JPH089727B2 - Vertical furnace operating method and vertical furnace equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is a vertical furnace that does not increase or fluctuate the internal pressure of a furnace even when a metal raw material having poor ventilation is charged. The present invention relates to the operating method and vertical furnace equipment of.

[Conventional technology]

In a vertical furnace, a metal raw material is charged into the furnace, and an oxygen-containing gas (generally air) introduced into a wind box provided outside the furnace wall is blown into the furnace from the tuyere by the internal pressure of the wind box. It is operated so that oxygen is blown in, the coke in the furnace is burned to melt and smelt the metal raw material, and the hot metal and slag are discharged from the tap pipe and slag pipe at the bottom of the furnace. .

The outflow state of the molten pig iron and molten slag will be described in more detail with reference to FIG. 4 which is a sectional view of the lower portion of the continuous slag slagging vertical type vertical furnace as an example.

The lower end 1a of the furnace wall on the tapping gutter 2 side of the furnace body 1 is slightly lower than the lower end 1b of the furnace wall on the side of the tapping gutter 3, and the lower end 1b of the furnace wall on the side of the tapping gutter 3 is used as a reference. At the height X of the upper end 2a of the pigtail 2 and the height Y of the upper end 3a of the slag gutter 3 (these are referred to as the height of the dam), the height X is slightly lower than the height Y.
The molten pig iron 4 and molten slag 5 melted in the furnace body 1 accumulate in the lower portion of the furnace body 1, and since the specific gravity of the molten pig iron 4 is larger than that of the molten slag 5, the molten pig iron 4 is discharged from the tapping gutter 2. Further, the molten slag 5 will flow out from the slag gutter 5. In such a vertical furnace, the heights X and Y of the dams of the tap pipe 2 and the tap pipe 3 are determined as follows. Assuming that the molten iron 4 and the molten slag 5 are in the most standard condition as shown in FIG. 4 and the pressures in the furnace body 1 and the tap sluice 2 and the slag trough 3 are balanced, Is established.

First, on the side of the tap pipe 2 X × γi = S ₁ × γs + P where γi: specific weight of molten pig iron S ₁ : thickness of molten slag 5 in furnace body 1 γs: specific weight of molten slag 5 P: furnace body The gas internal pressure of 1 is established.

Similarly, on the outlet sluice 3 side, S ₂ × γs + M × γi = S ₁ + P S ₂ M = Y where S ₂ : Thickness of molten slag 5 in the outlet sluice 3 M: Hot metal in the outlet sluice 3 A thickness of 4 holds.

As described above, the dam heights X and Y of the tap gutter 2 and the tap gutter 3 in the ideal operating state, the specific weights γi, γs of the hot metal 4 and the hot metal 5, the inside of the furnace body 1 and the slag The relationship between the thicknesses S ₁ and S ₂ of the molten slag 5 in the gutter 3 and the gas internal pressure P of the furnace body 1 is shown, but in the actual operating conditions, the above equations often do not hold. Therefore, in order to continue stable operation, it is necessary to operate so that the difference between the height X and Y of the dam actually installed and the required height of the dam is small and fluctuations are minimized. During operation, the above γi, γs,
Since the fluctuations of S ₁ and S ₂ are small, the gas internal pressure P of the furnace body 1 is eventually
It is necessary to operate properly and with small fluctuations.

Conventionally, in order to satisfy the above-mentioned needs, a metal raw material used has good ventilation in a furnace. The reason is that if the ventilation of the inside of the furnace is significantly deteriorated by the metal raw material, the pressure inside the furnace becomes high by increasing the blowing pressure of the oxygen-containing gas or suppressing the exhaust of the gas after combustion, This is because the pressure balance between the side of the tappipe 2 and the tappipe 3 and the inside of the furnace main body 1 is disrupted, and the hot metal and the slag are blown out from each gutter. Therefore, according to the conventional operation method, a metal raw material that deteriorates ventilation in the furnace, for example, a granular material such as sludge, dust, scale, and clasp fine particles, or an extremely large diameter (for example, an allowable limit) (1/3 or more of furnace diameter)
However, there was a drawback that the block-shaped ones could not be used.

When such a phenomenon occurs, the pressure in the furnace body is lowered, and the amount of oxygen-containing gas blown from the tuyere is reduced.However, this reduces the amount of oxygen supplied to the furnace. As the amount of combustion coke decreases,
There was also a drawback that the dissolution rate decreased.

