WO2015050493A1

WO2015050493A1 - Bio waste incinerator apparatus and method

Info

Publication number: WO2015050493A1
Application number: PCT/SE2014/051128
Authority: WO
Inventors: Peter CLEVESTIG
Original assignee: Bioincendia Ab
Priority date: 2013-10-01
Filing date: 2014-09-26
Publication date: 2015-04-09

Abstract

An incinerator apparatus,effective for destroying organic and other combustible material, the apparatus comprising a container (1) and a heating vessel (6), the heating vessel arranged to receive the container inserted therein, the container and the heating vessel dimensioned such that an interspace (10) is formed between the heating vessel and the container in the inserted position. A coiled conductor (12) is arranged about the heating vessel and effective for heating by induction the heating vessel and container to a temperature that causes carbonization of combustible material in the container. An off-gas entrance passage(15) is arranged from the interior of the container to the interspace, and an off-gas exit passage (16) is arranged from the interspace towards the atmosphere, the interspace forming a first off-gas heat treatment chamber (10) defined between the heating vessel (6) and the container (1).

Description

TITLE

Bio waste incinerator apparatus and method

TECHNICAL FIELD The present invention relates to an incinerator apparatus arranged and effective for destroying organic and other combustible material by therm ochemical

decomposition or carbonization. More precisely, the invention refers to the field of incinerators which can be heated by induction from an electric conductor to a temperature which results in carbonization of combustible material placed in the incinerator apparatus. In analogy herewith, the present invention also refers to a method for destroying combustible material by induction generated incineration.

BACKGROUND AND PRIOR ART

Apparatus of this general concept are previously known in the art. Among them is the heating apparatus disclosed in WO 2006/ 1 1 1701 Al , particularly for heating materials contained within drums or other containers. This apparatus comprises a metal base plate with an induction heating coil beneath the plate. The container to be heated is placed on the base. A cylindrical jacket with a further induction coil in the jacket wall may be arranged about the container. On energizing the coils, induction currents flow in the metal base plate, and in the jacket wall if present, to produce heat that is transmitted to the container and its contents.

Another induction heated incinerator is disclosed in WO 2005/077844 Al . An induction heating coil is placed over a waste container, such as a drum can, which can be heated by induction. An AC current is applied to the coil to heat the drum can and the waste contained therein, melting the waste and the drum can as well.

None of the aforesaid solutions provide detailed advice on the treatment of vapor or off-gas which is generated during a process of extreme pyrolysis or carbonization. However, neutralization of off-gas may be of particular concern in many areas of activity such as in biological laboratories, clinics and other life science facilities etc. , which produce biological or biomedical waste that may result in toxic and environmentally hazardous or otherwise harmful substances in the off-gas during a process of thermochemical decomposition. A heat generating device aimed to avoid the discharge of environmental pollutants from a waste incineration device is disclosed in JP 2005141914 (A). A heat treatment chamber for a substance to be treated is arranged to be heated by an induction heating coil. The heat treatment chamber provides a straight passageway for the substance which is introduced in a lower end to rise through the treatment chamber which is heated to a temperature of up to approximately 2,500° C.

SUMMARY OF INVENTION

The present invention has for its general purpose to provide a bio-waste incinerator apparatus suitable for operation on site at facilities producing small to medium sized volumes of biological waste.

One object of the present invention is therefore to provide an incinerator apparatus arranged to manage destruction of infectious or other hazardous biological waste streams in-house, thus reducing the risks associated with off-site handling, transportation and destruction, as well as significantly reducing costs associated with the destruction of potentially hazardous biological waste.

The present invention also aims at providing an incinerator apparatus configured for destroying hazardous molecules in the off-gas by breakdown into their constituents before releasing a neutralized and harmless gas to the atmosphere. The objective is met by an incinerator apparatus comprising a high-temperature resistant metal container having a wall extending from a bottom of the container, the container defining a cavity for material to be destroyed, and a high-temperature resistant metal heating vessel having a wall that extends from a bottom of the heating vessel, the heating vessel arranged to receive the container inserted therein. The container and the heating vessel are dimensioned such that an interspace is formed between the heating vessel and the container in the inserted position. The incinerator further comprises a coiled conductor arranged about the heating vessel, the coiled conductor dimensioned for heating by induction the heating vessel and container to a temperature that causes carbonization of combustible material in the container. An off-gas entrance is arranged to permit passage of off-gas from the interior of the container to the interspace, and an off-gas exit is arranged to permit passage of off-gas from the interspace towards atmosphere, the interspace forming a heated first off-gas treatment chamber defined between the heating vessel and the container. In analogy herewith, the present invention provides a method for destroying organic and other combustible material. The method comprises:

