SU1560583A1 - Method of heating furnace and furnace for heating billets - Google Patents

Abstract

The invention relates to metallurgical heat engineering and can be used in furnaces with flame heating for heating metal in metallurgical and engineering plants. The aim of the invention is to reduce specific fuel consumption. To do this, in the method of heating the furnace, which includes supplying the air-fuel mixture, burning it with insufficient air, supplying secondary air to the countercurrent of the products of incomplete burning and their afterburning, the secondary air is supplied periodically with the flow rate necessary to afterburning the products of incomplete combustion, starting to supply secondary air at a minimum pressure on the hearth of the furnace (1 Pa) and ending at the maximum permissible (5-6 Pa). The stove that implements this method contains a working chamber divided into a high-temperature zone 1 with perforated roof, the openings of which are combined into a smoke outlet 3. The burners 4 are installed on the side walls of the high-temperature zone, and in the end wall 5 are burners 6. At the end methodical zone 7 is made channel 8, the output 9 of which is directed opposite to the end burners. The inlet 10 of the channel is connected to the smoke outlet of the high-temperature zone. Nozzles 11 for supplying secondary air are installed in the outlet of the channel, the cross-sectional area of the outlet 12, the channel being larger than the sum of the cross-sectional areas of the perforated roof 1.1-1.25 times. A recuperator 14 is placed in the chimney duct 13. The invention allows to intensify heat exchange in the furnace working space by creating conditions for increasing the mutual diffusion of the products of incomplete combustion and secondary air and recirculation of the unreacted part of the air-fuel mixture from the high-temperature zone to the methodical one, which reduces the specific fuel consumption for heating metal. 2 sec. f-ly, 2 ill.

Description

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the wall 5 is the burner 6. At the end of the methodical zone 7, a channel 8 is made, the output 9 of which is directed oppositely to the end burners. The inlet 10 of the channel is connected to the smoke outlet of the high-temperature zone. Nozzles 11 for supplying secondary air are installed in the outlet of the channel, and the cross-sectional area of the outlet 12 of the channel is more than the sum of the cross-sectional areas of the perforated roof 1.1-1.25 times.

The invention relates to metallurgical heat engineering and can be used in furnaces with flame heating for heating metal in metallurgical and engineering plants.

The aim of the invention is to reduce specific fuel consumption.

Figure 1 presents the proposed oven, General view, section; in fig. 2- - section aa in FIG.

The furnace contains a high-temperature zone 1 with perforated roof 2, the openings of which are combined into a smoke collector 3. On the side walls of the high-temperature zone, burners 4 are installed under the roof, and burner 6 is in the end wall 5, Outlet 9 of which is located directly under its arch and is directed opposite to the end burners. Channel 10 entrance is square with the smoke collector of the high-temperature zone. Nozzles 11 for supplying secondary air are installed in the outlet of the channel, and the cross-sectional area of the outlet 12 of the channel is more than the sum of the cross-sectional areas of the holes of the perforated roof 1.1-1.25 times. A recuperator 14 is placed in the chimney duct 13 for heating the air.

The furnace works as follows. Into the furnace, through the side-mounted burners 4, the air-fuel mixture is supplied with an air consumption ratio ensuring complete combustion of the fuel. The flow of combustion products, spreading over the surface of perforated roof 2, is heated

A recuperator 14 is placed in the chimney duct 13. The invention allows to intensify heat exchange in the furnace working space by creating conditions for increasing the mutual diffusion of products of incomplete combustion and secondary air and recirculating the unreacted part of the air-breathing mixture from the high-temperature zone to the methodical one, which reduces the specific fuel consumption for metal heating, 2 s.p, f-crystals, 2 ill.

vaet her. In the end burners 6, the fuel-air mixture is supplied with an air flow ratio of 0.4-0.6, which prevents the heated metal from oxidation and decarburization. Secondary afterburning air is introduced periodically. Begin filing

secondary air at minimum

pressure 1 Pa on the furnace with the flow rate for the period necessary for afterburning of products of incomplete combustion, located in the methodical zone 7 and

0 ejected from the high-temperature zone 1, the afterburning front is established between the end of the high-temperature zone 1 and the outlet 12 of channel 8. This eliminates

5 mixing of products of complete and incomplete combustion in the high-temperature zone 1 and excludes the emission of products of incomplete combustion into the atmosphere of the workshop through the chimney.

0 The main part of the products of incomplete combustion from the high-temperature zone 1 enters the methodical zone.

7 through the workspace. The remaining part of the products is incomplete mount5 through the perforated roof 2, the collector 3 is ejected by the nozzles 11 through the outlet 12 of the channel

8c methodical zone. Ejection is carried out by air, necessary

0 For afterburning of products of incomplete burning

The counter-flow of air with the ejected products of incomplete combustion, colliding with the stream of products of incomplete burning, which entered the methodological zone 7 from the high-temperature zone 1, contributes to an increase in the mutual diffusion of products that do not fully improve.

combustion and air, heat exchange process.

