JP2002339011A - Facility and method for recovering exhaust gas from converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a facility for recovering the exhaust gas from a converter which can recover unburnt gas without lowering dust collecting efficiency even for a wide range of oxygen feeding speed in the converter and which can be reconstructed at a low cost even when the exhaust gas recovering facility is of a conventional type corresponding to a high oxygen feeding speed. SOLUTION: The above problem is solved with the converter exhaust gas recovering facility provided with: a dust collector 8 which is provided with a damper 9 having an adjustable opening degree and collects the dust of the gas generated from the converter 1 while adjusting the opening degree of the damper; an opening degree detector 23 for detecting the opening degree of the damper; induction blowers 13, 14 for sucking the gas exhausted from the dust collector; a revolving speed calculating means 24 for changing the revolving speed of the induction blowers on the basis of the signal detected with the opening degree detector; and a blower driving control unit 25 for controlling the revolving speed of the induced blowers on the basis of the output signal from the revolving speed calculating means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter exhaust gas recovery system and a recovery method.

[0002]

2. Description of the Related Art Gas generated at the time of decarburization of hot metal by oxygen blowing in a converter has a CO gas concentration at the converter furnace mouth of about 90%, a dust content of about 120 g / Nm ³ , and a temperature. About 150
It is in a state of 0 ° C., and its generation amount has reached 220,000 Nm ³ / hr in a large converter of 300 ton class.
This exhaust gas treatment method is roughly classified into two types: a complete combustion method in which CO gas in exhaust gas is completely burned with air and then cooled to remove dust, and a non-combustion method in which CO gas in the exhaust gas is cooled and removed without burning. Recently, the non-combustion method has been mainly adopted because of the relatively small size of the exhaust gas treatment equipment, the ease of maintenance, and the stable dust collection efficiency compared to the complete combustion method. Have been.

[0003] Most of the non-combustion type exhaust gas treatment equipment is a so-called "OG type exhaust gas recovery equipment". In this OG type exhaust gas recovery equipment (hereinafter simply referred to as "exhaust gas recovery equipment"), the rotation speed of the induction blower is fixed. The opening degree of the damper of the PA venturi installed as a secondary dust collector is adjusted so that the suction amount and the generated gas amount become substantially equal, and the converter furnace pressure is controlled within a predetermined range. However, conventional exhaust gas recovery equipment is designed so that exhaust gas can be treated even when the supply flow rate of oxygen into the converter (hereinafter referred to as “acid-feeding speed”) is maximum. In the case of low acid feed rates such as reslag blowing using hot metal and dephosphorization of hot metal, the amount of generated gas is small, and it is extremely difficult to recover unburned gas and increase recovery. .

[0004] This is because even when the damper of the PA venturi is in a fully closed state, the suction volume of the induced blower becomes larger than the generated gas volume at a low acid flow rate and a low exhaust gas flow rate. This is because the gas is mixed into the exhaust gas at the converter mouth, and the CO gas is burned by the atmosphere, so that the CO gas concentration becomes low and the CO gas cannot be recovered. Therefore, for example, the following problems occur.

At present, at the time of decarburization blowing of hot metal, manganese ore is added to the converter, and this manganese ore is reduced by carbon in the hot metal to reduce the amount of manganese added as ferroalloy. In this case, for example, manganese yield in the case of lowering the oxygen-flow-rate and if it is a constant of the blow until the end 50000Nm ³ / hr, the medium-term subsequent blowing from 50000Nm ³ / hr in Nm ³ / hr 25000 It is known that when the acid transfer rate is constant, the manganese yield decreases. This is because when the high acid feed rate is maintained until the end of blowing, the oxygen concentration in the molten steel increases, and the manganese yield decreases in inverse proportion to the oxygen concentration. Therefore, in order to improve the manganese yield, it is sufficient to lower the acid supply rate at the end of blowing, but the amount of gas generated decreases as the acid feeding rate decreases. And gas recovery becomes impossible. That is, the conventional exhaust gas recovery equipment has a problem that it is not possible to simultaneously increase the manganese yield and increase the gas recovery amount. If the exhaust gas with low CO gas concentration, that is, the exhaust gas with high oxygen concentration is recovered,
A serious accident such as an explosion will occur in the gas holder for recovery.

[0006] Further, in the dephosphorization treatment of hot metal using a converter, the acid supply rate is lower than that in the case of decarburization blowing, so that the amount of generated gas is small, and conventional exhaust gas recovery equipment is not available. The recovery of combustion CO gas is essentially unavoidable. By adding a carbon source such as coke or plastic into the converter to increase the concentration of CO gas in the exhaust gas and the flow rate of the exhaust gas, it is possible to recover unburned gas with conventional exhaust gas recovery equipment. It is difficult to stably increase the flow rate of exhaust gas by the supply of gas, and even if a carbon source is added, considering the fluctuation of gas generation, etc. There is a problem that recovery is not possible in practice.

