US3744438A

US3744438A - Incinerating

Info

Publication number: US3744438A
Application number: US00177317A
Authority: US
Inventors: K Southwick
Original assignee: PYRO MAGNETICS CORP
Current assignee: PYRO-MAGNETICS Corp; PYRO MAGNETICS CORP
Priority date: 1968-12-24
Filing date: 1971-09-02
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10

Abstract

Incinerating refuse material by providing adjacent first and second zones, the first zone being a heat generating zone in which a mass of material is heated to provide a high temperature environment, and the second zone being an incineration zone communicating with the first zone into which refuse material and fluids which promote and/or support the incineration of the refuse material are introduced.

Description

United States Patent 1 1 i,

Southwick July 10, 1973 INCINERATING [56] References Cited [75] lnventor: Kenneth J. Southwick, Quincy, UNITED STATES PATENTS Mass- 3,481,290 12/1969 Wunderley. 110/8 I731 Assign Pym-Magnetics Corporation, 31321332 35133? EZLZ'ESZZIETII 1.0/18 Needham Mass- 2,537,467 1/1951 1(0mline.... 110/8 22 Filed: Sept. 2 1971 3,417,717 12/1968 J acobovici .11 10/7 PP 177,317 Primary ExaminerKenneth W. Sprague Related US. Application Data AtmmeY"-1ameS p [63] Continuation-impart of Ser. Nos. 44,788, June 16,

1970, Pat. N0. 3,616,767, and Ser. NO. 46,694, June ABSTRACT 1970, t- No. 3,616,768, and Ser. No. 53.416, lncinerating refuse material by providing adjacent first J 1 1648,6291 each a and second zones, the first zone being a heat generating igg g z' 'f gg12g zone in which a mass of material is heated to provide a a high temperature environment, and the second zone being an incineration zone communicating with the g 110/ 8 g first zone into which refuse material and fluidswhich [58] Field of Search 110/7, 8 R, s c, g i /$235223 mcmeratw the refuse 110/8 E, 10,18 R, 18 E i p 27 Claims, 5 Drawing Figures POWER SOURCE FIG. I

PAIENIEB HL 3.744.438

sum 2 0F 3 GAS SOURCE SUPPORTING FLUID SOURCE COMBUSTION SUPPORTING FLUID SOURCE FIGB Pmmcuw 3.744.438

SHEET 3 0F 3 POWER SOURCE POWER SOURCE FIGS INCINERATING CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of pending applications Ser. Nos. 44,788 and 46,694, both filed June 16, 1970 and now, respectively, U.S. Pat. Nos. 3,616,767 and 3,616,768, both issued Nov. 11, 1971; and Ser. No. 53,416, filed July 9, 1970 and now U.S. Pat. No. 3,648,629, issued Mar. 22, 1972, which applications are themselves continuations-in-part of application Ser. No. 786,685, filed Dec. 24, 1968, and now U.S. Pat. No. 3,527,178, issued Sept. 8, 1970.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the incineration of diverse refuse materials such as garbage, paper, cans, bottles and the like.

2. Description of the Prior Art The elimination or description of refuse is an outstanding problem of critical proportions. The known incinerators now routinely employed 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 soft refuse as paper or the like but cannot conveniently dispose of hard refuse material such as bottles and cans. Large scale incinerators, such as those employed to destroy refuse collected from municipalities, require supplemental fuels, often of low grades, 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 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.

SUMMARY OF THE INVENTION It is the purpose of this invention to present many improvements in incineration. One primary object is to provide a dual zone system wherein the lower zone, which functions primarily as a heat generating zone, is charged with an essentially non-combustible base mass which is heated to molten or semi-molten temperatures by, for example, combustion (i.e., fuel burning) or electrical (resistance or induction) heating means. The mass of material heated in the lower zone can be any material rendered molten or semi-molten at the temperatures supplied by the heating means. When induction heating means are used, the mass'is an electrically conducting material, such as a pure metal, a metal alloy, or metal refuse, and the use of all secondary fuels is eliminated.

