KR100815701B1 - Method for forecasting sharp drop of pressure of melter-gasifier and method for controlling the pressure in ironmaking process using non-coking and fine ore - Google Patents

Abstract

A method for predicting sharp drop of pressure of a melter-gasifier and a method for controlling the pressure in a molten iron manufacturing process using non-coking coal and fine iron ores are provided to operate pressure of the melter-gasifier always stably by predicting sharp drop of pressure of the melter gasifier through sharp drop of pressure of an excess gas recovery tank and controlling the supply amount of gas(reduction gas) supplied into a reduction furnace when pressure of the recovery tank drops sharply. In a molten iron manufacturing process for manufacturing molten irons by comprising fluidized-bed furnaces, a reduction furnace, and a melter-gasifier, and by using non-coking coal and fine iron ores, a method for predicting sharp drop of pressure of the melter-gasifier in a molten iron manufacturing process using non-coking coal and fine iron ores comprises the steps of: measuring in real-time an internal pressure of a gas storage tank for recovering and storing excess gas generated in the melter-gasifier; and predicting a sharp drop of the internal pressure of the melter-gasifier when the internal pressure of the gas storage tank measured in real-time drops sharply. In a molten iron manufacturing process for manufacturing molten irons by comprising fluidized-bed furnaces, a reduction furnace, and a melter-gasifier, and by using non-coking coal and fine iron ores, a method for controlling pressure of a melter-gasifier in a molten iron manufacturing process using non-coking coal and fine iron ores comprises the steps of: measuring in real-time an internal pressure of a gas storage tank for recovering and storing excess gas generated in the melter-gasifier; predicting a sharp drop of the internal pressure of the melter-gasifier when the internal pressure of the gas storage tank measured in real-time drops to a set pressure or lower; and controlling an internal pressure of the melter-gasifier by controlling the amount of reduction gas supplied into the melter-gasifier or/and the reduction furnace when the sharp drop of the internal pressure of the melter-gasifier is predicted.

Description

Method for Forecasting Sharp Drop of Pressure of Melter-Gasifier and Method for Controlling The Pressure in Ironmaking Process Using Non-coking and Fine Ore}

1 is a process diagram mainly showing the exhaust gas system of the molten iron manufacturing process using the coal and powdered iron ore according to the present invention

2 is a graph showing the pressure in the furnace as a process run

3 is a graph showing the correlation between the pressure drop in the melting furnace and the pressure drop in the buffer tank

Explanation of symbols on the main parts of the drawings

10 .... exhaust gas recovery line 20 .... gas storage tank (buffer tank)

110 .... Flow furnace 120 .... Reduction furnace

140 .... Melting Furnace G1, G2, G3, G4 .... Gas Circulation Line

Ge1, Ge2 .... exhaust gas line

The present invention relates to a melting furnace pressure drop prediction method and a melting furnace pressure control method of the molten iron manufacturing process to predict that the pressure of the melting furnace drops sharply in the molten iron manufacturing process using ordinary coal and fine iron ore, the exhaust gas recovery in more detail In the process of manufacturing molten iron using ordinary coal and ferrous iron ore, which predicts the pressure drop in the tank, and when the pressure in the recovery tank decreases, the gas (reduced gas) supplied to the reduction furnace is controlled to ensure stable operation of the furnace pressure. The present invention relates to a melting furnace pressure drop prediction method and a melting furnace pressure control method.

A typical blast furnace method among known molten iron manufacturing methods requires a raw material preliminary treatment facility such as a coke production facility, and there is a problem that a huge cost is required for the construction of such ancillary facilities.

In addition, such a blast furnace method is a huge cost to the environmental pollution prevention equipment for the treatment of environmental pollutants generated during the operation of the coke production equipment.

Therefore, a process for manufacturing molten iron using plain coal and iron ore, which directly uses molten iron as a fuel and a reducing agent and directly uses molten iron ore, which accounts for more than 80% of the world's ore production, is used as an iron source. For example, FINEX process is known.

For example, the main equipment of the FINEX process consists of a flow reduction furnace consisting of multiple stages and a reduction furnace, and a melting furnace in which a coal filling layer is formed.