• providing a container having a high-temperature resistant metal wall

extending from a bottom of the container, the container defining a cavity for material to be destroyed,

• providing a heating vessel having a high-temperature resistant metal wall extending from a bottom of the heating vessel, and arranging the heating vessel to receive the container inserted therein by dimensioning the container and the heating vessel such that an interspace is formed between the heating vessel and the container in inserted position,

• providing a coiled conductor about the heating vessel, and energizing the coiled conductor for heating the heating vessel and container by induction to a temperature that causes carbonization of combustible material in the container,

· wherein the off-gas produced from incineration is guided along the exterior of the container for heat treatment before being released to atmosphere.

In a preferred embodiment the off-gas is forced in a descending flow along the exterior of the container. This embodiment is realized in the incinerator apparatus by arranging the off-gas entrance in an upper region of the first off-gas treatment chamber, and arranging the off-gas exit in a lower region of the first off-gas treatment chamber, the off-gas being forced by its own inherent pressure in a descending flow through the first off-gas treatment chamber.

A valve is preferably arranged downstream from the off-gas exit to permit in open position the discharge of off-gas to the atmosphere. The valve may be an

electromagnetically controllable valve.

Thus in a preferred embodiment, the off-gas that is generated in the incineration process is forced in a descending flow along the exterior of the container, through a heated first off-gas treatment chamber which is provided by the interspace formed between the heated container and heating vessel walls, and which can be isolated from the atmosphere by control of a closure valve. The off-gas is in this manner provided a dwell time in a heated environment wherein the temperature can easily be raised to at least 850° C by proper dimensioning of the coiled conductor and the supplied amount of energy.

The off-gas exit from the first off-gas treatment chamber may be arranged in flow communication with the atmosphere via a pipe length that forms an off-gas pipe, the off-gas pipe surrounded by a coiled conductor which is effective for heating the off-gas pipe by induction.

In one embodiment guide vanes are arranged inside the off- gas pipe, the vanes guiding the off-gas from a central region towards the wall of the off-gas pipe. The guide vanes aid in heat treating the off-gas by allowing the gas to pass close to the heated wall of the off-gas pipe.

In one embodiment the off-gas pipe extends from an off-gas exit which is formed as a centrally located opening through the bottom of the heating vessel. The embodiment ensures equal flow path length and dwell time for off-gas in the first off-gas treatment chamber regardless of vertical route through the interspace between container and heating vessel.

The off-gas pipe is typically sized with considerably less diameter dimension than the diameter of the heating vessel. Hence, due to a moderate diameter dimension, the off-gas pipe may be instantly heated to effective temperature by energizing the coiled conductor for only a few seconds. This design ensures that upon startup of the incineration process no off-gas can escape to atmosphere without being subjected to effective heat treatment on its way through the off-gas pipe.

It is preferred, for reasons of effective heating and comfortable handling, that the heating vessel is fitted into a shroud of heat insulation material. The shroud of heat insulation material is preferably extended along the exterior of the off-gas pipe as well.

The incinerator apparatus can be made operable in most laboratory or commercial facility environments through a power control circuit which is operating on a widely available 3-phase, 400 V power grid. The power control circuit is effective for supplying a high frequency alternating current to the coiled conductor. The power control circuit comprises a frequency converter supplying alternating current at a frequency in the order of 5-50 kHz.

The coiled conductor may be a copper tube connectable to a cooling water or equivalent circulation system, effective to maintain the conductor surface temperature below hazardous levels.

An incinerator apparatus may further advantageously comprise monitoring means for monitoring at least one of the following operation parameters: temperature, gas pressure, gas flow, gas constituents. Control means may further be arranged for controlling at least one of the following operation parameters: temperature, gas pressure, gas flow. An air injection system for regulation of gas pressure in the incinerator apparatus may further be arranged.

