US2175182A - Method for making steel - Google Patents

Description

Oct. l0, 1939. M. w. lDrrTo METHODv FOR MAKING STEEL Filed Feb. 28, 1959 3 Sheets-Sheet l M. w. DIT-ro 2,175,182

METHOD FOR MAKING STEEL Filed Feb. 28, 1939 3 Sheets-Sheet 2 ,l5-Lgf, 3,

Oct. 10, 1939. M. w. DIT-ro METHOD FOR MAKING STEEL 3 Sheets-She-et 3 Filed Feb. 28. 1939 w M ,um M

Patented oct. 1o, 1939 UNITED4 STATES PATENT OFFICE Emulsions Process Corporation,

New York,

N. Y., a corporation ofDelaware Application February 28, 1939, Serial No. 259,043

3 Claims.

This invention relates to the production of steel and more particularly to the making of steel in an open hearth furnace. The present application is directed to improvements in the 5 processes disclosed in my prior applications, lSe- Y rial Nos. 237,544 and .243,463, filed respectively on October 20, 1938 and December 1, 1938. In those applications-I have disclosed methods of making steel which reduce the period of time required to make the same from scrap iron, pigment iron or ore, or a combination of iron in the above forms. Such procedure results in the reduction of costs of producing steel, increasing the tonnage production of the furnace, and in better control of the carbon in the steel in standard practice today. In practicing the inventions disclosed in such applications, an -emulsified fuel of fuel oil and Water, and which may have oxygen as a constituent thereof, is introduced into an open hearth furnace alternately from the ends thereof, in atomized condition and at high velocity, by burners having their discharge ends positioned some Vdistance away' from the surface of the pool or mass of metal in the hearth. From'the time the jet of emulsion emerges from the end of the nozzle of either burner, until it impinges upon the molten mass in the hearth, it proceeds through a cycle of combustion, that is, there takes place a change of thev carbon and hydrocarbon into carbon monoxide and free hydrogen. During this period, while the Water-gas reaction is taking place, the total temperature of the entire mass of the fuel is raised rapidly and approximates the temperature of dissociation of the excess water into its component gases. Therefore, instead of impinging water at a relatively'low temperature against the molten mass, as before had been proposed, Water nely dispersed in fuel oil impinges against the mass at relatively high temperatures, thereby permitting a more rapid reaction of dissociation, and consequently, a speedy combination of the nascent oxygen with the molten iron.

In practicing such processes I have rfound that better results can be obtained if the emulsified fuel impinges against the top of the molten mass over a wider area than is possible when a single 50 jet only impinges the mass.

(Cl. l 'l5-45) obtain a desired turbulence over a relatively large area of the upper portion of the molten mass.

Another object is to provide a method Where-y by one or more jets of the emulsified fuel can be directed on to the molten mass from a point 5 immediately above the mass or through the roof of the hearth, which jet or jets will travel only a relatively short distance from the burner nozzle and consequently will strike the molten mass at higher velocity and With greater force.

With these and other objects in view, the invention consists in the novel process steps as will be hereinafter fully specified and particularly pointed out in the appended claims.

I have fully and clearly illustrated so much of 15 'the apparatus as is necessary for an understand ing of the invention, in the annexed drawings, in which Fig. 1 is a longitudinal vertical sectional view of a portion of an-open hearth furnace, and 20 showing my improved apparatus features incorporated therein.

Fig. 2 is a transverse vertical sectional view taken on the line2-2 of Fig. l.

Fig. 3 is a transverse vertical sectional view of 25 a detail of a Water-cooled port of the type which may be used in the roof of the furnace in connection'with any one of the emulsion. burners arranged at the roof portion of the furnace.

Fig. 4 is a top plan view of such jacket.

Fig. 5 is a longitudinal sectional view of one of the emulsion burners.

Fig. 6 is an elevation of one of the substantially conical mixing collars forming part of the burner.

Referring to the drawings, 'I designates an open hearth furnace of conventional construction having a hearth 8 to receive the mass 9 that is to be converted into steel. I0 indicates the upper surface line of the metal and II the upper 40 surface of the slag.

Suchfurnace is of the regenerator type and is provided at the ends thereof with openings I2 to receive the usual oil burners employed in such furnaces.