Therefore, the ore at room temperature charged in the uppermost reactor (flow furnace) is heated at high temperatures and reduced at least 90% by contacting the hot reducing gas supplied from the furnace through the multistage flow furnaces and the reduction furnace. At the same time, the reduced spectroscopy is charged into the molten furnace in which the coal bed is formed and melted in the coal bed therein, thereby being converted to molten iron and discharged from the furnace.

In addition, the smelting furnace is continuously supplied with the bulk of coal from the upper part of the furnace to form a coal filling layer of a certain height in the furnace, oxygen through a plurality of air holes formed in the bottom of the outer wall of the filling layer into the filling layer. Coal is charged and the coal in the packed bed is burned and the combustion gas is converted into a high temperature reducing air stream as it rises up the packed bed and circulated and supplied to the flow path and the reducing furnace.

However, the high temperature reducing gas generated in such a melting furnace and supplied to the flow furnace and the reducing furnace is generated by combustion and gasification of ordinary coal, and the amount of generation varies considerably depending on the properties and operation abnormalities of the raw coal.

For example, depending on the operation of the furnace, the fluctuation amount of the hot reducing gas amount is about 20 to 50% of the average gas production amount in severe cases, and such extreme gas fluctuation may occur in a considerably short time.

As a result, the fluctuation of the gas flow rate leads to a sudden increase or decrease in the amount of hot reducing gas circulated and supplied to the flow furnace, the reduction furnace and the melting furnace, and such a rapid change in the gas flow rate, in particular, the sudden decrease in the gas flow rate is caused by the flow furnace or the reduction furnace. It can be developed into a fluidized bed collapse that disrupts the ore fluidized bed within.

In addition, the amount of gas circulating or the pressure drop, which plays a role of keeping the internal pressure of the melting furnace constant, causes a considerable problem in operation which makes the operation of the melting furnace unstable.

However, it is not easy to predict in advance the pressure drop of such a melting furnace.

For example, although the internal pressure of the melting furnace can be grasped numerically as shown in FIG. 2, it is not easy to predict when the internal pressure of the melting furnace will drop, and such a melting pressure prediction method has not been proposed.

Moreover, no method of predicting the pressure drop in the furnace and controlling the pressure inside the furnace has been proposed.

Accordingly, the Applicant of the present invention recognizes that the change in the internal pressure of the furnace is related to the rapid fluctuation of the exhaust gas discharge, and grasps the pressure phenomenon of the tank for recovering the exhaust gas and predicts the internal pressure drop of the melting furnace based on the method. It was proposed a method of controlling the furnace pressure.

The present invention has been made in order to improve the conventional problems as described above, the object of the present invention is to recognize the pressure drop of the gas storage tank for the recovery of the exhaust gas discharged from the melting furnace to predict the pressure drop of the melting furnace and The present invention provides a method for predicting the pressure drop of a melting furnace in a molten iron manufacturing process using iron ore.

In addition, another object of the present invention is to predict the pressure drop of the melting furnace, and based on this control the pressure of the gas (reduction gas) supplied to the reduction furnace affecting the pressure of the furnace before the pressure of the melting furnace is reduced by controlling the furnace pressure The purpose of the present invention is to provide a melting furnace pressure control method for molten iron manufacturing process using ordinary coal and ferrous iron ore to ensure stable operation of the furnace.

As an embodiment of the technical aspect to achieve the above object, the present invention, in the molten iron manufacturing process for producing molten iron using ordinary coal and fine iron ore, including a flow furnace, a reducing furnace and a melting furnace, Real-time measurement of the internal pressure of the gas storage tank for recovering and storing the exhaust gas generated from the gas; And,
Predicting the internal pressure drop of the melting furnace when the internal pressure drop of the gas storage tank is measured in real time;
It provides a method for predicting the pressure drop of the melting furnace of the molten iron manufacturing process using a coal and fine iron ore composed.

Alternatively, the present invention as another embodiment of the technical aspect, in the molten iron manufacturing process for producing molten iron using a coal and fine iron ore, including a flow furnace, a reducing furnace and a melting furnace, recovering the exhaust gas generated in the melting furnace Measuring the internal pressure of the gas storage tank to be stored in real time; And,
Predicting the internal pressure drop of the melting furnace when the internal pressure of the gas storage tank to be measured in real time falls below a set pressure;
It provides a method for predicting the pressure drop of the melting furnace of the molten iron manufacturing process using a coal and fine iron ore composed.

