JP2002267373A - Solid-gas separating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a solid-gas separating device to efficiently collect dust on the upstream side of the induction exhauster of a ventilating and dust collecting facility even when the dust has small particle diameters or is scattered in a gas flow. SOLUTION: The solid-gas separating device is constituted in such a way that a dust separating branch duct is provided on the upstream side of the inlet duct of the induction exhauster of the ventilating and dust collecting facility and connected to a gas duct provided on the upstream side of the branching section of the branch duct so that the duct may linearly communicate with the gas duct. Then the inlet duct of the exhauster is connected in an upwardly inclined state to the upper surface of the gas duct on the upstream side of the branch duct and the dust contained in an exhaust gas is separated from the exhaust gas in the branching section by utilizing the interaction between the difference between the inertial forces of the gas and dust and the fluid force caused by the deflection of the flowing direction of the gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-gas separation device installed upstream of an induced exhaust fan in a ventilation and dust collection system of a metal smelting plant.

[0002]

2. Description of the Related Art In a metal smelting factory such as a steelmaking factory or an electric furnace factory, a large amount of dust-containing gas is generated during charging, melting, tapping and discharging of slag, thereby deteriorating the working environment in the building. Ventilation hoods are installed around the furnace, at the top of the building, and at other places where dust is generated.The dust-containing gas is sucked by the induced exhaust fan, and the dust collector such as a bag filter is installed downstream of the induced exhaust fan. After dust removal, it is released into the atmosphere.

[0003] Fig. 7 shows a conventional example of a ventilation dust collecting facility in a steelmaking plant. 1 is a converter in a building, 2 is a skirt for closing a furnace opening of the converter 1, and a hood of a converter exhaust gas treatment facility. 3 is provided at the lower end so as to be able to move up and down. A ventilation hood 4 in front of the furnace of the ventilation dust collecting facility is provided around the skirt 2, and a gas duct 5 is connected to the ventilation hood 4 in front of the furnace. The gas duct 5 is guided from the building interior to the building exterior, and an induction blower 6 and a bag filter 7 are installed in order on the way and connected to the emission chimney 8.

[0004] The ventilation and dust-collecting equipment of the steelmaking plant configured as described above drives the induction blower 6 when charging hot metal into the converter 1, melting the steel, and discharging the molten steel and slag, and operates the converter. The dust-containing gas in the vicinity of the furnace port 1 is sucked from the ventilating hood 4 in front of the furnace as shown by an arrow, and guided to the bag filter 7 downstream of the induction blower 6 through the ventilating duct 5 in front of the furnace to collect dust and then diffuse after dust collection. Gas is emitted from the chimney 8 into the atmosphere.

[0005] By the way, dust contained in gas generated at the time of charging hot metal, melting, tapping and discharging of slag is carbon-based,
Since a large amount of iron-based hard large-particle dust is contained, in the ventilation dust collection equipment in which the bag filter 7 is installed downstream of the induction exhaust fan 6, the casing of the induction exhaust fan 6 and the impeller are severely worn, and the There is a problem that the filter cloth of the filter 7 is severely worn.

To solve such a problem, Japanese Patent Laid-Open No.
A duct structure of a dust collector disclosed in JP-A-109377 is proposed. As shown in FIG. 8, the duct structure of this dust collecting device is a dust collecting device in which a dust collecting hood and a bag filter communicate with each other through a duct through a blower. Shield 31
And a dust chute 32 is provided on the lower surface of the duct immediately before the shield installation position. According to the duct structure of the dust collector, dust having a large particle diameter and a high bulk specific gravity flowing under the duct 30 can be efficiently collected.

[0007] However, the above duct structure has a drawback that when the particle diameter of the dust is small, the trapping effect cannot be expected, and the dust scattered along with the gas flow cannot be collected.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, the present invention is effective in reducing dust having a small particle diameter and dust scattered on a gas flow upstream of an induced exhaust fan of a ventilation dust collector. An object of the present invention is to provide a solid-gas separation device that can collect well.