In one embodiment, the heat treatment of off-gas is separated into two stages, providing a second off-gas treatment chamber, preferably in the form of a burn chamber, arranged in flow communication with the interspace so that off-gas that has undergone a first heat treatment in the interspace can be received and subjected to a second heat treatment before being released from the incinerator apparatus. In this embodiment, the biological waste placed in the container is heated to a temperature in the interval 500-750° C with a limited amount of oxygen to provide a partial oxidation or partial incineration. In this embodiment, the first heat treatment is a pre-heating stage whereas the second heat treatment provides a combustion of the off-gas. The off-gas released from the chamber is subjected to a heat treatment in the interspace, as described above but at a lower temperature, and is thereafter conveyed to a second off-gas treatment chamber for a second heat treatment with ample oxygen for complete incineration/ combustion.

The off-gas is mixed with a pre-heated air flow to provide sufficient oxygen for a complete combustion and the mixture of off-gas and air is ignited and heated to a temperature above 850° C for at least two seconds. The supply of off-gas to the second treatment chamber is controlled to allow for a complete combustion, and after the second heat treatment the remaining off-gas can be subjected to filtering and analysis before being released into the atmosphere.

Thanks to the separation of the heat treatment into two stages, the apparatus can provide a complete combustion of the off-gas in a cost efficient manner and keep the dimensions of the apparatus small to allow for convenient handling and operation.

SHORT DESCRIPTION OF THE DRAWING

The invention will be further explained below with reference made to the

accompanying schematic drawings.

Fig. 1 is a longitudinal section showing the main components of an illustrating first embodiment of the incinerator apparatus; and

Fig. 2 is a longitudinal section showing the main components of a second embodiment of the incinerator apparatus.

Any reference made in the disclosure to spatial relations or directions, such as upper/lower, top/bottom or vertical/horizontal, are applied for the purpose of explaining the invention with reference to the drawing, and shall not necessarily be interpreted literally to limit the scope of the invention as claimed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An incinerator apparatus according to a first preferred embodiment of the present invention, adapted for thermochemical decomposition and destruction of organic and other combustible material, particularly combustible biological material and laboratory dry waste, comprises a container 1 having a wall 2 that rises from a container bottom 3 towards a top end of the container 1. The wall and bottom defines a cavity which can be filled with mixed organic waste (waste not illustrated). The cavity can be sealed by means of a lid 4 which is connectable to the otherwise open top end of the container. The container and lid may be arranged to engage in a locking condition, such as through a bayonet coupling or through any other suitable locking means. The lid carries a handle 5 by which the sealed container and its contents can be securely and comfortably handled by personnel.

The incinerator apparatus further comprises a heating vessel 6 having a wall 7 rising from a bottom 8 towards a top end of the heating vessel 6. The heating vessel can be sealed by means of a cover 9 connectable to the otherwise open top end of the heating vessel. The cover 9 can be firmly attached in the upper end of the heating vessel by means of inter- engaging elements or other suitable locking means. The heating vessel 6 has a diameter and length dimension that permits the sealed container 1 to be inserted in the heating vessel from the top end of the heating vessel while forming a gap and interspace 10 between the walls and bottoms, respectively, of the container and the heating vessel. The interspace 10 may amount to a radial distance of a few millimeters up to a few centimeters between the walls of the container and the heating vessel. To this purpose, vertically separating spacer elements 11 are arranged in the bottom of at least one of the container and the heating vessel. Horizontally separating insertion guides (not illustrated) may in a corresponding manner be arranged on at least one of the container and heating vessel walls. The container 1 and heating vessel 6 will both typically have the shape of circular cylinders, although cylinders of other sectional shapes are possible, as well as cylinders of non-continuous sectional shape having a wider upper end, e.g.

The container 1 and heating vessel 6 are both manufactured in high temperature resistant metal, such as high temperature steel or alloyed steel. For the container, a high temperature steel with excellent anti corrosive properties is preferably chosen. One or both members may advantageously be produced using an austenitic stainless steel or similar alloy steel, which is capable of being heated by

electromagnetic induction.

A coiled conductor 12 forms a heating spiral 13 that extends about the heating vessel 6. The heating spiral may be extended to reach from the bottom region of the heating vessel towards the upper end thereof for about one third of the height of the heating vessel. The coiled conductor 12 is effective for heating by induction the heating vessel and container to a temperature that causes carbonization of combustible material in the container. To this purpose the coiled conductor 12 is energized by alternating current at high frequency that is supplied to the coiled conductor from a power control circuit 14.

The power control circuit 14 may be designed to operate on a single phase, 1 10 or 230 V power grid.

