CN110747316A

CN110747316A - Automatic control lifting method for RH furnace vacuum treatment buggy ladle

Info

Publication number: CN110747316A
Application number: CN201911008479.2A
Authority: CN
Inventors: 张雷; 闫小柏; 杨伟强; 魏东; 张洪伟; 杨立丽; 牛剑伟
Original assignee: Beijing Shougang Automation Information Technology Co Ltd
Current assignee: Beijing Shougang Automation Information Technology Co Ltd
Priority date: 2019-10-22
Filing date: 2019-10-22
Publication date: 2020-02-04

Abstract

An automatic control lifting method for a RH furnace vacuum treatment ladle car belongs to the technical field of ferrous metallurgy and is suitable for RH furnace process control technology. During the RH furnace vacuum smelting period, a pressure sensor is additionally arranged outside the vacuum chamber, the ladle car is automatically controlled to lift along with the change of the vacuum chamber pressure and the amount of alloy added into molten steel, the burning of pipelines and equipment attached to a vacuum groove and the pollution of the molten steel are avoided, and the problem that the molten steel quality is influenced by RH furnace refining artificial factors is solved.

Description

Automatic control lifting method for RH furnace vacuum treatment buggy ladle

Technical Field

The invention discloses an automatic control lifting method for a RH furnace vacuum treatment ladle car, belongs to the technical field of ferrous metallurgy, and is suitable for RH furnace process control technology.

Background

RH external refining is a steel refining process. Because of the vacuum circulation degassing method, the method has the characteristic of high-efficiency refining and is widely used in metallurgical enterprises. The process mainly comprises a buggy ladle lifting system, a vacuum system, a condensing system, a feeding system and the like. Wherein the vacuum system consists of a vacuum groove, a vacuum pump and other equipment; two dip pipes, namely an ascending pipe and a descending pipe, are arranged below the vacuum tank; the vacuum chamber is called as vacuum chamber. The lifting of the buggy ladle is driven by hydraulic pressure and is controlled by a Programmable Logic Controller (PLC). During the smelting in the RH furnace, the vacuum tank is vacuumized. According to the process requirements, when the vacuum chamber pressure or the amount of alloy added into the molten steel changes, the ladle car needs to be manually lifted and lowered. When the buggy ladle rises too fast, the pipelines and equipment on the vacuum tank will be burnt out; when the buggy ladle is lowered too fast, air can enter the vacuum chamber, which destroys the vacuum environment and interrupts the vacuum circulation degassing process. Therefore, in the vacuum treatment process, the accurate control of the ladle car becomes an important technology of RH furnace refining.

Disclosure of Invention

In order to overcome the accurate control technology of the RH furnace refining buggy ladle, the invention provides an automatic control lifting method of the RH furnace vacuum treatment buggy ladle.

The method comprises the first step of determining the position of a zero clearing point during the rising period of the buggy ladle. And detecting the position value of the buggy ladle to be L in real time by utilizing a position encoder on the buggy ladle. When the lower edge of the dip pipe (based on the shortest of the ascending pipe and the descending pipe) contacts the slag surface, the position of the lower edge is determined as a zero clearing point, and the position value of the zero clearing point is set as L₀. When the buggy ladle reaches the position, the zero clearing button is clicked to enable the switching value input signal to enter the PLC and be recorded as DI_Zero. When DI_ZeroWhen L is equal to L, then L is equal to L₀，L–L₀And (5) when the value is equal to 0, the zero clearing purpose is achieved.

In the second step of the method, before the vacuum treatment is started, the initial depth of the dip pipe immersed in the ladle is determined. After the first zero clearing is successful, the distance for continuously lifting the buggy ladle is L-L₀This is also the dip tube depth value D, so D ═ L-L₀. In order to create a vacuum environment, the dip tube is completely immersed in the molten steel, but equipment on the vacuum tank cannot be burnt out. Through field exploration, the D value is continuously increased toThe position is 420 mm-440 mm, which is a proper initial position interval. This initial position is set to D_{First stage}When D is equal to D_{First stage}。

In the third step of the method, when vacuum is started, the relationship between the pressure of the vacuum chamber and the increasing value of the immersion depth of the immersion pipe is determined. Along with the continuous process of vacuumizing, the vacuum pressure is continuously reduced, the molten steel entering a vacuum chamber is continuously increased, and the immersion depth of the immersion pipe is continuously increased. A pressure sensor is arranged in the vacuum chamber, and a pressure signal enters the PLC and is marked as P. Let D_IncreaseFor increasing the immersion depth of the dip tube, as can be seen from the second step, D_Increase＝D-D_{First stage}. When the vacuum chamber pressure P is 500mbar, controlling the lifting D of the buggy ladle_Increase70mm is the most suitable position. When the vacuum chamber pressure P is 300mbar, controlling the ladle car to lift D_Increase170mm is the most suitable position. When the vacuum chamber pressure P is less than 50mbar, controlling the ladle car to lift D_Increase270mm, the most suitable position. According to the above conditions, the vacuum pressures P and D can be obtained_IncreaseThe relationship of (1) is: d_IncreaseThe coefficient A ranges from-0.4 to-0.6, and the coefficient B ranges from 290 to 300.

