US3611543A - System for hot de-oiling and hot briquetting - Google Patents

Abstract

A SYSTEM FOR HOT DE-OILING AND HOT BRIQUETTING MATERIAL WHEREIN THE MATERIAL IS HEATED, TO BURN OFF OR VAPORIZE FOREIGN SUBSTANCES AND IS THEN TRANSPORTED TO A BRIQUETTNG MACHINE FOR FORMING OF THE MATERIAL INTO BIRQUETS. THE IMPROVEMENTS OF THE INVENTION RELATE TO A FURNACE CONSTRUCTION AND METHOD OF OPERATION FOR HEATING THE MATERIAL. THE FURNACE CONSTRUCTION INCLUDES A COMBUSTION AREA WITH MATERIAL BEING FED TO THE COMBUSTION AREA FROM A BOTTOM INLET. THE MATERIAL IS CARRIED THROUGH THE INLET BY MEANS OF AN AIR STREAM AND AN OUTLET IS DEFINED IN

THE COMBUSTION ZONE WHEREBY AFTER BURNING , THE MATERIALS WITHIN THE ZONE ARE DELIVERED TO BRIQUETTING EQUIPMENT.

Description

Oct. 12, 1971 J. E. MOORE 3,611,543

SYSTEM FOR HOT DE'OILING AND HOT BRIQUETTIN'G Original Filed April 15. 1968 2 SheetsSheot 1 CAST IRON BOR/A/GS n I u 12 i 5CREM OVEES/ZE STACK a A f4} \\3Z 015 FURNACE saunas/2 Harem/ 5 BYPASS Amousrrma MACH/NE 22 FINES SCREEN I BR/OUETTES INVfNm/P 6 022265 5. Moon: 1 w %1 M flffys Oct. 12, 1971 J. E. MOORE SYSTEM FOR HOT DE'OILING AND HOT BRIQUETTING Original Filed April 15. 1968 TABLE H5505)? CYCLONE 1 5524mm? Sheets-Sheen 2 mlwfm Mae/mm United States Patent US. Cl. 29-403 7 Claims ABSTRACT OF THE DISCLOSURE A system for hot de-oiling and hot briquetting material wherein the material is heated to burn off or vaporize foreign substances and is then transported to a briquetting machine for forming of the material into briquets. The improvements of the invention relate to a furnace construction and method of operation for heating the material. The furnace construction includes a combustion area with material being fed to the combustion area from a bottom inlet. The material is carried through the inlet by means of an air stream and an outlet is defined in the combustion zone whereby after burning, the materials within the zone are delivered to briquetting equipment.

This application is a division of copending application Ser. No. 721,474, filed Apr. 15, 1968, and now Pat. No. 3,497,190.

This invention relates to a system for hot de-oiling and hot briquetting. The invention is particularly concerned with the processing of materials such as crushed turnings, chips, borings, and other metal scrap, for example, those materials consumed in melting shops.

The briquetting of scrap materials such as turnings and borings has been recognized as a highly economical and efiicient procedure. Turnings and borings have a com position which makes them highly suitable for use in charging operations in a foundry. These materials are readily available at low cost and, to add to the efliciency, they are often produced in a machine shop near a melting shop.

The turnings and borings have certain drawbacks, however, due to the fact that they are very small dimensionally and are usually coated with oil and water. These characteristics make them highly undesirable as additives in a cupola or in an electric furnace.

By hot de-oiling and hot briquetting the turnings and borings, the drawbacks referred to can be overcome. The briquets produced are of satisfactory size and density so that the original size of the turnings and borings is of no consequence when briquets are formed for addition to a melting furnace. Similarly, the oil and water on the turnings and borings is vaporized off as a regular step in the briquetting procedure so that the briquetted product will be virtually free of any oil and water traces.

The presence of oil on the turnings and borings presents another distinct advantage during hot briquetting. Thus, the oil serves as a fuel which is consumed as the oil is removed. This provides an ideal means for controlling temperature and non-oxidizing conditions in the combustion zone of a furnace employed for removing the oil. The air-to-fuel ratio within the furnace can be maintained at a desired level to provide a temperature of desired magnitude.

The system of this invention is also designed to eliminate adverse conditions which can arise due to the burning of the oil. Specifically, excess oil vapors and smoke can cause highly undesirable air pollution, and afterburner means are provided for burning the excess oil to eliminate this problem. In addition, the discharge from the system can be scrubbed by suitable mechanisms to further reduce the introduction of contaminants into the arr.

It is a general object of this invention to provide improvements in hot briquetting and hot de-oiling, particularly with respect to improvements in furnace constructions employed for removing foreign substances such as oil and water from the surfaces of the materials and simultaneously preheating the materials for briquetting or other use.

It is a more particular object of this invention to provide a furnace construction of the type described which is relatively low in cost and which operates with a high degree of efficiency, dependability and economy.