To solve such a problem, Japanese Patent Application Laid-Open No. Sho 53-1110 has been proposed. In the same publication, the amount of gas generated in the furnace is predicted, and the PA
Perform independent control of the venturi damper or combination control of this damper and the damper of the induced blower,
The suction amount of the induction blower is approximated in advance to the amount of gas generated in the furnace,
Increases exhaust gas recovery rate.

[0008]

However, the method disclosed in JP-A-53-1110 has the following problems. That is, if the amount of gas generation increases rapidly due to abnormal combustion or the like during gas recovery under the condition of a small amount of gas generation, dust collection efficiency will deteriorate. This is a characteristic when the suction amount of the induction blower is controlled by the throttle control of the damper. Due to the characteristics of the device of the induction blower, as shown in FIG. This is because the pressure generated by the induction blower decreases on the side. FIG. 9 is a diagram showing a result of an investigation of a characteristic change when the damper of the induction blower is closed in the actual furnace. PA in FIG. 9 indicates a damper of a PA venturi,
D1 and D3 are dampers of the induction blower, and the numerical values indicate the damper opening.

Further, when estimating the amount of gas generated in the furnace, it is necessary to take into account the incremental amount accompanying the gasification of the auxiliary material added or charged into the furnace or the flue. It is difficult to predict the generated gas amount, the accuracy is extremely low, and it must be said that it is extremely difficult to stably increase the gas recovery efficiency.

As described above, an exhaust gas recovery system capable of stably recovering unburned gas corresponding to a wide range of gas generation has not yet been developed, and the development thereof has been eagerly desired. Was.

By the way, in the conventional exhaust gas recovery equipment, in order to increase the gas recovery amount or perform gas recovery in a region where the amount of generated gas is small, the exhaust gas recovery equipment is modified to a specification adapted to a low acid feed rate. Required, which requires a large amount of equipment cost. Exhaust gas recovery equipment corresponding to a wide range of gas generation rates has not been developed so far. It has to be installed.

The present invention has been made in view of such circumstances, and an object of the present invention is to cover a wide range of acid feed rates in a converter, such as from decarburization blowing of hot metal to dephosphorization. In addition, a converter exhaust gas recovery facility that can recover unburned gas without lowering the dust collection efficiency and that can be remodeled at a low facility remodeling cost even with a conventional exhaust gas recovery facility that supports a high acid feed rate. To provide.

[0013]

SUMMARY OF THE INVENTION A converter exhaust gas recovery system according to a first aspect of the present invention includes a damper whose opening can be adjusted, and a dust collector that removes gas generated from the converter while adjusting the opening of the damper. An opening detector for detecting an opening of the damper, an induction blower for sucking gas discharged from the dust collector, and changing a rotation speed of the induction blower based on a detection signal from the opening detector. The converter exhaust gas recovery equipment according to the second invention is characterized by comprising: a rotation speed calculating means; and a blower drive control device for controlling the rotation speed of the induction blower based on an output signal from the rotation speed calculating means. In the first invention, the rotation speed calculating means generates an output signal for changing the rotation speed of the induction blower when the damper provided in the dust collector reaches an opening degree at which the control becomes impossible. In the converter exhaust gas recovery equipment according to the third invention, in the first invention or the second invention, the dust collection capacity of the dust collector is further calculated based on the rotation speed of the induction blower, and the dust collection capacity is set to a reference value. In the following case, there is provided a dust collecting capability calculating means for limiting the lower limit of the rotation speed of the induction blower.

Further, in the converter exhaust gas recovery method according to the fourth invention, while controlling the opening degree of a damper provided in the dust collector to control the converter furnace pressure within a predetermined range, the induction blower blows the converter exhaust gas from the converter. In the converter exhaust gas recovery method of sucking and recovering exhaust gas, when the damper reaches an opening at which the furnace port pressure becomes uncontrollable, the damper opening is set within a controllable range of the furnace port pressure. The converter exhaust gas recovery method according to the fifth invention is characterized in that the rotation speed of the induction blower is changed so that the damper reaches an opening at which the control of the furnace port pressure becomes impossible. In this case, the ratio is multiplied by a ratio with respect to the rated rotation speed of the induction blower to determine the rotation speed of the induction blower. Is the opening at which the furnace pressure becomes uncontrollable The rotation speed of the induction blower is determined so that the degree of opening of the damper reaches a predetermined value when the damper reaches the predetermined value. In any one of the sixth inventions, the dust collecting capability of the dust collector is obtained based on the newly determined rotation speed of the induction blower, and when the dust collection capability is equal to or less than the reference value, the lower limit of the rotation speed of the induction blower is determined. The converter exhaust gas recovery method according to the eighth invention is characterized in that the
In any one of the inventions to the seventh invention, in the converter,
The present invention is characterized in that a synthetic resin is introduced as an auxiliary material into a furnace or an exhaust gas channel to refine hot metal, and a gas generated by the refining is recovered.

