US3616768A - Apparatus for the destruction of refuse - Google Patents

Abstract

IN A NOVEL APPARATUS USEFUL FOR THE INCINERATION OF REFUSE MATERIAL COMPRISING ADJACENT FIRST AND SECOND ZONES IN WHICH THE FIRST ZONE IS A HEAT GENERATING ZONE IN WHICH ELECTRIC HEATING MEANS ARE EMPLOYED TO HEAT A MASS OF MATERIAL DISPOSED THEREIN THEREBY PROVIDING A HIGH TEMPERATURE ENVIRONMENT FOR A SECOND ZONE COMMUNICATING THEREWITH AND IN WHICH THE SECOND ZONE IS THE INCINERATION ZONE AND COMPRISES MEANS TO INTRODUCE REFUSE MATERIAL THERETO AND MEANS TO INTRODUCE FLUIDS THERETO WHICH PROMOTE AND/OR SUPPORT THE INCINERATION OF THE REFUSE MATERIAL, THE IMPROVEMENT WHICH COMPRISES AUXILIARY HEATING MEANS FOR PROVIDING ADDITIONAL HEAT WITHIN THE SECOND ZONE FOR LIMITING THE AMOUNT OF OXYGEN REACHING THE FIRST ZONE, FOR PREHEATING THE OXYGEN AND FOR PREVENTING SLAG BUILD-UP ON THE WALLS OF THE SECOND ZONE.

Description

1971 K. J. SOUTHWICK APPARATUS FOR THE DESTRUCTION OF REFUSE 2 Sheets-Sheet 1 Filed June 16, 1970 INVENTOR Fl I KENNETH J. SOUTHWICK ATTORNEY 2, 1971 K. J. SOUTHWICK 3,616,768

APPARATUS FOR THE DESTRUCTION 0F REFUSE Filed June 16. 1970 2 Sheets-Shoot 2 INVENTOR KENNETH J. SOUTHWICK BY I T V K. 9% a 9 MA ATTORNEY United States Patent US. Cl. 1108 E 5 Claims ABSTRACT OF THE DISCLOSURE In a novel apparatus useful for the incineration of refuse material comprising adjacent first and second zones in which the first zone is a heat generating zone in which electrical heating means are employed to heat a mass of material disposed therein thereby providing a high temperature environment for a second zone communicating therewith and in which the second zone is the incineration zone and comprises means to introduce refuse material thereto and means to introduce fluids thereto which promote and/or support the incineration of the refuse material, the improvement which comprises auxiliary heating means for providing additional heat within the second zone for limiting the amount of oxygen reaching the first zone, for preheating the oxygen and for preventing slag build-up on the walls of the second zone.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of Ser. No. 786,685 filed Dec. 24, 1968, now Pat. No. 3,527,178 and Ser. No. 44,788 filed June 9, 1970 by Kenneth J. Southwick.

BACKGROUND OF THE INVENTION Part 1.-Field of the invention This invention relates to the incineration of refuse material. More precisely, the invention disclosed herein relates to a novel incinerator which can efliciently incinerate material such as garbage, paper, cans, bottles and the like.

Part 2.Description of the prior art The elimination or destruction of refuse is an outstanding problem of critical proportions. Incinerators are known and routinely employed in the destruction of such refuse. However, known incinerators leave much to be desired in both their operation and overall efficiency. For example, small scale incinerators such as those employed in the home can dispose of such refuse as paper or the like but cannot conveniently dispose of such refuse ma terial as bottles and cans or the like. Moreover, large scale incinerators such as those employed to destroy refuse collected from municipalities leave much to be desired. For example, incinerators employed in such applications require supplemental fuels which limit the heat available for incineration of the refuse material and also contribute to the increased pollution of the air. Moreover, many present incinerators are not truly capable of continuous operation over extended times. Instead, their operation time is somewhat limited by the accumulation of the incinerated residue which must periodically be discharged therefrom by way of grates or the like thereby interrupting continuous operation. It is to these and related problems outstanding in the art of incineration in general to which the present invention is addressed to provide a novel solution therefor.

