WO2013108512A1

WO2013108512A1 - Converter gas recovery device and seal gas blowing operation method

Info

Publication number: WO2013108512A1
Application number: PCT/JP2012/081882
Authority: WO
Inventors: 織田　剛; 稲葉　岳志; 慎哉杉浦
Original assignee: 株式会社神戸製鋼所
Priority date: 2012-01-19
Filing date: 2012-12-10
Publication date: 2013-07-25

Abstract

A converter gas recovery device can reliably replace a portion open to the atmosphere between a converter throat and the converter gas recovery device with an inert gas atmosphere by introducing a large amount of inert gas into the portion open to the atmosphere, and recovers converter gas generated in a converter blowing process from a recovery hood, the converter gas recovery device being characterized in that blowing portions (7, 8) for seal gas having the inert gas as a main component are provided toward an air stream from the converter front side to the converter throat in a converter space between a dust collection duct disposed on the converter front side in plan view and a converter throat center.

Description

Converter gas recovery device and seal gas injection operation method

The present invention relates to a converter gas recovery device that recovers a converter gas mainly composed of CO generated in a converter blowing process, and a method of blowing a seal gas supplied to a recovery hood of the converter gas recovery device. is there.

CO gas generated in large quantities in the converter blowing process has good combustibility and usually has a latent heat of about 2,000 Kcal / nm ^3, so fuel gas for boilers, rolling mills, lime firing furnaces, etc. It is used as.

In the converter gas recovery apparatus that recovers the CO gas through the recovery hood, it is necessary to prevent the leakage of CO gas or the inflow of outside air by reducing the gap between the furnace port of the converter and the recovery hood as much as possible. A skirt is provided. And the seal structure by seal gas (inert gas) is formed between the furnace port and the skirt part (for example, refer patent document 1).

In addition, a cover part is provided so as to cover the skirt part from the surroundings, and an air supply pipe and an intake pipe for supplying seal gas to the CO gas are connected to the cover part, and the pressure near the collection hood exceeds the atmospheric pressure. Sometimes the inside of the cover is adjusted to less than atmospheric pressure, and when the pressure near the collection hood is less than atmospheric pressure, the CO gas is efficiently recovered while adjusting the pressure inside the cover to exceed atmospheric pressure. A gas recovery method has also been proposed (see, for example, Patent Document 2).

Also known is a sealing method in which CO ₂ is used as the sealing gas when the gap between the furnace port of the converter and the recovery hood is sealed with a sealing gas, and the sealing gas is actively sucked by the converter gas recovery device. (See, for example, Patent Document 3).

As described above, a method for recovering the converter gas while making the atmosphere between the furnace port and the recovery hood an inert gas atmosphere or adjusting the pressure in the cover has been proposed. It is intended to blow a seal gas such as nitrogen gas or carbon dioxide gas into a narrow atmosphere opening portion between the collection hood and the air.

JP 59-222514 A JP-A-63-317612 JP-A-56-127721

However, since the seal gas required for actual blowing requires a volume flow of about 0.25 times the volume flow of the CO gas generated from the converter, the diameter of the seal gas supply pipe for that purpose is required. Therefore, the size of about 1/2 of the furnace diameter is required.

It is practically impossible to provide such a large-diameter pipe in a narrow space between the furnace port and the recovery hood. In consideration of raising and lowering the skirt portion by operating the hydraulic cylinder, the seal gas supply pipe is neither a size that can be attached to such a skirt portion nor a weight.

The vicinity of the furnace opening is also called spitting, where the liquid melt from the converter frequently scatters and falls, and the recovery hood closes as the scattered liquid melt adheres closer to the furnace throat. It becomes easy to do.

Furthermore, the cost of producing a normal temperature sealing gas that is about 0.25 times the volume flow rate of nitrogen or carbon dioxide with respect to the volume flow of CO gas at 1,300 to 1,500 ° C. will increase. For the above reasons, sealing with a sealing gas is not actually performed at all because it is still more expensive than the profit obtained from the converter gas recovery amount.

In addition, when sealing is performed using sealing gas, in order to prevent N _{2 in the} outside air from being mixed into the recovered converter gas, sealing must be performed by introducing an excessive sealing gas. However, if sealing is performed with a large amount of sealing gas over a long period of time, for example, CO ₂ has a higher specific gravity than air, so that the sealing gas is trapped on the work floor and ventilation is indispensable.

As described above, in the method of sealing by blowing a seal gas, even if the seal gas is CO ₂ , N ₂ , or other gas, there is no danger of oxygen deficiency as long as it does not contain oxygen at a concentration suitable for breathing. Sex comes. However, no safe seal gas blowing operation method that can avoid the above-mentioned danger has been proposed so far.

The present invention has been made in consideration of the problems in the conventional converter gas recovery apparatus as described above, and the first object is to provide a large amount of air in the open part between the converter furnace port and the recovery hood. An object of the present invention is to provide a converter gas recovery apparatus that can introduce an inert gas and can reliably replace the above-described open-at-air portion with an inert gas atmosphere.

In addition, the second object of the present invention is to prevent a decrease in oxygen concentration in the working environment even when an excessive inert gas is blown as a seal gas or when a situation occurs in which the seal gas is not sucked into the recovery hood. An object of the present invention is to provide a sealing gas blowing operation method capable of performing the above.

The present invention has a first mode related to the converter gas recovery device and a second mode related to the seal gas injection operation method.