The 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 lower heat generating zone and the upper second zone wherein the major portion of incineration occurs. The heated mass provides a high temperature environment in the second zone and, additionally, provides a bath which absorbs and melts non-combustible refuse. The

products of these less readily combustible materials, such as glass or metal, collect at the top level of the melted material, which approximately is at the boundary between the first and second zones, where they are heated to a molten state or semi-molten state and from where they may easily be removed.

Many advantages can be derived from the use of the molten mass. One of these is the reduced pollution of the atmosphere. Use of the mass eliminates the need for combustible secondary fuels such as coal, coke, gas or the like, used in the present incinerators. 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. Further, unlike present incinerators employing secondary fuels in which the heat available is primarily limited by the fuel employed, the energy input into the mass, the operating temperature of the mass, and heat produced and other operating parameters of the incinerator conveniently and efficiently may be varied. For example,

if the only-refuse material involved should be easilycombustible 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 preselected frequency. Accordingly, the incineration temperature can be varied by selecting the appropriate combination of metal and power input in the first zone thereby permitting close adjustment and control between the energy and/or heat required to incinerate the particular refuse material involved. Input energy to heat the mass can further be conserved, and incineration efficiency increased, by adjusting the size of the mass to the minimum needed for a particular operation. Thus the far larger mass needed in an operation I in which a large amount of refuse, for example an automobile, is incinerated need not retained and heated for a smaller operation. 1

The refuse material and a fluid which can be air or a like fluid which provides support for and/or promotes incineration of the refuse material, are charged into the second zone. The residue products of the device are continually removed during operation. The manner by which the product is removed depends primarily on the nature of the refuse material and the nature of the product resulting therefrom. For example, easily combustible material, i.e., soft refuse such as paper or the like will be rapidly burned and converted to gas and ash incineration products. The gases and some ash are easily discharged from the device by entrainment with gaseous products emerging therefrom. The ash may be screen filtered to prevent pollution of the atmosphere and/or recycled through the system for reburning. Heavier ash and less readily or non-combustible materials such as glass or metal which are introduced into the present apparatus, as previously mentioned, collect at the'boundary between the first and second zones where they are heated to a molten state or semi-molten state and combine with or float on the melted material.

It will be apparent that another major feature of this invention is substantial reduction in the volume of the products of incineration, as even less readily combustible refuse materials undergo substantially complete incineration and may be removed or extruded from the incineration in a substantially molten state. The molten material can be molded into convenient shapes and disposed of in this form, or it can be quenched, pelletized or ground up and employed as an inert filler useful in the construction of roads and like structures.

When these products 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. In one aspect of the present invention, any crusts which form may be removed by draining a portion of the mass under and supporting the crust, causing it to collapse and fragment. In another aspect, the crusts may be removed by melting with electric arc electrodes introduced through zone two into a position closely adjacent the crust in which the electric are between electrodes will melt any slag build-up and permit the slag to be removed from the incinerator in a molten state.

The use of such arc electrodes further reduces oxid formation, and thus crusting, by enhancing the combustion of the combustion supporting fluid, usually aircontaining oxygen, and thereby limiting the amount of oxygen available for oxide formation at the mass surface. Even more complete combustion may be promoted, and oxide formation substantially prevented, by providing auxiliary heating means along at least a por tion of the length of zone two in position for heating the incoming air.

The employment of such auxiliary heating means to heat the walls of zone two has the further advantage of preventing slag build-up on the walls above the level of the melted mass. As non-combustible refuse falls into the melted mass in zone one, a certain amount of slag will splash onto the walls of zone two. Also, some newly introduced refuse will contact the zone two walls in its descent. By heating the walls, it has been found that the build-up on the walls of the combustion of molten splashed slag and fresh refuse bound thereto (which would eventually inhibit the operation of the incinerator) may be eliminated.

