KR810001641B1 - Plasma arc vertical shaft furnace - Google Patents

Abstract

A vertical shaft furnace comprising melting chamber having upper and lower chamber, outlet means in lower chamber portion communicating with molten metal collecting means for continuosly withdrawing molten metal therefrom, a plurality of downwardly-inclined openings arranged in two vertically spaced plances and in spaced relation about the lower chamber portion, plasma arc torches arranged in said openings, means for connecting an electrical power source between torches and metal charge and means connected to torches for extending and retracting torches relative to lower chamber portion into operating positions thereof.

Description

Plasma arc vertical shaft haft furnace

1 is a partially cutaway side view showing a cross section of a vertical axis using a plasma arc torch installed on a sidewall in accordance with the present invention;

2 is a horizontal sectional view of the vertical axis of the present invention taken along line II-II of FIG.

3 is a horizontal cross-sectional view of the vertical axis of the present invention taken along line III-III of FIG.

4 is a side elevational view in partial cross-section showing the plasma arc torch settling in the sidewall of the vertical axis of the present invention.

TECHNICAL FIELD The present invention relates to electric arc furnaces, and more particularly, to an apparatus for rapidly melting raw metals and scrap metals. In particular, the present invention relates to a vertical axis which enables the continuous supply of molten metal and in particular has a plasma arc torch installed on the side wall for use of a continuous casting machine.

For subsequent processing, the melting of metal charges fed continuously or semi-continuously in a furnace, ie in a continuous casting machine, requires a great amount of heat energy, which is almost lost to radiation by conduction and conduction from the furnace. . In order to efficiently improve and minimize the amount of heat lost to the environment, it is important both economically and in energy conservation cells to achieve melting in the shortest possible time. It is known that the use of plasma arcs for molten metal in furnaces entails much higher heat, for example 9,727-19.727 ° C., which can greatly improve the melt rate. It is also known that the heat transfer effect from the plasma arc torch to the scrap metal charge is improved by the selective position of the plasma arc torch, also provided on the sidewall of the figure. Such plasma arc mechanisms are described, for example, in US Pat. Nos. 3,422,206 and 3,749,803. However, such prior art cannot apply molten metal continuously to a continuous casting machine, frequently delaying the tapping of molten metal, resulting in waste of time and substantial loss of thermal energy. Other conventional furnaces also used plasma torches to re-dissolve the cooling castings and to refine consumer metal bars into ingots, which were exemplified by the furnace apparatus described in US Pat. Nos. 3,496,280 and 3,736,361. have.

In general, however, the use of plasma arc torch in metal melting furnaces is limited in cooled metal melting furnaces and intermittent furnaces as described above. Although the vertical fuel combustion furnaces for continuously dissolving scrap metals described in, for example, US Pat. Nos. 3,199,977 and 3,788,623 are known, for the continuous supply of molten metal for casting in a continuous casting machine within the known range, Vertical furnaces have been used. In conventional fuel-fired furnaces, intermittent or semi-continuous charging with scrap metal into the furnace causes the charge to be dropped into the furnace via a hole adjacent to the top of the furnace and also to place the charge in a disorderly arranged position, This was accomplished by forming a vertical column of scrap that descends from the furnace axis as the charge dissolves. After charging, the charging inlet is closed and then additional scrap material is loaded intermittently if necessary in the same way.

As described in the aforementioned U.S. Patent Publication No. 3,199,977, this disordered charging method reduces the impact on metal loading and thus enhances the dissolution rate. However, the time-based charging method of the vertical melting furnace is not practical if the plasma arc torch is used to dissolve the metal charging. This is because the torch tip extends into the furnace, which is regularly located below the inner wall, and is located adjacent to the metal charge so that it is maintained in proximity to the arc between the torch electrode and the charge. As a result, the torch tip can be continuously damaged by the scrap material or the scrap metal charge being lowered.

In view of the foregoing, in a vertical metal melting furnace using a plasma arc torch mounted on the side wall, a significant amount of heat of introduction to the metal charges has been improved and effective production, i.e. minimizing heat loss in the shortest time, It becomes clear that it is necessary to continuously supply molten metal for use.

Therefore, the object of the present invention is to be suitable for intermittent charging with metal in continuous operation, and also to use the plasma arc torch installed on the sidewall to rapidly dissolve the charged metal in order to minimize the heat loss to the surroundings. It is to provide a vertical shaft melting furnace for supplying metal to the continuous casting machine.

