TW202144591A - Mechanical stirring-type desulfurization system - Google Patents

Abstract

To provide a mechanical stirring-type desulfurization system which is capable of detecting the level of the surface of a bath of hot metal using a simple method and automatically adjusting a lance to the optimum position in accordance with the detected bath surface level. The present invention is characterized by comprising a control unit 14 that controls movement such that the tip end of a top lance 10 reaches a position at a prescribed height from the surface of the bath in a hot metal ladle 2, wherein the control unit 14 is provided with: a movement distance calculating means that calculates the freeboard [Delta]H of the hot metal ladle 2 from the inner diameter D of the hot metal ladle 2 and the inclination angle of the hot metal ladle 2 during slag removal, which is a pretreatment before desulfurization, and calculates a movement distance L for the top lance on the basis of the calculated freeboard; and a lance driving means that, on the basis of the calculated movement distance L, drives the top lance 10 such that the tip end of the top lance reaches a position at a prescribed height from the bath surface in the hot metal ladle 2.

Description

Mechanical stirring desulfurization system

The present invention relates to a mechanically agitated desulfurization system comprising a mechanically agitated desulfurization device and a blowing pipe for gas blowing for blowing a desulfurizing agent into the mechanically agitated desulfurization device.

As a typical device used for dephosphorizing and desulfurizing molten iron, a mechanical stirring type desulfurizer is known, which injects a dephosphorizing and desulfurizing agent into a refining vessel in which molten iron is accommodated, and uses The stirring impeller mechanically stirs the molten iron.

In this facility, as a method for adding the desulfurizing agent, the gravity drop method is conventionally used. In this method, when adding a desulfurizing agent, a part of the desulfurizing agent scatters and is attracted by the dust collector, or the desulfurizing agent agglomerates and causes Since the desulfurization efficiency is lowered, there is a problem that the addition yield (yield) of the desulfurizer or the like is low. Therefore, the following method is used, that is, the liquid surface of the molten iron to be stirred is sprayed at high speed and continuously with a conveying gas such as argon gas and nitrogen gas through a cylinder called a top blowing pipe, thereby to A desulfurizing agent is added into the molten iron (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-179690 [Patent Document 2] Japanese Patent Laid-Open No. 2004-301362

[Problems to be Solved by Invention]

In the above-mentioned method of blowing the desulfurizing agent toward the liquid surface of molten iron using the top blowing pipe, the height of the blowing pipe relative to the liquid surface level greatly contributes to the desulfurization efficiency. For example, during projection, if the distance between the blow pipe and the liquid surface is long (800 mm or more), the dust collector will be sucked, and the input amount of the desulfurizing agent will be reduced, so the desulfurization efficiency will be deteriorated. On the contrary, if the distance between the blowpipe and the liquid surface is close (below 400mm), the front end of the blowpipe will be melted by molten iron, which will shorten the service life of the blowpipe. Therefore, it is important to adjust the height of the blow pipe relative to the liquid level (recommended blow pipe ~ liquid level height: 500~700mm).

In addition, the amount of molten iron to be processed is different each time, and furthermore, the difference in the shape of the processing pot caused by the base metal attached to the inner side of the pot causes the liquid level of each treatment to fluctuate greatly. , so it is necessary to measure the liquid level every time. Conventionally, as a method of measuring the liquid level of molten iron, the following methods are known. (1) A method of obtaining the height (liquid level) by dividing the weight of the molten iron by the specific gravity to obtain the volume, and then dividing it by the bottom area of the molten iron pot. However, according to this method, when the base metal or the like adheres to the inner side of the pot (refractory), the bottom area becomes smaller, or conversely, when the inner side of the pot is worn out, the bottom area becomes larger, so there are The problem of poor precision.

(2) A method of measuring the liquid level using a sensor that transmits or receives microwaves from the opening direction of the upper part of the melting pot However, in actual measurement, in order to prevent failures caused by radiant heat from molten iron, it is necessary to take heat-resistant measures such as inserting a heat-resistant plate to surround the sensor to suppress the internal temperature rise. The dust of the desulfurizing agent or the like flies up and adheres and accumulates on the heat-resistant plate, and the microwave is attenuated, so that it becomes impossible to measure the liquid level, and these problems exist.

