SU1064104A1 - Heating forging furnace - Google Patents

Abstract

HEATING FORGER OVEN, containing a working chamber with roof and lined in Fig. 1 with a roof and a hearth, divided into a methodical zone and a high temperature zone with a perforated roof and a smoke collector, end burners, a heat exchanger and secondary air nozzles, which are different, with a secondary air burner. the purpose of increasing the efficiency of the furnace and reducing the scaling of the metal being heated, the methodical zone is provided with a vault smoke collector connected to the collector of the high temperature zone through a channel to The nozzles of the secondary air feed are placed in the air. S (L O5 4; / LAYTRU 7

Description

The invention relates to heating devices of metallurgical heat engineering and can be used in high-temperature furnaces for heating metal under pressure treatment at machine-building and metallurgical industries. A heating furnace is known, containing a working chamber with a perforated roof, a system of smoke outlets of which is connected by a collector, and burners installed on the side walls under the roof (1). Known furnace provides high quality yagreva blanks and efficient use of fuel. However, the modes of operation of heating forging furnaces have features that. impose specific requirements on their device. In the forging furnaces, the blanks are heated, which are then subjected to pressure treatment with a forging equipment. The nomenclature of the products obtained on such equipment is usually wide, and its readjustment does not require considerable time, since this only establishes a new matrix and stamp. The performance of forging equipment is expressed by the number of products processed per unit of time, and depends little on the weight of the workpiece. When switching from processing more massive products ya, the less massive number of products removed from the hearth does not change, but the mass of the metal heated per unit of time, i.e., the productivity of the furnace, decreases. This leads to an increase in the residence time of the blanks in the furnace and an increase in the scale formation. To prevent this process while reducing the productivity of a blacksmith's furnace, it is necessary to provide non-oxidative heating, i.e. create a more stable protective layer of products of incomplete combustion. Another feature of the forging furnaces is that during short breaks during readjustment or minor repairs of the forging equipment, as well as during lunch breaks, the workpieces are not removed from the furnace, i.e. an idling mode occurs. In this case, the blanks are in the furnace without movement, their residence time in the high-temperature zone increases dramatically, and scaling increases. Therefore, when idling, it is also necessary to create a more stable protective layer of products of incomplete combustion. In a known furnace with reduced performance or idling, it is necessary to burn fuel in burners with an air flow rate less than one. The resulting products of incomplete combustion protects the heated. metal from scale. But in this case, the temperature of the vault and the combustion products drops sharply, which leads to a decrease in the efficiency of the furnace and the need to increase fuel consumption. If, however, the air consumption coefficient is left to ensure complete combustion of the fuel, the scale formation will be significantly increased. At the same time, the possibility of controlling the degree of recirculation of combustion products through the arch is excluded. The closest technical solution to the present invention is a heating furnace containing a lined working chamber with vault and hearth, divided into a methodical zone and a high temperature zone with a perforated vault, the system of smoke outlets of which is combined with a collector, subfloor and end burners, recuperator for air heating and device supplying secondary air to air 2. In a known furnace, the required quality of metal heating is achieved due to the removal of a part of the products of complete combustion through the arch and feeding to Ferrous materials incomplete combustion products formed upon combustion of fuel in burners of end air flow rate factor of claim 0,4 .0,5. However, the high-temperature combustion products sucked through the roof are no longer used to heat the metal, since they do not enter the methodological zone. Thus, the amount of combustion products washing the heated metal in the methodical zone decreases, which leads to a decrease in the efficiency of the furnace. In addition, when the furnace productivity decreases, the suction of combustion products from the high-temperature zone leads to an increase in the unorganized suction of one air from the surrounding space into the working one, which increases the metal scaling and its formation at the discharge port. During idle to protect the metal from oxidation, it is necessary to keep the air flow rate less than a unit not only on j-orc burners, but also on seam burners. In this case, the In addition, in the case of chemical underburning, combustion products sucked through the roof of the combustion chamber are additionally lost and the furnace efficiency is reduced. The purpose of the invention is to increase the efficiency of the furnace and reduce the scale formation of the metal being heated. The goal is achieved by the fact that in a heating forging furnace containing a lined working chamber with roof and hearth, divided into a methodical zone and a high-temperature zone with a perforated arch and a smoke collector, underground and end burners, a heat exchanger and secondary air nozzles, the methodical zone is equipped with a vault chimney collector connected to the collector of the high-temperature zone through a channel in which 5 nozzles of the secondary air supply are placed.

FIG. 1 shows schematically the proposed furnace, a general view in section; in fig. 2 shows section A-A in FIG. I.I.

The furnace contains a high-temperature zone I with perforated roof 2, the openings of which are combined into a smoke outlet collector 3, a method zone 4 with a smoke discharge roof collector in the form of a system of openings in the roof 5. The collector 5 of roof 5 is connected to the collector 3 via channel 7 in which an ejector 8 is installed for supplying secondary air.

In the high-temperature zone I, the burners 10 are installed on the side walls 9 under the roof 2, and the burners 12 in the end wall II.

A recuperator 14 is placed in the chimney duct 13 for heating the air.

The furnace works as follows.