Other features of the present invention include overflow spouts or the like 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; additional removal spouts or the like located in a plurality of positions along the vertical axis of the incinerator to remove excess melted material to a desired level; and sensing means to register the level of molten material and activating means to open or close the spouts are employed to draw off a sufficient amount of material to maintain the desired level. This control insures 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. Further, if a large amount of ash or non-conducting material has reduced the heating or electrical conducting capability of the basic mass, the material may be drained out to the extent required by activating a lower spout and the incinerator recharged with fresh material.

Other objects, features and advantages of the present incinerator will be apparent from the following detailed description of preferred embodiments, thereof, taken in conjunction with the accompanying drawings.

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

FIG. 2 is a sectional view of the incinerator of FIG.

FIGS. 3 and 4 are cut-away views of incinerators employing other embodimentsof the invention; and

FIG. 5 is a sectional view of the incinerator of FIG; 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2, there is shown an incinerator, generally designated 3, solidly supported on supports 7. The incinerator has two adjacent zones; zone 1 and 2.Zone 1 is defined by a periphery wall 4 of an electrically non-conductive refractory material, bounded by another reinforcing wall. 8 also preferably fabricated of suitable refractory material. Wall 4 may be fabricated of an electrically conductive material, depending on the type of electrical heating means involved. The lower boundary of zone 1 is defined by a layer of 6 of a non-conductive heat resistant material preferably in particulate form such as foundry sand. A relatively pure metal and/or metal alloy is charged to zone 1, and is heated to above its melting point by a water cooled, high frequency inductor heating coil 10 wrapped about a substantial portion of zone 1 and powered by a source as shown. The upper level A of the heated mass of material approximately defines the boundary between

zones

1 and 2. Coil 10 is embedded in electrical insulation 12 to isolate it from any metal components of the incinerator which may be located near the induction coil 10. Grounding means (not shown) can also be employed in manners known to the art. The manners, methods and arrangements by which coil 10 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. 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 mass heated in zone 1. The frequencies normally employed are those between about 960 cps which can be obtained by rotating generators or converters of the like. If higher frequencies are employed, e.g., from about 960 10,000 cps 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 efficiency at minimum cost.

The direct high frequency induction heating coil illustrated in FIG. 1 is 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.

Indirect heating of the mass is useful when, because of the addition of non-conducting materials, i.e., glass, thereto, during incinerating operations, the mass becomes insufficiently electrically conductive to support direct induction heating. For such heating, interior wall 4 is made of graphite or a graphite clay mixture, this graphite wall is he'ated'by induction, and the mass is heated indirectly by conduction.

Semi-direct heating may be employed when a normally non-conducting wall, i.e., a clay graphite wall becomes conductive at temperature higher than ambient. In this case, the the mass itself is sufficiently conductive to gain temperature by direct induction heating. Conduction heating of the wall follows allowing a rise in temperature providing conductivity sufficient to allow additional wall heating by the indirect method.

For completely purging or discharging the heated mass from zone 1, a closure plate 17, having plug 14 in the center thereof and supported by supports 19 is provided, at the bottom of zone 1. Plug 14 can be removed from plate 17 by actuating lever 16. Layer 6 which is normally a heat resistant and electrically nonconducting particulate material such as foundry sand can be drained from zone 1 together with the heated material. Alternately, the mass may be discharged by removing supports 19, thus permitting the removal of plate 17. It is to be understood that the heated mass normally need only be purged or discharged from zone 1 except in an extreme emergency or for replacing refractory material in zone 1. During normal operation the mass need not be removed. If the incinerating operation is terminated for any particular interval of time, incineration can be resumed by merely reheating the mass in zone 1 to provide sufficient heat for the incineration of material charged to zone 2.

