US1680155A - Fuel-heated furnace and converter using preheated air - Google Patents

Description

Aug. 7, 3928.

O. LELLEP FUEL HEATED FURNACE AND CONVERTER USING PREHEATED AIR Filed Oct. 29, 1925 2 Sheets-Sheet l INVENTOR. Ir J Aug, 7, was. wmws O. LELLEP FUEL HEATED FURNACE AND CONVERTER USING PR EHEATED AIR Filed Oct. ,29, 1923 2 Sheets-Sheet 2 6 12 28% H J- n 27 ee 2 1 3 12 e IN V EN TOR.

Patented Aug. 7, l92%.

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OTTO LELLEI, F EGYPT, PENNSYLVANIA, ASSIGNOR TO THE INTERNATIONAL N ICKEL COMPANY, OFYNEW YORK, N. Y., A CORPORATION 0F NEW JERSEY.

FUEL-HEATED FURNACE .AN'D CONVERTER nsrn'e rnnnna'rm lam.

Application filed October 29, 1923. Serial Ito. 671,496.

My invention relates" to. improvements in furnaces and converters in which a molten.

bath of metal, or metal alloy and metallic compounds is treated with gases, said gases being blown over the surface or through the body of the molten bath.

In furnaces and converters embodying my invention the charge may be introduced in the solid state or in the molten state (as from a preceding metallurgical operation).

The main object of my invention is to provide the proper temperatures in connection with treating a nickel-containing matte with a pressure blast, and more specifically,

air of the blast which contacts with the molten matte itself.

Another object of my invention is to rovide further suitable structures in whic to carry out the processes and reactions covered in my Patent No. 1,278,176 dated September 10, 1918, and in my application for patent Serial 'No. 630,618 dated April 7, 1923. (The processes and reactions referred to are applicable in particular to the converting of nickel containing matte into refinednickel or nickel-copper alloy.) 2 The the application are tions can be carried out in a readily controlled manner and with the least expense for equipment, maintenance, and operation,

in which air is preheated, preferably in a regenerative air heater, and is used at pressures and temperatures above the 'usual practice bothin combination with fuel and gvitgout fuel to act on a molten metallic at A further object of my invention is to provide structures in. which the hot exit gases flow through the recuperator or regenerator in directions opposite to the incoming air, exchanging heat, but in which the travel of gases through the burners or to attain this temperature by preheating the which metallurgical operations and reac-' air heaters.

tuyeres and furnace or converter laboratory is alwa s in one direction only or in What I call in unifiow in a closed furnace. A further object of my invention is to provide structures forming a furnace or converter adapted to be conveniently changed from the position in which the blast im'- pinges on the surface of the molten bath to the position in which the blast blows through the body of the molten bath, or vice versa.

' My invention consists of the new and im-" proved structures and materials forming the furnace or converter proper, which I will hereafter call the unifiow laboratory, the connecting passages for blast and exit gases, the heat regenerators in which air and direction, t e supports for the various parts, and in the method of using preheated air at high pressure and at a temperature above the igniting point of fuel, either unmixed or mixed with fuel in oxidizing, neutral or reducing proportion to act upon the surface or through the body of the molten metallic ath, in a closed furnace or converter for the purpose of refining the metal of said bath. attain my objects by the structures and methods fully disclosed in the following description and accompanying drawings, in which:

Fig. 1 is an elevation of my metal refining apparatus, partially in section.

Fig. 2 is a cross section of the closed uni.- flow laboratory on line 2-2 of Fig. 1.

Fig. 3 is an elevation of my metal refining apparatus showing a tangential blast, low arch, closed uniflow laboratory partially. in section.

