The waste material may be domestic, industrial or natural waste material, or combinations of such material.

Apparatus for the pyrolysis of waste material is well known. The waste material may be domestic and/or industrial waste material. The majority of the known types of apparatus operate such that they generate gas which is then fed to burners in order to heat a pyrolysis chamber forming part of the apparatus. This generation of gas and the subsequent feeding the gas to the burners is inefficient and environmentally unfriendly.

More specifically, the pyrolysis chamber is heated from the outside in the manner of heating a boiler, with most of the heat generated passing up through a chimney. The heat generated which passes up the chimney may be 70% of the overall heat generated. Thus large amounts of gas are wasted, with equally large amounts of heat being discharged to the atmosphere.

It is an aim of the present invention to obviate or reduce the above mentioned problems.

Accordingly, in one non-limiting embodiment of the present invention there is provided apparatus for the pyrolysis of waste material, which apparatus comprises a pyrolysis chamber which is heated by electrical heating means located within the pyrolysis chamber and in a floor part of the pyrolysis chamber.

The apparatus of the present invention is advantageous in that less power is required to heat the pyrolysis chamber than in the above mentioned known apparatus. This is because, in the apparatus of the present invention, all heat that is generated by the electrical heating means is able to be generated and used exactly where it is required in the pyrolysis chamber. An exhaust chimney is not needed and thus the apparatus is more environmentally friendly than the above mentioned known apparatus because the apparatus of the present invention does not need to discharge large amounts of heat into the atmosphere. The use of the electrical heating means enables the apparatus of the present invention to be left in a standby mode when it is not in use. This overcomes a well known problem of condensation which occurs in the known apparatus and often causes failure of chamber walls in the known apparatus.

Preferably, the apparatus of the present invention is one in which the pyrolysis chamber is an outer shell which is made of a metal and which has a heat insulating lining. The metal is preferably steel but other metals may be used if desired. Any suitable and appropriate heat insulating lining may be employed. Different parts of the pyrolysis chamber can have the same or different types of heat insulating material.

Preferably, the apparatus of the present invention is one in which the floor part of the pyrolysis chamber is formed by a floor of the outer shell and the heat insulating lining on the floor of the outer shell, and in which the electrical heating means is suspended within the heat insulating lining on the floor part of the pyrolysis chamber and such as not to contact the outer shell of the pyrolysis chamber, thereby to ensure that the outer shell of the pyrolysis chamber does not become electrically conducting. The heating means may advantageously be suspended on mounting blocks.

The heat insulating lining on the floor of the pyrolysis chamber may be formed of fire bricks. Other types of material may be used if desired.

Preferably, the electrical heating means comprises electrical heating elements wound on ceramic tubes. The ceramic tubes are able to provide support and insulation for the electrical heating elements. The ceramic tubes are also able to provide a means of supporting the electrical heating means, for example on the mounting blocks.

The electrical heating means may be a plurality of separate heaters.

Each separate heater may form a large high power source of heat, for example with an output of 10Kw.

The apparatus may be one in which an electrical supply for the electrical heating means is through fittings constructed to protect the electrical supply from contact with the outside of the pyrolysis chamber, and also constructed to maintain an airtight seal with the pyrolysis chamber.

The pyrolysis chamber is preferably constructed as a large long horizontally-extending chamber. Other shapes for the pyrolysis chamber may however be employed. Where the pyrolysis chamber is the large long horizontally-extending chamber, then it will usually have a door at each end.

The doors are advantageously constructed to be heavy.

The apparatus of the present invention may include a hearth which is positioned over the electrical heating means, which is composed of a plurality of ceramic plates, and over which the waste material passes during use of the apparatus.

The apparatus may include an external temperature controller and a thermal coupler, whereby the internal temperature of the pyrolysis chamber is able to be controlled over a wide temperature range.

The apparatus may include means for moving the waste material over the floor part of the pyrolysis chamber. The means for moving the waste material may be a rake system. The rake system may include a crank mounted internally with arms which move.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is a section through a pyrolysis chamber forming part of apparatus for the pyrolysis of waste material ; Figure 2 is another section of the pyrolysis chamber shown in Figure 1 ; Figure 3 shows in more detail the construction of the pyrolysis chamber shown in Figures 1 and 2; Figure 4 shows a ceramic hearth used in the pyrolysis chamber shown in Figures 1 and 2; Figure 5 is a plan view of a ceramic hearth for use in a pyrolysis chamber; Figure 6 is an end view of the hearth shown in Figure 5; Figure 7 is a plan view of a floor part of a pyrolysis chamber ; Figure 8 shows heaters mounted within a processing chamber; Figure 9 is a cross section of a heater assembly; Figure 10 is a side elevation showing a pyrolysis processing unit; and Figure 11 is a plan view of the pyrolysis processing unit shown in Figure 10.

Referring to Figures 1-4, there is shown a pyrolysis chamber 2 which forms part of apparatus for the pyrolysis of waste material. Domestic and/or industrial and/or natural waste material may be treated by the apparatus. The pyrolysis chamber 2 is heated by electrical heating means 4 located within the pyrolysis chamber 2 and in a floor part 6 of the pyrolysis chamber 2.