In the present invention, a damper of a PA venturi installed as a dust collector (hereinafter referred to as "PA damper")
Reaches the opening where the converter pressure cannot be controlled.
The suction rate of the induction blower is adjusted by changing the rotation speed of the induction blower so that the opening degree of the A damper is within the controllable range of the furnace port pressure. Even in the low acid feed rate range such as at the end of decarburization blowing and dephosphorization, the incorporation of air into the converter exhaust gas is prevented, and CO gas etc. generated from the converter is unburned. It is possible to recover as it is. In addition, even in the case of a conventional exhaust gas recovery facility corresponding to a high acid feed rate, the above-described problem can be achieved by a relatively simple facility modification in which the rotation speed of the induction blower is changed according to the degree of opening of the PA damper. It is possible, and equipment remodeling costs can be significantly reduced. Furthermore,
The dust collecting capacity calculating means calculates the dust collecting capacity of the dust collector based on the rotation speed of the induction blower, and when the dust collection capacity becomes equal to or less than the reference value, the lower limit of the rotation number of the induction blower is limited. There is no reduction in efficiency.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view showing an embodiment of the present invention, and is a schematic configuration diagram of a converter exhaust gas recovery facility according to the present invention.

As shown in FIG. 1, an upper blowing lance 3 is inserted from above into a converter 1 containing hot metal 2, and oxygen is blown from the upper blowing lance 3 onto the hot metal 2 to form a hot metal 2. Decarburization blowing and dephosphorization of the hot metal 2 are performed. Hot metal 2
Due to the decarburization blowing and dephosphorization treatment, exhaust gas mainly composed of CO gas is generated from the furnace.

A flue 4 is installed above the converter 1. In the latter part of the flue 4, a primary dust collector 6, an elbow separator 7, a secondary dust collector 8, an elbow separator 10, an exhaust gas flow meter 11, a suction fan damper 12. Induction blower 1
3. The induction blower 14, the silencer 15, and the three-way valve 16 are installed in this order, and constitute an exhaust gas recovery flow path. The exhaust gas flow path after the three-way valve 16 is branched into two, one is a flow path that is radiated from the chimney 18 to the atmosphere,
The other one reaches the gas holder 19 via the recovery valve 17,
The flow path is collected in the gas holder 19. The induction blower 13 is driven by an electric motor 26 and the induction blower 1
4 is driven by an electric motor 27, whereby the generated gas in the converter 1 is sucked and diffused from the chimney 18 or collected in the gas holder 19. FIG. 1 shows an example in which two induction blowers 13 and 14 are installed in series. However, the number of induction blowers is not limited to two, and may be three or more or one.

The side of the flue 4 that is connected to the furnace opening of the converter 1 is called a skirt 5 and has a structure that can be moved up and down. In principle, the furnace port is in close contact with the furnace port. A furnace pressure detector 2 for measuring the converter furnace pressure is provided on the skirt 5.
0 is set, and the measurement result of the furnace pressure detector 20 is input to the furnace pressure control computer 21.

A PA damper 9 is installed in the PA venturi installed as the secondary dust collector 8, and the opening of the PA damper 9 is adjusted by a PA damper driving device 22. A signal from the furnace pressure control computer 21 is input to the PA damper drive device 22, and the PA damper drive device 22 adjusts the opening of the PA damper 9 based on a signal from the furnace pressure control computer 21. .

That is, based on the measurement result of the furnace port pressure detector 20, the furnace pressure control computer 21 changes the furnace port pressure to a predetermined value, for example,-
As a 5mmH ₂ O~ + 5mmH ₂ O range, P
The opening of the A damper 9 is adjusted. The control method of the furnace port pressure may be any control method as long as the controllability is high. Here, the method of high controllability means that, as shown in FIG. 2, when the setting of the furnace port pressure is changed, the period during which the setting value approaches the set value (called “transient characteristic”) is early, This is a control method in which the deviation (hereinafter referred to as “steady characteristic”) is small, the transient characteristic is 6.0 seconds or less, and the steady characteristic is ± 4.0 mmH ₂ O or less.
Specifically, general PI control is sufficiently possible. FIG. 2 is a diagram showing an example of a furnace port pressure change when the set value of the furnace port pressure is changed.

