RU2776656C1 - Lining of the lower part of the vacuum chamber - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be applied in the vacuum processing of liquid steel. The lining of the lower part of the vacuum chamber contains a hearth, a working lining layer, a submersible inlet pipe and a drain pipe, having a working layer of the refractory lining of the inlet pipe, a working layer of the refractory lining of the drain pipe, an outer working layer of the refractory lining. In the working layer of the refractory lining of the inlet pipe, there are gas supply channels, while the thickness of the working layer of the lining in the cross section of the inlet pipe is determined by the formula, taking into account the thickness of the working layer of the inner space of the inlet pipe and the coefficient of increase in the thickness of the working layer of the refractory lining of the inner space of the inlet pipe in the range from 1.05 to 1.60.

EFFECT: invention is aimed at reducing the risk of accidents, increasing the duration of the lining, reducing the specific consumption of refractory materials and products.

4 cl, 2 dwg, 1 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to steelmaking and can be used in the vacuum treatment of liquid steel with the main purpose of steel degassing.

Known submersible pipe for the degasser, consisting of a metal structure, lined with refractory rings [1] (patent RU 96 574 U1 "Submersible pipe for the degasser", IPC C21C 7/10, publ. 10.08.2010), consisting of a metal structure, lined with refractory rings, while the lower refractory ring has an L-shaped profile in section, and the metal structure is equipped with a fixing stop.

The disadvantage of this lining is: increased labor costs, irrationally used time of technological personnel, increased costs for the consumption of refractories for lining pipes of vacuum chambers of degassers.

The closest solution to the invention is a submersible branch pipe for a circulating degasser [2] (patent RU 2 736 127 C1 “Submersible branch pipe for a circulating degasser”, IPC C21C 7/10, publ. 11/11/2020), consisting of a metal structure lined with refractory products and lined with refractory concrete, and between the inner surface of the metal structure and the outer surface of the refractory products there is a buffer layer of refractory concrete, while the refractory products are made of refractory bricks having a rectangular cross section, and the lower refractory product is made of refractory bricks having a cross section of U-shaped, while the mentioned refractory products are assembled in the form of an annular polygon, and the metal structure of the branch pipe is provided with a supporting metal product made of segments (7) fixed with gaps around the circumference to ensure the fixation of the said lower refractory product.

The disadvantage of this lining is the lack of an optimal ratio of refractory consumption per lining campaign of the lower part of the vacuum chamber of the useful volume of the internal space of the inlet pipe, as a result of which a high residual value of the working layer of the refractory lining and a low useful volume of the internal space of the inlet pipe can be observed, which leads to an increase consumption of refractory materials and products, as well as a decrease in the performance of the steelmaking shop.

Modern circulating-type degassers are equipped with a vacuum chamber that acts as a working vessel with an internal space for metal circulation and removal of gases from ever-incoming portions of metal. The vacuum chamber consists of the following elements:

- the upper part, which acts as the transfer of exhaust gases to the flue;

- the middle part, located between the upper and lower parts and providing the location of the burner during heating of the lining and annealing of slag formations on the surface of the working layer of the lining, as well as supply of alloying and slag-forming materials to the metal;

- the lower part, designed to receive the metal - its entry into the inside of the chamber and removal to the steel ladle.

The lower part of the vacuum chamber 1 (Fig. 1) consists of a hearth 2, a refractory lining of the walls of the vacuum chamber 3, an inlet pipe 4 and a drain pipe 5.

The evacuation process is carried out as follows. The liquid steel in the steel-pouring ladle, which in turn is located on the steel carrier, is delivered to a circulation-type degasser. The steel carrier is placed under the vacuum chamber in the processing position. The vacuum chamber goes down, or the steel truck with the ladle goes up, the inlet pipe 4 and the drain pipe 5 of the lower part of the vacuum chamber 1 are inserted into the metal. A number of high power pumps carry out a vacuum inside the space of the vacuum chamber, tending to an absolute vacuum - no more than 3.0 mbar. Due to the vacuum created inside the lower part of the vacuum chamber 1, the metal rushes up through the inlet pipe 4 and the drain pipe 5. The carrier gas is supplied to the inlet pipe 4 through the gas supply purge tubes of the collector system 6, passing through the working layer of the refractory lining of the inlet pipe 7. When the gas medium of the carrier gas appears inside the inlet pipe 4, its lifting force increases, as a result of which the metal lifting speed increases, the metal fills the lower part of the vacuum chamber 1 and drains through the drain pipe 5. The duration of vacuuming is determined by the need to obtain the target values of hydrogen in liquid steel after processing.

