas at the furnace top is within the explosion range, the arithmetic and control unit 10 determines the ring-shaped injection pipe 11 closest to the raw material layer level 15 measured by the raw material layer level meter 6. As a method of obtaining the difference, for example, a difference between the measured raw material layer level and a known ring-shaped injection pipe level set value is determined, and a difference between the smallest and the ring-shaped injection pipe level above the raw material layer level is determined. A selection method can be used. Subsequently, the flow control valve 14 of the ring-shaped injection pipe 11 and the flow control valve 14 of the inert gas supply pipe system 13-1 of the gas supply pipe system 13 are controlled by the arithmetic and control unit 10, and the flow rate of the injection pipe is reduced. The active gas is blown until it is out of the explosion range. Then, when the composition of the combustible gas in the gas analysis value falls within the explosion range, the supply of the inert gas is stopped, and the flow control valve 14 of the combustion air supply piping system 13-2 is controlled so that the combustion from the injection pipe is performed. Supply air for use. By blowing the combustion air, the furnace top gas is spontaneously ignited.

As a result of analyzing the gas composition in the furnace by the furnace top gas analyzer 7, if the gas composition is out of the explosion range, the raw material layer level measured by the raw material layer level meter 6 in the same manner as described above. Is obtained by the arithmetic and control unit 10 and the ring-shaped injection pipe 11 is determined in the same manner as described above.
And the combustion air is blown from the injection pipe to ignite the furnace top gas.

At the time of spontaneous ignition, the flame does not blow out from the manhole and the like because the manhole 4 and the like are kept closed. The ignition of the furnace top gas is confirmed by raising the in-furnace gas thermometer 9, fluctuating the pressure of the furnace top gas pressure gauge 8, the furnace opening night vision camera 5, and the like.

[0018]

As described above, the present invention has the following effects. (1) By providing a ring-shaped injection pipe of air or an inert gas at the furnace top, it is possible to spontaneously ignite flammable gas generated from the raw material in the furnace. It becomes unnecessary. (2) By installing a plurality of ring-shaped injection pipes in the furnace height direction, the combustion air and the inert gas for dilution necessary for ignition can be supplied near the surface of the raw material layer in accordance with the raw material layer level at that time. It can be charged and the furnace top ignition operation can be performed safely and quickly. (3) The equipment is relatively simple and can be easily installed on the existing furnace top.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a plan view showing a ring-shaped injection pipe in the same device.

FIG. 3 is a side view of the same ring-shaped injection pipe.

FIG. 4 is a view showing a combustion range of a furnace top gas.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace top part of blast furnace 2 Charging hole 3 Furnace gas outlet 4 Manhole 5 Furnace mouth night vision camera 6 Raw material layer level meter 7 Furnace gas analyzer 8 Furnace gas pressure gauge 9 Furnace gas thermometer 10 Arithmetic controller Reference Signs List 11 ring-shaped injection pipe 12 introduction pipe 13 gas supply piping system 14 flow control valve 15 raw material layer level

Continued on the front page (72) Inventor Takashi Suzuki 3 Oaza Hikari, Kashima City, Ibaraki Prefecture Sumitomo Metal Industries Kashima Works, Ltd. (72) Inventor Keiji Yani 3 Oaza Hikari Kashima City, Ibaraki Prefecture Sumitomo Metal Industries Kashima Works

Claims (2)

[Claims] 1. A method for igniting flammable gas at the top of a blast furnace when the blast furnace is shut down, wherein a ring-shaped injection pipe is provided at the top of the blast furnace or at a plurality of stages in a furnace height direction, and air is supplied from the ring-shaped injection pipe. When an inert gas is injected into the blast furnace and spontaneously ignites, the arithmetic and control unit determines whether it is within the explosion range or outside the explosion range based on the analysis value of the furnace gas composition. Inert gas is blown from the ring-shaped injection pipe closest to the raw material level position until it is out of the explosion range, and when it is in the explosion range, the injection of the inert gas is stopped to blow combustion air. Starting at the beginning, when the gas composition in the blast furnace is out of the explosion range, combustion air is blown from the ring-shaped injection pipe closest to the raw material level position. 2. A furnace mouth night-vision camera for grasping the state of a raw material layer in a blast furnace, a raw material layer level meter for detecting a position of the raw material layer in the blast furnace, a furnace gas analyzer, a furnace gas pressure gauge, and a furnace inside. In a blast furnace equipped with a gas thermometer and an arithmetic and control unit for adjusting the gas composition in the blast furnace, one or more ring-shaped injection pipes are installed at the top of the blast furnace and a plurality of stages in the height direction of the blast furnace. Piping is configured to supply combustion air and inert gas to each ring-shaped injection pipe from a gas supply system with a valve,
A furnace ignition device for a blast furnace, wherein each of the flow rate control valves is controlled based on a furnace gas composition obtained by the arithmetic and control unit.