The secondary air supply is disconnected when the Maximum allowable pressure (5-6 Pa) is reached on the hearth of the furnace. At this time, the products of incomplete combustion flow from the high-temperature zone 1 to the methodological zone 7 through the working space of the furnace. When the minimum permissible pressure is reached at the hearth of the furnace (1 Pa), the counter-air is again supplied to their afterburning in the methodical zone 7. The cycle is repeated.

The beginning of the supply of secondary air at a minimum pressure (1 Pa) on the furnace hearth ensures that air is not allowed into the furnace through leaks into the linings to the working window. Stopping the supply of secondary air when the maximum permissible pressure is reached (5-6 Pa) makes it possible to eliminate the dislodging of the combustion products from the furnace and to ensure the suction of gases through the perforated arch.

The cross-sectional area of the channel outlet opening is 1.1-1.2 times larger than the sum of the cross-sectional areas of the holes in the perforated dome. This is necessary to obtain a time range during which the amount of secondary air can be supplied for afterburning in the period from minimum to maximum pressure on the hearth of the furnace. In the case when the cross-sectional area of the channel outlet opening is 1.1 times less than the sum of the cross-sectional areas of the holes in the perforated roof, when the secondary air is supplied, the pressure on the hearth of the furnace varies from minimum to maximum

practically there will be no, and therefore 45 furnaces and furnaces for heating billets

implementation of the method will be impossible.

When the ratio is greater than 1.25, the effect of the oscillatory mode is not provided.

The ratios of the cross-sectional area of the outlet of the channel and the holes of the perforated roof at the location of the floor nozzles, secondary air in the channel provide an interval from the beginning of one to the beginning of another period of secondary air supply, which allows creating conditions for pulsating combustion of incomplete combustion products, ensuring 5605836

intensified mixing, and obtain the highest burning temperature in the methodical zone with more complete fuel afterburning.

The periodic supply of secondary air allows the flow meeting boundary to change, which creates a gate-and-forward motion of products of incomplete combustion along the furnace. This contributes to an increase in the mutual diffusion of products of incomplete combustion and secondary air (improves mixing) and recirculation of the unreacted part of the air-fuel mixture from the high-temperature to the methodical zone, as a result of which heat transfer is intensified.

2o In addition, the frequency of supplying secondary air with a flow rate for the period necessary for after-burning of products of incomplete combustion, at intervals of time depending on

25 pressure on the hearth of the furnace creates conditions for the pulsating suction of products of incomplete combustion through a perforated arch, which increases its temperature, increases the radiation

30 heat transfer to metal and reduces specific fuel consumption.

The reciprocating movement of the combustion products along the furnace contributes to the intensification of the heat exchange process by increasing the mutual diffusion of products of incomplete combustion and air and recycling the unreacted part of the air-fuel mixture.

from the high-temperature zone 1 to the methodical 7, as a result of which the heat exchange is intensified.

Using the heating method

furnaces and furnaces for heating billets

allows to intensify the mixing of secondary air and products of incomplete combustion and to recirculate them from the high-temperature to the methodical zone of the furnace and increase the temperature of the arch by 20-40 ° C. Constructive execution of the furnace leads to an organized aerodynamic mode of its operation, in which the processes of mixing flows during combustion, afterburning and heating of the metal intensify heat transfer in the high-temperature zone of the furnace and reduce the specific fuel consumption.

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FIG. 2

Compiled by N.Aseeva Editor T. Lazorenko Tehred M. DidykKorrektor T. Paliy

Order 953

Circulation 510

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5

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Claims (2)

one . A method of heating a furnace, including supplying a fuel-air mixture, burning it with an air flow coefficient of less than one, supplying secondary air counter to the flow of incomplete combustion products and genius, characterized in that, in order to reduce fuel consumption, the secondary is fed periodically with a flow rate necessary for afterburning incomplete products combustion, starting to supply secondary air with a minimum • pressure on the furnace hearth of 1.0 Pa and ending when the maximum allowable pressure (5.0-6.0) Pa is reached. their doges ^I specific air Aa 2. A furnace for heating billets, containing a working chamber divided into a high-temperature zone with a perforated arch, sub-water and end burners, a smoke exhaust manifold, and a methodical zone with a channel whose output is directed counter to the end burners, the input is connected to the smoke exhaust manifold of the high-temperature zone, and ₄ also installed in the secondary air supply channel, characterized in that, in order to reduce specific fuel consumption, the ratio of the sum of the cross-sectional areas of the perforated holes water to · the cross-sectional area of the outlet channel is 1: (1.1-1.25),