JP3756432B2 - Gas recovery method during dephosphorization operation in converter exhaust gas treatment facility for decarburization blowing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas recovery method for recovering unburned gas generated from a converter during a dephosphorization operation in a converter exhaust gas treatment facility for decarburization blowing.
[0002]
[Prior art]
In recent converter operations, so-called pre-treatment furnaces that have undergone desiliconization, desulfurization, and dephosphorization treatment are used for the purpose of improving the efficiency of steelmaking, reducing the amount of slag, and improving productivity. Operations that only do are increasing. More recently, in order to further improve the efficiency, desiliconization and desulfurization are processed in separate facilities, and the first half of the useful life of one converter is decarburized and blown down. A method of using a converter by switching to dephosphorization blowing is adopted. However, according to this method, in dephosphorization blowing, the amount of oxygen blown into the converter is 25% or less and the amount of generated gas is extremely low, 15% or less, and the control of the furnace pressure control damper is performed. Since it is out of the range, the operation is performed by increasing the amount of air sucked from between the converter furnace opening and the skirt. For this reason, all the CO gas by the decarburization reaction generated in parallel with the dephosphorization reaction is burned without being recovered, and is diffused into the atmosphere.
[0003]
In order to recover CO gas by decarburization reaction that is generated side by side with the above dephosphorization reaction as a valuable resource, “Non-combustion in a pure oxygen top blow converter” is disclosed in JP-A-53-53504. In the “exhaust gas recovery method”, an ore that generates CO ₂ and a carbon-containing substance are introduced during blowing and the amount of generated gas is increased by utilizing the reaction of CO ₂ + C → 2CO. However, in this method, limestone or dolomite ore is introduced as an ore that generates CO ₂ , so that it is difficult to adopt for dephosphorization operation by a converter for the purpose of reducing the amount of slag and improving the efficiency of the converter operation. In order to increase the amount of gas, a large amount of ore and carbon-containing materials are required. Further, in carrying out the dephosphorization operation, the dephosphorization efficiency is decreased, the amount of slag is increased, the generation of forming is increased and the metallurgical effect is increased. There's a problem.
[0004]
On the other hand, the converter exhaust gas treatment facility is equipped with a variable throat type venturi scrubber as a secondary dust collector, which converts the converter generated gas that constantly fluctuates due to the reaction in the converter to the converter furnace outlet and the exhaust gas treatment facility inlet. It has a so-called furnace pressure control function of adjusting the gas pressure (generally referred to as the furnace pressure) at the converter furnace opening and the skirt portion so that the amount of intake air and the amount of blown gas between the skirt and the skirt are minimized. This variable throat type venturi scrubber as a furnace internal pressure control damper decreases the furnace internal pressure as the amount of gas generated in the converter decreases. Therefore, the furnace internal pressure is set to the furnace internal pressure set value (minimizing the intake air at the furnace opening, It is normally set to plus a few millimeters of water to increase the pressure) and operates in the closing direction. However, the variable throat type venturi scrubber as a furnace pressure control damper has a slight gap even when it is fully closed, and there is also a gap of several millimeters between the damper vane plate and the casing. When the damper opening becomes extremely close and the damper opening is nearly fully closed, the ratio of the amount of leaked gas from between the damper vane and the casing to the amount of gas passing through the damper funnel increases, and furnace pressure control is substantially performed. No state.
[0005]
[Problems to be solved by the invention]
Therefore, in view of the above-described various problems, the present invention provides an appropriate control of the furnace pressure when performing dephosphorization operation in a decarburization blowing converter exhaust gas treatment facility, and blowing oxygen specified in the dephosphorization operation. A gas recovery method capable of recovering the generated gas as a valuable gas without being burned without increasing the amount and auxiliary materials, that is, without introducing new materials into the converter for increasing the amount of generated gas. It is something to be offered.
[0006]
[Means for Solving the Problems]
The gas recovery method at the time of dephosphorization operation in the converter exhaust gas treatment facility for decarburizing and blowing of the present invention for solving the above-mentioned problem is the secondary collection at the time of dephosphorization operation in the converter exhaust gas treatment facility for decarburization and blowing. By spraying sealing water from the inlet of the furnace pressure control damper, which is a variable throat type venturi scrubber of the duster , to both ends of the furnace pressure control damper, the control range of the furnace pressure control damper is reduced to a low air volume range. And the gas generated from the converter is recovered unburned through the furnace pressure control damper.
