JP2000265171A - Method for switching passage of exhaust gas of coke oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of unburned combustibles and soot even when temporarily a draft pressure is suddenly reduced by switching an exhaust gas passage of a coke oven by enabling to carry out switching of the exhaust gas passage after bringing a fuel flow rate to the coke oven to a low flow rate in advance. SOLUTION: In the exhaust gas passage 4 of a coke oven, in which a passage through a dust collector and a passage through a bypass are installed in parallel to be mutually switched in the exhaust gas passage 4 from the combustion chamber 3 of the coke oven to a chimney, the exhaust gas passage 4 is switched after bringing a fuel flow rate to the coke oven to a low flow rate in advance in switching from the passage through the dust collector to the passage through the bypass. In the exhaust gas passage 4, a passage directly connected to the chimney 7 through a damper 1 on the side of the chimney and a passage connected to the chimney through a damper 2 on the side of the dust collector and the collector 6 are installed in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for switching an exhaust gas path of a coke oven.

[0002]

2. Description of the Related Art Improving the environment in a coke oven is an important issue, and one of the issues is to prevent black smoke in combustion exhaust gas from being emitted to the outside. This black smoke is generated when coal powder in the carbonization chamber enters the combustion chamber due to furnace body deterioration of the coke oven and is discharged from the chimney together with the combustion exhaust gas without completely burning.

As a countermeasure for removing the coal powder that causes the black smoke, a dust collector has been put into practical use in the middle of an exhaust gas path (flue) of the combustion exhaust gas, and the effect has been improved. The combustion air of the coke oven is sucked by the draft pressure of the chimney, but the draft pressure is controlled so that the combustion air flows in accordance with the fuel flow rate determined by the operating conditions of the coke oven. The occurrence is always controlled to a minimum.

[0004]

However, during maintenance of the dust collector, for example, in the case of a bag filter type dust collector, for example, replacement of a filter medium, the combustion exhaust gas is temporarily discharged directly from the chimney without passing through the dust collector. It is necessary to switch to the path to be performed. After the maintenance, switching to the path via the dust collector is performed again.

This switching is usually performed by opening and closing dampers 1 and 2 provided on both paths as shown in FIG. For example, when switching from the path passing through the dust collector 6 to the path discharging directly to the chimney 7, the damper 1 on the chimney side is used.
Is opened and the damper 2 on the dust collector side is closed. However, when switching the exhaust gas path of the coke oven, the draft pressure suddenly drops at the moment when the damper on the switching side is opened, and as a result, the amount of combustion air is temporarily insufficient, and unburned components may be generated. is there. As a result, there is a problem that soot is generated in a remarkable case, and is discharged from the chimney as black smoke as it is.

The present invention provides a method for switching the exhaust gas path of a coke oven, which can suppress the generation of black smoke even when the path is switched.

[0007]

According to the present invention, the fuel supplied to the coke oven is limited in advance in order to minimize the unburned state and suppress the generation of soot even when the draft pressure is rapidly reduced as described above. This is because the fuel flow to the coke oven has been set to a low flow rate before switching the exhaust gas path.

That is, the present invention relates to a coke oven exhaust gas path in which a path passing through a dust collector and a bypass path are juxtaposed in an exhaust gas path from a combustion chamber of a coke oven to a chimney. A method for switching an exhaust gas path of a coke oven, wherein the exhaust gas path is switched after the fuel flow rate to the coke oven is reduced beforehand when switching from the to the bypass path.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for switching an exhaust gas path of a coke oven according to the present invention will be described with reference to the flowchart of FIG.
Combustion air 10 and fuel 8 are externally supplied to the combustion chamber 3 of the coke oven. The amount of fuel 8 supplied is controlled by a fuel control valve 9.

Exhaust gas after combustion in the combustion chamber 3 is discharged from a chimney 7 via a flue 4. The exhaust gas path includes two paths, a path directly connected to the chimney via the chimney side damper 1, and a path connected to the chimney 7 via the dust collector side damper 2 and the dust collector 6. As described above, these paths are switched during maintenance of the dust collector and the like.

Here, a draft pressure measuring device 5 is installed in the flue, and when a dust collector 6 is used, the draft pressure obtained by the draft pressure measuring device 5 is set to a predetermined value. The opening degree of the dust collector-side damper 2 is adjusted in advance.
On the other hand, when the exhaust gas path is switched for maintenance and inspection of the dust collector 6, a fuel flow rate at which the draft pressure does not increase is determined in advance based on the measurement value of the draft pressure measuring device 6.
The fuel control valve 9 is controlled so as to achieve this flow rate.

The present invention is characterized in that when switching the exhaust gas path, the fuel flow rate is previously reduced to a low flow rate, and then the switching is performed. By doing so, even if the draft pressure temporarily drops suddenly due to the switching and the flow rate of the combustion air drops, the unburned fuel and soot can be prevented from occurring.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. The coke oven used in this example was a 90-piece coke oven, and the coke production was 70 t / H. As the fuel, a mixed gas adjusted to 1200 kcal / Nm ³ by mixing blast furnace gas and coke oven gas was used. The gas flow rate required for the above coke oven is 32,000 Nm ³ / H, and a draft pressure of −30 mmH ₂₀ is required to flow a predetermined amount of air required for complete combustion. .

At this time, for maintenance of the dust collector, switching to a path not passing through the dust collector was performed. At that time, the draft pressure at the moment of opening the chimney side damper 1 will jump to -5mmH ₂ 0. Therefore, by applying the method of switching the exhaust gas path of the coke oven of the present invention, the gas flow rate is set to 10,000 Nm in advance.
^{When the} chimney side damper 1 was opened after decreasing to ³ / H, there was no generation of unburned matter or soot. After that, the dust collector side damper 2 was closed, but no problem occurred.

On the other hand, for comparison, the gas flow rate was 32,000 Nm
^{Although the} damper was switched while keeping the pressure at ³ / H, a large amount of unburned fuel (CO, H ₂ ) and soot were generated due to the shortage of combustion air, and black smoke was also generated from the chimney. As described above, by the method of the present invention, by reducing the gas flow rate before switching the damper, it was possible to prevent the generation of unburned components and soot at the time of switching.

It should be noted that the extent to which the gas flow rate is reduced depends on the characteristics of each furnace. However, if the gas flow rate is reduced to about 1/3, it can be confirmed that soot does not occur even when the draft pressure becomes about 1/9. Therefore, it is preferable to reduce the flow rate to 1/3 or less of the normal operation.

[0017]

According to the present invention, even if the draft pressure is temporarily reduced suddenly when the exhaust gas path is switched, the generation of unburned fuel and soot can be suppressed, and black smoke is generated from the chimney. Also gone.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for switching an exhaust gas path of a coke oven according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chimney side damper 2 Dust collector side damper 3 Combustion chamber (of a coke oven) 4 Exhaust gas path (flue) 5 Draft pressure measuring device (draft pressure gauge) 6 Dust collector 7 Chimney 8 Fuel 9 Fuel control valve 10 Air

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Takeshita 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba F-term in Kawasaki Steel Corporation Chiba Works (Reference) 4H012 GA05 GB00

Claims (1)

[Claims] 1. A coke oven exhaust gas path in which an exhaust gas path from a combustion chamber of a coke oven to a chimney is arranged in a switchable manner between a path passing through a dust collector and a bypass path, from a path passing through the dust collector to a bypass path. A method of switching the exhaust gas path of a coke oven, wherein the switching of the exhaust gas path is performed after the fuel flow to the coke oven is reduced to a low flow rate in advance.