[Problems to be Solved by the Invention]

The present inventors have solved the above-mentioned drawbacks of the prior art,
Reproduced as dusts such as converter dust and blast furnace dust, sludge such as pickling sludge generated in pickling process, hot rolled scale produced in hot rolling process, and steelmaking raw materials such as scraps produced in the steelmaking process. Although it contains a large amount of components that can be used, if it is charged into the vertical furnace as it is, it will be necessary to effectively use the metal raw material that causes poor ventilation. Even if the pressure balance between the inside of the furnace and the taphole or tappipe is not disturbed, and the melting rate of the metal raw materials can be kept almost constant, the operation method of the vertical furnace and the vertical furnace equipment suitable for its implementation are constructed. This is an object of the present invention.

[Means for solving the problem]

As a result of various investigations by the present inventors, air and oxygen gas are used together as oxygen-containing gas, and even when a metal raw material that causes poor ventilation is used, the total amount of oxygen depends on the degree of poor ventilation. The present invention has been made by clarifying that the above problems can be solved by increasing and decreasing the respective flow rates of air and oxygen gas under conditions of keeping the amount constant and constantly maintaining the pressure inside the furnace constant. .

Conventionally, the use of so-called oxygen-enriched air in which oxygen gas is mixed with air has been tried, but the purpose is to save fuel,
Countermeasures against poor coke, energy saving, improvement of hot metal temperature and fluidity, etc. Therefore, in order to prevent the rise and fluctuation of pressure in the furnace when using metal raw materials with poor ventilation, It was not something like adjusting the flow rate according to the degree of failure.

Hereinafter, a vertical furnace operating method and a vertical furnace facility according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a system diagram of one embodiment of a vertical furnace equipment according to the present invention, FIGS. 2 (a), (b) and (c) are explanatory diagrams of an operating procedure for controlling the pressure inside the furnace, and FIG. (A), (b),
(C), (d), and (e) are explanatory views showing an example of an implementation state of the present invention.

First, a method for operating a vertical furnace according to the present invention will be described.

A vertical furnace, for example, a vertical furnace 1'of a continuous slag-removing tapping type shown in FIG. 1 is generally operated as described above. That is, a metal raw material and a raw material containing coke (not shown) are charged from a charging port 1c at the upper part of the furnace main body 1 and a wind box 6 (not shown in the vertical furnace 1'of FIG. Box 6 is the furnace body 1
The oxygen-containing gas introduced into the furnace is blown into the furnace from the tuyere by the internal pressure of the wind box 6 so that a predetermined amount of oxygen is supplied. The predetermined oxygen supply amount is determined so as to have an appropriate dissolution rate depending on the type of metal, the type of raw material and the like. The oxygen-containing gas blown into the furnace burns the coke, melts the metal raw material by the reaction heat, and while it is soluble, it separates the slag while the coke is falling and the smelted hot metal and molten metal are refined. As described above, the slag flows out from the bottom tap gutter 2 and the bottom tap gutter 3, respectively.

In the method of the present invention, air and oxygen gas are used together as the oxygen-containing gas in the operation as described above, and, importantly, at least a part of the metal raw material is a metal raw material that causes poor ventilation. The degree of poor ventilation in the furnace is judged by the internal pressure of the wind box 6 which is raised and lowered by the internal pressure of the furnace, and air and oxygen gas are mixed so that the internal pressure of the wind box 6 maintains a constant pressure. The respective flow rates to the wind box 6 are adjusted under the condition that the total flow rate of oxygen contained therein maintains the predetermined oxygen supply amount. Therefore, the air and the oxygen gas are guided to the wind box 6 via separate paths capable of individually adjusting the flow rates, and the flow rates of both of them are adjusted as described above in this separate path. In this way, by maintaining the internal pressure of the wind box 6 at a constant pressure, it is possible to prevent the internal pressure of the furnace from rising and fluctuating.

Next, the vertical furnace equipment according to the present invention, which is suitable for carrying out the above-described vertical furnace operating method, will be described with reference to FIG.