As disclosed in my prior applications, the burners I3 which cooperate with the ports I2, are employed to introduce either jets of fuel oil and steam or jets of water-in-fuel oil emulsion and. steam alternately through the opposite end por- 50 tions of the furnace and on to the charge contained in the hearth 8.

The burners I3 in the present case can receive either fuel oil or an emulsion of water and fuel oil through pipes I4 having .hand-controlled valves 55 I5. Steam, at high velocity, can be fed to the burners through pipes I6 having hand-controlled valves I1. Each burner has a mixing chamber I8 wherein the steam is thoroughly mixed with thefuel oil or the emulsion of water-in-fuel oil.

As may be seen from Fig. 1 the outlet of the burner I3 is spaced at one end of the hearth 8 and consequently the jet issuing from the burner has to travel a relatively great distance before it strikes the upper portion of the molten mass. Hence, its velocity is diminished to some extent and consequently it may not cause sufficient turbulence at the point of impingement as is desired. Furthermore, if only one jet is introduced from an end ofthe hearth, it will strike the molten mass only over a relatively small area, whereas it is desirable to have .the emulsion present and disturbing the mass over a relatively large area. To this end I combine with each end burner I3 one or more burners I9 positioned at the arch or roof 2U of the furnace at a point or points directly above the hearth so that such burners can direct jets of water-in-fuel oil emulsion at high velocity directly against the top of the mass in the hearth and thereby cause great turbulence over a Wide area of the upper portion of the mass.

As may be seen from Fig. 2, I propose to employ two roof burners I9.in combination with each end burner I3, and each of these burners as Well as the burner I3 may be of the type shown in Figs. 5 and 6. Each `may have a port 2| for the introduction of fuel oil or the emulsion, and such port, of course, is in communication with the pipe I4. Another port 22 axially aligned with the port 2I is arranged at the opposite side of the burner and is in communication with the pipe I6 which supplies the steam. In order to control the burners I9, the pipes III and I6 are provided adjacent to these burners with hand-control valves 23, and at points adjacent the ends of the furnace with remote control valves 24 which may be of the diaphragm type so that they can be remotely controlled by air pressure or the like.

Each of the burners I3 and I9 (Figs. 5 and 6) may be provided internally with a series of nested -collars 25 forming a central passageway through which the fuel oil or emulsion travels and in which it is mixed with the steam. It will be noted from Fig. 6 that the periphery of each of the collars 25 is provided with a series of helical threads 26 and it may be seen from Fig. 5 that such threads form spacing elements between the collars and provide helical passageways through which the steam must pass before reaching the liquid. Consequently the steam is caused to whirl before striking the liquid and this whirling action will increase the degree of mixing Within the collars and will also tend to drive the liquid rapidly out through the nozzle 21 of the burner.

A stem 28 having a portion thereof extending from a cylindrical part 29 to its tip 30, made up of a series of substantially biconical beads 3i, extends through the mixing portion of the burner, and it is provided with a threaded extensions 32 having threaded connection with a stationary portion 33 of the burner as indicated at 34. The extremity of the stem may be provided with a groove 35 to receive the end of .a screw driver employed in adjusting the stem, and a lock nut 36 may engage the outer portion of the threaded extension for locking it in any position of adjustment. A removable cap 31 normally covers the outer end of the threaded extension and the lock nut.

As may be seen from Figs. 3l and 4, the nozzle metallurgical reactions.

21 of each burner I9 extends through an elongated fiared port 38 arranged in the roof or arch 20 of the furnace and provided with a water -jacket 39. Water for cooling purposes may be passed through the jacket by means of pipes I0 and 4I. At this point it Will be noted that either one ofthe burners I9 may be turned about the axis of its ports 2I and 22 so that the jet issuing from the burner may impinge upon the mass at various places in the vicinity of the spot Where the jet from the burner I3 strikes the same.

