US3345054A - Steel melting and more particularly gas fired regenerative furnaces - Google Patents

Description

Oct. 3, 1967 s. M. ANDONJEV ETAL STEEL MELTING AND MORE PARTICULARLY GAS 1 FIRED REGENERATIVE FURNACES Filed July 18, 1965 5 Sheets-Sheet l Oct. 3, 1967 s. M. ANDONJEV- ET AL v STEEL MELTING AND MORE PARTICULARLY GAS FIRED REGEHERATIVE FURNACES 3 Sheets-Sheet 2 Filed July 18, 1963 1967 s. M. ANDONJEV ETAL 3,345,054

STEEL MELTING AND MORE PARTICULARLY GAS FIRED REGENERATIVE FURNACES 5 Sheets-Sheet 5 Filed July 18, 1965 United States Patent Ofiice 3,345,054 Patented Oct. 3, 1967 3,345,054 STEEL MELTING AND MORE PARTICULARLY GAS FIRED REGENERATIVE FURNACES Sergei Mikhailovich Andonjev, Kharkov, Petr Gerasimovich Glazkov, Donetsk, Vladimir Alexandrovieh Kuchiu, Kharkov, Konstantin Ivanovich Makarov, Moscow, Nickolai Ivanovich Pevny and Alexandr Markovich Pochtman, Kharkov, Pavel Alexandrovich Tesner, Moscow, and Oleg Vladimirovich Filipjev, Kharkov, U.S.S.R., assignors to Gosudarstvenny Nauchno-Issledovatelsky i Proektny Institute Metallurgicheskoi Promyshlennosti Filed July 18, 1963, Ser. No. 295,886 8 Claims. (Cl. 26633) The present invention relates to the art of steel melting and, more particularly, to gas fired regenerative furnaces.

More specifically the invention relates to open-hearth furnaces fired with cold high calorific gas, such as natural or coke gas or mixture thereof.

The invention can be implemented in any industrial branch requiring a luminous flame of natural gas Without introducing liquid fuel therein.

The known regenerative furnaces fired with natural gas with a highly luminous flame at each heated side contain a firing throat, air and gas regenerators, conduits for feeding hot gases and air from the regenerators to the firing throat, a burner in each firing throat, a chamber positioned within the furnace for a preliminary cracking of natural gas thereby obtaining carbon particles, and means for feeding gas and oxidizer into the chamber.

The chambers in the known furnaces are designed for the cracking process of natural gas in order to obtain carbon particles and the yield of carbon particles is inadequate as well as the velocity of the gas carrying the carbon particles from the chamber being low and insufiicient to create the high gas velocities necessary in the open-hearth furnaces and inadequate to direct the flame torch to the surface of the steel to be melted. In addition, there is an inadequate or no control over the quantity and size of the carbon particles.

The chambers in such furnaces for a preliminary cracking of natural gas are arranged inside the furnace, thus making the furnace design and repair rather complex together with increased costs for production and operation.

An object of the present invention is to create a flame of natural gas with a high and controlled luminosity with the flame having a high velocity and being directed at the surface of the steel to be melted.

Another object of the invention is to increase the useful space of the hearth in the known operating furnaces and augment the output thereof without any change in the overall furnace dimensions, by the elimination of the channels and feeding of the gas from the gas regenerators to the firing throat, since the regenerative gas-heating process is eliminated. Still another object of the present invention is to use the heat given up by fuel gases in the air regenerator and the pressure of the natural gas which is introduced for the heating of the furnace.

To accomplish the above and other objects, the regenerative furnace is fired by natural gas with high and controlled luminosity and comprises firing throats located at each fired side, air regenerators, conduits for supplying hot air from the regenerators to the firing throat, burner means arranged in the firing throat, a chamber for a partial combustion of a part of the natural gas and obtaining carbon particles with the chamber being connected to the firing throat and means for feeding gas and oxidizer into the chamber.

Such feeding means are in the form of a branch pipe for the axial feeding of gas and the tangential feeding of air, or in the form of a device for mixing gas and oxygen positioned at the chamber inlet. The chamber can be positioned both in the firing throat and outside of the furnace and located either coaxially with or at an angle to the axis of the burner.