The first aspect of the present invention is a converter gas recovery apparatus that recovers the converter gas generated in the converter blowing process through a recovery hood.
An inert gas is mainly supplied to the converter space between the dust collection duct arranged on the front side of the furnace when viewed from the plane and the center of the converter furnace port, toward the air flow from the front side of the furnace to the converter furnace port. It is a converter gas recovery device provided with a blowing portion of a sealing gas as a component.

In the first embodiment of the present invention, the sealing gas is blown from the blowing portion along the tilt axis of the converter as viewed from above, and the blowing target of the sealing gas is closer to the furnace front side than the converter furnace port. Preferably it is directed.

Moreover, it is preferable to arrange a pair of the blowing portions in a state of being symmetrically opposed with respect to the converter.

Also, the blowing port of the blowing section can be opened on the left and right wall surfaces that house the converter.

Further, the blowing port of the blowing section can be opened from the left and right wall surfaces accommodating the converter to the tip of a duct extending along the tilt axis of the converter.

In the second mode of the present invention, when recovering the converter gas from the recovery hood, in the seal gas injection operation method of sealing the gap between the converter furnace port and the recovery hood with a seal gas,
Detect the change in the seal gas flow during converter gas recovery, or obtain the dust collection duct suction flow rate relative to the seal gas supply flow rate,
When the flow of the seal gas changes or when the dust collection duct suction flow rate with respect to the seal gas supply flow rate falls below a predetermined value, the supply amount of the seal gas is reduced or the supply of the seal gas is stopped. This is a seal gas blowing operation method.

The change in the flow of the seal gas means, for example, a case where the flow direction of the seal gas flows backward from the inside to the outside with the heat insulating plate of the converter as a boundary.

In the second embodiment of the present invention, the change in the flow of the seal gas can be detected by attaching a wind direction sensor to the internal observation window of the heat insulating plate installed on the furnace front side of the converter.

The change in the flow of the sealing gas can also be detected by attaching a wind direction sensor to the back side gap of the heat insulating plate installed on the front side of the converter.

Also, the dust collection duct suction flow rate is obtained by converting the internal pressure of the dust collection duct into a flow rate, and when the ratio of the dust collection duct suction flow rate to the seal gas supply flow rate falls below a threshold value, the seal gas By adjusting the gate valve of the supply path, the supply amount of the seal gas can be stopped by decreasing the amount of the seal gas supplied until the threshold value or more can be maintained, or by closing the shut-off valve of the seal gas supply path.

In addition, a timer is started when a seal gas supply start command is issued, and the seal gas supply path shut-off valve is turned off when the next seal gas supply start command is not given until the predetermined time has elapsed. It can be closed and the supply of the sealing gas can be stopped.

In the first and second embodiments, the seal gas is nitrogen gas that is by-produced when oxygen used for blowing the converter is separated from air or nitrogen that contains impurities such as oxygen slightly. Gas can be used.

According to the converter gas recovery device of the present invention, a large amount of seal gas is introduced into the converter space using a large pipe, and the air-released portion between the converter furnace port and the converter gas recovery device is reliably undisturbed. It has the advantage that it can be replaced with an active gas atmosphere.

Also, there is an advantage that the maintenance cost can be suppressed because it is hardly damaged by spitting from the converter.

According to the sealing gas blowing operation method according to the present invention, when excessive inert gas is blown as the sealing gas, or when a situation occurs in which the sealing gas is not sucked into the recovery hood, the sealing gas is blown. It has the advantage that it can be controlled safely and reliably.

(a) is an air flow diagram in the converter and converter gas recovery device according to the present invention, and (b) is an air flow diagram in a state in which the heat insulating plate and the dust collecting duct are removed. It is explanatory drawing which shows the structure of the blow-down type blowing duct in a converter gas recovery apparatus. It is the graph which showed the substitution efficiency by the blowing duct of an opposing blowing system. It is the side view which showed the example of arrangement | positioning of the blowing duct. It is the graph which showed the substitution efficiency at the time of combining various blowing ducts. (a) is a gas flow diagram when an extended blowing duct is applied, (b) is an analysis image of a flow velocity contour and a flow vector in a horizontal plane, and (c) is an analysis image of an inert gas concentration distribution. (a) is a gas flow diagram in the case of applying a flush blow duct, (b) is an analysis image of a flow velocity contour and a flow vector in a horizontal plane, and (c) is an analysis image of an inert gas concentration distribution. (a) is a gas flow diagram when the left window is open and a plane blow-in duct is applied, (b) is an analysis image of the flow velocity contour and the flow vector in the horizontal plane, and (c) is an analysis image of the inert gas concentration distribution. is there. It is the graph which showed the relationship between the blowing gas flow rate at the time of applying the blowing duct of this invention, and substitution efficiency. (a) is a perspective view of the converter equipment model used for the sealing gas blowing operation method concerning the present invention, and (b) is a perspective view of the converter and recovery hood in the converter equipment. It is explanatory drawing which shows the 1st measurement position of the tuft attached to the converter equipment model of FIG. It is explanatory drawing which shows the 2nd measurement position of the tuft attached to the converter equipment model of FIG. It is explanatory drawing which shows the 3rd measurement position of the tuft attached to the converter equipment model of FIG. It is explanatory drawing which shows the 4th measurement position of the tuft attached to the converter equipment model of FIG. It is a 1st graph which shows the relationship between a dust collection flow volume and the oxygen concentration in a working environment. It is a 2nd graph which shows the relationship between a dust collection flow rate and the oxygen concentration in a working environment. It is a 3rd graph which shows the relationship between a dust collection flow volume and the oxygen concentration in a working environment. It is the system | schematic schematic of the converter equipment to which the sealing gas blowing operation method of this invention is applied. It is an external view of the ultrasonic wind direction wind speed sensor used for the sealing gas blowing operation method of this invention. It is explanatory drawing which shows the attachment position of the ultrasonic wind direction wind speed sensor shown in FIG.