When the opening of the PA damper 9 is fully closed when the furnace pressure is controlled in this manner, the amount of generated gas is small, and It can be understood that entrainment has occurred and gas combustion (referred to as “secondary combustion”) has occurred. On the other hand, when the degree of opening of the PA damper 9 has been fully opened, the amount of generated gas is large. Thus, it can be understood that the generated gas is spouting from the furnace opening of the converter 1. Thus, without estimating the gas generated in the furnace, P
The behavior of the gas generated in the furnace can be grasped from the opening of the A damper 9.

The secondary dust collector 8 is provided with an opening detector 23 for detecting the opening of the PA damper 9, and the value detected by the opening detector 23 is transmitted to a rotation speed calculator 24. . The rotation speed calculator 24 determines whether or not to change the rotation speed of the induction blowers 13 and 14 based on the value detected by the opening detector 23, and outputs the determination result to the blower drive control device 25. The blower drive control device 25 controls the rotation speeds of the electric motors 26 and 27, that is, the rotation speeds of the induction blowers 13 and 14, to a predetermined value based on this signal.

Hereinafter, from the opening degree of the PA damper 9,
Rotational speed calculator 24 to recover more gas
Will be described with reference to FIG. FIG. 3 is a diagram showing a first processing flow in the rotation speed calculator 24.

First, the PA damper opening value (X) transmitted from the opening detector 23 and a preset PA
Comparison with the reference value (A) of the fully closed area of the damper 9 is performed (step 1). The frequency of step 1 may be performed at an arbitrary interval ranging from several seconds to several minutes. Here, the fully-closed area reference value (A) is not the mechanically fully-closed area of the equipment, but PA
Even if the opening of the damper 9 is smaller than that, the PA damper 9
Is a region in which the amount of air passing therethrough does not substantially change or hardly changes, and varies depending on the equipment specifications of the PA damper 9, for example, a region in which the opening degree is about 7% or less.

If the PA damper opening value (X) is within the fully closed region, the induction blowers 13, 1 are obtained based on the following equation (1).
Then, the number of rotations is calculated (step 2).

[0027]

(Equation 1)

Then, the induction blower 1 at the new rotation speed
Calculate the generated pressures (also referred to as suction pressures) of Steps 3 and 14 (Step 3). This calculation is performed based on the induced blower performance curve at the rated speed shown in FIG. 4 (1000 rpm corresponds to the rated speed in FIG. 4). That is, the air volume (Q) at the new rotation speed can be obtained by the following equation (2), and the generated pressure (P) at the new rotation speed can be obtained by the following equation (3). It is possible to obtain an induced blower performance curve for each rotation speed as shown in FIG. Here, as shown in FIG. 5, the pressure at the point where the air volume is the same on the induction fan performance curve for each rotation speed is the generated pressure (P) at the new rotation speed. In addition, FIG.
FIG. 4 is a diagram showing together a performance curve of the damper 9 and an operation state of the PA damper 9 based on a first calculation method.

[0029]

(Equation 2)

[0030]

(Equation 3)

Next, the dust content (D) in the exhaust gas at the new rotational speed is estimated (step 4). The dust content (D) can be determined from a dust curve determined at the time of designing exhaust gas recovery equipment. FIG. 6 shows an example of the dust containing curve. This is a curve representing the dust collecting ability from the state of the differential pressure in the primary dust collector 6 and the secondary dust collector 8. Differential pressure of primary dust collector 6 and secondary dust collector 8
Since the differential pressure obtained by adding the differential pressure is caused by the pressure (P) generated by the induction blowers 13, 14, the induction blowers 13, 14 are used.
The dust content (D) in the exhaust gas can be determined from the generation pressure (P) of the gas. That is, in FIG. 6, the dust content (D) can be obtained from the dust curve at the point where the horizontal axis is equal to the generated pressure (P). The dust collector pressure loss on the horizontal axis in FIG. 6 is a differential pressure obtained by adding the differential pressure of the primary dust collector 6 and the differential pressure of the secondary dust collector 8.

