SU1361176A1 - Method of heating open-hearth furnace - Google Patents

Description

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The invention relates to ferrous metallurgy, in particular to the production of steel in open-hearth furnaces, specifically to methods for heating open-hearth furnaces.

The purpose of the invention is to increase productivity and reduce energy consumption by providing a constant air temperature during smelting.

The drawing shows a graph of the coefficient of proportionality of the size of the cells of the nozzles of the generator,

The essence of the method is as follows.

When heating an open-hearth furnace, fuel is fed into its working space 4i and the air is heated in the nozzles of the regenerator.

Before entering the working space, the regenerative air is additionally heated by burning part of the fuel in its flow, regulating its flow in the course of melting relative to the nominal one.

For each open-hearth furnace, nominal fuel consumption can be set for additional heating of regenerative air. This flow rate is determined by the difference between the temperature of the air entering the working space of the furnace in order to ensure the normal maintenance of the technological process and the actual temperature of the air in the nozzles. With a nominal fuel consumption for additional heating of regenerative air during smelting, its adjustment is required due to the fact that the air heating temperature in the regenerator nozzles varies during smelting and depends mainly on the absorption of heat from the bathtub. fusions at which high heat absorption (filling and warming) from an external heat source, the torch, occurs, the air in the regenerators is heated to a lesser extent than during the periods of fusion at which liquid metal is formed in the bath, Consequently, Melting periods with intensive heat absorption of the bath require high fuel consumption for additional heating of air, and in periods with low heat absorption it may be lower than nominal. However, the temperature of the air

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nozzles may vary not only by melting periods, but also during a certain melting period. In open-hearth furnaces, the temperature of the nozzle of the regenerators can serve as a criterion for assessing the level of air heating in the regenerators, since, all other things being equal, it determines the temperature of the air heating. Thus, the nominal fuel consumption for additional heating of regenerative air in the course of smelting can be adjusted depending on the temperature difference between the set and actual nozzles.

Theoretical and experimental studies have shown that fuel consumption for additional heating of regenerative air is calculated by the formula

 + (0.5-0.75) - (t „, -t f).

where is the nominal fuel consumption, m / h; - nozzle temperature,

(given), C; t, ф - temperature of the nozzle (actual), С;

(0.5-0.75) - coefficient, m / h-deg (depends on the temperature of the nozzle and the required temperature of the air entering the furnace working space),

The described method of heating open-hearth furnaces ensures the supply of regenerative air to the working space of the furnace with an extremely high and equal temperature during the whole heat.

Example. For a 300-ton open-hearth furnace, having regenerators with a cell of nozzles of 230x230 mm in size, natural gas is supplied to the vertical channel at the moment of air passing through the burners of a special design for additional heating of the air. Calculations, refined experimental data obtained in various operating conditions of the furnace, determine the nominal consumption of natural gas, which is 300. The temperature of the air entering the working space of the furnace tends to be maintained equal in the course of melting and equal to Tem313611.

The temperature of the nozzles, based on the service conditions of the refractories, is assumed to be

nso c.

The consumption of natural gas for the additional heating of regenerative air in the course of smelting is shown in Table 1;

The proportionality coefficient varies within K (0.50 - 10 0.75) m / h-hail and depends on the thermal conditions of open-hearth furnaces having different degrees of development of the nozzle heating surface, determined by the size of the nozzle cell, and 15 can be determined , on schedule.

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shown in the drawing, where the positions 1–4 indicate the operating modes of the furnace at different blowing intensities (mode 1–8. -h, mode 26, mode 3-4, mode 4–2 m / t.h, and the type of fuel - natural gas).

Table 2 presents the performance of a 500-ton open-hearth furnace on the proposed and known methods.

The proposed method in comparison with the known provides a reduction in energy costs.

Table 1

Continuation of table 1

Specific consumption of fuel, kg / t

Specific oxygen consumption

Specific consumption of liquid iron, kg / t

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Continuation of table 1

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Editor S.Pekar

Compiled by A.Sharapova

Tehred M. Khodanich Proofreader O. Kravtsova

Order 6197/29 Circulation 550 Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, 4 Project St.

Claims (1)

METHOD FOR HEATING THE MARTEN FURNACE, including heating the air in the nozzles of the regenerator, supplying fuel to the working space of the fuel furnace for additional heating, supplying fuel and heated air to the working space of the furnace, periodically changing the direction of energy supply and removal of flue gases from the furnace and controlling the flow rate fuel for additional air heating relatively nominal, characterized in that, in order to increase the productivity of the furnace and reduce energy consumption by providing values during melting at a constant air temperature, fuel consumption V for additional heating of regenerative air along the melting process is regulated relative to the nominal depending on the difference between the set and actual temperatures of the regenerator nozzle and is determined by the following formula: V = V + (0,5-0,75) · (t MJ -. T _{and f)} with Me? Where - nominal consumption fuel, m ³ / h; m. z. - set temperature nozzles, ° C; t Lt A. - actual temperature nozzle tour, ’; (0.5-0.75) - coefficient, m ³ / h grad .. SU „„ 1361176