CA2184653C - Plant for gasification of waste - Google Patents

Abstract

A plant for gasification of waste such as municipal solid waste, boxed-type biomedical waste, granular contaminated solid, and liquid toxic waste, and the like, comprising a refractory lined reactor vessel; a feed mechanism adapted to feed a predetermined type of waste into said reactor vessel with minimum exposure to atmospheric air; and a processing platform in said reactor vessel for initially receiving said waste.

Description

l PLANT FOR GASIFICATION OF WASTE
BACKGROUND OF THE INVENTION

I . Field of the Invention The present invention relates to a waste disposal plant and, in particular, to a plasma arc torch waste disposal plant for handling various kinds of waste.

2. Prior Art of the Invention The daily generation of solid wastes is a fact of life in industrialized society and their disposal is becoming an ever-increasing problem. In the search for non-polluting, more efficient and less costly disposal, Energy from Waste (EFW) technologies are being developed such as gasification by means of a plasma arc torch in an enclosed, refractory lined, reactor vessel.

Plasma gasification is a non-incineration thermal process which uses extremely high temperatures in an oxygen starved environment to completely decompose input waste material into very simple molecules. The extreme heat and lack of oxygen results in pyrolysis of the input waste material, as opposed to incineration; pyrolysis being the thermal decomposition of matter in the absence of oxygen. The by-products of the process are a combustible gas and an inert slag.

The heat source in a plasma gasification system is a plasma arc torch, a device which produces a very high temperature plasma gas. The plasma arc centreline temperature can be as high as 50,O00OC, and the resulting plasma gas has a temperature profile of between 3,000 and 8,000'C.

A plasma gasification system is designed specifically for the type, size and quantity of waste material which must be processed. A refractory lined reactor vessel is preheated to a minimum wall temperature of approximately 1100 C before any processing commences, the actual ambient temperature is determined by the waste material being processed. The very high temperature profile of the plasma gas then provides an optimum processing zone within the reactor vessel through which all input waste material is forced to pass. The reactor vessel operates effectively at atmospheric pressure. In this environment, all of the volatile input material is completely decomposed, while non-volatile input material, such as glass, metals and dirt, melt and chemically combine to form a glassy slag.

Pyrolysis through plasma gasification provides for virtual complete gasification of all volatiles in the source material, while non-combustible material is reduced to an inert slag. With municipal solid waste as the input waste material, the product gas and slag

3 have very distinct characteristics. The product gas is high in hydrogen and carbon monoxide, with traces of methane, acetylene and ethylene; therefore, it can be combusted very efficiently resulting in carbon dioxide and water vapour being the majority of gaseous exhaust to the atmosphere. The slag is a homogeneous, silicometallic mass, monolithic in texture with leachate toxicity levels orders of magnitude lower than those of current landfill regulations.

Plasma gasification systems offer considerable versatility as to throughput capacity.
Plasma arc torches are available commercially in sizes ranging from 50 kW to over 60 MW; therefore, plasma gasification systems can be implemented at virtually any size capacity. The reactor vessel and plasma arc torch are specifically sized to the type and quantity of waste material to be processed. There are many plasma arc torch manufacturers who could provide equipment for use in such systems.
Individual torches can be selected to operate in particular waste processing applications where their operational capabilities can be best applied.

Applicant's United States Patent No. 5,280,757 issued January 25, 1994 describes plasma gasification of waste. A gasification plant is required which is useful for processing of many kinds of waste, such as municipal solid waste, boxed waste, liquid waste and granular waste. This processing must be efficient and safe, to avoid environmental contamination.

4 Several United States patents relating to waste disposal vessels are:
United States Patent No. 4,989,522, issued February 5, 1991;
United States Patent No. 5,095,828, issued March 17, 1992.

SUMMARY OF THE INVENTION

The present invention provides a plasma gasification plant which can process many forms of solid and liquid waste such as, for example, municipal solid waste, boxed-type waste (i.e. biomedical waste), liquid waste and granular-type waste.
Waste feed and processing mechanisms are provided to efficiently and safely process such wastes.
According to a broad aspect of the present invention, there is provided a plant for gasification of waste such as municipal solid waste, boxed-type biomedical waste, granular contaminated solid, and liquid toxic waste, and the like, comprising:
a refractory lined reactor vessel; a feed mechanism adapted to feed a predetermined type of waste into the reactor vessel with minimum exposure to atmospheric air; and a processing platform in the reactor vessel for initially receiving the waste.

