US1769447A - Open-hearth-furnace construction - Google Patents

Description

July 1, 1930. E. J. MCDONNELL 9,

OPEN HEARTH FURNACE CONS TRUC TI ON Filed May 16 1921 Patented July 1, 1930 UNITED STATES PATENT OFFICE ASSIGNMENTS, TO OPEN HEABTH COMBUSTION A CORPORATION OF DELAWARE COMPANY, OF CHICAGO, ILLINOIS,

OPEN-HEABTH-FURNACE CONSTRUCTION Application filed May 16,

This invention relates to a new and improved open hearth or similar furnace, and more particularly to a construction of the air and gas ports of such a furnace particularly adapted to so introduce the gases and air as to produce a quick-burning flame, and further so constructed as to maintain the ports of constant area.

In open hearth practice, as is well known, the furnace is provided with two ends which are duplicates of each other, and with duplicate regenerating chambers. In its operation it is reversed so that each end serves alternately as an incoming and as an outgoin end. My invention is particularly applicable to furnaces of this character.

It is highly desirable to so intermingle the gas and air as to cause a quick flamethat is, a flame which begins substantially at the incomin ports. The air and gas are preheated in the regenerating chambers so that they enter through the ports at a high temperature, but this temperature of itself is not sufiiciently high to effect the proper working of the metal in the furnace. It is essential, therefore, that the combustion take place adjacent the port, or otherwise there is an area of the metal bath which is not worked, and the efliciency of the furnace is thus impaired.

A further reason for the desirability of a quick flame lies in the fact that the heated gases tend to Wear away the ports on the outgoing end of the furnace. This erosion is much increased where the flame extends to or through these ports. It has heretofore been customary in many furnaces to provide the gas ports with water-cooling means which serve to preserve these ports against distortion or wearing away, and also to maintain their effective area constant. However, the wearing away of the walls surrounding the air ports gradually enlarges these ports and thus increases the quantity of air relative to the quantity of gas. Further, this wearing away of the air ports tends to vary the direction given the air flow, so that if the ports in a new furnace properly direct the air, when the furnace is toward the end of its useful life the air 1921. Serial No. 469,860.

is improperly directed for the purpose of securing the correct flame.

In furnaces of certain types, as for example, those covered by the patent to Mc- Kune, No. 1,339,855, Open hearth furnaces, issued May 11, 1920, additional ports are provided which are normally used only for the purpose of leading off the products of combustion-that is, they are normally opened only on the outgoing end of the furnace and are closed by valves on the incoming end. In such furnaces the incoming air and gas ports. are relieved of a certain amount of the erosion caused by the heated outgoing gases, but are still subject to some wear from these gases and are of course also subject to wear from the incoming air and gas.

It is an object of the present invention to provide a new and improved port for open hearth furnaces, and air and gas passages related to such ports'so designed as to afford a proper mixture of the air and gas and thus give a quick flame which burns adjacent the incoming end of the furnace.

It is a further object to provide means to protect and maintain the area of both the air and gas ports.

It is also an object to provide an association of such a port and an auxiliary port adapted for the discharge of the products of combustion.

It is an additional object to provide means for controlling the eflective area of the discharge port and for permitting the use of such a port as an air inlet port if desired.

Other and further objects will appear as the description proceeds.

Broadly, my invention comprises one or more gas ports, the air uptakes being brought adjacent those ports and openings being provided in the gas port walls so that air may pass from the uptakes through the gas port and be mingled therein with the gas.

I have illustrated certain preferred embodiments of my invention in the accompanying drawings, in which- Figure 1 is a vertical section of a port 2 meager end of an open hearth furnace constructed pass through the openings 20, the valve 15 according to my invention:

Figure 2 is a face view o; the construc! ion of Figure 1;

Figure 3 is a fragmentary view in Yer! ical section illustrating a modified form of the device; and

Figure 4 isa fragmentary face view of the device of Figure 3.

Referring to the drawings, the air uptake 7 indicated in broken lines in Figure 1 leads from the slag pocket 8 to the transverse air space 9 in the upper part of the end of the furnace. In front of the s )ace 9 are located the ports 10 to which lead the gas uptakes 11, these gas uptakes being connected to the gas slag pocket 12. Three ports 10 are shown, but obviously they may be more or less in number. The ports 10 are directed toward the melting chamber 13 of the furnace. A laterally extending port 14 is provided above the gas ports 10, this port being controlled by a water-cooled valve or damper 15. The valve member 15 is operated in a water cooled seat or guideway 16 by means of a stem 17. The ports 10 are provided with the water cooled chamber 18 which surrounds them and which is provided with an inwardly extending portion 19 serving to define their area at their forward point.