In a preferred embodiment of the incinerator apparatus according to the present invention, the power control circuit 14 is designed to operate on 3-phase, 400 V, 50 Hz alternating current, which will be accessible through a power grid according to standard in many countries. In the power control circuit, a frequency converter converts the power grid frequency to an output frequency in the order of 5-50 kHz.

In a test using a 30 liter volume container it was confirmed that a power control circuit 14 sized to provide an out effect in the order of about 15-30 kW maximum being sufficient to generate induction heating of a 2 mm stainless steel wall to temperatures required to cause pyrolysis and carbonization of combustible material behind that wall. From this follows, that the heating vessel 6 can be seen as a primary heater from which heat is transferred to the container 1 by convection. Nevertheless, if produced in austenitic stainless steel or similar alloy steel, e.g., also the container wall may be subject to heating by induction as the conductor 12 is energized.

During the test the container interior temperature was measured to reach 700° C within 15 minutes during which the power control circuit energized the induction heating spiral with approximately 1 100 Amperes at a frequency of 35 kHz. The power consumption in this recited test was approximately 13 kW (20 Amps of 3- phase AC at 400 V) .

The inner temperature of the container is this way elevated to a level that causes pyrolysis and carbonization of the bio waste content, the process generating off-gas which eventually results in elevation of pressure inside the container. The pressure is relieved via an opening 15 that is formed generally in the upper region of the container 1. The opening 15 forms an off-gas passage which puts the interior of the container in flow connection with the interspace 10 between the container and the heating vessel. In the illustrated embodiment the off-gas entrance 15 into the interspace 10 is realized as a set of slots formed through the wall of the container. The slots may be distributed about parts of the circumference or about the entire circumference of the container.

The off-gas which has entered into the interspace 10 via the off-gas entrance 15 is permitted from the interspace to the atmosphere via an opening 16 that is formed generally in a lower region of the heating vessel. The opening 16 forms an off- gas passage which puts the interspace 10 in flow connection with atmosphere. In the illustrated embodiment, the off-gas exit 16 is realized as an opening through the bottom 8 of the heating vessel.

Thus in operation, the interspace 10 forms a heated first off-gas treatment chamber 10 defined between the heated walls 2 and 7 of the container and the heating vessel, respectively.

A valve 17 is arranged downstream from the off- gas exit 16. The valve 17 is controllable to permit, in open position, discharge of off-gas which has been subjected to the temperature in the first off-gas treatment chamber 10 before being released to atmosphere. From the foregoing reference to a tested unit it will be understood that it is feasible to raise the temperature in the first off-gas treatment chamber 10 to approximately 850° C.

In order to further ensure sufficient heating and neutralization of the off-gas before release to the atmosphere, the off-gas exit 16 opens into a pipe length that forms an off- gas pipe 18. A coiled conductor forms a heating spiral 19 about the off- gas pipe 18. The heating spiral 19 may be a part of the same coiled conductor 12 that forms the heating spiral 13 about the heating vessel and the container, or may be a separate conductor loop powered by the power control circuit 14. In the illustrated embodiment the off-gas pipe extends in axial direction of the heating vessel, continuing the first off- gas treatment chamber from the off- gas exit 16. The off- gas pipe may alternatively be otherwise directed from the off-gas exit 16, and may also be curved.

In order to enhance the transfer of heat from the wall of the off-gas pipe to the off- gas flowing through the off-gas pipe, flow affecting means may be arranged inside the off- gas pipe affecting the flow of off-gas through the off-gas pipe. The flow- affecting means can be realized as a flow restricting means arranged to reduce the cross-sectional area in the off-gas pipe. Such flow restricting means may comprise a perforated plate or a bundle of pipes covering the cross-section of the off-gas pipe, e.g.

The flow affecting means may alternatively be realized as a flow guiding means arranged to control the flow path of off- gas through the off-gas pipe. Such flow guiding means may include a helical insert or other type of flow guide or guiding vane arranged inside the off-gas pipe, e.g.

In the illustrated embodiment, a set of guide vanes 20 are arranged after each other as seen in the flow direction of off-gas through the off-gas pipe. Each guide vane 20 is shaped as a conical disc with its apex turned against the direction of flow. The diameter of the guide vanes 20 is slightly under-dimensioned with respect to the inner diameter of the off-gas pipe 18, resulting in a narrow annular gap 21 formed between the periphery of the guide vane and the wall of the off-gas pipe. The off-gas passing through the off-gas pipe upon release to atmosphere is thus allowed by internal pressure to pass close to the heated wall of the off-gas pipe, the off-gas this way being instantly heated to substantially the same temperature as the wall of the first off-gas treatment chamber 10.

