US1643569A - Furnace for heating or melting metals - Google Patents

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Sept 1927' A. ZILLIACUS FURNACE FOR HEATING OR MELTING METALS Filed March 25. 1926 kml d p w '1 \NZ I 5 an 1 5 a T M INVENTOR flmaflzwm M by WWW

Patented Sept. 27, 4927 ABTUB ZILLIAC'US, OF

DALSBBUK, FINLAND.

FUBNAGE FOB HEATING 0R MELTING METALS.

Application filed March 25, 1926, Serial No. 9?,d25, and in Germany March 23, 1925.

My invention relates to improvements in; furnaces for heating or melting metals. I have found that in the method of heating or melting metal now in use the metal is subject to oxidation even if a reducing flame is used for heating, because even a reducing flame always contains a certain amount of free oxygen and other injurious gases. The object of the improvements is to provide a furnace in which oxidation of the metal being heated or molten is obviated, and with this object in view my invention consists in passing a protective gas such as carbonous oxid over the metal and in contact therewith, and passing the heating flame through the furnace above the said layer of protective gas, so that there is no direct contact between the fiameand the metal,- and the heat of the flame is transmitted to the metal through the protective gas by radiation. Inthe practice of the invention I make use of a protective gas which is manufactured independently of the furnace, or I produce the saidgas within a suitable gas producer. directly connected with the furnace, the preferred method residing in collecting the partly burnt coal coming from the grate oi the furnace, and passing air through the said coal.

For the purpose of explaining the invention a furnace suitable for putting my im proved method into effect has been illustrated in the accompanying drawing, the said drawing showing a sectional elevation of the furnace.

For explaining the invention a furnace will be described in which metalsuch as iron is heated. But I wish it to be understood thatmy invention is not limited to furnaces of this type, and that it applies also to furnaces for melting metal.

In the example shown in the drawing the furnace comprises a hearth as having a proheating chamber 5 at its rear end, the iron being gradually advanced from the preheating chamber 5 to the hearth a. The gases for heating the metal are generated within a fire box m having a grate. 6. At its bottom or rear end the grate bars of the grate 0 are omitted so that the coals partly burnt on the grate a fall into the ash pit at, where they are piled up at the rear of a series of grate bars e into a pile d of glowing coal. The ash pit is separated iron; the main part of the furnace by a partition 'n. The

chambers thus produced are closed in an airtight manner by doors g and o, and each chamber has a supply of air under pressure through pipes it and i. From the lower chamber at the rear of the grate bars e a passage f is passed upwardly to the hearth a, the delivery end of the said passage bein disposed near the bottom of the hearth an being directed so as to deliver the protective gas over the hearth and the metal placed thereon substantially in horizontal direction. Air for supporting combustion is supplied to the furnace through a passage k the delivery part k of which is substantially horizontal, so that the air delivered from the said passage moves along the top wall of the hearth and above the protective gas flowing over the iron. Between the delivery end-of the passage k and the outlet of the firebox on the one hand and the hearth a; on the other hand an elongated fire bridge p is provided, and the portion of the furnace disposed above the said elongated fire bridge has a uniform crosssectional area, the top wall of the furnace being parallel at this part to the top face of the fire bridge p. From the said horizontal part the top wall of the hearth is slightly inclined downwardly and towards the rear of the hearth,

in the operation of the furnace the metal is gradually advanced from the preheating chamber 2 to the hearth (2. Coal is burnton the grate c, and gases produced thereby pass through the horizontal portion of the hearth located. above the elongated bridge g). At this-part air for supportin combustion is admiired to the gases, whic air is likewise delivered into the furnace in horizontal direction. "'l hus the flame has the tendency to move across the hearth in horizontal d1rection without impingin upon the metal. The partly burnt coal fa s mto the ash pit and is piled uat the rear 01? the grate bars a, the sins being collected below the grate bars e an preventing the direct access of air from the passage f. A r uncle through the pipe h,

the grate bars 0 and e otpartly burnt coal d, where it is remained by reason oi the high temperature with the carbon into carbonous acid. The carbonous acid flows throu h the passage f, and it is delivered there rozn substantially horizontal direction across the hearth a. lit appears therefore that the protective gas as well as the flame have a tendency to move in parallel direction across the hearth, so that there is only a limited intermingling of the flame with the protective gas, and noi'le of the ases of the flame have access to the iron 'ocated on the hearth,'the said iron being heated exclusively by radiation and transmission of the heat through the protective gas. While moving through the fore-hearth b the flame is gradually intermingled with the protective gas, which is therefore likewise burnt. However, notwithstanding the contact of the flame with the metal there is no oxidation because'the metal within the fore-hearth is still cold. Even if there should be a slight oxidation the metal is reduced a ain on the hearth a by the carbonous oxizf When using the furnace for melting metal I prefer to utilize the carbonous oxid y pre-' heating the metal to be molten within the 'fore-hearth 6. Further, the said gases may be re ene'rated in the manner known in the art. owever, I have found that the amount of protective gas is small, so that there is no material loss of gas even if the protective gas is not burnt within the fore-hearth.

In some cases I prefer to dispose the gen erator for carbonous oxid independently of the furnace, and in other cases I buy the car; bonous oxid on the market. in this case however, I prefer to preheat the carbonous oxid before using the same in the furnace.

For regulating the combustion of the coal on the grate c and the generation of carbonous oxid the pressure of the air su plied through the pipes h and z is regulated To show such regulating means valves r and s have been shown in the drawing.

I claim:

1. A furnace for heating metal, comprising a hearth, means for producing a layer of a protective gas on said hearth for enveloping the metal on said hearth, and means to pass a heating flame across said hearth and above said protective gas.

2; A furnace for heating metal. comprising a hearth, means for delivering a current. of a protective gas substantially in horizontal direction across said hearth, and meaps for delivering a current of heating gas substantially in horizontal direction reaaeee gas sup lied thereto.

4. A rnace for heating metal, comprising a hearth, a fire box having its ash pit divided into an upper and lower chamber, the lower chamber being adapted to receive partly burnt coal from the grate of said firebox, a passage leading from said lower chamber to said hearth and opening into the same substantially in horizontal direction, and means to supply air respectively through said grate and lower chamber of the fire box and the partly burnt coal piled up therein.

5. A furnace comprisin a hearth, a fire box, an elongated fire bridge intermediate said hearth and fire box, the passage above 'said fire bridge having substantially uniform cross-sectional area, a partition dividing the ash pit of said fire box into an upper U and lower chamber, the lower chamber be ing connected with the art of the fire box above 'the grate thereo for collecting the partly burnt coal from said grate, a passage connecting said lower chamber with the hearth and opening into said hearth substantially in horizontal direction, means to supply air respectively to the 11 per and lower chambers, and means to supp y air for supporting 'combustion to the part of the furnace above said fire bridge and in a direction substantially parallel to said hearth.

6. A furnace comprising a hearth, a preheating chamber at the rear of-said hearth; the top wall of the said furnace above said hearth being slightl inclined downwardly and towards said pre eating chamber, means to supply a protective gas to said hearth near the bottom thereof, and means to supply heating gas to said hearth above said protective gas and substantially in a direction parallel to said hearth.

In testimony whereof I hereunto afiix my signature.

Aft-TUE ZILLIACUS.

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