[0009]

A solid-gas separation device according to the present invention for solving the above-mentioned problems is provided with a branch duct for dust separation provided upstream of an inlet duct of an induced exhaust fan of a ventilation dust collecting facility. The duct is connected so as to communicate with the gas duct upstream of the branch part in a straight line, and the inlet duct of the induced exhaust fan is connected to the upper part of the upstream gas duct at the branch part of the branch duct by inclining upward, and is connected to the branch part. Thus, the exhaust gas and the dust in the exhaust gas are separated by the interaction of the fluid force due to the difference between the inertial forces of the two and the turning of the flow direction.

In the above solid-gas separation device of the present invention, the upward inclination angle θ of the inlet duct of the induced exhaust fan with respect to the branch duct for dust separation is preferably about 20 ° to 30 °. Also, the horizontal distance L of the branch duct for dust separation
Is preferably about 5 times the height in the branch duct. Further, it is preferable that the end of the branch duct for separating dust is guided into a water tank and sealed, and the water tank is provided with a slurry stirring / discharging device and a seal water replenishing device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the solid-gas separation device of the present invention will be described with reference to FIG. Reference numeral 1 denotes a converter inside a building, and 2 denotes a skirt for closing a furnace opening of the converter 1, which is provided at a lower end of a hood 3 of a converter exhaust gas treatment facility so as to be able to move up and down. A ventilation hood 4 in front of the furnace of the ventilation dust collecting facility is provided around the skirt 2, and a gas duct 5 is connected to the ventilation hood 4 in front of the furnace. The gas duct 5 is guided from the building interior to the building exterior, and an induction exhaust fan 6 and a bag filter 7 are installed in order on the way and connected to the emission chimney 8. A branch duct 10 for dust separation is provided upstream of the inlet duct 9 of the induced exhaust fan 6 in the ventilation and dust collection equipment of the steelmaking plant having such a configuration, and the branch duct 10 is aligned with the gas duct 5 upstream of the branch portion S. Are connected so as to communicate with each other, and the inlet duct 9 of the induced exhaust fan 6
Is connected to the upper surface of the upstream gas duct 5 in an inclined manner at the branch portion S of the branch duct 10, and the exhaust gas and the dust in the exhaust gas are separated at the branch portion S by the difference in inertial force between the two and the flow direction. The separation is performed by the interaction of the fluid force due to the deflection.

The basic principle of the solid-gas separation device of the present invention in the above-mentioned ventilation dust collecting facility will be described. The mass of the dust particles is M, the mass of the exhaust gas molecules is m, the exhaust gas speed immediately before the branch point is v1, the exhaust gas speed immediately after the branch point is v1 ', the dust particle velocity immediately before the branch point is v2, and the dust velocity immediately after the branch point is v.
2 ′, the angle formed by the impulse given by the induced exhaust fan with the traveling direction of the exhaust gas is θ1 (<π / 2), and the angle formed by the impulse given by the induced exhaust fan with the traveling direction of the acquisition of the dust particles is θ2 ( <Π / 2). Note that v2 = v1 × 0.
It is about 6 to 0.4, but here, v2 = v1.
Although the impulse generated by the induced exhaust changes the speed of the exhaust gas and the dust particles, there is no significant change in the speed immediately before the branch point and immediately after the branch point at a position close to the branch point. Therefore, -v1- =
−v1 ′ − = − v2 − = − v2′−. Here, the mass of the dust contained in the exhaust gas is clearly m << M. In addition, the speed of both exhaust gas and dust particles is not changed by impulse by the induced exhaust fan. In such a situation, if the exhaust gas obtains an impulse F by an induced exhaust fan and thereby obtains an angle of θ1 with respect to the current traveling direction, FIG.

[0013]

(Equation 1)

Similarly, assuming that dust particles obtain an equivalent impulse F by an induced exhaust fan, FIG.

[0015]

(Equation 2)

As described above, dust particles are compared with exhaust gas.
The degree to which the traveling direction can be bent by the induced exhaust fan is small. Thus, the solid-gas separation of the present invention is to perform the dust separation at the branch point between the inlet duct and the branch duct of the induced exhaust fan by utilizing the difference in the degree that the flow direction of the exhaust gas and the dust is changed by the branch point. This is the basic principle of the device.