In the Work previously disclosed in my abovementioned applications, I used the conventional equipment with which the open hearth furnaces were equipped. Where the furnace was burning mixed fuel, the usual procedure has been to have a burner on either end of the furnace which is versals. This has meant that through one steamatomizing burner, I have had to handle from one to one and one-half tons of oil per hour,

Yand the area of the charge upon which there is direct impinge from this burner arrangement is necessarily limited. This is not of particular importance, under normal procedure, where fuel oil only is used for heating, but in my process where it is necessary to obtain intimate contact over as wide an area as possible by the bath in the furnace and the Water-in-fuel oil emulsion, it is important that the emulsion be so injected that it will reach the bath without loss of high velocity thereby causing'turbulence and penetration of the slag layer by the jet, and to also have a large area of contact.

In the normal practicing of my process in accordance with the disclosures of my prior applications, the usual fuel is used in the furnace for the melting of the scrap and the melting of pig iron when it is introduced in the cold state. When the scrap and pig iron in the furnace have all been melted, there are certain periods during which it is advantageous to introduce emulsion to rapidly form the iron oxides necessary for the oxidation of the carbon and other well-known When introducing this emulsion it is advantageous that contact be secured with the slag and metal over as wide an area as is consistent with the design of the furnace, and that sufficient velocity still be present when the emulsion impinges that thisreaction will be carried on rapidly. This can be accomplished by the apparatus and procedure according to my present invention.

In practicing the process, at the start of the heat, burner I3 is used in the conventional manner with fuel oil or emulsion containing only a small percentage of water, for example, 5%. The burners I3 are alternately used in this Way and the firing is continued with the usual reversals ofthe furnace until the period during the heat when it is deemed necessary to introduce the emulsion. If oil has been used as fuel, it is then shut off and the emulsion is introduced in place of the fuel oil in the burners I3, and the remote control valves 24 are then opened by the operator to allow the emulsion and steam to be admitted into the burners I9. The effect of the high velocity by steam or the like in driving the emulsion from the three burners on to the surface of the slag causes turbulence, the impact of the emulsion on the surface of the underlying metal 9 causes the surfaces to be displaced thereby imparting motion to the metal from the dissociation of-the water of the emulsion to cause in turn the reactions Sowell-known as to need no further description.

The emulsion mixing portions of the burners I9 in the roof are protected by means of the water-cooled jackets 39 which, as before stated,

are of such design as to allow the burners to be adjusted to the angles at which they operate to best advantage. The combustion is very rapid at this portion of the furnace due to the high nozzle velocity of the emulsion mixture drawing air by injection into the furnace through the wateri cooled parts 38. Also the air coming up the conventional uptakes 42 tends to travel along underside of the roof and is mixed into the flame as a result of the high jet velocity of the emulsion. Due to the short distance that the flame has to travel, it still has a relatively heavy body when the jet impinges upon the slag covering. This is a great advantage when foaming heats are encountered and it is necessary to do what is known in open hearth parlance as knock the foam.

The percentage of water in the emulsion, pressure of the atomizing steam and other factors, can be varied so as to best suit the conditions under which the operation is being carried out. Due to the angle at which the burners are set and their general arrangement, there is no dele- -terious effect upon -the brickwork from frame proportioning pump of the type disclosed in my application Serial No. 230,480, led September 17, 1938, as it permits the proportions of fuel oil and water in the emulsion to be changed. at any time during the steel-making period. Using such a pump, I can produce a fuel oil emulsion containing, say 5% to 10% of water, and use this during the beginning of the heat to bring the charge up to the point where slags form on the surface of the pool, then the percentage of water in the emulsion can be raised to say 25% or and this emulsion can be used as a fuel and oxidizing agent in the furnace during decarbonization of the iron for the period or periods required to oxidize the carbon to any desired point to meet'the specifications of the steel. In practice, the emulsion entering the burners will be under a pressure of from approximately 300 to 400 pounds per square inch, and as the emulsion is mixed in the nozzles with steam under a pressure of about 100 pounds per square inch, the jets discharging from the burners will travel at a speed of about 20,000 feet per minute. Consequently, each jet will not only impinge against the upper surface of the bath, but will actually depress the pool at the point of impingement, and, of course, as the burners I9 are closer to the upper surface of the pool than the burners I3, the jets issuing from the burners I9 will set up an agitation or turbulence functioning to increase the speed of the reaction and to rapidly oxidize the carbon in the iron.

