CA1058862A - Continuous melt furnace - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This describes a metal melting furnace consisting of a melt drum lined with refractory material. Heat is supplied by two burners, one at each end of the melt drum capable of burn-ing oil, gas or powered fuel or any combination of same. The unique burner creates a rotating flame pattern that expands to the dimension of interior of the drum and/or combustion chamber for complete contact with the molten metal and the melt drum. The melt drum is capable of partial rotative racking action first in one direction and then the other. Metal is fed through a charge port in the side wall of the drum each partial revolution and when up to temperature, molten metal may be withdrawn from pouring spouts near the top of the drum each time the drum reaches the end of its travel in either direction. The complete flame coverage of the drum and/or combustion chamber and molten metal by the rotating flame pattern plus the near constant roll-ing motion of molten metal over three-quarters of the side wall area of the melt drum ensures maximum heat utilization and rapid initial heat. A feature of the furnace is an annular exhaust flue that directs the exhaust gases passing through the side wall charging port to a vertical outlet, regardless of the rotated position of the charge port. The furnace exhaust gases are utilized to dry and preheat the incoming metal load and to gener-ate steam to protect the exhaust damper and fuel burners from erosion. The very dry steam is passed through the burners to the retort. The furnace body is water cooled. The heat picked up is absorbed in the air circuit to the fuel burners and re-cycled.

Description

1i)5886Z
BACKGROUND OF THE INVENTION
This invention relates to new and useful improvementsin continuous melt furnaces adapted to melt scrap, ingot or other forms of metal and to pour same in molten form into moulds.

There are of course relatively large and expensive units which will provide continuous pour but these are usually installed in major steel foundaries and the like.

It has long been desirable to provide a relatively small, simply constructed furnace which will allow a small foundry to operate under a continuous pour technique. Convention-ally, a charge of metal is placed within a furnace and after a given time, when the metal has reached the required temperature, the furnace is tapped and the molten metal withdrawn whereupon the entire process starts again.

This means that there is a lag between each pour in which the metal is melting so that in a working day, a relatively large amount of time is being wasted waiting for the metal to reach the pouring state.

2 0 SUMMP.B.Y OF THE INVENTION
The present invention overcomes these disadvantages by providing a furnace which can be charged continuously and which ~' - 2 - q'F

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can be poured continuously, the word "continuous" being used in this context even although metal is added and withdrawn once each cycle of a partial rotation of the furnace, namely, once every one or two minutes.

Nevertheless once the initial charge has reached melt or pouring temperature, metal may be removed so long as metal is being added thus enabling a small foundry to operate fare more efficiently than heretofore.

One aspect of the invention consists of a furnace adapted for continuous operation in the reduction of metal such as scrap, ingots and the like to molten metal ready for pouring; comprising in combination a supporting frame, a sub-stantially cylindrical drum mounted within said frame, for partial rotation in alternate directions, said drum including a charge portion and at least one combustion chamber portion, a fuel burner assembly at one end of said drum, a stationary sleeve assembly surrounding the charge portion of said drum, said drum partially rotating within said sleeve assembly, a charge port in said charge portion of said drum, a charge hop-per in said sleeve assembly communicating with said charge portwhen said charge port aligns with the base of said hopper, a partially annular exhaust duct in said sleeve assembly sur-rounding said charge portion of said drum, the interior of said drum communicating with said exhaust duct through said 5 ~d C ~c~ e ~oO ~ ~
charge port~is misa~igned from the base of said hopper, at least one molten metal pouring spout through the wall of the combustion chamber portion of said drum, and a source of power to partially rotate said drum as aforesaid.

Another aspect of the invention is to provide a device of the character herewithin described which may be readily adapted for full automatic production of molten metal.

A further aspect of the invention consists of a me-thod of reducing metal scrap, ingot and the like to moltenmetal for pouring on a continuous basis consisting of the steps of partially rotating a refractory drum first in one direction and then the other, supplying a source of heat through one end of said drum, adding metal scrap, ingot and the like to said drum through a charge opening therein, each time said charge opening reaches a metal loading position, and pouring an amount of molten metal from a pouring spout in said drum on each cycle substantially equal in weight to the weight of the scrap, ingot and the like added to said drum.