Fig. 4 is a plan view shown in Fig. 3 partially of the apparatus in section. 7 Referring to the drawings, in which similar parts are given the same numbers,

1 is a unifiow laboratory. The line 2 indicates the level of the molten bath when the blast of preheated air (with which fuel may be mixed) isused to impingeon the surface of the bath. 3 is a connection shown partially in section for preheated air. 4 is a 7 connection for fuel, preferably for gas, or vaporized oil. 5 and 5 are two regenerative Regenerator 5 is in position over the exit opening 6 for hot waste gases from laboratory 1, and is receiving heat from the waste gases. 7 is any suitable refractory material such as magnesite in which are holes 8 and which is adapted to be a supporting diaphragm for refractory particles 9 which may be of any suitable material such as broken magnesite ininch pieces. The diaphragm 7 rests on a loose checkerwork of blocks 10 of refractory material which is adapted to distribute the hot waste gases over the area of the perforated diaphragm 7. Any suitable arrangement of bricks of refractory material may be used to distribute the hot gases and to support particles 9. The regenerators 5 and 5 are filled with the particles 9 nearly to the top where space is left for the gases to enter or escape at opening 11. The regenerator 5 is in position to give up heat to the incoming air received from connection 12 in which pressure. The air pressure may vary from one inch water gauge up to 10 pounds per square inch. But 3 pounds per square inch is usually'suflicient to produce a jet of gas which'will impinge upon the bath with such violence as to come into contact with the metal with the result that during the oxidation period practically all the free oxygen of the blast will be absorbed by the bath. Air

is furnished by a suitable compressor not shown. The heated air flows through connection 13 to manifold 14 from which connection 3 leads to the tuyere openings 15 through which the blast enters the laboratory 1 at a slight angle to the bath surface 2. In Fig. 1 the line 2, shows the level of the molten bath when the blast impinges on its surface. In dotted line 16 is shown the position of the surface of the molten bath when it is desired that the blast enter through the body of the molten bath. That part of the apparatus which is shown in Fig. 1 is mounted on a platform 17 which rests on bearings 18 and the ram 19. Platform 17 is adapted to be tilted by the ram' 19 of hydraulic jack 20, as it is desiredto have the tuyeres 15 above or below the surface of the molten bath. Any suitable means of tilting the platform 17 may be used.

The regenerators 5 and 5 are supported by a pivotal member21 which is threaded at 22. An antifriction bearing 23 is supported by the member 24' connected to and supported by platform 17, and-a nut and lever 25 furnish means to lift regenerators 5 and 5 out of contact with the valve seats 26 on exit opening 6 and valve seat 27 on connection 13 for the preheated air supply. Blast connection 12 is raised out of contact with the valve seat'28 by lever 29 supported on fulcrum 30. While connection 12 is lifted the blast should be temporarily by-passed. By operating levers 25 and 29 the regenerators 5 and 5 are left free to be rotated on the bearing 23 through an arc of 180 around pivot 21 as an axis. Thus the regenerators are conveniently interchanged in position,

the air is under the heated regenerator 5 being moved to register with air connections 12 and 13 and the cooled regenerator 5 being moved simultaneously to register with hot gas exit 6. The walls of laboratory 1, the generators 5 and 5 the air connection 13, manifold 14 and connections 3 are composed of air tight metal shells 31 lined with refractory material 32. The recess in the arch of laboratory 1 of Fig. 1 is formed to prevent the particles of the bath, lifted by the impinging blast, from being carried intothe regenerator 5 by the waste gases.

In Figs. 3 and 4 are shown an embodiment of my invention in which the uniflow laboratory 1, is' made circular and of low arch and with hot waste gas opening 6 in the center. The tuyeres 15 are placed preferably in tangential posit-ion, though other positions will do. The manifold 14 extends around the furnace and communicating passages 33 are formed directly in the lining of refractory material. Holes and plugs 34 are provided as peep holes and for tuyere punching purposes. Fuel is admitted into passages 33 through fuel supply connections 4. In this type of laboratory in which the blast preferably impinges at a slight angle on the surface 2 of the molten bath the tilting mechanism shown in Fig. 1 may be omitted, otherwise the operation of the regenerators and the furnace is similar to apparatus shown in Fig. 1. Charging doors, tap holes, peep holes and tuyere punching holes are provided in all the laboratories but not shown as they are of conventional character.