Patented Nov. 2., 1971 In accordance with the present invention, an improvement in novel apparatus for incineration is presented. Essentially, the basic apparatus is an integration of structural elements combined in a fashion to provide two adjacent zones. In the first zone which functions primarily as a heat generating zone, a mass of material is heated by electrical means to provide heat for the incineration of refuse material charged to the second zone. The mass of material heated in the first zone can be, for example, a pure metal, metal alloy, metal refuse or other electrically conducting material, if desired. The electrical heating means heats the mass to its melting temperature and maintains the mass in a semi-molten or preferably molten state. The level of the melted mass approximately defines the boundary between the zones. The heat generating zone provides a high temperature environment in the second zone wherein the major portion of incineration occurs. The second zone is provided with means to charge refuse material thereto and means to introduce a fluid thereto. The fluid which can be air or like fluids provides support for and/or promotes incineration of the material charged into the zone. The products of incineration are continually removed from the incinerator during the operation. The manner by which the product is removed depends primarily on the nature of the material incinerated and the nature of the product resulting from substantially complete incineration thereof. For example, easily combustible material such as paper or the like can be rapidly incinerated and converted to relatively light products upon incineration. These products are easily discharged from the incinerator by entrainment with gaseous products emerging therefrom. The products of less readily combustible materials such as glass or metal which are produced in the present apparatus are collected at the boundary between the first and second zones which is approximately defined by the level of the melted material in the first zone. At this boundary, the products are heated to a molten state or semi-molten state and means are provided to remove the products. For example, overflow spouts or the like are positioned at or near the boundary to remove excess melted material accumulated there to thereby maintain the material at a substantially constant level throughout the operation.

The present invention is an improvement on the basic apparatus described above. It has been found that under certain conditions, i.e., where the products which undergo melting in zone one comprise a large percentage of the refuse, there is a tendency to form oxides at the boundary between the zones. These oxides may form a crust over the surface of the melted mass and inhibit the smooth operation of the incinerator. Much of this oxide formation can be prevented by promoting more complete combustion above the mass surface in zone two consuming the major portion of the combustion supporting fluid, usually air containing oxygen before it is allowed to reach the vicinity of the surface. This is accomplished by the addition of auxiliary heating means along at least a portion of the length of zone two. Placement of these heating means in such a way as to heat the incoming air further enhances the combustion process above the surface and further serves to limit the amount of oxygen available for oxide formation at the surface.

In addition, the employment of auxiliary heating means as described above results in the further advantage of preventing slag build-up on the walls of the incinerator above the level of the melted mass. As non-combustible refuse falls into the melted mass in zone one, a certain amount of slag splashing will occur which will, without the use of the invention, result in the gradual build-up of a layer of slag on the colder Walls of zone two. The layer may also provide a binder prior to complete cooling for newly introduced refuse as it contacts the Zone two walls in its descent. Thus, the combination of molten slag and fresh refuse striking the cold wall 'will produce a build-up of crust which, as is obvious, will eventually inhibit the operation of the incinerator. By heating the walls with the auxiliary apparatus as described, it has been found that this build-up may be eliminated.

Many advantages can be derived from the practice of the present incinerator. Chief among these is the reduced pollution of the atmosphere. Unlike present incinerators, the apparatus of the present invention does not require the use of secondary fuels such as coal, coke, gas or the like. Instead, the refuse material is employed as the primary fuel and thus the amount of pollution is limited to that created by the incineration of the refuse material alone. Also in present incinerators employing secondary fuels, the heat available is primarily limited by the fuel employed. Accordingly, the operating temperatures cannot be conveniently varied. In contrast thereto, the present apparatus permits variations in temperatures. For example, if the only refuse material involved should be easily combustible such as paper or the like, a low melting metal or alloy can be employed in the first zone and can be heated by electrical induction heating means of a preselected frequency. Accordingly, the incineration temperature can be varied by selecting the appropriate combination of metal and power imput in the first zone thereby permitting close adjustment and control between the energy and/or heat required to incinerate the particular refuse material involved. Another advantage in the present invention is that incineration can be conducted in a substantially continuous fashion over extended periods of time since the incineration products are continuously removed therefrom during operation. Other advantages and benefits involved in the practice of the present incinerator will be set forth in detail hereinafter or will be apparent to those skilled in the art from the following detailed description in conjunction with the accompanying drawings.

DESCRIPTION OF THE FIGURES FIG. 1 is a cut-away 'view of an incinerator employing one embodiment of the invention;

FIG. 2 is a sectional view of FIG. 1; and

FIG. 3 is an additional sectional view of FIG. 1..