Zone2 defines the incineration chamber and comprises -in the illustrated 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 wind box 24 and a series of tuyeres 26 are provided for introducing a combustion supporting fluid to zone 2 to promote and/or maintain the incineration of refuse material. As shown, fluid at somewhat higher than atmospheric pressure is forced from wind box 24 through tuyeres 26 and into zone 2. As illustrated in FIG. 1, three tuyere series, each of 8 circumferentially-spaced tuyere 26, are arranged concentrically one above the other about zone 2. The tuyeres of each series 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 flow of fluid supports incineration, and additionally agitates the refuse material delivered to zone 2, thereby promoting rapid and efficient incineration. The number of series, the particular 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, the positioning and other features of the arrangement shown can be varied as desired to provide sufficient fluid to promote and/or maintain incineration of the refuse material delivered to zone 2. For example, tuyeres 26 could be arranged so as to direct fluid in a tangential fashion to zone 2 and angularly downwardly toward zone 1 or upwardly through zone 2. When high pressures, which can be alternately or selectively regulated and enhances removal of the products of incineration, are employed, another affected arrangement involves a series of tuyeres arranged one above the other concentrically about the periphery zone 2 with each series of tuyeres being connected to fluid sources under different pressures.

Similarly, the type of fluid may itself vary. 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 chambersUnder 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.

Auxiliary heating means, comprising a hollow water cooled electrical induction coil 29 encased in insulating material 21, is provided surrounding the periphery of zone 2. Upon application of power to coil 29, from a source as shown, secondary currents sufficient to heat the lower portion of the inner wall of zone 2 will be induced in the clay-graphite 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 drqwing, the location of the auxiliary heating coil additionally serves to heat the incoming fluid facilitating complete use of incoming oxygen for combustion within the incinerator and resulting in the curtailment of oxide formation on the top of the melted mass in zone one. This heating may further be enhanced by the employment of heat conducting sleeves '23 in tuyeres 26 in combination with wall 20. It will be tion systems, gas jets for example, may be used. Option-- ally plasma generating techniques have been found to be suitable. I

Heating the walls of zone two also prevents build-up 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 difl'erential 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 build-up were allowed to occur.

The refuse material is introduced into the incineration zone 2 through chute 28. 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. 2. This arrangement of chute 28 is preferable but as will be apparent from the further description, other arrangements of chute 28 can also be employed. The refuse material delivered into zone 2 can include easily combustible or soft-materials such as paper, leaves and garbage or the like as well as hard" materials which are not normally readily combustible such as materials of metal (cans) or of glass (bottles). 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 2,000F are generated in zone 2, easilycombustible 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 indicated by level A 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 insome 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 (i.e., the melted bottles, metal and other non-combustible refuse materials), together with the heavier ash products of combustible refuse materials, collect at the top of the mass as a slag. To maintain the boundary substantially constant and insure continuous incineration, these products are removed from theincineration apparatus by slag spouts 30. As illustrated, two spouts 30 are located below tuyeres 26 and arranged in the same plane about the periphery of the incinerator with their lower edges substantially coplanar with the level at which the top A of melted mass of materials heated in zone 1 is to be maintained. It will be understood that any combination of spouts may be employed in arrangements which are most convenient to the user.

Each spout 30 includes a gate 56A hingedly connected to the spout outer end and arranged for closing the outer end of the spout for preventing outflow therethrough. Sensing means are provided for detecting the level of the molten mass and gate 56A is responsive to the sensed level. As is obvious, a variety of sensing means may be used. For instance, a window may be inserted in the side of the incinerator and simple observation used to determine the level of the molten mass. Other means such as optical or radiation pyrometers may be used as well as thermo-couples.

In the illustrated embodiments, the sensing means comprises electrode 41 A imbedded in the lower incinerator wall and providing a common ground for electrodes 41 B and 41 C. Electrode 41 B is in substantially the same horizontal plane as the lower inner edge of spouts 30; electrode 41 C is slightly above the spout upper edge. Relay 42 is connected between electrodes 41 A and 41 B and relay 44 between electrodes 41 A and 41 C. Both relays are sufficiently sensitive to activate upon application of a current of the magnitude that will be found in the conductive mass as induced by coil 10. A signal switched by relay 42 is channeled to the reverse or closed terminal of hydraulic pump 46 through relay 48 and a signal switched by relay 44 is channeled to the forward or open terminal of the same motor. Additionally, a signal switched by relay 44 serves to deactivate relay 48. Power sources for the pump and the signals are not shown and may take any convenient form known in the art.