A further aspect of the invention consists of a furnace for continuous operation in the reduction of metal such as scrap, ingots and the like to molten metal ready for pouring; comprising in combination a supporting frame, a sub-stantially cylindrical drum mounted within said frame, forpartial rotation in alternate directions, said drum including a centrally located charge portion and a combustion chamber portion on each side of said charge portion, a fuel burning assembly at each end of said drum communicating with said combustion chamber portion thereof, a stationary sleeve as-~ .. ~

lOS8862 sembly surrounding the charge portion of said drum, saiddrum partially rotating within said sleeve assembly, a charge port in said charge portion of said drum, a charge hopper in said sleeve assembly communicating with said charge port when said charge port aligns with the base of said hopper, a par-tially annular exhaust duct in said sleeve assembly surround-ing said charge portion of said drum, the interior of said drum communicating with said exhaust duct through said charge port when said charge port is misaligned from the base of said hopper, at least one molten metal pouring spout through the wall of the combustion chamber portion of said drum, and a source of power to partially rotate said drum as aforesaid.

With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the preferred typical embodiment of the principles of the present invention, in which:-DESCRIPTION OF THE DR~WINGS
Figure 1 is an isometric view of the furnace.

Figure 2 is a longitudinal sectional view thereof.

Figure 3 is a Vi2W similar to Figure 2 but at rightangles therefrom.

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Figure 4 is a partially transverse section and partially schematic view of the furnace preheat oven and con-veyor showing a portion of the air circuit of the urnace.

Figure 5 is a partial transverse section showing the exhaust circuit of the furnace.

Figure 6 is a rear view of Figure 2.

Figure 7 is an enlarged fragmentary partially sec-tioned front elevation of one of the burner assemblies (shown on sheet containing Figure l).

Figure 8 is a plan view of Figure 7.

Figure 9 is a fragmentary partially sectioned view showing the junction between the major and minor sections of the main and fuel feed duct.

Figure 10 is an end view of the burner unit of Figure 8.

Figure ll is a fragmentary partially sectional view ~l ~ - 6 of the solid powdered fuel feed portion of the burner assem-bly.

Figure 12 is a longitudinally sectioned, partially schematic view of an alternate construction of the melt drum.

Figures 13, 14 and 15 show schematically, various positions of the rotating drum during the rotating cycle (shown on sheet containing Figure 1).

Figure 16 is a partially schematic, partially sec-tioned isometric view of the furnace showing the air travel and damper positions.

In the drawings like characters of reference indi-cate corresponding parts in the different figures.

DETAILED DESCRIPTION
Proceeding therefore to describe the invention in lS detail, reference character 12 illustrates a supporting base plate upon which a supporting framework 13 is supported.

The supporting framework 13 is mounted to the base plate 12 by a pair of bearings 14 (one only of which is shown), which are bolted t~ this base plate 12 (see Figs. 4 and 6).

The supporting framework 13 is pivoted transversely upon a pivot shaft 15 supported within the bearings 14 and an hydraulic jack assembly 16 extends between the base plate 12 and an adjacent end 17 of the support frame 13 so that the frame together with the furnace supported thereby, can be tilted or levelled as desired and depending upon circumstances.

The furnace collectively designated 18 consists of a melt drum lined with refractory 23 and a supporting sleeve assem-bly, fuel burners, and air supply components. The air supply components collectively designated 19 include a heat exchanger, fans, dampers and air ducts in circuit to the fuel burners as will hereinafter be described. The melt drum collectively des-ignated 20 in this embodiment includes a charge portion 21 and two combustion chamber portions 22, one upon each side of the centrally located charge portion.

A transverse framework 24 is attached to support frames 13 and mounts wheels 25 on shafts 26 between bearings 27 (see Figs. 1 and 6). The wheels 25 support the melt drum 20 on annular tracks 28 extending around the outside thereof (see Fig. 1). Two of the wheels (one shown in Fig. 6) are driven by an electric motor 28~ and reduction geared chain assembly 29 and rotate the melt drum by frictional contact with the annular flanges 28.
The melt drum does not rotate completely but travels through an arc in one direction and then returns to the uppermost position whereupon it travels in a predetermined arc in the opposite direction thus giving a partial rotative alternate action to the melt drum. The positions of the melt drum are shown schematic-ally in Fi~ures 13, 14 and 15.

The motor and drive assembly designated 29 is provided with means (not illustrated) to time the cycle of rotation that usually takes one to two minutes to complete. The means of con-trol are well known and it is therefore not deemed necessary to describe same.