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown an incinerator solidly supported on supports 5. The incinerator has two adjacent zones; zone 1 and 2. Zone -1 is defined by a periphery wall 4 which is preferably fabricated of an electrically non-conductive refractory material but can be fabricated of an electrically conductive material depending on the type of electrical heating means involved. In turn, wall 4 is oftentimes bounded by another reinforcing wall 8 also preferably fabricated of suitable refractory material. The lower boundary of zone 1 is defined by a layer 6 of a non-conductive heat resistant material preferably in particulate form such as foundry sand. In the operation of the incinerator, a material such as a relatively pure metal and/or metal alloy is charged to zone 1. The charged material is then heated preferably to above its melting point by electrical heating means 10 which is a water cooled, high frequency induction heating coil wrapped about a substantial portion of zone 1 powered by a source as shown. The upper level of the heated mass of material approximately defines the boundary between zones 1 and 2 and is indicated by AA of FIG. 1. Electrical insulation means 12 are employed to isolate electrical heating means 10 from any metal components of the incinerator which may be located near induction heating means 10. Grounding means (not shown) can also be employed in manners known to the art.

Direct high frequency induction heating means illustrated in FIG. 1 are preferred in heating the mass of material disposed in zone 1. However, it is to be understood that other electrical induction heating means such as indirect and semi-direct electrical induction heating means as well as dielectric heating means can be employed. The manners, methods and arrangements by which such means can be employed to heat the mass of material in zone 1 are known to those skilled in the art and they need not be discussed in detail. Also the frequencies employed will depend upon such factors as the nature of the material to be incinerated, the size of the incinerator and the particular metal heated in zone 1. The frequencies normally employed are those between about 60-960 c.p.s. which can be obtained by rotating generators or converters or the like. If higher frequencies are employed, e.g. from about 96010,000 c.p.s. or even higher, motor generator sets and converters can be employed as suitable sources of power. Oftentimes, two separate frequencies with separate induction coils can be employed to obtain maximum efliciency at minimum cost.

Oftentimes means to completely purge or discharge the heated material from zone 1 are desirable in incinerators of the present invention. One arrangement of such means is shown in FIG. 1 in which bottom plate 17 having plug 14 in the central regions thereof is supported by supports 19. Plug 14 can be removed from plate 17 by actuating lever 16. Layer 6 which is normally a heat resistant and electrically non-conducting particulate material such as foundry sand can be drained from zone 1 together with the heated material. Alternately, supports 19 can be withdrawn thereby permitting the removal of plate 17 and discharge of the mass in zone 1. Further, spout 13 heated by electrical coil 9 blocked by plug 11 may be used. It is to be understood that the means to purge or discharge the heated mass from zone I normally need not be employed except in an extreme emergency or for replacing refractory material in zone 1. During normal operation the mass need not be removed. For example, if the operation is terminated for any particular interval of time, the operation can be resumed by merely reheating the mass in zone 1 to provide sufficient heat for the incineration of material charged to zone 2.

Referring now to the improvement which comprises the invention, zone 2 defines the incinerator chamber and comprises in this embodiment at its lower level a periphery of electrically conducting refractory material 20, a graphite clay mixture for example, which is normally bounded by an insulating or reinforcing wall 22 preferably fabricated of non-conducting refractory. At the lower portion of zone 2, a series of tuyeres 26 are provided to introduce a combustion supporting fluid usually air to zone 2 to promote and/or maintain the incineration of refuse material. The fluid is introduced to zone 2 such as from wind box 24 by way of tuyeres 26. As illustrated in FIG. 1, three series of tuyeres 26 are arranged concentrically one above the other about zone 2. The number of series and the concentric arrangement and the shape of the individual tuyeres can vary and is dependent primarily upon such factors as the nature of the material incinerated and the particular fluid employed. Accordingly, modifications of these features can be employed to introduce suflicient fluid to promote and/or maintain incineration of the refuse material delivered to zone 2. For example, as illustrated in FIG. 2, tuyeres 26 are positioned approximately equidistant about zone 2 and arranged to direct fluid to the center of zone 2 along a line approximately parallel to the horizontal axis of zone 2. The positioning and arrangement shown can be varied. For example, tuyeres 26 can be arranged so as to introduce the fluid in a tangential fashion to zone 2 or to direct some or all of the fluid downward toward zone 1 or substantially upward through zone 2.