The expected value of the dust content (D) obtained by the above calculation and a preset environmental reference value (5 in this embodiment)
0 mg / Nm ³ ) (Step 5), and when the predicted value of the dust content (D) is smaller than the environmental standard value, the rotation speeds of the induction blowers 13 and 14 are set to the new rotation speeds. , A signal is sent from the rotation speed calculator 24 to the blower drive controller 25. When the predicted value of the dust content (D) is larger than the environmental reference value, a signal is sent from the rotation speed calculator 24 to the blower drive control device 25 so that the rotation speed of the induction blowers 13 and 14 is maintained at the current level. Sent. In this case, the PA damper 9 remains in the fully closed state, and the concentration of unburned gas in the exhaust gas decreases due to the entrainment of air at the furnace opening of the converter 1, so that the gas recovery in the gas holder 19 is not performed. The fuel is completely burned and released from the chimney 18 to the atmosphere. Usually, when the concentration of unburned gas in the exhaust gas becomes about 50% or less, the gas recovery is abandoned and the atmospheric emission is performed.

On the other hand, if the PA damper opening value (X) is larger than the fully closed area reference value (A) in step 1, the preset fully open area reference value (B) and the PA damper opening value are set in advance. (X) (step 6). Here, the fully open area reference value (B) is not the mechanically fully open area of the equipment, but the open degree of the PA damper 9 is larger than that.
This is a region where the air volume passing through the PA damper 9 does not substantially change or hardly changes, and varies depending on the equipment specifications of the PA damper 9, for example, a region where the opening degree is about 30% or more.

When the PA damper opening value (X) is smaller than the full open area reference value (B), the opening of the PA damper 9 is within an appropriate range. Is sent from the rotation speed calculator 24 to the blower drive control device 25 so as to maintain If the PA damper opening value (X) is larger than the full open area reference value (B), the rotational speeds of the induction blowers 13 and 14 are calculated based on the following equation (4) (step 7).

[0035]

(Equation 4)

Then, the preset blower 1
The rotation speed upper limit value (UL) of 3, 14 is compared with the new rotation speed (step 8). If the new rotation speed is larger than the rotation speed upper limit value (UL), the current rotation speed is maintained, and If the new rotation speed is equal to or less than the rotation speed upper limit value (UL), the rotation speed calculator 24 sends the blower drive control device 2 so that the new rotation speed becomes the new rotation speed.
A signal is sent to 5.

The operating state of the PA damper 9 according to the first calculation method described above is as follows. That is, as shown in FIG. 4, the rotation speed of the induction blowers 13 and 14 is 1000 r.
When the amount of gas generation decreases when exhaust gas is collected in the state of pm, the opening degree of the PA damper 9 gradually decreases while the rotation speeds of the induction blowers 13 and 14 remain unchanged, and the PA The opening of the damper 9 reaches the reference value (A) for the fully closed area. The degree of opening of the PA damper 9 is the reference value of the fully closed area (A)
, The rotation speed of the induction blowers 13 and 14 is 9
00 rpm, and the degree of opening of the PA damper 9 is out of the fully closed region. In this case, the suction gas flow rate is reduced by the induction blower 13,
The opening degree of the PA damper 9 is determined so that it does not change before and after the change of the rotation speed 14. The amount of generated gas further decreases,
Even if the rotation speed of the induction blowers 13 and 14 is 900 rpm, when the opening degree of the PA damper 9 reaches the reference value (A) of the fully closed area, the rotation speeds of the induction blowers 13 and 14 are 800 rpm.
To decline. Although not shown in FIG. 4, as long as the predicted value of the dust content (D) satisfies the environmental standard value, the induction blower 13,
The number of rotations of 14 may be reduced to 700 rpm or even 600 rpm.

On the other hand, when the rotation speed of the induction blowers 13 and 14 is 8
If the amount of generated gas increases while the gas is collected at a speed of 00 rpm, the opening degree of the PA damper 9 gradually increases while the rotation speeds of the induction blowers 13 and 14 remain unchanged, and the full open area reference value (B) is reached. When the opening degree of the PA damper 9 reaches the fully open area reference value (B), the rotation speed of the induction blowers 13 and 14 increases to 900 rpm, and the opening degree of the PA damper 9 is out of the fully open area. In this case, the opening degree of the PA damper 9 is determined so that the suction gas flow rate does not change before and after the rotation speed of the induction blowers 13 and 14 is changed. The amount of gas generated further increases, and the induced blower 1
When the opening degree of the PA damper 9 reaches the full open area reference value (B) even if the rotation speed of the PAs 3 and 14 is 900 rpm, the rotational speeds of the induction blowers 13 and 14 increase to 1000 rpm. In this case, the induction blowers 13, 14 are 1000r
It is designed so that the maximum acid feed rate can be handled at a rotation speed of pm, and no higher rotation speed is required. still,
In the equations (1) and (4), the number of revolutions is changed every 10%, but this ratio is not limited to 10% and can be an arbitrary value.