This alternate rotative action is common to drum type electric arc foundry furnaces with a centre wall port that is locked closed during the melting operation. However, this degree of rotative motion through an arc totalling approximately 200 is not common to fossil fired foundry furnaces with the charge port located in the top wall of the furnace. This action is made possible by a near annular sleeve assembly hereafter to be described.

The refractory lined melt drum 20 is provided with a charge port 42, centrally located through the wall of the drum between the vertical end section or walls 118. These end walls ~-j have burner ports 117 located at the centre of the water jacketed end section 118 of the melt drum 20.

An annular sleeve assembly collectively designated 30 surrounds the charge portion 21 and a small area of the combus-tion chamber portions 22 of the melt drum 20. The melt drum partially rotates within the sleeve assembly. The sleeve assem-bly is stationary and supported upon the support frame 13 and a pair of annular flanges 31 surround each end of the sleeve and act as seals between the drum and the sleeve assembly, said flanges being secured to and rotating with the drum 20.

The sleeve assembly is in two halves divided horizon-tally at its vertical centre. The lower half 32 is supported and attached to the support frame 13. The upper half 33 is at-tached to the lower portion by a hinge 34 and can be swung open for the removal of the melt drum 20. A lift ring 35 is provided for this purpose.

A partially annular exhaust flue 36 forms part of the sleeve assembly 30 and partially surrounds the charge portion 21 of the melt drum. The exhaust flue terminates at the exhaust outlet 37 and is controlled by a steam cooled damper 38. The direction of flow of the exhaust gases is shown by arrows 36A
in Fig. 5. The sleeve also contains two annular air ducts 39 one on either side of the exhaust flue 36. The purpose of these an-nular air ducts 39 is to create a pressurised air buffer between the near annular exhaust flue 36 and the annular flanges 31 to 1058~6Z

prevent flame and exhaust gas leakage from the exhaust flue past the annular flanges 31, that would occur due to the pressure existing within the exhaust, particularly when restricted by the control damper 38. The leakage would occur by reason of a neces-sary loose clearance gap 40 between the edges of the stationaryexhaust flue 36 and the rotative melt drum 20. The source of air pressure for these air ducts 39 is subseguently described but suffice it to say that by maintaining the air pressure in the annular air ducts 39 in equilibrium with the pressure with-in the exhaust flue 36 there is no leakage through the gap 40in either direction. Alternatively by raising the air pressure above equilibrium by manipulating dampers 64 in the air duct outlets tsee Fig. 6), air is moved through the gap 40 to the exhaust flue 36, thereby converting the exhaust flue to an after burner capable of burning off excess carbon wastes, thereby creating a near pollution free exhaust. The direction of air movèment through these ducts is shown by phantom arrows 39A in Fig. 4.

A charge hopper 41 extends through the sleeve assembly 30 with the open base of this hopper terminating just above the outer surface of the melt drum so that when the melt drum is in a position shown in Fig. 4, namely at top dead centre, the hopper is in alignment with charge port 42 so that material such as scrap, ingot or the like may pass from the charge hopper 41 into the interior of the drum.

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The exhaust circuit begins with the exhaust gases from the combustion chamber passing through the charge port 42. The charge port when in line with the hopper 41 (in line to receive a metal charge) allows the flaming gases of combustion to pass through the charge hopper 41.

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When the melt drum rotates away from this position the exhaust gases are directed into and around the near annular ex-haust flue 36 to the vertical exhaust outlet 37. This exhaust outlet is controlled by the steam cooled damper 38 positioned in the exhaust outlet as hereinbefore described and the exhaust outlet 37 and the charge hopper 41 are located within the con-fines of a metal preheating oven collectively designated 43 (see Figs. 2 and 4).

This preheating oven 43 is divided horizontally for a part of its length into an upper compartment 44 acting as a bypass duct controlled by a restrictive damper 45 near the con-nection to an exhaust stack outlet 46.

A lower compartment 47 acts as a metal preheat area and also communicates with the exhaust stack outlet 46. The horizon-lS tal dividing partition is designated 43A.

A steel belted metal conveyor designated 48 extendsfrom the charge hopper 41 through the metal preheat area 47 to a loading dock (not shown). The end of the oven where the conveyor enters compartment 47, is closed by a flexible flap (not shown).