On the other hand, as another technical aspect of the present invention, in the molten iron manufacturing process for manufacturing molten iron using ordinary coal and fine iron ore, including a flow furnace, a reduction furnace and a melting furnace, gas storage for recovering and storing the exhaust gas generated in the melting furnace Measuring the internal pressure of the tank in real time;
Predicting the internal pressure drop of the melting furnace when the internal pressure of the gas storage tank to be measured in real time falls below a set pressure; And,
Controlling the internal pressure of the melting furnace by adjusting the amount of reducing gas supplied to any one or both of the melting furnace and the reducing furnace when the internal pressure drop of the melting furnace is predicted;
It provides a melting furnace pressure control method of the molten iron manufacturing process using a coal and powdered iron ore configured to include.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

However, in the following drawings, the apparatus for manufacturing molten iron is indicated by the reference numeral of 100 units, the equipment related to the exhaust gas circulation system is indicated by the reference numeral of 10 units, and the gas circulation or the exhaust gas line is indicated by the first letter 'G'.

In addition, FIG. 1 illustrates a flue gas system of a FINEX process as a representative process for manufacturing molten iron using direct coal and powdered iron ore.

However, before describing the melting pressure drop prediction method and the pressure control method of the present invention, the exhaust gas recovery system associated with the pressure drop prediction of the melting furnace will be described.

First, as shown in Figure 1, in the molten iron manufacturing process consisting of a multi-stage flow path 110, a flow reduction path 130 of the reduction furnace 120, and a melting furnace 140 is formed with a coal filling layer, the top stage The ore at room temperature continuously charged into the reactor (flow furnace) of the reactor is heated and heated by contacting with the high-temperature reducing gas supplied from the furnace 140 while passing through the flow furnaces 110 and the reduction furnace 120 in sequence. At the same time, the above-described reduction is converted into high-temperature reduction spectroscopy, and the reduced spectroscopy is made of molten iron by continuously charging in the melting furnace 140 in which the coal bed is formed and melting in the coal bed therein.

In addition, the smelting furnace 140 is continuously supplied with coarse coal from the upper part of the furnace to form a coal filling layer having a predetermined height in the furnace, and a plurality of tuyere formed at the bottom of the outer wall of the filling layer into the filling layer. Oxygen is blown in through the coal in the packed bed and the combustion gas is converted into a high temperature reducing air stream while rising the packed bed and discharged from the melting furnace 140 to be supplied to the flow path 110 and the reducing furnace 120.

That is, the reducing gas discharged from the gas discharge pipe 142 of the melting furnace 140 passes through the cyclone 150 to each melting furnace, the reducing furnace and the flow side gas circulation lines G1 (G2) and G3 ('gas Through each conduit).

However, as described above, the amount of high-temperature reducing gas supplied to the flow furnace (G2 line), reduction furnace (G1 line), and melting furnace (G3 line) is rapidly changed in a short time.

Therefore, such a rapid decrease or increase in the amount of reducing gas makes it difficult to temporarily collapse the ore fluidized beds in the flow furnace 110 and the reduction furnace 120 or to maintain a constant internal pressure of the furnace, making the operation of the furnace unstable. Therefore, it is necessary to secure a stable fluidized bed through recovery of reducing gas or to maintain stable operation of the melting furnace.

At this time, a part of the exhaust gas discharged from the melting furnace 140 is discharged to the melting furnace side exhaust gas line Ge1 through the pressure control valve 154, and circulated to the reduction furnace 120 and the flow path 110. Control the rapid fluctuations of the reducing gas.

That is, while discharging the change in pressure or flow rate to the furnace side exhaust gas line (Ge1), only a constant flow rate and pressure are supplied to the flow path 110 and the reduction furnace 120.

However, in this case, there is a case that the reducing gas to reduce the iron ore in the actual operation is not supplied stably.

Therefore, as shown in Figure 1, the unnecessary CO ₂ in the reduction through the passage 110, gas circulation line (G4), a branch from the exhaust gas line (Ge2) side of a portion of the exhaust gas into the flow discharged from the CO ₂ remover It circulates and supplies to the melting furnace gas discharge pipe 142 in the state removed in 166.

However, through this, additional gas supplementation is not sufficient, so the state of insufficient reducing gas circulated in the reduction furnace or the flow passage is not solved, so that the exhaust gas of the furnace side exhaust gas line (Ge1) is recovered and stored without being used when necessary. How to do it was added.