. In operation, the level of the mass rises contacting electrode 41 B. The pump is in reverse or closed condition and remains so while the level continues to rise. Relay 48 is normally closed.

When the level rises'to the position of electrode 41C, relay 44 is switched to deactivate or open relay 48 and to simultaneously engage the hydraulic pump. The pump operates hydraulic cylinder 50A through lines 52 and 54 opening door 56A allowing a portion of the mass to escape through exhaust spout'30. As the level falls, biasing current is removed from relay 44 halting the opening of door 56A and closing relay 48. The door will now begin to close since relay 42 will switch pump 46 to the reverse position through closed relay 48. As the door closes, some of the mass will continue to exhaust until the door is firmly closed. The pump is chosen to operate the door at a rate which will allow a sufficient amount of mass to escape to accomplish the purpose of the invention. In particular, it will be seen that it will be advantageous to operate the pump at a higher speed in the forward or opening mode than in the reverse or closing mode.

Two additional sets of removal spouts, designated 70,

80, respectively, are provided at levels below the upper boundary of the mass. As shown, spout is positioned approximately midway the height of the mass, and spout is located with its lower edge substantially coplanar with the lower boundary (defined by the top of layer 6) of zone 1. The outer end of each of

spouts

70, 80 is closed by a closure gate, designated 56B, 56C, respectively. Each of gates 56B, 56C is mounted on the outer end of a respective s'pout and is controlled by a sensor system similar to that previously described with reference to spouts 30. The system controlling spout 70 includes a hydraulic cylinder 508 connected to and operable for opening and closing spout gate 56B. The gate 56C of spout 80 is controlled by a similar cylinder designated 50C. The electrical sensors, relays and pumps controlling gates 56B and 56C have been omitted in FIG. 1 for purposes of clarity.

Since products removed by way of slag spouts 30, 70, 80 are normally in a molten or semi-molten state, induction heating coils 58A, 58B, 58C are provided surrounding each of slag spouts 30, 70, 80 toassure eff cient discharge of products therethrough. Obviously, spouts 30, 70, 80 must be fabricated of a suitable heat resistant material.

The removal of incineration products by way of slag spouts 30 can be enhanced by assuring a difference in the density of the products and the mass of material heated in zone 1. To additionally enhance removal of these products, convection currents can be created in the melted mass. For example, when high temperatures are employed, the heated material can resemble a boiling mass of molten lava.

It will be appreciated that it is not necessary in the practice of the invention for the closure gate of each spout, automatically to respond to the associated level sensor. It'is sufficiently advantageous to monitor the level and to have means provided for the reduction of the level at the option of the user. For example, the output of the electrode sensing system shown in FIG. 1 may be registered on a meter, the meter observed, and the gate opened manually by the observer.

Reference is now made to FIG. 3 wherein there is shown a' second incinerator, generally designated 3', constructed in accord with the present invention. As is evident, the construction of incinerator 3 is in many respects the same as that of incinerator 3, and the similar parts thereof are indicated by the same numbers used in the prior description of incinerator 3, with a differentiating prime added thereto. The major differences between incinerator 3' and incinerator 3 are the means for heating the mass within the lower zone, zone 1 of incinerator 3 and zone 1 of incinerator 3, and the absence of any auxiliary heating means for heating the upper zone, zone 2', of incinerator 3'.

