JPH049590A - Operation control method of cokeless cupola - Google Patents

Abstract

PURPOSE:To perform an operation always at a proper air-fuel ratio by analyzing components of CO and CO2 in exhaust gas sampled from a furnace and thereafter automatically controlling a flow control means for air and fuel on real time based on the results of the analysis to operate a burner. CONSTITUTION:Exhaust gas sampled through an exhaust gas sampling tube 13 is sent to a component analysis means 14, where CO and CO2 in the exhaust gas is analyzed to obtain the contents thereof. The results of the analysis are inputted into a control means 15, where said results are compared with desirable reference contents of {CO(0-6%), CO2(10-15%)} to compute correction values. The correction values are outputted to a flow control means 16 for air and fuel to automatically control the means 16 on real time so that a burner is operated at an air-fuel ratio such that contents of CO and CO2 in the exhaust gas are within the reference contents. As a result, stability of atmosphere in the furnace is improved and oxidation of molten bath is reduced, so that metal contents can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the operation of a corkless cupola used for melting metal.

[Prior Art] For example, a coke cupola that burns coke is known as a cupola (melting furnace) used in foundries to melt metal (mainly steel thread metal).

However, when metals are melted by this type of cupola,
The precipitation of sulfur absorbed by the molten metal embrittles the metal, making it difficult to carry out complicated ductile desulfurization, for example.In addition, the sulfur mixed in the combustion products is a serious problem that pollutes the atmosphere. There are drawbacks.

Therefore, in recent years, the corkless cupola shown in FIG. 2 has been increasingly used.

Corkless cupola has a steel casing IA made of fireproof material I
A plurality of gret bars 3 are arranged horizontally at predetermined intervals inside a vertical cylindrical main body l lined with H, and these gret bars 3 hardly react chemically to the molten metal. The combustion chamber 4 supports a plurality of balls 2 made of a refractory material, and is equipped with at least one (usually a plurality of locations) combustion chamber 4 on the outside of the vertical cylindrical main body l at the lower part of the pole 2. A mixture gas of fuel 4 and air, such as natural gas, city gas, or liquefied petroleum scum, is combusted by operating the /9-9 provided at the outer end of the pole 2. is passed upward while being heated to melt metal 6 such as steel scraps and iron scraps thrown into the upper part of the pole 2 in the vertical cylindrical main body part 1.

The metal 6 melted at the top of the pole 2 is reheated by the pole 2 as it drips downward from the gap between the poles 2, and then passes through the gap between the grete pars 3 and is stored in the furnace bottom 7 in a molten state. , from the tap 8 continuously or intermittently. Further, the slag 9 is taken out from the slag outlet 10.

By using a corkless cupola configured in this way, metal embrittlement due to the precipitation of sulfur absorbed by the molten metal and complicated desulfurization of the ductile can be avoided, and the sulfur mixed in the combustion products can be used to eliminate the atmosphere. The serious drawback of contamination will also be eliminated.

[Problems to be Solved by the Invention] Incidentally, the operation of the conventional corkless cupola is controlled only by manually controlling the combustion of the burner 5 . In other words, a method is adopted in which the air and fuel flow lid adjustment, which sets the air-fuel ratio to the stoichiometric mixture ratio, is manually controlled.

In such a control method, it is easier to shift to a rich mixture or a lean mixture than to an air-fuel ratio or a stoichiometric mixture ratio, and therefore it is difficult to always ensure combustion under optimal conditions.

Furthermore, even if changes occur in the oxygen enriched amount, outlet temperature, exhaust gas composition, etc. by shifting to the rich mixture or lean mixture, there is no function to perform feedback control based on the detected values of these changes.

Therefore, the stability of the atmosphere in the furnace decreases, increasing the oxidation of the molten metal, and as a result, the melt loss of C, Si, Mn, etc. increases, making the metal components unstable, and the increased oxidation of iron causes the oxidation of the molten metal to increase. FeO increases and reduces the fluidity of the slag,
In order to ensure good fluidity, the amount of limestone, dolomite, etc. added increases, which causes problems such as increased damage to refractories by erosion, and the continuation of unsuitable combustion outside of optimal conditions. This has drawbacks such as increased operating costs.