The original purpose of using the vertical furnace equipment is to charge the raw material from the upper part and blow the oxygen-containing gas from the tuyere to continuously tap the iron from the lower part.
In such a vertical furnace equipment, in the vertical furnace equipment according to the present invention, a pressure gauge 8 for measuring the internal pressure is installed in the wind box 6 communicating with the tuyere 7 of the furnace body 1. This pressure gauge 8
Is capable of transmitting a pressure signal to the control device. As a part or all of the gas pipe for guiding the oxygen-containing gas to the wind box 6, a separate route is formed from the air supply source 9 and the oxygen gas supply source 10, and the air pipe 11 and the oxygen gas pipe are provided.
Twelve are provided. In FIG. 1, the two pipes 11 and 12 are joined together in front of the wind box 6 to form a common gas pipe 12 '. The air supply source 9 and the oxygen gas supply source 10 are constantly replenished with air and oxygen gas, respectively, and are kept in a pressurized state. An air flow meter 13, an oxygen gas flow meter 14, and an electromagnetic flow rate control valve 15, respectively for each of the air pipe 11 and the oxygen gas pipe 12 that form the separate path.
16 and are installed. Like the pressure gauge 8, the air flow meter 13 and the oxygen gas flow meter 14 can also send a flow rate signal to the control device. And the pressure gauge 8, the air flow meter 13, the oxygen gas flow meter 14 and the electromagnetic flow control valves 15, 16
In order to operate in an organically related manner, the controller 17, the air pipe 11 and the regulators 18 and 19 for each oxygen gas 12 are installed. The control device 17 is a pressure gauge 8 installed in the wind box 6.
Calculates the air flow rate and the oxygen gas flow rate for maintaining the internal pressure of the wind box 6 at a constant pressure under the condition that the total oxygen flow rate of the air and the oxygen gas maintains the predetermined oxygen supply rate by receiving the pressure signal 20 from Then, the flow rate change command signals 21 and 22 are issued to the controllers 18 and 19, respectively. Each controller 18, 19 is a control device 1
The flow rate change command signals 21 and 22 from 7 and the flow rate signals 23 and 24 from the air flow meter 13 and the oxygen gas flow meter 14 are received, and an opening degree correction signal for eliminating the difference is issued. The vertical furnace equipment according to the present invention is constituted by the above-mentioned devices and the vertical furnace 1 '.

[Action]

The vertical furnace equipment according to the present invention operates as follows with the above configuration.

The wind box 6 at a certain point of the vertical furnace 1'in operation
The internal pressure of the valve matches the set pressure P ₁ set in the controller 17, the air flow rate is V _a-1 and the oxygen gas flow rate is V _o-1, and the total flow rate of these oxygen flows to the controller 17. It is assumed that the set predetermined oxygen supply amount Vto is met. If there is no change in ventilation in the furnace, the pressure gauge 8 of the wind box 6 does not move, and the control device 17 does not give any instruction.

From such a state, when the pressure measured by the pressure gauge 8 is about to exceed the set pressure P ₁ of the wind box 6 due to the use of a metal raw material that impairs ventilation, the air flow rate is set to the value shown in FIG. The controller 17 issues a command to decrease V _a-1 to V _a-2 as shown in (a) and increase the oxygen gas from V _{o- 1} to V _o-2 as shown in FIG. 2 (b). Issued to each regulator 18,19. Then, an opening degree correction signal is transmitted from each of the regulators 18 and 19 to each of the electromagnetic flow rate control valves 15 and 16 to regulate the flow rates of air and oxygen gas. That is, the internal pressure of the wind box 6 is set to the set pressure P ₁
In order to maintain the above condition, the controller 17 issues a flow rate change command to the controllers 18 and 19, and the air flow rate decreases from V _a-1 and at the same time, the oxygen gas flow rate increases from V _{o- 1} to V _o-2 . This keeps the total amount of oxygen to be fed into the furnace, that is, the sum of the amount of oxygen in the supply air and the amount of oxygen of the supply oxygen gas at a predetermined oxygen supply Vto, and reduces the dissolution rate of the metal raw material in the furnace. Prevent. Then, the total flow rate of air and oxygen gas decreases from before the adjustment, and as a result, the increase in the internal pressure of the wind box 6 (and therefore the internal pressure of the furnace) is immediately corrected and returned to the original value. If the above adjustment is insufficient or the internal pressure of the wind box 6 is about to increase due to the internal pressure of the furnace, the same control as described above is subsequently performed. In contrast to the above, when the internal pressure of the wind box 6 is about to drop below the set pressure P ₁ due to the internal pressure of the furnace, the control mechanism acts in the opposite manner to the above, and the total oxygen flow rate is adjusted to the predetermined oxygen supply Vto. The air supply amount is increased and the oxygen gas flow rate is decreased while keeping the set pressure to keep the set pressure P ₁ constant. In this way, the total flow rate of air and oxygen gas is adjusted and changed according to the ventilation of the metal raw material used,
The total oxygen flow rate and the internal pressure of the wind box 6 are shown in Fig. 2 (C).
As shown in (4), it is always constant, and the melting and refining in the furnace can always be kept stable.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to examples.

Using the equipment shown in the system diagram in FIG. 1, the plant was operated under the following conditions.

Vertical furnace inner diameter 1m Set oxygen supply amount 16.8Nm ³ / min Set wind box internal pressure (furnace internal pressure 1000mm equivalent to water column) Melt rate 7T / hour Raw coke Cast coke Metal raw material Pig iron and steel scrap Metal raw material ventilation is The loading order was good first, then bad, and finally good again. The operating condition is shown in Fig. 3 divided into each item.