The vacuum chamber is equipped with a refractory lining, the laying of which is carried out according to a special scheme. The inlet pipe 4 and the drain pipe 5 of the lower part of the vacuum chamber 1 are also equipped with a working layer of the refractory lining of the inlet pipe 7, a working layer of the refractory lining of the drain pipe 8 and an outer working layer of the refractory lining of the pipes 9.

With constant circulation of liquid metal through the inlet pipe 4 and the drain pipe 5 during the period of vacuum processing, the working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8, the outer working layer of the refractory lining of the pipes 9 are exposed to temperature and chemical effects of metal and slag, as a result, the working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8 wears out from heat to heat. If a minimum residual value of the thickness of the working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8 occurs, the vacuum chamber is decommissioned for repair. Requires technological downtime for the dismantling of the metal structures of the pipes 10 from the metal case of the vacuum chamber 11 at the point of their docking 12, the dismantling of the lining of the working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8, the hearth 2 and the subsequent installation of these elements.

The working layer of the refractory lining of the inlet pipe 7 is operated in more aggressive conditions in comparison with the working layer of the refractory lining of the drain pipe 8 and is subject to more intense wear.

The technical result of the invention is: reducing the cost of integrated ownership of the lining of vacuum chambers of circulating metal degassing installations in order to optimize the thickness of the lining of the vacuum chamber and the internal space of the nozzles without changes or with minimal changes in the technological parameters of the process of vacuum processing of steel, and, accordingly, in increasing service life of the refractory lining.

The specified technical result by increasing the service life of the lining is achieved by optimizing the thickness of the refractory masonry of the working layer with a change in the usable volume of the internal space of the inlet pipe. This is ensured by the fact that in the lining of the lower part of the vacuum chamber 1, containing the hearth 2, the working layer of the lining 3, the submersible inlet pipe 4 and the drain pipe 5, having a working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8, the outer working layer of the refractory lining 9, and in the working layer of the refractory lining of the inlet pipe 7 there are gas supply channels 13, in which gas supply purge tubes of the collector system 6 are installed, according to the invention, the thickness of the working layer of the lining in the cross section of the inlet pipe 4 is determined by the formula:

S ₂ \u003d S ₁ × K ₁ (1),

where:

S ₁ is the thickness of the working layer of the inner space of the inlet pipe 4 (Fig. 1);

S ₂ - increased thickness of the working layer of the inner space of the inlet pipe 4 (Fig. 2);

K ₁ - coefficient of increase in the thickness of the working layer of the refractory lining of the inner space of the inlet pipe 4 in the range from 1.05 to 1.60;

and the diameter of the inner space of the inlet pipe 4 is determined by the formula:

D ₂ \u003d D ₁ - 2 × S ₁ × (K ₁ - 1) (2),

where:

D ₁ is the diameter of the inner space of the inlet pipe 4 of the vacuum chamber;

D ₂ - reduced diameter of the inner space of the inlet pipe 4 of the vacuum chamber.

In addition, the length of the gas supply purge tubes of the collector system 6 is determined by the formula:

L ₂ \u003d L ₁ × K ₂ (3),

where:

L ₁ - the length of the gas supply purge tubes of the collector system 6;

L ₂ - increased length of the gas supply purge tubes of the collector system 6;

K ₂ - coefficient of increase in the length of the gas supply purge tubes of the collector system 6 from 1.05 to 1.50.

In addition, the gas supply purge tubes of the manifold system 6 are made of heat-resistant steel, for example, chromium-nickel steel containing wt. %: C 0.05-0.50; Mn 0.10-1.50; Si 0.03-1.50; P less than 0.045; S less than 0.045; Cr 5.00-30.00; Ni 5.00-20.00; Cu - less than 0.50; Ti - 0.01-1.00; Fe is the rest.