And fourthly, determining the relation between the adding amount of the alloy and the depth of the dip pipe immersed in the steel ladle. And a weighing sensor is arranged on the collecting hopper for charging and metering. Setting the total alloy feeding amount as W_{General assembly}. Along with the increase of the feeding amount, the liquid level height of the molten steel is also increased, and the ladle car is required to be controlled to descend in order to prevent burning out the attached equipment of the vacuum tank. Let D_ReducingFor vacuum start-up, the dip tube dip depth decreases by a value. After field exploration, the charging amount W is obtained_{General assembly}When the weight of the material exceeds X tons, the material exceeding C tons is controlled to descend Ymm according to the increase of 1 ton, and then D_ReducingAnd W_{General assembly}The relationship of (1) is: d_Reducing＝(W_{General assembly}-X) Y, wherein the value of X is in the range of 2-3 and the value of Y is in the range of 12-16.

And fifthly, determining the descending height of the buggy ladle after the vacuum treatment is finished. And breaking vacuum after the vacuum is finished. Because the pressure P of the vacuum chamber is suddenly increased, the molten steel in the vacuum chamber can quickly fall back into the steel ladle, so that the height of the molten steel in the steel ladle is suddenly increased to preventThe equipment on the vacuum tank is prevented from being burnt out, and the buggy ladle is required to be controlled to descend by a certain height. After groping D_ReducingZmm, Z ranges from 120mm to 180 mm.

The invention has the advantages that: reduces human intervention factors, can linearly control the lifting of the buggy ladle along with the change of the vacuum pressure and the alloy addition during the vacuum treatment,

drawings

Fig. 1 is a pressure sensor installation diagram.

Detailed Description

1. Before vacuum treatment, the position where the lower edge of the dip pipe (based on the shortest of the ascending pipe and the descending pipe) contacts the slag surface is set as a zero clearing point position L0, and the real-time detection value of the ladle car position marker is L during the ascending period of the ladle car. And clicking a zero clearing button to enable a signal of the zero clearing button to enter the PLC and recording the signal as DI zero. When DI is zero-1, then, since L is L0 and L-L0 is 0, the zero clearing purpose is completed;

2. determining the initial depth of the dip pipe immersed in the steel ladle to be 430 mm;

3. when the vacuum pressure reaches 500mbar, jacking to 500 mm; when the vacuum pressure reaches 300mbar, the vacuum pressure is raised to 600 mm; when the vacuum pressure is less than 50mbar, jacking to 700mm, and stopping;

4. as the feeding amount is increased, the ladle needs to be lowered to prevent the pipe from flooding, and when the total feeding amount is more than 2 tons, the ladle is lowered 15mm for every ton of the ladle with the feeding exceeding 2 tons.

5. After the treatment, the buggy ladle is controlled to descend by 150 mm.

Claims

1. An automatic control lifting method for a RH furnace vacuum treatment buggy ladle, which is characterized in that:

step one, additionally arranging a pressure sensor outside a vacuum chamber;

step two, determining the position of a zero clearing point during the rising period of the buggy ladle;

step three, before the vacuum treatment is started, determining the initial depth of the dip pipe immersed in the steel ladle to be 420-440 mm;

step four, when the vacuum starts, the pressure of the vacuum chamber and the dip pipe are determinedImmersion depth increase value relationship: d_IncreaseP + B, coefficient A ranging from-0.4 to-0.6, coefficient B ranging from 290 to 300, D_IncreaseThe value of the immersion depth of the dip pipe is increased, and P is the pressure of the vacuum chamber;

step five, determining the relationship between the alloy addition and the depth of the dip pipe immersed in the steel ladle: d_Reducing＝(W_{General assembly}-X) Y, wherein X ranges from 2 to 3 and Y ranges from 12 to 16; d_ReducingIs the dip tube dip depth reduction value; w_{General assembly}Is the total amount of alloy charge;

and step six, after the vacuum treatment is finished, determining that the descending height of the buggy ladle is 120-180 mm.

2. The lifting method according to claim 1, characterized in that: the position of the zero clearing point is determined by detecting the position value of the buggy ladle to be L in real time by using a position encoder on the buggy ladle; when the lower edge of the dip pipe contacts the slag surface, determining the position as a zero clearing point, and setting the position value at the zero clearing point as L₀。