The use of the heat given up by the fuel gases in the air regenerator can be effected by means of connecting the conduits for the hot air with the branch-pipe for the tangential feeding of air into the chamber through a pipe having a jet orifice for injecting the hot air from the regenerator by compressed air supplied from any suitable source.

The implementation of the natural gas for feeding coke gas, if the latter is used for furnace heating and is fed at low pressure, is possible by means of a jet fixed on the branch pipe feeding the coke gas to the burner means and the jet is connected with natural gas fed at high pressure.

Further objects and advantages will become readily apparent to persons skilled in the art from the following detailed specification and accompanying drawings, in which drawings:

FIG. 1 is a diagrammatic view partly in elevation and partly in cross section of a heated side of an open-hearth furnace and the chamber for the partial combustion natural gas arranged according to the present invention vertically and outside of the furnace;

FIG. 2 is a fragmentary view partly in elevation and partly in cross section of the firing throat and the chamber for the partial combustion of natural gas arranged outside the furnace co-axially with the burner means.

FIG. 3 is a view partly in elevation and partly in cross section of the chamber for the partial combustion of the natural gas and the burner means connected co-axiall with the chamber.

FIG. 4 is a vertical sectional view of the firing throat and the co-axially arranged chamber for the partial combustion of natural gas and burner means positioned in the throat; and

FIG. 5 is a fragmentary view partly in elevation and partly in cross section of the firing throat and the burner means positioned therein connected with the chamber for the partial combustion of the natural gas when it is placed at an angle to the axis of the burner outside the furnace.

As disclosed in FIG. 1, a regenerative furnace 1 adapted to be fired by natural gas with high and controlled luminosity at each fired side thereof is provided with a firing throat 2, air regenerator 3, a duct 4 for supplying hot air from the regenerator 3 to the firing throat 2, burner means 5 arranged in the throat 2, a chamber 6 for the partial combustion of the natural gas and for obtaining free carbon. The chamber 6 is located exteriorly of the furnace and is connected with the burner means 5. In FIG. 1, it will be seen that the chamber 6 is positioned at an angle to the burner 5.

A casing 8 of the chamber 6 is provided with an end lid or cap 7 carrying a branch-pipe 9 serving for the axial feeding of a natural gas into the chamber 6. The side wall of the casing 8 supports a branch-pipe 10 for the tangential supply of air for the chamber 6.

A conduit 11 connects the duct 4 with the branch-pipe 10 and is provided with a jet orifice 12 which is supplied With compressed air in the direction shown by arrowhead R from a compressor (not shown). The compressed air serves for injecting hot air from the duct 4 and for feeding the resulting hot air mixture under pressure through the branch-pipe 10 into the chamber 6, with the pressure exceeding atmospheric pressure.

In addition to the means above described, air can be introduced into the chamber 6 in a cold condition or enriched by oxygen by means known to persons skilled in the art. The hot gaseous products of partial combustion are fed from the chamber 6 through the burner means into the furnace *1 and contain mainly carbon particles serving for the flame luminosity. The products of partial combustion may contain none or a negligible amount of acetylene.

By controlling the volume of the air which is introduced through the branch-pipe 10 into the chamber 6, it it is possible to vary the quantity and size of the carbon particles resulting from a partial combustion of a part of the natural gas supplied for the heating of the furnace and the same means functions to control the flame luminosity.

By controlling the pressure of the gas and air introduced into the chamber 6 for the partial combustion process, the velocity of the products of partial combustion fed into the furnace 1 through the burner means 5 having corresponding cross-section dimensions can be influenced. In this burner means, the hot products of the partial combustion of the natural gas are mixed with the rest of the natural gas and coke gas as well if such latter gas is applied for the heating of the furnace.

As shown in FIG. 2, a branch-pipe 13 supplies coke gas from a conduit 14 to the burner means 5 and is provided with a jet 15 supplied with a natural gas under high pressure through a branch-pipe 16 from the main pipeline (not shown). This gas functions for the highspeed injection of the coke gas into the furnace 1 through the burner means 5.