By Way of recapitulation, it may be stated that due to the peculiar action of the emulsion when brought in contact with the surface of the slag 5 and metal in any open hearth furnace, such action makes it desirable to create considerable agitation during the period of oxidizing carbon out of the iron. There is a layer of slag formedl on top of the metal and certain well-known metallurgical reactions are dependent upon this slag covering and the character of the slag.

As most of these reactions take place by interface contact between metal and slag, if it is desirable to increase the rate at which these reactions take place, it is necessary to create turbulence on the interface surface and the result from this turbulence is to changefthe rate of circulation on the interface. I accomplish this by bringing one or more of the burners closer to the surface of the slag and metal and then by controlling the velocity of the jet or jets to amplify the impingement or impact eifect upon the surface. Due to the high velocity, the surface of the slag is torn apart at the point of impact and the surface of the metal is depressed below its normal level and disturbed by the impact of the emulsion. This causes a high rate of surface contact between the products of the emulsion and the metal.

As pointed out in my pending applications, the oil contained within the emulsion supplies more than sufficient heat to bring about the dissociation of water into its component gases and thereby eliminates the necessity of the metal supplying heat to bring about the reaction of dissociation, that is, the temperature of the flame resulting from the combustion of the emulsion carries on the reaction of dissociation with the formation of carbon monoxiderand hydrogen and transmits heat to the surface of the metal at the same time. The oxygen and hydrogen being in contact with the slag and metallic substances at some period when critical temperatures are reached and during the period when the oxygenand hydrogen are in the nascent state, the oxidizing effect of the oxygen upon the slag or the metal is more rapid because of this nascency.

Therefore, by this method it is possible to create the iron oxides at a faster rate and by that reaction 'combined with turbulence, oxidize the carbon of the iron at a more rapid ra'te.

Theoretically, this 1reaction can take place simultaneously if it was possible by so-me form of agitation to bring the iron oxides, the slag, etc., into emulsifed form, that is, if there was a means by which metal and slag containing the required amount of iron oxide to oxidize the carbon to the required limits, the action upon the iron would be more violent and of shorter duration but such a method is impractical.

By the method herein diclosed, I approach the optimum operating conditions of intermittently or continuously disturbing the surface of the slag` and in turn the surface ofthe metal and increasing the rate of reaction as a result of thection of the emulsied fuel while in process of combustion being brought in contact with these substances.

This method eliminates the undesirable characteristic of introducing water into the metal:

1. Because it does not depreciate the heat con- It will be manifest to th ose skilled 'in t that changes may be made in the details lo? tag;

Invention, as expressed in the following claims What I claim and desire to secure by Letters Patent is:

1. In the production of st eel 1n an o n lllxrie, simultaneously injecting jetspgf {vvtlel-l o1 emulsion traveling at high VGOOW lid iii iiiOmi'Zed condition, and causing said jets to impinge ou the upper surface of a molten iron charge covered with slag in an area constituting a portion only of the entire area of said surface, and thereby causing material turbulence at the upper portion ofthe charge and in the slag, and at the same time preventing undue chilling of the charge and slag by burning fuel in proximity to said place of impingement.

2. In the production oi steel in an open hearth surfacaand thereby causing material turbulence at the upper portion of flag, simultaneously impirgriigcgajleolgati Phe ue -oil' emulsion at high velocit md 1n atom' condition on to the upper s y an lzed urface ofthe h 1n the rst-mentioned ar -c arge rargtfd laterally beyond thgaupalensufagrti silimo n Charge and thereb e bulenc y causing further turm the elat the upper portion ofthe Charge and s ag, and preventing undue ehiuing of the chargeduring such injection by burning fuei in prox1m1ty to said place of impingement.

3. In the conversion of ferric metal high in carbon into steel, simultaneouly injecting jets comprising Water and fuel oil traveling at high velocity and in atomized condition, and causing said jets to impinge on the upper surface of a molten iron charge covered with slag in an area.

constituting a portion only of the entire area of said surface, and thereby causing material turbulence at the upper portion of the charge and in the slag, and preventing undue chilling of the charge and slag during such injection by burning fuel in proximity to said place of impingement.

y MARVIN W. DI'ITO.

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