In addition, the number of gas supply channels 13 in the working layer of the refractory lining of the inlet pipe 7 is from 2 to 50 pieces.

In the lining of the inlet pipe 4, the following differences are provided:

- increased thickness of the working layer of the inner space of the inlet pipe of the vacuum chamber 4 is determined by the formula:

S ₂ \u003d S ₁ × K ₁ (1);

- the reduced diameter of the inner space of the inlet pipe 4 is determined by the formula:

D ₂ \u003d D ₁ - 2 × S ₁ × (K ₁ - 1) (2);

- the increased length of the gas supply purge tubes of the manifold system 6 is determined by the formula:

L ₂ = L ₁ × K ₂ (3).

Thus, the working layer of the refractory lining of the inlet pipe 7 and the interior of the inlet pipe 4 have a more perfect design, which reduces the risk of accidents, increases the life of the lining, and reduces the specific consumption of refractory materials and products.

The specified increased thickness of the working layer of the refractory lining of the inlet pipe 7, the reduced diameter of the inner space of the inlet pipe 4, the increased length of the gas supply purge tubes of the manifold system 6 make it possible to increase the resistance of the lining of the inlet pipe of the vacuum chamber 4 to reduce the cost of purchasing linings.

During operation of the vacuum chamber, the working layer of the refractory lining of the inlet pipe 7 is eroded by moving metal. The operating time of the vacuum chamber depends on the thickness of the working layer of the inner space of the vacuum chamber branch pipe S ₁ , if this parameter is increased by the coefficient of increase in the thickness of the working layer of the refractory lining of the inner space of the branch pipes K ₁ , then the duration of operation of the vacuum chamber lining will increase. However, it should be taken into account that an increase in the thickness of the working layer of the refractory lining of the inner space of the nozzles 7 mirror-reduces the diameter of the inner space of the inlet pipe D ₁ , which will lead to a change in the technological process of steel vacuum processing in the vacuum chamber.

Simulation of the movement of the melt in laboratory conditions and tests on real metallurgical units have shown that with the coefficient of increase in the thickness of the working layer of the refractory lining of the inner space of the nozzles K ₁ , which is in the range of 1.05 to 1.60, the technological parameters of steel processing in a vacuum chamber make it possible to obtain high quality steel.

When the value of S ₂ less than 1.05S ₁ will lead to the absence of a technical result.

When the value of S ₂ more than 1.60S ₁ may lead to a decrease in the technological parameters of steel processing, which is unacceptable for the production of high quality steel.

To ensure the circulation of the metal, a neutral gas, for example, argon, having an ambient temperature, is supplied to the inlet pipe 4 through the gas supply purge tubes of the collector system 6. If a neutral gas, for example, argon, is allowed to come into direct contact with the working layer of the refractory lining of the inner space of the nozzles 7, the lining of which is heated to the temperature of the molten metal (more than 1530º C), there will be a thermal effect on the working layer of the refractory lining of the inner space of the nozzles 7 and, as a result, its destruction and reduction of the operating time of the vacuum chamber. The exclusion of this negative phenomenon is achieved by increasing the length of the gas supply purge tubes of the collector system 6. With an increase in the length of the gas supply purge tubes of the collector system L ₁ by the coefficient of increase in the length of the gas supply purge tubes of the collector system K ₂ , neutral gas, for example, argon, is fed directly into the moving metal, excluding negative impact on the working layer of the refractory lining of the inlet pipe 7.

When the value of L ₂ less than 1.05L ₁ will lead to the absence of a technical result.

For L₂over 1.50L_one, can result in substantial manufacturing costs for the gas supply purge tubes of the manifold system.

Production of gas-supply purge pipes of the manifold system 6 from heat-resistant steel, for example, from chromium-nickel steel, containing mass. %: C 0.05-0.50; Mn 0.10-1.50; Si 0.03-1.50; P less than 0.045; S less than 0.045; Cr 5.00-30.00; Ni 5.00-20.00; Cu - less than 0.50; Ti - 0.01-1.00; Fe - the rest is due to technical and economic feasibility in terms of the cost of alloying materials with expensive alloying additives and the cost of removing harmful impurities.