In the operation of incinerator 3, a meltable mass of material, which may be electrically nonconductive but which typically is a metal or metal alloy, is charged to zone 1 and is there heated to its melting point by a combustion heater. As illustrated, the combustion heater includes a plurality of gas jets 90 supplied by gas source 92 and combustion supporting fluid source 94. Gas jets 90 are arranged in three vertically spaced banks, each bank including eight jets circumferentially spaced at regular intervals. In the cross-section of FIG. 3, some of jets 90 are illustrated off-set slightly from their actual position for the purpose of clarity of illustration of other portions of incinerator 3'. As will be evident, the number of banks of gas jets and number and arrangement of jets in each bank may be varied as desired and according to the size of the incinerator and nature and quantity of refuse material incinerated therein and the nature of the particular gas and combustion supporting fluid employed.

As illustrated, jets 90 are fixed in a superstructure wall 96 generally surrounding zone 1 and the bottom portion of zone 2'. A cavity 95 is formed between walls 4' and 96 which is sealed to the exterior of the incinerator, but which has

ports

97 and 98 communicating with zone 2'..

In the heater of incinerator 3', the combustion supporting fluid most generally supplied from source 94 will be air or oxygen-enriched air, delivered under pressure. The air is combined with gas from source 92, injected as a mixture into cavity 95 through jets 90, and there combusted. Combustion of the gases within cavity 95 provides heat for melting the mass in zone 1' and maintaining it at the desired temperature. Additionally, the combustion raises the pressure within cavity 95, forcing a flow of unburned or residual gas and combustion products through

ports

97 and 98 and into zone 2. Here, the residual gas is combined with incoming refuse and additional combustion fluid introduced (through tuyeres 26) into zones 2 for the purpose of burning that refuse when it undergoes further burning. In this manner, combustion products and unburned gases are recycled within the incinerator rather than being exhausted into the atmosphere, thus resulting in greater efficiency and lower pollution than other incinerators using combustion heating devices.

A fine degree of heat control is provided by the utilization of gas jets as will be appreciated by those familiar with ordinary gas burning devices such as cooking stoves or laboratory burners. Once the mass in zone 1' is melted much of the heat is supplied by the burning of the refuse itself. The amount of external heat provided by the jets may be decreased t precisely the point at which the process is self sustaining but immediately increased when conditions, i.e., the input of different kinds of refuse, require additional heat.

Typical temperatures which may be obtained from various gases are given in the chart below.

GAS lbs air/lb gas TEMP "F Butane 30.47 3640 Propane 23.82 3660 Oil Gas 2.IO 3670 Coal Gas 4.53 3645 Methane 9.4 I 3565 Carbonated 4.6I 3725 Water Gas Producer Gas 1.00

As will be understood by those skilled in the art, the jets may be ignited by any conventionalmeans, electric spark devices for example.

As shown, incinerator 3' includes removal spouts located in the lower portion of zone 1' in position for drawing off a desired part of the melted mass. The outer end of each spout 100 is covered by a trap door 102, which may be held closed by mechanical, magnetic, or other similar known devices. The door is raised by a simple chain 106 and pulley 104. If desired, of course, door 102 could be controlled by a sensing system such as that previously described with reference to incinerator 3.

FIGS. 4 and v5 illustrate a third incinerator, generally designated 3' constructed in accord with the present invention. As the construction of incinerator 3" is in many respects the same as that of incinerator 3, the similar parts thereof are indicated by the same numbers used in the prior description of incinerator 3, with a differentiating double prime added thereto. The major differences between incinerator 3" and incinerator 3 are. the addition to' incinerator 3" of means for melting any slag crust at the upper surface of the mass, and the absence in incinerator 3 of the other zone two auxiliary heating means and sensing system of incinerator 3.