It is a still further object of this invention to provide a furnace design which is particularly suitable for the treatment of discharge from the furnace for purposes of burning excess oil vapor and for avoiding the entrainment of dust in oif-gases whereby little or no dust is carried from the furnace to the afterburner, scrubber and/ or atmosphere.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a schematic illustration of a hot briquetting system of the type contemplated by this invention; and,

FIG. 2 is an illustration of the furnace construction of this invention.

The system of this invention is specifically designed for the processing of material such as turnings and borings. In accordance with prior practice, the turnings and borings are placed in a furnace construction for purposes of burning off foreign substances such as oil from the surfaces of the turnings and borings. The hot materials are then transported to a briquetting machine for forming into briquets or utilized for other purposes. Although the invention will be described with reference to the treatment of metal, other materials can also be advantageously handled in these systems. For example, ores which have a fuel associated with the material when it is introduced into the furnace can be treated in accordance with the principles to be described.

In prior constructions employed for heating of the turnings and borings, it was thought necessary to provide a carefully constructed furnace which included different zones characterized by distinct operations. Thus, a central zone of such furnaces provided a primary combustion zone into which material to be briquetted was introduced. Means were provided for blowing the material into the furnace to scatter the particles since this was thought necessary to provide sufficient heat transfer.

A supplemental heating zone equipped with burners was located beneath the primary zone. Rakes were provided for gradually moving the material so that the material would eventually drop through the two heating zones.

Above the primary zone, an afterburner was provided. By the introduction of air into this afterburner zone, unburned oil vapors would be burned in the afterburner thereby reducing contamination of the atmosphere. Rakes were utilized in this zone for returning settled dust which collected on the floor of the afterburner chamber.

The instant invention provides a system for accomplishing hot processing of metal pieces in a more economical and eflicient manner when compared with prior systems. The system can be utilized for purposes of heating of turnings and borings to the extent that these marerials can be briquetted for use as charge materials or otherwise processed.

The arrangement is particularly suitable for providing maximum production rates, minimum installation costs and minimum operational costs. A unique control of gas flow provides maximum efficiency, and the arrangement permits relatively low operating temperatures, and minimum entrainment of dust in the exhaust.

FIG. 1 comprises a schematic illustration of a system for hot briquetting. In this system, cast iron borings are transported, as shown at 10, to a sizing screen 12. The screen 12 removes over-sized material whereby the material fed to the furnace 14 and the product of the furnace will be of relatively uniform dimension.

The hot chips are delivered from the furnace through line 16 to a briquetting machine 18. The briquets produced by the briquetting machine are transported through a cooler 20 and are then passed across a screen 22. The fines comprising particles which are separate from the briquets are fed back as shown at 24 for re-cycling through the furnace. In the event that the discharge from the furnace is not to be briquetted, a by-pass 25 is provided in line 16.

A scrubber 26 is provided for collecting the gases issuing from the furnace through afterburner 28. A pump 30 withdraws the gases from the scrubber for passage through a stack 32 into the atmosphere.

FIG. 2 illustrates a system for heating of materials such as turnings and borings. This system includes a feed hopper 140 which may be provided with material from a screen such as shown at 12 in FIG. 1. A table feeding means 142 delivers the material in the hopper to passage 144 where the material falls downwardly into communication with passage 146. A relatively high velocity air stream is moving in the passage 146, and the material is entrained within this air stream and is carried upwardly into the combustion zone 148.

It will be noted that the passage 146 is relatively narrow; however, the cross section of the combustion zone gradually increases whereby the pressure exerted by the air stream on the chips and borings will be correspondingly reduced. This reduction in pressure will result in return movement of some of the material, particularly the coarser pieces, and a discharge chute 150 is provided for collecting this material. Furthermore, the recycling of hot chips ignites the new chips which are introduced An equilibrium condition will tend to be established since the build-up of material being fed in by the air stream will also tend to cause discharge of material through the chute 150. The passage 146 and combustion zone 148 may define an oval, rectangular or circular cross section, and the inlet for the chute 150 may extend substantially completely across the tapered side to provide for maximum collection of chips which have been exposed to the combustion zone.

A pressure detecting means of any suitable design may be inserted in the passage 146 as indicated at P in FIG. 2. The weight of the material above the pressure indicating means can thereby be measured, and the feed rate of material from the hopper can thereby be controlled.

A temperature detecting means may be provided at T in the outlet 147. This detecting means can be associated with a control for the air flow into the passage 146. Thus, as the temperature builds up, the air flow can be reduced to decrease the combustion rate.

The construction of FIG. 2 may also include a cyclone separator 152 which will receive the gas stream along with the finer particles. The cyclone separator is designed so that the finer particles will pile up at the bottom of the separator adjacent the door 154 which acts as a trickle valve. Ultimately, the finer particles will pass back into the combustion zone, and at least portions will be collected in the chute 150 for ultimate passage to the briquetting machine 156. Alternatively, these particles could be directed through line 157 into the briquetting machine.