At a nominal capacity of 25, the air-fuel mixture is fed to the drip burners 10 in the ratio at which complete combustion of the fuel occurs. The stream of combustion products spreads over the surface of the perforated roof 2, heating it. The main part of the combustion products 30 comes from the high-temperature zone 1 to the methodical 4 directly through the furnace working space. The remaining part is ejected by the ejector 8 through the perforated roof 2 and the collector 3 into the channel 7 and further along the collector 6 through 5 the perforation of the roof 5 into the methodical zone 4. The ejection is carried out with a stream of air required for after-burning in the metodic zone 4 partial combustion products coming from high-temperature zone: 40 zone I, where they are formed as a result of supplying the end-burners 12 of the air-fuel mixture with an air flow rate equal to n 0.4-0.6, which prevents the heated metal from scaling at high temperatures raturah.45

The air supplied to the afterburning enters the methodical zone 4 heated by mixing with the ejected combustion objects from the high-temperature zone L

After the after-burning in the methodical zone, the combustion products enter the flue duct 13 and heat the air in the heat exchanger 14.

When operating the furnace at a reduced. performance and in idle mode jj and underwater burners 10 also operate with a coefficient of air flow less than one. This is caused by significant

an increase in the residence time of the heated metal in the high-temperature Zone 1. And therefore the need to create a more stable layer of protective atmosphere over the metal, which is possible when burning the fuel-air mixture with an air flow rate less than unity, both on the front 12 and on the 10 burners. In such a mode of operation of the furnace, the amount of air supplied through the ejector 8 increases, and the afterburning process begins already in the collector 6, as the channel 7 ejects products of incomplete combustion, which react with the air immediately after mixing. It also raises the temperature of the air entering through the perforated roof 5 into the methodical zone 4.

The afterburning process, starting in the collector 6 and the perforation holes of the roof 5, further heats up the roof 5, which increases the heat transfer to the metal in the methodological zone 4.

The flow of vertical air jets to afterburning in a mixture with combustion products from the high-temperature zone through the perforated roof 5 performs the additional function of an aerodynamic shutter for the horizontal flow of combustion products moving in the methodical zone 4

When the furnace performance decreases or the idle mode goes on, when the air flow rate on the burners 10 and 12 decreases and the volume of combustion products formed in the high-temperature zone I decreases, an increase in the air volume supplied to their afterburning results in an increase in the amount of vertical flow in methodical zone 4 and, thus, to an increase in the static pressure in the high temperature zone I, and a decrease in cold air leaks into it.

The heat exchanger 14 is washed by sufficiently cooled combustion products, which facilitates its operation.

This furnace design can be implemented both in arched vault furnaces and with a flat suspended vault.

Supplying the methodical zone with a roof-top smoke-collecting collector and connecting it to the collector of the arch of the high-temperature zone through the channel in which the ejector is installed allows one to eject part of the combustion products from the high-temperature zone into the methodical one through the perforated roof with air stream supplied to burn the combustion products from the high-temperature zone all formed combustion products pass directly into the methodical zone through the methodical zone. Compliance with this condition underlies the heating of the metal in the methodical zone, which increases the efficiency of the furnace. In addition, the air supplied for the after-burning of the combustion products enters the methodical zone heated by mixing with the combustion products ejected by it from the high-temperature zone, which additionally increases the efficiency of the furnace. Installing an ejector in the channel, connecting the collectors of the high temperature and methodical zones, during the furnace mode with reduced performance, begins the process of afterburning the combustion products already in the collector of the arch of the methodical zone. The afterburning process, starting in this collector and in the perforation holes of the roof of the methodical zone, provides additional heating of the roof of the methodical zone, which increases the heat and gas flow to the metal in this zone and, accordingly, the furnace efficiency. Air supply for afterburning in a mixture with combustion products from the high-temperature zone through a perforated set of the methodical zone perpendicular to the main stream of combustion products moving in the methodical zone allows automatically maintaining a positive JaaBiah in the entire high-temperature zone and therefore significantly reduce unorganized cold air suction from the surrounding space in working. This ensures the maintenance of a stable protective atmosphere in the high-temperature zone in all operating modes of the furnace, which minimizes the process of scale formation of the heated metal. The use of the proposed heating furnace will increase the efficiency by 68% on nominal capacity, reduce scale formation by 0.40, 6% of the weight of the metal being heated, and if the furnace capacity is half the nominal, increase efficiency by 10-12 / o, metal formation will decrease by 0.9-1.2% of its weight. The economic effect in comparison with the base object will be obtained due to fuel economy as a result of an increase in the efficiency of the furnace and metal saving due to a decrease in calcination when it is heated and will amount to more than 4 thousand rubles per year.

Iff

FIG. 2

Claims (1)

HEATING FORGING FURNACE, containing a lined working chamber with a roof and a hearth, divided into a methodical zone and a high-temperature zone with a perforated roof and a smoke exhaust manifold, sub-surface and end burners, a recuperator and secondary air nozzles, characterized in that, in order to increase the efficiency of the furnace reducing the scale formation of the heated metal, · the method zone is equipped with a vault smoke collector connected to the collector of the high-temperature zone through a channel in which sheny nozzle supplying secondary air. Sh) ’