DESCRIPTION OF THE INVENTION

It has been found that the manner in which the waste material is fed into the reactor vessel can affect the efficiency of processing. The feed systems also affect the possibility of environmental contamination by release of hazardous gas to the environment.

The present plant includes a plurality of feed mechanisms to accommodate solid type

5 waste material such as municipal solid waste, boxed-type waste material such as hospital biomedical waste, granular-type waste material such as contaminated soil and liquid waste such as PCB oils. The feed mechanisms are capable of preventing problematic amounts of air from entering the reactor vessel along with waste material.
The feed systems are also capable of preventing the passage therethrough of gases from the vessel to the environment.

The plant includes a solid waste feed mechanism. The mechanism is useful for feeding any type of solid waste into the reactor vessel for processing. The mechanism provides an access chute to the interior of the vessel having at least a pair of gas-tight barriers. The first gas-tight barrier is provided adjacent to the outboard end of the chute, while the second barrier is positioned in the chute, intermediate to the first barrier and the reactor vessel. The barriers act to provide a gas lock whereby atmospheric air and hazardous gases can be trapped and evacuated, if required, thereby avoiding the passage of such gases along the chute between the plant exterior and the reactor vessel during the feed process. The evacuation of the air or gases in the gas lock is carried out by a purging system which acts between the barriers.

6 The solid waste feed mechanism is provided with a ram mechanism for forcing the waste along the chute and into the vessel. The portion of the chute adjacent the vessel is formed to cooperate with the shape and position of the ram to allow the formation of a loose plug in the chute by compactable solid waste material. The plug, when formed, acts in the same way as the second barrier against passage of heat and large quantities of gas. Thus, the formation of a plug formed of compactable waste allows further wastes to be fed behind the plug without activation of the second barrier.

A box feeder is provided on the plant of the present invention. Hospital biomedical waste is normally packaged in boxes. Since this waste material can be infectious, it is essential to input this waste to the reactor in as-received form. Boxed type biomedical waste often includes containers of liquid. If the liquid is not released from the containers prior to gasification, the containers will burst inside the vessel causing a rapid expansion of gaseous product.

The box feeder comprises a chute having an air lock chamber substantially as described with reference to the solid waste feed mechanism. The chute is sized to accept boxes. Where required, the box feeder further comprises a means for forcing the box along the chute and into the reactor vessel, for example a hydraulic ram, and a means for piercing the box and its enclosed materials, to break open any containers of liquid within the box.

7 The box feeder can be a separate chute opening into the vessel or can be incorporated into the solid waste feed chute.

To facilitate the processing of granular-type waste such as, for example, contaminated soil, a screw feed is provided. The screw feed is comprised of a spiral blade in a housing and is provided in association with an air lock chamber. The screw feed is positioned to input the materials into the vessel at the processing zone. In one embodiment, the screw feed is positioned outside the vessel to feed the material through a port positioned such that it drops into the processing zone. In another embodiment the screw feed is mounted to be retractably, extendable into the vessel for input of waste.

A port in the vessel permits the insertion of a liquid waste feeder. The liquid waste feeder is a spray head which injects wastes, for example by spraying or atomization.
The spray head can be positioned to direct the wastes into the hottest portion of the plasma gas stream.

The liquid feed port can also function to inject steam into the vessel. The injection of steam enhances the processing of dry carbonaceous type waste.

Most waste materials will process very readily once introduced to the high temperature processing zone within the reactor vessel. Normally, processing is efficient even if

8 the input waste material falls into the molten slag pool prior to it being fully gasified.
However, some waste materials, particularly those which contain a high concentration of elemental carbon, should be retained in a high temperature oxidizing environment until they are completely gasified. In the plant of the present invention, a processing platform is formed within the reactor vessel to receive the input waste material. The processing platform is formed such that as the material decomposes, the gaseous constituent exits the vessel and the molten solid constituent flows into the molten slag pool. Flow of the molten solid constituent away from the processing platform and into the slag pool, ensures the remaining unprocessed material is continuously exposed to the desired high temperature oxidizing environment.

A continuously operating plasma gasification plant requires the removal of slag from the vessel during processing without any adverse impact on the overall efficiency of the process. A means for allowing the molten slag to flow from the vessel during processing, without opening of the vessel to the ambient environment, is provided.