An auxiliary burner 158 is attached to one side wall of the construction in the vicinity of the combustion zone. 75,

The auxiliary burner operates to begin combustion as the initial material is fed into the combustion zone. Once combustion has been initiated, the fuel provided by the oil on the materials will usually eliminate the need for any auxiliary burning apparatus, although the burner is available for this purpose. An afterburner is also preferably provided for receiving the discharge from stack 147.

In the system described, the aim is to provide a high furnace capacity in the sense that the tonnage per hour of production is high relative to the size of the furnace. Rates of 30 tons per hour are obtainable without dithculty. I

The high capacity is possibly due to the fact that the oil associated with the particles will ignite immediately adjacent the particle surfaces. This provides for high heat transfer, and thus rapid heating of the particles so that the particles can be moved through the constructions at a high rate.

The unit described can be readily provided with afterburner constructions, scrubbers, and other pollution control means. The ease with which these facilities can be applied is an extremely important feature from the standpoint of installation costs.

An additional benefit arises from the fact that a reducing atmosphere or an atmosphere low in oxidizing ingredients is provided in all instances. Thus, the air which is introduced into the combustion zone is controlled to provide only enough air to support combustion. The hot particles are thereafter only exposed to the combustion gases which contain little or no oxygen whereby oxidation of the particles can be virtually-eliminated. Excess air is only introduced in the afterburner zone of the various constructions.

It will be understood that various changes and modifications may. be made in the above described systems which provide the characteristics of this invention without departing from the spirit thereof.

I claim:

.1. In a system for heating material formed of a mass of small, individual metallic pieces carrying foreign substances at least part of which are combustible whereby the burning of said substances assists in the heating of the material, and for forming the hot metallic pieces into briquets, the improvement comprising a furnace construction for heating the material, said furnace construction including a combustion zone, at least one inlet opening adjacent the combustionzone and located at a level below at least a portion of the combustion zone, means for directing a stream of air through said inlet opening and into said combustion zone, means for feeding said material into said stream whereby said material is carried with the air through said inlet opening for movement of the material directly into the combustion zone, a first outlet defined by the furnace, said material then being moved upwardly in the combustion zone by said air stream and then falling downwardly to said first outlet, a second outlet defined by said furnace, the gases resulting from said combustion passing out of said furnace through said second outlet, and wherein hot pieces of material previously introduced into said combustion zone serve to ignite material newly introduced into the combustion zone, a briquetting machine, and including means connected to said construction for delivering said material from said first outlet directly to said briquetting machine for thereby forming briquets made up of large numbers of said pieces.

2. A system in accordance with claim 1 wherein said air stream contacts said-material at the bottom of said combustion zone and operates to drive said material upwardly and laterally through the combustion zone for burning of said foreign substances, said material then falling downwardly with said first outlet being located to the side of said inlet opening.

3. A system in accordance with claim 2 wherein said first outlet is defined adjacent. the bottom of said combustion zone.

4. A system in accordance with claim 3 wherein a relatively narrow passage is provided for the air stream contacting the material being fed to the combustion zone, and wherein said passage communicates with a relatively Wide furnace section whereby the pressure of the air stream on the materials is substantially reduced so that at least part of the material will move downwardly toward said first outlet.

5. A system in accordance with claim 4 including a separator attached to said furnace construction for receiving the air stream after passage through the combustion zone, said separator operating to remove solid particles contained in said air stream, and means for recovering said solid particles.

6. A method for heating a mass of small, individual metallic pieces in a furnace construction wherein the pieces carry foreign substances at least part of which are combustible whereby the burning of said substances assists in the heating of the pieces, the improvement comprising the steps of providing an air stream, contacting said pieces with said air stream whereby said pieces are entrained in said stream, continuously introducing said air and entrained pieces through inlet means located in a lower portion of the furnace construction directly into a combustion zone adjacent the inlet means whereby the combustible substances in the material are ignited by hot pieces previously introduced in the combustion zone, providing a first outlet for said pieces at a laterally spaced position, said air stream and entrained pieces moving upwardly and laterally through the combustion zone and at least a portion of said pieces then falling downwardly toward said first outlet, providing a second outlet for the combustion gases located in an upper portion of the construction, providing a briquetting machine in direct association with said first outlet, delivering hot pieces to said briquetting machine, and forming said hot pieces into briquets made up of a plurality of such pieces.

7. A method in accordance with claim 6 wherein the amount of air introduced is controlled to provide approximately the amount necessary to support combustion whereby oxidizing conditions in the area of the combustion zone are minimal.

References Cited UNITED STATES PATENTS 2,302,980 11/1942 Stern 29-403 UX 2,720,710" 10/ 1955 Erisman 34-28 2,925,821 2/1960 iMacDonald 110-14 X 3,125,437 3/1964 Moore et al. -3 3,352,605 11/1967 McCandless -104 X 3,412,985 11/1968 Perry et al. 110-18 3,450,529 6/1969 MacDonald 18-9 X JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner U.S. Cl. X.R.

29-200 D, DIG 7; 110-104; 134-2; 266-33 S

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