US1311807A

US1311807A - Combustion process and apparatus for practicing the same

Info

Publication number: US1311807A
Authority: US
Publication date: 1919-07-29
Anticipated expiration: 1936-07-29

Description

U..A. GARRED. COMBUSTION PROCESS AND APPARATUS FOR PRACTICING THE SAME.

APPLICATION FILED MAYZS, I917.

Patented July 29, 1919.

UNITED STATES E ULYSSES A. GARRED, OF NEW YORK, N. Y., ASSIGNOR T GARRED-CAVERS CORPORA- TION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Specification of Letters latent.

Patented-July 29, 1919.

Application filed May 25, 1917. Serial No. 170,833.

To all whom it may concern:

Be. it known that I, ULYSSES A. GARRED,

' a citizen of the United States, residing at tailed description.

Elmhurst, in the borough of Queens, in the county of Queens, in the city of New York and State of New York, have invented certain new and useful Improvements in Combustion Processes and Apparatus for Practicing the Same, of which the following is a specification. The invention relates to burning pulverized fuel in such manner as to increase, intensify and'concentrate the heat at a particular place so that, for example, the smelting or ores and many other operations may be accomplished more economically than heretofore. In any heating by combustion the degree of temperature which can be attained depends on the balance between the number of heat units developed and those disappearing in a unit of time; and in the present invention I increase the speed of development-and thereby the temperature. In other aspects the invention relates to an improved process and apparatus for smelting or melting ores, metals and other materials, with economy in cost of apparatus, fuel and operation and reduction of waste. The invention is of especial value in such operations as smelting or melting ores,

metals and other materials and has been developed primarily in its application to blastfurnace work as a new smelting or melting process and apparatus giving economy in cost of apparatus, fuel and operation, but I desire to be understood as recognizing and claiming also other applications of the invention in its broader aspects, the objects and-advantages of which will appear more fully in connection with the following de- In the drawing is shown a section of a furnace illustrating characteristics of the invention and adapted to its ractice. Since many features of construction will vary according to the circumstances and many of the mechanical parts availed of are in themselves well known, the drawing .is more or less diagrammatic and illustrative; and since the furnace may'be of any desired length (by obvious'elongations and multiplication of parts) and its novel features are observable in a cross-section, the drawing presents that view. The drawing shows a furnace comprising a space orchamber 1 for the charge of ore or other material, provided at its top 2, with means for admitting the charge, preferably a selfclosing door well known in blast-furnace practlce, with one or more openings 3, preferably provided with dampers, leading to the flue L. The walls are. of a construction adapted to withstand heat, as refractory brick or water-jacketed, and are preferably comparatively close together near the bottom so as to leave a comparatively narrow or contracted space, indicated at 5, where the space or chamber 1 opens into the space or chamber 6 so that successive portions of the charge of ore or material may pass down thereinto. In the drawing, the chambers l and 6 are shown as of separate construction with a space between them, which space is luted with magnesite cement, sand, clay or the like, but this separation is provided for the convenient independent repair of the portions of the furnace which require more frequent replacement and, for purposes of operation, the spaces or chambers l and 6 constitute a single chamber. The boshes 7 and walls 8 of the combustion chamberare, also preferably of the usual heat resisting construction, and the bottom 9 is provided with the usual tapping devices to conduct away molten or melted material.

Entering the space or chamber 6, preferably at both sides, are nozzles 10 of apparatus for injecting powdered fuel and air. Such apparatus, as. is well-known, consist of a hopper or receptacle for holding the pulverized fuel with a. worm or other feed therefrom conducting the fuel into the path of a current of air impelled by com pression or otherwise, so that the fuel is mixed with the air and injected. Since the nvention contemplates the use of known inec-ting apparatus and such injecting apparatus itself as distinguished from the use made of it is not claimed as new herein, the

ecting apparatus is not shown.