[0008]
The amount of the sealing water to be sprayed is preferably automatically adjusted according to the opening of the furnace pressure control damper.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the gas recovery method at the time of dephosphorization operation in the converter exhaust gas treatment facility for decarburization blow smelting of the present invention is described. First, a converter exhaust gas treatment facility planned for decarburization blowing will be described with reference to FIG. 1. 1 is a converter and 2 is a converter exhaust gas treatment facility. The converter exhaust gas treatment facility 2 is provided with a skirt 3 that can be moved up and down in the hood 4 so as to seal the converter furnace port. The hood 4 has an oxygen blowing lance 5 for decarburization blowing and an auxiliary material inlet 6. Is provided. The hood 4 is followed by a radiant heat transfer section 7, a primary dust collector 9, and a secondary dust collector 10, and an exhaust gas flow meter 12 and an induction exhaust fan 13 are further provided in a downstream exhaust gas duct 11. A gas recovery duct 15 is provided at one end via a three-way valve 14 at the end of the duct 11, and a diffusion chimney 16 is provided at the other end. The gas recovery duct 15 is provided with a rotary water seal valve 17 in the middle, and a gas holder 18 at the end. Reference numeral 19 denotes a furnace pressure detector provided in the vicinity of the skirt 3 of the hood 4, and this furnace pressure detector 19 sends a furnace pressure detection signal to the control device 20, and the control device 20 receives the furnace pressure detection signal. The opening degree of the furnace pressure control damper 21 which is a variable throat type venturi scrubber of the secondary dust collector 10 is controlled.
[0010]
The converter exhaust gas treatment facility 2 configured as described above closes the converter furnace port by operating the induction exhaust fan 13 with high-concentration CO gas generated by decarburizing and blowing the hot metal charged into the converter 1. The skirt 3 and the hood 4 are introduced into the radiant heat transfer section 7 where heat is recovered from the high-temperature CO gas, and the CO gas that has fallen in temperature is introduced to the primary dust collector 9 and the secondary dust collector 10. After removing the dust in the CO gas, the CO gas is passed through the exhaust gas duct 11, passed through the exhaust gas flow meter 12 and the induction exhaust fan 13, and then passed through the gas recovery duct 15 switched by the three-way valve 14, and the rotary type water seal It collects in the gas holder 18 through the valve 17. Further, the CO gas having a low concentration in the initial stage and the final stage of the blowing is switched to the diffusion chimney 16 side by the three-way valve 14, and is diffused into the atmosphere after combustion at the top of the diffusion chimney 16.
[0011]
By the way, the variable throat type venturi scrubber shown in FIG. 2 used as the furnace internal pressure control damper 21 of the secondary dust collector 10 in the converter exhaust gas treatment facility 2 having the above-described configuration and operation has been investigated by the present inventors. The control range of the variable venturi scrubber is that the range ability is 100: 7 under normal conditions, that is, it is difficult to control at an opening of 7% or less (70,000 m ³ N / h in gas amount), and the variable throat type It has been found that the opening of the furnace pressure control damper, which is a venturi scrubber, the amount of gas passing through the throat portion, and the amount of gas leaking from between the end of the damper blade plate and the casing are in the relationship shown in the graph of FIG. In FIG. 3, the solid line indicates the total amount of gas passing through the furnace pressure control damper, and the broken line indicates the amount of leak gas from between the blade end and the casing.
[0012]
The pressure loss of the variable throat type venturi scrubber is
^{ΔP = f × (ν 2 /} 2g) × γ
ΔP: Pressure loss f: Resistance coefficient ν: Gas flow velocity g: Gravitational acceleration γ: Fluid density relationship is established, and the resistance coefficient f1 of the throat portion is as shown in the graph of FIG. Although changed, it has been found that the resistance coefficient f2 between the end portion of the damper blade plate and the casing is constant without depending on the damper opening.
[0013]
From the above results, it has been found that if the resistance coefficient is set to f1 <f2 in a region where the damper opening is small, the amount of leakage between the end portion of the damper blade plate and the casing can be reduced and the range ability can be reduced. The present invention has been made on the basis of this finding, and in order to establish the resistance coefficient f1 <f2, when performing dephosphorization operation, a furnace pressure control damper which is a variable throat type venturi scrubber of the secondary dust collector 10 1 is shown in FIG. 1 with a part of the water 21 sealed to expand the control range of the furnace pressure control damper 21 to a low air volume range, and the generated gas from the converter 1 remains unburned through the furnace pressure control damper 21. It is intended to be collected in the gas holder 18.
[0014]
A specific means for water-sealing a part of the furnace pressure control damper 21 is a spray nozzle above both ends of the furnace pressure control damper 21 which is a variable throat type venturi scrubber of the secondary dust collector 10 shown in FIG. The corner seal pipe 23 is provided with the bottom 22 facing downward, the seal water adjustment valve 24 is provided in the corner seal pipe 23, and the seal water adjustment valve 24 is provided from the opening degree transmitter 25 provided in the furnace pressure control damper 21. The seal water 26 to be supplied and sprayed is increased or decreased by automatically adjusting according to the opening signal. The opening transmitter 25 is fixed to a shaft 31 of a small sector gear 30 that meshes with a sector gear 29 fixed to one end of a damper shaft 28 of one damper blade plate 27 as shown in FIG. When one of the damper blades 27 is opened, the opening is transmitted to the small sector gear 30 via the sector gear 29 on the damper shaft 28 and input to the opening transmitter 25 on the shaft 31. Here, the opening signal is transmitted to the seal water adjustment valve 24.