It is another object of the present invention to be installed at the charging inlet and the sidewalls below it, and also to place a plurality of plasma arc torch inclined downward and spaced vertically at the upper and lower sides for preheating. To provide a vertical shaft melting furnace having a plurality of plasma arc torch for dissolving scrap metal charged into the furnace through.

It is still another object of the present invention to provide a vertical axis having a plasma arc torch installed on the sidewall for dissolving the charged metal quickly, that is, the plasma torch is not damaged by the loading or dropping of the charged metal.

It is still another object of the present invention to provide a refractory gas on the inner wall of the vertical shaft furnace to protect the plasma arc torch installed on the sidewall by injecting or lowering the scrap metal charged into the furnace while using the plasma arc torch.

Briefly described, several of the obvious objects of the present invention described so far are achieved by providing a melting furnace having a vertical axis melting chamber including a charging inlet at the top of the furnace. Here, scrap metal through the top of the furnace can be intermittently loaded when the furnace is applied to allow for longitudinal placement of the metal. The lower part of the furnace extends the torch under the inner wall and is provided with a number of downwardly inclined plasma arc torch for withdrawing the torch. Plasma arc torches are arranged on the top and bottom vertically spaced planes to preheat and dissolve the charged metal, respectively, and the torches in the planes are arranged at right angles to the furnace walls. At its lower end, the furnace has a floor arranged to collect molten metal of continuous metal discharged into a tundish or metal refiner installed via an outlet prior to casting in a continuous casting machine. According to another important aspect of the present invention, the inner walls of the lower furnace section are provided with refractory elements which extend radially inwardly towards the furnace axis, which at least partially encloses the plasma arc torch when scrap metal is charged to the furnace and columnar scraps. This prevents metals from being damaged if they are lowered in the furnace during operation.

Preferably, these refractory elements are inverted, ie substantially U-shaped, in order to protect the torch tip from the plasma arc torch as well as its horizontal side. When the torch extends in close proximity to the charge to collide with the arc, these refractory elements extend inward and take a radial direction at a sufficient distance to protect the torch tip.

The nature of the present invention, together with the other objects, advantages and features of the present invention disclosed so far, will be more clearly understood with reference to the following description, appended claims and some drawings illustrated in the accompanying drawings.

Referring to the drawings in which like parts have the same reference numerals throughout, the vertical axis is generally indicated by reference numeral 10 for the purpose of continuously dissolving the metal. The furnace 10 extends vertically, preferably in the shape of a cylindrical shape, through which the metal jaws for melting, such as scrap metal copper cathode pieces, are charged with gravity force through the inlet 14. Inner cylindrical melt chambers are suitable. The charging hole 14 is provided with a cover 16 to close the charging hole when metal is not charged in the furnace. If it is desired to carry out the elution of the metal charge under an adjusted atmosphere, ie a controlled atmosphere which is adjusted by changing the pressure or the gas of the atmosphere, or both, insert the charge 14 into the lid 16. A device for sealing can be installed.

The furnace wall 20 does not need to be specifically described, which consists of an outer cylindrical metal sheath 22 and a fire resistant lining which may consist of, for example, carbide bricks or other suitable fire resistant walls capable of withstanding the high temperatures present in the melting chamber. 24 may consist of one or more layers of insulating material or insulating brick disposed between the metal sheath 22 and the high temperature resistant fire resistant lining 24.

The bottom or floor 26 of the melting chamber 12 is also formed of a refractory material and has a concave bowl designation (28) to provide a device for collecting molten metal pools (P) dissolved in the furnace. do. The refractory outlet conduit 30, which is inclined to Hava, only allows the outflow of the molten metal only after the surface of the metal pool P is substantially equal to the horizontal cross-sectional area of the melting chamber 12. 20) is extended throughout the day. After initiation of the charge of the charge, the level of the melt (P) reaches the level of the conduit (30), and the molten metal is discharged to another apparatus, such as a continuous installed runish 32 or molten metal refining system. The molten metal from the device is known and discharged to a continuous casting machine which continuously produces cast metal bars in a manner not particularly shown. If the melt chamber atmosphere is adjusted, the lundy 32 is provided with a shield 33 for forming an effective hydraulic seal in the outlet conduit 30.

The heat supply regime required for the continuous dissolution of the metals charged into the furnace is shown in a number of plasma arc generators, or torch 34, 36 as also known plasmatron and the power supply thereof and in FIG. Consisting of connected connections.