Next, the relationship between the angle of the branch point between the inlet duct of the induced exhaust fan and the branch duct for dust separation in the solid-gas separation device of the present invention and the dust particle size will be described. FIG. 4 shows data obtained by measuring the particle size distribution of dust in the gas collected from the vent of the converter during operation by the ventilating hood in front of the furnace. According to this data, the emitted dust is
They are classified into small particles having a particle size of up to 10 μm and relatively large dust having a particle size of 50 μm or more. In the solid-gas separation device of the present invention, the gas flow rate in the gas duct 5 and the angle of the branch point shown in FIG. The relative angle between the inlet duct 9 of the induced exhaust fan 6 and the branch duct 10 for dust separation, which is the mainstream, greatly affects the performance of the solid-gas separation device of the present invention. FIG. 5 shows the result of calculating the particle trajectory inside the inner wall surface of the duct in order to design a flow path shape having a small pressure loss and good separation performance. Although the gas flow rate in the gas duct 5 changes due to the unsteady operation of the converter, it is approximately 10 to 15 m / s.
And a gas flow rate of 10 to 15 m /
In s, dust having a particle size of 50 μm is deflected to 20 to 30 degrees, so if the angle of the branch point is set to 20 to 30 degrees,
Since particles having a diameter of 50 μm or more are not deflected to an angle larger than the angle, dust having a large particle diameter is distributed to a branch duct 1 for dust separation.
Go inside 0.

As shown in FIG. 1, the branch duct 10 for dust separation is disposed straight up to the position of the water tank 12, and its end is bent downward and guided into the water tank 12 to be sealed. The water tank 12 is provided with a slurry pump 14 having a slurry pump 14 and a manual valve 15 as a slurry stirring / discharging device 13, and a slurry return pipe 17 branched downstream of the slurry pump 14 is provided at the bottom of the water tank 12. An agitation nozzle 18 is provided at the end of the guide. Further, in the water tank 12, a water level gauge 20 is provided in the water tank 12 as a seal water replenishing device 19, and a seal water supply pipe 22 provided with a motor-operated valve 21 which is opened and closed by detecting the water level by the water level meter 20 is provided. ing.

A branch duct 10 for dust separation shown in FIG.
The horizontal distance L from the branch point to the entrance of the water tank 12 needs to be large enough to prevent abrasion of the bent portion 11 of the branch duct 10 due to dust particles. Assuming that the dust particles have a horizontal velocity Vm / s at the upper part of the duct at the branch point, the time t to reach the lower part of the duct by sedimentation due to gravity is given.
Is

[0020]

(Equation 3)

## EQU1 ## Therefore, a horizontal distance L from the branch point of the branch duct 10 for dust separation to the entrance of the water tank 12 is obtained.
Should be designed so that L = about 5d.

The large-diameter dust entering the dust separating branch duct 10 does not wear the bent portion 11 of the branch duct 10 toward the water tank 12 shown in FIG.
Collected in the seal water inside. In the water tank 12, the slurry pump 14 is driven so that dust does not settle and accumulate, and the slurry is ejected from the agitation nozzle 18 via the slurry return pipe 17 to constantly stir the inside of the water tank 12. If dust accumulates to some extent in the aquarium 12,
The manual valve 15 of the slurry discharge pipe 16 is opened to discharge the slurry, and the slurry is dehydrated and collected by a wet dust processing system (not shown). In accordance with the drop in the water level in the water tank 12, the water level meter 20
, A detection signal is sent to the motor-operated valve 21, the motor-operated valve 21 is opened, and the seal water is supplied into the water tank 12 by the seal water supply pipe 22. Seal depth is always ensured.

[0023]

As can be seen from the above description, according to the solid-gas separation device of the present invention, the exhaust gas and the dust in the exhaust gas are separated at the branch between the inlet duct of the induced exhaust fan and the branch duct for dust separation. Can be separated by the interaction of the fluid force due to the difference between the inertia force of the two and the turning of the flow direction. In particular, the upward inclination angle θ of the inlet duct of the induced exhaust fan with respect to the branch duct for dust separation is approximately 20 ° to 30 °. °, the exhaust gas and the dust can be efficiently separated. Therefore,
Wear of the casing and the impeller of the induced exhaust fan can be reduced, and the life of the induced exhaust fan can be extended. Further, the maintenance cost of the induced exhaust fan can be reduced. Further, the dust removal capability of the existing bag filter downstream of the induced exhaust fan has a margin, and the consumption of the filter portion of the bag filter can be reduced.