As shown, incinerator 3 includes three electric arc electrodes extending through wind box 24" and arranged for movement into and out of zone 2" through respective ones of tuyeres 26". Each electrode 120 is movable axially thereof between a retracted position (shown in FIG. 5) in which the electrode is aligned. with but removed from the respective tuyere 26", and an arcing position (shown in FIG. 4) in which the inner end of the electrode is closely adjacent the top of the melted mass. Driving motors 122 are provided on the exterior of wind box 24" in engagement with respective ones of electrodes 120 for moving the electrodes between the two positions. A power supply 124 is connected to electrodes 120 for applying threephase current to them in the manner of the conventional Heroult arc furnace. v

During normal incineration, electrodes 120 are held in their retracted position (as in FIG. 5) and the noncombustible products of incineration are removed from incinerator 3" through spouts 30". As shown, the outer end of each spout 30" is covered by a trap door 56A", which is normally held open by a simple chain 126 and pulley 128. Amagnetic or other mechanical catch (not shown) is provided for holding door 56A" in its closed position.

When door 56A" is held open, the non-combustible products are continuously flow through spouts 30". If the slag on the top of the molten mass builds-up or bridges to such an extent that the products will not flow properly, electrodes 120 are advanced by driving motors 122 into their arcing position (FIG. 4) in which each electrode is spaced slightly above the slag surface. Electric power is then applied to the electrodes from source 124, and th'e'heat of the resulting arc melts the built-up slag, permitting it to flow freely from spouts 30". When the build-up of slag has been eliminated,

the electrodes are withdrawn.

Incinerator 3" also may be operated in a manner similar to that previously described with reference to incinerator 3, in which trap door 56A" is held in its normally closed position until the level of the molten mass (increased by addition of combustion products) has In these two modes, introduction of refuse into incinerator 3" is normally stopped during use of electrodes 120 and is resumed after the electrodes have been withdrawn into their retracted position. Alternatively, the electrodes may be maintained in or near their arcing position during introduction of refuse and powered as often as necessary to reduce slag build-up or promote incineration. This alternative more continuous use of electrodes 120 causes more complete combustion of the air introduced into zone 2" through tuyeres 26", thereby reducing the rate of slag build-up in the same manner as the auxiliary heating means previously described with reference to incinerator 3.

Many other modifications of the present invention will fall within the scope and spirit of the appended claims. For example, other methods, such as conventional combustion gas jets or plasma generating techniques, may be employed to supply additional heat to the portion of zone two directly above the heated mass. Also, energy recovery and conversion means may be employed, permitting utilization of the heat produced by the incineration to generate the electricity required to power the electrical heaters or induction coils used to heat the mass.

What is claimed is:

1. The method of incinerating refuse of the type including at least one of combustible and noncombustible materials, said method comprising the steps of:

providing adjacent first and second zones, said first zone being a heat generating zone and said second zone being an incineration zone;

maintaining within said first zone a mass of substantially non-combustible material, said first zone comprising a peripheral wall within which said mass is maintained and the upper level of said mass approximately defining the boundary between first and second zones;

providing a heater without the interior surface of said peripheral wall of said first zone and heating said mass by means of said heater to temperature sufficient to cause incineration of said one; and, introducing said one into said second zone whereby heat from said mass causes incineration of said one.

2. The method of claim 1 including the step of introducing combustion supporting fluid into said second zone, but not into said first zone.

3. The method of claim 1 including introducing a combustion-supporting fluid into said second zone at a plurality of relatively spaced points at the boundary of said second zone and heating said fluid prior to the introduction of said fluid into said second zone.

4. The method of claim 1 wherein said mass is metal.

5. The method of claim 4 wherein said mass is maintained at a temperature greater than the melting point of said metal.

6. The method of claim 1 including removing products of incineration of said refuse from said incinerator.

7. The method of claim 6 wherein said one is noncombustible materials, and including the step of removing products of combustion of said one from adjacent the boundary between said first and second zones.

8. The method of claim 7 including removing said products of combustion of said one through a discharge spout placed adjacent said boundary, and including the step of heating said spout prior to removal of said products therethrough.

9. The method of claim 6 including the step of sensing the level of said products of combustion of said one, and removing said products when said sensed levels reaches a predetermined level.