(3) The method of judging the brightness change of the liquid surface when the stirring impeller is immersed in molten iron by visual inspection or a camera However, in the case of visual inspection, the operator must always monitor the liquid level, so there is a problem from the viewpoint of work load and labor saving. In addition, in the case of using a camera for determination, there is a problem that the detection accuracy varies depending on the properties of the slag floating on the surface of the molten iron, the amount of production, and the state of distribution. Furthermore, there is a high risk of the camera malfunctioning due to the surrounding environment.

In view of the above-mentioned conventional problems, the following method has been proposed (refer to Patent Document 2), that is, to detect the splash generated at the moment when the front end of the stirring impeller comes into contact with the liquid surface of molten iron, The molten iron level is measured by the value of the encoder installed on the motor shaft for the stirring impeller raising and lowering. However, in this method, the splashes generated will cause the loss of refractories in the iron melting pot, thereby reducing the yield of steel production, and the surveillance cameras for splash detection are prone to failure at high temperatures. These problems are unavoidable. The present invention is developed in view of the above-mentioned problems, and its purpose is to provide a mechanical stirring desulfurization system, which can use a simple method to detect the liquid level of molten iron, and according to the detected liquid level The liquid level will automatically adjust the blowpipe to the best position. [Technical means to solve problems]

The present invention relates to a mechanically agitated desulfurization system equipped with a mechanical stirring type desulfurization device (hereinafter referred to as a "desulfurization device") and a top blowing pipe. The desulfurizing device is provided with a stirring impeller and an iron melting pot. The iron-melting pot of the desulfurization device projects a desulfurizing agent, and this system performs desulfurization treatment of the molten iron thrown into the iron-melting pot. The above object of the present invention is achieved by a mechanical agitation desulfurization system having the following characteristics. The system further includes a control unit for causing the front end of the top blowing pipe to reach a predetermined height from the liquid level of the iron melting pot. The movement control is performed according to the position of the (H), and the control unit includes a movement distance calculation means and a blower drive means, and the movement distance calculation means is based on the pretreatment of the desulfurization treatment, that is, the slag removal treatment. The tilt angle (θ) of the iron pot and the inner diameter (D) of the iron melting pot are used to calculate the freeboard (ΔH) of the iron melting pot, and the movement of the top blowing pipe is calculated according to the calculated water outlet height. The distance (h), the blow pipe driving means, is based on the calculated moving distance to drive the top blow pipe so that the front end of the top blow pipe reaches a position at a predetermined height (H) from the liquid level of the iron melting pot. . [Effect of invention]

According to the mechanical stirring desulfurization system of the present invention, the liquid level of molten iron can be detected by a simple method, and the blow pipe can be automatically adjusted to the best position according to the detected liquid level.

Hereinafter, the mechanical stirring desulfurization system of the present invention (hereinafter simply referred to as "desulfurization system") will be described in detail with reference to the drawings. In general, the mechanical stirring type desulfurization treatment program (hereinafter simply referred to as "desulfurization treatment program") is to desulfurize molten iron in the order of pretreatment, desulfurization treatment, and posttreatment. The pretreatment is a step of removing the slag (slag) floating on the liquid surface by a slag skimmer in order to improve the desulfurization efficiency before the desulfurization treatment. FIG. 1 shows the state of the pretreatment, the steps of which are as follows. (a) Using the tilting trolley 1, tilt the molten iron pot 2 to the maximum angle that does not cause the molten iron to overflow. The tilt angle θ at this time is stored in a storage device (not shown). (b) The slag floating on the liquid surface is scraped off by the slag discharger 3 and moved to the slag pot 4 . After the slag was removed, the inclination of the iron melting pot was returned to its original state, and the process was transferred to the next step.

