RU2572902C2 - Method of drying and heating of carbon containing lining of steel-pouring ladles - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metal pouring. Drying and heating of the carbon containing lining of steel-pouring ladles are performed by electric radiation heaters in two stages. At the first stage the lining is heated to 600^oC, and heating is performed in a low-oxidating atmosphere achieved by air supply in the ladle space through the tuyere. The air flow rate is calculated by formula Q_air = k·M_k/τ_drying, m³/h, where k is the empirical coefficient considering the air volume for the oxidation of organic compounds, equal to 47.6, M_k is the ladle capacity, t, τ_drying is drying duration, h. At the second stage the lining is heated from 600°C to 1200-1400°C in an inert gas supplied to the ladle with the flow rate of (0.5-0.6)·M_k (m³/h).

EFFECT: increased strength of the carbon containing lining, and electric radiation heaters.

1 dwg

Description

The invention relates to methods for drying and heating, as well as maintaining, in a heated state, the lining of steel pouring ladles used in the smelting department for transporting and casting metal.

Steel-casting ladles are heated at the drying and high-temperature heating stand. The purpose of these stands is the drying of a new lining to remove physically and chemically bound water from it and hardening, as well as heating the lining to operating temperatures.

There is a method of drying and heating the lining of a bucket using a gas burner (RF patent No. 2199844, priority from 10.24.1997, mounted in a lid tightly closing the bucket during heating, and the removal of combustion products is carried out through a gas exhaust device. In this case, heating is carried out at excess pressure The combustion products inside the bucket by reducing the cross-sectional area of the exhaust device The disadvantages of this method are the low heating efficiency due to the fact that most of the energy from burning fuel is carried away with flue gases, mainly with nitrogen, for this reason, the maximum heating temperature is not more than 1100-1200 ° C.

A known method of drying and heating ladles using porous burners of the Russian Federation patent No. 2433886, convention priority of 05/16/2006 and 05/11/2007). When using such burners, a significant part of the energy of the combustion products is converted into radiant energy, which increases the thermal efficiency of the process and reduces the flow of heat carrier. The disadvantage of this method is the oxidizing atmosphere of the combustion products of the coolant, which negatively affects the carbon-containing refractories during drying and heating.

There is a method of drying and heating the lining of ladles, carried out by electric heaters (I. M. Bershitsky, A. V. Tararyshkin "Energy-saving and environmentally friendly installations for electric drying and heating of the lining of ladles", Steel magazine No. 2, M., " Intermet Engineering ", 2010, pp. 24-25), selected as a prototype. The method is implemented on a heating stand, which is a supporting structure on which a lined lid is mounted, in which 10 to 20 silicon carbide heaters are mounted. The heat transfer from the heaters to the lining is carried out mainly by radiation, which increases the efficiency of the heating process compared to gas heating, allowing the lining to be heated to 1400 ° C. The disadvantage of this method is the inability to control the redox potential of the atmosphere in the bucket during drying and heating of the lining. It is known that during drying of carbon-containing linings, coking of organic binders that are part of refractories occurs. The coking process is associated with the release of a large number of gaseous organic compounds. This leads to the deposition of carbon in the form of soot on heaters and wiring, which, in turn, causes a change in the conductivity of the heaters, local overheating, and ultimately the fusion and breakdown of the heaters. In addition, when a carbon-containing lining is heated above 500-600 ° C in an oxidizing atmosphere, carbon burns out from surface refractories, which leads to their loosening and a sharp decrease in wear resistance.

An object of the invention is to develop a technological regime for drying and heating a carbon-containing lining with electric radiation heaters.

The technical result consists in increasing the durability of the carbon-containing lining and electric radiation heaters.

The technical result is achieved due to the fact that in the method of drying and heating the carbon-containing lining of steel pouring ladles, including heating the carbon-containing lining by means of electric radiation heaters, the heating is carried out in two stages, while the first of them feeds air into the ladle to create a slightly oxidizing atmosphere, whose consumption is calculated by the formula

Q _air = k · M _k / τ _drying , m ³ / h, where

k is an empirical coefficient that takes into account the amount of air for the oxidation of organic compounds;

M _K - bucket capacity, t;

_drying τ - drying time, h,

and in the second stage, the carbon-containing lining is heated with the simultaneous supply of inert gas to the bucket with a flow rate of (0.5 ÷ 0.6) · M _k , m ³ / h.

The method is as follows. At the first stage, by electric radiation heaters in a slightly oxidizing atmosphere, achieved by feeding air into the bucket space through a tuyere, the flow rate of which is calculated by the formula Q _air = k · M _k / τ _drying , m ³ / h,

where k = 47.6, heat the lining to 600 ° C and maintain at this temperature for 4 hours. The deposited carbon is oxidized by atmospheric oxygen.

In the second stage, the lining is heated from 600 ° C to 1200 ÷ 4400 ° C in a neutral atmosphere, achieved by introducing inert gas into the bucket with a flow rate of (0.5 ÷ 0.6) · M _to (m ³ / h) through a lance or porous cork to reduce oxygen concentration and prevent carbon burnout from the refractory. With a lower consumption of argon, carbon burnout does not stop. An increase in argon consumption will lead to its additional costs without a noticeable decrease in the rate of carbon oxidation.

The invention is illustrated in FIG. 1, which shows the temperature regime for drying and heating the carbon-containing lining of steel pouring ladles.

When drying and heating a periclase-carbon lining (type MC95 / 10 according to ISO 10081-3) of a bucket with a capacity of 20 tons, the flow rate of the supplied air was determined by the formula. It amounted to ~ 250 m ³ / h, and the argon flow rate was 12 m ³ / h. Air and argon were supplied through a lance mounted in a lid with heaters. The durability of the lining of the bucket amounted to 62 heats. For comparison, the average durability of the lining of ladles, the preparation of which was carried out according to the prototype method, is 48 heats. Thus, the application of the new method allows to increase the durability of the lining by 15-20% compared with known methods, as well as reduce the duration of the preparation of a new bucket.

Claims (1)

A method of drying and heating a carbon-containing lining of steel pouring ladles, including heating a carbon-containing lining by means of electric radiation heaters, characterized in that the heating is carried out in two stages, the first of which is fed into the ladle to create a slightly oxidizing atmosphere, the flow rate of which is calculated by the formula :
Q _air = k · M _k / τ _drying , m ³ / h,
where k is an empirical coefficient that takes into account the amount of air for the oxidation of organic compounds, amounting to 47.6;
M _to - bucket capacity, t;
_drying τ - drying time, h,
and the lining is heated to 600 ^° C, and in the second stage, the carbon-containing lining is heated while inert gas is fed into the bucket with a flow rate of (0.5-0.6) · M _k , m ³ / h.

Images