The desired temperature in the preheat area of the oven is attained by varying the volume of the hot exhaust gases pass-ing the restrictive damper 45 positioned in the bypass duct 44.

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By manipulating damper 45 the total or partial volume of the hot exhaust gases from the furnace are moved through the preheat area 47 to the stack outlet 46.

The conveyor is supported on a pair of steel channels 49 that mount on a transverse axle 50 between pillowblock bear-ings 51 tone shown, see Fig. 4). The bearings are supported on a frame assembly 52 that is secured to the floor. The conveyor can be swung away from the furnace to facilitate the removal of the melt drum and the conveyor travel is timed to deliver a pre-determined amount of metal to the furnace with each alternaterotative cycle of the melt drum. In this connection, it will be appreciated that the movement of the conveyor is intermittent and only moved when the drum is at top dead centre as shown in Fig. 4.

A refractory pad designated 53 is located in the bottom of the charge portion of the melt drum directly opposite charge port 42 in order to absorb the shock of the metal dropped through the charge port thereby protecting the main refractory lining 22 of the melt drum.

All metal surfaces of the furnace 18 and the preheat oven 43 that are subject to heat are cooled by water jackets col-lectively designated 54 to prevent distortion and erosion of the steel. The sectional water jacket 55 surrounding the melt drum is an unique arrangement in that it adds great strength to the wall structure of the melt drum. It also divides the wall sur-face of the drum into separate areas. Thus the flow of water can be adjusted to the cooling requirements of the separate areas.

The cooling system includes a water supply 56 (see Fig. 4), storage tank 57, circulating pump 58, a heat exchanger 59 and the water jackets 54 of the melt drum 18 and the preheat oven 43.

The piping circuit of the water cooling system (most of which is not shown) requires no explanation as the methods are well known.

The heat recycling air circuit begins with air being moved through flues 60 of the heat exchangers collectively desig-nated 59 and connecting to a transverse air duct 61 (shown schematically in Fig. 4) and thence to the intake of a fan 62.
This fan forces the air through an inlet manifold 63 to the two annular air ducts 39, one in each end of the manifold 63 as hereinbefore described. The air is moved through these annular hot air ducts past the restrictive outlet dampers 64 to a con-necting outlet manifold 65 at the rear of the device.

The hot air moved through the annular ducts is augmented by air supplied through inlets 67 located in the manifold 65.

10588~2 :rhese air inlets are controlled by closure dampers 66. This augmented air supply leaves manifold 65 through fan 68 and moves to the main air manifold collectively designated 69 extending towards each end of the device as shown in Figs. 3, 6 and 16.

The air stream receives additional heat from the steam generating control damper 38 through steam inlets 70.
Gas is fed to the air stream through gas inlet valve 71. The warm air, gas and steam mixture is conveyed to the fuel bur-ners collectively designated 74.

Dampers 72 and 73 control bypasses in the air circuit around fans 62 and 68. By cutting off the auxiliary air inlets by closing the closure damper 66 and opening either bypass dam-per 72 or 73 (depending on which fan would be bypassed) air can be moved through the entire length of the air circuit, i.e.
through the heat exchanger flues 60 to the fuel burners 74.

This capability is useful should either a motor or a fan fail, by allowing the furnace to operate at a lowered capa-city. It is also useful when the fuel burners are set low such as when the furnace is being preheated prior to charging. These fuel burners are situated one at each end of the drum and within the end walls 118 thereof.

The fuel burners collectively designated 74 and shown in detail in Figs. 7 and 10, consist of a housing designated 75 lOS8862 which embodies an air supply inlet 76, a venturi section 77, a powdered fuel siphon 78, an outlet 79, and a flanged annular cham-ber designated 80 having an inlet 81. An air duct 82 joins out-let 79 and inlet 81 and a damper 83 is located in this duct.
O~fices 84 and 85 are located in the inner face at the furnace end of the annular chamber 80 of the burner housing 75. The powdered fuel siphon 78 is for use when an alternative source of fuel is used such as powdered coal or the like.

A flanged multiple threaded female bushing 86 is mounted through the outer end of the housing and supports an interior unit component collectively designated 87 centrally within the housing 75.