Further, in the solid-gas separation device of the present invention in which the horizontal distance of the branch duct for dust separation is set to about five times the height of the inside of the duct, the dust particles at the bent portion of the branch duct to the water tank are provided. Wear can be prevented. Further, the end of the branch duct was guided into the water tank and sealed, and in the solid-gas separation device of the present invention in which the water tank was provided with a slurry stirring / discharging device and a seal water replenishing device, the end was always collected in the water tank. The slurry can be efficiently discharged while preventing sedimentation and accumulation of dust, and the seal water can be automatically supplied into the water tank, so that the seal depth always equal to or more than the negative pressure of the induced exhaust fan can be secured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a ventilation dust collecting facility of a steelmaking plant equipped with a solid-gas separation device of the present invention.

[Figure 2] exhaust gas to obtain impulse F by attracting exhauster, whereby an explanatory view of obtaining the theta ₁ angle to the traveling direction until now.

FIG. 3 shows that dust particles obtain impulse F by an induced exhaust fan and θ
FIG. 4 is an explanatory diagram when an angle of ₂ is obtained.

FIG. 4 is a graph showing data obtained by measuring a particle size distribution of dust in a gas collected from a vent of a converter during operation by a ventilating hood in front of a furnace.

FIG. 5 is a graph showing a relationship between dust particle diameter and dust deflection degree.

FIG. 6 is an explanatory diagram for setting a horizontal distance of a branch duct for dust separation in the solid-gas separation device of the present invention.

FIG. 7 is a view showing a conventional example of a ventilation dust collecting facility in a steelmaking factory.

FIG. 8 is a cross-sectional view showing a duct structure of a conventional dust collector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Converter 2 Skirt 3 Hood 4 Ventilation hood in front of furnace 5 Gas duct 6 Induction exhaust fan 7 Bag filter 8 Dispersion chimney 9 Inlet duct of induction exhaust fan 10 Branch duct for dust separation 11 Bend of branch duct 12 Water tank 13 Slurry stirring / Discharge device 14 Slurry pump 15 Manual valve 16 Slurry discharge pipe 17 Slurry return pipe 18 Agitation nozzle 19 Seal water replenishment device 20 Water level gauge 21 Motorized valve 22 Seal water supply pipe S Branch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C21C 5/40 C21C 5/40 Z F Term (Reference) 4D031 AB22 AB29 BA04 DA04 EA03 4D032 AA21 BA05 CA01 4K056 AA02 BA06 CA02 DB13 DB27 DC01 4K070 CA11 CA12

Claims (4)

[Claims] 1. A branch duct for dust separation is provided upstream of an inlet duct of an air intake and ventilation fan of a ventilation dust collecting facility, and the branch duct is connected so as to communicate with a gas duct upstream of a branch portion in a straight line. The inlet duct of the exhaust fan is connected to the upper surface of the upstream gas duct at an inclination at the branch of the branch duct by inclining upward, and at the branch, exhaust gas and dust in the exhaust gas are connected.
A solid-gas separation device characterized in that the separation is performed by the interaction of a fluid force due to a difference in inertial force between the two and a change in flow direction. 2. The solid-gas separation device according to claim 1,
A solid-gas separation apparatus characterized in that an upward inclination angle [theta] of an inlet duct of an induced exhaust fan with respect to a branch duct for dust separation is approximately 20 to 30 [deg.]. 3. The solid-gas separation device according to claim 1, wherein the horizontal distance L of the branch duct for dust separation is about five times the height in the branch duct. apparatus. 4. The solid-gas separation device according to claim 1, wherein the end of the branch duct for dust separation comprises:
A solid-gas separator, wherein the solid-gas separator is guided and sealed in a water tank, and the water tank is provided with a slurry stirring / discharging device and a seal water replenishing device.