The incinerator apparatus may be designed as a free standing apparatus adapted for use in any appropriate facility. For comfort of handling the apparatus as a whole may be housed in a heat insulating outer cabinet. Inside the cabinet, the heating vessel 6 may additionally be fitted into a shroud 22 of heat insulating material in order to further reduce heat radiation to the environment. The heat insulating shroud 22 may be extended in surrounding relation also to the off-gas pipe 18, as illustrated in the drawing.

In order to avoid overheating the heating spiral, the coiled conductor may be a tube through which a coolant is circulated for cooling purposes. Thus, in this

embodiment, the incinerator apparatus is connectable not only to an electric power supply N, but also to a cooling agent supply W comprising a pump 23 arranged for circulation of cooling agent in the tubular conductor coil. If appropriate, a cooling agent tank and / or a heat exchanger may be incorporated in the coolant circulation system.

However, the coiled conductor may alternatively be realized as a wire cable which avoids the need for a cooling agent. Regardless of whether being of tube or cable design, the coiled conductor may be produced from copper or other conductive material which is suitable for heating by induction the heating vessel, the container and the off-gas pipe. Operation controls may be installed in the cabinet, including inter alia the aforementioned power control circuit and frequency converter, as well as circuit breakers, fuses and other necessary electrical functions. If appropriate, control of power/ temperature and pressure can be made based on input from sensors and probes 24, 25, 26 arranged to monitor temperature and pressure in the container 1 and in the first off-gas treatment chamber 10. Particle filters 27 and gas analysis means 28 may be installed in the cabinet as well.

In order that the container interior and the first off-gas treatment chamber be properly vented before opening the container, e.g., an air injection system 29 is advantageously installed and operable for flushing free the interior spaces of the incinerator apparatus from off-gas residues remaining after completed incineration. The air injection system 29 may comprise a fan or compressor effective for injection of air into the apparatus, in order inter alia to counteract any negative pressure that might be formed in the first off-gas treatment chamber and the container upon cooling. The air injection system 29 may also comprise a plurality of nozzles.

Fig. 2 discloses a second preferred embodiment of the invention, where the treatment of the off-gas is separated into two stages. A first treatment is performed in the interspace 10 as described in detail above with regards to the first

embodiment, and a second treatment is performed in a second off-gas treatment chamber 34 located downstream from the first off- gas treatment chamber 10 and being in flow communication with said first off- gas treatment chamber 10.

In this embodiment, the heating of the container 1 is performed in a plurality of steps to allow the biological waste to dry and emit water and volatile gases to the interspace 10 before a target temperature in the interval 500-750° C is reached. The air supplied to the container 1 is limited to allow for a partial incineration only.

The off-gas from the container 1 undergoes a first heat treatment in the interspace 10, in the form of a pre-heating where a partial combustion takes place, and is then allowed to continue into a second off-gas treatment chamber 34 where a complete combustion at a higher temperature (at least 850° C) takes place before the off-gas is released into the atmosphere.

From the interspace 10, the off-gas is transported in a conduit 30, 31 which may be connected to the interspace 10 in the form of a first conduit 30, mounted in the same position as the off-gas pipe 18 described in connection with the first embodiment, or may alternatively be in the form of a second conduit 31 , connected to the interspace 10 as a horizontal extension of the bottom of the interspace 10. It is to be noted that the conduit 30, 31 could alternatively be connected at a different position than those disclosed by Fig. 2, but that it is advantageous to remove off- gas at the bottom of the interspace 10.

Thus, the off-gas is removed from the first off-gas treatment chamber 10 through the conduit 30, 31 and directed through the valve 17 towards the second off-gas treatment chamber 34, where it is mixed with a flow of pre-heated air from a second air injection system 32 and the mixture thus created of off-gas and air is ignited by ignition means 33 to allow a combustion in the second off-gas treatment chamber 34. The ignition means 33 comprises an ignition device that serves to perform the ignition, for instance by providing a flame or an electric arc. Alternatively, the off- gas and air mixture can be ignited by the high temperature in the second off-gas treatment chamber 34 itself.