This interior unit component consists of a hollow shaft 88 with a raised multiple thread 89 near the outer end thereof.
A control lever 90 is connected to the hollow shaft outboard of the raised multiple thread. At the other end of the shaft develops to the shape of a cone 91. In a desired dimension the contour changes to that of a sleeve 92. Multiple vanes 93 in contour similar to multiple threads 89 are superimposed around the outside of this sleeve. The sleeve beyond the vanes enlarges in diameter in a gradual arc to form venturied area 94 between the sleeve and the annular chamber 80. The inner end of the sleeve tapers back at an angle to the horizontal plane to the same diameter as the sleeve on which the vanes 93 are mounted.
Ports 95 are located around the circumference of this tapered face 96 and an inner sleeve 97 is positioned within the sleeve 92.

The inner sleeve 97 is provided with air and fuel mix-ture inlets 98 through the surface of the cone 91. The inlets 98 open to the area 99 between the inner and outer sleeves. This area communicates with the fuel mixture ports 97 in the tapered face 96 of the outer sleeve 92.

In the event that fuel oil is used to fire the furnace, fuel oil is supplied to the fuel burners through the supply tubes 100 connected to the oil supply valve 101. This supply tube 100 engages through the hollow shaft 88 and communicates with the fuel jets 102.

Powdered fuel is supplied by the fuel siphon 78 positioned through the burner housing 75 in venturi section 77 of this housing.

The control levers of the fuel oil supply valve 101, gas inlet valve 71 and the control lever of the powdered fuel metering rod 103 and 104 respectively, interconnect to the air ~ control lever 90.

: The control lever 90 rotates the hollow shaft 88 on the raised multiple thread 89 through the matched bushing 86 causing the air controlling cone 91 to move towards or away from the sur-face of the venturi 77, thus decreasing or increasing the venturi area 94 between the cone and the surface of the venturi through which the air and fuel mixture passes.

By calibrating the fuel to air mixture in a desired proportion by the adjustment of the rod linkage interconnecting the fuel and air control levers, the desired ratio of the fuel to air mixture is maintained regardless of the fuel burner demand and of the type of fuel being used.

The furnace fuel burner 74 is capable of burning three types of fuels - gas, oil and powdered fuels simultaneously or in any combination of the three fuel types.

The fuel burner 74 is7effect three separate burners, two minor burners designated 106 and 107 and a main burner 108.

In the operation of the minor outer burner 106, air and gas is supplied from the main manifold 69 and the gas inlet valve 71 through the bypass duct 82. This bypass duct is regulated by the damper 83. The fuel mixture is passed through orifices 84 and 85 in the annular chamber 80 to the burner retort area lO9.
The air and fuel mixture moving through the annular chamber 80 to the burner orifices and creates a cooling effect to protect the metal exposed to the burner retort area 109. This cooling effect prevents the erosion and distortion of these metal parts that are exposed to the intense heat generated in this burner retort area.

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In the operation of the inner minor burner 107 the fuel mixture is moved through inlets 98 in the cones 91 to an area between sleeve 92 and the inner sleeve 97 and is emitted through ports 95 in the circum~erence of the tapered face 96 of the outer sleeve 92. The area between the two sleeves is closed at the furnace end of the inner sleeve. The air and fuel mixture moved between the two sleeves protects the metal exposed to the retort 109 by cooling these surfaces.

In the main fuel burner 108 gas is supplied through the gas inlet valve 71 and is premixed in the main air manifold 69.
The air and gas mixture along with the steam received through the steam inlets 70 in the main manifold 69 is impelled by the force generated by the fans 62 or 68. This air, steam and gas mixture may be augmented with powdered fuel and/or fuel oil de-livered through powdered fuel siphon 79 and the fuel oil jets 102, respectively. The total amount of air is impelled through the adjustable venturi area defined by the inner surface of the venturi section 77 and the cone 91. This mixture is then moved through the centrifugal force generating vanes 93 and fixed venturi area 94 to the burner retort area 109 where the combustion gases assimilate or mix with those of thw two minor burners 106 and 107.

The fuel and air mixture is ignited by co~act with the metal surfaces within the retort area 109 of fuel burner in a rotating manner. The centrifugally propelled flame fringe moves transversely over the rim of the burner slowing as the expanding flame pattern rotates and expands to contact the inner refractory 1~58862 surface of the melt drum. Similar rotating flame patterns move toward each other from the opposing fuel burners 74. The rotat-ing flame patterns meet in the centre of the charge portion 20 turning in the same direction.