The input of waste material into the reactor vessel in discrete quantities causes fluctuations in the rate of generation of gaseous product which in turn can cause fluctuations in the pressure within the vessel. Maintenance of atmospheric pressure is desired to maintain the efficiency of the system. For example, these fluctuations can be quite dramatic in the processing of boxed material such as biomedical waste, which can contain large concentrations of plastics and cellulosic material.
The product

9 gas handling system of the present plant is responsive to such fluctuations in product gas flow to maintain atmospheric pressure within the reaction zone. A variable speed induction system has been provided which is responsive to fluctuations in the rate of generation of product gas.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present invention will now be described in detail in conjunction with the annexed drawing figures, in which:

Figure 1A is a side elevational view of a plant according to the present invention with a side wall of the reaction vessel cut away to expose the vessel interior;

Figure IB is a plan view of a reaction vessel useful in the present invention;

Figure 2 is a side sectional view of a solid waste feed mechanism useful in the present invention;

Figures 3A and 3B are side sectional and plan views, respectively, of a boxed waste feed mechanism useful in the present invention;

Figure 4 is a side section view of a granular waste feed mechanism useful in the present invention; and Figure 5 is a side section view of a liquid waste feed mechanism useful in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to Figures 1A and 1B of the drawings, a side elevational view of a gasification plant 10 (Figure 1A only) according to the present invention is

10 shown. Plant 10 (Figure 1A only) has a reaction vessel 11 which has been cut away to reveal the interior thereof. Reaction vessel 11 houses a plasma torch (Figure 1A only) for gasification of waste introduced thereto by means of waste feed mechanisms. Mechanism 12a (Figure 1A only) supports the plasma torch 12 (Figure 1A only) and permits rotational movements to change the focal point of the plasma gases for optimization of the processing effect.

The waste feed mechanisms include: a solid-type waste feed mechanism, indicated generally at 13; a box-type waste feed mechanism, indicated generally at 14 (Figure IA only); a granular-type waste feed mechanism, indicated at 15 and a liquid-type waste feed mechanism, indicated generally at 16 (Figure 1A
only).
Mechanisms 13, 14 (Figure 1A only) and 15 feed the waste onto a processing platform 17, within vessel 11, such that it is directly in the processing zone of the plasma torch. Processing

11 platform 17 is formed to have an incline sufficient to cause the molten slag, resulting from processing, to flow away from platform 17, as indicated by arrows, and toward a reservoir 18 where a molten slag pool forms. A weir 19 (Figure IA
only) is provided at a slag exit port 20 which provides for removal of molten slag during processing without opening of vessel 11 to the ambient environment. A
gas exit port 20a (Figure IA only) is provided as an exhaust for gases. The plant is substantially completely gas-tight when in use with the only access to the reaction vessel being by the feed mechanisms and the exit ports, which are sealable.
Plant 10 (Figure 1 A only) is mounted on a platform 21 (Figure 1 A only), which is hydraulically tiltable about pivotal connection 22 (Figure IA only) for emptying all or a portion of the molten slag, as required, after completion of a gasification process.

Referring to Figure 2, solid-type waste feed mechanism 13 is shown in greater detail.
Mechanism 13 comprises a feed-hopper 25 which opens into a chute 26, which in turn opens into reaction vessel 11. Feed-hopper 25 diverges slightly as it opens into chute 26 to prevent blockage. A gas-tight door 27 is provided at the outboard end of hopper 25 and a hydraulically-driven, heat resistant, and preferably gas-tight, gate 28 is provided in chute 26. When door 27 is closed and gate 28 is in its lowered position, a heat and gas lock chamber is formed therebetween. Chamber 29 can be purged through valves 30a, 30b to prevent passage of air or gases between the atmosphere and the reaction vessel. Purged gas from the reaction process is returned to the reaction

12 vessel through lines (not shown), while air is vented to the atmosphere or into a combustion chamber as part of its excess air supply.

A ram 31 is provided to move waste along chute 26. Ram 31 is driven by hydraulic mechanism 32. The shield 33 of ram 31 is formed to prevent waste from falling into hydraulic mechanism 32 and is sized to fit within chute 26. Hydraulic mechanism 32 is enclosed by a gas-tight housing and is actuated by a power source having controls such as limit switches. The limit switches control the length of the ram's stroke, to thereby control the amount of waste fed to the vessel with each stroke.