In this case, reference numerals 152 and 162 in FIG. 1 (which are also applied to FIGS. 2 and 3 below) are cooling facilities for lowering the exhaust gas temperature in each of the exhaust gas lines Ge1 and Ge2 in the melting furnace side and the flow furnace side, and 154 is a pressure. Control valve, and 164 is a flow control valve.

That is, as shown in FIG. 1, an exhaust gas recovery line 10 is connected to the melting furnace side exhaust gas line Ge1 and circulates and supplies exhaust gas to the melting gas discharge pipe 142, and the exhaust gas is introduced into the exhaust gas recovery line 10. A gas storage tank 20 to be stored, that is, a buffer tank is installed to store exhaust gas therein to compensate for the shortage of the reducing gas described above.

At this time, preferably, the compressor 30 is installed on the downstream side of the exhaust gas recovery line of the gas storage tank 20. Such a compressor serves to supply high pressure when circulating the exhaust gas from the tank to the melting furnace side. do.

On the other hand, the buffer tank of the gas storage tank 20 of the present invention, since the low-pressure exhaust gas is stored intact in the melting furnace side exhaust gas line (Ge1), it is possible to build and use a low-pressure low-capacity tank.

In addition, between the downstream side of the compressor 30 in the exhaust gas recovery line 10 and the buffer tank may be connected to the high-pressure gas back-supply pipe 40 for supplying the high-pressure gas back to the tank to fine-tune the gas discharge from the buffer tank And, such a high-pressure gas back supply pipe 40 may be provided with a control valve 42.

Meanwhile, as described above, the exhaust gas recovery line 10 is branched from the flow path side exhaust gas line Ge2 and connected to a circulation line G4 connected to the furnace gas discharge pipe 142, and the recovered exhaust gas is stored in a gas. Melting furnace (G3 line), flow furnace (G1 line) and reduction furnace (G2 line), in which the high pressure flue gas stored in the tank 20 and compressed by the compressor is connected via the gas discharge pipe 142 and the cyclone 150. To each of the circulation.

Therefore, the fluidized bed collapse in the flow furnace or the reduction furnace is prevented, and the internal pressure of the melting furnace is kept constant.

On the other hand, as shown in Figure 1, the downstream of the compressor of the exhaust gas recovery line 10 is provided with at least one control valve 14 for controlling the circulation supply of the high-pressure gas, the gas storage tank of the exhaust gas recovery line 10 The control valve 12 is also provided on the upstream side.

Therefore, hereinafter, the method for predicting the melting furnace pressure drop in the molten iron manufacturing process using the general coal and the iron ore of the present invention will be described based on the exhaust gas circulation system of the molten iron manufacturing process described so far.

First, as shown in FIG. 1, in the melting furnace pressure drop prediction of the present invention, the gas provided in the exhaust gas recovery line 10 branched from the melting furnace side exhaust gas line Ge1 recovering the exhaust gas generated in the melting furnace 140. The characteristic is that when the internal pressure of the storage tank 20, that is, the buffer tank, decreases sharply, for example, when the pressure falls below the set pressure, the internal pressure of the melting furnace drops sharply.

Meanwhile, the reason for predicting the internal pressure drop of the melting furnace in connection with the internal pressure state of the gas storage tank 20 of the exhaust gas recovery line is as follows.

For example, FIG. 2 graphically illustrates the melting pressure drop in the melting furnace, and FIG. 3 graphically illustrates the pressure drop correlation between the melting furnace 140 and the gas storage tank 20 serving as the buffer tank.

2 and 3 are data obtained during the actual operation of the molten iron manufacturing process, for example, the Finex process, which is being constructed and operated by the present applicant.

That is, as shown in Figure 2, the internal pressure of the melting furnace is affected by the fluctuation of the gas flow rate, the gas flow rate or pressure is kept constant as shown in Figure 2 through the exhaust gas circulation system of Figure 1, but the pressure drops sharply Phenomenon occurs ('P' in FIG. 2).

However, when the internal pressure state of the gas storage tank 20 is connected at the 'P' point that is the minimum pressure value in the pressure graph of FIG. 2, that is, the point at which the pressure decreases, the graph as shown in FIG. 3 may be obtained.

For example, as shown in FIG. 3, the internal pressure of the gas storage tank 20 before the predetermined time 'T' (for example, about 30 minutes based on the graph) at the point 'P1' where the internal pressure of the melting furnace starts to drop sharply is' It begins to descend at P2 'point.