FIG. 2 shows a driving method for tilting the melting pot 2 . FIG. 2(A) shows the case where the actuator 5 for driving the tilting of the melting pot 2 is electric, and a rotator is provided on the axis of the tilting gear. FIG. 2(B) shows the case where the actuator 5 is hydraulically driven, and the tilt angle is changed by extending and contracting the rod of the hydraulic cylinder. Each is provided with an encoder (not shown), and converts a mechanical displacement amount (angle change or expansion and contraction amount) into an electrical signal. The output signal of the encoder is stored in a storage means not shown, and the tilt angle can be obtained by reading the signal.

Next is the desulfurization treatment process. Figure 3 shows a general desulfurization treatment system. The desulfurization treatment system includes a molten iron stirring part, a blow pipe projection part, and a molten iron pot 2 . The molten iron stirring part includes a stirring impeller 6, a stand and a lifting motor 9. The stand system includes: a rotary driving motor 7 of the stirring impeller 6, and a lifting and lowering of the rotary driving motor 7 and the up and down of the stirring impeller 6 The frame body 8 and the motor 9 for raising and lowering the frame body are pulled by ropes. The blow pipe projection part includes a top blow pipe 10 (hereinafter referred to as "blow pipe") and a blow pipe driving means. The blow pipe 10 uses a conveying gas such as argon, nitrogen, etc. to move the desulfurizing agent toward the liquid surface of the molten iron being stirred. Continuously blowing and adding; the blowing pipe driving means has a blowing pipe driving motor 11, and the blowing pipe driving motor 11 adjusts the height of the blowing inlet of the blowing pipe by moving the blowing pipe 10 up and down in the direction of the arrow in the figure. The molten iron pot 2 is mounted on the tilting cart 1, and molten iron is put into it. In addition, the dust collector 12 is a device that attracts and collects the desulfurizing agent sprayed from the blowing pipe 10 and scatters into the air without reaching the iron melting pot 2 .

The desulfurization treatment is a treatment in which a desulfurizing agent is injected into molten iron and stirred to react the sulfur component in the molten iron with the desulfurizing agent. The procedure is as follows. (a) Drive the elevating motor 9 , lower the stirring impeller 6 to a predetermined height together with the elevating frame 8 to immerse it in molten iron, and stir the molten iron by the rotary drive motor 7 . (b) After the blowing pipe 10 is lowered according to the liquid level, the desulfurizing agent is projected from the front end of the blowing pipe, and the desulfurizing agent and molten iron are stirred and mixed to start the desulfurization reaction. (c) When the stirring is stopped, the desulfurizing agent combined with the sulfur component in the molten iron floats on the surface of the molten iron in the form of slag. The motor 9 for raising/lowering is driven, the impeller 6 is pulled out from the iron melting pot 2, and it transfers to the next post-processing. The post-treatment is a step of removing the slag floating on the surface of the liquid surface after the desulfurization treatment. The operation is the same as that of the pre-treatment. Since its operation is basically the same as that of the preprocessing, the detailed description will be omitted.

In Fig. 3, the distance H between the blow pipe and the liquid surface is a problem. Usually, when H is approximately 400 mm or less, the tip of the blow pipe may be melted due to molten iron heat and molten iron splashing. Conversely, when H is approximately 800 mm or more At this time, the desulfurizing agent scatters and is sucked by the dust collector 12, and there is a possibility that the input amount of the desulfurizing agent will decrease. Therefore, the position of the front end of the torch is usually adjusted so as to be about 500mm≦H≦about 700mm, and the factor affecting the position adjustment of the torch is the part not immersed in the molten iron, that is, the height of the water outlet height (ΔH ). Therefore, as long as this ΔH can be grasped in advance, it can be adjusted to an appropriate H.

投入鍋內之熔鐵量，縱使將傾動回復原狀也不會改變，因此出水高度部之空間的體積也不會改變。因此，

然而，顯然

因此成為

。 因此，可根據鍋的直徑D和傾動角θ來決定唯一的ΔH，而與熔鐵量無關。FIG. 4 is an explanatory diagram of a method for obtaining the height ΔH of the water outlet height portion of the iron melting pot from the tilt angle (θ) stored in the previous process. Fig. 4(A) is a case of a cylindrical container. The volume V of the space in the container can be expressed by the following formula when the tilting angle when inclined to the maximum angle at which the molten iron does not overflow is set to θ and the diameter of the container is set to D.