Referring to FIG. 3, it can be seen that the burner 5 is a unit provided with a water jacket 17 equipped with a water-feed pipe 18 and a water-discharge pipe 19. The water jacket 17 is lined with refractory material, such as brick 20, which provides a channel 21 for conducting a mixture of gases consisting of the products of partial combustion of a part of the natural gas, the remaining part of natural gas and coke gas, in case such latter gas is used into the furnace 1. The design of the burner 5 is such as to supply oxygen or steam through ducts 25 which can be positioned outside of the burner casing as shown in FIG. 5 and the said oxygen and water serve to intensify the melting process.

As illustrated in FIG. 4, when the chamber 6 and burner 5 are positioned in the firing throat 2 of the furnace 1, a common water-cooled jacket 26 is employed. The jacket includes a pipe 27 and a water-discharge pipe 28, as well as ducts 29 which introduce oxygen or water steam into the furnace 1 for intensifying the steel melting process. FIG. 3 illustrates a variant of the chamber 6 in which oxygen is used as an oxidizer for the partiazl combustion process with the oxygen being initially mixed with the natural gas in unit 22. The oxygen is fed into the unit 22 through a branch-pipe 23, while the natural gas is fed through a branch-pipe 24.

When oxygen is used as an oxidizer, there are created in the chamber 6, hot products of the partial combustion of the natural gas containing carbon particles and, mainly, acetylene, which is easily decomposed and creates carbon particles in the flame torch of the furnace 1.

As shown in FIG. 3, the casing 8 of the chamber 6 .is equipped with a refractory brick lining 30. To maintain the temperature of the dining at a level ensuring a reliable ignition of the gas and oxidizer mixture in the chamber 6 after the fire in the furnace 1 is directed to another size, a small amount of the natural gas and oxidizer is continuously introduced into the chamber 6. For this purpose, natural gas is fed by a branch-pipe 31 and compressed air by branch-pipe 32. Aperture 33 in the lining of the chamber 6 serves for collecting analysis samples of the products of partial combustion and visual control of the combustion process within the chamber 6 is effected through an inspection hole 34. In order to provide a connection with the burner means 5, the lining 30 of chamber 6 is in the form of a cone 3S and thermocouple 36 measures the temperature.

Referring to FIG. 5, it will be seen that the chamber 6 is positioned outside of the furnace at an angle to the axis of burner 5 and the chamber 6 is connected with the burner 5 by means of an elbow jacket 37 provided with an inner refractory brick lining (not shown).

The jacket 37 is equipped with a branch-pipe 38 having a removable lid or cover 39 and the pipe 38 serves for cleaning the channel 21 of the burner means 5 from solid litter particles which may collect from the furnace 1 as well as for collecting samples of the partial combustion products from the chamber 6'. Moreover, the pipe 38 can be used for the installation of an inspection hole.

When the furnace is in operation, the natural gas and oxidizer are introduced into the chamber 6 in which the products of partial combustion having a temperature about 1200 C. and containing acetylene and/ or carbon particles depending on whether oxygen or air has been used as an oxidizer are obtained and the oxidizer is supplied in an amount insuflicient for the complete combustion of the mixture. From the chamber 6 the products of partial combustion are directed to the burner means 5 in which they are mixed with the remaining part of the natural and coke gas, if the latter gas is used.

The gas and oxidizer pressure at the inlet of the chamber 6 and the pressure of the natural and coke gases at the inlet of the burner means 5 exceed the mean atmospheric pressure and the pressure is so selected as to overcome the resistance against the gas stream on its travel to the furnace 1 and create a fuel gas speed not less than 50 in. per second at the burner outlet.

The quantity of carbon particles supplied for the flame luminosity is easily controlled by changing the volume of the oxidizer introduced into the chamber 6 for the partial combustion process. The flame luminosity can be regulated by changing the volume of the gas as well but the control with the aid of changing the amount of an oxidizer is preferable. Additional checking of the partial combustion process in the chamber 6 is by measurements taken by the thermocouple 36.

Prior to the starting of the furnace, the lining of the chamber 6 is warmed by a complete burning therein of some natural gas and a corresponding amount of air. The gas and air are fed even when the furnace firing is transferred to another size and the gas and oxidizer feed for the partial combustion process at such side is arrested. When the chamber resumes its operation at this side, the burning of the small quantity of gas therein results in a reliable ignition of the gas supplied for a partial combustion.