In use, waste is input to feed-hopper 25 while ram 31 is in the retracted position and gate 28 is in its lowered heat and gas-tight position. Door 27 is then closed and atmospheric air is purged from the mechanism with nitrogen gas through valves 30a and 30b. Gate 28 is then raised to permit the waste to be moved along chute 26 by action of ram 31 and into vessel 11, as indicted by arrow W. Relief valves (not shown) can also be provided to prevent a build up of pressure in the hopper beyond safe levels.

When the waste is fully input to vessel 11, gate 28 is again lowered and the gases are purged, thereby allowing door 27 to be opened without releasing hazardous gases to the environment.

13 In an embodiment, ram housing can be formed such that it cooperates with the cross-sectional shape of chute 26 to allow the formation of a plug of compacted waste when ram 31 is activated. Once a plug is formed, the plug will act as a heat and gas-tight barrier, in the same way as gate 28 and allow purging of gas behind the plug and opening of door 27. Such a system allows for continuous feeding of waste to the hopper as long as a complete plug remains in chute 26. To ensure a good heat and gas-tight condition, gate 28 can be lowered on top of the plug.

Referring to Figures 3A and 3B, an embodiment of box-type waste feed mechanism 14 is shown. Mechanism 14 comprises a box feed chamber 35 which opens into a feed chute 26. Chute 26 in turn opens into vessel 11 (Figure 3B
only). In the embodiment, as shown, box feed mechanism 14 is associated with the solid waste feed mechanism and chamber 35 is mounted at a side of chute 26.
Chamber 35 has a gas-tight door 36 through which boxes can be fed to chamber 35. A gas-tight gate 37 (Figure 3B only) separates chamber 35 from chute 26.
Gate 37 (Figure 3B only) is actuated by an air or hydraulic mechanism 38 (Figure 3B only) between an open position (as shown in Figure 3B) and a closed, gas-tight position. When door 36 is closed and gate 37 (Figure 3B only) is in its gas-tight position, a gas lock is formed in chamber 35.

A plunger 40 is provided to move the boxed waste from chamber 35 into chute 26. Ram 31 moves box waste along chute 26 and into vessel 11 (Figure 3B only).

14 In the preferred embodiment, as shown, a box piercing apparatus 41 (Figure 3A
only) is mounted in chute 26 to be actuated to pierce a box and its contents to break open any containers therein. Apparatus 41 (Figure 3A only) comprises a plurality of stainless steel piercing rods 42 having sharpened tips 42' (Figure 3A
only) mounted on a moveable base 43. Base 43 is connected to the shaft 44 (Figure 3A only) of a hydraulic mechanism. Apparatus 41 (Figure 3A only) is enclosed in a gas-tight housing 46 (Figure 3A only).

In use, gate 37 (Figure 3B only) is closed and boxed waste is input to chamber through door 36. Door 36 is then closed and sealed. To avoid the requirement for a purging system, preferably chamber 35 is sized to correspond to the shape and size of the boxed waste to be introduced so that substantially all of the atmospheric air is forced from the chamber by input of a box. Alternately, a purging system can be installed in chamber 35 and used after sealing of door 36 to remove atmospheric air. Gate 37 (Figure 3B only) is then opened and plunger 40 is actuated to move the box into chute 26. Plunger 40 is retracted and gate 37 (Figure 3B only) is closed. Hydraulic ram 31 is actuated to move the box into alignment with piercing apparatus 41 (Figure 3A only). Base 43 of apparatus 41 (Figure 3A only) is lowered such that rods 42 pierce the box and its contents.
Apparatus 41 (Figure 3A only) is thereafter raised and gate 28 is opened to allow ram 31 to move the box along chute 26 and into vessel 11 (Figure 3B only).
Referring now to Figure 4, an embodiment of a granular waste feed mechanism

15 is shown. Mechanism 15 comprises a feed hopper 50 which opens into a tube 51 housing a rotatable spiral blade 52. Spiral blade 52 has sufficiently small diameter, when compared with that of tube 51 to prevent jamming of waste. The clearance between the blade and the tube can be determined by the granule size of the input waste.