Auxiliary heating means 29, a hollow water cooled electrical induction coil for example, are shown encased in insulating material 21 surrounding the periphery of zone 2. Upon application of power to coil 29 from a source as shown secondary currents suflicient to heat the lower portion of the inner wall of zone 2 will be induced in the claygraphite refractory material comprising wall 20. The frequencies and parameters of the power source are similar to those used for the heating means in zone one described above.

As shown in the drawing, the location of the auxiliary heating system additionally serves to heat the incoming fluid which heating may further be enhanced by the empolyment of heat conducting sleeves 23 in tuyeres 26 in combination with wall 20. It will be understood that other methods of supplying additional heat to the portion of zone two directly above the heated mass may be employed. Conventional combustion systems, gas jets for example, may be used. Optionally plasma generating techniques have been found to be suitable.

As described above, the addition of auxiliary heating means in zone two facilitates the complete use of incoming oxygen for combustion within the incinerator, resulting in the curtailment of oxide formation on the top of the melted mass in zone one.

Additionally, the heated walls of zone two prevent buildup or accumulation of slag particularly in the area directly above the heated mass. Section 20A of wall 20 slopes inwardly to present a non-horizontal heated surface in the region most likely to come in contact with slag splashed upwardly by falling non-combustible refuse, bottles and items composed of heavy metal for example. Heating of that portion of the wall in particular decreases the temperature differential between the surface and the splashed slag preventing rapid cooling on contact and the likelihood of sticking. As will be seen, refuse striking that area from above would similarly tend to adhere if a slag buildup were allowed to occur.

As described above, the fluid is introduced to zone 2 to promote and/or maintain the incineration of refuse material delivered thereto. Normally, air or oxygen-enriched air is the fluid employed. However, other fluids can be employed sometimes alone or in combination with others. These can be combustible in nature such as the various lower boiling hydrocarbons or diverse other hydrocarbons normally employed as fuels. Also normally non-combustible fluids such as water vapor can be employed especially when high temperatures are generated within the incinerator chamber. Under such conditions the water 'vapor or like fluid can be broken down into its elemental components providing additional heat for incineration. Inert gases such as nitrogen and argon or the like which can ionize under conditions of high temperatures to generate heat can oftentimes be advantageously employed. Normally the fluid is introduced to zone 2 under somewhat higher than atmospheric pressure to promote agitation of the refuse material delivered to zone 2 thereby promoting rapid and eflicient incineration. Also by employing high pressures which can be alternately or selectively regulated, removal of the products of incineration is enhanced. One arrangement of providing high agitation and eflicient incineration involves a series of tuyeres arranged one above the other concentrically about the periphery of zone 2 with each series of tuyeres being connected to fluid sources under diflerent pressures.

Chute 28 provides means to introduce the refuse material into the incineration zone 2. As illustrated in FIG. 1, chute 28 is arranged to direct the refuse material to that portion of zone 2 opposite slag spouts 30, e.g., to that portion of wall 4 bounded by MM of FIG. 3. This arrangement of chute 28 is preferable but as will be apparent from the further description, other arrangements of chute 28 can be employed. The refuse material delivered into zone 2 can include easily combustible material such as paper, leaves and garbage or the like as well as materials which are not normally readily combustible such as materials of metal (cans) or of glass (bottles). Accordingly, the nature of the refuse material will normally determine the area in zone 2 where the major incineration of the material occurs. For example, when temperatures above 2000 F. are generated in zone 2 of FIG. 1, easily combustible material will undergo substantially complete incineration oftentimes almost immediately after being introduced to zone 2, e.g., well above the junction of zones 1 and 2 as indicated by line AA of FIG. 1. Moreover, the major portion of the products of the incineration of such materials are readily removed from zone 2 by the fluid flow therethrough.