Next, a second calculation method of the rotation speed calculator 24 for recovering a larger amount of gas will be described with reference to FIGS. This calculation method is based on the induction blower 13, 1
When changing the rotation speed of 4, the opening of the PA damper 9
This is a method in which the rotation speeds of the induction blowers 13 and 14 are changed so that the flow rate of the exhaust gas passing through the PA damper 9 becomes the opening range in which the exhaust gas flow is most easily controlled. FIG. 7 shows the rotational speed calculator 24.
FIG. 8 is a diagram showing a performance curve of the PA damper 9 and an operation state of the PA damper 9 based on the second calculation method.

As shown in FIG. 7, the comparison between the PA damper opening value (X) transmitted from the opening detector 23 and the preset reference value (A) of the fully closed area of the PA damper 9 is performed. Perform (step 11). The frequency of step 11 may be performed at an arbitrary interval ranging from several seconds to several minutes. If the PA damper opening value (X) is within the fully closed region, the rotation speeds of the induction blowers 13 and 14 are calculated by the following method (step 12).

That is, the exhaust gas flow rate at the time when the opening degree of the PA damper 9 reaches the reference value (A) for the fully closed region is measured by the exhaust gas
1 or the PA damper performance curve shown in FIG. Then, based on the previously obtained PA damper performance curve for each rotational speed, the exhaust gas flow rate at the time when the opening of the PA damper 9 reaches the fully closed region reference value (A) can be passed at the specified opening. Find the number of revolutions. Here, the specified opening is an opening at which the PA damper performance can be most linearized and the exhaust gas flow rate is most easily controlled, and the normal PA damper 9 has an opening of about 20%. A certain range may be set as the specified opening degree. Since the suction air volume of the induction blowers 13 and 14 at each rotation speed can be obtained by the above-described equation (2), the performance curve of the PA damper 9 at each rotation speed can be obtained.

Next, the pressure generated by the induced blowers 13 and 14 at the obtained new rotation speed is calculated (step 13).
The dust content (D) in the exhaust gas at the new rotational speed is estimated (step 14), and the predicted value of the dust content (D) is compared with a preset environmental reference value (step 15). If the predicted value of the dust content (D) is larger than the environmental standard value, the current rotational speed is maintained, and if the predicted value of the dust content (D) is smaller than the environmental standard value, induction is performed. Blower 13,1
So that the rotation speed of the rotation speed calculator 4 becomes the new rotation speed.
Sends a signal to the blower drive control device 25. Steps 13 to 15 are exactly the same as steps 3 to 5 of the above-described first calculation method, and a description thereof will be omitted.

On the other hand, if the PA damper opening value (X) is larger than the fully closed area reference value (A) in step 1, the preset fully open area reference value (B) and the PA damper opening value are set. (X) (step 16). P
When the A damper opening value (X) is smaller than the full open area reference value (B), the opening of the PA damper 9 is within an appropriate range, and the rotation speeds of the induction blowers 13 and 14 maintain the current state. Thus, the signal is sent from the rotation speed calculator 24 to the blower drive control device 25.

If the PA damper opening value (X) is larger than the fully open area reference value (B), the above-described step 12 is executed.
The rotational speeds of the induction blowers 13 and 14 are calculated by the same method as that described above (step 17). Then, the preset upper limit rotation speeds (UL) of the induction blowers 13 and 14 are compared with the new rotation speed (step 18). If the new rotation speed is larger than the rotation speed upper limit (UL), the current rotation speed is determined. A signal is sent from the rotation speed calculator 24 to the blower drive control device 25 so as to maintain the rotation speed, and if the new rotation speed is equal to or lower than the rotation speed upper limit (UL), the rotation speed becomes the new rotation speed.

The operating state of the PA damper 9 according to the above-described second calculation method is as follows. That is, as shown in FIG. 8, the rotation speed of the induction blowers 13 and 14 is 1000 r.
When the amount of gas generation decreases when exhaust gas is collected in the state of pm, the opening degree of the PA damper 9 gradually decreases while the rotation speeds of the induction blowers 13 and 14 remain unchanged, and the PA The opening of the damper 9 reaches the reference value (A) for the fully closed area. The degree of opening of the PA damper 9 is the reference value of the fully closed area (A)
Is reached, the exhaust gas flow at this point (about 9000)
0Nm ³ / hr) and set as the specified opening 20
The number of revolutions at which the exhaust gas flow rate of about 90000 Nm ³ / hr is passed at an opening of% is determined. In FIG. 8, the case of 800 rpm corresponds to this. Therefore, the generated gas is recovered by reducing the rotation speed of the induction blowers 13 and 14 to 800 rpm. If the opening degree of the PA damper 9 reaches the fully closed region reference value (A) even when the amount of generated gas is further reduced and the rotation speed of the induction blowers 13 and 14 is 800 rpm, the rotation speed is obtained in the same manner. The rotation speed of the induction blowers 13 and 14 is further reduced.