The invention is not to be confined to any strict conformity to the showings in the drawings but changes or modifications may be made therein so long as such changes or modifications mark no material departure from the spirit and scope of the appended claims.

What we claim is:

1. A regenerative furnace fired by a natural gas with a high and luminous flame, comprising a firing throat, air regenerators, conduits for feeding hot air from the regenerators to the firing throat, burner means arranged in the firing throat, means constituting a chamber for a partial combustion of a part of the natural gas accompanied by creating carbon particles, means connecting the chamber with the burner means, and means for feeding gas and oxidizer into the chamber.

2. The regenerative furnace as claimed in claim 1 in which said chamber is positioned coaxially with respect to the burner means.

3. A regenerative furnace as claimed in claim 1 in which said chamber is positioned at an angle with respect to the burner means.

4. A regenerative furnace fired by a natural gas with a high and regulated flame luminosity, comprising a firing throat, air regenerators, conduits for feeding hot air from the regenerators to the firing throat, burner means arranged in the firing throat, means constituting a chamber for a partial combustion of a part of the natural gas accompanied by creating carbon particles, means connecting the chamber with the burner means, a branch-pipe for axial introduction of a natural gas located at one end of the chamber and a branch-pipe for tangential air supply to the chamber located on the side wall of the chamher.

5. A regenerative furnace fired by a natural gas with a high and regulated flame luminosity comprising a firing throat, air regenerators, conduits for feeding hot air from the regenerators to the firing throat, a burner means arranged in the firing throat, means constituting a chamber for a partial combustion of a part of the natural gas accompanied by creating acetylene and carbon particles, means connecting the chamber With the burner means, and a device for mixing the natural gas fed into the cham- -ber with oxygen.

6. A regenerative furnace fired by a natural gas With a high and regulated flame luminosity, comprising a firing throat, air regenerators, conduits for feeding hot air from the regenerators to the firing throat, burner means arranged in the firing throat, means constituting a chamber for a partial combustion of a part of the natural gas accompanied by creating carbon particles positioned outside the furnace, means connecting the chamber with the burner means, a branch-pipe for tangential air supply to the chamber located on the side Wall of the chamber.

7. A regenerative furnace as claimed in claim 6 including a conduit for feeding hot air to the firing throat, a

pipe connecting the conduit with the branch-pipe for the tangential air supply, a jet for the pipe, and means for feeding air under pressure to the pipe.

8. A regenerative furnace fired by a mixture of natural and coke gas, comprising a firing throat, air regenerators, conduits for feeding hot air from the regene-rators to the firing throat, means constituting a chamber for a partial combustion of a part of the natural gas positioned outside the furnace, means for feeding gas and oxidizer into the chamber, means for feeding the products of partial combustion from the chamber to the burner means, a branch-pipe for supplying coke gas to the burner means, and a jet in the branch-pipe for feeding natural gas at pressure to the burner means.

References Cited UNITED STATES PATENTS 1,933,571 11/1933 Trinks 26315 2,056,531 10/1936 Morton 26315 2,287,785 6/1942 Dean 263-15 2,298,842 10/1942 Richardson 26315 JOHN F. CAMPBELL, Primary Examiner.

R. F. DROPKIN, P. M. COHEN,

Assistant Examiners.

Claims (1)

1. A REGENERATIVE FURNACE FIRED BY A NATURAL GAS WITH A HIGH AND LUMINOUS FLAME, COMPRISING A FIRING THROAT, AIR REGENERATORS, CONDUITS FOR FEEDING HOT AIR FROM THE REGENERATORS TO THE FIRING THROAT, BURNER MEANS ARRANGED IN THE FIRING THROAT, MEANS CONSTITUTING A CHAMBER FOR A PARTIAL COMBUSTION OF A PART OF THE NATURAL GAS ACCOMPANIED BY CREATING CARBON PARTICLES, MEANS CONNECTING THE CHAMBER WITH THE BURNER MEANS, AND MEANS FOR FEEDING GAS AND OXIDIZER INTO THE CHAMBER.

Images