The converter equipment to which the present invention is applied includes a converter configured to be tiltable, ancillary equipment provided around the converter, for example, an oxygen gas blowing lance, a measuring sub lance, a converter tilting device, and a converter A recovery hood for recovering gas is provided, and these converter facilities are installed in a building not shown.

Opening and closing door-type heat shields are installed on the front side of the furnace in the building, and dust collection ducts are installed in the building on the left and right sides of the converter, on the left and right sides of the furnace, and around the recovery hood. ing.

In the present invention, among such converter facilities, a model of the main converter and converter gas recovery device is manufactured on a 1/20 scale, and numerical analysis and investigation are conducted to investigate the state of air flow in the converter space. A model experiment was conducted. As a result, it was discovered that there was an air flow from the front of the furnace toward the furnace port of the converter.

Conventionally, an air flow containing 21% oxygen is collected from the recovery hood of the converter gas recovery device together with the converter gas, so that combustion of oxygen in the atmosphere and CO gas, which is the main component of the converter gas, is performed. Reaction 2CO + O ₂ → 2CO ₂
Was changed to CO _2, and a part of the CO gas was burned and lost in the converter gas recovery device.

On the other hand, in the converter gas recovery device of the present invention, a place away from the gap portion (atmosphere release portion) between the furnace port and the recovery hood in the converter gas recovery device, specifically, the furnace front side (hot metal equipment) Release the sealing gas consisting of inert gas toward the wide space on the inlet side and place the sealing gas on the flow of air from the front side of the furnace to the furnace port as described above to create an inert gas atmosphere. It is possible to replace with. Thereby, it is also possible to blow seal gas from a position where there is little spitting damage.

Hereinafter, a converter gas recovery apparatus according to the present invention will be described in detail based on the embodiments shown in the drawings.
[1] Converter gas recovery device [1.1] Seal gas Seal gas, which has a volumetric flow rate about 0.25 times the volumetric flow rate of the converter gas, separates oxygen used for converter blowing from air. Use low-purity waste nitrogen gas produced as a by-product.

深 Usually, a cryogenic air separation device is used to produce oxygen, but the generated pure nitrogen is used in large quantities at each factory in the steelworks, so there is almost no surplus. However, about 3% of oxygen and waste nitrogen gas containing moisture up to the saturation state are released into the atmosphere without being used.

In a general cryogenic air separation device, pure oxygen, pure nitrogen, pure argon, and waste nitrogen are produced at a ratio of 20%: 20%: 1%: 59%, respectively, and 20% pure oxygen is converted. When used for blowing in a furnace,
2CO + O ₂ → 2CO
As a result of this reaction, CO gas having twice the number of moles of oxygen is generated from the converter.

Therefore, when viewed from the air separation ratio, about 40% of CO gas is generated.

From the density ratio of the normal temperature CO gas to the high temperature CO gas of 1,300 to 1,500 ° C., the volume of about 230% is seen in the state of 1,300 to 1,500 ° C. from the above air separation ratio. If a normal temperature sealing gas having a volume 0.25 times larger than that is required, about 58% of the sealing gas is required.

As explained in the above air separation ratio, waste nitrogen is produced as a by-product at a ratio of 59%. Therefore, when this waste nitrogen is used as a seal gas, it is possible to recover the converter gas at substantially no production cost. Become.

Moreover, pure oxygen is required at the time of converter blowing, and waste nitrogen is also required for the inert gas atmosphere at the same time as converter blowing, so only the blower that sends nitrogen is used. Although necessary, it is very convenient without the need for other devices.

[1.2] Air flow As described above, there is a flow of air (outside air) from the front side of the furnace toward the furnace port.

Fig.1 (a) shows the air flow diagram analyzed about the converter and the converter gas recovery device using the 1/20 scale converter equipment model, and Fig.1 (b) shows the heat insulation plate from Fig.1 (a). The air flow figure in the state which removed the dust collection duct is shown.

In both figures, the furnace port 1a of the converter 1 and the recovery hood 2 of the converter gas recovery device face each other, and a skirt portion 3 is provided around the recovery hood 2.

In addition, the said skirt part 3 is comprised by the four hydraulic cylinders 3a arrange | positioned at equal intervals on the circumference so that raising / lowering is possible. Further, a heat insulating plate 4 is disposed on the furnace front side of the converter 1, and the heat insulating plate 4 is provided with two windows 4a for monitoring the blowing state. In the figure,

reference numerals

5 and 5 denote dust collection ducts disposed on the furnace back side and the furnace right side.

In the above configuration, when recovering the converter gas (LDG) generated from the converter 1, the converter gas is recovered while blowing a seal gas into the atmosphere opening portion between the furnace port 1 a and the recovery hood 2.