It will be observed that the furnace thus illustrated presents certain novel features, as follows It provides close to the bottom of the charge a restricted space or spaces for combustion and means for injecting{powdered fuel and air thereinto, said space or spaces for combustion being restricted by the walls of the chamber and the material and consisting'of the interstices between the pieces or particles of the material augmented by such space as results from the melting of the material and such supplemental adjoining space as may be necessary to make the total space for combustion sufficient to develop and properly apply the heat necessary to melt the particular material treated. Supplemental space is shown in the apparatus of the drawing adjoining 'the lower part of the material and is there obtained by some separation of the point where the fuel and air enters the chamber from the material in the chamber, but such separation is to afford space supplementing the other spaces mentioned to constitute together space for combustion and is not such as to result in reverberatory action or to prevent the heat and fuel being forced directly against and into the material. The principal advantage and effect of so providing supplemental adjoining space is that in treating material not easily melted and material in pieces of such size that when piled the interstices between the pieces afford insuflicient space (as, for instance, the usual iron ore), the devel opment and application of suiiicientheat at and within the lower portion of the piled .material from fuel introduced near the lower portion thereof can be successfully accomplished only by thus increasing the size of the combustion space, and even-in treating easily-melted materials (as, for instance, copper-bearing pyrites), where sufficient space f0 the development ofsuch heat as is not obtained from the ore may be provided by introducing the material in. sufficiently large pieces in lieu of adding adjoining space, this particular way of providing suitable space for combustion by a supplemental space adjoining the material is preferable, because it conveniently insures against local chilling of the material, avoids or lessens the delay and loss which may re sult if the material hardens across the mouth ofthe fuel-injecting nozzle when interruptions of proper operation occur from extraneous, causes and tends to insure the better operation of the fuel-injecting apparatus. Whatever the meansby which it is accomplished, provisions must be made for sufficient space for combustion to develop sufficient heat Without permitting reverberatory action. I attribute the fact tnat powdered coal (whichis comparatively inexpensive fuel) has not heretoforebeen successfully used to supply heat for smelting partly to the failure to discover that provision for sufficient but restricted space for combustion without reverberatory action, coupled with forcing thereinto and maintaining therein suflicient fuel and air, secures the development and application at the desired part of the furnace of sufficientheat successfully and cheaply to melt the material. The proper smelting ormelting of ore or other material involves the suitable application of sufficient heat. An object of the present invention is to develop by means of powdered coal a comparatively intense or concentrated heat in a comparatively restricted space, so that smelting and like operationsanay be carried on by burning powdered coal in a vertical furnace or direct contact, with consequent economy. I have found that the comparatively intense or concentrated heat may be developed by forcing sufficient powdered fuel and air into a restricted space and burning it there, and that it is practicable thus to burn comparatively large quantities of pulverized fuel within a comparatively restricted space by supplying and maintaining in that space sufiicient oxygen or air. In all combustion, the amount of action is proportional to the surface of the fuel exposed to air and the finer the fuel, with sufficient access of air, the more rapid is combustion and development of heat and the higher are the working temperatures which can be attained. Looked at in one way, in the present invention 1 am burning the fuel necessary for the operation of the furnace in a quicker way than can be done where, as in the ordinary blast-furnaces, oxidation of descending coke fragments of limited surface is relied upon; and thereby attaining higher temperatures with faster operation.

But since radiation and similar losses are more or less constant, quicker operation means a less consumption of fuel in proportion to the finished product, And since finely-divided fuel is commonly cheaper than the coke now commonly used in blastfurnace practice, there is an economy in this respect also. The desired changes in the charge are accomplished under the known oxidizing, reducing, roasting or other conditions suited to the particular charge, as such conditions are commonlyobserved in practice, but the results are obtained more quickly and art greatlyreduced cost by the development and localization of the maximum temp ature by injecting the fuel in solid finely-divided particles by a stream of directed under considerable pressure against the lower part of the column of the charge.

The furnace is comparatively contracted above said combustion space or spaces. By this arrangementthe charge, while free to contact with the heat, is prevented from coming down into the combustion space or spaces more rapidly than is desirable, and the charge itself is made to assist in securing the pressure.