And, based on 'P1', the internal pressure of the melting furnace decreases from the normal pressure or the internal pressure of the buffer tank to about 1.3 bar from 2.0 bar.

Next, it can be seen that the lowest value of the furnace pressure and the pressure lowest value of the buffer tank occur at about the same time.

Accordingly, as shown in FIG. 3, when the storage pressure of the gas storage tank 20, that is, the buffer tank is about 2.0 to about 1.1 bar is about 1.3 to 1.3, the internal pressure drop of the gas storage tank is recognized and the internal pressure of the melting furnace is also reduced. It can be predicted to drop sharply.

As a result, the present invention has not been possible to predict when the internal pressure of the melting furnace will drop so far, but by simply using the existing equipment to implement this, through this to prevent the operation instability caused by the pressure drop in the melting furnace Will make it possible.

In this case, as shown in Figure 1, the buffer tank of the gas storage tank 20 is provided with a pressure measuring means 50, that is, a pressure sensor at one point, the pressure sensor is connected to the facility control unit 60 In this case, the internal pressure measurement value of the gas storage tank can be grasped in real time.

For example, when a display (not shown) such as a monitor is connected to the control unit 60, the facility operator can grasp the internal pressure of the buffer tank in real time.

On the other hand, the set pressure of the gas storage tank 20 is a reference pressure that predicts that the pressure of the melting furnace will drop rapidly when the pressure is lower than the reference pressure, based on Figure 3 buffer based on the gas storage tank 20 The pressure may be 65% of the gas receiving pressure of the tank.

For example, as shown in Figs. 1 and 3, when the receiving pressure of the gas storage tank 20 is 2 bar, the pressure of the gas storage tank 20, which is an approximately buffer tank at P1 when the melting furnace pressure starts to drop sharply, If it is below 1.3 bar (or 1.1 bar), it is assumed that it is the set pressure, and if it is below it, the internal pressure of the furnace will drop rapidly.

Of course, this evidence is based on data obtained during actual operations, as described earlier.

At this time, if the set pressure of the buffer tank, which is the gas storage tank 20, is higher than 65% of the tank accommodation pressure, an incorrect prediction may be made that the internal pressure of the melting furnace will drop sharply even in a normal operating environment. It is preferable to determine the set pressure based on data such as a graph.

Next, by predicting that the internal pressure of the melting furnace will drop sharply, the pressure inside the melting furnace can be controlled.

For example, as shown in FIG. 1, when the internal pressure of the gas storage tank 20 storing the recovered flue gas is lower than the set pressure, it is predicted that the pressure of the melting furnace will drop sharply, and the melting furnace 140 is previously prepared. And controlling the internal pressure of the melting furnace 140 by adjusting the amount of reducing gas supplied to any one or both of the reducing furnace 120.

At this time, as shown in Figure 1, in connection with the control unit 60 and the furnace gas discharge pipe 142 to which the pressure sensor, which is the internal pressure measuring means 50 of the gas storage tank 20 that is the buffer tank is connected to reduce the furnace and the reducing gas It operates in conjunction with the control valves 70 and 72 provided in the gas circulation lines G3 and G1 supplied to the furnace.

Therefore, when the internal pressure of the gas storage tank 20 is measured by the pressure sensor in real time and transmitted to the controller 60, the controller 60 continuously compares the preset pressure with the preset pressure, and determines that the pressure is less than or equal to the preset pressure. In response to determining that the internal pressure of the melting furnace is to be sharply reduced, the control unit 60 linked to the amount of reducing gas supplied to the reduction furnace (G1 line) controls the operation of the control valve 70 so that the internal pressure of the melting furnace is not suddenly reduced.

For example, when the amount of reducing gas supplied to the reduction furnace 120 is normally about 45,000 Nm 3 / h, the gas reduction is reduced to about 29,000 Nm 3 / h to control the internal pressure of the melting furnace not to drop sharply.

As a result, in the melting furnace pressure drop prediction method and the melting furnace pressure control method of the molten iron manufacturing process using the coal and powdered iron ore of the present invention, it is possible to simply predict the internal pressure drop of the melting furnace while using the existing molten iron manufacturing equipment, and through this, the melting furnace. It keeps the internal pressure stable.