The air flow rate and oxygen gas flow rate decreased according to the ventilation of the metal raw material charged as shown in Fig. 3 (b) and (c), but the total oxygen flow rate was almost as shown in Fig. 3 (d). The amount of oxygen supply is maintained at the same level as the set amount, so there is no large change in the dissolution rate as shown in (e) in the figure, and there is no large change in the wind box as shown in (b) in the figure. Therefore, the furnace pressure was the same, and no hot metal or slag was blown out from each gutter.

〔The invention's effect〕

As described above in detail, the vertical furnace operating method and the vertical furnace equipment according to the present invention use air and oxygen gas together as the oxygen-containing gas, and maintain the oxygen total flow rate thereof at a predetermined constant amount. By adjusting each flow rate below to increase or decrease the total flow rate to maintain the internal pressure of the furnace at a constant level, even if the raw material used has poor ventilation and the degree of fluctuation It is possible to keep the pressure in the furnace at a constant set value while keeping the melting rate constant. As a result, stable operation can be carried out without blowing hot metal or molten slag from the gutter, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a system diagram of one embodiment of the vertical furnace equipment according to the present invention, and FIGS. 2 (a), (b) and (c) are explanatory diagrams of an operating procedure for controlling the pressure inside the furnace, and FIG. Figure (a), (b),
(C), (D), and (E) are explanatory views showing an example of the implementation state of the present invention, and FIG. 4 is a schematic cross-sectional view of the lower portion of the vertical furnace. 1 '…… Vertical furnace 1 …… Main body 1a …… Bottom end of furnace wall on tap gutter side 1b …… Bottom end of furnace wall on tap gutter side 1c …… Inlet 2 …… Tap gutter 2a …… Top end 3 …… Debris gutter 3a …… Top end 4 …… Molten iron 5 …… Molten slag 6 …… Wind box 7 …… Tuyere 8 …… Pressure gauge 9 …… Air supply source 10 …… Oxygen gas supply source 11 …… Air Piping 12 …… Oxygen gas piping 12 ′ …… Common gas piping 13 …… Air flow meter 14 …… Oxygen gas flow meter 15,16 …… Electromagnetic flow control valve 17 …… Control device 18,19 …… Regulator 20 …… Pressure signal 21,22 …… Flow rate change command signal 23,24 …… Flow rate signal 25,26 …… Opening degree correction signal M …… The thickness of the hot metal in the slag trough P …… The gas pressure S in the furnace body ₁ …… Thickness of slag in the furnace body S ₂ …… Thickness of slag in the outlet slag V _a-1 , V _a-2 …… Air flow rate V _o-1 , V _o-2 …… Oxygen Gas flow rate Vto …… Predetermined oxygen supply amount X …… Height of the dam on the tapping gutter side Y …… Height of the dam on the tapping gutter side

Claims (2)

[Claims] 1. An oxygen-containing gas introduced into a wind box by charging metal raw materials, coke and other raw materials from the upper part of a vertical furnace, and a predetermined oxygen supply amount from the tuyere into the furnace by the internal pressure of the wind box. In order to burn the coke in the blowing furnace and continuously tap it, the metal raw material that causes poor ventilation is used at least in part, and air and oxygen gas are separately supplied as oxygen-containing gas. It is guided to the wind box through another path with adjustable flow rate, and each flow rate of air and oxygen gas is adjusted under the condition that the total flow rate of oxygen keeps the specified oxygen supply amount to maintain the internal pressure of the wind box at a constant pressure. The method for operating a vertical furnace is characterized by preventing fluctuations in the internal pressure of the furnace. 2. A vertical furnace facility in which a raw material is charged from the upper part and an oxygen-containing gas is blown from the tuyere to continuously tap the lower part, which is connected to the tuyere (7) of the furnace body (1). A pressure gauge (8) for measuring the internal pressure is installed in a wind box (6) through which the oxygen-containing gas blown into the furnace is introduced, and a part of a gas pipe for guiding the oxygen-containing gas to the wind box (6) or All are provided in separate paths from the air supply source (9) and the oxygen gas supply source (10), and each path has an electromagnetic flow rate together with an air flow meter (13) and an oxygen gas flow meter (14). Control box (15), (16) is installed, wind box (6)
In response to the pressure signal (20) from the pressure gauge (8) installed in the air conditioner, the internal pressure of the wind box (6) is kept constant under the condition that the total oxygen flow rate of air and oxygen gas maintains a predetermined oxygen supply amount. A controller (17) for calculating the air flow rate and the oxygen gas flow rate for maintaining the flow rate and issuing each flow rate change command signal (21), (22) is installed, and the control apparatus (17) is provided for each of the above paths. Flow rate change command signals (21) and (22) from the air flow meter (1
3), flow signal from oxygen gas flow meter (14) (23), (2
4) Each opening correction signal (2
Vertical furnace equipment characterized in that regulators (18), (19) for transmitting the electromagnetic flow control valves (15), (16) to the electromagnetic flow control valves (15), (5), (26) are installed.