Recovering 75% of the entrained air flow into the hood 2 (in the figure, see the arrow F ₁₎ flows into the converter space through the window portion 4a of the heat insulating board 4, the remaining 25% of the air flow (Fig. in, see arrow F ₂₎ is flowed through the gap or clearance between the heat insulating plate 4 on the slag carriage orbit the furnace front. In addition, the air flow caught in the collection | recovery hood 2 from the furnace back side without a clearance gap was not confirmed.

Interestingly, air is not caught in the collection hood 2 over the entire circumference 360 ° of the skirt portion 3, and air is caught from a specific range of ± 45 ° in the front direction of the furnace, and is further caught. Most of the airflow is passing through the window 4a.

When the two windows 4a shown in FIG. 1 (a) are open, 75% of the air flow passes through the windows 4a, and either the right or left window is open. In some cases, 50% air flow is passing.

Therefore, it is presumed that the sealing gas can be efficiently blown if the sealing gas (in this embodiment, waste nitrogen gas) is put on the air flow F ₁ that is drawn from the furnace front side and flows into the recovery hood 2.

[1.3] Configuration of Seal Gas Blow Unit [1.3.1] Blow Down Method In the drawings described below, the same components as in FIG.

As shown in FIG. 2, a furnace duct 1a is provided by providing a blow duct 6 having a shape cut obliquely toward the front edge of the furnace opening, and blowing down the sealing gas at a low flow rate of about 4 m / s from the blow opening 6a. About 94% of the air caught in the gap between the hood and the recovery hood 2 can be replaced with seal gas (waste nitrogen gas).

Further, as described above, since there is an air flow from the front side of the furnace to the furnace port, the blowing direction of the seal gas is not directed to the center of the furnace port, but the center of the furnace port 1a like the front edge of the furnace port. It must be directed to the front side of the furnace. However, such an arrangement of the blowing duct 6 can obtain the highest replacement efficiency, but receives the radiant heat from the charged hot metal when the converter 1 is tilted forward and the hot metal is charged. There is a problem of being exposed to high temperatures. Therefore, for practical use, it is necessary to take heat measures such as making the blow duct 6 into a heat resistant structure.

The blowing duct 6 functions as a sealing gas blowing section mainly composed of an inert gas.

[1.3.2] Opposed blowing method A pair of seal gas blowing ducts are guided through the side wall surfaces of the building into the converter space, and the blowing ports are made to face each other.

As shown in the graph of FIG. 3 and FIG. 4, the B type in which the inlet is arranged on the building wall surface between the dust collection duct in front of the furnace and the center of the furnace mouth has an inert gas (nitrogen) flow rate / involvement flow rate ratio. Compared with the A type, C type, and D type, which have high inlets at other positions, the highest replacement efficiency is achieved with a small seal gas flow rate.

The A type has a seal gas blowing port arranged directly under the furnace pre-dust collection duct, and the B type has a blow port arranged on the furnace front side between the pre-furnace dust collection duct and the furnace port center. The type C and the type C are those in which the inlet is arranged at the center of the furnace port, and the type D is the one on the back side of the furnace and the inlet is arranged rearward from the center of the furnace port. In addition, all the heights of the blowing inlet are set to the vicinity of the furnace opening height.

As shown in the graph of FIG. 5, even if the combination of the B type and another type is selected, the B type alone can still achieve high replacement efficiency with a small seal gas flow rate.

This can also be confirmed from the analysis result of the velocity vector and the inert gas concentration distribution in the B type shown in FIGS. In each figure, (a) is a flow diagram of the gas (air / seal gas) to the recovery hood, (b) is an analysis image of the flow velocity contour and the flow velocity vector in the horizontal plane, and (c) is the inert gas concentration distribution. It is an analysis image.

FIG. 6 shows that two windows (see

windows

4a and 4a in FIG. 1) are opened and extended blowing ducts 7 and 8 (the blowing duct is extended from the building wall surface into the converter space so that the blowing ports 7a and 8a protrude 2 m. The analysis results when using the above are shown.

Fig. 7 shows the analysis results when using a flush inlet duct with the two windows open (the inlet of the duct is flush with the wall of the building).

Fig. 8 shows the analysis results when only the left window is open and the flush blow duct is used.

Note that the extended blowing ducts 7 and 8 and the flush blowing duct function as a sealing gas blowing portion mainly containing an inert gas.

As shown in each of FIGS. 6 to 8, in the case of the B type, the seal gas rides on the air flow from the front side of the furnace toward the furnace port and is sucked into the recovery hood 2.

In this way, the target for blowing out the seal gas from the extension blow ducts 7 and 8 and the flush blow duct is not aimed at the furnace opening, but from the furnace opening in anticipation of getting on the air flow from the furnace front side to the furnace opening. Also aimed at the front of the furnace.

Also, each duct is provided along the tilting axis of the converter as viewed from the plane, and a pair is arranged in a state of being symmetrically opposed with the converter 1 as the center when viewed from the front.

Also, it is particularly efficient to make the collision position of the seal gas blown from both sides of the converter 1 immediately before the furnace port, and to match the flow velocity of the seal gas blown from the left and right extended blow ducts 7 and 8.

Note that the extended blowing ducts 7 and 8 can be blown without penetrating the building wall surface by arranging, for example, a crank-shaped duct in the converter space even if the building wall surface cannot be opposed to each other. The ports 7a and 8a can be made to face each other, and a replacement effect equivalent to that of the flush outlet duct can be obtained.