The furnace is preferably comparatively expanded above its contracted portion. This provides for introducing and presenting enough material to absorb and use substantially all the heat. It also makes the charge serve better as in effect a valve for the pressure under which the powdered coal is burned, bypresenting a comparatively impeded passage (consisting of the interstices between the irregularly shaped pieces or par;- ticles of material) in the contracted portion.

top of the charge and flue that comparatively little dust is carried off. The a'r rangement' indicated in the drawing of a comparatively contracted space with a com-- paratively expanded space thereabove is particularly effective. It will be understood that the precise construction and dimensions will vary with the nature of the material and other circumstances. In some instances a chamber having parallel'walls may servethe purposes but since the charge in such instances will be across the mouth of the fuel;- injecting nozzle, the use of such a chamber should be avoided, except in treating material which is easily melted and introduced in pieces sufiicien-tly large to provide adequate space between them. In other inestances the cross-sectlon of the furnace may be substantially that of a funnel. Usually, an embodiment substantially like that illustrated in the drawing will best accomplish the purposes in View.

The quantity of coal and air forced into, the combustion space and the pressure maintained therein will vary with the heat best suited to the particular purpose. For smelt-' ing operations it will generally be desirable to burn the coal under an air pressure of from, say, a pound to over two pounds and.

usually about a pound and a half, but these figures are to be understood. as very rough approximations, because the pressure will depend chiefly upon the intensity of heat required for the particular material and may be greater or less than the figures indie, cated. For some operations a pressure of a few ounces will be sufficient. Heretofore, so

far as I know, powdered coal has been burnt only in substantially unrestricted spaces,

wherein such attention as may have been paid to pressure has been devoted to providing such draft or exit as to avoid any mate'- rial impeding of the gases, with the result that the pressure, it measured, would be found to be only atmospheric or a trifle above, or even minus. The present inven tion contemplates increasing the pressure to intensify combustion and heat sufliciently to accomplish the purpose in view, that of burning injected fuel, the injection being radial to the mass, at and within the lower portion of the mass to effect the reduction thereof to molten condition.

With the foregoing explanations, the operation of the furnace will be readily understood. In starting the furnace it is usually desirable first to ignite the fuel and develop a considerable amount of heat. The charge consisting of the ore or metal or material to be smelted or melted (whiclnin some cases, may be mixed with some coke, though even in such cases considerably less fcoke need be used than under present practice) may be then fed into the furnace. A portion of the charge in the type of apparatus shown in the drawing will rest on the bottom of the space, or chamber 6 and other portions will extend up into the space or chamber 1. The pressure in the combustion space at or near the base of the charge will be raised by increasing the pressure through the nozzle and by the charge impeding the exit. When the furnace has been sufiiciently charged to sufficiently restrict the combustion space and exit therefrom and. the pressure of air forced into said space with the fuel sufiiciently raised, comparatively intense heat is developed in the combustion space at or near the base of the charge, which converts the same to molten condition, enabling it to pass :out through appropriate taps. As the lower portion of the charge is thus smelted or melted and passes away, other portions of the charge take its place and, the charge being admitted at the top, the operation may be made continuous.

The invention is of particular value because of the economies it effects in fuel, apparatus in proportion to capacity and labor. It will be apparent that the invention relates to the introduction of fuel and the development and application of heat therefrom to effect the melting of the lower portion of a piled mass of material. As is well understood, the treatment of many ores 1n blast furnaces involves the introduction of additions for purposes other than the development of heat from the fuel. added to the charge. Thus, it has long been customary in treating many copper and nickel ores to introduce in additiOn to the ore flux and fuel, a quantity of oxygen (in excess of that necessary for combustion with the added fuel) for combustion with the fuel content of the ore itself and other purposes; and, similarly, in treating many iron ores, it has long been customary to introduce in addition to the ore flux and fuel, carbon (in excess of that necessary to supply the needed heat for melting) for deoxidizing, carburizlng and like purposes. The present invention is not concerned with the introduction of additions other than fuel which must be introduced to melt the particular material, but contemplates that other additions will be introduced into the material according to the particular character and appropriate treatment thereof, in any of the known ways. Contemplating that such additions will be introduced in known ways, assuited to the character of the particular ore, the present invention and the following claims are concerned with the development and application of heat from fuel introduced to effect the melting of the lower portion of a. piled mass of the material. Suggestions have been made that specially prepared substances and fluxes may be introduced into the hearth of iron furnaces with the blast at the twyers; In so far as such suggestions relate to such additions as have been mentioned, they do not conflict with the present invention, which may be practised with or Without them. In so far as such suggestions may relate to the development of heat from fuel introduced to effect the melting of the material, they have been rejected as impracticable, because they have not embraced the conditions essential to successful operation, which are supplied by the present invention. The present invention may be availed of in many differing forms, according to the particular material to' be treatedand the circumstances presented. It should be understood that many changes and modifications are contemplated and covered by the following claims 1. A process for use in smelting ores an the like, comprising arranging the material in a vertical piled mass upon a suitable bottom support and within a suitable shaft, providing suitable space for combustion by supplementing the interstices between the particles of the material by a space adjoining the lower portion of said mass, forcing into said adjoining space air under pressure carrying pulverized fuel and igniting the same therein, and forcing said ignited stream directly against and into the lower portion of the mass to effect the melting thereof.