The incineration of materials which are not readily combustible or which form incineration products of high density will normally occur closer to the junction of zones 1 and 2. Indeed in some instances, complete incineration of,materials such as cans and bottles or the like will occur after the material has contacted the molten mass in zone 1. .The products of materials which undergo incineration at or near the boundary of zones 1 and 2 are removed from the incineration apparatus by way of means to maintain the boundary substantially constant which are shown as slag spouts 30. As illustrated, slag spout(s) 30 are located below tuyeres 26 and arranged so as to maintain the level of the melted mass of materials heated in zone 1 substantially constant. The removal of the products of incineration by way of slag spout(s) 30 can be enhanced by assuring a difference in the density of the products and the material heated in zone 1. Also convection currents can be created in the mass of melted material in zone 1 to enhance removal of the products. For example, when high temperatures are employed, the heated material in zone 1 can resemble a boiling mass of molten lava. Since products removed by way of slag spout(s) 30 are normally in a molten or semi-molten state, heating means are usually provided for slag spout(s) 30 to assure efficient discharge to products therethrough. For example, induction heating means 32 is shown in FIG. 1 as a suitable heating means. Obviously, slag spout(s) 30 must be fabricated of a suitable heat resistant material.

Many advantages of the apparatus discussed above will be apparent to those skilled in the art. For example, the temperatures obtained in the incineration zone can be varied over a wide range by controlling the power imput. Although high temperatures are preferred, e.g., temperatures above about 2000 F., low temperatures can be realized by employing low melting metals in the heat generating zone (zone 1). Accordingly, incinerators of the present invention present features which permit close adjustment and control over such operating parameters as energy imput and heat produced. These features permit design of large scale incinerators as well as small scale units which can be employed efiiciently in remote areas for incineration of specific refuse. Still another advantage of the present apparatus is the reduced volume of the products of incineration. Even the less readily combustible refuse material undergoes substantially complete incineration and is removed or extruded from the apparatus in a substantially molten state. The molten material can be molded into convenient shapes and disposed of in this form. Alternatively, the molten material can be quenched, pelletized or ground up and employed as an inert filler useful in the construction of roads and like structures. Perhaps the most outstanding advantage of the apparatus is the continuous manner in which it can operate. This is in marked contrast to present incinerators which must be periodically shut down at frequent intervals to remove products of incineration therefrom.

Many modifications of features of the apparatus described for the purpose of illustrating the invention can be employed without departing from the spirit and scope of the invention defined in the appended claims. For example, direct induction heating means, indirect induction and semi-direct induction heating means or dielectric heating means can be employed for heating slag spout(s) 30. Also, various equipment normally employed with present incinerators can be associated with the apparatus of the present invention. Such equipment includes precipitators and filters or like equipment normally employed to reduce pollution. Afterburners can also be employed as well as energy recovery and energy conversions means such as to generate electricity which can be utilized in the operations involved. The manners and methods of integrating such elements with the present invention need not be discussed in detail since such manners and methods are well known to those skilled in the art to which the present invention pertains.

Having described my invention as well as manners of practicing same and preferred embodiments thereof, what I claim as new and desire to secure by U.S. Letters Patent is as follows:

1. In an incinerator comprising adjacent first and second zones,

said first zone defining a heat generating zone and comprising a periphery wall of refractory material, electrical heating means operationally communicating with said zone and means to retain a mass of material in said zone to be heated by said electric heating means whereupon the upper level of said heated mass approximately defines the boundary between said first and second zone;

said second zone defining primarily an incineration zone and comprising a periphery wall of refractory material, means to introduce an incineratable material to said zone, means to introduce a fluid to said zone which in combination with heat generated in said first Zone can cause incineration of material delivered to said second zone and means to remove molten products produced in said incinerator;

the improvement which comprises:

auxiliary heating means for supplying additional heat to at least a portion of said second zone, said auxiliary heating means located on the periphery of said second zone.

2. The apparatus of claim 1 wherein said auxiliary heating means comprises an electrical induction heating coil and the inner periphery of said second zone comprises an electrical conducting material.

3. The apparatus of claim 1 wherein a portion of said auxiliary heating means is positioned to heat said combustion supporting fluid prior to introduction into said second zone.

4. The apparatus of claim 2 wherein said electrical conducting material is comprised at least in part of carbon.

5. The apparatus of claim 4 wherein said electrical conducting material is comprised at least in part of clay.

References Cited UNITED STATES PATENTS 3,344,758 10/1967 Wotschke 1l018 3,417,717 12/1968 Jacobovici 18 R 3,527,178 9/1970 Southwick 110-8 E KENNETH W. SPRAGUE, Primary Examiner U.S. Cl. X.R. 110-18 E

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