Incidentally, in the A type shown in FIG. 4, the injected seal gas was sucked from the dust collecting duct in front of the furnace and did not flow toward the furnace port. In the C type, the position of the injection port is closest to the furnace port, and the furnace port is on the extended line in the direction of blowing out the seal gas. As a result of the flow, the blown seal gas was flowed to the back of the furnace, resulting in removal of the furnace port.

In addition, the D type in which the blowing port was arranged on the most back side of the furnace was only replaced with about 10% of the inert gas.

Fig. 9 is a graph showing the relationship between the flow rate of the seal gas and the replacement efficiency in the extended blowing duct (extending the 2m duct from the wall surface) and the flush blowing duct (no duct outlet), and the horizontal axis below the graph is inactive. The gas flow rate / involved flow rate ratio is shown, the horizontal axis on the graph shows the flow rate of blown inert gas (m ³ / min), and the vertical axis shows the replacement efficiency (%).

As shown in the graph, suction is performed by blowing a seal gas (waste nitrogen gas) at a flow rate 1.3 to 1.7 times the outside air (intake flow rate) sucked into the converter gas recovery device. 80 to 90% of the outside air (of course, normally air containing oxygen) can be replaced with an inert gas. Further, if a seal gas having a flow rate of 2.0 times is blown, 95% of the outside air can be replaced with an inert gas.

Therefore, in order to obtain high replacement efficiency with a small seal gas flow rate, it is necessary to use an extended blow duct to bring the seal gas blow port closer to the furnace port, and when the seal gas blow amount is increased. Since the replacement efficiency increases, there is no need to provide an extended blowing duct, and the blowing port may be provided flush with the wall surface of the building.

According to the converter gas recovery apparatus having the above-described configuration, a large amount of seal gas can be obtained just by providing a blower for supplying an inert gas at a low pressure from the oxygen factory to the converter factory in the same manner as supplying oxygen for converter blowing. Can be led to a wide converter space via a large pipe, and the air release portion between the furnace port and the recovery hood can be effectively replaced with an inert gas atmosphere from a position away from the furnace port.

Moreover, there is an advantage that maintenance costs can be suppressed because there is almost no damage caused by spitting.

When the gap between the furnace port and the recovery hood is in an atmospheric atmosphere, about 10 to 15% of the CO gas generated in the converter is lost due to the combustion reaction with oxygen contained in the atmosphere. By applying the furnace gas recovery device, the lost CO gas can be reduced to 3-4%. As a result, the converter gas recovery amount and the heat generation amount are increased by 8 to 13% compared to the current CO gas recovery amount.

[2] Seal gas blowing operation method Next, the sealing gas blowing operation method will be described with reference to the drawings. In addition, in the following figure, about the same component as FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

In FIG. 10, assuming that the converter gas generated from the converter 1 is recovered, a seal gas (inert gas) is blown into the atmosphere opening portion between the furnace port 1 a and the recovery hood 2. .

In the converter equipment model, a tuft (blown flow for visualizing the flow direction) was attached to the gap portion of the shielding wall surrounding the converter, and the gas flow passing through the gap portion was observed.

[2.1] Measurement position by tuft The measurement positions by the tuft are shown in FIGS.

FIG. 11 shows the left and right windows (see a and b in the figure) provided on the furnace front open / close door heat shield as the first measurement position.

FIG. 12 shows the back of the heat insulating plate (see c in the figure) and the left and right side wall inspection windows (see e in the figure) as the second measurement position.

FIG. 13 shows, as the third measurement position, a gap between the furnace front floor and the converter body (see d in the figure) and a gap between the furnace side floor and the converter body (see g in the figure).

FIG. 14 shows a furnace door window (see f in the figure) provided on the shield wall on the furnace side as the fourth measurement position.

While observing the movement of the tufts at the first to fourth measurement positions, increase the inert gas flow rate (m ³ / h) blown as seal gas, and from the converter side (inside the building) to the outside of the converter ( The inert gas flow rate (m ³ / h) when the wind direction changed toward the working space (outside the building) was determined.

If the flow rate ratio of the dust collection flow rate to the inert gas flow rate at this time is taken, the flow rate ratio becomes almost constant regardless of the absolute values of the inert gas flow rate and the dust collection flow rate.

Next, the situation when the wind direction changes from the converter side toward the working space outside the converter will be described.

[2.2] Observation Results The change in the wind direction is the direction in which the flow that was stably sucked into the converter side (inward) suddenly goes from the converter side to the work space outside the converter from a certain flow rate condition ( The flow that has been stably sucked into the converter does not change so as to be stably blown out (outward), but the tuft direction alternates inward and outward in a short cycle from a certain flow rate condition. If the flow rate of the inert gas is increased, the air is stably blown outward.

In this test to determine the conditions for the inert gas to start a back flow, the minimum inert gas flow rate was obtained when the tuft was alternately switched between inward and outward, even if the direction of the tuft was slight. .

Table 1 shows the test results expressed as the ratio of the dust collection flow rate to the inert gas flow rate.

The symbols a to g in Table 1 correspond to the measurement positions a to g shown in FIGS.

However, in Table 1, a and b are both windows of the heat insulating plate, a is a case where the windows of both of the heat insulating plates are open, and b is a case where the window of the heat insulating plate on one side is open. To do.