[0015]
When performing the dephosphorization operation by the water sealing means having such a configuration, the seal water 26 is sprayed from the inlet of the furnace pressure control damper 21 toward both ends of the furnace pressure control damper 21 as shown in FIG. As shown in the figure, a seal region 34 is formed in the gap 33 between the both ends of the damper blades 27 and 27 ′ and the casing 32 and sealed, and the gas flow rate passing through the furnace pressure control damper 21 and the gas leaking from the gap 33 are shown. The flow rate was as shown in the graph of FIG. 7, and control up to a gas amount of 50000 m ³ N / h became possible. Further, from this embodiment, in the region where the opening of the furnace pressure control damper 21 is opened by 10% or more, the gas flow velocity at the inlet of the throat portion 35 becomes faster, so that the sprayed seal water 26 flows into the throat portion 35 and the gap 33 The water sealing effect against is lost. Accordingly, it has been found that increasing the amount of the sealing water 26 sprayed to increase the water sealing effect increases the pressure loss of the throat portion 35 and conversely reduces the dust removal performance. The opening 10% of the furnace pressure control damper 21 in actual operation is within the control range ability, and the seal water 26 is actually required in the gap 33 when the opening of the furnace pressure control damper 21 is 7% or less. At that time, the amount of sealing water 26 required was 5 to 10 m ³ N / h. During the dephosphorization operation, the necessary amount of sealing water 26 is adjusted according to the opening of the furnace pressure control damper 21, that is, according to the opening signal from the opening transmitter 25. Is automatically adjusted, the seal water 26 sprayed from the spray nozzle 22 of the corner seal pipe 23 is increased or decreased, and the gas generated from the converter 1 is shown in FIG. 1 as unburned through the furnace pressure control damper 21. It is collected in the gas holder 18.
[0016]
【The invention's effect】
As can be seen from the above description, according to the present invention, the furnace pressure control can be automatically and accurately performed at the time of dephosphorization operation in the converter exhaust gas treatment facility for decarburization blowing, and also specified in the dephosphorization operation. Without increasing the amount of blown oxygen and auxiliary materials, that is, without introducing new materials into the converter to increase the amount of generated gas, therefore, the dephosphorization efficiency decreases, the slag amount increases, and the forming The generated gas from the converter during the dephosphorization operation can be recovered as a valuable gas without being burned, without causing any generation or metallurgical problems. In addition, the wear of the damper blade plate and casing caused by an increase in the amount of leak gas between the end of the damper blade plate and the casing when the furnace pressure control damper has a low opening degree is reduced, and the life of the furnace pressure control damper is reduced. Can also be extended significantly.
[Brief description of the drawings]
FIG. 1 is a system diagram of a converter exhaust gas treatment facility.
2 is a view showing a furnace pressure control damper which is a variable throat type venturi scrubber of a secondary dust collector in the converter exhaust gas treatment facility of FIG. 1;
3 is a graph showing the relationship between the opening of the furnace pressure control damper of FIG. 2, the amount of gas passing through the throat, and the amount of gas leaking from between the end of the damper blade plate and the casing.
FIG. 4 is a graph showing a resistance coefficient ratio in the relationship between the opening degree and resistance of a furnace pressure control damper.
FIG. 5 is a diagram showing specific means for water-sealing a part of the furnace pressure control damper when carrying out the gas recovery method during the dephosphorization operation in the converter exhaust gas treatment facility of the present invention.
6 is a cross-sectional view taken along line AA in FIG.
FIG. 7 is a graph showing the relationship between the opening of the furnace pressure control damper, the amount of gas passing through the throat, and the amount of gas leaking from the gap.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Converter 2 Converter exhaust gas treatment equipment 3 Skirt 4 Hood 5 Oxygen blowing lance 6 Sub raw material inlet 7 Sub radiation heat transfer part 9 Primary dust collector 10 Secondary dust collector 11 Exhaust gas duct 12 Exhaust gas flow meter 13 Fan 14 Three-way valve 15 Gas recovery duct 16 Radiation chimney 17 Rotary type water seal valve 18 Gas holder 19 Furnace pressure detector 20 Controller 21 Furnace pressure control damper 22 Spray nozzle 23 Corner seal piping 24 Seal water adjustment valve 25 Opening transmitter 26 Seal water 27, 27 'Damper vane plate 28 Damper shaft 29 Fan gear 30 Small fan gear 31 Shaft 32 Casing 33 Clearance 34 Sealing area 35 Throat part

Claims (2)

During dephosphorization operation in converter exhaust gas treatment equipment for decarburization blowing, seal water is sprayed from the inlet of the furnace pressure control damper, which is a variable throat type venturi scrubber of the secondary dust collector , to both ends of the furnace pressure control damper The decarburization blow smelting is characterized in that the control range of the furnace pressure control damper is expanded to a low air volume region by water sealing, and the gas generated from the converter is recovered unburned through the furnace pressure control damper. Recovery method during dephosphorization operation in converter exhaust gas treatment facility The gas recovery method during dephosphorization operation in the converter exhaust gas treatment facility for decarburization blowing according to claim 1 , wherein the amount of the sealing water is automatically adjusted according to the opening of the furnace pressure control damper.

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