That is, it is possible to increase the productivity of the molten iron manufacturing process for manufacturing molten iron using ordinary coal and iron ore by the stable operation of the melting furnace.

As described above, according to the method of predicting the pressure drop of the melting furnace in the molten iron manufacturing process using the ordinary coal and the fine iron ore, the pressure drop of the gas storage tank for recovering the exhaust gas discharged after the pressure control of the furnace is recognized in advance. Makes it possible to predict.

In addition, according to the furnace pressure control method of the present invention, it is possible to stably implement the furnace pressure operation by controlling the gas (reduction gas) supply amount to the reduction furnace in advance before the furnace pressure drop.

As a result, the present invention provides an excellent effect of stably maintaining the operation of the melting furnace of the molten iron manufacturing process using ordinary coal and fine iron ore to improve the operating productivity.

While the invention has been shown and described in connection with specific embodiments so far, it will be appreciated that the invention can be varied and modified without departing from the spirit or scope of the invention as set forth in the claims below. It will be appreciated that those skilled in the art can easily know.

Claims (8)

In the molten iron manufacturing process for producing molten iron using ordinary coal and powdered iron ore, including a flow furnace, a reducing furnace and a melting furnace, Measuring the internal pressure of a gas storage tank for recovering and storing the exhaust gas generated in the melting furnace in real time; And, Predicting the internal pressure drop of the melting furnace when the internal pressure drop of the gas storage tank is measured in real time; Melting furnace pressure drop prediction method of the molten iron manufacturing process using a general coal and iron ore, characterized in that configured to include. In the molten iron manufacturing process for producing molten iron using ordinary coal and powdered iron ore, including a flow furnace, a reducing furnace and a melting furnace, Measuring the internal pressure of a gas storage tank for recovering and storing the exhaust gas generated in the melting furnace in real time; And, Predicting the internal pressure drop of the melting furnace when the internal pressure of the gas storage tank to be measured in real time falls below a set pressure; Melting furnace pressure drop prediction method of the molten iron manufacturing process using a general coal and iron ore, characterized in that configured to include. The method of claim 2, wherein the set pressure in the internal pressure prediction step of the melting furnace is 65% of the gas containing pressure of the gas storage tank. The internal pressure of the gas storage tank is measured in real time by the pressure measuring means provided in the gas storage tank connected with a control unit in a real-time internal pressure measurement of the gas storage tank. Prediction method for melting furnace pressure drop in molten iron manufacturing process using plain coal and iron ore. According to any one of claims 1 to 3, wherein the gas storage tank is installed in the exhaust gas recovery line branched from the furnace side exhaust gas line, the exhaust gas is without pressure fluctuations through the furnace side exhaust gas and exhaust gas recovery line. Melting furnace pressure drop prediction method of the molten iron manufacturing process using ordinary coal and iron ore, characterized in that stored in the gas storage tank. In the molten iron manufacturing process for producing molten iron using ordinary coal and powdered iron ore, including a flow furnace, a reducing furnace and a melting furnace, Measuring the internal pressure of a gas storage tank for recovering and storing the exhaust gas generated in the melting furnace in real time; Predicting the internal pressure drop of the melting furnace when the internal pressure of the gas storage tank to be measured in real time falls below a set pressure; And, Controlling the internal pressure of the melting furnace by adjusting the amount of reducing gas supplied to any one or both of the melting furnace and the reducing furnace when the internal pressure drop of the melting furnace is predicted; Melting furnace pressure control method of the molten iron manufacturing process using a coal and powdered iron ore characterized in that it comprises a. According to claim 6, In the real-time measurement of the internal pressure of the gas storage tank, it is determined whether the pressure measuring means provided in the gas storage tank is connected to the control unit and the internal pressure of the gas storage tank is lowered below the set pressure while real-time measurement in real time And the set pressure is 65% of the gas storage pressure of the gas storage tank. 8. The control valve of claim 7, wherein the control unit connected to the pressure measuring means provided in the gas storage tank is connected to the gas discharge pipe connected to the melting furnace to supply the reducing gas to the melting furnace and the reducing furnace. Melting furnace pressure control method of the molten iron manufacturing process using ordinary coal and ferrous ore, characterized in that for controlling the amount of reducing gas supplied to any one or both of the melting furnace and the reducing furnace when the internal pressure of the gas storage tank suddenly reduced.

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