When using gas supply channels 13 in the working layer of the refractory lining of the inlet pipe 7 in an amount of less than 2 pieces, there is an insufficient effect on the transport of metal through the interior of the inlet pipe 4, as well as an increase in the speed of the local heat of the working layer of the refractory lining of the inlet pipe 7 in the gas supply channel 13.

When using gas supply channels 13 in the working layer of the refractory lining of the inlet pipe 7 in an amount of more than 50 pieces due to the lack of technical and economic feasibility, as well as due to the frequent location of the gas supply channels 13 in the working layer of the refractory lining of the inlet pipe 7, the combination of local wear zones of the working layer of the refractory lining of the inlet pipe 7 and conclusions of the vacuum chamber from operation.

The essence of the proposed lining of the steel-pouring ladle is illustrated by drawings, on which:

Fig. 1 - used scheme of lining the lower part of the vacuum chamber 1;

Fig. 2 is a diagram of the working layer of the lining of the inlet pipe of the vacuum chamber 1 according to the invention.

Description of reference position numbers:

1 lower part of the vacuum chamber;

2 hearths;

3 refractory lining of the walls of the vacuum chamber;

4 inlet pipe;

5 drain pipe;

6 gas supply purge tubes of the manifold system;

7 working layer of refractory lining of the inlet pipe;

8 working layer of refractory lining of the drain pipe;

9 outer working layer of refractory lining of pipes;

10 metal structures branch pipes;

11 metal body of the vacuum chamber;

12 docking point of the metal case of the vacuum chamber 11 and metal structures 10;

13 gas supply channel;

S ₂ - increased thickness of the working layer of the inner space of the inlet pipe 4 of the vacuum chamber;

S ₁ - the thickness of the working layer of the inner space of the inlet pipe;

K ₁ - coefficient of increase in the thickness of the working layer of the refractory lining of the inner space of the inlet pipe 4 in the range from 1.05 to 1.60;

D ₁ is the diameter of the inner space of the inlet pipe 4;

D ₂ - reduced diameter of the inner space of the inlet pipe 4;

L ₁ - the length of the gas supply purge tubes of the collector system 6;

L ₂ - increased length of the gas supply purge tubes of the collector system 6;

K ₂ - coefficient of increase in the length of the gas supply purge tubes of the collector system 6 from 1.05 to 1.50.

On FIG. 2 shows the proposed lining of the inlet pipe 4.

The lower part of the vacuum chamber 1 has a hearth 2 and a refractory lining of the walls of the vacuum chamber 3, a submersible inlet pipe 4 and a drain pipe 5, while the metal structures of the pipes 10 are connected by electric arc welding with the metal case of the vacuum chamber 11 at the docking point 12 of the metal case vacuum chamber 11 and metal structures 10. The working layer of the refractory lining of the drain pipe 8 has no changes, and the working layer of the refractory lining of the inlet pipe 7 has an increased thickness. The working layer of the refractory lining of the inlet pipe 7 has gas supply channels in which the gas supply purge tubes of the manifold system 6 are located. %: C 0.05-0.50; Mn 0.10-1.50; Si 0.03-1.50; P less than 0.045; S less than 0.045; Cr 5.00-30.00; Ni 5.00-20.00; Cu - less than 0.50; Ti - 0.01-1.00; Fe is the rest. The number of gas supply channels 13 in the working layer of the refractory lining of the inlet pipe 7 is from 2 to 50 pieces.

The lining of submersible pipes with an optimized design of the inlet pipe was tested in the conditions of the converter shop No. 1 of the EVRAZ joint-stock company of the Nizhny Tagil Iron and Steel Works. The durability of such a lining set is at least 4% higher than the durability of the prototype lining.

Thus, this technical solution meets the criterion of "novelty".

The analysis of patents and scientific and technical information did not reveal the use of new essential features used in the proposed solution. Therefore, the present invention meets the criterion of "inventive step".