The amount of molten iron put into the pot will not change even if it is tilted back to its original state, so the volume of the space at the height of the water outlet will not change. therefore,

However, obviously

thus become

. Therefore, the unique ΔH can be determined according to the diameter D of the pan and the tilt angle θ, regardless of the amount of molten iron.

Next, Fig. 4(B) shows the actual situation of the molten iron pot, which is equivalent to providing the notch of the portion shown by the dotted line in the cylindrical container of Fig. 4(A), so the situation of Fig. 4(A) can be adopted. Same idea. From the tilt angle (θ) stored in the previous process, the height ΔH of the water outlet height portion of the iron melting pot can be obtained by using the above-mentioned formula 1.

The influence on the change of the inner diameter D of the iron melting pot is the loss of the refractory caused by the frequency of use of the iron melting pot, or the narrowing of the inner diameter D caused by the adhesion of the base metal. Usually it is the combination of these two parties that makes D change. Fig. 5 shows the case where the refractory on the inside of the iron melting pot has metal deposits attached to narrow the inner diameter D (Fig. A), and the case where the inner diameter D is widened due to the loss of the refractory inside (Fig. B) . Then, it was examined to what extent the height ΔH of the outlet height portion is affected by the change of the inner diameter D. In the following description, "the height of the water outlet height" is simply referred to as the "water outlet height". When D is changed by ΔD, the water outlet height ΔH' is calculated using the above formula 1,

。 對於θ為30°、40°、45°的情況(通常傾動角約30°，最大45°的程度)分別計算δ，而成為以下般。

亦即，縱使熔鐵鍋的內徑改變了200mm，就出水高度而言，甚至在傾動角最大45°的情況也僅有100mm的誤差，相較於較佳出水高度之範圍(500mm~700mm)的幅度，影響很小。Assuming that ΔD is set to a maximum of 200 mm (loss of 100 mm for the thickness of the refractory, and loss of 200 mm for the diameter), the increase in ΔH (δ) becomes

. For the cases where θ is 30°, 40°, and 45° (normally, the tilt angle is about 30°, about 45° at the maximum), δ is calculated respectively, and the result is as follows.

That is, even if the inner diameter of the iron melting pot is changed by 200mm, in terms of the water outlet height, even when the tilt angle is up to 45°, there is only a 100mm error, which is compared to the range of the best water outlet height (500mm~700mm) magnitude, the impact is small.

Figure 6 is a graph showing the relationship between the tilt angle (θ) and the water outlet height. It is presented in a visual way, as long as the tilt angle is the same, the effect of the loss of the melting pot is very small. For example, the position indicated by the arrow in the figure (θ=about 36°) shows that there are six types of loss states of the iron melting pot. Therefore, even if the water outlet height calculated using the inner diameter D of a standard molten iron pot (eg, a new pot) is used in all cases, the effect is small.

Next, the configuration and operation of the desulfurization system of the present invention will be described. Fig. 7 is a schematic diagram showing the structure of the desulfurization system of the present invention. Since the basic configuration is the same as that shown in FIG. 3, only the different parts will be described. The desulfurization system of the present invention is added to the conventional desulfurization system shown in FIG. 2 : the blowing pipe passes the detection sensor 13 (photoelectric sensor) and the blowing pipe driving motor 11 to control the moving distance of the blowing pipe the control unit 14 . The tilt angle θ is measured in the preprocessing stage, and is input to the control unit 14 and stored. In addition, as for the loss state of the pot, the actual measurement of the inner diameter D can be completed before the start of the pretreatment, and the measured value can be input, or when the degree of loss can be known empirically according to the number of times the pot is used, the use The number of times is converted into loss degree (mm).