The pyrolysis chamber 2 comprises an outer shell 8 which is made from steel and which has a heat insulating lining 10. Positioned between the outer shell 8, the heat insulating lining 10, is a secondary heat insulating lining 12.

The floor part 6 of the pyrolysis chamber 2 is formed by a floor 14 of the outer shell 8, the heat insulating lining 10, and the secondary heat insulating lining 12 on the floor 14. The electrical heating means 4 is suspended within the heat insulating lining 10 on the floor part 6 of the pyrolysis chamber 2 as shown in Figure 1. The suspension of the electrical heating means 4 is such that the electrical heating means 4 does not contact the outer shell 8, thereby to ensure that the outer shell 8 does not become electrically conducting during use of the pyrolysis apparatus. The electrical heating means is suspended on mounting blocks. The heat insulating lining 10 is formed of firebricks. Other suitable and appropriate materials may be used if desired.

Electrical heating means comprises electrical heating elements wound on ceramic tubes. The ceramic tubes provide support and insulation for the electrical heating elements 4. The ceramic tubes also provide the means by which the electrical heating means is supported on the mounting blocks.

The electrical heating means is formed as a plurality of separate heaters. The separate heaters are large and give off high electrical power, for example of 1 lkw each.

An electrical supply (not shown) for the electrical heating means 4 is through fittings (not shown) constructed to protect the electrical supply from contact with the outer shell 8 of the pyrolysis chamber 2. The fittings are also constructed to maintain an airtight seal with the outer shell 8 of the pyrolysis chamber 2.

The pyrolysis chamber 2 is preferably constructed as a large long horizontally-extending chamber. This chamber has a heavy door at each end. The doors enable waste material to be introduced into the pyrolysis chamber 2, and removed from the pyrolysis chamber 2.

The pyrolysis chamber 2 includes a hearth 16 which is positioned over the electrical heating means 4. The hearth 16 is composed of a plurality of ceramic plates 18. A stream of the waste material passes over the hearth 16 during use of the apparatus of the invention.

The apparatus of the invention includes an external temperature controller (not shown) and a thermal coupler (not shown). The temperature controller and the thermal coupler enable the internal temperature of the pyrolysis chamber 2 to be able to be controlled over a wide temperature range.

The apparatus also includes means for moving the waste over the floor part 6 of the pyrolysis chamber 2. The means for moving the waste is preferably a rake system (not shown).

The outer shell 8 of the pyrolysis chamber 2 may be formed as a stainless steel welded casing. Figures 2 and 4 shows how the ceramic plates 18 can be supported on a steel support table 20.

Referring now to Figures 5 and 6, there is shown a hearth 22 comprising ceramic tubes 24 mounted on castellated supports 26. The castellated supports 26. stand on a floor 28. A gap 30, for example of at least 25mm, is provided between the ceramic tubes 24 and the floor 28.

Figure 7 shows how a floor may be provided with electric heaters 32 and fire bricks 34. The fire bricks 34 are laid out to form pockets for the electric heaters 32 to lay in.

Figure 8 shows apparatus in which heaters 36 are mounted within a processing chamber 38 for enabling maximum heat transfer. The processing chamber 38 is defined by a processor outer shell 40. Primary insulation 42 and secondary insulation 44 are provided as shown. The heaters 36 are positioned between ceramic plates 46 and the processor floor 48. Fire bricks 50 are spaced apart as shown to form spaces for the heaters 36. The ceramic plates 46 cover the heaters 36 as shown.

Figure 9 is a cross section through part of a heater assembly 52. The heater assembly 52 has heaters 54 set between ceramic plates 56 and fire bricks 58. The fire bricks 58 support the ceramic plates 56 as shown. Fire bricks 60 form a layer on a bed of the processor. Insulation 62 is provided as shown. The heaters 36 shown in Figure 8 and the heaters 54 as shown in Figure 9 may be of the same construction as the ceramic electric heaters shown in previous drawings.

Referring now to Figures 10 and 11, there is shown apparatus 64 for the pyrolysis of waste material. The apparatus 64 forms a pyrolysis processing unit. The apparatus 64 comprises delivery means 66 which may be in the form of an auger as shown or which may alternatively a conveyor, and which is for delivering an incoming waste stream. The waste stream is delivered to a dual stage feed hopper 68. A power take off point 70 is provided for the delivery means 66.

The apparatus 64 also comprises a main processor unit 72 and a gas scrubber tank 74 having an enclosed filtration system. The gas scrubber tank 74 has a dual stage distillation system 76 and a dry gas filter 78. Solid residue collects in a solid residue collection unit 80. An enclosed after- burner 82 is provided as shown. In Figure 11, it can be seen that the apparatus 64 also comprises a solid residue recovery unit 84 which is connected to the solid residue collection unit 80. The dual stage distillation system 76 has drain taps 86. The enclosed after-burner 82 has an exhaust 88. A draw pump 90 is provided in the conduit leading to the dual stage distillation system 76. The main processor unit 72 has a control panel 92 and access staging 94.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected. Thus, for example, the cross sectional shape of the pyrolysis chamber 2 shown in Figure 1 may be varied.