In this embodiment, the second off-gas treatment chamber 34 comprises a length of pipe that is mounted in a series of curves to allow the off-gas to move along at a steady pace while at the same time remaining in the second off-gas treatment chamber 34 long enough to be completely combusted. The pipe can have a circular or rectangular cross-section, for instance. Also, alternative design of the chamber 34 are possible within the scope of the invention, provided that a full combustion of the off-gas is possible.

The air injection system 32 preferably comprises three nozzles placed radially inside the conduit between the valve 17 and the second off-gas heat treatment chamber

34, to allow for an efficient mixing of the air with the off-gas. Furthermore, the air is preferably pre-heated before being allowed to mix with the off-gas.

The off-gas and air mixture thus inserted into the second off-gas treatment chamber 34 is heated by induction generated by a second coil 35 to a temperature above 850°C and maintained there for at least two seconds, to allow for a complete combustion of the off-gas. The off-gas is then lead towards a second off-gas exit pipe 41, and along the way particle filters 38, gas analysis means 39 and a second valve 40 may be installed. Furthermore, the second off-gas treatment chamber 34 is preferably provided with opening means to allow for cleaning and repair. Said opening means are for instance in the form of a door or an opening with a sealable cover to provide access to an interior of the second off-gas treatment chamber 34 but still allow for a tight seal of the opening means during operation of the second off-gas treatment chamber 34 to prevent leakage.

The valve 17 and air injection system 32 are used to regulate the amount of off-gas and the proportions between off-gas and air that is supplied to the second heat treatment chamber 34, so that a complete combustion can take place. The second off-gas treatment chamber 34 is provided with a second coiled conductor 42 that forms a second heating spiral 35 and heated by induction in a manner similar to that described above with reference to the container 1 and heating vessel 6, and the second coiled conductor 42 is connected to a second power control circuit 37. A cooling agent supply N with a second pump 36 can also be provided to allow for cooling of the second heating spiral 35, and the second pump 36 can be provided with a second electrical power supply W2. In this embodiment, the pump 23 that provides power to the heating spiral 13 is denoted as a first pump 23 with a first electrical power supply. From the second off-gas treatment chamber 34, the off-gas can be allowed to pass a second particle filter 38 and second gas analysis means 39 before being released into the atmosphere via a second off-gas exit pipe 41. The release can be controlled by a third valve 40. A continuous analysis of the off-gas can thus be performed to ascertain that the combustion has been sufficient to allow for a release of the off- gas. Before release, the off-gas can be cooled by a heat exchanger (not shown), and the heat thus generated in the heat exchanger can be reinserted into the incinerator apparatus, for instance by heating the air inserted by the first air injection system 29. Also, a heat pump (not shown) can be used to further cool the off-gas and retain as much energy in the incinerator apparatus as possible Control and regulation of the components of the apparatus, such as the valve 17, air injection system 32, ignition means 33, second heating spiral 35, particle filter 38, gas analysis means 39 and second valve 40, among others, may be performed by the operation controls described in connection with the first embodiment above.

In this second embodiment, thanks to the highly efficient combustion of the off-gas in the second off-gas treatment chamber 34, the temperature in the container 1 can be kept lower than in the first embodiment, preferably in the interval 500-750°C, and be kept at low oxygen levels so that the combustible material inserted into the chamber 1 is subjected to a partial combustion only. Thereby, the apparatus can be made smaller and more cost efficient, while at the same time fulfilling the requirements for treatment of waste material.

Non-disclosed changes and modification to the above described embodiments are possible by applying the teachings provided herein without departing from the scope of the invention as defined in the accompanying claims.

Claims

1. An incinerator apparatus, effective for destroying organic and other combustible material, the apparatus comprising: a container ( 1) having a high-temperature resistant metal wall extending from a bottom of the container, the container defining a cavity for material to be destroyed, a heating vessel (6) having a high-temperature resistant metal wall extending from a bottom of the heating vessel, the heating vessel arranged to receive the container inserted therein, the container and the heating vessel dimensioned such that an interspace (10) is formed between the heating vessel and the container in inserted position, a coiled conductor ( 12; 13) arranged about the heating vessel, the coiled conductor effective upon energizing for heating by induction the heating vessel and container to a temperature that causes carbonization of combustible material in the container, characterized by an off- gas entrance ( 15) providing passage of off-gas from the interior of the container to the interspace, and an off-gas exit (16) providing passage of off-gas from the interspace towards the atmosphere, the interspace forming a heated first off-gas treatment chamber ( 10) defined between the heating vessel (6) and the container ( 1).