Where my laboratory is to be operated with the tuyeres 15 above the surface 2 of.the molten bath, the flame resulting from the mixture of the jets of highly preheated air and the fuel is ejected from the burners with about 2 pounds pressure difference. In this case the flame blast penetrates partly into the molten bath, impinges against and rubs violently over its surface, thus causing a practically instantaneous reaction between the constituents of the flame and the bath. The fuel burns generating heat and, flame isoxidizing, sulphur is burned out, in the case of nickel or nickel-copper metal or 'matte; or any other oxidizing effect desired is produced. The flame may be made neutral or reducing, by adjusting the proportion of fuel. Thus it is possible to agitate and wash a bath with a neutral flame to remove any dissolved gases or it is possible to deoxidize with a reducing flame a bath which had been previously overoxidized. The hot waste gases are expelled through the exit opening 6 into the regenerator 5 which is to receive heat. As soon as regenerator 5 is heated up the air flow is by-passed away from the laboratory while the regenerators are interchanged m position. After such interchange is accomplished the air if theaaaaiaa burners 15 through connections 3 lined with refractory material.

When the fuel is injected into the rapidly flowing jets of preheated air at vpoints near the mouths of the tuyeres the fuel mixes imperfectly with the air and burnsonly partly in the tuyeresand in this way the temperature in the tuyeres is prevented from becom: ing so high as to destroy the tuyres. For this reason the length-of the tuyeres is made short preferably not exceeding 8 diameters Y and the fuel is admitted immediately at the entrance of and along the axis of the tuyere. With carefully constructed apparatus it 1s theoretically possible to burn out sulphur from nickel matte by a blast of air preheated to about 2500 F. without using fuel. However, some fuel will be needed in mixture with such preheated-air to heat up the bath. to the reaction temperature, to remove the final sulphur below 0.5% and for reducing the last oxids.

The ordinary regenerative furnace works with a reversal of direction of the flame in the laboratory in order to alternately heat the regenerators. In my invention the regenerators are made movable and are brought alternately to. register with the exit opening for hot gasesan with the air feed connections. In this way I am able to maintain the flow of the'bla'st through my laboratory in one direction. Where the blast flows only in one direction the tuyeres can be of small cross section, adapted to be used under high pressure and gas jet velocities. 1

By making the regenerators movable the principle of a uniflow of gases is obtained in a simpler manner than that in which the regenerators are stationary and the hot waste gases alternately piped to One regenerator and thento the other and the preheated air is led alternately from one regenerator and then the other to the tuyeres of a uniflow laboratory. Such use of stationary regener 'ators. involves elaborate pipin and valves for hot gases which are very di cult to maintain at the temperatures needed.

The shape of the laboratory is not restricted to the round tangential type or to the rectangular box type as shown in the drawings. Converters of conventional shape either of vertical or horizontal type and with the blast through the metal or with a surface blast ('Iropenas type) may be used. a

The small size pieces of refractory material which fill the regenerators, instead of the usual checker brick, absorb and liberate heat quickly and efiiciently which allows of short periods of reversal which in turn makes, possible small light weight and inexpensive construction. Light weight construction makes movable regenerators prac tical.

Preheating the air to a high temperature makes the fuel consumption for my process a small fraction of that in a direct fired cold air furnace or converter. It is evident that my purposes may be embodied in a wide variety of structures without departing from the spirit of my invention.

I claiml. In the treatment of nickel-containing matte or metal, the step consisting in applying a pressure blast of preheated air directly to the molten metal.

2. In the treatment of nickel-containing matte or metal, the step consisting in subjecting the molten matte to the direct action of a preheated pressure blast.

3. In the treatment of nickel-containing matte or metal, the steps consisting in subj ecting the same in molten condition to the direct action of a pressure blast of preheated air, and adding heat to the reaction.

4. In the treatment of nickel-containing matte or metal, the stepsconsisting in subjecting the molten matte to the direct action of a pressure blast of preheated air, and preheating said air by heat generated in the converting reaction.

5. In the treatment of nickel-containing matte or metal, the step consisting in directing a preheated blast of air toward the bath OTTO LELLE P.

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