2. A process for use in smelting ores and the'like, comprising arranging the material in a vertical piled mass upon a suitable bottom support and within a suitable shaft, providing suitable space for combustion by supplementing the interstices between the particles of the material by a space ad o1ning the lower portion of said mass, forcing into said adjoining space air under pressure carrying finely-divided coal and igniting the same therein, and forc ng said ignited stream directly against and into the lower portion of the mass to effect the melting thereof.

3. A process for use in smelting ores and the like, comprising arranging the material in a vertical 'piled mass upon a suitable bottom support and within a suitable shaft, providing within the lower portion of said shaft sufficient space (not occupied by the pieces of the material piled therein) for combustion to develop heat,'forcing into said space in a direction radial to the mass air under pressure carrying solid particles of fuel in quantity to develop suitable heat, and burning said fuel within the lower portion of the shaft to bring the lower portion of the mass of material to molten condition.

4. A process for use in smelting ores and the like, comprising arranging the material I in a vertical piled mass upon a suitable bottom support and within a suitable shaft, providin within the lower portion of said shaft su 'cient space (not occupied b the pieces of the material piled therein) for combustion to develop heat, forcing into said space in a direction radial to the mass air under pressure carryingsolid articles of coal in quantity to develop suitable heat, and burning said coal within the lower portion of the shaft to bring the lower portion of the mass of material to molten condition.

5. A process for use in smelting ores and the like, comprising establishing within a suitable shaft a piled column of material, providin within the lower portion of said shaft su cient space (not occupied by the particles of tl1e material) for the combustion of enough fuel to develop sufficient heat to bring the lower portion of the material to molten condition without permitting reverberatory action, forcing into such pace and into direct contact with the particles of the material air under pressure carrying enough finely-divided solid fuel to develop suitable heat, maintaining in said column sufficient material and supplying said air in sufficient quantities to maintain a substantial pressure of air in the space for com bustion, and burnin said supply of fuel in said pressure of alr within said space to bring the lower portion of said column to molten condition.

6. A- process for use in smelting ores and the like, comprising" establishing a piled mass of material, surrounding said mass with the Walls of a suitable chamber, pro

directly against and into the lower portion of the mass to bring the same to molten conin the lower portion of the furnace sufficient space (not occupied by the pieces of the charge) for the combustion of enough fuel to develop suitable heat, introducing into said space in a direction radial to the mass a suitable quantity of finely-divided solid fuel and air, and burning said fuel in said air in said combustion space to bring the lower portion of the material to molten condition.

8. In blast-furnace smelting of ores the process which comprises establishing and maintaining a descending column of ore and othermaterials in a suitable shaft and normally directing against the lower portion of such column a current of air carrying ignited powdered fuel in suspension in amount sufficient to maintain smelting conditions within such column.

9. An apparatus for smelting ores and the like, comprising, in combination. a shaft connected with a flue and provided with means for introducing the material at its top, a bottom for the shaft suitable for supporting a column of the material piled within the shaft and provided with means for conducting away the molten portion of the material, a space included within the shaft adjoining the lower portion of the column of the material when piled therein, a twyer entering said space and directed toward the axis of the shaft, said twyer being connected with a source of air under pressure and also with a source for supplying pulverized fuel, means for forcing air under pressure through said twyer, and means for feeding to said air finely-divided solid fuel to be carried by said air into said space and after ignition therein directly against and into the lower portion of the material.

10. In a blast furnace for smelting ores and the like, a restricted space within the vfurnace adjoining the lower portion of the into said space'and after ignition therein directly against and into the material in the furnace.

ULYSSES A. GARRED.