因此

因為L₀ 的值可事先知道，又約500mm≦H≦約700mm，例如設定成H=600mm，L成為ΔH的一次函數。 因此，藉由根據傾動角θ而利用上述式1算出出水高度ΔH，能讓吹管自動移動到最佳位置。The automatic control performed by the control part 14 moves the position of the front end of the blow pipe to a predetermined height (H) from the liquid surface, and stops it there. In order to do so, the blowpipe must be moved to this position, and the descending distance L (referring to the vertical distance from the passing of the blowpipe through the detection sensor 13) can be obtained by the following equation. That is, if the height from the upper end of the pot to the point where the blowpipe passes the detection sensor 13 is set to L ₀ , and the water outlet height of the pot is set to ΔH, then

therefore

Because _{the value of L 0} can be known in advance, and about 500mm≦H≦about 700mm, for example, if H=600mm, L becomes a linear function of ΔH. Therefore, the blowpipe can be automatically moved to the optimum position by calculating the water discharge height ΔH by the above-mentioned formula 1 based on the tilt angle θ.

表示。亦即成為

。 藉由讓吹管在行進方向移動該h的距離，結果能讓其移動所期望的下降距離L。 吹管之行進方向的移動距離h之偵測，可將光電感測器及未圖示的吹管升降旋轉器(編碼器)結合。 利用升降旋轉器(編碼器)來測定吹管遮住光電感測器13的位置，並將從那裡起算的移動距離用編碼器計測。 又也能取代編碼器而採用以下方法，亦即，在吹管旁邊設置刻度基準，利用攝像機讀取刻度來計測長度。When the angle between the blowpipe and the vertical direction is α, the relationship between the descending distance L of the front end of the blowpipe and the actual moving distance h of the blowpipe in the travel direction can be used.

Express. that is to become

. By moving the blowpipe by the distance h in the direction of travel, it is possible to move it by the desired descending distance L as a result. The detection of the moving distance h in the traveling direction of the blowpipe can be combined with a photoelectric sensor and a blowpipe lifting and lowering rotator (encoder) not shown. The position where the blowpipe shields the photoelectric sensor 13 is measured with a lifter (encoder), and the moving distance from there is measured with the encoder. In place of the encoder, a scale reference may be provided beside the blow pipe, and the scale may be read by a camera to measure the length.

In order to reduce the influence of the water outlet height ΔH caused by the loss state of the pot, as one method, the relationship between the water outlet height value and the tilt angle calculated in advance according to different loss states can be tabulated in advance, and the table can be switched to use as needed. . FIG. 8 is a table obtained by tabulating the relationship between the tilt angle (θ) and the water outlet height according to the different loss states of the pot. This is an example. Although it is more accurate to set the angle every 1 degree, it is represented by every 5° due to the space on the page. It can be seen that as long as the angle is the same, the change of the water outlet height ΔH caused by the loss state is very small. For example, when the tilt angle is 30°, even with a loss of 100mm, the water outlet height only changes by 58mm. Also in the case of 45°, even if 100mm of loss occurs, the water outlet height only changes by 100mm, which has little impact compared to the range of the optimal water outlet height (500mm~700mm).

FIG. 9 is an example of a flowchart showing the flow of control performed by the control unit 14 . As a premise, the wear state (loss degree) of the molten iron pot used on the day and the tilt angle (θ) measured in the previous process are input and stored in advance. When the program of the control unit 14 is started, first, the CPU (not shown) of the control unit 14 reads the degree of wear (or the number of times of use) of the melting pot according to a predetermined program ( S1 ). Next, the tilt angle θ is read (S2). Referring to the table of the water outlet height corresponding to the loss degree of the iron melting pot (for example, the table shown in FIG. 8 ), read the water outlet height ΔH corresponding to the tilt angle θ ( S3 ).

According to the read water outlet height ΔH, the descending distance L of the blowing pipe is calculated (S4). For calculation of the descending distance L of the blowpipe, the above-mentioned Equation 3 was used. Next, the moving distance h of the torch is calculated using the above-mentioned formula 4. The blowpipe drive motor 11 is driven to start driving the blowpipe (S5). After the blowpipe passes the blowpipe detection sensor 13 (Yes in step S6 ), the measurement of the moving distance of the blowpipe is started ( S7 ). The moving distance from the point when the blowpipe covers the photoelectric sensor 13 is measured by the lifter (encoder). When the moving distance of the blow pipe reaches the moving distance h obtained by the above-mentioned formula 4 (Yes in step S8 ), the driving (movement) of the blow pipe is stopped ( S9 ). At the position where the blow pipe is stopped, the projection of the desulfurizing agent from the blow pipe is started (S10).