The present invention and its structure and plasma arc torch suitable for use in the work are known in the art, and the detailed description thereof is considered unnecessary to fully understand the present invention. Such conventional plasma arc torch is described in detail in US Pat. Nos. 2,922,869, 3,147,330, 3,194,941 and 3,673,375. Plasma arc torches 34 and 36 are spaced at right angles to the dissolution chamber axis with vertically spaced planes as best shown in FIGS. The upper torch 34 is a preheating torch for preheating the metal charge lowered by gravity downward through the melting chamber, and the lower torch 36 completely converts the preheated metal charge to the dissolved state. It is a work or dissolution torch that supplies the amount of heat added to it.

As shown in FIG. 1, plasma arc torches are conventionally provided via an electrical connector 41 via one electrode of the high voltage power supply 40 and also via the electrical connector 41 to the floor 26. Is connected to the other electrode connected to the electrode 42 located on the concave surface 28 of. The electrodes 42 are arranged to make electrical contact with the metal charged into the furnace when the arc operates to discharge with the metal charge. The electrode 42 then maintains electrical contact with the metal charge via molten metal pool P during the continuous furnace operation.

Each of the plasma arc torch 34, 36 is provided with a fire resistant shroud 44, 46. The fire resistant shroud extends substantially internally radially towards the axis of the fire resistant structure, preferably the melting chamber 12, in the above embodiment, and also encompasses the torch tip on at least three sides, in particular the top and horizontal sides of the torch. It is composed of the surrounding fire brick The upper sides 44 ', 46' of the refractory shroud are inclined or stepped to guide the load which is reinforced downward towards the furnace axis and also to prevent the impact of the metal load on the top surface of the shroud. . Preferably the horizontal sides 44 ″, 46 ″ of the shroud extend to the floor 26 of the furnace thereby providing better structural support.

The purpose of this shroud structure is to prevent damage to the plasma arc torch tip by the falling of the metal pieces charged into the furnace through the charging hole 14 and by the columnar metal passing downward through the melting chamber during continuous operation of the furnace. It is to prevent. It will be appreciated that the torch tips must be fully withdrawn from the melting chamber below the internal refractory lining 24 to prevent damage to the torch tips without provision of the shrouds 44 and 46. As such, the metal charge is immediately located adjacent to the charge opening from which the torch extends. If the arc becomes capable of causing metal charges and discharges under these conditions, the torch must withdraw further along the arc length into the furnace wall, thereby unnecessarily heating the furnace wall and consequently the heat loss of the furnace around it. This is increased and effective work is reduced. Thus, the shrouds are located closer to the furnace axis, and it is effective to change the maximum heating zone generated for the position plasma arc further away from the furnace wall structure.

Referring now to FIG. 4, a plasma arc torch 34 or 36 extending through the furnace wall 24 is shown with a torch tip closely adjacent to the metal charged into the furnace for the first discharge with the arc. have. After the arc has discharged and stabilized, the torch 34 or 36 is withdrawn to the arc working length position indicated by the dashed line in FIG. 4 by means of the actuating device 48 by a known working method. As illustrated, the torch is positioned directly above the top wall 44 'or 46' in such a way that the metal piece that is charged and lowered into the furnace by gravity is substantially prevented from being damaged in contact with the plasma arc torch tip. It is also located between the horizontal sides 44 '' and 46 '' of the shroud. Even when the plasma arc torch is withdrawn to the arc working length position, the torch tip is still protected from damage and advantageously extends into the melting chamber space below the inner surface of the refractory lining.

In view of the foregoing it is evident that according to the present invention a novel vertical axis has been provided which uses a plasma arc torch to melt the metal charge to continuously supply molten metal to the continuous casting machine.

While the preferred embodiments have been specifically described and illustrated herein, many modifications and variations are possible to the invention, in particular with respect to the appearance of the shroud within the scope described above and without departing from the spirit and scope of the invention. It is obvious that changes are possible within the scope of the claims.

Claims (1)

A vertically elongated melting chamber having an upper and lower chamber portion, consisting of an upper chamber portion, a refractory material and a floor, which continuously descend on a column during the operation by having a device for gravity-loading the metal into the melting chamber during operation of the furnace A floor 26 comprising a device for collecting molten metal pools in a lower chamber portion furnace having an inner wall, an outlet connected to the molten metal collection device for continuously discharging application metal in the lower chamber portion In the vertical axis for melting the metal material consisting of a device 30, a plurality of downwardly inclined charges 14 arranged at regular intervals with respect to the lower chamber portion, the torch 34, 36 and To extend and withdraw the device to connect the power source between the metal charges and torch in the lower chamber section to the working position By means of a device connected to the torch.

Images