This flame pattern is accomplished by having the vanes 93 installed on the sleeve 92 mounted clockwise in one burner with the vanes in the opposing burner being mounted anticlockwise.

The temperature of the metal of the annular chamber 75 exposed to the burner retort area 110 is maintained at a level as high as possible consistent with the cooling requirements necessary to protect these metal parts exposed to the intense heat generated within the burner retort area. This is accomplished by manipulating the bypass damper 83 controlling the flow of air and gas passing to the annular chamber of the outer minor burner 107 enroute to the outlet orifices 84 and 85.

By having the surfaces containing the retort area 109 of the fuel burner above the ignition point of the fuel, the fuel ignites spontaneously in contact with the surfaces within this very large burner retort area.

Conventional forced draft burners (not illustrated) project the fuels away from the burner surfaces before they ignite.

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With the furnace in operation the minor burners 106 and 107 never turn off as they bypass the main fuel burner 108.
This continuous operation is essential to protect the surface areas of the main fuel burner 108 that are exposed to the retort area 109.

Each minor section 110 includes a horizontal portion terminating in a downturned flanged opening which matches up with an upturned flanged opening 112 on the outer ends of the main duct portion 69.

The matched flanges are secured by a wrench bolt ~d nut assembly 113, which centres through flanged bushings 114 mounted through the top and bottom of the minor and major sections. The wrench bolt forms the axis of a hinge. By slackening the wrench bolt the fuel burner can be swung away from the furnace body.
The gas supply pipe 71A enters through the inner circumference of the flanged opening 111 so as not to interfere with the swing of the burners. This manifold hinge is collectively designated 116.

The fuel burner herein described is not limited to a metal melting furnace but can be applied generally to any fossil fuel burning device.

- lOS8862 The powdered fuel is fed from a hopper 119 as shown in Fig`. 11. The fuel requirements to the fuel burners are regul-ated by a metering rod collecti~ely designated 120, which in this embodiment is a round metal rod with a slightly tapered end S 121 ana having a raised thread 122 and control lever 104 at its other end. The metering rod poSitionS through a flanged bushing 123 mounted centrally through the cover 124 of the hopper. The hopper is filled through inlet 125 and is vented by an outlet 126 in the hopper lid.

The metering rod is larger in diameter than the hopper outlet 127. The tapered end 121 closes against the inner surface of the hopper immediately above the outlet 127. By moving the control lever 104 thereby rotating the metering rod on the thread 122 in the bushing 123, the rod is raised from contact with the hopper outlet inner face to a clearance that allows a desired flow of the powdered fuel past the hopper outlet metering rod to the powdered fuel siphon 78.

An important feature of the metal melting furnace is the use of tungsten within the melt drum 20. Hydrocarbons are passed over heated brick, such as refractory lining 22, crack to form hydrogen and free carbon, while tungsten has the capability, when heated to white incandesence, to dissociate hydrogen to atomic hydrogen with a short life span of 0.3 seconds. On re-combination of the hydrogen atoms, the heat of formation of mole-cular hydrogen is liberated for the attainment of a flame temperature of 3800C.

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The utilization of these values begins in the design of the fuel burner. This burner is designed to move the combusting hydrocarbons in a long rotating travel, repeatedly moving the combusting gases in contact with t~e hydrogen generating brick surfaces 23 and atomic hydrogen generating tungsten in passage to the furnace exhaust outlet for maximum contact with the brick and tungsten surfaces.

Figure 2 shows tungsten sleeves 128 (serrated on their outer surfaces to increase the surface area thereby increasing the surface exposure) that will withstand temperatures in excess of 4000F which are positioned around tubes 129 of silicon carbide X.T. or equal, a ceramic of great physical strength, high thermal conductivity, with a minimal expansion factor. This ceramic material retains its mechanical strength to approximately 4000F
and is highly resistant to thermal shock.

These serrated tungsten and ceramic tube assemblies collectively designated 130 are located near the inner refractory surface 23 near the top of the melt drum 19. The tube assemblies ~; are supported at one end in sockets 131 positioned in transverse surfaces of the water jacketed charge hopper 41. The other ends are supported in open ended sleeves 132 that extend through the vertical water jacketed end section 118. The tube assemblies 130 are removable through the open ended sleeves 132 that are covered by the flaps 133.