The present invention was developed in view of these circumstances, and the burner is constantly combusted under optimal conditions, thereby improving the stability of the atmosphere in the furnace and reducing oxidation of the molten metal.
Limestone is used to stabilize the metal components by reducing erosion loss of i, Mn, etc., and to reduce the amount of FeO in the slag by suppressing the oxidation of iron, improving the fluidity of the slag and ensuring good fluidity. Achieving a reduction in the amount of additives such as dolomite, reducing damage caused by erosion of refractories, and achieving appropriate /<
- It is an object of the present invention to provide a method for controlling the operation of a corkless cupola, which is capable of reducing operating costs by continuing the combustion of the corkscrew.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention collects exhaust gas by suction from inside the furnace of a coke les cupola, and analyzes co and CO2 in the collected scum using a component analysis means. After that, the analysis results are input into the control means, and the content of CO and CO2 in the waste gas is set within a predetermined range by a control signal output from the control means based on the analysis results. 6 [Function] According to the present invention, the content of CO and CO in the exhaust gas is constantly controlled. , it can be operated by continuing burner combustion at an appropriate air-fuel ratio that can be set within a predetermined range.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic explanatory diagram showing an embodiment of a corkless cupola to which the present invention is applied. The feature of the present invention is that exhaust gas is collected by suction from inside the furnace of a corkless cupola, CO and CO2 in the collected exhaust gas are analyzed by a component analysis means, and the analysis results are inputted to a control means and analyzed. In order to set the content of CO and CO2 in the exhaust gas within a predetermined range by a control signal output from the control means based on the result, the air and fuel flow rate adjustment means automatically controls the appropriate air-fuel ratio in real time, Regarding the configuration for burning the burner 5, other members and their configurations other than these are the same as in the conventional example.

In FIG. 1, parts corresponding to those in FIG. 2 are given the same reference numerals, and their explanations are omitted. In FIG. For example, the material input port IC of the vertical main body 1 is inserted into the furnace by penetrating the furnace wall at the bottom in order to suction and collect the exhaust gas. Here, C in the exhaust gas
The content is determined by analyzing O and CO2.

The analysis results analyzed by the component analysis means 14 are converted into electrical signals and then input to the control means 15, where the content rates of CO and CO2 based on the analysis results and the preferred reference content rate ( CO (0-6%), CO
; (10-15%)) to find the correction value,
This correction value is output as a control signal to the air and fuel flow rate adjustment means 16 attached to the burner 5, and the flow rate adjustment means 16 is automatically controlled in real time to reduce the amount of carbon in the exhaust gas.
The eight-gas 5 is combusted at an air-fuel ratio in which the O and CO2 contents are set within the range of the standard content.

With such a configuration, even if the content of CO and CO2 in the exhaust gas deviates from the above-mentioned standard content range due to the shift of the sheet metal and air-fuel ratio to a rich or lean mixture, the The air-fuel ratio is set to an air-fuel ratio that can be corrected within the range of the standard content, and this air-fuel ratio allows /Hena 5 to be combusted under optimal conditions, improving the stability of the furnace atmosphere and preventing oxidation of the molten metal. As a result, melting loss of C, Sf, Mn, etc. can be suppressed and stability of metal components can be ensured.

In addition, since the amount of FeO in the slag is reduced by reducing the oxidation of iron, the fluidity of the slag is improved and the amount of limestone, dolomite, etc. added can be reduced, making it possible to reduce damage caused by erosion of refractories. The synergistic effect of these can reduce operating costs.

[Effects of the Invention] Although the present invention is configured as described above, it produces the following effects.

In other words, the CO and CO2 contents in the exhaust gas can be constantly set within a predetermined range, allowing operation to continue with proper burner combustion, which improves the stability of the furnace atmosphere and reduces oxidation of the molten metal. In addition to stabilizing the metal components by reducing the erosion loss of , Mn, etc., the amount of FeO in the slag is reduced by suppressing the oxidation of iron, improving the fluidity of the slag, and adding limestone and dolomite to ensure fluidity. It is possible to achieve a reduction in the amount of additives such as, to reduce damage caused by melting and damage to refractories, and to realize a reduction in operating costs due to the synergistic effect of these.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of a corkless cupola to which the present invention is applied, and FIG. 2 is a schematic explanatory diagram of a conventional corkless cupola. 5...Burner, 13...Exhaust gas sampling pipe, 14...
Exhaust gas component analysis means, 15...control means, 16...
・Air and fuel flow rate adjustment means. Figure 1 5-Bar 1- 13-God 1 Sue Guidance f
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Claims (1)

[Claims] (1) Exhaust gas is sucked and collected from inside the furnace of Corcle Cupola, and CO and CO_2 in the collected exhaust gas are analyzed by component analysis means.The analysis results are input to the control means, and the control means is based on the analysis results. In order to set the content of CO and CO_2 in the exhaust gas within a predetermined range by a control signal output from the burner, the burner is combusted at an appropriate air-fuel ratio by automatically controlling the air and fuel flow rate adjustment means in real time. A method for controlling the operation of corkless cupola.