On the other hand, when the rotation speed of the induction blowers 13 and 14 is 8
When the gas generation amount increases while the gas is being recovered at 00 rpm, the opening degree of the PA damper 9 gradually increases while the rotation speeds of the induction blowers 13 and 14 remain unchanged,
And the opening degree of the PA damper 9 is the fully open area reference value (B).
To reach. If the degree of opening of the PA damper 9 reaches the reference value (B) in the fully open area, the exhaust gas flow rate at this point (about 1
15,000 Nm ³ / hr) is determined, and the rotation speed at which the exhaust gas flow rate of about 115000 Nm ³ / hr is passed at an opening of 20% is determined. In FIG. 8, the case of 920 rpm corresponds to this. Therefore, the rotation speed of the induction blowers 13 and 14 is set to 9
The generated gas is recovered at an increased speed of 20 rpm.

The two types of calculation methods of the rotation speed calculator 24 have been described above.
It is not limited to the type, and various changes are possible. In short, the induction blower 1 is set so that the opening degree of the PA damper 9 is in a range in which the amount of air passing through the PA damper 9 can be controlled.
The rotational speeds of the dampers 3 and 14 may be changed. Therefore, when the opening of the PA damper 9 is going to be in the fully closed region, the rotational speed is reduced, and conversely, the opening of the PA damper 9 is in the fully open region. If so, the number of rotations may be increased.

Next, a method for recovering the gas generated from the converter 1 by using the converter exhaust gas recovery equipment according to the present invention thus configured will be described.

First, hot metal 2 is charged into a converter 1 as a main raw material, and if necessary, quicklime as a flux,
A manganese ore in place of Fe-Mn alloy iron, iron ore and a mill scale as a dephosphorizing agent, and coke and a synthetic resin as a carbon source are added as auxiliary raw materials.
, Pure oxygen is blown toward the hot metal surface to perform decarburization blowing and dephosphorization of the hot metal 2. Although not shown in FIG. 1, a stirring gas may be blown into the hot metal 2 from the furnace bottom of the converter 1, or pure oxygen may be blown from the furnace bottom of the converter 1 in place of the upper blowing lance 3.

In particular, since the synthetic resin has a lower sulfur and phosphorus content than carbon sources such as coke and graphite, it is possible to heat the hot metal 2 without contaminating the hot metal 2 by the heat of combustion. It is possible to increase the mixing ratio of scrap and manganese ore. In addition, CO gas is generated by the combustion of the synthetic resin, and the CO ₂ gas is reformed into CO gas by the carbon in the synthetic resin. Therefore, the concentration of the unburned gas in the exhaust gas and the flow rate of the exhaust gas increase. It is possible to increase the recovery amount of the combustion gas. Further, most of the synthetic resin waste is conventionally dumped in a garbage landfill or the like, but is supplied to the converter 1 for effective recycling. Therefore, in both the decarburization blowing and dephosphorization of the hot metal 2, it is preferable to add and add synthetic resin, preferably synthetic resin waste, into the converter 1 or the flue 4 during the refining.

In the case of decarburization blowing, oxygen is blown at an optimum acid supply rate according to the carbon concentration in the hot metal 2. In the case of dephosphorization, the optimum acid transfer rate for the dephosphorization treatment is used. Refining by blowing oxygen. The gas generated by the refining is sucked by the induction blowers 13 and 14. In this case, as described above, the furnace opening pressure is controlled to a predetermined range by adjusting the opening degree of the PA damper 9 by the furnace pressure control computer 21, and the opening degree of the PA damper 9 is set to a fully closed area or a fully open area. When it reaches, the induction blower 1
The rotation speeds of the dampers 3 and 14 are changed, and the opening degree of the PA damper 9 is returned to a range where the flow rate can be controlled. As a result, converter 1
Since the flow rate of the gas generated from the air and the suction flow rate by the induction blowers 13 and 14 are controlled to be substantially equal, the entrainment of the atmosphere at the furnace port of the converter 1 is suppressed even in the low acid feed rate range, and the unburned The amount of gas recovery can be increased.

When the gas generated from the converter 1 is recovered using the converter exhaust gas recovery equipment of the present invention, it is possible to increase the gas recovery by 2 Nm ³ per ton of hot metal by increasing the gas recovery at the end of blowing when decarburizing and blowing. In addition, at the time of the dephosphorization treatment where gas recovery was conventionally impossible, gas recovery of 50 Nm ³ per ton of hot metal was possible. Further, in this case, the dust content in the exhaust gas did not increase at all, and no air pollution or dust obstacle in the gas recovery equipment occurred.