As can be seen from the ratio of the minimum pre-furnace dust collection flow rate / inert gas flow rate when the tuft shows a reverse flow, the ratio of the minimum pre-furnace dust collection flow rate / inert gas flow rate at the window of the heat insulating plate is 4 .B is 4.06 in the same manner as in b. When only one side of the window portion of the heat insulating plate is opened, backflow is less likely to occur than when both window portions are opened.

Thus, the ratio of the minimum pre-reactor dust collection flow rate / inert gas flow rate shown in Table 1 indicates that blowout tends to occur in order from the top of Table 1.

Therefore, in order to capture the sign that the inert gas flows backward at the beginning, it is optimal to always perform wind direction measurement and visual observation at the position of the window portion of the heat insulating plate (see a and b). In addition, it is preferable to always perform visual observation by measuring the wind direction and blowing in the gap (see c) on the back side of the heat insulating plate.

Further, as described above, when the inert gas flow rate (seal gas supply flow rate) when the wind direction changes from the converter side toward the working space outside the converter, the inert gas flow rate at that time is obtained. Since the ratio of the dust collection flow rate (dust collection duct suction flow rate) is almost constant regardless of the absolute value of the inert gas flow rate and the dust collection flow rate, the collection rate of a certain ratio (ratio) with respect to the inert gas flow rate is used. Ensuring the dust flow rate is the essence of safety measures.

15 to 17 are graphs obtained by measuring the relationship between the ratio of the pre-furnace dust collection flow rate to the inert gas flow rate and the average oxygen concentration at the measurement position.

In each graph, the horizontal axis represents the ratio of the pre-furnace dust collection flow rate / inert gas flow rate, and the vertical axis represents the average oxygen concentration (%).

The graph of FIG. 15 is about the left and right window portions of the heat insulating plate, the graph of FIG. 16 is the gap portion between the right side of the heat insulating plate and the left heat insulating plate, and the graph of FIG. 17 is the back side of the left heat insulating plate and the right heat insulating plate. The relationship between the flow rate ratio and the oxygen concentration is shown for each gap.

Judging from these graphs, if the pre-reactor dust collection duct flow rate near the inert gas blowing device is 4.1 times or more than the inert gas flow rate to be blown, the inert gas flows from the converter side to the work floor side. It can be seen that no so-called backflow occurs.

It can be seen that securing the dust collection flow rate in this way is important in the seal gas blowing operation. Therefore, when a decrease in the dust collection flow rate is detected and the dust collection flow rate is reduced, the inert gas blowing flow rate can be lowered or the inert gas blowing can be stopped in order to blow the seal gas safely. It becomes an effective means.

[2.3] Application to Actual Converter Equipment FIG. 18 shows a system schematic diagram of the converter equipment to which the seal gas blowing operation method of the present invention is applied.

In the figure, a recovery hood 2 is provided facing the furnace port 1a of the converter 1 in an upright state, and the recovery hood 2 is connected to a dust collector 9 via a duct 2a.

When performing oxygen blowing, oxygen separated from raw material air in the cryogenic air separation device 10 is passed through an oxygen compressor 11 and an oxygen tank 12 provided in order from the upstream side of the oxygen supply path L1. Then, the oxygen lance 13 is supplied.

Further, from the cryogenic air separation device 10, waste nitrogen gas having a low purity, which is by-produced when oxygen is separated from air, is taken out for sealing gas, and is upstream of the sealing gas supply path L2. Are supplied as seal gas to the blow-in duct 18 through a seal gas compressor 14, a seal gas tank 15, a shut-off valve 16, and a gate valve 17 provided in order.

The blowing duct 18 is disposed in the vicinity of the furnace port 1a and the recovery hood 2, and is substituted with an inert gas atmosphere by blowing a seal gas into an air opening portion of the gap.

The shutoff valve 16 and the gate valve 17 are controlled to be opened and closed by a control unit 19 that performs a blowing operation, and the gate valve 17 can adjust the supply amount of the seal gas. With this, the sealing gas can be supplied or stopped.

[2.4] Seal gas blowing operation method [2.4.1] First sealing gas blowing operation method Attaching to the window of the furnace front side openable door type heat insulating plate and the back of the furnace front side openable door type heat insulating plate An ultrasonic wind sensor is used as an anemometer.

Ultrasonic wind direction wind speed sensor has extremely fast follow-up to wind direction changes compared to weathercock-type anemometers, and because the inertial mass that moves when the wind direction changes in the measuring device is zero, it responds to changes in wind direction with virtually zero time constant There is an advantage that you can.

Therefore, from the situation where the wind flutters in a few Hz with a fluttering pattern, it is possible to capture the signs of the balloon sufficiently following the fast fluctuation of several hundred Hz.

FIG. 19 shows a specific example of the ultrasonic wind direction wind speed sensor 20.

In the present embodiment, an ultrasonic wind direction sensor SE-8371UM manufactured by Senecom Co., Ltd. was used. The specifications are wind speed range: 0 to 75 m / S, resolution: 0.1 m / s, wind direction range: 0 to 360 °.

Note that the wind direction signal information and the wind speed signal information output from the ultrasonic wind direction wind speed sensor 20 are transmitted to a control system in the cab via a cable (not shown) and processed.

FIG. 20 is an explanatory diagram showing the mounting position of the ultrasonic wind direction wind speed sensor 20.