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Figure 12 shows a variation of the melt drum with a large domed portion 22A at either end, one upon each side of the charge portion 21. This design creates great strength to the refractory lining and metal structure, and is particu-larly suited to very large furnaces required a relatively largeliquid metal storage capacity which is stored by the addition of the deep wells.

The construction described provides preheating to the metal being fed to the hopper and the source of heat for this preheating is of course the exhaust gases from the drum which pass through the charge port 41 through the charge hop-per 40 and into the preheating oven 42 each time the charge opening is aligned with the base of the charge hopper, this occurring twice in each cycle.

; lS Finally, pouring spouts 11 are provided within the charge portion 20 of the drum, one at each end thereof and usually adjacent to the uppermost side of the drum when it is in the position shown in Figs. 6 and 14 with the charge port 41 in alignment with the charge hopper 40.

One or the other of these may be plugged so that by tilting the table as aforementioned, metal can be withdrawn from one or the other.

In operation, the drum is rotated first in one direc-tion and then in the other by means of the motor 28 and metal to be lOS886Z
melted is fed from the conveyor through the charge hopper into the drum each time the charge opening aligns with the base of the charge hopper.

Heat is supplied by burners at each end of the drum as hereinbefore described and melts when the refractory melt drum or retort reaches the proper temperature.

Figure 14 shows the drum with the charge opening in alignment with the hopper whereupon it moves to the position shown in Fig. 13. The motion then reverses back to the position shown in Fig. 14 at which time a further charge may be received and then moves on the other half of the cycle and in the opposite direction to the position shown in Fig. 15.

As soon as the melt temperature is reached and the metal is ready for pouring, the air motor is sequenced so that once each revolution or cycle, the drum tilts slightly further in one direction to the position shown in Fig. 13 under which circum-stances the level of the molten metal is above the pour spout 11 and molten metal pours from this spout into moulds which may be provided.

The weight of metal extracted on each cycle should equal the weight of metal added through the charge opening so that once the melt temperature is reached, the total amount of metal remains relatively constant throughout the operation of the furnace until it is desired to close down the furnace whereupon the conveyor 48 is halted and metal is poured from the drum until same is empty.
This may be facilitated by tilting the drum along the longitudinal axis as hereinbefore described, by the agency of the hydraulic jack 107.

Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims lQ without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

Claims

WHAT I CLAIM AS MY INVENTION IS:
(1) A furnace adapted for continuous operation in the reduction of metal such as scrap, ingots and the like to molten metal ready for pouring; comprising in combination a supporting frame, a substantially cylindrical drum mounted within said frame, for partial rotation in alternate directions, said drum including a charge portion and at least one combus-tion chamber portion, a fuel burner assembly at one end of said drum, a stationary sleeve assembly surrounding the charge portion of said drum, said drum partially rotating within said sleeve assembly, a charge port in said charge portion of said drum, a charge hopper in said sleeve assembly communicating with said charge port when said charge port aligns with the base of said hopper, a partially annular exhaust duct in said sleeve assembly surrounding said charge portion of said drum, the interior of said drum communicating with said exhaust duct through said charge port when said charge port is misaligned from the base of said hopper, at least one molten metal pour-ing spout through the wall of the combustion chamber portion of said drum, and a source of power to partially rotate said drum as aforesaid.

(2) The furnace according to Claim 1 which includes a water jacket surrounding said charge portion of said drum between said drum and said exhaust duct and an air duct sur-rounding said water jacket, said air duct being operatively connected to said fuel burner assembly and acting as the air supply therefore, and means to preheat said air supply by the water in said water jacket, said means including a heat ex-changer through which said air and said water passes, and conduit means operatively connecting said water jackets with said heat exchanger.

(3) The furnace according to Claim 1 which includes a source of heated steam for said fuel burner assembly and means incorporated in said fuel burner assembly to initiate a slow rotating action to the flame from said fuel burner as-sembly whereby said flame contacts the wall surfaces of said combustion chamber.

(4) The furnace according to Claim 2 which includes a source of heated steam for said fuel burner assembly and means incorporated in said fuel burner assembly to initiate a slow rotating action to the flame from said fuel burner as-sembly whereby said flame contacts the wall surfaces of said combustion chamber.

(5) The furnace according to Claims 3 which includes an air duct operatively connected to said fuel burner assembly and acting as the air supply thereto and in which said last mentioned means includes a plurality of vanes situated radially and at an angle within said air supply to provide slow rota-ting action to said air supply immediately prior to same en-tering said fuel burner assembly.