Implementation of the invention

Example: the lining of the lower part of the vacuum chamber 1 is carried out in two stages. First, the submersible inlet pipe 4 and drain pipe 5 are assembled, and then the pipes are mounted directly to the vacuum chamber. Initially, the assembly of the submersible nozzles is carried out upside down. The working layer of the lining of the inlet pipe 7 and the working layer of the lining of the drain pipe 8 are installed on the mounting plate. In the gas supply channels 13 of the working layer of the refractory lining of the inlet pipe 7, gas-supply purge pipes of the manifold system 6 are introduced. 7, the working layer of the refractory lining of the drain pipe 8 and the metal structures of the pipes 10 are filled with refractory concrete, kept until the concrete is solid. Next, the formwork is installed on the mounting plate around the metal structure of the nozzles 10, the resulting gap is filled with refractory concrete, the outer working layer of the refractory lining of the nozzles 9 is formed, after which the lining is dried. At the second stage, the submersible pipes are mounted to the vacuum chamber. The metal structures of the pipes 10 are connected by electric arc welding to the metal case of the vacuum chamber 11 at the docking point 12 of the metal case of the vacuum chamber 11 and metal structures 10. Next, the gaps between the working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8 and metal casing of the vacuum chamber with rammed mass. The hearth 2 of the vacuum chamber is leveled using ramming mass. Next, the refractory lining of the walls of the vacuum chamber 3 is installed.

Sources of information

[1] Patent RU 96 574 U1 “Submersible nozzle for a vacuum cleaner”, IPC C21C 7/10, publ. 08/10/2010.

[2] Patent RU 2 736 127 C1 “Submersible branch pipe for circulation degasser”, IPC C21C 7/10, publ. 11/11/2020.

Claims (19)

1. The lining of the lower part of the vacuum chamber 1, containing the hearth 2, the working layer of the lining 3, the submersible inlet pipe 4 and the drain pipe 5, having the working layer of the refractory lining of the inlet pipe 7, the working layer of the refractory lining of the drain pipe 8, the outer working layer of the refractory lining 9, and in the working layer of the refractory lining of the inlet pipe 7 there are gas supply channels 13, in which gas supply purge tubes of the collector system 6 are installed, characterized in that the thickness of the working layer of the lining in the cross section of the inlet pipe 4 is determined by the formula

where S ₁ is the thickness of the working layer of the inner space of the inlet pipe 4 of the vacuum chamber; S ₂ - increased thickness of the working layer of the inner space of the inlet pipe 4 of the vacuum chamber; K ₁ is the coefficient of increase in the thickness of the working layer of the refractory lining of the inner space of the inlet pipe 7 in the range from 1.05 to 1.60, and the diameter of the inner space of the inlet pipe 4 is determined by the formula

where D ₁ is the diameter of the inner space of the inlet pipe 4 of the vacuum chamber; D ₂ - reduced diameter of the inner space of the inlet pipe 4 of the vacuum chamber. 2. The lining of the lower part of the vacuum chamber 1 according to claim 1, characterized in that the length of the gas supply purge tubes of the collector system 6 is determined by the formula

where L ₁ - the length of the gas supply purge tubes of the collector system 6; L ₂ - increased length of the gas supply purge tubes of the collector system 6; K ₂ - coefficient of increase in the length of the gas supply purge tubes of the collector system 6 from 1.05 to 1.50. 3. The lining of the lower part of the vacuum chamber 1 according to claim 1, characterized in that the gas supply purge tubes of the collector system 6 are made of heat-resistant chromium-nickel steel, for example, chromium-nickel steel containing, wt. %: C 0.05-0.50; Mn 0.10-1.50; Si 0.03-1.50; P less than 0.045; S less than 0.045; Cr 5.00-30.00; Ni 5.00-20.00; Cu - less than 0.50; Ti - 0.01-1.00; Fe is the rest. 4. The lining of the lower part of the vacuum chamber 1 according to claim 1, characterized in that the number of gas supply channels 13 in the working layer of the refractory lining of the inlet pipe 7 is from 2 to 50 pieces.

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