Openings 20 are provided extending through the rear walls of the ports 10 and connecting the interior of the ports with the air space 9. These openings 20 are surrounded by a portion 21 of the water-cooled member 18 and this member serves to define and maintain the effective area of the openings. The opening 20 is similar in shape to the gas port and, as shown, is located centrally thereof.

In Figures 3 and 4 I have shown a structure similar to that of Figures 1 and 2, with the exception that the air opening 20 is horseshoe-shaped and conforms substantially to the contour of the gas port, being located in substantial ali nment with the upper and lateral walls of that port.

In the use of my furnace port construction as shown herein, when the ports are upon the incoming ends of the furnace, the valve or damper 15 is normally in the lower p0si tion. The heated gas coming up through the uptake 11 passes through the port 10 and is discharged toward the furnace melting chamber 13. The preheated air comes up through the uptake 7 to the air chamber 9 and passes through the ports 20 into the gas ports. In the gas port the air and gas streams mingle and partial combustion may take place. The combustion continues immediately from the discharge opening of the port and a quick flame is thus afforded. Should it be desired to blanket the roof of the furnace with a layer of air, or for any purpose to admit more air than may readily may be partially or wholly opened and air pmmitl'cd to enter through the passage 14.

In the form of port 20 shown in Figures '1 and 2, the air is directed centrally of the gas stream and in the form of a stream substantially the same shape as the port.

In the form of air opening 20 shown in Figures 3 and 4, the air is directed into the gas port in such manner as to enclose the gas stream upon its upper surface and upon its lateral faces. The gas is thus more or less blanketed or enclosed by a stream of air. Air is not provided upon the lower face of the gas stream, since the gas is lighter than air and tends to rise through the air.

Upon the outgoing end of the furnace, the valve or damper 15 is normally fully raised so that the wide passage 14 serves to take care of the products of combustion. A certain amount of these products of course passes through the ports 10 and through the uptake 11 to the gas slag pocket 12 and thus to the gas regenerating chambers. The water-cooling member 18 with its portions 19 and 21 serves to effectively maintain the area of both the air opening and the opening from the gas port to the furnace chamber. The mixture and direction of the incoming air and gas stream are thus maintained constant throughout the life of the furnace.

It will be observed that while the ports 10 have been referred to as gas ports, they are in fact combined air and gas ports and serve as mixing chambers for the air and gas streams, so that combustion begins either within these ports or chambers or directly at their discharge openings. A quick-burning, effective flame is thus given.

I claim:

1. In an open hearth furnace, a gas port, an air uptake adjacent said gas port, and an opening through the wall between said uptake and gas port whereby air may pass into said port, said opening being in the rear Wall of the gas port.

2. In an open hearth furnace, a gas port, an air uptake adjacent said gas port, and an openin through the wall between said uptake and gas port whereby air ma pass into said port, said opening being in the rear wall of the gas port and aligned with the discharge opening of said port.

3. In an open hearth furnace, a gas port, an air uptake adjacent said gas port, and an o ening through the wall between said upta e and gas. port whereby air may pass into said port, said opening being horseshoe shaped.

4. In an open hearth furnace, a gas port, an air uptake adjacent said gas port, and an opening through the wall between said uptake and gas port whereby air may pass into said port, said opening being adapted to ad upper and iaterai portions g In an open hearth furnace, a gas port, an uptake adjacent said gas port, an opening through the wall between said uptake and gas port whereby air may pass into said port, and water cooling means in the wall of said air opening.

6. In an open hearth furnace, at gas port, an air uptake adjacent said gas port, an opening through the wall between said uptake and gas port whereby air may pass into said port, and water cooling means in the wall of said air opening and defining said opening whereby the area of the openin is maintained constant.

a In an open hearth furnace, a gas port, an air uptake adjacent said gas port, and an opening through the wall between said uptake and gas port whereby air may pass into said port, said opening being in the rear wall of the gas port and aligned with the discharge opening of said port, the walls of said opening being provided with water cooling means which define the minimum area of the opening and serve to maintain said area constant.

8. In an open hearth furnace, a gasport, an air port above said gas port, and substantially vertically extending closure means in said air port and adapted to vary the effective opening thereof.

9. In an open hearth furnace, a gas port,

an air port above said gas port, and substantially vertically operating closure means in said air port and adapted to vary the effective opening thereof, said closure means being located in that portion of the air port extending above the gas port.

10. A furnace comprising a hearth, a gas and air passage terminating in a port in the end wall of the furnace, a gas chamber in communication with the gas and air passage, an air chamber, and a hollow cooling tank interposed between said chambers, said tank being provided with a Venturi passage ada ted tov afford communication between sai chambers and accelerate the velocity of air passing to the gas chamber.

Signed at Pittsburgh, Pennsylvania, this ninth day of May, 1921.

EDIVABD J. MCDONNELL.

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