(6) The furnace according to Claim 4 in which said last mentioned means includes a plurality of vanes situated ra-dially and at an angle within said air supply to provide slow rotating action to said air supply immediately prior to same entering said fuel burner assembly.

(7) The furnace according to Claim 1 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(8) The furnace according to Claim 2 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven to said vent stack, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(9) The furnace according to Claim 3 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven to said vent stack, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(10) The furnace according to Claim 4 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven to said vent stack, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(11) The furnace according to Claim 5 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven to said vent stack, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(12) The furnace according to Claim 6 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven to said vent stack, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(13) A method of reducing metal scrap, ingot and the like to molten metal for pouring on a continuous basis consisting of the steps of partially rotating a refractory drum first in one direction and then the other, supplying a source of heat through one end of said drum, adding metal scrap, ingot and the like to said drum through a charge opening therein, each time said charge opening reaches a metal loading position, and pouring an amount of molten metal from a pouring spout in said drum on each cycle substantially equal in weight to the weight of the scrap, ingot and the like added to said drum.

(14) The method according to Claim 13 which includes the addition of heated steam to said source of heat.

(15) The method according to Claim 13 which includes preheating the scrap, ingot and the like prior to adding same to said drum.
(16) The method according to Claim 14 which includes preheating the scrap, ingot and the like prior to adding same to said drum.

(17) A furnace adapted for continuous operation in the reduction of metal such as scrap, ingots and the like to molten metal ready for pouring; comprising in combination a supporting frame, a substantially cylindrical drum mounted within said frame, for partial rotation in alternate directions, said drum including a centrally located charge portion and a combustion chamber portion on each side of said charge portion, a fuel burn-ing assembly at each end of said drum communicating with said combustion chamber portion thereof, a stationary sleeve assembly surrounding the charge portion of said drum, said drum partially rotating within said sleeve assembly, a charge port in said charge portion of said drum, a charge hopper in said sleeve assembly communicating with said charge port when said charge port aligns with the base of said hopper, a partially annular exhaust duct in said sleeve assembly surrounding said charge portion of said drum, the interior of said drum communicating with said exhaust duct through said charge port when said charge port is misaligned from the base of said hopper, at least one molten metal pouring spout through the wall of the combustion chamber portion of said drum, and a source of power to partially rotate said drum as aforesaid.

(18) The furnace according to Claim 17 which includes a water jacket surrounding said charge portion of said drum between said drum and said exhaust duct, and an air duct surrounding said water jacket, said air duct being operatively connected to said fuel burner assemblies and acting as the air supply therefor, and means to preheat said air supply by the water in said water jacket, said means including a heat exchanger through which said air and said water passes, and conduit means operatively connecting said water jackets with said heat exchanger.

(19) The furnace according to Claim 17 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(20) The furnace according to Claim 18 which includes a metal carrying conveyor connected with said hopper and means to preheat metal carried by said conveyor prior to said metal enter-ing said drum, said means including an enclosure for said conveyor comprising a preheat oven, a vent stack along the length of said enclosure, the exhaust from said drum passing through said hopper and said preheat oven, and means to tilt said drum endwise within limits, said last means including means to support said frame transversely for limited pivotal action and adjustable means between said frame and a supporting surface upon which said frame rests, to adjust the angle of said frame and hence the angle of the longitudinal axis of said drum.

(21) The furnace according to Claim 1 which includes a plurality of tungsten sleeve assemblies within said combustion portion of said drum, and means to mount said tungsten sleeve assembly.

(22) The furnace according to Claim 21 in which said means to mount said tungsten sleeve assemblies including ceramic mounting tubes, means to support said mounting tubes by the ends thereof to said drum, and tungsten sleeves surrounding said moun-ting tubes, said sleeves being serrated on the outer surfaces thereof to increase the surface area of said sleeves.

(23) The furnace according to Claim 17 which includes a plurality of tungsten sleeve assemblies within said combustion portion of said drum, and means to mount said tungsten sleeve assembly.

(24) The furnace according to Claim 23 in which said means to mount said tungsten sleeve assemblies including ceramic mounting tubes, means to support said mounting tubes by the ends thereof to said drum, and tungsten sleeves surounding said moun-ting tubes, said sleeves being serrated on the outer surfaces thereof to increase the surface area of said sleeves.