In the figure, the openable door-type heat shield 21 on the front side of the furnace is provided with a left window portion 21a and a right window portion 21b, and above the left window portion 21a and the right window portion 21b (see symbol h), respectively. The ultrasonic wind direction wind speed sensor 20 having the above configuration is installed.

As described above, the ultrasonic wind direction wind speed sensor 20 is attached to the windows (the left window 21a and the right window 21b) of the furnace front side openable door type heat insulating plate 21 so that the wind direction is from the converter side to the outside of the converter. When it is detected that the direction has been changed to the direction of the incoming crane, the control unit 19 uses this as a trigger to notify an alarm and adjust the gate valve 17 (see FIG. 18) in the seal gas supply path L2 to be closed. Then, the supply amount of the seal gas is reduced. Alternatively, the shutoff valve 16 is closed to stop the supply of the seal gas itself. Thereby, the injection of the seal gas can be controlled safely and reliably.

Moreover, although the ultrasonic wind direction wind speed sensor 20 was installed in the window part of the furnace front side openable door type heat insulating plate in the above embodiment, as described above, the gap portion behind the furnace front side openable door type heat insulating plate 21 is provided. In addition, since the sign of the blowout can be detected first, the ultrasonic wind direction wind speed sensor 20 can be installed behind the furnace front side openable door type heat shield 21.

[2.4.2] Second sealing gas blowing operation method Next, instead of the ultrasonic wind direction wind speed sensor 20, the supply of the sealing gas is controlled based on changes in the flow rate of the dust collection duct and the pressure inside the duct. A method will be described.

The flow rate of the dust collection duct can be measured with a flow meter, but in this embodiment, the differential pressure generated between the upstream and downstream of the dust collection duct arranged in the vertical direction is measured as information on the duct internal pressure that can be converted into the flow rate. The measured value is converted into a flow rate.

There are many measurement methods such as multipoint pitot tube measurement, multipoint hot-wire anemometer measurement, orifice flowmeter measurement, etc., for measuring the flow rate in the dust collection duct. However, due to the large amount of dust collection dust, all pressure holes in the Pitot tube are blocked, dust in the hot-wire anemometer easily adheres to the filament, increasing measurement errors. There is a high possibility of dust accumulation.

Therefore, in the present embodiment, a technique is adopted in which the pressure difference between the upstream and downstream of the dust collection duct portion flowing in the vertical direction with very little risk of dust accumulation is measured and converted into the flow rate of the dust collection duct.

The pressure difference ΔP between the upstream and downstream ducts is: A: duct cross-sectional area, D: duct equivalent diameter, L: duct length, ρ: dust collection air density, U: dust collection air duct average flow velocity, Q: dust collection air When the deposition flow rate = AU is used, it is expressed by the following formula (1).

In equation (1), λ is a proportionality constant (friction loss coefficient) determined by the roughness of the duct surface.

¡Since the actual duct has irregularities etc., the pressure loss mechanism is not only friction but also pressure loss due to vortex generation due to duct cross section change.

Since the effect of the vortex generation can be considered to be proportional to the square of the flow velocity as in the equation (1), the proportionality constant λ here indicates the effect of combining both pressure loss due to friction and vortex generation. Take it as a proportionality constant.

Thus, based on the flow meter that measures the flow rate of the dust collection duct and the information on the internal pressure of the dust collection duct that can be converted into the flow rate, the flow rate ratio of the dust collection duct flow rate to the inert gas flow rate is obtained. When the pressure drops below a predetermined threshold value, the control unit 19 (see FIG. 18) notifies a warning and adjusts the seal valve in a direction to close the gate valve 17 until the threshold value can be maintained. Reduce the supply amount. Alternatively, the shutoff valve 16 of the seal gas supply path L2 is closed to stop the supply of the seal gas. Thereby, the injection of the seal gas can be controlled safely and reliably.

The threshold value is determined to be “4.1” based on the graph showing the relationship between the dust collection flow rate and the oxygen concentration in the work environment shown in FIG. 15, FIG. 16, and FIG.

[2.4.3] Third Seal Gas Injection Operation Method The third seal gas injection operation method is an operation method that takes into account a failure of the measuring instrument.

When a large-scale disaster occurs, the signal information from the ultrasonic wind direction sensor 20 and the signal information from the dust collection duct flowmeter drop off from the normal measurement position with normal values due to a failure of the measuring instrument. It is assumed that it will fall into the abnormal measurement state.

In order to take safety measures even in such a situation or an unexpected situation, it is preferable to perform control so that the sealing gas blowing is automatically stopped.

Specifically, an operator who performs operations such as starting / stopping the blowing process in the converter and adjusting the oxygen flow rate always gives instructions to start and continue the injection of seal gas at regular intervals. This is an operation method in which the control unit 19 stops the injection of the seal gas unless the button operation is performed.

It is more preferable to stop blowing the seal gas not only to close the shutoff valve 16 but also to substantially eliminate the ability to send the seal gas by shutting off the power supply to the seal gas compressor 14. Even if the injection of the seal gas is stopped, only the recovery amount of the converter gas is reduced, and there is no safety problem.

In the third sealing gas blowing operation method, the operation is performed so that the blowing operation worker of the converter continues the sealing gas blowing operation by pressing the sealing gas blowing button every 15 seconds, for example, unless there is an abnormality. The program is organized.