According to the present invention, the distance from the desulfurizing agent projection blow pipe to the liquid surface can be kept constant in all treatments, and the optimum distance can be uniformly secured regardless of the conditions. In this way, the desulfurizing agent is not attracted by the dust collecting device, and the desulfurizing agent can efficiently enter into the stirring molten iron, so that stable desulfurization treatment can be performed. Based on this effect, the success rate of desulfurization treatment can be made very high. Furthermore, the melting loss at the front end of the blowing pipe due to the proximity to the molten iron surface is reduced, which can significantly prolong the service life of the blowing pipe.

1: Tilt trolley 2: melting pot 3: Slag discharger 4: Slag pot 5: Actuator 6: Stirring impeller 7: Motor for rotary drive 8: Lifting frame 9: Lifting motor 10: Top blow pipe 11: Blowpipe drive motor 12: Dust collection device 13: The blowpipe passes the detection sensor 14: Control Department

[ Fig. 1 ] shows the state of the treatment before the desulfurization treatment. [FIG. 2] (A) and (B) show the driving method for tilting the melting pot. [Fig. 3] shows a general desulfurization treatment system. [Fig. 4] (A) and (B) are explanatory diagrams of a method for obtaining the height ΔH of the water outlet height portion of the molten iron pot from the tilt angle (θ) stored in the previous process. [FIG. 5] (A) shows the case where the refractory inside the melting pot is made of metal adhered to narrow the inner diameter D, and FIG. 5(B) shows that the inner refractory is lost and the inner diameter D widens Case. [ Fig. 6 ] is a graph showing the relationship between the tilt angle (θ) and the height (ΔH) of the water outlet height. [ Fig. 7 ] is a schematic diagram showing the structure of the mechanically agitated desulfurization system of the present invention. [Fig. 8] The relationship between the tilt angle (θ) and the height (ΔH) of the water outlet height portion is tabulated according to the different loss states of the pot. FIG. 9 is an example of a flowchart showing the flow of control performed by the control unit.

1: Tilt trolley

2: melting pot

6: Stirring impeller

7: Motor for rotary drive

8: Lifting frame

9: Lifting motor

10: Top blow pipe

11: Blowpipe drive motor

12: Dust collection device

13: The blowpipe passes the detection sensor

14: Control Department

Claims (2)

A mechanical stirring desulfurization system is provided with a mechanical stirring desulfurization device (hereinafter referred to as "desulfurization device") and a top blowing pipe. The above-mentioned iron melting pot of the sulfur device projects a desulfurizing agent, and the system performs desulfurization treatment of the molten iron thrown into the above-mentioned iron melting pot, and is characterized in that: The system further includes a control unit that performs movement control so that the front end of the top blowing pipe reaches a position at a predetermined height from the liquid level of the iron melting pot, The control unit is provided with means for calculating the moving distance and means for driving the blowpipe, The moving distance calculating means calculates the water outlet height of the iron melting pot based on the tilt angle of the iron melting pot during the pretreatment of the desulfurization treatment, that is, the slag removal treatment and the inner diameter of the iron melting pot, and according to The calculated water outlet height calculates the moving distance of the aforementioned top blowing pipe, The blow pipe driving means drives the top blow pipe so that the front end of the top blow pipe reaches a predetermined height from the liquid level of the iron melting pot based on the calculated moving distance. The mechanically agitated desulfurization system according to claim 1, wherein, The moving distance calculation means of the control unit is provided with a table for associating the tilt angle and the water outlet height according to the different loss degrees of the iron melting pot, and is obtained by using the table corresponding to the input loss degree. The above-mentioned water outlet height is used to calculate the moving distance of the above-mentioned top blowing pipe.

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