A housing 53 is sealably mounted about an end 51' of tube 51 . Housing 53 opens into vessel 11 and has mounted therein a gas-tight, heat resistant gate 54.
Gate 54 is 5 hydraulically driven between an open position and a gas-tight, sealed position. A gas-tight door 55, disposed on the outboard end of feed-hopper 50, acts with gate 54 to form a gas-lock chamber 56 therebetween which can be purged by use of valves 57a, 57b and 57c.

Mechanism 15 is adapted to feed the waste directly to the processing zone of the 10 reaction vessel by insertion of tube 51 into reaction vessel 11. Tube 51 is slidably moveably within housing 53 between a position wherein tube 51 is retracted from vessel 11 and gate 54 can be closed and a position, as shown in Figure 4, wherein a portion of tube 51 extends within vessel 11. Tube 51 is driven by a hydraulic mechanism 58.

15 In use, with mechanism 15 fully retracted from vessel 11, gate 54 and door 55 are sealed and shaft 51 and chamber 56 are purged with nitrogen by use of valves 57a and 57c. Door 55 is opened and granular waste is fed to feed-hopper 50. The waste drops down by gravity into tube 51 and about blade 52. Door 55 is then closed and chamber 56 is purged with nitrogen by valves 57b and 57c. Gate 54 is opened and

16 hydraulic mechanism 58 is actuated to drive tube 51 within housing 53 and past gate 54 to extend into vessel 11. Spiral blade 52 is then actuated to rotate within tube 51 to carry the waste along tube 51 and input it to vessel 11.

When desired, rotation of blade 52 is stopped and tube is retracted from vessel 11 and past gate 54 by hydraulics 58. Gate 54 is then closed and the process can be repeated.
Referring to Figure 5, a feed mechanism 16 for liquid waste is shown.
Mechanism 16 comprises a spray nozzle 60 for injecting (i.e., spraying or atomizing) liquids.
Liquids are fed by a pump 61 to nozzle 60 from reservoir 62 through line 63.
Nozzle 60 is preferably positioned in vessel 11 such that the liquid is fed directly into the processing zone of the plasma torch 12.

When liquid waste is not being handled, steam can be fed through nozzle 60 to assist in the processing of dry carbonaceous waste.

The mechanisms for feeding solid waste, boxed waste, granular waste and liquid waste, as described, need not all by present in the same plant, as the presence of more than one may not be required for the particular processing of waste being undertaken.

Alternately, the mechanisms can all be present in the plant at all times, but only be used as needed.

Claims (24)

THE EMBODIMENTS OF THE INVENTION FOR WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A waste disposal system for gasification and melting of waste materials, said waste disposal system nominally in contact with the ambient atmosphere and comprising:
a single oxygen-starved closed reactor vessel contained within said waste disposal system, said reactor vessel substantially closed to the ambient atmosphere, said reactor vessel comprising a bottom portion serving as a slag area;
an active feed mechanism operatively connected to said reactor vessel and adapted to actively feed waste into said reactor vessel, said feed mechanism comprising barrier means for substantially eliminating the inflow of air from the ambient atmosphere into said reactor vessel and for blocking the expulsion of reactor vessel byproduct gases into the ambient atmosphere;
a plasma arc torch operatively connected to said reactor vessel, said plasma arc torch located for plasma arc activity within said reactor vessel to produce a high temperature processing zone to gasify or melt any waste which is actively fed into said zone; and at least one waste-receiving reservoir located within said reactor vessel, each said waste-receiving reservoir being positioned to initially receive and retain any waste which is actively fed to said reservoir for thermal decomposition and melting of such waste by said plasma arc torch, said waste-receiving reservoir comprising a substantially flat receiving platform and a dam at least partially surrounding said substantially flat platform.

2. The waste disposal system of claim 1 wherein there is an opening in said dam and an inclined path through said opening in said dam to permit melted waste components or byproducts to move to a slag pool area.

3. The waste disposal system of claim 2 wherein said inclined path through said opening in said dam has a slope of two degrees or less.

4. The waste disposal system of claim 1 wherein said reactor vessel is lined with refractory material.

5. The waste disposal system of claim 1 wherein said active feed mechanism comprises an elongated gas-tight chute having a first end outboard to and remote from said reactor vessel and a second end opening into said reactor vessel, and wherein said active feed mechanism further comprises means for both substantially eliminating inflow of air from the ambient atmosphere into said reactor vessel and for blocking the expulsion of reactor vessel byproducts into the ambient atmosphere.