Therefore, the control unit 19 that performs the blowing operation when the start of supply of the seal gas is instructed starts the timer, and the next start of supply of the seal gas is not given until the predetermined time has been counted. In this case, control is performed so that the shutoff valve 16 of the seal gas supply path L2 is closed and the supply of the seal gas is stopped.

A typical value of the amount of seal gas blown in 15 seconds is 400 m ³ . This amount furnace front openable door type heat insulating board, the side wall of the converter horizontally, Rourakabe, 40 of the ceiling wall and the converter shield surrounded by the floor space volume 600 meters ³ - 1,000 m ³ near collection hood ~ 67 %. That is, it corresponds to a flow rate that can prevent leakage to the outside by filling only the inside of the converter shielding space with the sealing gas.

In addition, because the inside of the converter shielded space is an inert gas atmosphere, workers will not enter, but it is necessary to quickly operate the dust collector and exhaust the inert gas through the dust collection duct. There is.

Further, in the present embodiment, the seal gas blowing operation method has been individually described. However, an operation method in which the seal gas blowing operation methods are combined may be employed.

For example, when an alarm is issued when the wind direction changes, the ratio of the dust collection duct flow rate to the inert gas flow rate in the dust collection duct is obtained, and the gate valve 17 is kept until the obtained flow rate ratio can maintain the threshold value or more. The shut-off valve 16 may be controlled to close when the valve is adjusted in the closing direction and the threshold value or more cannot be maintained, or the seal gas blowing button is not pressed for more than 15 seconds even when the flow rate ratio is normal. it can.

According to this seal gas blowing operation method, the seal gas blowing operation in the seal gas blowing operation converter gas recovery can be performed most safely.

This application claims the benefit of priority based on Japanese Patent Application No. 2012-9319 filed on January 19, 2012 and Japanese Patent Application No. 2012-86798 filed on April 5, 2012 To do. The entire contents of the specifications of Japanese Patent Application No. 2012-9319 filed on January 19, 2012 and Japanese Patent Application No. 2012-86798 filed on April 5, 2012 are hereby incorporated by reference. Incorporated for.

The present invention can be used for a converter gas recovery facility for recovering a converter gas generated in a converter blowing process.

DESCRIPTION OF SYMBOLS 1 Converter 1a Furnace port 2 Collecting hood 3 Skirt part 4 Heat insulation board 4a Window part 5 Dust collection duct 6 Blowing duct 7, 8 Extension blowing duct 7a, 8a Blowing hole

Claims

In the converter gas recovery device that recovers the converter gas generated in the converter blowing process from the recovery hood,
An inert gas is mainly supplied to the converter space between the dust collection duct arranged on the front side of the furnace when viewed from the plane and the center of the converter furnace port, toward the air flow from the front side of the furnace to the converter furnace port. A converter gas recovery device comprising a blowing portion for sealing gas as a component.
The said gas is blown in from the said blowing part along the tilting axis of the said converter seeing from a plane, The blowing target of the said seal gas is orient | assigned to the furnace front side rather than the said converter furnace port. Converter gas recovery equipment.
The converter gas recovery device according to claim 1 or 2, wherein a pair of the blowing portions are arranged in a state of being symmetrically opposed with respect to the converter.
The converter gas recovery device according to claim 3, wherein the inlet of the blowing section is open to the left and right wall surfaces that house the converter.
4. The converter gas according to claim 3, wherein the blowing port of the blowing section opens from a left and right wall surface accommodating the converter to a tip of a duct extending along a tilting axis of the converter. Recovery device.
The converter gas recovery according to claim 1, wherein nitrogen gas produced as a by-product when oxygen used for blowing the converter is separated from air is used as the seal gas containing the inert gas as a main component. apparatus.
When recovering the converter gas from the recovery hood, in the seal gas blowing operation method of sealing the gap between the converter furnace port and the recovery hood with a seal gas,
Detect the change in the seal gas flow during converter gas recovery, or obtain the dust collection duct suction flow rate relative to the seal gas supply flow rate,
When the flow of the seal gas changes or when the dust collection duct suction flow rate with respect to the seal gas supply flow rate falls below a predetermined value, the supply amount of the seal gas is reduced or the supply of the seal gas is stopped. A sealing gas blowing operation method characterized by that.
The seal gas blowing operation method according to claim 7, wherein a change in the flow of the seal gas is detected by attaching a wind direction sensor to an internal observation window portion of a heat insulating plate installed on the front side of the converter.
The seal gas injection operation method according to claim 7, wherein a change in the flow of the seal gas is detected by attaching a wind direction sensor to a back side gap portion of a heat insulating plate installed on the front side of the converter.
The dust collection duct suction flow rate is obtained by converting the internal pressure of the dust collection duct into a flow rate, and when the ratio of the dust collection duct suction flow rate to the seal gas supply flow rate falls below a threshold value, the seal gas supply channel 8. The seal gas supply is stopped by adjusting the gate valve of the seal gas to reduce the seal gas supply amount until the threshold value or more can be maintained or by closing the shut-off valve of the seal gas supply path Seal gas blowing operation method.
When the start of the seal gas supply is commanded, the timer is started, and when the next seal gas supply start command is not given by the end of the predetermined time, the shut-off valve of the seal gas supply path is closed, The sealing gas blowing operation method according to any one of claims 7 to 10, wherein the supply of the sealing gas is stopped.