10. The method of claim 9 wherein said products of combustion of said one are removed through a spout positioned adjacent said boundary, and including the step of blocking said spout to prevent flow of said products therethrough when said sensed level is below said predetermined level.

11. The method of claim 1 including the step of removing substantially molten material from said incinerator ata point not above said boundary.

12. The method of claim 1 1 including the step of providing means for removing said substantially molten material from said incinerator at a plurality of vertically spaced points not above said boundary, selecting one of said points, and removing said substantially molten material through said selected point.

13. The method of claim 11 wherein said substantially molten material is a portion of said mass.

14. The method of claim 1 including the step of varying the energy input to said heater with reference to one of the composition and quantity of said refuse.

15. The method of claim 1 wherein said wall is of refractory material.

16. The method of claim 1 wherein said heater is an electrical induction coil, and including the step of applying electrical powerto said coil to heat said mass by one of direct, indirect and semi-direct induction heat- 17. The method of claim 1 wherein said wall is of refractory material and said mass is heated by applying heat exteriorly of said wall.

18. The method of claim 17 wherein said heater is a combustion heater arranged to heat the exterior of said wall.

19. The method of claim 18 including the step of introducing products of combustion of said heater into said second zone.

20. The method of claim 1 including the step of varying one of the temperature and size of said mass with reference to one of the composition and quantity of said refuse.

21. The method of claim 20 including the step of varying said temperature with reference to said composition.

22. The method of claim 1 wherein products of combustion of said one tend to collect as slag adjacent said boundary, and including the step of applying additional heat to said slag.

23. The method of claim 22 including the step of placing an additional heater adjacent said second zone in position for heating said slag and applying said additional heat by means of said additional heater.

24. The method of claim 23 wherein said additional heater is an induction coil.

I 27. The method of claim 1 wherein said heater is an electrical'heater without the interior surface of said wall, and including the steps, of utilizing the heat produced by said incineration to generate electrical power,

- applying said electrical power to said heater, and heat- I ing said mass by means of said generated power.

Claims

1. The method of incinerating refuse of the type including at least one of combustible and non-combustible materials, said method comprising the steps of: providing adjacent first and second zones, said first zone being a heat generating zone and said second zone being an incineration zone; maintaining within said first zone a mass of substantially noncombustible material, said first zone comprising a peripheral wall within which said mass is maintained and the upper level of said mass approximately defining the boundary between first and second zones; providing a heater without the interior surface of said peripheral wall of said first zone and heating said mass by means of said heater to temperature sufficient to cause incineration of said one; and, introducing said one into said second zone whereby heat from said mass causes incineration of said one.

4. The method of claim 1 wherein said mass is metal.

7. The method of claim 6 wherein said one is non-combustible materials, and including the step of removing products of combustion of said one from adjacent the boundary between said first and second zones.

11. The method of claim 1 incluDing the step of removing substantially molten material from said incinerator at a point not above said boundary.

12. The method of claim 11 including the step of providing means for removing said substantially molten material from said incinerator at a plurality of vertically spaced points not above said boundary, selecting one of said points, and removing said substantially molten material through said selected point.

15. The method of claim 1 wherein said wall is of refractory material.

16. The method of claim 1 wherein said heater is an electrical induction coil, and including the step of applying electrical power to said coil to heat said mass by one of direct, indirect and semi-direct induction heating.

17. The method of claim 1 wherein said wall is of refractory material and said mass is heated by applying heat exteriorly of said wall.

24. The method of claim 23 wherein said additional heater is an induction coil.

25. The method of claim 23 wherein said additional heater comprises a plurality of retractable electrodes movable between a first position closely adjacent said slag and a second position spaced from said slag, and a source of power for applying electrical power to said electrodes.

26. The method of claim 23 wherein said additional heater is plasma generating means.

27. The method of claim 1 wherein said heater is an electrical heater without the interior surface of said wall, and including the steps of utilizing the heat produced by said incineration to generate electrical power, applying said electrical power to said heater, and heating said mass by means of said generated power.