[0053]

According to the present invention, the amount of suction by the induction blower is adjusted by changing the rotation speed of the induction blower so that the opening degree of the damper is within the controllable range of the furnace port pressure. The amount of gas generated from the furnace and the amount of suction from the induction blower are almost the same, and even at the end of decarburization blowing and in the low acid feed rate region such as the dephosphorization process, air is not mixed into the converter exhaust gas. Thus, the CO gas and the like generated from the converter can be recovered without being burned, and an industrially advantageous effect is brought about.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a schematic configuration diagram of a converter exhaust gas recovery facility according to the present invention.

FIG. 2 is a diagram showing an example of a furnace port pressure change when a set value of a furnace port pressure is changed.

FIG. 3 is a diagram showing a first processing flow in the rotation speed calculator shown in FIG. 1;

FIG. 4 shows a performance curve of a PA damper and a PA according to the present invention.
It is a figure which also shows the operation state of a damper.

FIG. 5 is a diagram illustrating an example of an induced blower performance curve for each rotation speed.

FIG. 6 is a diagram showing an example of a dust curve.

FIG. 7 is a view showing a second processing flow in the rotation speed calculator shown in FIG. 1;

FIG. 8 shows a performance curve of a PA damper and a PA according to the present invention.
It is a figure which also shows the operation state of a damper.

FIG. 9 is a diagram showing a result of investigating a characteristic change of an induced blower according to a conventional technique in which a damper of an induced blower is closed to control a suction amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Converter 2 Hot metal 3 Top blowing lance 4 Flue 6 Primary dust collector 8 Secondary dust collector 9 PA damper 13 Induction blower 14 Induction blower 16 Three-way valve 18 Chimney 19 Gas holder 20 Furnace pressure detector 21 Furnace pressure control calculator 22 PA Damper drive device 23 Opening degree detector 24 Revolution speed calculator 25 Blower drive control device 26 Motor 27 Motor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Miyahara 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tomoo Izawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun F-term in Honko Co., Ltd. (reference) 4K070 AB12 AB18 AB20 CA01 CA05 CA11 DA05 DA09 EA30

Claims (8)

[Claims] 1. A dust collector, comprising: a damper capable of adjusting an opening degree; removing a gas generated from a converter while adjusting the opening degree of the damper; an opening degree detector for detecting an opening degree of the damper; An induction blower that sucks gas discharged from the dust collector, and a rotation speed calculation unit that changes the rotation speed of the induction blower based on a detection signal from the opening degree detector,
A blower drive control device for controlling the number of rotations of the induction blower based on an output signal from the number of rotations calculation means, the converter exhaust gas recovery equipment. 2. The method according to claim 1, wherein the rotation speed calculating means issues an output signal for changing the rotation speed of the induction blower when the damper provided in the dust collector reaches an opening at which the dust collector becomes uncontrollable. The converter exhaust gas recovery facility according to claim 1. 3. The dust collecting capacity of the dust collector is calculated based on the number of revolutions of the induction blower, and the lower limit of the number of revolutions of the induction blower is limited when the dust collecting capacity is less than a reference value. The converter exhaust gas recovery equipment according to claim 1 or 2, further comprising a calculating means. 4. A converter for sucking and recovering gas discharged from a converter by an induction blower while controlling the opening of a damper installed in a dust collector to control a converter furnace pressure within a predetermined range. In the exhaust gas recovery method, when the damper reaches an opening at which the furnace port pressure cannot be controlled, the rotational speed of the induction blower is changed so that the damper opening is within a controllable range of the furnace port pressure. A method for collecting exhaust gas from a converter. 5. When the damper reaches an opening at which the furnace port pressure cannot be controlled, a ratio is multiplied by a ratio to a rated rotation speed of the induction blower to determine a rotation speed of the induction blower. The converter exhaust gas recovery method according to claim 4. 6. The rotation speed of the induction blower is determined so that when the damper reaches an opening at which the furnace port pressure cannot be controlled, the opening of the damper has a predetermined value. The converter exhaust gas recovery method according to claim 4, wherein 7. A dust collecting capability of the dust collector is obtained based on a newly determined rotation speed of the induction blower, and when the dust collection capability becomes equal to or less than a reference value, a lower limit of the rotation speed of the induction blower is limited. The converter exhaust gas recovery method according to any one of claims 4 to 6, characterized in that: 8. The converter according to claim 4, wherein a synthetic resin is charged as an auxiliary material into the furnace or the exhaust gas channel to refine the hot metal and recover a gas generated by the refinement. Item 8. The converter exhaust gas recovery method according to any one of Items 7 to 13.