6. The waste disposal system of claim 5 wherein said barrier means for both substantially eliminating the ingestion of air from the ambient atmosphere into said reactor vessel and for blocking the expulsion of reactor vessel byproducts into the ambient atmosphere comprises a first gas-tight barrier and a second gas-tight barrier within said chute, said first gas-tight barrier being located adjacent to said first end outboard to and remote from said reactor vessel, and said second gas-tight barrier being located within said chute intermediate to said first gas-tight barrier and a second end chute opening into said reactor vessel to thereby provide a gas lock whereby ambient atmospheric air and hazardous gases are trapped between said first gas-tight barrier and said second gas-tight barrier.

7. The waste disposal system of claim 6 wherein means is provided for evacuating any ambient atmospheric air and hazardous gases trapped between said first and second gas-tight barriers.

8. The waste disposal system of claim 6 wherein means is provided for purging ambient atmospheric air and any hazardous gases produced within the reactor vessel and then trapped between said first and second gas-tight barriers.

9. The waste disposal system of claim 5 wherein said active feed mechanism comprises one or more feed components adapted to actively feed solid waste or waste in solid containers into said reactor vessel, said one or more feed components comprising a ram mechanism for forcing solid waste along the chute and into the reactor vessel.

10. The waste disposal system of claim 5 wherein said active feed mechanism comprises one or more feed components adapted to actively feed granular waste into said reactor vessel, said one or more components comprising a screw feed for forcing granular waste along the chute and into the reactor vessel.

11. The waste disposal system of claim 10 wherein said screw feed forces granular waste onto said platform.

12. The waste disposal of claim 10 wherein said screw feed comprises a spiral blade in a housing, said screw feed being operably connected with a feed hopper, said spiral blade being sized to provide sufficient clearance and to prevent jamming of the largest particle size within said housing.

13. The waste disposal system of claim 12 wherein said screw feed housing and said feed hopper have a first end outboard of and remote from said reactor vessel and a second end opening into said reactor vessel, and wherein said screw feed housing and said feed hopper further comprise a gas-tight door and a gas-tight and heat resistant gate to form a gas lock chamber, said gas-tight door being disposed on said outboard end of said feed hopper, and said gas-tight heat resistant gate being located adjacent to said second end opening into said reactor vessel.

14. The waste disposal system of claim 12 wherein means is provided for purging said screw feed housing and said feed hopper with nitrogen.

15. The waste disposal system of claim 5 wherein said active feed mechanism comprises one or more feed components adapted to actively feed liquid waste into said reactor vessel, said one or more components comprising a port located within the reactor vessel which permits the insertion of a liquid waste feeder comprising a spray head for injecting liquid waste by spraying or atomization into the reactor vessel.

16. The waste disposal system of claim 5 wherein said elongated gas-tight chute comprises means for piercing solid containers to break any containers of liquid within the solid containers prior to the containers of liquid being inserted into said reactor vessel.

17. The waste disposal system of claim 1 wherein said active feed mechanism comprises one or more feed components adapted to actively feed solid waste into said reactor vessel.

18. The waste disposal system of claim 1 wherein said active feed mechanism comprises one or more feed components adapted to actively feed waste in a solid container into said reactor vessel.

19. The waste disposal system of claim 1 wherein said active feed mechanism comprises one or more feed components adapted to actively feed granular waste into said reactor vessel.

20. The waste disposal system of claim 1 wherein said active feed mechanism comprises one or more feed components adapted to actively feed liquid waste into said reactor vessel.

21. A waste disposal system for gasification and melting of waste, said waste disposal system comprising:
a reactor vessel comprising one or more processing platforms to initially receive the waste for thermal decomposition and melting, and a bottom portion within said reactor vessel adjacent to said one or more platforms serving as a slag area;
a feed mechanism operatively connected to said reactor vessel and adapted to feed waste to said one or more processing platforms; and a plasma arc torch operatively connected to said reactor vessel to produce therein a high temperature processing zone to gasify or melt the waste fed therein.

22. The waste disposal system of claim 21 wherein said one or more processing platforms comprising a substantially flat section and a dam at least partially surrounding said substantially flat section to receive and retain the waste.

23. The waste disposal system of claim 22 wherein said one or more processing platforms enabling slag to flow therefrom through an opening in said dam toward said slag area.

24. The waste disposal system of claim 23 wherein said slag flows through said opening along an inclined path leading to said slag area.