2. The incinerator apparatus of claim 1 , wherein the off- gas entrance ( 15) is arranged in an upper region of the first off-gas treatment chamber , and the off-gas exit ( 16) is arranged in a lower region of the first off- gas treatment chamber, the off- gas being forced in a descending flow through the first off-gas treatment chamber ( 10).

3. The incinerator apparatus of claim 1 or 2, wherein the off-gas exit (16) is in flow communication with atmosphere via a pipe length forming an off- gas pipe (18), the off-gas pipe surrounded by a coiled conductor (12; 19) effective for heating the off- gas pipe by induction.

4. The incinerator apparatus of claim 3, wherein a flow affecting means is arranged inside the off- gas pipe affecting the flow of off- gas through the off- gas pipe.

5. The incinerator apparatus of claim 4, wherein the flow affecting means is a flow restricting means arranged to reduce the cross-sectional area of the off-gas pipe, or a flow guiding means arranged to control the flow path of off-gas through the off-gas pipe.

6. The incinerator apparatus of claim 5, wherein the flow restricting means comprises a perforated plate or a bundle of pipes covering the cross-section of the off- gas pipe.

7. The incinerator apparatus of claim 5, wherein the flow guiding means comprises one or more guide vanes (20) arranged inside the off-gas pipe (18).

8. The incinerator apparatus of any of claims 3-7, wherein the off-gas pipe ( 18) extends from an off-gas exit ( 16) which is formed through the bottom (8) of the heating vessel.

9. The incinerator apparatus of any of claims 1 -8, wherein the heating vessel (6) is fitted into a shroud (22) of heat insulation material.

10. The incinerator apparatus of claim 9 as depending from any of claims 3-8, wherein the shroud (22) of heat insulation material is extended along the exterior of the off-gas pipe ( 18).

1 1. The incinerator apparatus of any previous claim, comprising a power control circuit ( 14) feeding the coiled conductor ( 12), the power control circuit operable on a 3 phase 400 V alternating current power grid.

12. The incinerator apparatus of any previous claim, wherein a power control circuit ( 14) comprises a frequency converter feeding alternating current at a frequency in the order of 5-50 kHz to the coiled conductor.

13. The incinerator apparatus of any previous claim, wherein the coiled conductor ( 12; 13; 19) is a tube connectable to a cooling agent circulation system (23).

14. The incinerator apparatus of any previous claim, wherein a valve ( 17) is arranged downstream from the off-gas exit and controllable to permit, in open position, discharge of off-gas to the atmosphere.

15. The incinerator apparatus of any previous claim, further comprising monitoring means (24; 25; 26) for monitoring at least one of the following operation

parameters: temperature, gas pressure, gas flow, gas constituents.

16. The incinerator apparatus of any previous claim, further comprising control means for controlling at least one of the following operation parameters:

temperature, gas pressure, gas flow.

17. The incinerator apparatus of any previous claim, comprising an air injection system (29) for regulation of internal gas pressure in the heating vessel and the container.

18. The incinerator apparatus of claim 1 or 2, further comprising a second off-gas treatment chamber (34) arranged in flow communication with the interspace (10) for receiving off-gas from the interspace (10), said second off-gas treatment chamber (34) being surrounded by a coiled conductor (35, 42) effective for heating the second off-gas treatment chamber (34) by induction.

19. A method for destroying organic and other combustible material, the method comprising: providing a container (1) having a high-temperature resistant metal wall extending from a bottom of the container, the container defining a cavity for material to be destroyed, providing a heating vessel (6) having a high-temperature resistant metal wall extending from a bottom of the heating vessel, and arranging the heating vessel to receive the container inserted therein by dimensioning the container and the heating vessel such that an interspace ( 10) is formed between the heating vessel and the container in inserted position, providing a coiled conductor ( 12; 13) about the heating vessel, and energizing the coiled conductor for heating the heating vessel and container by induction to a temperature that causes carbonization of combustible material in the container, characterized in that the off-gas produced from incineration is guided along the exterior of the container ( 1) for heat treatment before being released to the atmosphere.

20. The method of claim 19, wherein the off- gas is forced in a descending flow along the exterior of the container ( 1).

21. The method of claim 19 or 20, wherein the off-gas is subjected to a second heat treatment before being released to the atmosphere.